SEQUUS PHARMACEUTICALS INC
DEFM14A, 1999-02-17
PHARMACEUTICAL PREPARATIONS
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<PAGE>
 
                            SCHEDULE 14A INFORMATION
 
  Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of
                                      1934
 
Filed by the Registrant [X]
 
Filed by a Party other than the Registrant [_]
 
Check the appropriate box:
 
<TABLE>
<S>              <C>
[_] Preliminary  [_] Confidential, for Use of the Commission
    Proxy            Only (as Permitted by Rule 14a-6(e)(2))
    Statement
[X] Definitive
    Proxy
    Statement
[_] Definitive
    Additional
    Materials
[_] Soliciting Material Pursuant to (S)240.14a-11(c) or
    (S)240.14a-12
</TABLE>
 
                          SEQUUS PHARMACEUTICALS, INC.
      ------------------------------------------------------------
                (Name of Registrant as Specified In Its Charter)
 
      ------------------------------------------------------------
    (Name of Person(s) Filing Proxy Statement, if other than the Registrant)
 
Payment of Filing Fee (Check the appropriate box):
 
[X] No fee required.
 
[_] Fee computed on table below per Exchange Act Rules 14a-6(i)(4) and 0-11.
 
  (1) Title of each class of securities to which transaction applies:
    -------------------------------------------------------------------------
 
  (2) Aggregate number of securities to which transaction applies:
    -------------------------------------------------------------------------
 
  (3) Per unit price or other underlying value of transaction computed
      pursuant to Exchange Act Rule 0-11 (Set forth the amount on which the
      filing fee is calculated and state how it was determined):
    -------------------------------------------------------------------------
 
  (4) Proposed maximum aggregate value of transaction:
    -------------------------------------------------------------------------
 
  (5) Total fee paid:
    -------------------------------------------------------------------------
 
[_] Fee paid previously with preliminary materials.
 
[_] Check box if any part of the fee is offset as provided by Exchange Act Rule
    0-11(a)(2) and identify the filing for which the offsetting fee was paid
    previously. Identify the previous filing by registration statement number,
    or the Form or Schedule and the date of its filing.
 
  (1) Amount Previously Paid:
 
    -------------------------------------------------------------------------
 
  (2) Form, Schedule or Registration Statement No.:
 
    -------------------------------------------------------------------------
 
  (3) Filing Party:
 
    -------------------------------------------------------------------------
 
  (4) Date Filed:
 
    -------------------------------------------------------------------------
 
Notes:
<PAGE>

                    [LOGO OF SEQUUS PHARMACEUTICSLS, INC.]
 
                          SEQUUS Pharmaceuticals, Inc.
                               960 Hamilton Court
                              Menlo Park, CA 94025
 
                   Notice of Special Meeting of Stockholders
 
To the Stockholders of
SEQUUS Pharmaceuticals, Inc.:
 
NOTICE IS HEREBY GIVEN that SEQUUS Pharmaceuticals, Inc. will hold a special
meeting of its stockholders on March 16, 1999, at 10:00 a.m., local time, at
the SEQUUS corporate offices at 960 Hamilton Court, Menlo Park, California, for
the following purposes:
 
1. To consider and vote upon a proposal to approve and adopt the merger
   agreement, dated as of October 4, 1998, by and among SEQUUS, ALZA
   Corporation, a Delaware corporation, and Argyle Acquisition Corp., a
   Delaware corporation and a wholly owned subsidiary of ALZA ("Merger Sub"),
   providing for the merger of Merger Sub with and into SEQUUS. As a result of
   the merger, each outstanding share of the common stock, par value $.0001 per
   share, of SEQUUS would be converted into the right to receive 0.40 of a
   share of the common stock, par value $.01, of ALZA, and SEQUUS would become
   a wholly owned subsidiary of ALZA.
 
2. To transact such other business as may properly come before the special
meeting.
 
Only holders of record of SEQUUS common stock at the close of business on the
record date of January 19, 1999 will be entitled to notice of, and to vote at,
the special meeting. The affirmative vote of a majority of the outstanding
shares of SEQUUS common stock entitled to vote at the special meeting is
required to approve and adopt the merger agreement.
 
If your shares are held of record by a broker, bank or other nominee, you must
instruct your broker, bank or other nominee on how to vote your shares, or else
your shares will not be voted. If you attend the meeting, you may vote your
shares in person, which will revoke any previously executed proxy. FAILURE TO
RETURN A PROPERLY EXECUTED PROXY CARD OR TO VOTE AT THE SPECIAL MEETING WILL
GENERALLY HAVE THE SAME EFFECT AS A VOTE AGAINST THE MERGER.
 
                                          By Order of the Board of Directors
 
                                          Sally A. Davenport
                                          Corporate Secretary
 
Menlo Park, California
February 12, 1999
 
YOUR VOTE IS VERY IMPORTANT. WHETHER OR NOT YOU EXPECT TO ATTEND THE SPECIAL
MEETING, PLEASE SIGN, DATE AND PROMPTLY RETURN THE ENCLOSED PROXY CARD IN THE
ENCLOSED POSTAGE PREPAID ENVELOPE.
<PAGE>
 
                                PROXY STATEMENT
 
                     FOR SPECIAL MEETING OF STOCKHOLDERS OF
 
                          SEQUUS PHARMACEUTICALS, INC.
 
                               ----------------
 
                         PROSPECTUS OF ALZA CORPORATION
                           Up to 13,600,000 Shares of
                                  Common Stock
                                $0.01 par value
 
                               ----------------
 
The Board of Directors of SEQUUS Pharmaceuticals, Inc. and the Board of
Directors of ALZA Corporation have approved an agreement to merge SEQUUS with a
subsidiary of ALZA. As a result of this merger, SEQUUS would become a wholly
owned subsidiary of ALZA and ALZA would issue to SEQUUS stockholders 0.40 of a
share of ALZA common stock for each share of SEQUUS common stock that they own.
ALZA common stock trades on the New York Stock Exchange under the symbol "AZA."
 
The merger cannot be completed unless SEQUUS stockholders approve it. The
SEQUUS Board of Directors has scheduled a special meeting for SEQUUS
stockholders to vote on the merger as follows:
 
                                 March 16, 1999
 
                                   10:00 a.m.
 
                          SEQUUS Pharmaceuticals, Inc.
                               960 Hamilton Court
                             Menlo Park, California
 
This document gives you information about the proposed merger. ALZA has
provided the information about ALZA, and SEQUUS has provided the information
about SEQUUS. Please see "Where You Can Find More Information" on page 16 for
additional information about SEQUUS and ALZA on file with the Securities and
Exchange Commission.
 
This proxy statement/prospectus and the accompanying proxy card are first being
mailed to SEQUUS stockholders on or about February 12, 1999.
 
The merger involves certain risks to SEQUUS stockholders. See "Risk Factors"
beginning on page 18.
 
The Securities and Exchange Commission and state securities regulators have not
      approved or disapproved these securities or determined if this proxy
    statement/prospectus is truthful or complete. Any representation to the
                        contrary is a criminal offense.
 
                               ----------------
 
       The date of this proxy statement/prospectus is February 11, 1999.
<PAGE>
 
 
 
 
The following trademarks are used in this proxy statement/prospectus to
identify products and services of ALZA Corporation and its client companies:
Ditropan(R) XL(TM), D-TRANS(TM), DUROS(TM), E-TRANS(TM), OROS(R) and
Testoderm(R) TTS are trademarks of ALZA Corporation; Mycelex(R) Troche is a
trademark of Bayer AG; Elmiron(R) is a trademark of IVAX Corporation; Procardia
XL(R) is a trademark of Pfizer Inc.; Ethyol(R) is a trademark of US Bioscience,
Inc.
 
The following trademarks are used in this proxy statement/prospectus to
identify products of SEQUUS Pharmaceuticals, Inc.: Doxil(R); Caelyx(R);
Amphotec(R); Amphocil(R); and STEALTH(TM).
 
 
                                       2
<PAGE>
 
                               Table of Contents
 
<TABLE>
<CAPTION>
                                                                           Page
                                                                           ----
<S>                                                                        <C>
Summary...................................................................   5
  Summary Selected Historical Financial Information.......................   9
  ALZA Selected Historical Financial Data.................................   9
  SEQUUS Selected Historical Financial Data...............................  10
  Unaudited Selected Pro Forma Combined Financial Data....................  11
  Comparative Per Share Data..............................................  13
  Market Price Information................................................  14
Where You Can Find More Information.......................................  16
Incorporation of Certain Documents By Reference...........................  16
Special Note Regarding Forward-Looking Statements.........................  17
Risk Factors..............................................................  18
The Special Meeting.......................................................  25
  Matters to Be Considered at the Special Meeting; Recommendation of the
   SEQUUS Board...........................................................  25
  Record Date and Quorum..................................................  25
  Required Vote...........................................................  25
  Proxies.................................................................  26
  Solicitation of Proxies.................................................  26
  Independent Auditors....................................................  27
The Merger................................................................  28
  Background of the Merger ...............................................  28
  SEQUUS' Reasons for the Merger .........................................  30
  Opinion of SEQUUS' Financial Advisor ...................................  32
  ALZA's Reasons for the Merger...........................................  39
  Regulatory Requirements.................................................  40
  Interests of Certain Persons in the Merger..............................  40
  Accounting Treatment....................................................  42
  Material Federal Income Tax Consequences................................  42
  Absence of Appraisal Rights.............................................  44
The Merger Agreement and the Related Agreements...........................  45
  Effective Time; Effect of Merger........................................  45
  Conversion of Shares....................................................  45
  Treatment of Options and Warrants.......................................  46
  Stock Ownership Following the Merger....................................  46
  Representations and Warranties..........................................  47
  Conduct of ALZA's Business and SEQUUS' Business Prior to the Merger.....  47
  Conduct of Business Following the Merger................................  49
  No Solicitation.........................................................  49
  Fees, Expenses and Termination Fees.....................................  51
  Conditions to the Merger................................................  52
  Termination of the Merger Agreement.....................................  54
  Employee Benefits.......................................................  55
  Absence of Appraisal Rights.............................................  56
  Affiliate Agreements....................................................  56
  The Voting Agreements...................................................  57
Description of ALZA Capital Stock.........................................  58
  ALZA Common Stock.......................................................  58
  ALZA Preferred Stock....................................................  58
</TABLE>
 
                                       3
<PAGE>
 
<TABLE>
<S>                                                                         <C>
Comparison of Rights of Holders of ALZA Common Stock and Holders of SEQUUS
 Common Stock.............................................................   58
Unaudited Pro Forma Condensed Combined Financial Statements...............   61
Experts...................................................................   69
Legal Matters.............................................................   69
Stockholder Proposals.....................................................   69
Annex A   -- Agreement and Plan of Merger.................................  A-1
Annex B-1 -- Form of SEQUUS Affiliates Agreements.........................  B-1
Annex B-2 -- Form of ALZA Affiliates Agreements...........................  B-2
Annex C   -- Opinion of Credit Suisse First Boston........................  C-1
</TABLE>
 
                                       4
<PAGE>
 
                                    Summary
 
This summary highlights selected information from this document and does not
contain all of the information that is important to you. To understand the
merger fully and for a more complete description of the legal terms of the
merger, you should read carefully this entire document and the documents to
which we have referred you. See "Where You Can Find More Information" (page
16). We have included page references parenthetically to direct you to a more
complete description of the topics presented in this summary.
 
The Companies
 
ALZA Corporation
950 Page Mill Road
P.O. Box 10950
Palo Alto, California 94303-0802
Telephone: (650) 494-5222
 
ALZA is a research-based pharmaceutical company with leading drug delivery
technologies. ALZA applies its technologies to develop pharmaceutical products
with enhanced therapeutic value for its own portfolio and for many of the
world's leading pharmaceutical companies. ALZA's sales and marketing efforts
are currently focused in urology and oncology.
 
SEQUUS Pharmaceuticals, Inc.
960 Hamilton Court
Menlo Park, California 94025
Telephone: (650) 323-9011
 
SEQUUS is an integrated pharmaceutical company engaged in the development of
therapies for cancer and other diseases utilizing advanced drug delivery
technologies.
 
SEQUUS' Reasons for the Merger (page 30)
 
The SEQUUS Board of Directors has concluded that the merger will result in a
combined company with substantially more resources and greater development,
sales, distribution and manufacturing capabilities. The SEQUUS board believes
that the merger is fair to and in the best interests of SEQUUS and its
stockholders.
 
What SEQUUS Stockholders Will Receive in the Merger (page 44)
 
If the merger is approved, holders of SEQUUS common stock will receive 0.40 of
a share of ALZA common stock in exchange for each share of SEQUUS common stock
they own. ALZA will not issue fractional shares. SEQUUS stockholders will be
paid cash instead of fractional shares of ALZA common stock based on the market
value of ALZA common stock at the close of trading on the last trading day
before the merger occurs.
 
You should not send in your stock certificates until instructed to do so after
the merger is completed.
 
Federal Income Tax Consequences (page 41)
 
As a condition to the merger, which may be waived, each of SEQUUS and ALZA must
receive an opinion from its outside legal counsel that, as a general matter,
you will not be subject to any federal income tax as a result of the exchange
of SEQUUS common stock in the merger, except for taxes on any cash you receive
instead of fractional shares.
 
Tax matters are very complicated and the tax consequences of the merger to you
will depend on the facts of your own situation. We urge you to consult your tax
advisors for a full
 
                                       5
<PAGE>
 
understanding of the tax consequences of the merger to you.
 
The Special Meeting (page 25)
 
You will be asked to approve and adopt the merger agreement at a special
meeting of SEQUUS stockholders. The SEQUUS special meeting will be held at the
SEQUUS corporate offices at 960 Hamilton Court, Menlo Park, California on March
16, 1999 at 10:00 a.m.
 
Record Date; Voting Power (page 25)
 
You are entitled to vote at the special meeting if you owned shares of SEQUUS
common stock as of the close of business on December 30, 1998, the record date
for the special meeting.
 
On the record date, there were 32,627,715 shares of SEQUUS common stock allowed
to vote at the special meeting. SEQUUS stockholders will have one vote for each
share of SEQUUS common stock they owned on the record date.
 
Voting by Proxy (page 26)
 
You may vote on the merger by indicating on your proxy card how you want to
vote, and signing and mailing it in the enclosed return envelope. Please return
your proxy as soon as possible so that your shares may be represented at the
special meeting of the SEQUUS stockholders. If you sign and send in your proxy
card and do not indicate how you wish to vote, your proxy will be counted as a
vote in favor of the merger. If you do not vote, or you abstain, it will have
the effect of a vote against the merger.
 
Votes Required (page 25)
 
In order for the merger to proceed, a majority of the shares of SEQUUS common
stock outstanding on the record date must vote to approve and adopt the merger
agreement.
 
The Board's Recommendation to SEQUUS Stockholders (page 30)
 
The SEQUUS Board of Directors unanimously recommends that you vote "for" the
proposal to approve and adopt the merger agreement.
 
Fairness Opinion of Financial Advisor (page 32)
 
In deciding to approve the merger, the SEQUUS Board of Directors considered the
opinion of its financial advisor as to the fairness of the merger to you from a
financial point of view. This opinion is attached as Annex C to this proxy
statement/prospectus. We encourage you to read this opinion carefully.
 
SEQUUS' financial advisor performed several analyses in connection with
delivering its opinion. These analyses included comparing SEQUUS' and ALZA's
historical stock prices, comparing SEQUUS and ALZA to other publicly traded
companies, and estimating the relative values and contributions of SEQUUS and
ALZA based on past and estimated future performance.
 
Share Ownership of Management and Certain Stockholders
 
On the record date, directors of SEQUUS and their affiliates owned and were
allowed to vote 1,030,556 shares of SEQUUS common stock or approximately 3% of
the shares of SEQUUS common stock outstanding on the record date.
 
The directors of SEQUUS, in their capacity as stockholders, have agreed to vote
their SEQUUS common stock "for" approval and adoption of the merger agreement.
 
                                       6
<PAGE>
 
Interests of Certain Persons in the Merger (page 40)
 
You should note that a number of directors and executive officers of SEQUUS
have interests in the merger as employees and/or directors that are different
from, or in addition to, your interests as a stockholder. If we complete the
merger, Dr. I. Craig Henderson will become a member of the Board of Directors
of ALZA. Also, certain indemnification arrangements for existing directors and
officers of SEQUUS will be continued. In addition, SEQUUS has entered into
severance agreements with certain of its executive officers.
 
Ownership of ALZA Following the Merger (page 46)
 
We anticipate that SEQUUS stockholders will receive approximately 13,123,066
shares of ALZA common stock in the merger based on the number of shares of
SEQUUS common stock outstanding on February 10, 1999. Based on that number
existing SEQUUS stockholders will own approximately 9.7% of the ALZA common
stock outstanding after the merger.
 
Listing of ALZA Stock (page 52)
 
It is a condition to the merger that the ALZA common stock to be issued in
connection with the merger be approved for listing on the New York Stock
Exchange, subject to official notice of issuance. If we complete the merger,
stockholders will then be able to trade the shares of ALZA stock which they
receive in the merger on the New York Stock Exchange. In addition, SEQUUS stock
will no longer be listed on the Nasdaq National Market or any other exchange.
 
The Merger Agreement (page 45)
 
The merger agreement is attached as Annex A to this document. We encourage you
to read the merger agreement. It is the legal document governing the merger.
 
Conditions to the Merger (page 52)
 
We will complete the merger only if we satisfy (or waive) several conditions,
including the following:
 
 . holders of a majority of the outstanding common stock of SEQUUS approve and
  adopt the merger agreement;
 
 . all material authorizations, consents, orders or approvals of, or filings
  with, any government entity shall have been obtained or filed;
 
 . no court or government body or authority has acted to restrain or prohibit
  the consummation of the merger;
 
 . each party's representations and warranties contained in the merger agreement
  continue to be accurate in all material respects;
 
 . SEQUUS and ALZA shall have complied with their respective covenants contained
  in the merger agreement in all material respects;
 
 . no material adverse effect has occurred with respect to ALZA or SEQUUS;
 
 . SEQUUS' counsel and ALZA's counsel deliver opinions regarding certain federal
  income tax consequences of the merger; and
 
 . SEQUUS' independent auditors and ALZA's independent auditors deliver letters
  stating their concurrence with SEQUUS
 
                                       7
<PAGE>
 
  management's and ALZA management's conclusion as to the appropriateness of
  pooling-of-interests accounting treatment for the merger.
 
Termination of the Merger Agreement (page 54)
 
The Board of Directors of both companies can jointly agree to terminate the
merger agreement at any time without completing the merger. One or both
companies can terminate the merger agreement under various circumstances,
including if:
 
 . the merger is not completed by April 1, 1999;
 
 . the Board of Directors of SEQUUS accepts a "Superior Proposal" as further
  described in "The Merger Agreement and Related Agreements";
 
 . the required vote of the SEQUUS stockholders is not received; or
 
 . a court or other government entity prohibits the merger.
 
Termination Fees (page 51)
 
In connection with the termination of the merger agreement under certain
circumstances, SEQUUS would be required to pay to ALZA a termination fee of $25
million.
 
Regulatory Requirements (page 40)
 
We are prohibited by U.S. antitrust laws from completing the merger until after
we have furnished certain information and materials to the Antitrust Division
of the Department of Justice and the Federal Trade Commission and a required
waiting period has ended. ALZA and SEQUUS have each filed the required
notification and report forms with the Antitrust Division and the Federal Trade
Commission, and the waiting period for those filings has expired. However, the
Antitrust Divison and the Federal Trade Commission continue to have the
authority to challenge the merger on antitrust grounds before or after the
merger is completed.
 
No Appraisal Rights (page 44)
 
SEQUUS and ALZA are both organized under Delaware law. Under Delaware law,
stockholders of SEQUUS have no rights to an appraisal of the value of their
shares in connection with the merger.
 
Accounting Treatment (page 42)
 
We expect the merger will be accounted for as a pooling of interests, which
means that we will treat our companies as if they had always been combined for
accounting and financial reporting purposes.
 
                                       8
<PAGE>
 
 
               Summary Selected Historical Financial Information
 
We are providing the following information to aid you in your analysis of the
financial aspects of the merger. We derived this information from audited
financial statements for 1993 through 1997 and unaudited financial statements
for the nine months ended September 30, 1997 and 1998. This information is only
a summary and you should read it in conjunction with each company's historical
financial statements (and related notes) and Management's Discussion and
Analysis of Financial Condition and Results of Operations contained in the
annual reports, quarterly reports and other information on file with the
Securities and Exchange Commission. See "Where You Can Find More Information"
on page 16.
 
Net income (loss) and earnings (loss) per share--diluted for the nine months
ended September 30, 1997, reflects a total of $353.5 million (or $4.13 per
share, diluted) of charges, including a $247.0 million charge and $8.0 million
of interest expense related to ALZA's distribution of shares of Crescendo
Pharmaceuticals Corporation, $87.0 million for acquired in-process research and
development and an asset write-down of $11.5 million. Net income (loss) and
earnings (loss) per share--diluted for the year ended December 31, 1997,
reflects a total of $368.7 million (or $4.30 per share, diluted) of charges
(net of a tax benefit of $8.1 million), including a $247.0 million charge and
$8.0 million of interest expense related to ALZA's distribution of shares of
Crescendo Pharmaceuticals Corporation, $108.5 million for acquired in-process
research and development, an asset write-down of $11.5 million and costs of
$1.8 million related to workforce reductions.
 
                    ALZA Selected Historical Financial Data
                    (in millions, except per share amounts)
 
<TABLE>
<CAPTION>
                           Nine Months
                              Ended
                          September 30,         Year Ended December 31,
                          --------------  ------------------------------------
                           1998   1997     1997     1996   1995   1994   1993
                          ------ -------  -------  ------ ------ ------ ------
<S>                       <C>    <C>      <C>      <C>    <C>    <C>    <C>
Historical Consolidated
 Statement of Operations
 Data:
Total revenues........... $427.8 $ 338.2  $ 464.4  $413.1 $324.6 $261.2 $214.6
Net income (loss)........   86.9  (273.8)  (261.1)   92.4   72.4   58.1   45.6
Earnings (loss) per
 share--diluted.......... $ 0.97 $ (3.22) $ (3.07) $ 1.08 $ 0.88 $ 0.71 $ 0.57
Weighted average shares
 and assumed
 conversions--diluted....  113.3    85.0     85.1    97.2   82.6   82.3   79.9
</TABLE>
 
<TABLE>
<CAPTION>
                                                    December 31,
                         September 30, --------------------------------------
                             1998        1997     1996    1995   1994   1993
                         ------------- -------- -------- ------ ------ ------
<S>                      <C>           <C>      <C>      <C>    <C>    <C>
Historical Consolidated
 Balance Sheet Data:
Working capital.........   $  295.6    $  253.4 $  494.8 $273.2 $209.0 $(87.8)
Total assets............    1,479.7     1,369.2  1,613.7  937.2  806.3  621.8
Convertible
 debentures(/1/)........      917.3       902.6    882.3  362.9  344.6    --
Total long-term debt....      945.3       927.6    893.2  363.0  345.5    1.8
Total stockholders'
 equity.................      415.9       301.2    596.7  454.6  364.5  306.7
</TABLE>
- --------
(1) Included in total long-term debt.
 
                                       9
<PAGE>
 
                   SEQUUS Selected Historical Financial Data
                    (in millions, except per share amounts)
 
<TABLE>
<CAPTION>
                            Nine Months
                               Ended
                           September 30,            Year Ended December 31,
                          ----------------  -------------------------------------------
                           1998     1997     1997     1996     1995     1994     1993
                          -------  -------  -------  -------  -------  -------  -------
<S>                       <C>      <C>      <C>      <C>      <C>      <C>      <C>
Historical Statement of
 Operations Data:
Total revenues..........  $  46.8  $  27.3  $  40.0  $  33.0  $   2.0  $   3.8  $   6.8
Net loss................     (5.5)   (20.0)   (23.5)   (17.2)   (33.6)   (29.2)   (19.7)
Loss per share--
 diluted................  $ (0.18) $ (0.66) $ (0.78) $ (0.59) $ (1.54) $ (1.54) $ (1.05)
Weighted average
 shares--diluted........     31.3     30.3     30.4     28.9     21.8     19.0     18.8
<CAPTION>
                                                         December 31,
                           September 30,    -------------------------------------------
                               1998          1997     1996     1995     1994     1993
                           -------------    -------  -------  -------  -------  -------
<S>                       <C>      <C>      <C>      <C>      <C>      <C>      <C>
Historical Balance Sheet
 Data:
Working capital.........      $ 23.5        $  23.6  $  38.6  $  45.8  $   6.3  $  31.9
Total assets............        47.9           42.2     55.0     57.8     18.2     45.2
Long-term debt..........         3.5            4.6      --       --       --       --
Total stockholders'
 equity.................        28.5           25.8     44.3     49.6     10.9     39.3
</TABLE>
 
                                       10
<PAGE>
 
              Unaudited Selected Pro Forma Combined Financial Data
 
We expect that the merger will be accounted for as a pooling of interests,
which means that for accounting and financial reporting purposes, we will treat
our companies as if they had always been combined.
 
We have presented below unaudited pro forma combined financial information that
reflects the pooling-of-interests method of accounting. We have included this
information to give you a better picture of what the results of operations and
financial position of the combined businesses of ALZA and SEQUUS might have
been had the merger occurred on an earlier date. The unaudited pro forma
combined statement of operations data combines information from the historical
consolidated statements of operations of ALZA and the historical statements of
operations of SEQUUS and presents that information as if we had completed the
merger on January 1, 1995. The unaudited pro forma combined balance sheet data
combines information from the historical consolidated balance sheet of ALZA and
the historical balance sheet of SEQUUS and presents that information as if we
had completed the merger on September 30, 1998.
 
We are providing this information for illustrative purposes only. It does not
necessarily reflect what the results of operations or financial position of the
combined company would have been if the merger had actually occurred at the
beginning of the earliest period presented. This information also does not
necessarily indicate what the combined company's future operating results or
consolidated financial position will be. This information does not reflect the
effect of any potential changes in revenues or any operating efficiencies which
may result from combining the resources of our companies.
 
As a result of the merger, ALZA anticipates that a pretax charge of
approximately $15 million for direct merger-related transaction costs will be
recognized in the quarter in which the merger is completed. These costs consist
primarily of professional and registration fees and have been reflected as an
adjustment to the Pro Forma Combined Condensed Balance Sheet at September 30,
1998.
 
In addition, the merged companies are expected to incur certain costs in
connection with integrating the operations of ALZA and SEQUUS. ALZA expects to
recognize a pretax charge currently estimated to be in the range of $5 million
to $15 million in the quarter in which the merger is completed. The charge is
expected to include employee severance costs and costs related to consolidation
of duplicate facilities. This charge is not reflected in the pro forma
financial information.
 
Net income (loss) and earnings (loss) per share--diluted for the nine months
ended September 30, 1997 reflect a total of $353.5 million (or pro forma $3.63
per share, diluted) of charges, including a $247.0 million charge and $8.0
million of interest expense related to ALZA's distribution of shares of
Crescendo Pharmaceuticals Corporation, $87.0 million for acquired in-process
research and development and an asset write-down of $11.5 million. Pro forma
combined net income excluding these items would have been $67.8 million (or pro
forma $0.69 per share, diluted). Net income (loss) and earnings (loss) per
share--diluted for the year ended December 31, 1997 reflect a total of
 
                                       11
<PAGE>
 
$368.7 million (or pro forma $3.77 per share, diluted) of charges, net of a tax
benefit of $8.1 million, including a $247.0 million charge and $8.0 million of
interest expense related to ALZA's distribution of shares of Crescendo
Pharmaceuticals Corporation, $108.5 million for acquired in-process research
and development, an asset write-down of $11.5 million and costs of $1.8 million
related to workforce reductions. Pro forma combined net income excluding these
items would have been $93.4 million (or pro forma $0.94 per share, diluted).
 
Please see "Unaudited Pro Forma Condensed Combined Financial Statements" on
pages 60 through 67 for a more detailed explanation of this analysis.
 
<TABLE>
<CAPTION>
                                          Nine Months
                                             Ended       Year Ended December
                                         September 30,           31,
                                         --------------  ---------------------
                                          1998   1997     1997    1996   1995
                                         ------ -------  ------  ------ ------
                                           (in millions, except per share
                                                      amounts)
<S>                                      <C>    <C>      <C>     <C>    <C>
Pro Forma Combined Statement of
 Operations Data:
Total revenues.......................... $474.6 $ 365.5  $504.4  $446.1 $326.6
Net income (loss).......................   83.6  (285.8) (275.2)   82.1   52.2
Earnings (loss) per share--diluted...... $ 0.83 $ (2.94) $(2.83) $ 0.84 $ 0.56
Weighted average shares and assumed
 conversions--diluted...................  101.0    97.1    97.3    97.4   93.3
</TABLE>
 
<TABLE>
<CAPTION>
                                                              September 30, 1998
                                                              ------------------
                                                                (in millions,
                                                               except per share
                                                                   amounts)
<S>                                                           <C>
Pro Forma Combined Balance Sheet Data:
Cash, cash equivalents and short-term investments............      $  185.2
Working capital..............................................         304.1
Total assets.................................................       1,567.6
Convertible debentures(/1/)..................................         917.3
Total long-term debt.........................................         948.8
Total stockholders' equity...................................         469.4
Book value per share.........................................          4.71
</TABLE>
- --------
(1) Included in total long-term debt.
 
                                       12
<PAGE>
 
                           Comparative Per Share Data
                                  (unaudited)
 
The following table sets forth information on the earnings and book value per
common share for our respective companies on a historical and pro forma
combined basis and indicates the relative earnings and book values of the
companies for the periods covered.
 
Note that historical and pro forma book value per share is calculated by
dividing stockholders' equity at the end of the period by the number of common
shares outstanding at the end of the period. Pro forma combined earnings (loss)
per SEQUUS share-diluted and pro forma combined book value per SEQUUS share
were calculated by multiplying the respective unaudited pro forma combined
earnings per ALZA share amounts by the exchange ratio of .40 of a share of ALZA
common stock per share of SEQUUS common stock.
 
<TABLE>
<CAPTION>
                                      Nine Months
                                         Ended
                                     September 30,   Year Ended December 31,
                                     --------------  -------------------------
                                      1998    1997    1997     1996     1995
                                     ------  ------  -------  -------  -------
<S>                                  <C>     <C>     <C>      <C>      <C>
ALZA historical
Earnings (loss) per share--dilut-
 ed................................  $ 0.97  $(3.22) $ (3.07) $  1.08  $  0.88
Book value per share...............    4.78
Pro forma combined per ALZA share
Earnings (loss) per share--dilut-
 ed................................    0.83   (2.94)   (2.83)    0.84     0.56
Book value per share...............    4.71
SEQUUS historical
Loss per share--diluted............  $(0.18) $(0.66) $ (0.78) $ (0.59) $ (1.54)
Book value per share...............    0.90
Pro forma combined per SEQUUS share
Earnings (loss) per share--dilut-
 ed................................    0.33   (1.18)   (1.13)    0.34     0.22
Book value per share...............    1.88
</TABLE>
 
The information set forth above is only a summary and you should read it in
conjunction with the Unaudited Pro Forma Condensed Combined Financial
Statements on pages 58 through 65 and the respective audited and unaudited
financial statements of ALZA and SEQUUS. We incorporate the audited and
unaudited consolidated financial statements of ALZA and the audited and
unaudited financial statements of SEQUUS into this proxy statement/prospectus
by reference. See "Where You Can Find More Information" on page 16.
 
                                       13
<PAGE>
 
                            Market Price Information
 
Set forth below are the last reported sale prices of ALZA common stock and
SEQUUS common stock on October 2, 1998, the last trading day prior to the
public announcement of the merger agreement, and on February 10, 1999, the last
trading day prior to the date of this proxy statement/prospectus, as well as
the equivalent pro forma sale prices of SEQUUS common stock on those dates, as
determined by multiplying the applicable last reported sale price of ALZA
common stock on the NYSE by the exchange ratio. The SEQUUS Equivalent column
reflects the potential value of the ALZA common stock to be received by SEQUUS
stockholders per SEQUUS share as a result of the exchange ratio. A comparison
of the SEQUUS Equivalent column and the SEQUUS Common Stock column reflects the
potential difference in the value of the ALZA common stock to be received over
the price of the SEQUUS common stock as of the same dates.
 
<TABLE>
<CAPTION>
                                         ALZA        SEQUUS
                                     Common Stock Common Stock SEQUUS Equivalent
                                     ------------ ------------ -----------------
<S>                                  <C>          <C>          <C>
October 2, 1998.....................   $42.4375     $10.8750       $16.9750
February 10, 1999...................   $51.6875       $19.25        $20.675
</TABLE>
 
ALZA common stock is traded on the NYSE under the symbol "AZA". The table below
sets forth the high and low closing sale prices per share of ALZA common stock
for the periods indicated, which indicates how ALZA's stock price has
fluctuated over the quarterly and annual periods covered. For current price
information with respect to the ALZA common stock, SEQUUS stockholders are
urged to consult publicly available sources. No assurance can be given as to
future prices of, or markets for, ALZA common stock.
 
<TABLE>
<CAPTION>
                                                             ALZA Common Stock
                                                             ------------------
                                                               High      Low
                                                             --------- --------
<S>                                                          <C>       <C>
Fiscal Year Ended December 31, 1996
First Quarter............................................... $34 7/8   $24 3/8
Second Quarter..............................................  32 1/2    26 3/8
Third Quarter...............................................  27 3/4    24
Fourth Quarter..............................................  29        25 1/8
Fiscal Year Ended December 31, 1997
First Quarter...............................................  31 3/8    24 7/8
Second Quarter..............................................  31 3/8    25 1/2
Third Quarter...............................................  32 1/2    28 1/16
Fourth Quarter..............................................  31 13/16  24 7/8
Fiscal Year Ending December 31, 1998
First Quarter...............................................  44 13/16  31 11/16
Second Quarter..............................................  52 1/16   41 7/16
Third Quarter...............................................  44 3/4    34 3/8
Fourth Quarter .............................................  54        45 1/4
Fiscal Year Ended December 31, 1999
First Quarter through February 10th.........................  53 5/8    43 1/4
</TABLE>
 
                                       14
<PAGE>
 
 
SEQUUS common stock is quoted on Nasdaq and traded under the symbol "SEQU". The
table below sets forth for the periods indicated the high and low closing sale
prices per share of SEQUUS common stock. For current price information with
respect to the SEQUUS common stock, SEQUUS stockholders are urged to consult
publicly available sources. SEQUUS has never declared or paid any cash
dividends on SEQUUS common stock.
 
<TABLE>
<CAPTION>
                                                             SEQUUS Common Stock
                                                             --------------------
                                                                High      Low
                                                             ---------- ---------
<S>                                                          <C>        <C>
Fiscal Year Ended December 31, 1996
First Quarter............................................... $19 1/2    $12 3/8
Second Quarter..............................................  22 1/2     13 3/4
Third Quarter...............................................  20 1/8     11 1/2
Fourth Quarter..............................................  17         12 1/2
Fiscal Year Ended December 31, 1997
First Quarter...............................................  16 3/8      7 1/8
Second Quarter..............................................   8 5/16     5 3/8
Third Quarter...............................................   8 31/32    5 1/2
Fourth Quarter..............................................   9 5/8      6 5/8
Fiscal Year Ending December 31, 1998
First Quarter...............................................  11 3/8      6 2/5
Second Quarter..............................................  13          9 2/3
Third Quarter...............................................  11 3/8      6
Fourth Quarter .............................................  20 1/2      9
Fiscal Year Ended December 31, 1999
First Quarter through February 10th.........................  20 1/4     16 1/2
</TABLE>
 
 
                                       15
<PAGE>
 
                      Where You Can Find More Information
 
ALZA and SEQUUS each file annual, quarterly and special reports, proxy
statements and other information with the United States Securities and Exchange
Commission. You may read and copy any document filed by ALZA or SEQUUS at the
SEC's public reference facilities. Please call the SEC at 1-800-SEC-0330 for
further information about its public reference facilities. These SEC filings
are also available to the public at the SEC's web site at "http://www.sec.gov".
Reports, proxy statements and other information concerning ALZA can also be
inspected at the offices of the New York Stock Exchange, 20 Broad Street, New
York, New York 10005. Reports, proxy statements and other information
concerning SEQUUS can be inspected at the Nasdaq National Market, Operations,
1735 K Street, N.W., Washington, D.C. 20006.
 
This proxy statement/prospectus incorporates certain documents by reference.
You can obtain copies of the documents relating to ALZA, without charge, by
contacting ALZA Corporate and Investor Relations department at:
 
                                ALZA Corporation
                               950 Page Mill Road
                                 P.O. Box 10950
                        Palo Alto, California 94303-0802
                                 (650) 494-5222
 
You can obtain copies of the documents relating to SEQUUS, without charge, by
contacting its Corporate Secretary at:
 
                          SEQUUS Pharmaceuticals, Inc.
                               960 Hamilton Court
                          Menlo Park, California 94025
                                 (650) 323-9011
 
In order to ensure timely delivery of the documents, any requests should be
made by March 1, 1999.
 
                Incorporation of Certain Documents By Reference
 
The SEC allows us (ALZA and SEQUUS) to "incorporate by reference" the
information we file with the SEC which means that we can disclose important
information to you by referring you to documents that we have previously filed
with the SEC. The information incorporated by reference is considered to be a
part of this proxy statement/prospectus. Any later information that we file
with the SEC will automatically update and supersede this information.
 
We incorporate by reference the documents listed below, and any further filings
made with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Securities
Exchange Act of 1934 until the offering of the securities is terminated. This
proxy statement/prospectus is part of a registration statement on Form S-4
filed by ALZA with the SEC (Registration No.     ).
 
                                       16
<PAGE>
 
The ALZA documents we incorporate by reference are its:
 
  . Annual Report on Form 10-K and         . Quarterly Report on Form 10-Q
    Form 10-K/A for the fiscal year          for the quarter ended September
    ended December 31, 1997                  30, 1998
 
 
  . Quarterly Report on Form 10-Q          . Current Report on Form 8-K filed
    for the quarter ended March 31,          with the SEC on October 15, 1998
    1998
 
 
                                           . The description of ALZA common
  . Quarterly Report on Form 10-Q            stock in ALZA's Registration
    for the quarter ended June 30,           Statements on Form 8-A filed May
    1998                                     14, 1992 under the Securities
                                             Exchange Act of 1934 and any
                                             amendment or report filed for
                                             the purpose of updating that
                                             description.
 
The SEQUUS documents we incorporate by reference are its:
 
  . Annual Report on Form 10-K and         . Current Report on Form 8-K
    Form 10-K/A for the fiscal year          filed with the SEC on October
    ended December 31, 1997                  15, 1998
 
 
  . Quarterly Report on Form 10-Q          . Current Reports on Form 8-K
    for the quarter ended March 31,          filed with the SEC on December
    1998                                     17, 1998
 
 
  . Quarterly Report on Form 10-Q          . Current Reports on Form 8-K/A
    for the quarter ended June 30,           filed with the SEC on February
    1998                                     10, 1999
 
  . Quarterly Report on Form 10-Q
    for the quarter ended September
    30, 1998
 
 
               Special Note Regarding Forward-Looking Statements
 
This proxy statement/prospectus contains and incorporates by reference certain
statements that constitute "forward-looking statements" within the meaning of
the Private Securities Litigation Reform Act of 1995. These forward-looking
statements include all statements which are not statements of historical fact
such as statements as to beliefs, expectations, anticipations, intentions or
similar words. Those statements are subject to risks, uncertainties and
assumptions, including, those described in "Risk Factors" (see page 19). If any
of those risks or uncertainties affect the business of either of the companies
or should underlying assumptions prove incorrect, ALZA's or SEQUUS' actual
results, performance or achievements in 1998 and beyond could differ materially
from those expressed in, or implied by, those forward-looking statements.
 
                                       17
<PAGE>
 
                                  Risk Factors
 
You should carefully consider the following factors in evaluating whether to
vote to approve the merger agreement.
 
I. Risks Related to the Merger
 
The following risks relate to the merger and to the combination of the
businesses of ALZA and SEQUUS.
 
The exchange ratio is fixed so the consideration received by SEQUUS
stockholders would decline if the price of ALZA stock goes down.
 
The exchange ratio is fixed at 0.40 of a share of ALZA common stock for each
SEQUUS share and will not be adjusted in the event of changes in the prices of
either the ALZA common stock or the SEQUUS common stock. If the market price of
the ALZA common stock decreases, the value of the consideration to be received
by the SEQUUS stockholders would also decrease. Neither company may terminate
the merger agreement or elect not to complete the merger solely because of
changes in their stock prices.
 
The price of ALZA common stock on the date of the merger may be different from
its price on the date of the merger agreement, the date of this proxy
statement/prospectus or the date of the special meeting. See "--Volatility of
Stock Prices" below. Because the merger may occur on a date later than the
special meeting, the price of ALZA common stock on the date of the special
meeting may not be indicative of its price on the date of the merger. You are
urged to obtain current market quotations for ALZA common stock. See "The
Merger Agreement and the Related Agreements--Conversion of Shares" and "--
Conditions to the Merger."
 
Integration of the two businesses may be difficult to achieve, which may
adversely affect operations.
 
ALZA and SEQUUS have different technologies, products and business operations
that have operated independently. The combination of these two businesses after
the merger may be difficult. If we fail to integrate the businesses
successfully the operating results of the combined company could be adversely
affected and the combined company may not achieve the benefits or operating
efficiencies that we hope to obtain from the merger. The uncertainties of
whether SEQUUS and ALZA employees will remain with SEQUUS, ALZA and/or the
combined company after announcement of the merger and during the integration
process may affect business operations of each company. It may not be possible
to retain enough key employees of SEQUUS for SEQUUS or the combined company to
operate its business effectively during the period prior to or after the
merger. We do not know whether the products, systems and personnel of the two
companies will be fully compatible. The lengthy development period for
pharmaceutical products requires that we make decisions far in advance, and it
may be difficult for the combined company to change certain existing
development programs or to adjust resources to achieve the desired results of
the combination.
 
The costs of completing the merger are substantial, and may affect our results
of operations.
 
Completion of the merger will result in total pre-tax costs estimated at
between $20 and $30 million, primarily relating to costs associated with
combining the businesses of the two
 
                                       18
<PAGE>
 
companies and the fees of financial advisors, attorneys, consultants and
accountants. Although we do not believe that the merger costs will exceed our
estimate, our estimate may not be correct and unanticipated events could occur
that will substantially increase the costs of combining the two companies. In
any event, costs associated with the merger are likely to negatively affect
ALZA's results of operations in the quarter in which the merger is completed.
 
The price of ALZA stock fluctuates and may decline in the future.
 
The market price of ALZA's common stock is volatile and may decline. A decline
in the market price of ALZA common stock would reduce the value of the
consideration to be received by the SEQUUS stockholders in the merger. The
market price of ALZA's common stock fluctuates significantly in response to
variations in quarterly operating results, announcements of new commercial
products by ALZA or its competitors, regulatory developments in both the United
States and foreign countries, developments or disputes concerning patent or
proprietary rights, health care reform and regulation, and economic and other
external factors. See "Summary--Market Price Information."
 
II. Risks Related to Operations
 
The following risks relate to the ongoing business and operations of ALZA,
SEQUUS and, if the merger is completed, the resulting combined company.
 
ALZA's expanded sales organization may not be successful.
 
ALZA significantly expanded its sales organization during 1998, and the
profitability of its operations will depend on its ability to use this expanded
sales force effectively. ALZA's expanded sales organization may not succeed in
increasing ALZA's revenues or profits.
 
Many of ALZA's and SEQUUS' products are new and may not be successful.
 
Many of the products sold by ALZA and SEQUUS have been introduced only during
the last few years. Several are relatively new products that had no established
market when they were introduced. Others are used for the treatment of
conditions that doctors may under-diagnose or not completely understand. It may
be difficult for the combined company to achieve adequate market acceptance and
sales levels for these new products.
 
The merger may restrict or delay successful promotion and sale of ALZA and
SEQUUS products.
 
Following the merger, the combined company will commercialize its products
through a combined marketing and sales organization. Training and organizing
the combined organization, including training the sales force on issues
relating to new products, will be costly and may result in delays in achieving
the sales levels that we hope to achieve through the merger. In addition, ALZA
and SEQUUS each face similar marketing risks, including those set forth below,
and combining the marketing and sales organizations may increase these risks:
 
 .  Most or all of the products which SEQUUS and ALZA sell face direct
   competition from other products used for the same purpose.
 
 . Government regulations limit the approved uses for ALZA and SEQUUS products,
  and restrict ALZA and SEQUUS from promoting their products for unapproved
  uses even though, with respect to certain products, scientific information
  has been published supporting other uses that are not yet approved.
 
 . Some ALZA and SEQUUS products may not be paid for fully by government
  agencies
 
                                       19
<PAGE>
 
  or managed care organizations, in particular for uses (such as experimental
  cancer therapies using SEQUUS' Doxil product or ALZA's Ethyol product) which
  are not yet widely accepted in the medical community.
 
 . The complex manufacturing processes required for many of the products of
  SEQUUS and ALZA, can cause interruptions in supply, which in turn can have a
  significant negative effect on marketing efforts.
 
Product development efforts may not yield successful products.
 
ALZA's and SEQUUS' future business success will depend on their ability to
successfully develop and obtain regulatory approval to market new
pharmaceutical products. Development of a product requires substantial
technical, financial and human resources even if the product is not
successfully completed. The combination of ALZA and SEQUUS research and
development organizations may result in greater competition for resources and
elimination of development programs that might otherwise be successfully
completed. Due to uncertainties that are part of the development process, many
of the products that we try to develop will not be completed. We may not choose
product candidates that will be successful, we may not be able to execute
development in a timely manner and we may not be able to fully fund development
programs necessary to complete development. Delays or unanticipated increases
in costs of development at any stage of development, or failure of ALZA and
SEQUUS to obtain regulatory approval or market acceptance for their products,
could adversely affect the combined company's operating results.
 
ALZA's and SEQUUS' drug delivery technologies may not be broadly applicable or
may require extensive further investment.
 
The ALZA and SEQUUS drug delivery systems may not perform in the same manner
when different drugs are incorporated into them and therefore these drug
delivery systems may not prove to be as useful or valuable as originally
thought. Substantial funding and other resources may be required to continue
the development of drug delivery systems for use with additional drugs.
 
Special materials must often be manufactured for the first time for use in drug
delivery systems, or materials may be used in the systems in a manner different
from their customary commercial uses. Materials needed for our drug delivery
systems may be difficult to obtain on commercially reasonable terms,
particularly when relatively small quantities are required, or if the materials
traditionally have not been used in pharmaceutical products. Precision and
reproducibility of certain materials are critical to the performance of ALZA
and SEQUUS drug delivery systems, so having reliable sources of materials is
important.
 
Results of clinical trials and approval of products are uncertain and we may be
delayed in or prohibited from selling our products.
 
ALZA and SEQUUS may suffer significant setbacks in advanced clinical trials of
their products, even after obtaining promising results in earlier trials. In
addition, clinical studies may not demonstrate the safety and effectiveness of
a product and even successful completion of clinical trials may not result in
marketable products.
 
Before obtaining regulatory approvals for the sale of any of its products, ALZA
and SEQUUS must demonstrate through preclinical
 
                                       20
<PAGE>
 
studies and clinical trials that the product is safe and effective in each
intended use. The results from preclinical and early clinical studies do not
always accurately predict results in later, large-scale testing.
 
ALZA and SEQUUS each rely on other companies to conduct certain clinical
trials. Those companies may have different interests or priorities than ALZA or
SEQUUS, and their design, timing and conduct of clinical trials may not meet
the objectives of ALZA or SEQUUS. For example, SEQUUS is relying on Schering-
Plough to conduct certain clinical trials for the use of SEQUUS' Doxil(R)
product in treatment of solid tumors. ALZA also works with a number of
pharmaceutical companies who control or share control of clinical development.
 
The rate of patient enrollment sometimes delays completion of clinical studies.
There is substantial competition to enroll patients in clinical trials for
oncology products, and such competition has delayed clinical development of
ALZA and SEQUUS products in the past. Delays in planned patient enrollment can
result in increased development costs and delays in regulatory approval.
 
ALZA's and SEQUUS' operations depend on compliance with complex governmental
regulations.
 
The products that ALZA and SEQUUS develop and sell are subject to extensive
regulation by the United States Food & Drug Administration ("FDA") and
comparable agencies in other countries. These regulations govern a range of
activities including clinical testing, market clearance, manufacturing, quality
assurance, advertising and record-keeping. Failure to obtain, or delays in
obtaining, regulatory clearance to market new products or existing products for
new indications, as well as other regulatory actions and recalls, could
adversely affect our results of operations.
 
Applications for marketing clearance must be based on extensive clinical and
other testing. Requirements for approval may differ from country to country,
and can involve additional testing and additional costs.
 
Substantial delays can occur in obtaining required clearances from both the FDA
and foreign regulatory authorities after applications are filed. Regulatory
authorities may not approve a product for the uses that are proposed by us,
thereby limiting our ability to market the product. Even after clearances are
obtained, further delays may occur before the products become commercially
available in countries requiring pricing approvals.
 
Pharmaceutical pricing and reimbursement pressures may reduce profitability.
 
As pressures for cost containment increase in the United States health care
industry, the prices we can charge for products may be less favorable than in
the past. If one or more of our products is not included on approved drug lists
or is not reimbursed adequately by government agencies or managed care
organizations, our future profitability may be adversely affected.
 
Government and other third-party payors have increased attempts to contain
health care costs by limiting the level of reimbursement for new drugs and
sometimes by refusing to provide coverage or reimbursement for uses of the
products for which the FDA has not granted marketing clearance. Innovative new
products, such as ALZA's Ethyol(R), Elmiron(R), Testoderm(R) TTS or such as
SEQUUS' Doxil and Amphotec(R), may not achieve reimbursement and acceptance on
approved drug lists (called "formularies") sufficient to result in an
appropriate return on the research and development expenses or cost of
acquiring the product.
 
In addition, in many international markets, governments control the prices of
prescription pharmaceuticals. In these markets, once
 
                                       21
<PAGE>
 
marketing approval is received, pricing negotiation can take another 6 to 12
months or longer. We may be forced to lower our prices by competing product
sales, and attempts to gain market share or introductory pricing programs,
which could adversely affect our business, financial condition and results of
operations.
 
ALZA and SEQUUS depend on relationships with other companies for revenues and
access to technologies and failure to maintain these relationships would
negatively impact ALZA and SEQUUS.
 
A significant portion of ALZA's and SEQUUS' net income currently results from
royalties, fees and transfer prices paid by other companies selling products
incorporating ALZA or SEQUUS technologies. These revenues vary from quarter to
quarter as a result of changing levels of product sales by these client
companies. Because the client companies make the decisions regarding
commercializing these products, ALZA and SEQUUS do not directly control most of
the variables that affect these revenues. In addition, these revenues can be
adversely affected by competition and pressures for cost containment on client
companies.
 
ALZA and SEQUUS also rely on relationships with client and other companies for
access to proprietary technology which they need for product development,
including proprietary rights to drugs that may be incorporated into ALZA or
SEQUUS drug delivery systems. Since ALZA and SEQUUS are not engaged in
developing new chemical entities as drugs, their businesses could be adversely
affected if they were unable to continue their access to these proprietary
rights.
 
Uncertainty of supply may affect our ability to produce and sell our products.
 
A number of ALZA and SEQUUS products are made at only one facility. A shutdown
in any of these facilities due to technical, regulatory or other problems,
resulting in an interruption in supply of products, could have an adverse
impact on ALZA's or SEQUUS' financial results.
 
The manufacturing process for pharmaceutical products is highly regulated, and
regulators may shut down manufacturing facilities that they believe do not
comply with regulations. The FDA's current Good Manufacturing Practices are
extensive regulations governing manufacturing processes, stability testing,
record-keeping and quality standards. Similar,
but not identical, regulations are in effect in other countries.
 
SEQUUS' internal manufacturing capabilities are limited to producing products
for preclinical development, and it depends on another company to manufacture
commercial-scale quantities of Amphotec and Doxil. Only a limited number of
contract manufacturers are capable of manufacturing Amphotec and Doxil, and
SEQUUS has in the past experienced difficulties with successful manufacture of
these products. An alternate manufacturer, would require regulatory approval to
manufacture a product, which could take many months to obtain. In the event of
any interruption of supply from a contract manufacturer due to regulatory
reasons, processing problems, capacity constraints or other causes, alternative
manufacturing arrangements may not be available on a timely basis or at an
acceptable price, if at all.
 
An interruption in supply from a supplier of a key material could significantly
delay the manufacturing of one or more ALZA or SEQUUS products. Because the
suppliers of key components and materials must be named in the New Drug
Application ("NDA") filed with the FDA for a product, significant delays can
occur if the qualification of a new supplier is required.
 
                                       22
<PAGE>
 
Patents and intellectual property may be difficult to obtain or ineffective,
allowing other companies to more easily produce products similar to ours.
 
Patent protection generally has been important in the pharmaceutical industry.
We believe that our current patents, and patents that may be obtained in the
future, are important to current operations and will be important in the
future. Our existing patents may not cover future products, additional patents
may not be issued to us, and current patents or patents issued to us in the
future may not provide meaningful protection or prove to be of commercial
benefit. If patent protection is not available, ALZA may face greater
competition or pricing pressures than expected.
 
In the United States, patents are granted for specified periods of time. Some
of ALZA's earlier patents covering various aspects of certain oral and
transdermal dosage forms have expired, or will expire, over the next several
years. In 2003, certain ALZA patents are due to expire that relate to its
OROS(R) systems and the Procardia(R) XL (nifedipine) product (which uses the
OROS delivery system).
 
ALZA commercializes several products it has acquired or in-licensed from other
companies. The extent to which those products are protected by patent rights
varies significantly from product to product. Some products, such as
Ditropan(R) and Mycelex(R) Troche have been sold for many years and are not
covered by patents. Other products may obtain patent protection only for
certain formulations or uses of the product. Additional patents relating to
these products may or may not be issued, or if issued, may not provide
significant proprietary protection for these products.
 
Other companies may successfully challenge our patents in the future. In some
cases, other companies have initiated reexamination by the United States Patent
and Trademark Office of patents issued to ALZA, and have opposed ALZA and
SEQUUS patents in other jurisdictions. Others have also challenged the validity
or enforceability of ALZA patents in litigation. If any challenge is
successful, other companies may then be able to use the invention covered by
the patent without payment.
 
Other companies may try to obtain patents relating to technologies or products
similar to ours. This competitive patent activity may result in adversarial
proceedings such as patent interferences and oppositions, which may result in
third parties obtaining patent positions superior to ours. If other companies
are able to obtain patents that cover any of our technologies or products we
may be subject to liability for damages and our activities could be blocked by
legal action, unless we can obtain licenses to those patents.
 
In addition, ALZA and SEQUUS utilize significant unpatented proprietary
technology and rely on unpatented trade secrets and proprietary know-how to
protect certain aspects of our production and other technologies. Other
companies may develop similar technology to compete with ALZA and/or SEQUUS.
 
ALZA and SEQUUS face intense competition from other companies whose products
may gain greater market acceptance than ours.
 
Most or all of the products commercialized by ALZA and SEQUUS will face
competition from different chemical or other agents intended for treatment of
the same diseases. In addition, our current and future products are likely to
face competition both from traditional forms of drug delivery and from advanced
delivery systems being developed by others. A large number of companies are
developing drug
 
                                       23
<PAGE>
 
delivery technologies. Competitors could include any of the pharmaceutical
companies in the world, including companies for which ALZA has developed
products. Many of these pharmaceutical companies have greater financial
resources, technical staff and manufacturing and marketing capabilities than we
do. To the extent that we develop or market products incorporating drugs that
are not covered by patents, or products that are being developed by multiple
companies, we are likely to face competition from other companies developing
and marketing similar products.
 
Other pharmaceutical companies are aggressively seeking to obtain new products
by licensing technology from other companies. We will be competing to license
or acquire technology with companies with far greater financial and other
resources than ours.
 
Generic pharmaceutical manufacturers will increase competition for certain
products. Generic competitors generally are able to obtain regulatory approval
for drugs no longer covered by patents without investing in costly and time-
consuming clinical trials, and need only demonstrate that their product is
equivalent to the drug they wish to copy. Because of their substantially
reduced development costs, generic companies are often able to charge much
lower prices for their products than the originator of a new product. Several
generic companies have filed for approval to market generic versions of the
ALZA-developed Procardia XL product. The introduction of generic competition
could significantly reduce ALZA's royalties from this product. A number of ALZA
and SEQUUS products incorporate chemical entities that are not covered by
patents. These products may be subject to competition from generic drugs.
 
Product liability claims may increase costs and decrease profits.
 
Testing, manufacturing, marketing and use of ALZA's and SEQUUS' pharmaceutical
products involve substantial risk of product liability claims. In the past,
product liability exposure has been modest and ALZA has been indemnified by
client companies who market products developed by ALZA. However, due to the
expansion of ALZA's marketing and sales activities and increased sales of
products marketed directly by ALZA, the exposure to product liability claims
may increase significantly. Although we maintain product liability insurance, a
single product liability claim could exceed our coverage limits, and multiple
claims are possible. If that happens, the insurance coverage we have may not be
adequate, and in the future such insurance may not be renewed at an acceptable
cost or at all. Our business, financial condition and results of operations
could be materially and adversely affected by one or more successful product
liability claims.
 
 
                                       24
<PAGE>
 
                              The Special Meeting
 
SEQUUS will hold the special meeting on March 16, 1999, at 10:00 a.m., local
time, at its corporate offices at 960 Hamilton Court, Menlo Park, California.
This proxy statement/prospectus is being used to solicit proxies from the
stockholders of SEQUUS by the board of directors of SEQUUS for use at the
special meeting.
 
This proxy statement/prospectus and the accompanying forms of proxies are first
being mailed to SEQUUS stockholders on or about February 12, 1999.
 
Matters to Be Considered at the Special Meeting; Recommendation of the SEQUUS
Board
 
At the special meeting, holders of SEQUUS common stock as of the record date
(which is  January 19, 1999) will consider and vote upon the approval and
adoption of the merger agreement providing for the merger. As a result of the
merger, each outstanding share of SEQUUS common stock would be converted into
the right to receive 0.40 of a share of ALZA common stock and SEQUUS would
become a wholly-owned subsidiary of ALZA.
 
The SEQUUS Board has unanimously approved the merger agreement and recommended
a vote FOR approval and adoption of the merger agreement by the SEQUUS
stockholders.
 
Record Date and Quorum
 
The SEQUUS Board has fixed January 19, 1999 as the record date for the
determination of the SEQUUS stockholders entitled to notice of and to vote at
the special meeting. Accordingly, only holders of record of shares of SEQUUS
common stock on the record date will be entitled to notice of and to vote at
the special meeting. As of the record date there were 32,627,715 shares of
SEQUUS common stock outstanding and entitled to vote and held by 332 holders of
record. Each holder of record of SEQUUS common stock on the record date is
entitled to cast one vote per share, either in person or by properly executed
proxy, on each proposal properly submitted for the vote of the SEQUUS
stockholders at the special meeting. The presence, in person or by properly
executed proxy, of the holders of a majority of the outstanding shares of
SEQUUS common stock entitled to vote is necessary to constitute a quorum at the
special meeting.
 
Required Vote
 
The approval and adoption by SEQUUS stockholders of the merger agreement will
require the affirmative vote of the holders of a majority of the outstanding
shares of SEQUUS common stock entitled to vote on the merger. A failure to vote
or an abstention or a broker non-vote will have the same legal effect as a vote
by a SEQUUS stockholder against the approval and adoption of the merger
agreement and against the approval of the merger.
 
Each SEQUUS director, in his or her capacity as a stockholder, has agreed at
the time of the special meeting to vote or direct the vote of all shares of
SEQUUS common stock over which he or she has voting control FOR approval and
adoption of the merger agreement pursuant to the terms of voting agreements
entered into between ALZA and each director at the time of the execution of the
merger agreement. Directors of SEQUUS beneficially own approximately 3% of the
shares of SEQUUS
 
                                       25
<PAGE>
 
common stock outstanding as of the record date. See "The Merger Agreement and
the Related Agreements--The Voting Agreements."
 
As of the date of this proxy statement/prospectus, neither ALZA nor any of its
subsidiaries owned any shares of SEQUUS common stock.
 
Proxies
 
This proxy statement/prospectus is being furnished to SEQUUS stockholders in
connection with the solicitation of proxies from the SEQUUS stockholders for
use at the special meeting.
 
All shares of SEQUUS common stock that are entitled to vote and represented at
the special meeting by properly executed proxies received prior to or at the
special meeting, and not revoked, will be voted at the special meeting in
accordance with the instructions indicated on the proxies. If no instructions
are indicated, the proxies will be voted FOR approval of the merger and
approval and adoption of the merger agreement.
 
If any other matters are properly presented at the special meeting for
consideration, including consideration of a motion to adjourn the special
meeting to another time and/or place (including for the purpose of soliciting
additional proxies), unless the stockholder otherwise indicates, the persons
named on the enclosed form of proxy will have the discretion to vote on such
matters in accordance with his or her best judgment.
 
A proxy may be revoked by the person who gave it at any time before it is
voted. Proxies may be revoked by:
 
  . filing with the Corporate Secretary of SEQUUS, at or before the taking of
    the vote at the special meeting, a written notice of revocation bearing a
    later date than the proxy;
 
  . executing a later-dated proxy relating to the same shares and delivering
    it to the Corporate Secretary of SEQUUS before the taking of the vote at
    the special meeting; or
 
  . attending the special meeting and voting in person (although attendance
    at the special meeting will not in and of itself constitute a revocation
    of the proxy).
 
Any written notice of revocation or subsequent proxy should be sent so as to be
delivered to Sally A. Davenport, Corporate Secretary, SEQUUS Pharmaceuticals,
Inc., 960 Hamilton Court, Menlo Park, California 94025, or hand-delivered to
the Corporate Secretary of SEQUUS, at or before the taking of the vote at the
special meeting.
 
Solicitation of Proxies
 
The entire cost of soliciting the proxies from SEQUUS stockholders will be
borne by SEQUUS, except that ALZA and SEQUUS have each agreed to pay one half
of the printing and mailing costs associated with this proxy
statement/prospectus. See "The Merger Agreement and the Related Agreements--
Fees, Expenses and Termination Fees." SEQUUS will also request banks, brokers
and other record holders to send proxies and proxy materials to the beneficial
owners of its common stock and secure their voting instructions, if necessary.
SEQUUS will reimburse such record holders
 
                                       26
<PAGE>
 
for their reasonable expenses in so doing. Proxies may also be solicited
personally or by telephone or other means of communication by directors,
officers and regular employees of SEQUUS without additional compensation
therefor.
 
Independent Auditors
 
One or more representatives of Ernst & Young LLP, independent auditors for
SEQUUS, are expected to be present at the special meeting and will have an
opportunity to make a statement if they desire to do so and will be available
to respond to appropriate questions.
 
                 SEQUUS STOCKHOLDERS SHOULD NOT SEND ANY STOCK
                      CERTIFICATES WITH THEIR PROXY CARDS.
 
 
                                       27
<PAGE>
 
                                   The Merger
 
Background of the Merger
 
For a number of years, SEQUUS has believed that entering into beneficial
alliances with significant partners would be important in supporting and
leveraging its marketing and research and development efforts.
 
Beginning in May 1996, SEQUUS and ALZA had discussions regarding a potential
arrangement for the licensing of two SEQUUS products, Amphotec and Doxil, to
ALZA. Those discussions involved Dr. Ernest Mario, then Co-Chairman and Chief
Executive Officer of ALZA, Dr. I. Craig Henderson, the Chairman and Chief
Executive Officer of SEQUUS, and other senior members of the ALZA and SEQUUS
management teams. In the course of these discussions, SEQUUS and ALZA entered
into a Confidentiality and Standstill Agreement. These discussions terminated
near the end of October 1996 and did not result in any business relationship
between the two companies.
 
In October 1997, Dr. Henderson received a letter from Dr. Mario outlining a
proposed arrangement whereby ALZA would acquire from SEQUUS marketing rights to
Doxil in the United States and Canada. After due consideration by the SEQUUS
Board, this proposal was rejected by SEQUUS.
 
On August 13, 1998, Dr. Joseph Vallner, the Chief Operating Officer of SEQUUS,
received a telephone call from Dr. Mario of ALZA. Dr. Mario proposed a meeting
with Dr. Vallner.
 
On the morning of August 26, 1998, Dr. Vallner and Mr. John Richard, the
Executive Vice President for Business Development of SEQUUS, met with Dr. Mario
and Mr. Robert Myers, the Vice President of Commercial Development of ALZA. Dr.
Mario and Mr. Myers informed Dr. Vallner and Mr. Richard that ALZA was
impressed with the potential of SEQUUS' products, programs and personnel. They
also indicated that they believed that a business combination of ALZA and
SEQUUS would allow the two companies to take maximum advantage of their
complementary programs in oncology and drug delivery, and would provide
significant strategic and financial value to the stockholders of both
companies.
 
In a letter to Dr. Henderson dated August 26, 1998, Dr. Mario confirmed the
content of the discussions held earlier that day and indicated that ALZA was
prepared to enter into serious negotiations regarding a business combination of
SEQUUS with ALZA. Following the receipt of that letter, SEQUUS commenced the
process of identifying and selecting a financial advisor and special counsel to
represent it in the evaluation of ALZA's proposal.
 
On August 30, 1998, the SEQUUS Board held a telephonic board meeting in which
the letter from ALZA was discussed, and authorized SEQUUS management to engage
legal and financial advisors to assist in SEQUUS' evaluation of ALZA's
proposal. Following that meeting SEQUUS engaged Cooley Godward llp as special
counsel.
 
On August 31, 1998, SEQUUS contacted Credit Suisse First Boston Corporation
("CSFB") and requested that CSFB provide financial advice to SEQUUS regarding
ALZA's proposal. CSFB began providing financial advice to SEQUUS regarding the
proposal by ALZA, and a formal engagement agreement was entered into between
SEQUUS and CSFB on September 11, 1998.
 
                                       28
<PAGE>
 
At and prior to the time ALZA submitted its proposal to SEQUUS, SEQUUS had been
exploring business opportunities with another major pharmaceutical company
involving an investment in SEQUUS. These discussions resulted in a letter of
intent between SEQUUS and the other pharmaceutical company and negotiations
during the month of August 1998. These negotiations did not result in a
definitive agreement between SEQUUS and the other pharmaceutical company prior
to the expiration of the letter of intent, and the negotiations were placed on
hold by SEQUUS to allow SEQUUS to evaluate the ALZA proposal. SEQUUS and the
other pharmaceutical company held subsequent discussions regarding various
business opportunities during the month of September 1998. These subsequent
discussions did not result in any proposals or potential arrangements that the
SEQUUS Board determined would be as advantageous to SEQUUS and its stockholders
as the ALZA proposal.
 
On September 1, 1998, Dr. Henderson met with Dr. Mario to discuss the proposal
contained in Dr. Mario's August 26, 1998 letter. Dr. Henderson informed Dr.
Mario that SEQUUS would submit the proposal to the SEQUUS Board for
consideration at its next scheduled meeting on September 14 and 15, 1998.
 
On September 14 and 15, 1998, the SEQUUS Board held a regularly scheduled
SEQUUS Board meeting. At this meeting, the SEQUUS Board discussed the ALZA
proposal and asked SEQUUS management to pursue clarification and improvement of
certain aspects of ALZA's proposal. Advisors from Cooley Godward, CSFB and
Ernst & Young llp, SEQUUS' independent auditors, were present during
discussions of the ALZA proposal and participated in the discussions.
 
SEQUUS management subsequently received a revised proposal from ALZA and
reviewed such proposal with the SEQUUS Board during a telephonic meeting of the
SEQUUS Board held on September 16, 1998. Based upon the revised proposal, the
SEQUUS Board authorized management to proceed with discussions regarding such
proposal and commence negotiation of a definitive agreement with ALZA.
 
On September 17, 1998, SEQUUS and ALZA entered into confidentiality agreements
with each other and on September 17 and 18, 1998, SEQUUS management made
presentations regarding its business to senior members of ALZA management as
well as financial and legal advisors of ALZA.
 
On September 22, 1998, ALZA management made presentations regarding its
business to senior members of SEQUUS management as well as financial and legal
advisors of SEQUUS.
 
Throughout the remainder of September, ALZA and SEQUUS completed their reviews
regarding each other's business, while the two companies continued the
negotiation of a definitive agreement with the assistance of their legal and
financial advisors. On September 26 and October 1, 1998, the SEQUUS Board held
telephonic meetings during which the status of the negotiations between SEQUUS
and ALZA was discussed.
 
On October 2 and 3, 1998, senior management of SEQUUS and ALZA and their
respective financial and legal advisors held meetings to negotiate and finalize
the terms of the proposed definitive merger agreement.
 
                                       29
<PAGE>
 
At a meeting held on October 4, 1998, CSFB, Cooley Godward and Ernst & Young
gave presentations to the SEQUUS Board. After a review and discussion of the
terms of the proposed merger agreement, and discussions regarding the financial
and other effects the proposed merger would have on SEQUUS stockholders, the
SEQUUS Board unanimously approved the merger and authorized the officers of
SEQUUS to finalize and execute the merger agreement.
 
The definitive merger agreement was executed on behalf of ALZA, SEQUUS and
Merger Sub on October 4, 1998.
 
SEQUUS' Reasons for the Merger
 
The SEQUUS Board has approved the merger agreement, believes that the merger is
fair to and in the best interests of SEQUUS and its stockholders, and
unanimously recommends the approval and adoption of the merger agreement by the
SEQUUS stockholders at the special meeting.
 
In the course of reaching its decision to approve the merger agreement, the
SEQUUS Board considered and reviewed with SEQUUS management a number of factors
relevant to the merger, including the strategic overview and prospects of
SEQUUS, its products and its finances. The SEQUUS Board also considered, among
other matters:
 
 . the SEQUUS Board's view that the merger should result in a combined
  biopharmaceutical and drug development company with:
 
 -- substantially greater resources than SEQUUS as a stand-alone company,
 -- a more diversified product base than that of SEQUUS as a stand-alone
    company and
 -- an enhanced development pipeline, enhanced sales performance, an expanded
    distribution network and manufacturing capability, and a broader
    international presence;
 
 . the SEQUUS Board's view that ALZA's greater financial resources will allow it
  to supply appropriate levels of capital and other resources to pursue
  research and development programs in oncology using SEQUUS technology;
 
 . the SEQUUS Board's view that ALZA's strengths in the testing, registration
  and manufacture of pharmaceutical products and drug delivery technologies
  will complement SEQUUS' own strengths in the research and development of
  oncological pharmaceuticals, allowing the combined company to more
  efficiently bring products to market;
 
 . the SEQUUS Board's view that the merger will combine SEQUUS' primary product
  area with a key therapeutic focus of ALZA;
 
 . the SEQUUS Board's view that the merger will enable the companies to combine
  their respective research and development programs and should thereby enable
  the companies to achieve greater diversification and operating synergies;
 
 . the SEQUUS Board's view that the combination of SEQUUS' STEALTH(TM) liposome
  technology with ALZA's existing drug delivery platforms (including OROS(R),
  D-TRANS(TM), E-TRANS(TM) and DUROS(TM)) should significantly enhance the
  combined companies' overall drug delivery capabilities;
 
                                       30
<PAGE>
 
 . the status of SEQUUS' current research collaborations and other commercial
  relationships;
 
 . the SEQUUS Board's assessment of SEQUUS' strategic alternatives to the
  merger, including remaining an independent company, licensing or otherwise
  transferring its rights to future discoveries, and merging or consolidating
  with a party other than ALZA or acquiring other companies;
 
 . information regarding historical market prices and other information with
  respect to the SEQUUS common stock and ALZA common stock, and the financial
  performance and condition, assets, liabilities, business operations, and
  prospects of each of SEQUUS and ALZA and their projected future values and
  prospects as separate entities and on a combined basis;
 
 . the presentation delivered by CSFB to the SEQUUS Board and the written
  opinion of CSFB addressed to the SEQUUS Board to the effect that as of the
  date of the opinion and based on and subject to the matters set forth in the
  opinion, the exchange ratio was fair, from a financial point of view, to the
  SEQUUS stockholders;
 
 . the consideration to be received by SEQUUS stockholders in the merger and the
  fact that the market value of the ALZA common stock to be issued in exchange
  for each share of SEQUUS common stock represented a significant premium over
  the recent price range of the SEQUUS common stock (the merger consideration
  represented a premium of approximately 66.0%, 92.3% and 58.7% over the
  average price of the SEQUUS common stock for the ten-day, one-month and one-
  year period, respectively, ending October 1, 1998);
 
 . the compatibility of management of the two companies;
 
 . a comparison of selected recent acquisition and merger transactions in the
  industry as well as trading performance for comparable companies in the
  industry;
 
 . the belief that the terms of the merger agreement, including the parties'
  mutual representations, warranties and covenants, are reasonable and the fact
  that the merger agreement did not contain any extraordinary conditions to
  ALZA's obligations to consummate the merger;
 
 . the ability of the SEQUUS Board to enter into discussions with a person or
  entity in response to an unsolicited proposal to purchase SEQUUS which, among
  other things, the SEQUUS Board determines in good faith, after consultation
  with its outside legal counsel, that failure to participate in discussions
  with that person or entity would violate the SEQUUS Board's fiduciary duties;
 
 . the expected tax and accounting treatment of the merger; and
 
 . reports from management, financial advisors and legal advisors as to the
  results of their investigation of ALZA.
 
The SEQUUS Board also considered a number of potentially negative factors in
its deliberations concerning the merger, including, but not limited to:
 
 . the loss of control over the future operations of SEQUUS following the
  merger;
 
 . the risk that the benefits sought to be achieved in the merger will not be
  achieved;
 
                                       31
<PAGE>
 
 . risks associated with product development and approval, including ALZA's
  pending application for approval of Ditropan XL;
 
 . the fixed nature of the exchange ratio and the resulting risk that, should
  there be a decrease in the market value of ALZA common stock, the value of
  the consideration to be received by SEQUUS stockholders would be reduced; and
 
 .the other risks described above under "Risk Factors."
 
The SEQUUS Board discussed with management the prospects for combinations with
companies other than ALZA, the possibility that the benefits described above or
other benefits could be achieved through any other combinations and the risks
and benefits of a stand-alone strategy.
 
This discussion of information and factors considered by the SEQUUS Board is
not intended to be exhaustive but is believed to include all material factors
considered by the SEQUUS Board. In view of the wide variety of factors
considered by the SEQUUS Board, the SEQUUS Board did not find it practicable to
quantify or otherwise assign relative weight to the specific factors
considered. However, after taking into account all of the factors set forth
above, the SEQUUS Board unanimously agreed that the merger agreement and the
consummation of the merger were fair to, and in the best interests of, SEQUUS
and its stockholders and that SEQUUS should enter into the merger agreement.
 
Opinion of SEQUUS' Financial Advisor
 
SEQUUS retained CSFB to act as its financial advisor in connection with the
merger based upon CSFB's experience, expertise and knowledge of SEQUUS from
prior interactions. CSFB delivered to the SEQUUS Board its written opinion,
dated October 4, 1998, that, based upon and subject to the factors and
assumptions set forth in the fairness opinion, as of the date of the opinion,
the exchange ratio was fair from a financial point of view to the holders of
SEQUUS common stock. SEQUUS determined the exchange ratio following arm's-
length negotiations with ALZA and determined that the exchange ratio was fair
and in the best interest of its stockholders. These determinations were based
on many factors, including those discussed under the heading "SEQUUS' Reasons
for the Merger" and including the opinion of CSFB that the exchange ratio was
fair to the stockholders from a financial point of view.
 
The summary of the CSFB opinion described in this proxy statement/prospectus is
qualified in its entirety by reference to the full text of the CSFB opinion.
The opinion explains the procedures followed, assumptions and qualifications
made, matters considered and limitations on the review undertaken by CSFB. The
full text of the CSFB opinion, which has been used in this proxy
statement/prospectus with the consent of CSFB, is attached as Annex C to this
proxy statement/prospectus and is incorporated in this summary by reference.
Stockholders of SEQUUS are urged to read the CSFB opinion carefully and in its
entirety. The CSFB opinion was provided to the SEQUUS Board for its information
in connection with its consideration of the merger and is not a recommendation
to any stockholder as to how the stockholder should vote on the proposed
merger.
 
In preparing the CSFB opinion, CSFB performed a variety of financial and
comparative analyses, including those described below. The following summary of
CSFB's analyses is not a complete
 
                                       32
<PAGE>
 
description of the analyses underlying the CSFB opinion or the presentation
made by CSFB to the SEQUUS Board. The preparation of a fairness opinion is a
complex analytic process involving various determinations as to the most
appropriate and relevant methods of financial analyses and the application of
those methods to the particular circumstances, and, therefore, it is inherently
difficult to partially analyze or summarily describe the fairness opinion. In
arriving at its opinion, CSFB did not attribute any particular weight to any
analysis or factor considered by it, but rather made qualitative judgments
about the significance and relevance of each analysis and factor. Accordingly,
CSFB believes that its analyses must be considered as a whole and that
selecting portions of its analyses, without considering all analyses, would
create an incomplete view of the process underlying its opinion.
 
In performing its analyses, CSFB made numerous assumptions with respect to
SEQUUS, ALZA, industry performance, general business, economic, market and
financial conditions and other matters, many of which are beyond the control of
SEQUUS or ALZA. No company, transaction or business used in those analyses as a
comparison is identical to SEQUUS, ALZA or the proposed merger, nor is an
evaluation of the results of the analyses entirely mathematical; rather, the
analyses involve complex considerations and judgments concerning financial and
operating characteristics and other factors that could affect the acquisition,
public trading or other values of the companies, business segments or
transactions being analyzed. Any estimates contained in the analyses performed
by CSFB do not necessarily indicate actual values or future results, which may
be significantly more or less favorable than suggested by the analyses.
Additionally, estimates of the value of businesses or securities are not
appraisals and do not reflect the prices at which those businesses or
securities might actually be sold. Accordingly, the analyses and estimates
described above are inherently subject to substantial uncertainty. In addition,
the CSFB opinion and CSFB's presentation to the SEQUUS Board were among several
factors taken into consideration by the SEQUUS Board in making its
determination to approve the merger. Consequently, the CSFB analyses described
below should not be viewed as, and were not, determinative of the opinion of
the SEQUUS Board or SEQUUS management with respect to the exchange ratio or the
proposed merger.
 
In arriving at its opinion, CSFB reviewed certain publicly available business
and financial information relating to SEQUUS and ALZA, as well as a draft of
the merger agreement. CSFB also reviewed certain other information, including
financial forecasts, provided to it by SEQUUS and ALZA, and met with SEQUUS and
ALZA management to discuss the business and prospects of SEQUUS and ALZA.
 
CSFB also considered certain financial and stock market data of SEQUUS and
ALZA, and compared that data with similar data for other publicly-held
companies in businesses similar to SEQUUS and ALZA and considered the financial
terms of certain other business combinations and other transactions which have
recently been effected. CSFB also considered other information, financial
studies, analyses and investigations and financial, economic and market
criteria which it deemed relevant.
 
In connection with its review, CSFB did not assume any responsibility for
independent verification of any of the information described above and relied
on it being complete and accurate in all material respects. With respect to the
financial forecasts, CSFB assumed that they were reasonably prepared on bases
reflecting the best currently available estimates and judgments of SEQUUS and
ALZA
 
                                       33
<PAGE>
 
management as to the future financial performance of the company anticipated to
result from the merger. In addition, CSFB was not requested to make, and did
not make, an independent evaluation or appraisal of the assets or liabilities
(contingent or otherwise) of SEQUUS or ALZA, nor was it furnished with any
evaluations or appraisals. The CSFB opinion is necessarily based on financial,
economic, market and other conditions as they existed and could be evaluated on
the date the opinion was given. CSFB did not express any opinion as to the
actual value of the ALZA common stock when issued to SEQUUS stockholders
pursuant to the merger or the prices at which the ALZA common stock will trade
subsequent to the merger. CSFB was not requested to, and did not, solicit
third-party indications of interest in acquiring all or any part of SEQUUS.
 
The following is a summary of the analyses performed by CSFB in connection with
the preparation of the CSFB Opinion. The summary of the analyses includes
information presented in tabular format. In order to fully understand the
analyses, the tables should be read together with the text of each summary.
Consideration of the tables alone without the full narrative description of the
analyses, including the underlying assumptions, would create a misleading or
incomplete view of the process underlying, and conclusions represented by, the
CSFB opinion.
 
Comparative Stock Price Performance Analysis. CSFB reviewed the per share daily
closing prices of SEQUUS common stock over the twelve-month period ending
October 1, 1998 compared with the performance of other drug delivery companies,
including NeXstar Pharmaceuticals, Inc. and The Liposome Company, and compared
with relevant market indices including the Russell 2000 and the NASDAQ Biotech
Index. CSFB reviewed the per share daily closing prices of ALZA common stock
over the twelve-month period ending October 1, 1998 compared with the
performance of other biopharmaceutical companies including Elan Corporation and
compared with relevant market indices including the Russell 2000, the NASDAQ
Biotech Index and the S&P 400. CSFB also reviewed the ratios of SEQUUS' to
ALZA's per share daily closing stock prices for the twelve-month period ending
October 1, 1998, as well as the closing stock prices on October 1, 1998, and
computed the premium or discount of the exchange ratio in relation to the
prices mentioned above. The following table presents the ratios of the various
stock prices of SEQUUS to ALZA over selected periods, and the premium that the
exchange ratio represented over those ratios.
 
<TABLE>
<CAPTION>
                                                           Ratio of     Exchange
   Period Ending                                          SEQUUS to      Ratio
   October 1, 1998                                     ALZA Stock Price Premium
   ---------------                                     ---------------- --------
   <S>                                                 <C>              <C>
    10 day............................................      0.241         66.0%
    1 month...........................................      0.208         92.3
    1 year............................................      0.252         58.7
</TABLE>
 
SEQUUS Discounted Cash Flow Analyses. CSFB performed discounted cash flow
analyses for fiscal years 1998 to 2007 to estimate the present value of the
stand-alone unlevered free cash flows that SEQUUS is expected to generate if
SEQUUS performs in accordance with scenarios based on financial forecasts
discussed below. For purposes of these analyses, unlevered free cash flows were
 
                                       34
<PAGE>
 
defined as unlevered net income plus depreciation plus amortization less
capital expenditures less investment in working capital.
 
CSFB performed its analyses based on management projections provided to it by
SEQUUS for three separate business scenarios: a SEQUUS base case, a SEQUUS
upside case and a SEQUUS downside case. The SEQUUS base case reflects SEQUUS'
current business plan, including SEQUUS management forecasts for fiscal years
1998 through 2007. The SEQUUS upside case is similar to the SEQUUS base case,
but assumes faster revenue growth for Doxil/Caelyx and SPI-077. The SEQUUS
downside case is similar to the SEQUUS base case, but assumes SPI-077 is not
approved by the FDA for marketing.
 
The SEQUUS base case projections were based on several significant assumptions:
 
  . Strong growth in Doxil/Caelyx was assumed due to increased use of the
    product in treating solid tumors (e.g., ovarian and breast cancer).
 
  . SPI-077 was assumed to be introduced in 2001.
 
  . Amphotec/Amphocil sales growth was assumed to be modest.
 
  . Minimal sales of radiosensitizers were assumed.
 
  . Terminal value multiples of unlevered net income and EBITDA of 18x to 24x
    and 8x to 14x, respectively, were assumed. This range is based on
    multiples of more mature biotech companies that currently trade at those
    multiples. CSFB also took into account the relative growth rate of SEQUUS
    relative to that group.
 
In computing the terminal value using perpetuity growth rates, CSFB used a
range of growth rates from 6.0% to 12.0%.
 
The SEQUUS upside case is similar to the SEQUUS base case except that the model
assumes stronger sales growth for Doxil/Caelyx and SPI-077. Terminal value
multiples of unlevered net income and EBITDA are the same as those used in the
SEQUUS base case. In computing the terminal value using perpetuity growth
rates, CSFB used a slightly higher range of growth rates from 8.0% to 14.0% to
reflect higher overall growth assumptions.
 
The SEQUUS downside case assumes exactly the same sales for all products as the
SEQUUS base case, except that this case assumes SPI-077 is not approved by the
FDA and is not brought to market over the projection period. CSFB assumed lower
terminal value multiples of unlevered net income of 10x to 16x and lower
terminal value multiples of EBITDA of 6x to 12x. This reflects the lower
overall growth of SEQUUS without SPI-077. Lower perpetuity growth rates were
used under this case, ranging from (3.0)% to 3.0%.
 
For all of the cases, the unlevered free cash flow streams were discounted
using an increasing discount rate beginning at 12.0% in 1998 and increasing by
1.0% per year through 2007. An increasing discount rate was used to reflect the
increasing uncertainty of cash flows beyond the next year. CSFB uses this
technique in valuing the cash flows from biotech companies. Terminal values
were discounted at rates ranging from 17.5% to 32.5%. The following table
presents the implied equity values per diluted share for SEQUUS based on the
SEQUUS discounted cash flow analyses.
 
                                       35
<PAGE>
 
<TABLE>
<CAPTION>
                                                                  Implied SEQUUS
                                                                   Equity Value
                                                                       Per
                                                                  Diluted Share
                                                                  --------------
   <S>                                                            <C>
   SEQUUS Downside Case..........................................  $ 5.14- 6.52
   SEQUUS Base Case..............................................   14.06-18.18
   SEQUUS Upside Case............................................   19.55-22.29
</TABLE>
 
CSFB also separately valued the potential synergies resulting from the merger.
Projections were made for two separate scenarios, a conservative synergies case
and an aggressive synergies case. For the conservative synergies case, CSFB
assumed that, after the merger:
 
  . SEQUUS' expenses which are not directly attributable to a specific
    product (unallocated expenses) would be decreased by 80%;
 
  . sales and marketing expenses would be decreased by 25%;
 
  . and research and development expenses would be decreased by 15%.
 
For the aggressive synergies case, CSFB assumed that, after the merger:
 
  . SEQUUS' unallocated expenses would be decreased by 80%;
 
  . sales and marketing expenses would be decreased by 50%; and
 
  . research and development expenses would be decreased by 15%.
 
The unlevered free cash flow streams were then discounted using an increasing
discount rate beginning at 8.0% in 1998 and increasing 0.5% per year through
2007. Terminal values were discounted at rates ranging from 13.0% to 15.0%. The
following table presents the implied equity values of the synergies per diluted
share of SEQUUS common stock based on the discounted cash flow analyses of
potential synergies resulting from the merger.
 
<TABLE>
<CAPTION>
                                                         Implied Equity Value of
                                                          Synergies Per Diluted
                                                              SEQUUS Share
                                                         -----------------------
   <S>                                                   <C>
   Conservative Synergies Case..........................      $10.29-13.03
   Aggressive Synergies Case............................       13.72-16.46
</TABLE>
 
ALZA Discounted Cash Flow Analyses. CSFB performed discounted cash flow
analyses for fiscal years 1998 to 2004 to estimate the present value of the
stand-alone unlevered free cash flows that ALZA is expected to generate if ALZA
performs in accordance with scenarios based on specific financial forecasts.
CSFB performed a valuation of ALZA because holders of SEQUUS common stock will
be receiving ALZA common stock in the merger. For purposes of this analysis,
unlevered free cash flows were defined as unlevered net income plus
depreciation plus amortization less capital expenditures less investment in
working capital.
 
 
                                       36
<PAGE>
 
CSFB performed its analyses based on publicly available research and CSFB's due
diligence review with ALZA management for two separate business scenarios: an
ALZA base case and an ALZA conservative case.
 
The ALZA base case was based on averages of publicly available equity research
estimates, which assumed strong growth in Ditropan XL and other key products
such as DUROS(R) leuprolide and OROS(R) methylphenidate, and the review with
ALZA management. CSFB used terminal value multiples of unlevered net income of
18x to 24x and terminal value multiples of EBITDA of 8x to 14x, which is in
line with the multiples of other mature biopharmaceutical companies. In
computing the terminal value using perpetuity growth rates, CSFB used growth
rates ranging from 4.0% to 7.0%, reflecting the slightly lower growth rate of
ALZA relative to SEQUUS.
 
The assumptions underlying the ALZA conservative case are identical to those
underlying the ALZA base case with the exception that CSFB assumed Ditropan XL
would not receive FDA approval and therefore no sales from this product are
included in the projections. The ALZA conservative case served as a sensitivity
case for the ALZA base case.
 
For both of the models, the unlevered free cash flow streams were then
discounted using an increasing discount rate beginning at 10.0% in 1998 and
increasing 0.5% per year through 2004. As with the discount rate used in the
SEQUUS analysis, an increasing discount rate was used to reflect the increasing
uncertainty of cash flows beyond the next year. Terminal values were discounted
at rates ranging from 15.0% to 18.0%. The following table presents the implied
equity values per diluted share for ALZA based on the ALZA discounted cash flow
analyses.
 
<TABLE>
<CAPTION>
                                                                   Implied ALZA
                                                                   Equity Value
                                                                   Per Diluted
                                                                      Share
                                                                   ------------
     <S>                                                           <C>
     ALZA Base Case............................................... $38.12-49.00
     ALZA Conservative Case.......................................  32.82-39.29
</TABLE>
 
To provide a further test of the ALZA conservative case as a sensitivity case,
CSFB also estimated the stock price of ALZA without Ditropan XL approval using
a price to earnings to growth analysis. Assuming a drop in ALZA's long-term
growth rate from 23.0% to 18.8% and a constant ratio of price to earnings to
growth, and using the ALZA conservative case earnings per share amounts for
1999 and 2000, CSFB calculated a range of equity values equivalent to the low
end of the value range for the ALZA conservative case.
 
SEQUUS Comparable Companies Analysis. Using publicly available information,
CSFB compared selected financial, operating and stock market data for SEQUUS to
corresponding data of comparable drug delivery companies, including:
 
      . NeXstar Pharmaceuticals, Inc.             . ANDRX Corporation
      . The Liposome Company                      . Alkermes, Inc.
      . Elan Corporation                          . Biovail Corporation
      . Fuisz Technologies Ltd.
 
 
                                       37
<PAGE>
 
CSFB noted that its discounted cash flow analysis was a more appropriate
valuation technique for SEQUUS than the comparable companies analysis because
it is difficult to assign multiples to SEQUUS since it is not yet profitable.
CSFB noted that SEQUUS' revenue multiple is the only meaningful multiple for a
comparable analysis but revenue multiples are a poor proxy for valuation
purposes, because most companies trade off earnings (when they generate
earnings). The following table presents the valuation range for SEQUUS common
stock based on the SEQUUS comparable companies analysis.
 
<TABLE>
<CAPTION>
                                                                 Valuation Range
                                                                  Per Share of
                                                                  SEQUUS Common
                                                                      Stock
                                                                 ---------------
     <S>                                                         <C>
     Comparable Companies Analysis..............................   $7.20-9.26
</TABLE>
 
ALZA Comparable Companies Analysis. Using publicly available information, CSFB
compared selected financial, operating and stock market data for ALZA to
corresponding data of the same comparable companies. CSFB focused its analysis
on Elan Corporation, the company that CSFB identified as most comparable to
ALZA. ALZA currently trades in line with Elan Corporation based on both a price
to earnings multiple and a price to earnings to growth rate basis. CSFB arrived
at a valuation range of $38.21 to $49.00 per share of ALZA common stock based
on the comparable companies analysis. The following table presents the
valuation range for ALZA common stock based on the ALZA comparable companies
analysis.
 
<TABLE>
<CAPTION>
                                                                 Valuation Range
                                                                  Per Share of
                                                                      ALZA
                                                                  Common Stock
                                                                 ---------------
     <S>                                                         <C>
     Comparable Companies Analysis..............................  $38.21-49.00
</TABLE>
 
Comparable Acquisitions Analysis. CSFB reviewed all relevant transactions in
the drug delivery/biotech industry during 1996 and 1997 and through September
of 1998 to determine the relative prices paid in comparable transactions.
Because many of the companies acquired in this industry were not profitable,
CSFB was unable to ascertain exact acquisition multiples, but multiples were
determined within a reasonable range for the limited data CSFB could obtain
from the transactions. More information was available with respect to
acquisition premiums paid over the target's stock price one day, seven days and
one month prior to the announcement of a transaction. The following table
presents the mean premium for the comparable transactions compared with the
premium that would be paid in this merger.
 
<TABLE>
<CAPTION>
                                                           Mean Premium
                                                            Paid Over
       Period Prior                                       Target's Stock
         to the                                              Price--     Premium
     Announcement of                                        Comparable   in This
      the Transaction                                      Transactions  Merger
     ----------------                                     -------------- -------
     <S>                                                  <C>            <C>
      1 day..............................................      31.0%      56.1%
      7 days.............................................      34.5       71.0
      1 month............................................      56.1       95.2
</TABLE>
 
 
                                       38
<PAGE>
 
Merger Consequences Analysis. CSFB analyzed the merger consequences based on
four scenarios and the following key assumptions:
 
  . pooling-of-interests accounting treatment for the merger;
 
  . full utilization of SEQUUS' NOL's to the extent SEQUUS generates earnings
    in future periods;
 
  . transaction expenses of $25 million expensed in 1998;
 
  . refinancing of SEQUUS' $5.0 million of debt while all of ALZA's debt
    remains outstanding;
 
  . use of the ALZA base case assumptions; and
 
  . consummation of the merger on December 31, 1998.
 
CSFB determined that without synergies and using the SEQUUS base case
assumptions, the exchange ratio of 0.40 of a share of ALZA common stock for
each share of SEQUUS common stock would result in a transaction that is
dilutive to ALZA's diluted 1999 and 2000 earnings, but accretive to 2001 and
2002 earnings.
 
CSFB determined that, assuming the conservative synergies case and using the
SEQUUS base case assumptions, the merger would be accretive to diluted earnings
per share for the years 1999 through 2002.
 
CSFB determined that, assuming the aggressive synergies case and using the
SEQUUS base case assumptions, the merger would be accretive to diluted earnings
per share for the years 1999 through 2002.
 
CSFB determined that, assuming the conservative synergies case and using the
SEQUUS downside case assumptions, the merger would be accretive to diluted
earnings per share for the years 1999 through 2002.
 
In an engagement letter dated August 26, 1998, between CSFB and SEQUUS, SEQUUS
agreed to pay CSFB, upon the consummation of the merger, a transaction fee
equal to 0.9% of the amount of total consideration paid up to $500 million plus
1.5% of the amount of total consideration paid in excess of $500 million. For
delivery of its fairness opinion on October 4, 1998, CSFB is entitled to
receive a fee of $400,000, which became payable upon delivery of its opinion,
regardless of the conclusions reached in its opinion, with such amount fully
credited against any transaction fee discussed above. The fees associated with
CSFB's engagement were determined through arm's-length negotiations between
SEQUUS and CSFB. In the past, CSFB has performed investment banking services
for SEQUUS. CSFB did not receive any significant compensation for such past
services.
 
In the ordinary course of its business, CSFB and its affiliates may actively
trade the debt and equity securities of both SEQUUS and ALZA for its and its
affiliates' own accounts and for the accounts of customers and, accordingly may
at any time hold a long or short position in such securities.
 
ALZA's Reasons for the Merger
 
ALZA's Board of Directors approved the merger on October 3, 1998. The ALZA
Board approved of the acquisition of SEQUUS, in part, due to its belief that
the merger will further ALZA's growth as a
 
                                       39
<PAGE>
 
research-based pharmaceutical company with leading drug delivery technologies
and its belief that the merger would constitute an additional step towards
ALZA's strategic goal of establishing a significant presence in the oncology
marketplace.
 
Regulatory Requirements
 
Under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 and the rules
promulgated thereunder by the Federal Trade Commission (the "FTC"), the merger
may not be consummated until notifications have been given and certain
information has been furnished to the FTC and the Antitrust Division of the
United States Department of Justice and specified waiting period requirements
have been satisfied. ALZA and SEQUUS each filed notification and report forms
under the Hart-Scott-Rodino Act with the FTC and the Antitrust Division on
October 15, 1998 and the required waiting period expired on November 19, 1998.
At any time before or after consummation of the merger, the Antitrust Division
or the FTC could take such action under the antitrust laws as it deems
necessary or desirable in the public interest, including seeking to enjoin the
consummation of the merger or seeking divestiture of substantial assets or
business of ALZA or SEQUUS. At any time before or after the consummation of the
merger, and regardless of whether that the Hart-Scott-Rodino Act waiting period
has been terminated, any state could take action under its antitrust laws as it
deems necessary or desirable in the public interest. That action could include
seeking to enjoin the consummation of the merger or seeking divestiture of
substantial assets or businesses of ALZA or SEQUUS. Private parties may also
seek to take legal action under antitrust laws.
 
Based on information available to them, ALZA and SEQUUS believe that the merger
can be effected in compliance with federal and state antitrust laws. However,
there can be no assurance that a challenge to the consummation of the merger on
antitrust grounds will not be made or that, if such a challenge were made, ALZA
and SEQUUS would prevail or would not be required to accept conditions,
possibly including certain divestitures, in order to consummate the merger.
 
Consummation of the merger is conditioned upon the receipt of all material
governmental authorizations, consents, orders and approvals, which if not
obtained would have a material adverse effect on SEQUUS or ALZA, subject to
waiver of such conditions, in accordance with the terms of the merger
agreement. Although ALZA and SEQUUS have agreed to use reasonable efforts to
secure all those approvals, there can be no assurance regarding the timing of
those approvals or that those approvals will, in fact, be obtained.
 
Interests of Certain Persons in the Merger
 
Certain members of SEQUUS' management and the SEQUUS Board may be deemed to
have interests in the merger that are in addition to their interests as
stockholders of SEQUUS generally. The SEQUUS Board was aware of these interests
and considered them, among other matters, in approving the merger agreement.
 
Indemnification and Insurance. The merger agreement provides that the
certificate of incorporation and bylaws of SEQUUS following the merger shall
contain, and provides that ALZA shall cause SEQUUS following the merger to
fulfill and honor, provisions with respect to indemnification and exculpation
that are substantially identical to those set forth in the certificate of
 
                                       40
<PAGE>
 
incorporation and bylaws of SEQUUS as of October 4, 1998; and further provides
that those provisions will not be repealed or otherwise modified for a period
of six years from the consummation of the merger in any manner that would
adversely affect the rights thereunder of any person who is or was a director
or officer of SEQUUS at any time before the consummation of the merger, or who
serves or has in the past served at the request of SEQUUS as a director,
officer, trustee, partner, fiduciary, employee or agent of another corporation,
partnership, joint venture, trust, pension or employee benefit plan or
enterprise at any time before the consummation of the merger. In addition, for
a period of six years from the consummation of the merger, ALZA has agreed to
indemnify and hold harmless those people indemnified by the certificate of
incorporation or bylaws of SEQUUS following the merger in connection with
claims, actions, suits and proceedings to the extent arising out of or
pertaining to the merger. ALZA has also agreed to cause SEQUUS following the
merger to maintain in effect for six years after the consummation of the merger
a policy of directors' and officers' liability insurance having terms
comparable to the terms of the policy in existence at the date of the merger
agreement.
 
Board of Directors Seat. ALZA has agreed to appoint Dr. I. Craig Henderson (if
willing and able to serve) to the ALZA Board as a member of Class III, to serve
until the election of Class III directors at the next annual meeting of ALZA's
stockholders.
 
Executive Severance Benefits Agreements. On September 25, 1998, the Special
Compensation Committee of the Board of Directors of SEQUUS authorized SEQUUS to
enter into Executive Severance Benefits Agreements with thirteen members of
SEQUUS management. The names and positions of the thirteen individuals and the
level of benefits approved for each individual are set forth below. The form of
Executive Severance Benefits Agreement approved by the Special Compensation
Committee provides that an executive will receive benefits if the executive's
employment is involuntarily terminated without "cause" or if the executive
voluntarily terminates his or her employment due to a "constructive
termination," in either case within thirteen (13) months following the
effective date of a change in control of SEQUUS (such as the merger). The
benefits provided under the Executive Severance Benefits Agreements include
salary continuation for a given period and payment of an additional amount
equal to one-twelfth ( 1/12) of the executive's highest bonus for the three
years prior to the change in control multiplied by the number of months for
which the executive's salary is continued. In addition, SEQUUS will continue to
pay the employer portion of the executive's group health insurance coverage for
the executive and his or her eligible dependents for the period during which
the executive's salary is continued, up to a maximum of eighteen (18) months.
The benefits provided under the Executive Severance Benefits Agreements range
in duration from a minimum of six (6) months to a maximum of twenty-four (24)
months. In order to receive benefits under an Executive Severance Benefits
Agreement, the executive must execute a release of all claims the executive may
have against SEQUUS and its successors and assigns.
 
                                       41
<PAGE>
 
<TABLE>
<CAPTION>
                                                                  DURATION OF
    NAME                                      POSITION         BENEFITS (MONTHS)
    ----                              ------------------------ -----------------
<S>                                   <C>                      <C>
I. Craig Henderson, M.D.............. Chief Executive Officer          24
Joseph Vallner, Ph.D................. Chief Operating Officer          24
Sally A. Davenport................... Corporate Secretary              24
Anthony H. Huang, Ph.D. ............. Vice President                   24
Francis J. Martin, Ph.D.............. Vice President                   24
John Richard......................... Executive Vice President         12
Michael Ramsay....................... Vice President                   12
Peter K. Working, Ph.D............... Vice President                   12
Edward Jacobs........................ Senior Vice President             6
Kenneth Cunningham, M.D.............. Vice President                    6
Aron Stein, Ph.D..................... Vice President                    6
Anthony Hendrickson.................. Corporate Controller              6
Gregory Ernst........................ Director                          6
</TABLE>
 
Accounting Treatment
 
The merger is intended to qualify as a pooling of interests for financial
reporting purposes in accordance with generally accepted accounting principles.
Consummation of the merger is conditioned upon receipt by ALZA and SEQUUS
within two days of the closing of the merger of letters from Ernst & Young LLP,
ALZA's and SEQUUS' independent auditors, reaffirming the firm's concurrence
with ALZA management's and SEQUUS management's conclusions as to the
appropriateness of pooling-of-interests accounting for the merger under APB No.
16, if consummated in accordance with the merger agreement.
 
Material Federal Income Tax Consequences
 
The following discussion summarizes the material federal income tax
considerations generally applicable to SEQUUS stockholders.
 
The discussion below is based on current law. Changes in the law could affect
the federal income tax consequences of the merger to SEQUUS stockholders.
 
This discussion assumes that SEQUUS stockholders hold their SEQUUS common stock
as capital assets within the meaning of Section 1221 of the Internal Revenue
Code. We have not and will not seek a ruling from the IRS in connection with
the merger. This discussion does not address the consequences of the merger
under state, local or foreign law, nor does the discussion address all aspects
of federal income taxation that may be important to a SEQUUS stockholder in
light of his or her particular circumstances or tax issues that may be
significant to SEQUUS stockholders subject to special rules, such as:
 
    . financial institutions,
 
    . insurance companies,
 
    . foreign individuals and entities,
 
    . tax-exempt entities,
 
    . dealers in securities,
 
 
                                       42
<PAGE>
 
    . persons who are subject to the alternative minimum tax provisions of
      the Internal Revenue Code,
 
    . persons who acquired SEQUUS common stock pursuant to the exercise of
      an employee option (or otherwise as compensation) or
 
    . persons who acquired SEQUUS common stock as part of an integrated
      investment (including a "straddle") composed of SEQUUS common stock
      and one or more other positions.
 
Accordingly, SEQUUS stockholders are urged to consult their own tax advisors as
to the specific tax consequences of the merger, including the applicable
federal, state, local and foreign tax consequences to them of the merger.
 
Heller Ehrman, counsel to ALZA, and Cooley Godward, counsel to SEQUUS, are of
the opinion that the merger will constitute a reorganization pursuant to
Section 368(a) of the Internal Revenue Code. In addition, it is a condition to
the obligation of each party to consummate the merger that it receive an
opinion of its counsel to the effect that the merger will constitute a
reorganization pursuant to Section 368(a) of the Code. These opinions neither
bind the IRS or the courts nor preclude the IRS or a court from adopting a
contrary position.
 
In addition, the tax opinions assume and are conditioned upon the following:
 
  .  the truth and accuracy of the statements, covenants, representations and
     warranties contained in the merger agreement, in the tax representations
     received from ALZA, Merger Sub and SEQUUS and in all other instruments
     and documents related to the formation and operation of ALZA, Merger Sub
     and SEQUUS examined by and relied upon by Heller Ehrman and Cooley
     Godward in connection with their opinions;
 
  .  that original documents submitted to counsel are authentic, documents
     submitted to counsel as copies conform to the original documents, and
     that those documents have been (or will be by the Effective Time) duly
     and validly executed and delivered;
 
  .  that all covenants contained in the merger agreement and the tax
     representations received from ALZA, Merger Sub and SEQUUS are performed
     without waiver or breach of any material provision; and
 
  .  that any representation or statement made "to the best of knowledge" or
     similarly qualified is correct without being qualified.
 
As a reorganization, the merger will have the following federal income tax
consequences (subject to the limitations and qualifications referred to in this
proxy statement/prospectus):
 
Exchange of SEQUUS Common Stock for ALZA Common Stock. Except as discussed
below, no gain or loss will be recognized for federal income tax purposes by
SEQUUS stockholders who exchange their SEQUUS common stock for ALZA common
stock pursuant to the merger. Each SEQUUS stockholder's aggregate tax basis in
the ALZA common stock he or she receives in the merger will be the same as his
or her aggregate tax basis in the SEQUUS common stock surrendered in the merger
(reduced by any tax basis allocable to fractional shares exchanged for cash),
and the holding period of the ALZA common stock received will include the
holding period of the SEQUUS common stock surrendered.
 
 
                                       43
<PAGE>
 
Cash Received Instead of Fractional Shares. The payment of cash to a SEQUUS
stockholder instead of a fractional share in ALZA common stock generally should
result in the recognition of capital gain or loss measured by the difference
between the amount of cash received and the portion of the tax basis of the
SEQUUS common stock allocable to that fractional share interest. In the case of
an individual, capital gain is generally subject to United States federal
income tax at a maximum rate of 20% if such individual has held his or her
SEQUUS common stock for more than one year at the time of the merger, and at
ordinary income rates (as a short-term capital gain) if the individual has held
his or her SEQUUS common stock for one year or less at the time of the
consummation of the merger. The deductibility of capital losses may be limited.
 
Reporting Requirements. Each SEQUUS stockholder that receives ALZA common stock
in the merger will be required to file a statement with his or her federal
income tax return setting forth his or her basis in the SEQUUS common stock
surrendered and the fair market value of the ALZA common stock and cash
received in the merger, and to retain permanent records of these facts relating
to the merger.
 
Backup Withholding. Unless an exemption applies under applicable law and
regulations, the exchange agent is required to withhold, and will withhold, 31%
of any cash payments to a SEQUUS stockholder in the merger unless the
stockholder provides the appropriate form as described below. Each SEQUUS
stockholder should complete and sign the Substitute Form W-9 included as part
of the letter of transmittal to be sent to each SEQUUS stockholder, so as to
provide the information, including such stockholder's taxpayer identification
number, and certification necessary to avoid backup withholding, unless an
applicable exemption exists and is proved in a manner satisfactory to ALZA and
the exchange agent.
 
The preceding discussion is not meant to be a complete analysis or discussion
of all potential tax effects relevant to the merger. Thus, SEQUUS stockholders
are urged to consult their own tax advisors as to the specific tax consequences
to them of the merger, including tax return reporting requirements, federal,
state, local and other applicable tax laws and the effect of any proposed
changes in the tax laws.
 
Absence of Appraisal Rights
 
SEQUUS is incorporated under Delaware law, and the Delaware General Corporation
Law governs the availability of appraisal rights with respect to mergers
involving SEQUUS. SEQUUS stockholders are not entitled to appraisal rights
under the Delaware General Corporation Law in connection with the merger.
 
 
                                       44
<PAGE>
 
                The Merger Agreement and the Related Agreements
 
This proxy statement/prospectus contains a brief summary of certain provisions
of the merger agreement and other agreements entered into in connection with
the merger agreement. The summary of the merger agreement is qualified in its
entirety by reference to the full text of the merger agreement, which is
included as Annex A hereto and which is incorporated herein by reference.
 
Effective Time; Effect of Merger
 
The merger will become effective upon the filing of a Certificate of Merger
with the Secretary of State of the State of Delaware or at such later time as
may be agreed to in writing by ALZA, SEQUUS and Merger Sub and as specified in
the Certificate of Merger (the "Effective Time"). The closing of the merger
(the "Closing") will occur at the offices of Heller Ehrman on a date to be
specified by the parties, which will be no later than the first business day
after the satisfaction or waiver of the conditions to the merger or any other
date as the parties agree (the "Closing Date"). The Certificate of Merger will
be filed on the Closing Date. The Closing and the Effective Time are
anticipated to be on or about March 16, 1999.
 
At the Effective Time (a) Merger Sub shall be merged with and into SEQUUS, (b)
the separate corporate existence of Merger Sub shall cease, and (c) SEQUUS
shall be the surviving corporation. SEQUUS, as the surviving corporation after
the merger, is sometimes referred to in this proxy statement/prospectus as the
"Surviving Corporation".
 
Conversion of Shares
 
At the Effective Time, by virtue of the merger and without any action on the
part of Merger Sub, SEQUUS or the holders of SEQUUS securities, each
outstanding share of SEQUUS common stock, together with the associated rights
under SEQUUS' Rights Agreement dated as of April 17, 1997, between SEQUUS and
ChaseMellon Shareholder Services, L.L.C., will be canceled and converted into
0.40 of a share of ALZA common stock.
 
The exchange ratio of 0.40 will be adjusted for, or ALZA will make appropriate
provisions to reflect the effect of, any stock split, reverse split, stock
dividend, extraordinary dividend or distribution, reorganization,
recapitalization or other like change with respect to ALZA common stock or
SEQUUS common stock occurring or having a record or effective date after the
date of the merger agreement. The exchange ratio will not be adjusted under any
other circumstances.
 
Each share of common stock of Merger Sub outstanding immediately prior to the
Effective Time will be converted into and exchanged for one share of SEQUUS
common stock as the Surviving Corporation.
 
No fractional shares will be issued by virtue of the merger. In lieu of a
fraction of a share of ALZA common stock, each SEQUUS stockholder will receive
(after all fractional shares to be received by such holder are aggregated) from
ALZA an amount of cash (rounded down to the nearest whole cent) equal to the
product of (a) such fraction, multiplied by (b) the closing price of a share of
ALZA common stock on the last trading day immediately preceding the Effective
Time, as reported on the NYSE.
 
 
                                       45
<PAGE>
 
Promptly after the Effective Time, ALZA, acting through an exchange agent, will
deliver to each SEQUUS stockholder of record as of the Effective Time a letter
of transmittal with instructions to be used by that stockholder in surrendering
certificates which, prior to the merger, represented shares of SEQUUS common
stock. Certificates should not be surrendered by the holders of SEQUUS common
stock until the holders receive the letter of transmittal from the Exchange
Agent. At the Effective Time, each then outstanding option or right to purchase
SEQUUS common stock will be assumed by ALZA without any action on the part of
the holder of the option. Option and stock purchase agreements need not be
surrendered.
 
Treatment of Options and Warrants
 
As of February 10, 1999 there were options to purchase a total of 4,022,587
shares of SEQUUS common stock outstanding.
 
At the Effective Time, ALZA shall, to the fullest extent permitted by
applicable law, assume all options to purchase SEQUUS common stock then
outstanding under SEQUUS' 1987 Employee Stock Option Plan, 1987 Consultant
Stock Option Plan, 1990 Director Stock Option Plan, and Equity Incentive Plan
(in each case, as amended prior to the date of the merger agreement) (the
"SEQUUS Stock Option Plans") and purchase rights under the SEQUUS Employee
Stock Purchase Plan (the "SEQUUS Purchase Plan") as described below under "--
Employee Benefits." Each SEQUUS Stock Option, whether or not exercisable at the
Effective Time, to the full extent permitted by applicable law, shall be
assumed by ALZA in a manner so that it shall be exercisable after the Effective
Time upon the same terms and conditions as under the SEQUUS Stock Option Plan
pursuant to which it was granted and the applicable option agreement issued
thereunder. See the more detailed discussion under "Employee Benefits" below.
 
As of the Effective Time, ALZA shall assume, in accordance with their terms,
all of the warrants to purchase SEQUUS common stock dated May 19, 1995
outstanding as of the Effective Time (the "1995 Warrants"), so that they shall
each be exercisable on the terms and conditions provided in such 1995 Warrants,
with adjustments based on the exchange ratio.
 
Stock Ownership Following the Merger
 
Based on the capitalization of SEQUUS as of the close of business on February
10, 1999 and the exchange ratio, an aggregate of approximately 13,123,066
shares of ALZA common stock will be issued to SEQUUS stockholders in the
merger. At the Effective Time, ALZA will assume all options outstanding
immediately prior to the Effective Time under the SEQUUS Stock Option Plans
(the "SEQUUS Stock Options"), all purchase rights outstanding under the SEQUUS
Stock Purchase Plan and all 1995 Warrants exercisable for an aggregate of up to
approximately 1,691,338 additional shares of ALZA common stock. Based on the
number of shares of ALZA common stock issued and outstanding as of February 10,
1999, and after giving effect to the issuance of ALZA common stock in the
merger, the former holders of SEQUUS common stock would hold, and have voting
power with respect to approximately 9.7% of ALZA's total issued and outstanding
shares immediately after the Effective Time. Holders of former SEQUUS options,
purchase rights and warrants would hold options and rights to acquire
approximately 1.25% of the total issued and outstanding shares of ALZA common
stock immediately after the Effective Time (assuming the exercise of only such
options and rights).
 
                                       46
<PAGE>
 
Representations and Warranties
 
SEQUUS, ALZA, and Merger Sub have made representations in the merger agreement
relating to, among other things:
 
  .  their respective capitalization and organization and similar corporate
     matters;
 
  .  authorization, execution, delivery and enforceability of the merger
     agreement;
 
  .  conflicts under governing documents, required consents or approvals, and
     violations of any agreements or law;
 
  .  documents filed with the SEC and the accuracy of information contained
     therein;
 
  .  absence of material adverse events, changes or effects;
 
  .  tax matters relating to the proposed merger;
 
  .  the absence of undisclosed liabilities;
 
  .  compliance with laws, including food and drug laws;
 
  .  litigation;
 
  .  intellectual property matters; and
 
  .  the disclosure and enforceability of certain material contracts.
 
SEQUUS has made additional representations, among others, relating to:
 
  .  compliance with environmental and tax laws and regulations;
 
  .  retirement and other employee plans and matters;
 
  .  certain business matters relating to permits and licenses and insurance;
 
  .  liabilities relating to employees, labor unions or other organizations;
 
  .  finders and brokers;
 
  .  title to property; and
 
  .  year 2000 compliance.
 
None of the representations and warranties of SEQUUS, ALZA or Merger Sub in the
merger agreement described above will survive the Effective Time.
 
In addition, ALZA and SEQUUS have agreed to make representations that will
serve as the basis for the tax opinions of Heller Ehrman and Cooley Godward
described under "The Merger--Certain Federal Income Tax Consequences."
 
Conduct of ALZA's Business and SEQUUS' Business Prior to the Merger
 
Until the earlier of the termination of the merger agreement or the Effective
Time, SEQUUS has agreed to:
 
  .  conduct its operations in all material respects according to its
     ordinary and usual course of business consistent with past practice,
 
                                       47
<PAGE>
 
  .  use all commercially reasonable efforts to preserve intact its business
     organization, to keep available the services of its officers and
     employees in each business function and to maintain satisfactory
     relationships with suppliers, distributors, customers and others having
     business relationships with it, and
 
  .  not take any action which could reasonably be expected to adversely
     affect its ability to consummate the merger or the other transactions
     contemplated by the merger agreement.
 
The merger agreement further provides that, during the period from the date of
the merger agreement until the Effective Time, SEQUUS and its subsidiaries will
not, subject to certain exceptions, take any of the following actions:
 
  .  enter into, violate or amend any of the material terms of certain
     material agreements except in the ordinary course of business and
     consistent with past practice;
 
  .  split, combine or reclassify any shares of its capital stock;
 
  .  authorize or enter into any agreement with respect to
 
    -- any plan of liquidation or dissolution,
 
    -- any acquisition or disposition of a material amount of assets or
       securities, except purchases or sales of inventory and equipment in
       the ordinary course of business consistent with past practice, or
 
    -- any material change in capitalization;
 
  .  fail to renew any insurance policy naming it as a beneficiary or a loss
     payee or allow any policy to be canceled, terminated or materially and
     adversely altered;
 
  .  maintain its books and records in a manner other than in the ordinary
     course of business and consistent with past practice;
 
  .  enter into any hedging, option, derivative or other similar transaction
     or any foreign exchange position or contract for the exchange of
     currency other than in the ordinary course of business and consistent
     with past practice;
 
  .  institute any change in its accounting methods;
 
  .  make any change or material election with respect to taxes;
 
  .  take any action, or fail to take any action, which could reasonably be
     expected to prevent ALZA from accounting for the merger as a pooling of
     interests;
 
  .  suspend, terminate or otherwise discontinue any planned or ongoing
     material research and development activities;
 
  .  make any material amendment to any New Drug Application, or its foreign
     equivalents; or
 
  .  take, or agree to take, any action which would make certain of its
     representations or warranties contained in the merger agreement untrue
     or incorrect or any action which would reasonably be expected to result
     in certain conditions to the merger not being satisfied.
 
In addition, until the Effective Time, ALZA will not do or permit any of its
subsidiaries to:
 
  .  take any action which could reasonably be expected to adversely affect
     ALZA's ability to consummate the merger,
 
  .  take any action which could reasonably be expected to prevent ALZA from
     accounting for the merger as a pooling of interests,
 
                                       48
<PAGE>
 
  .  take, or agree to take, any action which could reasonably be expected to
     result in certain conditions to the merger not being satisfied, and
 
  .  consummate, or agree to consummate:
 
    -- any transaction or series of related transactions to acquire shares
       representing a controlling interest in any corporation or other
       entity pursuant to a tender offer, exchange offer, merger,
       consolidation, share exchange, acquisition of stock or other
       business combination or acquisition in which the aggregate
       consideration paid or payable by ALZA and its subsidiaries is or
       would be in excess of $750 million; or
 
    -- any other transaction or series of related transactions to acquire
       or license assets in which the aggregate consideration paid or
       payable by ALZA and its subsidiaries is or would be in excess of
       $750 million, in each case, determined as of the date of the
       definitive agreement relating to such transaction.
 
Conduct of Business Following the Merger
 
Pursuant to the merger, Merger Sub will cease to exist as a corporation and
will be merged with and into SEQUUS, with SEQUUS as the Surviving Corporation.
All property, rights, privileges, powers and franchises of SEQUUS and Merger
Sub will vest in the Surviving Corporation; all debts, liabilities and duties
of SEQUUS and Merger Sub will become the debts, liabilities and duties of the
Surviving Corporation; and the Surviving Corporation will be a wholly owned
subsidiary of ALZA.
 
Pursuant to the merger agreement, the certificate of incorporation of Merger
Sub in effect immediately prior to the Effective Time will become the
certificate of incorporation of the Surviving Corporation, except that the name
of the Surviving Corporation shall be "SEQUUS Pharmaceuticals, Inc." and the
bylaws of Merger Sub will become the bylaws of the Surviving Corporation. The
directors of Merger Sub at the Effective Time will become the initial directors
of the Surviving Corporation. The officers of Merger Sub immediately prior to
the Effective Time will become the initial officers of the Surviving
Corporation.
 
Pursuant to the merger agreement, Dr. I. Craig Henderson will be appointed to
the ALZA Board.
 
No Solicitation
 
SEQUUS has agreed that it shall not, and shall cause its subsidiaries not to,
and shall use its best efforts to cause its and its subsidiaries' respective
officers and directors not to, and shall use commercially reasonable efforts to
cause its non-officer employees, investment bankers, attorneys or other agents
retained by or acting on behalf of SEQUUS or any of its subsidiaries not to:
 
  .   initiate, solicit or knowingly encourage, directly or indirectly, any
     inquiries or the making of any proposal that constitutes or is
     reasonably likely to lead to any Acquisition Proposal (as defined
     below),
 
  .   engage in negotiations or discussions with, or furnish any non-public
     information or data to, any third party relating to an Acquisition
     Proposal, or
 
  .   enter into any agreement with a potential acquiror (other than a
     confidentiality, standstill and nonsolicitation agreement which
     satisfies the requirements set forth below) with respect to any
     Acquisition Proposal or approve any Acquisition Proposal.
 
                                       49
<PAGE>
 
For the purposes of the merger agreement, an "Acquisition Proposal" means any
bona fide proposal (which may be subject to a "due diligence" condition),
whether in writing or otherwise, made by a third party for:
 
  .   a transaction or series of related transactions pursuant to which the
     third party acquires or would acquire shares (or securities exercisable
     for or convertible into shares) representing more than twenty percent
     (20%) of the outstanding shares of SEQUUS common stock, pursuant to a
     tender offer or exchange offer or otherwise;
 
  .  a merger, consolidation, share exchange or other business combination
     involving SEQUUS or any of its subsidiaries if, upon consummation of
     that merger, consolidation, share exchange or other business
     combination, the third party (or its shareholders) owns or would own
     more than twenty percent (20%) of the outstanding equity securities of
     SEQUUS;
 
  .  any other transaction or series of related transactions pursuant to
     which the third party acquires or would acquire primary control of
     assets of SEQUUS or any of its subsidiaries (including certain
     intellectual property of SEQUUS) if the aggregate dollar value of the
     consideration proposed to be paid by the third party to SEQUUS in that
     transaction exceeds $100 million; or
 
  .  any transaction or series of related transactions pursuant to which the
     third party acquires or would acquire control of the SEQUUS Board or by
     which nominees of the third party are (or would be) elected or appointed
     to a majority of the seats on the SEQUUS Board.
 
SEQUUS and the SEQUUS Board may take the following actions:
 
  .  may participate in discussions or negotiations with or furnish non-
     public information or data to any third party that has made an
     unsolicited Acquisition Proposal; and
 
  .   may approve or accept an unsolicited Acquisition Proposal if the SEQUUS
     Board
 
    (a) determines in good faith, after receiving written advice from its
        financial advisor, that that Acquisition Proposal is a Superior
        Proposal (as defined below), and
 
    (b)  determines in good faith, following consultation with outside
         legal counsel, that the failure to participate in those
         discussions or negotiations or to furnish such information or
         approve or accept that Acquisition Proposal would violate the
         SEQUUS Board's fiduciary duties under applicable law.
 
For purposes of the merger agreement, the term "Superior Proposal" means any
Acquisition Proposal, made in writing and not initiated, solicited or
encouraged in violation of the merger agreement, on terms which the SEQUUS
Board determines in good faith to be more favorable to SEQUUS and its
stockholders or to its stockholders than the merger (after receiving the
written advice of SEQUUS' financial advisor that the value of the consideration
provided for in that proposal is superior to the value of the consideration
provided for in the merger), for which financing, to the extent required, is
then committed or which, in the good faith judgment of the SEQUUS Board, after
receiving written advice from its financial advisor, is reasonably capable of
being financed by the potential acquiror.
 
In addition, SEQUUS has agreed to promptly, and in any event within 24 hours,
inform ALZA in writing in the event that SEQUUS shall provide information
relating to an Acquisition Proposal or
 
                                       50
<PAGE>
 
receive any Acquisition Proposal (or any material amendment to an Acquisition
Proposal previously received), and shall furnish to ALZA the identity of the
recipient of that information to be provided and/or the potential acquiror and
the terms of such Acquisition Proposal (or material amendment).
 
Under the merger agreement, the SEQUUS Board is required to recommend the
approval and adoption of the merger agreement and approval of the merger to its
stockholders and the SEQUUS Board may not:
 
  .  withdraw or modify or propose to withdraw or modify, in any manner
     adverse to ALZA, its approval and recommendation of the merger agreement
     and the merger or
 
  .  approve or recommend, or propose to approve or recommend, any
     Acquisition Proposal
 
unless, in each case, the SEQUUS Board has
 
  .  determined that the Acquisition Proposal is a Superior Proposal,
 
  .  determined in good faith, following consultation with outside legal
     counsel, that the failure to take that action would violate the SEQUUS
     Board's fiduciary duties under applicable law and
 
  .  given at least 72 hours prior written notice to ALZA of that
     determination.
 
Fees, Expenses and Termination Fees
 
Except as set forth below, all fees and expenses incurred in connection with
the merger agreement and the transactions contemplated thereby will be paid by
the party that incurs them. ALZA and SEQUUS will share equally the filing fees
paid in connection with the filing of this proxy statement/prospectus and the
Registration Statement of which this proxy statement/prospectus is a part, and
the costs of printing and mailing this proxy statement/prospectus.
 
Subject to certain exceptions specified in the merger agreement, SEQUUS has
agreed to pay ALZA a termination fee of $25 million if:
 
  .  there shall not have occurred any material adverse effect to ALZA and
     its subsidiaries taken as a whole and the merger agreement is terminated
     by ALZA because:
 
    -- the SEQUUS Board fails to recommend the approval of the merger
       agreement to SEQUUS stockholders, or withdraws, amends or modifies
       in a manner adverse to ALZA its recommendation to SEQUUS
       stockholders for approval of the merger agreement;
 
    -- a tender offer for at least 20% of the outstanding shares of capital
       stock of SEQUUS is commenced prior to the special meeting, and
       within the time required by Rule 14e-2(a) under the Exchange Act,
       the SEQUUS Board fails to recommend against acceptance of the tender
       offer, or takes no position with respect to the tender offer, or
       states its inability to take a position with respect to the tender
       offer;
 
    -- an Acquisition Proposal is publicly announced and SEQUUS or the
       SEQUUS Board takes any position (including stating an inability to
       make a recommendation) with respect to any Acquisition Proposal
       within 10 days after the public announcement of the Acquisition
       Proposal other than a recommendation to reject the Acquisition
       Proposal;
 
    -- the SEQUUS Board accepts or recommends to the stockholders of SEQUUS
       a Superior Proposal; or
 
 
                                       51
<PAGE>
 
    -- the SEQUUS Board resolves to take any of the actions listed above;
 
  .  there shall not have occurred any material adverse effect to ALZA and
     its subsidiaries taken as a whole and the merger agreement is terminated
     by SEQUUS because SEQUUS has accepted or recommended to its stockholders
     a Superior Proposal; or
 
  .  there shall not have occurred any material adverse effect to ALZA and
     its subsidiaries taken as a whole and one of the following took place:
 
    -- the merger agreement is terminated by either ALZA or SEQUUS because
       the SEQUUS stockholders do not approve the merger and ALZA shall not
       have breached in any material respect any of its obligations under
       the merger agreement in any manner that shall have proximately
       contributed to the failure of the SEQUUS stockholders to approve the
       merger;
 
    -- prior to the time of the special meeting, an Acquisition Proposal
       has been publicly announced and not withdrawn;
 
    -- prior to such termination, SEQUUS has not accepted or approved a
       Superior Proposal; and
 
    -- within one year of such termination, SEQUUS consummates a
       transaction that would constitute an Acquisition Proposal of the
       type described in the first three bullet points on page 49.
 
Conditions to the Merger
 
The respective obligations of SEQUUS, ALZA and Merger Sub to effect the merger
are subject to the satisfaction or waiver in writing at or prior to the
Effective Time of the following conditions:
 
  .  SEQUUS stockholders shall have duly approved and adopted the merger
     agreement and the merger;
 
  .  the SEC shall have declared effective the Registration Statement of
     which this proxy statement/prospectus is a part, and the Registration
     Statement shall not be subject to any stop order suspending that
     effectiveness or proceedings seeking a stop order;
 
  .  the ALZA common stock issuable in connection with the merger shall have
     been approved for listing subject to official notice of issuance on the
     NYSE;
 
  .  the waiting period applicable to consummation of the merger under the
     HSR Act shall have expired or been terminated, and all similar
     governmental requirements the failure with which to comply would be
     reasonably likely to have a material adverse effect on ALZA or SEQUUS
     shall have been met;
 
  .  ALZA and SEQUUS, respectively, shall have received opinions of Heller
     Ehrman and Cooley Godward to the effect that the merger will constitute
     a reorganization within the meaning of Section 368(a) of the Code;
 
  .  no writ, order, temporary restraining order, preliminary injunction or
     injunction shall have been enacted, entered, promulgated or enforced by
     any court or other tribunal or governmental body or authority, which
     remains in effect, and prohibits the consummation of the merger or
     otherwise makes it illegal, nor shall any governmental agency have
     instituted any action, suit or proceeding which remains pending and
     which seeks, and which is reasonably likely, to enjoin, restrain or
     prohibit the consummation of the merger in accordance with the terms of
     the merger agreement; and
 
 
                                       52
<PAGE>
 
  .  each of ALZA and SEQUUS shall have received a letter from its
     independent accountants, dated as of the Effective Time, in form and
     substance reasonably satisfactory to it, affirming the firm's
     concurrence with ALZA management's conclusion and SEQUUS management's
     conclusion that the merger qualifies for pooling-of-interests accounting
     under APB Opinion No. 16, if consummated in accordance with the merger
     agreement.
 
In addition, the obligations of SEQUUS to consummate and effect the merger are
subject to the satisfaction or waiver in writing at or prior to the Effective
Time, of each of the following conditions, any of which may be waived in
writing by SEQUUS:
 
  .  the representations and warranties of ALZA and Merger Sub contained in
     the merger agreement shall be true and correct in all material respects,
     as of the Closing Date, with the same force and effect as if made at the
     Closing Date, except
 
    -- for changes specifically permitted by the terms of the merger
       agreement,
 
    -- that the accuracy of the representations and warranties that by
       their terms speak as of the date of the merger agreement or some
       other date will be determined as of that date, and
 
    -- where the failure of those representations and warranties to be so
       true and correct does not have a material adverse effect on ALZA;
 
  .  ALZA and Merger Sub shall have performed and complied in all material
     respects with all agreements and obligations required by the merger
     agreement to be performed or complied with by them on or prior to the
     Closing Date; and
 
  .  there shall not have occurred any change, event or effect with respect
     to ALZA or its subsidiaries having a material adverse effect (as defined
     in the merger agreement) on ALZA and its subsidiaries taken together.
 
In addition, the obligations of ALZA and Merger Sub to consummate and effect
the merger are subject to the satisfaction or waiver in writing at or prior to
the Effective Time, of each of the following conditions, any of which may be
waived in writing by ALZA:
 
  .  the representations and warranties of SEQUUS contained in the merger
     agreement shall be true and correct in all material respects, as of the
     Closing Date, with the same force and effect as if made at the Closing
     Date, except
 
    -- for changes specifically permitted by the terms of the merger
       agreement,
 
    -- that the accuracy of the representations and warranties that by
       their terms speak as of the date of the merger agreement or some
       other date will be determined as of that date, and
 
    -- where the failure of those representations and warranties to be so
       true and correct does not have a material adverse effect on SEQUUS;
 
  .  SEQUUS shall have performed or complied in all material respects with
     all agreements and obligations required by the merger agreement to be
     performed or complied with by it on or prior to the Closing Date; and
 
  .  there shall not have occurred any change, event or effect with respect
     to SEQUUS or its subsidiaries taken together having a material adverse
     effect (as defined in the merger agreement) on SEQUUS.
 
                                       53
<PAGE>
 
Currently, both ALZA and SEQUUS anticipate that they will satisfy all
conditions to the merger at or prior to consummation of the merger.
 
Termination of the Merger Agreement
 
The merger agreement provides that it may be terminated at any time prior to
the Effective Time, whether before or after approval of the merger by the
SEQUUS stockholders:
 
  .  by mutual written consent of the parties duly authorized by the ALZA
     Board, the board of directors of Merger Sub and the SEQUUS Board;
 
  .  by either ALZA or SEQUUS if the merger shall not have been consummated
     on or before April 1, 1999 (provided, however, that such right to
     terminate will not be available to any party that breached in any
     material respect its obligations under the merger agreement in a manner
     that proximately contributed to the failure to consummate the merger by
     such date);
 
  .  by either ALZA or SEQUUS if:
 
    -- a statute, rule, regulation or executive order shall have been
       enacted, entered or promulgated prohibiting the consummation of the
       merger substantially on the terms contemplated by the merger
       agreement; or
 
    -- a court of competent jurisdiction or other governmental entity shall
       have issued a final and non-appealable order, decree, ruling or
       injunction, or taken any other final and non-appealable action, that
       permanently restrains, enjoins or otherwise prohibits the merger
       substantially on the terms contemplated by the merger agreement
       (provided that the party exercising the right to terminate has used
       its reasonable best efforts to remove that order, decree, ruling or
       injunction);
 
  .  by either SEQUUS or ALZA if the SEQUUS stockholders have not approved
     the merger agreement at the special meeting (provided that the right to
     terminate will not be available to any party that breached in any
     material respect its obligations under the merger agreement in a manner
     that proximately contributed to the failure to obtain that stockholder
     approval);
 
  .  by ALZA if the SEQUUS Board withdraws or modifies in a manner adverse to
     ALZA (or publicly announces its intention to withdraw or modify) its
     recommendation of the merger agreement, or fails within the ten-day time
     period prescribed by Rule 14e-2 under the Exchange Act to recommend
     against acceptance of a competing tender offer for at least 20% of the
     outstanding shares of SEQUUS capital stock (including by taking no
     position with respect to acceptance of that tender offer or stating its
     inability to take a position);
 
  .  an Acquisition Proposal is publicly announced and SEQUUS or the SEQUUS
     Board takes any position (including stating an inability to make a
     recommendation) with respect to that Acquisition Proposal other than a
     recommendation to reject that Acquisition Proposal;
 
  .  by SEQUUS if the SEQUUS Board accepts or recommends to SEQUUS
     stockholders a Superior Proposal in accordance with the merger
     agreement; or
 
  .  by ALZA or SEQUUS if the other party has materially breached any of its
     representations, warranties, covenants or agreements in the merger
     agreement and that breach has not been cured within 30 days after notice
     of the breach has been received by the party allegedly in breach
     provided that neither party may terminate the agreement if it shall have
     breached in any material respect its obligations under the merger
     agreement in any manner that proximately caused the breach by the other
     party.
 
                                       54
<PAGE>
 
Employee Benefits
 
At the Effective Time, ALZA will assume each outstanding option to purchase
shares of SEQUUS common stock under the SEQUUS Stock Option Plans, whether that
option is vested or unvested. Each SEQUUS Stock Option assumed by ALZA will
continue to have and be subject to substantially the same terms and conditions
as applied under the SEQUUS Stock Option Plans and related documents, except
that:
 
  .  each such SEQUUS Stock Option will be exercisable for that number of
     whole shares of ALZA common stock equal to the product of the number of
     shares of SEQUUS common stock that were issuable on exercise of such
     option immediately prior to the Effective Time, multiplied by the
     exchange ratio, and rounded down to the nearest whole number of shares
     of ALZA common stock, and
 
  .  the per share exercise price for the shares of ALZA common stock
     issuable on exercise of the SEQUUS Stock Option will equal the quotient
     determined by dividing the exercise price per share of SEQUUS common
     stock at which that option was exercisable immediately prior to the
     Effective Time by the exchange ratio, rounded up to the nearest whole
     cent.
 
The repurchase rights associated with certain SEQUUS Stock Options will lapse
at the Effective Time by reason of the resolutions of the SEQUUS Board approved
on March 10, 1994 and June 19, 1995. The parties intend that the SEQUUS
incentive stock options assumed by ALZA will continue to qualify as incentive
stock options under Section 422 of the Code, to the extent those options
qualified as such immediately prior to the Effective Time.
 
SEQUUS will amend the SEQUUS Purchase Plan so that as of the Effective Time:
 
  .  the SEQUUS Purchase Plan shall provide that no additional purchase
     rights shall be issued under it;
 
  .  the purchase dates of each then-outstanding purchase right granted under
     the SEQUUS Purchase Plan shall conform to the purchase dates then in
     effect under the ALZA Amended and Restated Employee Stock Purchase Plan
     (the "ALZA Purchase Plan");
 
  .  each purchase right granted under the SEQUUS Purchase Plan shall
     terminate (if it has not previously terminated by its terms) on the
     purchase date under the ALZA Purchase Plan immediately preceding August
     1, 1999, or if earlier, on the date that the holder of that purchase
     right enrolls in the ALZA Purchase Plan; and
 
  .  each purchase right shall thereafter be exercisable for whole shares of
     ALZA common stock (rounded down to the nearest whole share) equal to the
     number of shares of SEQUUS common stock for which that purchase right
     would otherwise have been exercisable, determined as of the relevant
     grant date under the SEQUUS Purchase Plan, multiplied by the exchange
     ratio at a purchase price per share equal to 85% of the lower of the
     quotient determined by dividing the fair market value of a share of
     SEQUUS common stock on the relevent grant date under the SEQUUS Purchase
     Plan by the Exchange Ratio, rounded up to the nearest whole cent, or the
     fair market value of a share of ALZA common stock on the relevant
     purchase date. As of the Effective Time, each then-outstanding purchase
     right granted under the SEQUUS Purchase Plan shall be assumed by ALZA in
     such a manner that it shall be exercisable upon the same terms and
     conditions (as amended as described above) as under the SEQUUS Purchase
     Plan immediately before the Effective Time.
 
                                       55
<PAGE>
 
No later than ten (10) business days after the Closing Date, ALZA will file a
Registration Statement on Form S-8 under the Securities Act of 1933 covering
the shares of ALZA common stock issuable pursuant to outstanding options and
rights to purchase SEQUUS common stock assumed by ALZA pursuant to the merger.
 
In general, employees of SEQUUS who become employees of the Surviving
Corporation or ALZA at the Effective Time will be credited with years of
service at SEQUUS for purposes of determining eligibility, vesting and benefit
accrual under benefit plans of ALZA, subject to certain exceptions, including,
with respect to retirement benefits under plans maintained by ALZA, such years
of service will be credited for purposes of determining eligibility and vesting
but not for purposes of benefit accrual.
 
Absence of Appraisal Rights
 
Section 262 of the DGCL provides appraisal rights to stockholders of Delaware
corporations in certain situations. Section 262 appraisal rights are not
available, however, to stockholders of a corporation, such as SEQUUS, whose
securities are listed on a national securities exchange or designated as
national market system securities on an interdealer quotation system by the
National Association of Securities Dealers, Inc., and whose stockholders are
not required to accept in exchange for their stock anything other than stock of
another corporation listed on a national securities exchange or on an
interdealer quotation system by the NASD, and cash in lieu of fractional
shares. Since the SEQUUS common stock is traded on Nasdaq, and because the
SEQUUS stockholders are being offered ALZA common stock, which is traded on the
NYSE, and cash in lieu of fractional shares, SEQUUS stockholders will not have
appraisal rights with respect to the merger. The DGCL does not provide
appraisal rights to stockholders of a corporation, such as ALZA, that issues
shares in connection with a merger but is not itself a constituent corporation
in the merger.
 
Affiliate Agreements
 
The following is a brief summary of material terms of the Affiliate Agreements,
copies of forms of which are attached as Annex B-1 and Annex B-2 to this proxy
statement/prospectus and incorporated herein by this reference. This summary is
qualified in its entirety by reference to the Affiliate Agreements. SEQUUS
stockholders are urged to read the Affiliate Agreements in their entirety for a
more complete description of the rights and obligations of the parties under
these agreements.
 
"Affiliates" (within the meaning of Rule 145 under the Securities Act) of
SEQUUS have entered into agreements that:
 
 . prohibit the sale, transfer or other disposition of ALZA common stock
   received by that person in the merger unless
 
  --the transaction is permitted under Rule 145 under the Securities Act,
 
  --counsel reasonably satisfactory to ALZA shall have advised ALZA in a
    written opinion letter satisfactory to ALZA and ALZA's legal counsel and
    on which ALZA and its legal counsel may rely that no registration under
    the Securities Act would be required in connection with the proposed
    sale, transfer or other disposition,
 
  --the sale, transfer or other disposition is effected pursuant to an
    effective registration statement under the Securities Act, or
 
                                       56
<PAGE>
 
  -- an authorized representative of the Commission shall have rendered
    written advice to that person (with a copy delivered to ALZA) to the
    effect that the Commission would take no action, or that the Commission
    staff would not recommend that the Commission take action, with respect
    to the proposed disposition; and
 
 . prohibit the sale, transfer, exchange, pledge or other distribution
 
  -- within the 30 days prior to the consummation of the merger, of any
    shares of the common stock of SEQUUS held by the Affiliate, except
    pursuant to and upon consummation of the merger, or
 
  -- until such time as results covering at least 30 days' combined
    operations of SEQUUS and ALZA are publicly announced by ALZA, of any
    shares of ALZA common stock received by the Affiliate in the merger.
 
"Affiliates" of ALZA have entered into agreements that prohibit the sale,
transfer, exchange, pledge or other disposition of ALZA common stock or any
other securities of ALZA during the period commencing 30 days prior to the
Effective Time and ending on the date on which financial results covering at
least 30 days' combined operations of SEQUUS and ALZA are publicly announced by
ALZA. These agreements are intended to comply with the requirements of
applicable federal securities and tax laws and to help ensure that the merger
will be treated as a pooling of interests for accounting and financial
reporting purposes.
 
The Voting Agreements
 
Each director of SEQUUS, in his or her capacity as a SEQUUS stockholder, has
entered into a voting agreement with ALZA. The directors own of record as of
January 19, 1999 an aggregate of 1,030,556 of the outstanding shares of SEQUUS
common stock, representing approximately 3% of the votes entitled to be cast by
holders of SEQUUS common stock issued and outstanding as of January 19, 1999.
 
Pursuant to the respective voting agreements, each of the SEQUUS directors, in
his or her capacity as a stockholder has agreed to vote his or her shares of
SEQUUS common stock in favor of approval and adoption of the merger agreement
and the merger. Each of the directors has further agreed not to knowingly take
any action which would cause SEQUUS to materially violate its non-solicitation
obligations under the merger agreement.
 
                                       57
<PAGE>
 
                       Description of ALZA Capital Stock
 
The authorized capital stock of ALZA consists of 300,000,000 shares of ALZA
common stock, $.01 par value, of which, as of the date of this proxy
statement/prospectus, approximately 122,490,000 shares are outstanding, and
100,000 shares of preferred stock, $.01 par value, issuable in series, none of
which is outstanding as of the date of this proxy statement/prospectus.
 
ALZA Common Stock
 
Holders of ALZA common stock have one vote per share on all matters submitted
to a vote of stockholders. Stockholders do not have cumulative voting rights.
The holders of ALZA common stock have the right to receive dividends if they
are declared by the ALZA Board and there are sufficient funds to legally pay
dividends, subject to the rights of the holders of any outstanding ALZA
preferred stock to receive preferential dividends. Upon the liquidation of
ALZA, holders of ALZA common stock would share ratably in any assets available
for distribution to stockholders after payment of all obligations of ALZA and
the aggregate liquidation preference (including accrued and unpaid dividends)
of any outstanding ALZA preferred stock.
 
The ALZA common stock is not redeemable and has no preemptive, subscription or
conversion rights. Shares of ALZA common stock currently outstanding are, and
the ALZA common stock to be issued in the merger will be, validly issued, fully
paid and nonassessable.
 
Boston Equiserve is the transfer agent and registrar for the ALZA common stock.
 
ALZA Preferred Stock
 
The authorized ALZA preferred stock is available for issuance from time to time
at the discretion of the ALZA Board without stockholder approval. The ALZA
Board has authority to prescribe for each series of ALZA preferred stock it
establishes the number of shares in that series, the dividend rate, and the
voting rights, conversion privileges, redemption, sinking fund and liquidation
rights, if any, and any other rights, preferences, qualifications and
limitations of the particular series. The issuance of ALZA preferred stock
could decrease the amount of earnings and assets available for distribution to
the holders of ALZA common stock or adversely affect the rights and powers,
including voting rights, of the holders of ALZA common stock. ALZA has no
present plans to issue any ALZA preferred stock.
 
            Comparison of Rights of Holders of ALZA Common Stock and
                         Holders of SEQUUS Common Stock
 
Upon consummation of the merger, the holders of SEQUUS common stock will become
holders of ALZA common stock. Both ALZA and SEQUUS are incorporated in the
State of Delaware. There are certain material differences between the rights
and privileges of the holders of SEQUUS common stock and the holders of ALZA
common stock.
 
Percentage of Voting Stock; Influence Over Affairs. Upon completion of the
merger, the percentage ownership of ALZA by each former SEQUUS stockholder will
be substantially less than that stockholder's current percentage ownership of
SEQUUS. Accordingly, former SEQUUS stockholders will have a significantly
smaller voting influence over the affairs of ALZA than they currently enjoy
over the affairs of SEQUUS.
 
                                       58
<PAGE>
 
Antitakeover Protections.
 
SEQUUS Rights Plan. SEQUUS is subject to certain anti-takeover provisions under
the SEQUUS Rights Plan. The SEQUUS Rights Plan provides that:
 
 . if a third party acquires more than 15% of SEQUUS' common stock, the
   stockholders of SEQUUS, other than such third party, would have the right
   to acquire for a given purchase price a certain number of shares of SEQUUS
   common stock having a value equal to two times that purchase price, or
 
 . if a third party acquires more than 50% of the SEQUUS common stock,
 
then the stockholders of SEQUUS, other than the third party, would have the
right to acquire for that purchase price a certain number of shares of the
common stock of the third party having a value equal to two times the purchase
price. ALZA has not adopted a stockholder rights plan.
 
Bylaw Provisions. The bylaws of ALZA provide that certain transactions
including mergers, substantial asset sales or other business combinations with
third parties who beneficially own 20% or more of the voting interests of ALZA
require the affirmative vote of the holders of at least 80% of the outstanding
shares of stock entitled to vote for the election of directors of ALZA unless:
 
 . the transaction is approved by a majority vote of the directors who are
   unaffiliated with the 20% owner and who were members of the ALZA Board
   immediately prior to the time that the 20% owner involved in the
   transaction became a 20% owner; or
 
 . the aggregate consideration per share to be received in the transaction is
   at least equal to the highest per share price paid by the 20% owner in
   acquiring any of its holdings of the ALZA common stock. SEQUUS does not
   have a similar provision in its bylaws.
 
Classified Board. ALZA's certificate of incorporation provides for three,
evenly divided (to the extent the aggregate number of directors permits)
classes of directors: Class I, Class II and Class III. Only one class of
directors is elected at each annual meeting of the stockholders of ALZA, with
each director elected to a three-year term. SEQUUS' certificate of
incorporation does not provide for classes of directors. All of SEQUUS'
directors are elected at each annual meeting to one-year terms.
 
Action by Written Consent. SEQUUS' bylaws provide that any action that may be
or is required to be taken at any annual meeting or special meeting of the
stockholders of SEQUUS may be taken without a meeting, without prior notice and
without a vote, if a consent in writing, setting forth the action is signed by
the holders of outstanding capital stock having not less than the minimum
number of votes that would be necessary to authorize or take that action.
ALZA's bylaws do not permit the stockholders to take action by written consent.
 
Power of Stockholders to Call Special Stockholders' Meetings. According to the
bylaws of SEQUUS, a special meeting of the SEQUUS stockholders may be called by
the Chairman of the Board of Directors, the Chief Executive Officer, the SEQUUS
Board or the holders of ten percent (10%) of the outstanding capital stock of
SEQUUS. The bylaws of ALZA provide that special meetings of the ALZA
stockholders may be called only by the Chairman of the Board of Directors of
ALZA, the President of ALZA or the ALZA Board.
 
Notification of Stockholder Proposals. While each of ALZA and SEQUUS are
subject to the same rules and regulations of the SEC regarding stockholder
proposals for matters to be voted upon at
 
                                       59
<PAGE>
 
stockholder meetings, the bylaws of ALZA contain the following additional
requirements for any stockholder proposals:
 
 . in the case of nominations for directors of ALZA, any such proposal must
 
  --set forth information regarding the person making such proposal and the
    nominee, and
 
  --include the duly executed written consent of the nominee; and
 
 . in the case of other proposals, the notice shall set forth the name and
   address of the person advancing the proposal, and any material interest of
   that person in the proposal.
 
The differences outlined above between the rights and privileges of the holders
of SEQUUS common stock and the holders of ALZA common stock could, under
certain circumstances, have the effect of reducing the likelihood that the
stockholders of ALZA will receive a significant premium for their shares of
ALZA common stock in connection with hostile takeovers or changes in control or
management of ALZA relative to the likelihood that the stockholders of SEQUUS
will receive a premium in similar circumstances.
 
Stock Exchange Rules. The SEQUUS common stock is currently listed on the Nasdaq
National Market and will cease to trade on the Nasdaq National Market upon
consummation of the merger. The ALZA common stock is traded on the NYSE. There
are material differences between the corporate governance rules of the Nasdaq
National Market and the NYSE.
 
                                       60
<PAGE>
 
          Unaudited Pro Forma Condensed Combined Financial Statements
 
Basis of Presentation
 
The following unaudited pro forma condensed combined financial statements give
effect to the merger using the pooling-of-interests method of accounting, after
giving effect to the pro forma adjustments described in the accompanying notes.
These unaudited pro forma condensed combined financial statements have been
prepared from, and should be read in conjunction with, the historical financial
statements and notes thereto of ALZA and SEQUUS, which are included in ALZA's
Annual Report on Form 10-K/A and Quarterly Reports on Form 10-Q and SEQUUS'
Annual Report on Form 10-K/A and Quarterly Reports on Form 10-Q which are
incorporated by reference in this proxy statement/prospectus. See "Where You
Can Find More Information" on page 16.
 
The unaudited pro forma information is presented for illustrative purposes only
and is not necessarily indicative of the operating results or financial
position that would have occurred had the merger been consummated at the dates
indicated, nor is it necessarily indicative of future operating results or
financial position of the merged companies.
 
Periods Presented
 
The unaudited Pro Forma Condensed Combined Balance Sheet gives effect to the
merger as if it had occurred on September 30, 1998 and combines the unaudited
balance sheets of ALZA and SEQUUS at September 30, 1998. The unaudited Pro
Forma Condensed Combined Statements of Operations give effect to the merger as
if it had occurred at the beginning of the earliest period presented, combining
the results of ALZA and SEQUUS for each year in the three-year period ended
December 31, 1997 and for the nine-month periods ended September 30, 1998 and
1997.
 
Merger-Related Expenses
 
As a result of the merger, ALZA anticipates that a pretax charge of
approximately $15 million for direct merger-related transaction costs will be
recognized in the quarter in which the merger is consummated. These costs
consist primarily of professional and registration fees and have been reflected
as an adjustment to the Pro Forma Combined Condensed Balance Sheet at
September 30, 1998.
 
In addition, the merged companies are expected to incur certain costs in
connection with integrating the operations of ALZA and SEQUUS. ALZA expects to
recognize a pretax charge currently estimated to be in the range of $5 million
to $15 million in the quarter in which the merger is consummated. The charge is
expected to include employee severance costs and costs related to consolidation
of duplicate facilities. This charge is not reflected in the pro forma
financial information.
 
                                       61
<PAGE>
 
              Unaudited Pro Forma Condensed Combined Balance Sheet
                               September 30, 1998
                                 (in millions)
 
<TABLE>
<CAPTION>
                                                           Pro Forma
                                    Historical Historical   Pooling   Pro Forma
                                       ALZA      SEQUUS   Adjustments Combined
                                    ---------- ---------- ----------- ---------
<S>                                 <C>        <C>        <C>         <C>
Assets
Current Assets:
Cash and cash equivalents.........   $   77.3   $   4.4      $ --     $   81.7
Short-term investments............       86.6      16.9        --        103.5
Receivables, net..................      144.1      12.7        --        156.8
Inventories, at cost
  Raw materials...................       12.8       0.8        --         13.6
  Work in process.................        6.7       0.1        --          6.8
  Finished goods..................       19.7       3.1        --         22.8
                                     --------   -------      -----    --------
    Total inventories.............       39.2       4.0        --         43.2
Prepaid expenses and other current
 assets...........................       28.6       1.4        --         30.0
                                     --------   -------      -----    --------
    Total current assets..........      375.8      39.4        --        415.2
                                     --------   -------      -----    --------
Property, plant and equipment.....      459.0      21.5        --        480.5
  Less accumulated depreciation
   and amortization...............     (111.7)    (13.2)       --       (124.9)
                                     --------   -------      -----    --------
  Net property, plant and equip-
   ment...........................      347.3       8.3        --        355.6
Deferred product and license
 acquisition costs................      245.5       --         --        245.5
Investment in long-term
 securities.......................      314.1       --         --        314.1
Other assets......................      197.0       0.2       40.0       237.2
                                     --------   -------      -----    --------
    Total assets..................   $1,479.7   $  47.9      $40.0    $1,567.6
                                     ========   =======      =====    ========
Liabilities and Stockholders'
 Equity
Current Liabilities:
Accounts payable..................   $   25.8   $   5.1      $ --     $   30.9
Accrued liabilities...............       49.3       8.8       15.0        73.1
Other current liabilities.........        5.1       2.0        --          7.1
                                     --------   -------      -----    --------
    Total current liabilities.....       80.2      15.9       15.0       111.1
                                     --------   -------      -----    --------
5% convertible subordinated
 debentures.......................      500.0       --         --        500.0
5 1/4% zero coupon convertible
 subordinated debentures..........      417.3       --         --        417.3
Other long-term liabilities.......       66.3       3.5        --         69.8
Stockholders' Equity:
Common stock and additional paid-
 in capital.......................      421.8     208.2        --        630.0
Accumulated other comprehensive
 income...........................      (16.4)      --         --        (16.4)
Retained earnings (deficit).......       10.5    (179.7)      25.0      (144.2)
                                     --------   -------      -----    --------
Total stockholders' equity........      415.9      28.5       25.0       469.4
                                     --------   -------      -----    --------
    Total liabilities and
     stockholders' equity.........   $1,479.7   $  47.9      $40.0    $1,567.6
                                     ========   =======      =====    ========
</TABLE>
 
                                       62
<PAGE>
 
         Unaudited Pro Forma Condensed Combined Statement of Operations
                  For the nine months ended September 30, 1998
                    (in millions, except per share amounts)
 
<TABLE>
<CAPTION>
                                                            Pro Forma    Pro
                                     Historical Historical   Pooling    Forma
                                        ALZA      SEQUUS   Adjustments Combined
                                     ---------- ---------- ----------- --------
<S>                                  <C>        <C>        <C>         <C>
Revenues
Net sales...........................   $172.0     $ 41.8      $ --      $213.8
Royalties, fees and other...........    164.1        5.0        --       169.1
Research and development............     91.7        --         --        91.7
                                       ------     ------      -----     ------
  Total revenues....................    427.8       46.8        --       474.6
Costs and Expenses
Costs of products shipped...........     92.5        6.6        --        99.1
Research and development............    111.6       27.5        --       139.1
Selling, general and
 administrative.....................     66.3       18.9        --        85.2
                                       ------     ------      -----     ------
  Total expenses....................    270.4       53.0        --       323.4
Operating income (loss).............    157.4       (6.2)       --       151.2
Interest expense....................     42.3        0.4        --        42.7
Interest and other income...........    (18.6)      (1.1)       --       (19.7)
                                       ------     ------      -----     ------
  Net interest and other expense
   (income).........................     23.7       (0.7)       --        23.0
Income (loss) before income taxes...    133.7       (5.5)       --       128.2
Provision for income taxes..........     46.8        --        (2.2)      44.6
                                       ------     ------      -----     ------
  Net income (loss).................   $ 86.9     $ (5.5)     $ 2.2     $ 83.6
                                       ======     ======      =====     ======
Earnings (loss) per share
  Basic.............................   $ 1.01     $(0.18)               $ 0.84
  Diluted...........................   $ 0.97     $(0.18)               $ 0.83
Weighted average shares
  Basic.............................     86.3       31.3                  99.0
  Diluted...........................    113.3       31.3                 101.0
</TABLE>
 
                                       63
<PAGE>
 
         Unaudited Pro Forma Condensed Combined Statement of Operations
                  For the nine months ended September 30, 1997
                    (in millions, except per share amounts)
 
<TABLE>
<CAPTION>
                                                          Pro Forma
                                   Historical Historical   Pooling   Pro Forma
                                      ALZA      SEQUUS   Adjustments Combined
                                   ---------- ---------- ----------- ---------
<S>                                <C>        <C>        <C>         <C>
Revenues
Net sales.........................  $ 100.4     $ 23.6      $--       $ 124.0
Royalties, fees and other.........    131.8        3.7       --         135.5
Research and development..........    106.0        --        --         106.0
                                    -------     ------      ----      -------
  Total revenues..................    338.2       27.3       --         365.5
Costs and Expenses
Costs of products shipped.........     64.9        4.8       --          69.7
Research and development..........    116.5       23.9       --         140.4
Selling, general and
 administrative...................     35.1       19.4       --          54.5
Acquisitions of in-process
 research and development.........     87.0        --        --          87.0
Contribution to Crescendo.........    247.0        --        --         247.0
Asset write-down..................     11.5        --        --          11.5
                                    -------     ------      ----      -------
  Total expenses..................    562.0       48.1       --         610.1
Operating loss....................   (223.8)     (20.8)      --        (244.6)
Interest expense..................     41.3        0.1       --          41.4
Distribution to debenture
 holders..........................      8.0        --        --           8.0
Interest and other income.........    (48.3)      (0.9)      --         (49.2)
                                    -------     ------      ----      -------
  Net interest and other expense
   (income).......................      1.0       (0.8)      --           0.2
Loss before income taxes..........   (224.8)     (20.0)      --        (244.8)
Provision for income taxes........     49.0        --       (8.0)        41.0
                                    -------     ------      ----      -------
Net loss..........................  $(273.8)    $(20.0)     $8.0      $(285.8)
                                    =======     ======      ====      =======
Loss per share
  Basic...........................  $ (3.22)    $(0.66)               $ (2.94)
  Diluted.........................  $ (3.22)    $(0.66)               $ (2.94)
Weighted average shares
  Basic...........................     85.0       30.3                   97.1
  Diluted.........................     85.0       30.3                   97.1
</TABLE>
 
                                       64
<PAGE>
 
         Unaudited Pro Forma Condensed Combined Statement of Operations
                      For the year ended December 31, 1997
                    (in millions, except per share amounts)
 
<TABLE>
<CAPTION>
                                                          Pro Forma
                                   Historical Historical   Pooling   Pro Forma
                                      ALZA      SEQUUS   Adjustments Combined
                                   ---------- ---------- ----------- ---------
<S>                                <C>        <C>        <C>         <C>
Revenues
Net sales.........................  $ 146.1     $ 35.0      $--       $ 181.1
Royalties, fees and other.........    183.3        5.0       --         188.3
Research and development..........    135.0        --        --         135.0
                                    -------     ------      ----      -------
  Total revenues..................    464.4       40.0       --         504.4
Costs and Expenses
Costs of products shipped.........     92.8        7.1       --          99.9
Research and development..........    156.8       32.5       --         189.3
Selling, general and
 administrative...................     51.8       25.2       --          77.0
Acquisitions of in-process
 research and development.........    108.5        --        --         108.5
Contribution to Crescendo.........    247.0        --        --         247.0
Asset write-down..................     11.5        --        --          11.5
                                    -------     ------      ----      -------
  Total expenses..................    668.4       64.8       --         733.2
Operating income (loss)...........   (204.0)     (24.8)      --        (228.8)
Interest expense..................     55.0        0.2       --          55.2
Distribution to debenture
 holders..........................      8.0        --        --           8.0
Interest and other income.........    (55.6)      (1.5)      --         (57.1)
                                    -------     ------      ----      -------
  Net interest and other expense
   (income).......................      7.4       (1.3)      --           6.1
Income (loss) before income
 taxes............................   (211.4)     (23.5)      --        (234.9)
Provision for income taxes........     49.7        --       (9.4)        40.3
                                    -------     ------      ----      -------
Net income (loss).................  $(261.1)    $(23.5)     $9.4      $(275.2)
                                    =======     ======      ====      =======
Earnings (loss) per share
  Basic...........................  $ (3.07)    $(0.78)               $ (2.83)
  Diluted.........................  $ (3.07)    $(0.78)               $ (2.83)
Weighted average shares
  Basic...........................     85.1       30.4                   97.3
  Diluted.........................     85.1       30.4                   97.3
</TABLE>
 
                                       65
<PAGE>
 
         Unaudited Pro Forma Condensed Combined Statement of Operations
                      For the year ended December 31, 1996
                    (in millions, except per share amounts)
 
<TABLE>
<CAPTION>
                                                            Pro Forma
                                     Historical Historical   Pooling   Pro Forma
                                        ALZA      SEQUUS   Adjustments Combined
                                     ---------- ---------- ----------- ---------
<S>                                  <C>        <C>        <C>         <C>
Revenues
Net sales..........................    $108.6     $ 25.5      $--       $134.1
Royalties, fees and other..........     173.3        7.5       --        180.8
Research and development...........     131.2        --        --        131.2
                                       ------     ------      ----      ------
  Total revenues...................     413.1       33.0       --        446.1
Costs and Expenses
Costs of products shipped..........      85.2        4.0       --         89.2
Research and development...........     141.6       27.7       --        169.3
Selling, general and
 administrative....................      47.1       20.3       --         67.4
                                       ------     ------      ----      ------
  Total expenses...................     273.9       52.0       --        325.9
Operating income (loss)............     139.2      (19.0)      --        120.2
Interest expense...................      43.0        --        --         43.0
Interest and other income..........     (52.9)      (1.8)      --        (54.7)
                                       ------     ------      ----      ------
  Net interest and other expense
   (income)........................      (9.9)      (1.8)      --        (11.7)
Income (loss) before income taxes..     149.1      (17.2)      --        131.9
Provision for income taxes.........      56.7        --       (6.9)       49.8
                                       ------     ------      ----      ------
Net income (loss)..................    $ 92.4     $(17.2)     $6.9      $ 82.1
                                       ======     ======      ====      ======
Earnings (loss) per share
  Basic............................    $ 1.10     $(0.59)               $ 0.86
  Diluted..........................    $ 1.08     $(0.59)               $ 0.84
Weighted average shares
  Basic............................      84.2       28.9                  95.8
  Diluted..........................      97.2       28.9                  97.4
</TABLE>
 
                                       66
<PAGE>
 
         Unaudited Pro Forma Condensed Combined Statement of Operations
                      For the year ended December 31, 1995
                    (in millions, except per share amounts)
 
<TABLE>
<CAPTION>
                                                            Pro Forma
                                     Historical Historical   Pooling   Pro Forma
                                        ALZA      SEQUUS   Adjustments Combined
                                     ---------- ---------- ----------- ---------
<S>                                  <C>        <C>        <C>         <C>
Revenues
Net sales..........................    $ 76.9     $  1.9     $  --       $78.8
Royalties, fees and other..........     143.7        0.1        --       143.8
Research and development...........     104.0        --         --       104.0
                                       ------     ------     ------      -----
  Total revenues...................     324.6        2.0        --       326.6
Costs and Expenses
Costs of products shipped..........      65.4        0.5        --        65.9
Research and development...........     103.4       22.6        --       126.0
Selling, general and
 administrative....................      41.1       13.9        --        55.0
                                       ------     ------     ------      -----
  Total expenses...................     209.9       37.0        --       246.9
Operating income (loss)............     114.7      (35.0)       --        79.7
Interest expense...................      23.9        --         --        23.9
Interest and other income..........     (26.0)      (1.4)       --       (27.4)
                                       ------     ------     ------      -----
  Net interest and other expense
   (income)........................      (2.1)      (1.4)       --        (3.5)
Income (loss) before income taxes..     116.8      (33.6)       --        83.2
Provision for income taxes.........      44.4        --       (13.4)      31.0
                                       ------     ------     ------      -----
Net income (loss)..................    $ 72.4     $(33.6)    $ 13.4      $52.2
                                       ======     ======     ======      =====
Earnings (loss) per share
  Basic............................    $ 0.88     $(1.54)                $0.57
  Diluted..........................    $ 0.88     $(1.54)                $0.56
Weighted average shares
  Basic............................      82.3       21.8                  91.0
  Diluted..........................      82.6       21.8                  93.3
</TABLE>
 
                                       67
<PAGE>
 
Notes to Unaudited Pro Forma Condensed Combined Financial Statements
 
NOTE 1. Pro Forma Combined Earnings (Loss) Per Share
 
Under the merger agreement, each outstanding share of SEQUUS common stock will
be converted into .40 of a share of ALZA common stock. This exchange ratio was
used in computing share and per share amounts in the accompanying unaudited pro
forma condensed combined financial statements.
 
NOTE 2. Merger Costs
 
The Pro Forma Condensed Combined Balance Sheet at September 30, 1998 reflects
an adjustment of $15 million for direct merger-related transaction costs,
primarily consisting of professional and registration fees.
 
NOTE 3. Income Taxes
 
Pro forma adjustments have been made to reduce valuation allowances previously
provided by SEQUUS against deferred tax assets attributable to its net
operating loss carry-forwards and temporary differences. Because ALZA and
SEQUUS will file consolidated income tax returns subsequent to the merger, the
SEQUUS temporary differences will be realized against combined future taxable
income. The SEQUUS net operating loss carryforwards are subject to certain
annual limitations because of the change of ownership rules under federal and
state tax law. Because of ALZA's history of taxable income, and its ability to
utilize such loss carryforwards against combined future taxable income through
appropriate tax planning, the valuation allowance against the deferred tax
asset for such carryforwards has been reduced to reflect the anticipated
benefit available under the annual limitations imposed by the change of
ownership provisions.
 
NOTE 4. 1997 Charges
 
The Pro Forma Condensed Combined Statement of Operations for the year ended
December 31, 1997 reflects a total of $368.7 million (or pro forma $3.77 per
share, diluted) of charges, net of a tax benefit of $8.1 million, including a
$247.0 million charge and $8.0 million of interest expense related to ALZA's
distribution of shares of Crescendo, $108.5 million for acquired in-process
research and development, an asset write-down of $11.5 million and costs of
$1.8 million related to workforce reductions. Pro forma combined net income
excluding these items would have been $93.4 million (or pro forma $0.94 per
share, diluted).
 
The Pro Forma Condensed Combined Statement of Operations for the nine months
ended September 30, 1997 reflects a total of $353.5 million (or pro forma $3.63
per share, diluted) of charges including a $247.0 million charge and $8.0
million of interest expense related to ALZA's distribution of shares of
Crescendo, $87.0 million for acquired in-process research and development, and
an asset write-down of $11.5 million. Pro forma combined net income excluding
these items would have been $67.8 million (or pro forma $0.69 per share,
diluted).
 
                                       68
<PAGE>
 
                                    Experts
 
Ernst & Young LLP, independent auditors, have audited the ALZA Corporation
consolidated financial statements at December 31, 1997 and 1996, and for each
of the three years in the period ended December 31, 1997, incorporated by
reference in the Proxy Statement of SEQUUS Pharmaceuticals, Inc., which is
referred to and made a part of this Prospectus and Registration Statement as
set forth in their report which is also incorporated by reference. The ALZA
Corporation consolidated financial statements are incorporated by reference in
reliance on their report, given on their authority as experts in accounting and
auditing.
 
Ernst & Young LLP, independent auditors, have audited the SEQUUS
Pharmaceuticals, Inc. financial statements at December 31, 1997 and 1996, and
for each of the three years in the period ended December 31, 1997, incorporated
by reference in the Proxy Statement of SEQUUS Pharmaceuticals, Inc., which is
referred to and made a part of this Prospectus and Registration Statement as
set forth in their report which is also incorporated by reference. The SEQUUS
Pharmaceuticals, Inc. financial statements are incorporated by reference in
reliance on their report, given on their authority as experts in accounting and
auditing.
 
                                 Legal Matters
 
The validity of the ALZA common stock to be issued by ALZA in connection with
the merger will be passed upon by Heller Ehrman, Palo Alto, California. Julian
N. Stern, a director and the Secretary of ALZA, is a shareholder of Heller
Ehrman. As of February 10, 1999, attorneys at Heller Ehrman involved in the
representation of ALZA owned beneficially 101,668 shares of ALZA common stock,
including options or warrants to purchase ALZA common stock.
 
Heller Ehrman will provide an opinion to ALZA and Cooley Godward will provide
an opinion to SEQUUS as to the qualification of the merger as a reorganization
under the Internal Revenue Code.
 
                             Stockholder Proposals
 
SEQUUS will hold a 1999 Annual Meeting of Stockholders only if the merger is
not consummated. No stockholder proposals were received by the Secretary of
SEQUUS for inclusion in the SEQUUS 1999 proxy materials.
 
                                       69
<PAGE>
 
                                                                        ANNEX A
 
 
                         AGREEMENT AND PLAN OF MERGER
 
                                 BY AND AMONG
 
                               ALZA CORPORATION,
 
                           ARGYLE ACQUISITION CORP.
 
                                      AND
 
                         SEQUUS PHARMACEUTICALS, INC.
 
                          DATED AS OF OCTOBER 4, 1998
 
 
 
<PAGE>
 
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                                                           Page
                                                                           ----
 <C>         <S>                                                           <C>
 ARTICLE I   THE MERGER..................................................    1
    1.1      The Merger..................................................    1
    1.2      Closing; Effective Time.....................................    1
    1.3      Effects of the Merger.......................................    2
    1.4      Certificate of Incorporation; Bylaws........................    2
    1.5      Directors and Officers of the Surviving Corporation.........    2
 ARTICLE II  CONVERSION OF SHARES........................................    2
    2.1      Conversion of Stock.........................................    2
    2.2      SEQUUS Options and Warrants; SEQUUS Stock Purchase Plan.....    3
    2.3      Exchange of Stock Certificates..............................    5
    2.4      Lost, Stolen or Destroyed Certificates......................    6
    2.5      Tax Consequences............................................    6
 ARTICLE III REPRESENTATIONS AND WARRANTIES OF SEQUUS....................    6
    3.1      Organization, Etc. .........................................    6
    3.2      Authority Relative to This Agreement........................    7
    3.3      No Violations, Etc. ........................................    8
    3.4      Board Recommendation........................................    8
    3.5      Fairness Opinion............................................    9
    3.6      Capitalization..............................................    9
    3.7      SEC Filings.................................................   10
    3.8      Financial Statements........................................   10
    3.9      Absence of Undisclosed Liabilities..........................   10
    3.10     Absence of Changes or Events................................   10
    3.11     Intentionally Omitted.......................................   12
    3.12     Litigation..................................................   12
    3.13     Insurance...................................................   12
    3.14     Contracts and Commitments...................................   12
    3.15     Labor Matters; Employment and Labor Contracts...............   14
    3.16     Compliance with Laws........................................   14
    3.17     Intellectual Property Rights................................   15
    3.18     Taxes.......................................................   16
    3.19     Employee Benefit Plans; ERISA...............................   17
    3.20     Environmental Matters.......................................   20
    3.21     Officer's Certificate as to Tax Matters.....................   22
    3.22     Affiliates..................................................   22
    3.23     Finders or Brokers..........................................   22
    3.24     Registration Statement; Proxy Statement/Prospectus..........   22
    3.25     Pooling of Interests........................................   22
    3.26     Title to Property...........................................   23
    3.27     Year 2000 Compliance........................................   23
 ARTICLE IV  REPRESENTATIONS AND WARRANTIES OF ALZA AND MERGER SUB.......   23
    4.1      Organization, Etc. .........................................   24
    4.2      Authority Relative to This Agreement........................   24
    4.3      No Violations, Etc. ........................................   25
    4.4      Capitalization..............................................   25
    4.5      Registration Statement; Proxy Statement/Prospectus..........   25
    4.6      SEC Filings.................................................   26
    4.7      Compliance with Laws........................................   26
</TABLE>
 
                                       i
<PAGE>
 
                         TABLE OF CONTENTS--(Continued)
 
<TABLE>
<CAPTION>
                                                                           Page
                                                                           ----
 <C>          <S>                                                          <C>
    4.8       Financial Statements......................................    26
    4.9       Absence of Undisclosed Liabilities........................    26
    4.10      Absence of Changes or Events..............................    27
    4.11      Litigation................................................    27
    4.12      Officer's Certificate as to Tax Matters...................    27
    4.13      Pooling of Interests......................................    27
    4.14      Taxes.....................................................    27
    4.15      Contracts and Commitments.................................    27
    4.16      Intellectual Property Rights..............................    28
    4.17      FDA Matters...............................................    28
 ARTICLE V    COVENANTS.................................................    29
    5.1       Conduct of Business During Interim Period.................    29
    5.2       No Solicitation...........................................    31
    5.3       Access to Information.....................................    32
              Special Meeting; Registration Statement; Board
    5.4        Recommendation...........................................    33
    5.5       Commercially Reasonable Efforts...........................    33
    5.6       Public Announcements......................................    34
    5.7       Notification of Certain Matters...........................    34
    5.8       Indemnification...........................................    35
    5.9       Expenses..................................................    36
    5.10      Pooling of Interests Accounting...........................    36
    5.11      Affiliate Agreements......................................    37
    5.12      NYSE Listings.............................................    37
    5.13      Resignation of Directors and Officers.....................    37
    5.14      Consents of ALZA's and SEQUUS' Accountants................    37
    5.15      Stock Options and Warrants................................    38
    5.16      Board of Directors........................................    38
    5.17      Intentionally Omitted.....................................    38
    5.18      SEC Filings...............................................    38
    5.19      Employee Benefit Matters..................................    38
 ARTICLE VI   CONDITIONS TO THE OBLIGATIONS OF EACH PARTY...............    40
    6.1       Registration Statement....................................    40
    6.2       Shareholder Approval......................................    40
    6.3       Listing of Additional Shares..............................    40
    6.4       Governmental Clearances...................................    40
    6.5       Tax Matters...............................................    40
    6.6       Statute or Decree.........................................    40
    6.7       Pooling...................................................    41
 ARTICLE VII  CONDITIONS TO THE OBLIGATIONS OF SEQUUS AND ALZA..........    41
    7.1       Additional Conditions to the Obligation of SEQUUS.........    41
              Additional Conditions to the Obligation of ALZA And Merger
    7.2        Sub......................................................    41
 ARTICLE VIII TERMINATION...............................................    42
    8.1       Termination...............................................    42
    8.2       Termination by ALZA.......................................    43
    8.3       Termination by SEQUUS.....................................    44
    8.4       Procedure for Termination.................................    44
    8.5       Effect of Termination.....................................    44
</TABLE>
 
                                       ii
<PAGE>
 
                         TABLE OF CONTENTS--(Continued)
 
<TABLE>
<CAPTION>
                                                                            Page
                                                                            ----
 <C>        <S>                                                             <C>
 ARTICLE IX MISCELLANEOUS.................................................   45
    9.1     Amendment and Modification....................................   45
    9.2     Waiver of Compliance; Consents................................   45
    9.3     Survival; Investigations......................................   45
    9.4     Notices.......................................................   46
    9.5     Assignment; Third Party Beneficiaries.........................   46
    9.6     Governing Law.................................................   47
    9.7     Counterparts..................................................   47
    9.8     Severability..................................................   47
    9.9     Interpretation................................................   47
    9.10    Entire Agreement..............................................   47
    9.11    Definition of Law.............................................   47
    9.12    Rules of Construction.........................................   47
</TABLE>
 
<TABLE>
<S>            <C> <C>
Exhibits
  Exhibit A--
   Certificate
   of Merger
  Exhibit B--
   Form of
   SEQUUS
   Affiliates
   Agreement
  Exhibit C--
   Form of
   ALZA
   Affiliates
   Agreement
</TABLE>
 
                                      iii
<PAGE>
 
                             INDEX OF DEFINED TERMS
 
<TABLE>
<S>                                                         <C>
"Acquisition Proposal"..................................... Section 5.2(c)
"Action"................................................... Section 3.12(a)
"Affiliates"............................................... Section 3.22
"Antitrust Division"....................................... Section 5.5(a)
"ALZA"..................................................... Preamble
"ALZA Balance Sheet"....................................... Section 4.8
"ALZA Closing Value"....................................... Section 2.1(f)
"ALZA Common Stock"........................................ Recitals
"ALZA Contract"............................................ Section 4.15(b)
"ALZA Disclosure Statement"................................ Article IV
"ALZA Exchange Options".................................... Section 2.2
"ALZA Financial Statements"................................ Section 4.8
"ALZA IP Rights............................................ Section 4.16(a)
"ALZA Material Adverse Effect"............................. Section 4.1
"ALZA Purchase Plan........................................ Section 2.2(b)
"ALZA SEC Reports"......................................... Section 4.6(a)
"ALZA Subsidiaries"........................................ Section 4.1
"Business Combination"..................................... Section 5.1(b)
"CERCLA"................................................... Section 3.20(a)(iii)
"Certificate of Merger".................................... Section 1.2
"Closing".................................................. Section 1.2
"Closing Date"............................................. Section 1.2
"COBRA".................................................... Section 3.15(b)
"Code"..................................................... Recitals
"Confidentiality Agreements"............................... Section 5.3
"Contractor"............................................... Section 3.20(a)(i)
"CSA"...................................................... Section 3.16(b)
"DEA"...................................................... Section 3.16(b)
"Delaware Law"............................................. Section 1.1
"Effective Time"........................................... Section 1.2
"Employee Benefit Plans"................................... Section 3.19(a)
"Environment".............................................. Section 3.20(a)(ii)
"Environmental Law"........................................ Section 3.20(a)(iii)
"Environmental Permit"..................................... Section 3.20(a)(iv)
"ERISA".................................................... Section 3.19(a)
"ERISA Affiliate".......................................... Section 3.19(a)
"Exchange Act"............................................. Section 3.3
"Exchange Agent"........................................... Section 2.3(a)
"Exchange Multiple"........................................ Section 2.1(g)
"Exchange Quotient"........................................ Section 2.1(g)
"Exchange Ratio"........................................... Section 2.1(a)
"FDA"...................................................... Section 3.16(b)
"FDCA"..................................................... Section 3.16(b)
"Foreign Plan"............................................. Section 3.19(n)
"FTC"...................................................... Section 5.5(a)
"GAAP"..................................................... Section 3.8
"Government Entity"........................................ Section 3.3
"group health plan"........................................ Section 3.19(k)
"Hazardous Material"....................................... Section 3.20(a)(v)
"Holder"................................................... Section 2.3(c)
</TABLE>
 
                                       iv
<PAGE>
 
                      INDEX OF DEFINED TERMS--(Continued)
 
<TABLE>
<S>                                                          <C>
"HSR Act"................................................... Section 3.3
"Identified Products"....................................... Section 4.15(a)
"Identified Technology"..................................... Section 4.16(b)
"Indemnified Parties"....................................... Section 5.8(b)
"IRS"....................................................... Section 3.19(d)
"law"....................................................... Section 9.11
"Material Products"......................................... Section 5.1(a)(x)
"Merger".................................................... Recitals
"Merger Sub"................................................ Preamble
"Merger Sub Common Stock"................................... Section 2.1(d)
"NYSE"...................................................... Section 2.1(f)
"Pension Plans"............................................. Section 3.19(a)
"Person".................................................... Section 2.1(g)
"Potential Acquiror"........................................ Section 5.2(a)
"Proxy Statement/Prospectus"................................ Section 3.24
"Real Property"............................................. Section 3.20(b)(iv)
"Reference Date"............................................ Section 3.8
"Registration Statement".................................... Section 3.24
"SEC"....................................................... Section 3.7(a)
"Securities Act"............................................ Section 3.7(a)
"SEQUUS".................................................... Preamble
"SEQUUS Balance Sheet"...................................... Section 3.8
"SEQUUS Certificate"........................................ Section 2.3(c)
"SEQUUS Common Stock"....................................... Recitals
"SEQUUS Contract"........................................... Section 3.14(b)
"SEQUUS Disclosure Statement"............................... Article III
"SEQUUS Purchase Plan"...................................... Section 2.2(b)
"SEQUUS Financial Statements"............................... Section 3.8
"SEQUUS IP Rights".......................................... Section 3.17(a)
"SEQUUS Material Adverse Effect"............................ Section 3.1(a)
"SEQUUS Negative Vote"...................................... Section 8.1(d)
"SEQUUS Options"............................................ Section 2.2
"SEQUUS Preferred Stock".................................... Section 3.6(a)
"SEQUUS Rights"............................................. Section 2.1(a)
"SEQUUS Rights Plan"........................................ Section 2.1(a)
"SEQUUS SEC Reports"........................................ Section 3.7(a)
"SEQUUS Special Meeting".................................... Section 5.4(a)
"SEQUUS Stock Plan"......................................... Section 2.2
"Stock Option Agreement".................................... Section 3.2
"Subsidiary"................................................ Section 2.1(g)
"Superior Proposal"......................................... Section 5.2(d)
"Surviving Corporation"..................................... Section 1.1
"Tax" or "Taxes"............................................ Section 3.18(a)
"Tax Return"................................................ Section 3.18(a)
"Voting Agreements"......................................... Section 3.6(b)
"WARN"...................................................... Section 5.19(e)
"Welfare Plans"............................................. Section 3.19(a)
"Year 2000 Compliant"....................................... Section 3.27
</TABLE>
 
                                       v
<PAGE>
 
                          AGREEMENT AND PLAN OF MERGER
 
This AGREEMENT AND PLAN OF MERGER (this "Agreement") is made and entered into
as of October 4, 1998 by and among ALZA Corporation, a Delaware corporation
("ALZA"), Argyle Acquisition Corp., a Delaware corporation and wholly-owned
subsidiary of ALZA ("Merger Sub"), and SEQUUS Pharmaceuticals, Inc., a Delaware
corporation ("SEQUUS"), with respect to the following facts:
 
A. The respective boards of directors of ALZA, Merger Sub and SEQUUS have
approved and declared advisable the Merger of Merger Sub with and into SEQUUS
(the "Merger"), upon the terms and subject to the conditions set forth herein,
and have determined that the Merger is fair to, and in the best interests of,
their respective stockholders.
 
B. Pursuant to the Merger, among other things, the outstanding shares of SEQUUS
Common Stock, $.0001 par value ("SEQUUS Common Stock"), will be converted into
shares of ALZA Common Stock, $.01 par value ("ALZA Common Stock"), at the rate
set forth herein.
 
C. For United States federal income tax purposes, it is intended that the
Merger will qualify as a reorganization under the provisions of Section 368(a)
of the Internal Revenue Code of 1986, as amended (the "Code").
 
D. For financial accounting purposes, it is intended that the Merger will be
accounted for as a pooling of interests transaction.
 
The parties agree as follows:
 
                                   ARTICLE I
 
                                   THE MERGER
 
1.1 The Merger. At the Effective Time (as defined in Section 1.2) and subject
to and upon the terms and conditions of this Agreement and the applicable
provisions of Delaware General Corporation Law (the "Delaware Law"), (i) Merger
Sub shall be merged with and into SEQUUS, (ii) the separate corporate existence
of Merger Sub shall cease, and (iii) SEQUUS shall be the surviving corporation.
SEQUUS, as the surviving corporation after the Merger, is hereinafter sometimes
referred to as the "Surviving Corporation."
 
1.2 Closing; Effective Time. The closing of the Merger and the other
transactions contemplated hereby (the "Closing") will take place at 10:00 a.m.,
local time, on a date to be specified by the parties (the "Closing Date"),
which shall be no later than the first business day after satisfaction or
waiver of the conditions set forth in Articles VI and VII, unless another time
or date is agreed to by the parties hereto. The Closing shall take place at the
offices of Heller Ehrman White & McAuliffe, 525 University Avenue, Palo Alto,
California, or at such other location as the parties hereto shall mutually
agree. At the Closing, the parties hereto shall cause the Merger to be
consummated by filing a certificate of Merger substantially in the form of
Exhibit A (the "Certificate of Merger") with the Secretary of State of the
State of Delaware, in accordance with the relevant provisions of the Delaware
Law (the time of such filing, or such later time as may be agreed in writing by
the parties and specified in the Certificate of Merger, being the "Effective
Time").
 
                                      A-1
<PAGE>
 
1.3 Effects of the Merger. The effects of the Merger shall be as provided in
this Agreement, the Certificate of Merger and the applicable provisions of the
Delaware Law. Without limiting the foregoing, at the Effective Time all the
property, rights, privileges, powers and franchises of SEQUUS and Merger Sub
shall vest in the Surviving Corporation, and all debts, liabilities and duties
of SEQUUS and Merger Sub shall become the debts, liabilities and duties of the
Surviving Corporation.
 
1.4 Certificate of Incorporation; Bylaws.
 
(a) Subject to Section 5.8, from and after the Effective Time, the certificate
of incorporation of Merger Sub, as in effect immediately prior to the Effective
Time, shall be the certificate of incorporation of the Surviving Corporation;
provided, however, that at the Effective Time the certificate of incorporation
of Merger Sub shall be amended so that the name of Surviving Corporation shall
be "SEQUUS Pharmaceuticals, Inc."
 
(b) Subject to Section 5.8, from and after the Effective Time, the bylaws of
Merger Sub, as in effect immediately prior to the Effective Time, shall be the
bylaws of the Surviving Corporation.
 
1.5 Directors and Officers of the Surviving Corporation. The directors and
officers of Merger Sub immediately prior to the Effective Time shall serve as
the directors and officers of the Surviving Corporation, until their respective
successors are duly elected or appointed and qualified.
 
                                   ARTICLE II
 
                              CONVERSION OF SHARES
 
2.1 Conversion of Stock. Pursuant to the Merger, and without any action on the
part of the holders of any outstanding shares of capital stock or other
securities of SEQUUS or Merger Sub:
 
(a) As of the Effective Time, each share of SEQUUS Common Stock, together with
the rights (the "SEQUUS Rights") associated with each such share issued in
connection with SEQUUS' Rights Agreement (the "SEQUUS Rights Plan") dated April
17, 1997 between SEQUUS and ChaseMellon Shareholders Services, L.L.C., issued
and outstanding immediately prior to the Effective Time (other than shares of
SEQUUS Common Stock to be canceled pursuant to Section 2.1(c)) shall be
automatically converted into 0.40 (the "Exchange Ratio") of a fully paid and
nonassessable share of ALZA Common Stock.
 
(b) As of the Effective Time, each holder of a certificate or certificates
which immediately prior to the Effective Time represented outstanding shares of
SEQUUS Common Stock shall cease to have any rights with respect thereto, except
the right to receive (i) a certificate (or direct registration) representing
the number of whole shares of ALZA Common Stock into which such shares have
been converted, and (ii) cash in lieu of fractional shares of ALZA Common Stock
in accordance with Section 2.1(f), without interest.
 
(c) As of the Effective Time, each share of SEQUUS Common Stock held of record
immediately prior to the Effective Time by SEQUUS, Merger Sub, ALZA or any
Subsidiary (as defined in Section 2.1(g)) of SEQUUS or of ALZA shall be
canceled and extinguished without any conversion thereof.
 
                                      A-2
<PAGE>
 
(d) As of the Effective Time, each share of Common Stock, $.0001 par value, of
Merger Sub (the "Merger Sub Common Stock") issued and outstanding immediately
prior to the Effective Time shall be canceled, extinguished and automatically
converted into one validly issued, fully paid and nonassessable share of Common
Stock, $.0001 par value, of the Surviving Corporation. Each certificate
evidencing ownership of a number of shares of Merger Sub Common Stock shall be
deemed to evidence ownership of the same number of shares of Common Stock,
$.0001 par value, of the Surviving Corporation.
 
(e) The Exchange Ratio shall be adjusted, or ALZA shall make appropriate
provision, to reflect appropriately the effect of any stock split, reverse
stock split, stock dividend (including any dividend or distribution of
securities convertible into ALZA Common Stock or SEQUUS Common Stock),
extraordinary dividend or distribution, reorganization, recapitalization or
other like change with respect to ALZA Common Stock or (subject to Section 5.1)
SEQUUS Common Stock occurring or having a record date or an effective date on
or after the date hereof and prior to the Effective Time.
 
(f) No fraction of a share of ALZA Common Stock will be issued by virtue of the
Merger. Instead, each holder of shares of SEQUUS Common Stock who would
otherwise be entitled to a fraction of a share of ALZA Common Stock (after
aggregating all fractional shares of ALZA Common Stock to be received by such
holder) shall receive from ALZA an amount of cash (rounded down to the nearest
whole cent) equal to the product of (i) such fraction, multiplied by (ii) the
ALZA Closing Value. For the purposes of this Agreement, "ALZA Closing Value"
shall mean the closing price per share of ALZA Common Stock as reported on the
New York Stock Exchange ("NYSE") Composite Tape on the trading day immediately
preceding the Effective Time.
 
(g) For the purposes of this Agreement, the "Exchange Multiple" of any quantity
means the product obtained from multiplying such quantity by the Exchange
Ratio, and the "Exchange Quotient" of any quantity means the quotient obtained
from dividing such quantity by the Exchange Ratio. For purposes of this
Agreement, the term "Subsidiary", when used with respect to any Person, means
any corporation or other organization, whether incorporated or unincorporated,
of which (A) at least a majority of the securities or other interests having by
their terms ordinary voting power to elect a majority of the board of directors
or others performing similar functions with respect to such corporation or
other organization is directly or indirectly owned or controlled by such Person
(through ownership of securities, by contract or otherwise) or (B) such Person
or any Subsidiary of such Person is a general partner of any general
partnership or a manager of any limited liability company. For the purposes of
this Agreement, the term "Person" means any individual, organization,
corporation, partnership, joint venture, limited liability company, trust or
entity of any kind.
 
2.2 SEQUUS Options and Warrants; SEQUUS Purchase Plan.
 
(a) As of the Effective Time, ALZA shall, to the full extent permitted by
applicable law, assume all of the stock options of SEQUUS outstanding
immediately prior to the Effective Time under the SEQUUS Stock Plans (as
defined below) (the "SEQUUS Options"). As of the Effective Time, ALZA shall
assume in accordance with their terms, all the warrants to purchase SEQUUS
Common Stock dated May 19, 1995 (which expire on May 25, 1999) outstanding
immediately prior to the Effective Time (the "Warrants"). For purposes of this
Agreement, "SEQUUS Stock Plans" means
 
                                      A-3
<PAGE>
 
SEQUUS' 1987 Employee Stock Option Plan, 1987 Consultant Stock Option Plan,
1990 Director Stock Option Plan and Equity Incentive Plan (in each case, as
amended prior to the date hereof). Each SEQUUS Option, whether or not
exercisable at the Effective Time, to the full extent permitted by applicable
law, shall be assumed by ALZA in such a manner that it shall be exercisable
upon the same terms and conditions as under the SEQUUS Stock Plan pursuant to
which it was granted and the applicable option agreement issued thereunder
(including, without limitation, the lapse of all rights of repurchase with
respect to such SEQUUS Options granted under the 1987 Employee Stock Option
Plan and the 1987 Consultant Stock Option Plan in accordance with the
resolutions of the SEQUUS board of directors approved on March 10, 1994, and
June 19, 1995); and each Warrant shall be assumed by ALZA in the manner
provided for in such Warrant so that it shall be exercisable on the terms and
conditions provided in such Warrant; provided that (i) each such option
thereafter shall be exercisable for a number of shares of ALZA Common Stock
(rounded down to the nearest whole share) equal to the Exchange Multiple of the
number of shares of SEQUUS Common Stock subject to such option, and (ii) the
price per share of ALZA Common Stock thereafter shall equal the Exchange
Quotient (rounded up to the nearest whole cent) of the option price per share
of SEQUUS Common Stock subject to such option in effect immediately prior to
the Effective Time (the "ALZA Exchange Options"); provided, further that (i)
each such Warrant thereafter shall be exercisable for a number of shares of
ALZA Common Stock equal to the Exchange Multiple of the number of shares of
SEQUUS Common Stock subject to such Warrant, and (ii) the price per share of
ALZA Common Stock thereafter shall equal the Exchange Quotient of the Warrant
price per share of SEQUUS Common Stock subject to such Warrant in effect
immediately prior to the Effective Time. Prior to the Effective Time, SEQUUS
shall make all adjustments provided for in the SEQUUS Stock Plans with respect
to the SEQUUS Options to facilitate the implementation of the provisions of
this Section 2.2. It is intended that SEQUUS Options assumed by ALZA shall
qualify following the Effective Time as incentive stock options, as defined in
Section 422 of the Code, to the extent SEQUUS Options qualified as incentive
stock options immediately prior to the Effective Time, and the provisions of
this Section 2.2(a) shall be applied in a manner that is consistent with such
intent.
 
(b) SEQUUS shall amend the SEQUUS Employee Stock Purchase Plan (the "SEQUUS
Purchase Plan") so that as of the Effective Time: (i) the SEQUUS Purchase Plan
shall provide that no additional purchase rights shall be issued under it; (ii)
the purchase dates of each then-outstanding purchase right granted under the
SEQUUS Purchase Plan shall conform to the purchase dates then in effect under
the ALZA Amended and Restated Employee Stock Purchase Plan (the "ALZA Purchase
Plan"); and (iii) each purchase right granted under the SEQUUS Purchase Plan
shall terminate (if it has not previously terminated by its terms) on the
purchase date under the ALZA Purchase Plan immediately preceding August 1,
1999, or if earlier, on the date that the holder thereof enrolls in the ALZA
Purchase Plan. As of the Effective Time, each then-outstanding purchase right
granted under the SEQUUS Purchase Plan shall be assumed by ALZA in such a
manner that it shall be exercisable upon the same terms and conditions (as
amended as described above) as under the SEQUUS Purchase Plan immediately
before the Effective Time; provided that each such purchase right shall
thereafter be exercisable for whole shares of ALZA Common Stock (rounded down
to the nearest whole share) equal to the Exchange Multiple of the number of
shares of SEQUUS Common Stock for which such purchase right would otherwise
have been exercisable determined as of the relevant grant date under the SEQUUS
Purchase Plan at a purchase price per share equal to 85% of the lower of: (i)
the Exchange Quotient (rounded up to the nearest whole cent) of the fair market
value of a
 
                                      A-4
<PAGE>
 
share of SEQUUS Common Stock on the relevant grant date under the SEQUUS
Purchase Plan or (ii) the fair market value of a share of a ALZA Common Stock
on the relevant purchase date.
 
2.3 Exchange of Stock Certificates.
 
(a) At or prior to the Effective Time, ALZA shall enter into an agreement with
a bank or trust company selected by ALZA and reasonably acceptable to SEQUUS to
act as the exchange agent for the Merger (the "Exchange Agent").
 
(b) At or prior to the Effective Time, ALZA shall supply or cause to be
supplied to or for the account of the Exchange Agent in trust for the benefit
of the holders of SEQUUS Common Stock, for exchange pursuant to this Section
2.3, (i) certificates (or direct registration) evidencing the shares of ALZA
Common Stock issuable pursuant to Section 2.1 to be exchanged for outstanding
shares of SEQUUS Common Stock, and (ii) cash in an aggregate amount sufficient
to make the payments in lieu of fractional shares provided for in Section
2.1(f).
 
(c) Promptly after the Effective Time, ALZA shall mail or shall cause to be
mailed to each Holder a letter of transmittal in customary form (which shall
specify that delivery shall be effected, and risk of loss and title to the
SEQUUS Certificates shall pass, only upon proper delivery of the SEQUUS
Certificates to the Exchange Agent) and instructions for surrender of the
SEQUUS Certificates. Upon surrender to the Exchange Agent of a SEQUUS
Certificate, together with such letter of transmittal duly executed, the Holder
shall be entitled to receive in exchange therefor: (i) certificates evidencing
that number of shares of ALZA Common Stock issuable to such Holder in
accordance with this Article II; (ii) any dividends or other distributions that
such Holder has the right to receive pursuant to Section 2.3(d); and (iii) cash
in respect of fractional shares as provided in Section 2.1(f), and such SEQUUS
Certificate so surrendered shall forthwith be canceled. No certificate
representing shares of ALZA Common Stock will be issued to a Person who is not
the registered owner of a surrendered SEQUUS Certificate unless (i) the SEQUUS
Certificate so surrendered has been properly endorsed or otherwise is in proper
form for transfer, and (ii) such Person shall either (A) pay any transfer or
other tax required by reason of such issuance or (B) establish to the
reasonable satisfaction of the Surviving Corporation that such tax has been
paid or is not applicable. Until surrendered in accordance with the provisions
of this Section 2.3, from and after the Effective Time, each SEQUUS Certificate
shall be deemed to represent, for all purposes other than payment of dividends,
the right to receive a certificate representing the number of full shares of
ALZA Common Stock as determined in accordance with this Article II and cash in
lieu of fractional shares as provided in Section 2.1(f). For purposes of this
Agreement, "SEQUUS Certificate" means a certificate which immediately prior to
the Effective Time represented shares of SEQUUS Common Stock, and "Holder"
means a person who holds one or more SEQUUS Certificates as of the Effective
Time.
 
(d) No dividend or other distribution declared with respect to ALZA Common
Stock with a record date after the Effective Time will be paid to Holders of
unsurrendered SEQUUS Certificates until such Holders surrender their SEQUUS
Certificates. Upon the surrender of such SEQUUS Certificates, there shall be
paid to such Holders, promptly after such surrender, the amount of dividends or
other distributions, excluding interest, declared with a record date after the
Effective Time and not paid because of the failure to surrender SEQUUS
Certificates for exchange.
 
                                      A-5
<PAGE>
 
(e) Notwithstanding anything to the contrary in this Agreement, neither the
Exchange Agent, ALZA, the Surviving Corporation nor any party hereto shall be
liable to any holder of shares of SEQUUS Common Stock for shares of ALZA Common
Stock or cash in lieu of fractional shares properly delivered to a public
official pursuant to any applicable abandoned property, escheat or similar law.
 
2.4 Lost, Stolen or Destroyed Certificates. In the event that any SEQUUS
Certificates shall have been lost, stolen or destroyed, the Exchange Agent
shall issue and pay in respect of such lost, stolen or destroyed SEQUUS
Certificates, upon the making of an affidavit of that fact by the holder
thereof, certificates representing the shares of ALZA Common Stock as may be
required pursuant to Section 2.1 and cash in lieu of fractional shares, if any,
as may be required pursuant to Section 2.1(f) and any dividends or
distributions payable pursuant to Section 2.3(d); provided, however, that ALZA
may, in its discretion and as a condition precedent to the issuance thereof,
require the owner of such lost, stolen or destroyed SEQUUS Certificates to
deliver a bond in such sum as it may reasonably direct as indemnity against any
claim that may be made against ALZA or the Exchange Agent with respect to the
SEQUUS Certificates alleged to have been lost, stolen or destroyed.
 
2.5 Tax Consequences. For United States federal income tax purposes, it is
intended by the parties hereto that the Merger qualify as a reorganization
within the meaning of Section 368(a) of the Code.
 
                                  ARTICLE III
 
                    REPRESENTATIONS AND WARRANTIES OF SEQUUS
 
SEQUUS makes to ALZA and Merger Sub the representations and warranties
contained in this Article III, in each case subject to the exceptions set forth
in the disclosure statement, dated as of the date hereof, delivered by SEQUUS
to ALZA prior to the execution of this Agreement (the "SEQUUS Disclosure
Statement"). The SEQUUS Disclosure Statement shall be arranged in schedules
corresponding to the numbered Sections of this Article III, and the disclosure
in any Section of the SEQUUS Disclosure Statement shall qualify only the
corresponding Section of this Article III, unless it is reasonably apparent
that the disclosed contract, event, fact, circumstance or other matter could
relate to other representations or warranties or the matters covered thereby.
 
3.1 Organization, Etc.
 
(a) Each of SEQUUS and its Subsidiaries is a corporation duly organized,
validly existing and in good standing under the laws of the jurisdiction of its
incorporation, and has all requisite corporate power and authority to own,
lease and operate its properties and to carry on its business as now being
conducted. Each of SEQUUS and its Subsidiaries is duly qualified as a foreign
Person to do business, and is in good standing, in each jurisdiction where the
character of its owned or leased properties or the nature of its activities
makes such qualification necessary, except where the failure to be so qualified
or in good standing would not, individually or in the aggregate, have a SEQUUS
Material Adverse Effect. For the purposes of this Agreement, "SEQUUS Material
Adverse Effect" means any change, event or effect that is materially adverse to
the business, prospects (as they relate to Doxil), financial condition or
results of operations of SEQUUS and its Subsidiaries taken as a whole;
 
                                      A-6
<PAGE>
 
provided, however, that: (i) any adverse change, event or effect arising from
or relating to general business or economic conditions which does not affect
SEQUUS in a materially disproportionate manner, shall not be deemed to
constitute, and shall not be taken into account in determining whether there
has been, a "SEQUUS Material Adverse Effect"; (ii) any adverse change, event or
effect relating to or affecting the oncological pharmaceuticals industry
generally, or relating to or affecting the sale, marketing or development of
oncological pharmaceuticals generally, which does not affect SEQUUS in a
materially disproportionate manner, shall not be deemed to constitute, and
shall not be taken into account in determining whether there has been, a
"SEQUUS Material Adverse Effect"; (iii) any adverse change, event or effect
referred to in Section 3.1 of the SEQUUS Disclosure Statement concerning the
competitive products identified therein shall not be deemed to constitute, and
shall not be taken into account in determining whether there has been, a
"SEQUUS Material Adverse Effect"; and (iv) any adverse change, event or effect
arising from or relating to the announcement or pendency of the Merger shall
not be deemed to constitute, and shall not be taken into account in determining
whether there has been, a "SEQUUS Material Adverse Effect"; provided, further,
that the failure of SEQUUS to meet the published estimates, expectations or
projections of financial analysts shall not by itself constitute a "SEQUUS
Material Adverse Effect".
 
(b) Neither SEQUUS nor any of its Subsidiaries is in violation of any provision
of its certificate of incorporation, bylaws or any other charter document.
Section 3.1 of the SEQUUS Disclosure Statement sets forth (i) the full name of
each Subsidiary of SEQUUS, its capitalization and the ownership interest of
SEQUUS and each other Person (if any) therein, (ii) the jurisdiction in which
each such Subsidiary is organized, (iii) each jurisdiction in which SEQUUS and
each Subsidiary of SEQUUS is qualified to do business as a foreign Person, (iv)
a brief summary of the business and material operations of each Subsidiary of
SEQUUS, and (v) the names of the current directors and officers of SEQUUS and
of each Subsidiary of SEQUUS. SEQUUS has made available to ALZA accurate and
complete copies of the certificate of incorporation, bylaws and any other
charter documents, as currently in effect, of SEQUUS and each of its
Subsidiaries.
 
3.2 Authority Relative to this Agreement. SEQUUS has full corporate power and
authority to (i) execute and deliver this Agreement, and (ii) assuming the
approval of the Merger by a majority of the outstanding shares of SEQUUS Common
Stock at the SEQUUS Special Meeting or any adjournment or postponement thereof
in accordance with Delaware Law, consummate the Merger and the other
transactions contemplated hereby. The execution and delivery of this Agreement
by SEQUUS and the consummation by SEQUUS of the Merger and the other
transactions contemplated hereby, have been duly and validly authorized by the
unanimous vote of the board of directors of SEQUUS, and no other corporate
proceedings on the part of SEQUUS are necessary to authorize this Agreement or
to consummate the Merger and the other transactions contemplated hereby (other
than the approval of the Merger by a majority of the outstanding shares of
SEQUUS Common Stock at the SEQUUS Special Meeting or any adjournment or
postponement thereof in accordance with the Delaware Law). This Agreement has
been duly and validly executed and delivered by SEQUUS and, assuming due
authorization, execution and delivery by ALZA and by Merger Sub, constitutes a
valid and binding agreement of SEQUUS, enforceable against SEQUUS in accordance
with its terms, except to the extent that its enforceability may be limited by
applicable bankruptcy, insolvency, reorganization, moratorium or other laws
affecting the enforcement of creditors' rights generally or by general
equitable principles.
 
                                      A-7
<PAGE>
 
3.3 No Violations, Etc. No filing with or notification to, and no permit,
authorization, consent or approval of, any court, administrative agency,
commission, or other governmental or regulatory body, authority or
instrumentality ("Government Entity") is necessary to be made or obtained on
the part of SEQUUS for the consummation by SEQUUS of the Merger and the other
transactions contemplated hereby, or (assuming, for this purpose, that no laws
are applicable to ALZA that are not also applicable to SEQUUS) for the exercise
by ALZA and the Surviving Corporation of full rights to own and operate the
business of SEQUUS and its Subsidiaries as presently being conducted, except
(i) for the filing of the Certificate of Merger as required by Delaware Law,
(ii) as may be required under the applicable requirements of the Securities and
Exchange Act of 1934, as amended (together with the Rules and Regulations
promulgated thereunder, the "Exchange Act"), state securities or "blue sky"
laws and state takeover laws, and (iii) for any filing required under the Hart-
Scott-Rodino Antitrust Improvements Act of 1976 (the "HSR Act") or any
antitrust laws of any foreign country. Neither the execution and delivery by
SEQUUS of this Agreement, nor the consummation of the Merger by SEQUUS and the
other transactions contemplated hereby, nor compliance by SEQUUS with all of
the provisions hereof, nor the exercise by ALZA and the Surviving Corporation
of full rights to own and operate the business of SEQUUS and its Subsidiaries
as presently being conducted (assuming, for this purpose, that no laws are
applicable to ALZA that are not also applicable to SEQUUS) will, subject to
obtaining the approval of this Agreement by the holders of a majority of the
outstanding shares of SEQUUS Common Stock at the SEQUUS Special Meeting or any
adjournment or postponement thereof in accordance with Delaware Law, (i)
conflict with or result in any breach of any provision of the certificate of
incorporation, bylaws or other charter document of SEQUUS or any of its
Subsidiaries, (ii) violate any material order, writ, injunction, decree,
statute, rule or regulation applicable to SEQUUS or any of its Subsidiaries, or
by which any of their properties or assets is bound, or (iii) result in a
violation or breach of, or constitute (with or without due notice or lapse of
time or both) a default under, or result in any material adverse change in, or
give rise to any right of termination, cancellation, acceleration, redemption
or repurchase under, any of the terms, conditions or provisions of any material
note, bond, mortgage, indenture, deed of trust, license, lease, contract,
agreement or other instrument or obligation to which SEQUUS or any of its
Subsidiaries is a party or by which any of them or any of their properties or
assets may be bound. Section 3.3 of the SEQUUS Disclosure Statement lists all
consents, waivers and approvals required to be obtained other than by ALZA or
any ALZA Subsidiary in connection with the consummation by SEQUUS of the
transactions contemplated hereby under any of SEQUUS' or any of its
Subsidiaries' notes, bonds, mortgages, indentures, deeds of trust, licenses,
leases, contracts, agreements or other instruments or obligations the failure
to obtain which would have a SEQUUS Material Adverse Effect.
 
3.4 Board Recommendation. The board of directors of SEQUUS has, at a meeting of
such board duly held on October 4, 1998, (i) approved this Agreement, (ii)
determined that this Agreement is fair to and in the best interests of the
stockholders of SEQUUS, (iii) resolved to recommend approval of this Agreement
to the stockholders of SEQUUS, (iv) resolved that SEQUUS take all action
necessary to exempt the execution and delivery of this Agreement and the
consummation of the transactions contemplated hereby and thereby from the
provisions of all applicable state antitakeover statutes or regulations
including but not limited to Section 203 of the Delaware Law, and (v) resolved
to render the rights issued under the SEQUUS Rights Plan inapplicable to the
Merger, this Agreement, and the other transactions contemplated hereby.
 
                                      A-8
<PAGE>
 
3.5 Fairness Opinion. SEQUUS has received the opinion of Credit Suisse First
Boston dated the date of the approval of this Agreement by the board of
directors of SEQUUS to the effect that the Exchange Ratio is fair to SEQUUS'
stockholders from a financial point of view, and will provide a copy of such
opinion to ALZA.
 
3.6 Capitalization.
 
(a) The authorized capital stock of SEQUUS consists of 45,000,000 shares of
SEQUUS Common Stock and 4,000,000 shares of Preferred Stock, $.01 par value
("SEQUUS Preferred Stock"), of which 450,000 shares have been designated Series
A Preferred Stock. As of September 30, 1998, there were (i) 31,772,902 shares
of SEQUUS Common Stock outstanding, (ii) no shares of SEQUUS Preferred Stock
outstanding, and (iii) no treasury shares held by SEQUUS.
 
(b) Except as referred to in Section 3.6(a) hereof, and except for securities
issued or outstanding or reserved for issuance under the SEQUUS Stock Plans,
SEQUUS Purchase Plan, SEQUUS Rights Plan and the warrants dated May 19, 1995,
as of September 30, 1998 there were no equity securities of any class of
SEQUUS, or any securities convertible into or exercisable for any such equity
securities, issued, reserved for issuance or outstanding. Except for options
granted under the SEQUUS Stock Plans, purchase rights under the SEQUUS Purchase
Plan, SEQUUS Rights and the warrants dated May 19, 1995, there are no warrants,
options, convertible securities, calls, rights, stock appreciation rights,
preemptive rights, rights of first refusal, or agreements or commitments of any
nature obligating SEQUUS to issue, deliver or sell, or cause to be issued,
delivered or sold, additional shares of capital stock or other equity interests
of SEQUUS, or obligating SEQUUS to grant, issue, extend, accelerate the vesting
of, or enter into, any such warrant, option, convertible security, call, right,
stock appreciation right, preemptive right, right of first refusal, agreement
or commitment. To the knowledge of SEQUUS as of the date of this Agreement,
except for the Voting Agreements entered into as of the date of this agreement
by the members of the board of directors of SEQUUS (the "Voting Agreements"),
there are no voting trusts, proxies or other similar agreements or
understandings with respect to the capital stock of SEQUUS.
 
(c) True and complete copies of each SEQUUS Stock Plan and the SEQUUS Purchase
Plan, and of the forms of all agreements and instruments relating to or issued
under each thereof, have been made available to ALZA. Such agreements,
instruments and forms have not been amended, modified or supplemented in any
significant respect, and there are no agreements to amend, modify or supplement
in any significant respect any such agreements, instruments or forms.
 
(d) Section 3.6 of the SEQUUS Disclosure Statement sets forth the following
information with respect to each option to purchase SEQUUS Common Stock
outstanding as of the date of this Agreement: the aggregate number of shares
issuable thereunder, the type of option, the grant date, the expiration date
and the exercise price. Each SEQUUS Option was or will be granted in accordance
with the terms of the SEQUUS Stock Plan applicable thereto. The terms of each
of the SEQUUS Stock Plans do not prohibit the assumption of the SEQUUS Options
as provided in Section 2.2(a). Consummation of the Merger will not accelerate
vesting of any options to purchase SEQUUS Common Stock outstanding as of the
date of this Agreement, except as described in Section 3.6 of the SEQUUS
Disclosure Statement.
 
                                      A-9
<PAGE>
 
3.7 SEC Filings.
 
(a) SEQUUS has filed with the Securities and Exchange Commission (the "SEC")
all required forms, reports, registration statements and documents required to
be filed by it with the SEC (collectively, all such forms, reports,
registration statements and documents filed since January 1, 1995 are referred
to herein as the "SEQUUS SEC Reports"). All of the SEQUUS SEC Reports complied
as to form, when filed, in all material respects with the applicable provisions
of the Securities Act of 1933, as amended (together with the rules and
regulations promulgated thereunder, the "Securities Act") and the Exchange Act.
Accurate and complete copies of the SEQUUS SEC Reports have been made available
to ALZA. As of their respective dates, the SEQUUS SEC Reports (when taken
together with the documents incorporated by reference therein and all exhibits
and schedules thereto) did not contain any untrue statement of a material fact
or omit to state a material fact required to be stated therein or necessary to
make the statements therein, in light of the circumstances under which they
were made, not misleading. SEQUUS has been advised by each of its executive
officers and directors that each such person and such persons' affiliates have
complied with all filing requirements relating to SEQUUS under Section 13 and
Section 16(a) of the Exchange Act except as disclosed in the SEQUUS SEC
Reports.
 
3.8 Financial Statements. Each of the consolidated financial statements
(including, in each case, any related notes thereto) contained in the SEQUUS
SEC Reports (the "SEQUUS Financial Statements"), (x) was prepared in accordance
with generally accepted accounting principles ("GAAP") applied on a consistent
basis throughout the periods involved (except as may be indicated in the notes
thereto or, in the case of unaudited interim financial statements, as may be
permitted by the SEC on Form 10-Q under the Exchange Act) and (y) fairly
presented the financial position of SEQUUS as at the respective dates thereof
and the results of its operations and cash flows for the periods indicated,
consistent with the books and records of SEQUUS, except that the unaudited
interim financial statements were or are subject to normal and recurring year-
end adjustments which, in the case of the interim financial statements
contained in SEQUUS' Form 10-Q for the quarter ended June 30, 1998, are not
expected to be material in amount. The balance sheet of SEQUUS contained in
SEQUUS' Form 10-Q for the quarter ended June 30, 1998 (the "Reference Date") is
hereinafter referred to as the "SEQUUS Balance Sheet."
 
3.9 Absence of Undisclosed Liabilities. Neither SEQUUS nor any of its
Subsidiaries has any liabilities (absolute, accrued, contingent or otherwise)
other than (i) liabilities included in the SEQUUS Balance Sheet and the related
notes to the financial statements, (ii) normal or recurring liabilities
incurred since the Reference Date in the ordinary course of business consistent
with past practice which, individually or in the aggregate, would not be
reasonably likely to have a SEQUUS Material Adverse Effect, and (iii)
liabilities under this Agreement.
 
3.10 Absence of Changes or Events. Except as contemplated by this Agreement,
since the Reference Date, no SEQUUS Material Adverse Effect has occurred. In
addition, between the Reference Date and the date of this Agreement, SEQUUS and
its Subsidiaries have not, directly or indirectly:
 
(a) purchased, otherwise acquired, or agreed to purchase or otherwise acquire,
any shares of capital stock of SEQUUS or any of its Subsidiaries, or declared,
set aside or paid any dividend or otherwise
 
                                      A-10
<PAGE>
 
made a distribution (whether in cash, stock or property or any combination
thereof) in respect of their capital stock (other than dividends or other
distributions payable solely to SEQUUS or a wholly owned Subsidiary of SEQUUS
or repurchases of unvested shares from employees in connection with the
termination of employment (for any reason) in accordance with agreements
outstanding or policies existing on the date hereof, or entered into thereafter
in the ordinary course of business);
 
(b) (i) created or incurred any indebtedness for borrowed money exceeding
$250,000 in the aggregate, or (ii) assumed, guaranteed, endorsed or otherwise
as an accommodation become responsible for the obligations of any other
individual, firm or corporation, made any loans or advances to any other
individual, firm or corporation exceeding $100,000 in the aggregate except for
travel advances and other advances made to employees in the ordinary course of
business;
 
(c) instituted any change in accounting methods, principles or practices other
than as required by GAAP or the rules and regulations promulgated by the SEC
and disclosed in the notes to the SEQUUS Financial Statements;
 
(d) revalued any assets, including, without limitation, writing down the value
of inventory or writing off notes or accounts receivable in excess of amounts
previously reserved as reflected in the SEQUUS Balance Sheet;
 
(e) suffered any damage, destruction or loss, whether covered by insurance or
not, except for such as would not, individually and in the aggregate exceed
$250,000;
 
(f) (i) increased in any manner the compensation of any of its directors,
officers (including specifically that in the aggregate bonuses payable to its
officers with respect to 1998 will not exceed 30% of the aggregate salaries of
such officers for 1998) or, other than in the ordinary course of business and
consistent with past practice or pursuant to written agreements outstanding on
the date hereof, non-officer employees; (ii) granted any severance or
termination pay to any Person; (iii) entered into any oral or written
employment, consulting, indemnification or severance agreement with any Person
other than agreements involving amounts in each case not in excess of $75,000;
(iv) other than as required by law or the specific terms of its Employee
Benefit Plans, adopted, become obligated under, or amended any employee benefit
plan, program or arrangement; or (v) repriced any SEQUUS options granted under
the SEQUUS Stock Plans;
 
(g) sold, transferred, leased to a third party, licensed to a third party,
pledged, mortgaged, encumbered, or otherwise disposed of, or agreed to sell,
transfer, lease to a third party, license to a third party, pledge, mortgage,
encumber or otherwise dispose of, any material portion of any material
properties (including intangibles, real, personal or mixed);
 
(h) amended its certificate of incorporation, bylaws or any other charter
document, or effected or been a party to any Merger, consolidation, share
exchange, business combination, recapitalization, reclassification of shares,
stock split, reverse stock split or similar transaction;
 
(i) made any capital expenditure in any calendar month which, when added to all
other capital expenditures made by or on behalf of SEQUUS and its Subsidiaries
in such calendar month resulted in such capital expenditures exceeding $250,000
in the aggregate;
 
(j) paid, discharged or satisfied any material claims, liabilities or
obligations (absolute, accrued, contingent or otherwise), other than the
payment, discharge or satisfaction of liquidated claims,
 
                                      A-11
<PAGE>
 
liabilities or obligations when due and the payment, discharge or satisfaction
of liabilities (including accounts payable) in the ordinary course of business
and consistent with past practice, or collected, or accelerated the collection
of, any material amounts owed (including accounts receivable) other than their
collection in the ordinary course of business;
 
(k) waived, released, assigned, settled or compromised any material claim or
litigation, or commenced a lawsuit other than in the ordinary course of
business for the routine collection of bills; or
 
(l) offered or become obligated to do any of the things described in the
preceding clauses (a) through (k) other than as expressly contemplated or
provided for in this Agreement.
 
3.11 Intentionally Omitted.
 
3.12 Litigation.
 
(a) There is no private or governmental action or suit (whether in law or in
equity), or governmental investigation or proceeding of any nature ("Action")
pending or, to the knowledge of SEQUUS, threatened against SEQUUS or any of
its Subsidiaries, or any of their respective officers and directors (in their
capacities as such), or involving any of their assets, before any court,
governmental or regulatory authority or body, or arbitration tribunal, except
for those Actions which, individually and in the aggregate, would not have a
SEQUUS Material Adverse Effect. As of the date of this Agreement, there is no
Action pending or, to the knowledge of SEQUUS, threatened which in any manner
challenges seeks to, or is reasonably likely to prevent, enjoin, alter or
delay the transactions contemplated by this Agreement.
 
(b) There is no outstanding unsatisfied judgment, order, writ, injunction or
decree of any court, governmental or regulatory authority or body, or
arbitration tribunal in a proceeding to which SEQUUS, any Subsidiary of
SEQUUS, or any of their assets is or was a party or by which SEQUUS, any
Subsidiary of SEQUUS, or any of their assets is bound.
 
3.13 Insurance. Section 3.13 of the SEQUUS Disclosure Statement lists all
insurance policies in effect as of the date of this Agreement (including
without limitation workers' compensation insurance policies) covering the
business, properties or assets of SEQUUS and its Subsidiaries, the premiums
and coverages of such policies, and all claims in excess of $50,000 made
against any such policies since January 1, 1995. All such policies are in
effect, and true and complete copies of all such policies have been made
available to ALZA. SEQUUS has not received notice of the cancellation or
threat of cancellation of any of such policies.
 
3.14 Contracts and Commitments.
 
(a) As of the date of this Agreement, except as filed as an exhibit to the
SEQUUS SEC Reports, neither SEQUUS nor its Subsidiaries is a party to or bound
by any oral or written contract, obligation or commitment of any type in any
of the following categories:
 
  (i) employment agreements, consulting agreements, agreements or
  arrangements that contain severance pay, employee or consultant
  indemnification employment liabilities or obligations; agreements,
  agreements or understandings with respect to tax arrangements,
 
                                     A-12
<PAGE>
 
  agreements or understandings with respect to expatriate benefits, or
  post-employment liabilities or obligations;
 
  (ii) agreements or plans under which benefits will be increased or
  accelerated by the occurrence of any of the transactions contemplated
  by this Agreement, or under which the value of the benefits will be
  calculated on the basis of any of the transactions contemplated by this
  Agreement;
 
  (iii) agreements, contracts or commitments currently in force relating
  to the disposition or acquisition of (i) material assets other than in
  the ordinary course of business, or (ii) relating to an ownership
  interest in any corporation, partnership, joint venture or other
  business enterprise;
 
  (iv) material agreements, contracts or commitments for the purchase of
  materials, supplies or equipment which provide for purchase prices
  substantially greater than those prevailing as of the date of this
  Agreement for such materials, supplies or equipment, or which are with
  sole or single source suppliers;
 
  (v) guarantees or other agreements, contracts or commitments under
  which SEQUUS or any of its Subsidiaries is absolutely or contingently
  liable for (A) the performance of any other person, firm or corporation
  (other than SEQUUS or its Subsidiaries), or (B) the whole or any part
  of the indebtedness or liabilities of any other person, firm or
  corporation (other than SEQUUS or its Subsidiaries);
 
  (vi) powers of attorney authorizing the incurrence of a material
  obligation on the part of SEQUUS or its Subsidiaries;
 
  (vii) agreements, contracts or commitments which limit or restrict (A)
  the geographic territories where SEQUUS or any of its Subsidiaries may
  conduct business, (B) the type or lines of business (current or future)
  in which they may engage, or (C) any acquisition of assets (tangible or
  intangible) by SEQUUS or any of its Subsidiaries outside of the
  ordinary course of business;
 
  (viii) agreements, contracts or commitments containing any agreement
  with respect to a change of control of SEQUUS or any of its
  Subsidiaries;
 
  (ix) agreements, contracts or commitments for the borrowing or lending
  of money, or the availability of credit (except credit extended by
  SEQUUS or any of its Subsidiaries to customers in the ordinary course
  of business and consistent with past practice);
 
  (x) any hedging, option, derivative or other similar transaction and
  any foreign exchange position or contract for the exchange of currency;
 
  (xi) any joint marketing or joint development agreement, or any license
  or distribution agreement relating to any SEQUUS product not cancelable
  by SEQUUS upon 90 days notice; or
 
  (xii) any agreement not otherwise disclosed in section 3.14 or 3.17 of
  the SEQUUS Disclosure Statement expressly obligating SEQUUS to
  indemnify any other Person, including but not limited to any employee
  or consultant of SEQUUS or any of its Subsidiaries, against any charge
  of infringement, misappropriation or misuse of any
 
                                      A-13
<PAGE>
 
  intellectual property, other than indemnification provisions contained
  in purchase orders or customer agreements arising in the ordinary
  course of business.
 
(b) Neither SEQUUS nor any of its Subsidiaries, nor to SEQUUS' knowledge any
other party to a SEQUUS Contract (as defined below), is in breach, violation or
default under, or has received notice that it has breached, violated or
defaulted under (nor does there exist any condition under which, with the
passage of time or the giving of notice or both, could reasonably be expected
to cause such a breach, violation or default under), any material agreement,
contract or commitment to which SEQUUS or any of its Subsidiaries is a party or
by which any of them or any of their properties or assets is bound (any such
agreement, contract or commitment, a "SEQUUS Contract"), other than any
breaches, violations or defaults which individually or in the aggregate would
not have a SEQUUS Material Adverse Effect.
 
(c) Each SEQUUS Contract is a valid, binding and enforceable obligation of
SEQUUS and, to SEQUUS' knowledge, of the other party or parties thereto, in
accordance with its terms, and in full force and effect, except where the
failure to be valid, binding, enforceable and in full force and effect would
not have a SEQUUS Material Adverse Effect and to the extent enforcement may be
limited by applicable bankruptcy, insolvency, moratorium or other laws
affecting the enforcement of creditors' rights generally or by general
principles of equity or by competition laws of the European Union.
 
(d) An accurate and complete copy of each SEQUUS Contract has been made
available to ALZA.
 
3.15 Labor Matters; Employment and Labor Contracts.
 
(a) None of SEQUUS or any of its Subsidiaries is a party to any union contract
or other collective bargaining agreement, nor to the knowledge of SEQUUS or any
of its Subsidiaries are there any activities or proceedings of any labor union
to organize any of its employees. Each of SEQUUS and its Subsidiaries is in
compliance with all applicable (i) laws, regulations and agreements respecting
employment and employment practices, (ii) terms and conditions of employment,
and (iii) occupational health and safety requirements, except for those
failures to comply which, individually or in the aggregate, would not have a
SEQUUS Material Adverse Effect.
 
(b) There is no labor strike, slowdown or stoppage pending (or any labor strike
or stoppage threatened) against SEQUUS or any of its Subsidiaries. No petition
for certification has been filed and is pending before the National Labor
Relations Board with respect to any employees of SEQUUS or any of its
Subsidiaries who are not currently organized. Neither SEQUUS nor any of its
Subsidiaries has any obligations under the Consolidated Omnibus Budget
Reconciliation Act of 1985, as amended ("COBRA"), with respect to any former
employees or qualifying beneficiaries thereunder, except for obligations that
would not have, individually or in the aggregate, a SEQUUS Material Adverse
Effect. There are no actions, complaints or investigations pending or, to the
knowledge of SEQUUS or any of its Subsidiaries, threatened, between SEQUUS or
any of its Subsidiaries and any of their respective employees.
 
3.16 Compliance with Laws. (a) Neither SEQUUS nor any of its Subsidiaries has
violated or failed to comply with any statute, law, ordinance, rule or
regulation (including without limitation relating to the export or import of
goods or technology) of any foreign, federal, state or local government or any
other governmental department or agency, except where any such violations or
 
                                      A-14
<PAGE>
 
failures to comply would not, individually or in the aggregate, have a SEQUUS
Material Adverse Effect. SEQUUS and its Subsidiaries have all permits, licenses
and franchises from governmental agencies required to conduct their businesses
as now being conducted and SEQUUS has no knowledge of any reason that SEQUUS
will not be able to obtain the permits, licenses and franchises from any
governmental agency required to conduct its business as proposed to be
conducted, except for those, the absence of which, would not, individually or
in the aggregate, have a SEQUUS Material Adverse Effect.
 
(b) To SEQUUS' knowledge, as to each product subject to United States Food and
Drug Administration (the "FDA") jurisdiction under the Federal Food, Drug and
Cosmetic Act ("FDCA") and the jurisdiction of the Drug Enforcement Agency
("DEA") under the Comprehensive Drug Abuse Prevention and Control Act of 1970
("CSA") that is manufactured, tested, distributed, held, and/or marketed by
SEQUUS or any Subsidiary, such product is being manufactured, held, distributed
and marketed in substantial compliance with all applicable requirements under
the FDCA and the CSA including, but not limited to, those relating to
investigational use, premarket clearance, good manufacturing practices,
labeling, advertising, record keeping, filing of reports and security.
 
(c) SEQUUS has, prior to the execution of this Agreement, provided to ALZA
copies of or made available for ALZA's review any and all documents in its or
any Subsidiary's possession material to assessing SEQUUS' or any SEQUUS
Subsidiary's compliance with the FDCA or the CSA and implementing regulations,
including, but not limited to, copies in its possession of (i) all 483s issued
during the last three years; (ii) all audit reports performed during the last
three years, whether performed by SEQUUS, any SEQUUS Subsidiary, or an outside
consultant; (iii) any document (prepared by SEQUUS or otherwise) concerning any
material oral or written communication received from the FDA, the DEA, or the
Department of Justice during the last three years; (iv) any administrative or
judicial order, ruling or agreement issued or entered into during the last
three years in which SEQUUS, any Subsidiary of SEQUUS, or their respective
predecessor companies were a named party or were identified as an interested
person; or (v) any recall notice or order relating to any product of SEQUUS.
 
3.17 Intellectual Property Rights.
 
(a) SEQUUS and its Subsidiaries own or have the right to use all intellectual
property material to the conduct of their respective businesses (such
intellectual property and such rights are collectively referred to herein as
the "SEQUUS IP Rights"). No royalties or other payments relating to the use of
intellectual property rights are payable by SEQUUS, or to its knowledge, its
licensees or distributors, to any Person with respect to commercialization of
any products presently sold or under development by SEQUUS or its Subsidiaries.
 
(b) The execution, delivery and performance of this Agreement by SEQUUS and the
consummation by SEQUUS of the transactions contemplated hereby will not (i)
constitute a material breach by SEQUUS or any of its Subsidiaries of any
instrument or agreement governing any SEQUUS IP Rights, (ii) cause the
modification of any terms of any licenses or agreements relating to any SEQUUS
IP Rights including but not limited to the modification of the effective rate
of any royalties or other payments provided for in any such license or
agreement, (iii) cause the forfeiture or
 
                                      A-15
<PAGE>
 
termination of any SEQUUS IP Rights, (iv) give rise to a right of forfeiture or
termination of any SEQUUS IP Rights or (v) materially impair the right of
SEQUUS (subject to Section 5.1 of this Agreement), the Surviving Corporation or
ALZA to use, sell or license any SEQUUS IP Rights or portion thereof.
 
(c) Neither the manufacture, marketing, license, sale or intended use (as set
forth in Section 3.17(c) of the SEQUUS Disclosure Statement) of any Material
Product by SEQUUS, nor the current use by SEQUUS of the Stealth Platform
Technology, (i) violates in any material respect any license or agreement
between SEQUUS or any of its Subsidiaries and any third party or (ii) infringes
in any material respect any patents or other intellectual property rights of
any other party; and there is no pending or threatened claim or litigation
contesting the validity, ownership or right to use, sell, license or dispose of
any SEQUUS IP Rights, or asserting that any SEQUUS IP Rights or the proposed
use, sale, license or disposition thereof, or the manufacture, use or sale of
any SEQUUS products, conflicts or will conflict with the rights of any other
party.
 
(d) SEQUUS has heretofore provided to ALZA a worldwide list of all patents,
trade names, registered trademarks and registered service marks, and
applications for any of the foregoing, owned or possessed by SEQUUS or any of
its Subsidiaries and true and complete copies of such materials have been made
available to ALZA.
 
(e) SEQUUS has provided to ALZA a true and complete copy of its standard form
of employee confidentiality agreement and taken all commercially reasonably
necessary steps to ensure that all employees have executed such an agreement.
All consultants or third parties with access to proprietary information of
SEQUUS have executed appropriate non-disclosure agreements.
 
(f) Neither SEQUUS nor any of its Subsidiaries is aware or has reason to
believe that any of its employees or consultants is obligated under any
contract, covenant or other agreement or commitment of any nature, or subject
to any judgment, decree or order of any court or administrative agency, that
would interfere with the use of such employee's or consultant's best efforts to
promote the interests of SEQUUS and its Subsidiaries or that would conflict
with the business of SEQUUS as presently conducted or proposed to be conducted.
All current and former employees and consultants of SEQUUS or any of its
Subsidiaries have signed valid and enforceable written assignments to SEQUUS or
its Subsidiaries of any and all rights or claims in any intellectual property
that is used in the business of SEQUUS that any such employee or consultant has
or may have by reason of any contribution, participation or other role in the
development, conception, creation, reduction to practice or authorship of any
invention, innovation, development or work of authorship or any other
intellectual property that is used in the business of SEQUUS, and SEQUUS and
its Subsidiaries possess signed copies of all such written assignments by such
employees and consultants.
 
3.18 Taxes.
 
(a) For the purposes of this Agreement, "Tax" or "Taxes" refers to any and all
federal, state, local and foreign taxes, assessments and other governmental
charges, duties, impositions and liabilities relating to taxes, including taxes
based upon or measured by gross receipts, income, profits, sales, use and
occupation, and value added, ad valorem, transfer, franchise, withholding,
payroll, recapture, employment, excise and property taxes, together with all
interest, penalties and additions imposed with respect to such amounts and any
obligations under any agreements or arrangements with any
 
                                      A-16
<PAGE>
 
other person with respect to such amounts and including any liability for taxes
of a predecessor entity. For purposes of this Agreement, "Tax Return" or "Tax
Returns" refers to all federal, state and local and foreign returns, estimates,
information statements and reports relating to Taxes.
 
(b) SEQUUS and each of its Subsidiaries have filed all material Tax Returns
required to be filed by them, and have paid (or SEQUUS has paid on behalf of
its Subsidiaries), or have set up adequate reserves (which reserves were
established in accordance with GAAP) for the payment of, all Taxes required to
be paid as shown on such Tax Returns. The most recent financial statements
contained in the SEQUUS SEC Reports reflect an adequate reserve (which reserves
were established in accordance with GAAP) for the payment of all Taxes payable
by SEQUUS and its Subsidiaries, accrued through the date of such financial
statements. Except as would not reasonably be expected to have a SEQUUS
Material Adverse Effect, no deficiencies for any Taxes have been proposed,
asserted or assessed against SEQUUS or any of its Subsidiaries.
 
(c) There is no contract, agreement, plan or arrangement, including but not
limited to the provisions of this Agreement, covering any employee or former
employee of SEQUUS or any of its Subsidiaries that, individually or
collectively, could give rise to the payment of any amount that would not be
deductible pursuant to Sections 280G, 404 or 162 of the Code.
 
(d) None of SEQUUS and its Subsidiaries has filed any consent agreement under
Section 341(f) of the Code or agreed to have Section 341(f)(2) of the Code
apply to any disposition of a subsection (f) asset (as defined in Section
341(f)(4) of the Code) owned by SEQUUS.
 
(e) None of SEQUUS and its Subsidiaries (i) is being audited by any taxing
authority; (ii) has granted any presently operative waiver of any statute of
limitations with respect to, or any extension of a period for the assessment
of, any Tax; (iii) has permitted any Tax lien to be placed on any asset of
SEQUUS or any of its Subsidiaries other than liens for Taxes not yet due and
payable; and (iv) has availed itself of any Tax amnesty or similar relief in
any taxing jurisdiction.
 
(f) None of SEQUUS and its Subsidiaries is aware of any reason why the Merger
will fail to qualify as a reorganization under the provisions of Section 368(a)
of the Code.
 
3.19 Employee Benefit Plans; ERISA.
 
(a) Section 3.19(a) of the SEQUUS Disclosure Statement lists all "employee
pension benefit plans" as defined in Section 3(2) of the Employee Retirement
Income Security Act of 1974, as amended ("ERISA") ("Pension Plans"), "welfare
benefit plans" as defined in Section 3(1) of ERISA ("Welfare Plans"), or stock
bonus, stock option, restricted stock, stock appreciation right, stock
purchase, bonus, incentive, deferred compensation, severance, holiday, or
vacation plans, or any other employee benefit plan, program, policy or
arrangement covering employees (or former employees) of SEQUUS employed in the
United States that either is maintained or contributed to by SEQUUS or any of
its Subsidiaries or any of their ERISA Affiliates (as hereinafter defined) or
to which SEQUUS or any of its Subsidiaries or any of their ERISA Affiliates is
obligated to make payments or otherwise may have any liability (collectively,
the "Employee Benefit Plans") with respect to employees or former employees of
SEQUUS, its Subsidiaries, or any of their ERISA Affiliates. For purposes of
this Agreement, "ERISA Affiliate" shall mean any person (as defined in Section
3(9) of ERISA) that is or has been a member of any group of persons described
in Section 414(b), (c), (m) or (o) of the Code, including without limitation
SEQUUS or a Subsidiary.
 
                                      A-17
<PAGE>
 
(b) SEQUUS and each of its Subsidiaries, and each of the Pension Plans and
Welfare Plans, are in compliance with the applicable provisions of ERISA, the
Code and other applicable laws, except where the failure to comply would not,
individually or in the aggregate, have a SEQUUS Material Adverse Effect.
 
(c) All contributions to, and payments from, the Pension Plans which are
required to have been made in accordance with the Pension Plans have been
timely made, except where the failure to make such contributions or payments on
a timely basis would not, individually or in the aggregate, either impair
SEQUUS' ability to consummate the Merger and the other transactions
contemplated hereby or have a SEQUUS Material Adverse Effect.
 
(d) All of SEQUUS' Pension Plans intended to qualify under Section 401 of the
Code have been determined by the Internal Revenue Service ("IRS") to be so
qualified, and no event has occurred and no condition exists with respect to
the form or operation of such Pension Plans which would cause the loss of such
qualification or the imposition of any material liability, penalty or tax under
ERISA or the Code.
 
(e) There are no (i) investigations pending by any governmental entity
involving the Pension Plans or Welfare Plans, or (ii) pending or threatened
claims (other than routine claims for benefits), suits or proceedings against
any Pension Plan or Welfare Plan, against the assets of any of the trusts under
any Pension Plan or Welfare Plan or against any fiduciary of any Pension Plan
or Welfare Plan with respect to the operation of such plan or asserting any
rights or claims to benefits under any Pension Plan or against the assets of
any trust under such plan, except for those which would not, individually or in
the aggregate, give rise to any liability which would have a SEQUUS Material
Adverse Effect. To the best of SEQUUS' knowledge, there are no facts which
would give rise to any liability under this Section 3.19(e) except for those
which would not, individually or in the aggregate, either impair SEQUUS'
ability to consummate the Merger and the other transactions contemplated hereby
or have a SEQUUS Material Adverse Effect in the event of any such
investigation, claim, suit or proceeding.
 
(f) None of SEQUUS, any of its Subsidiaries or any employee of the foregoing,
or any trustee, administrator, other fiduciary or any other "party in interest"
or "disqualified person" with respect to the Pension Plans or Welfare Plans,
has engaged in a "prohibited transaction" (as such term is defined in Section
4975 of the Code or Section 406 of ERISA) other than such transactions that
would not, individually or in the aggregate, either impair SEQUUS' ability to
consummate the Merger and the other transactions contemplated hereby or have a
SEQUUS Material Adverse Effect.
 
(g) None of SEQUUS, any of its Subsidiaries, or any of their ERISA Affiliates
maintain or contribute to, nor have they ever maintained or contributed to, any
pension plan subject to Title IV of ERISA or Section 412 of the Code or Section
302 of ERISA.
 
(h) Neither SEQUUS nor any Subsidiary of SEQUUS nor any ERISA Affiliate has
incurred any material liability under Title IV of ERISA that has not been
satisfied in full.
 
(i) Neither SEQUUS, any of its Subsidiaries nor any of their ERISA Affiliates
has any material liability (including any contingent liability under Section
4204 of ERISA) with respect to any multiemployer plan, within the meaning of
Section 3(37) of ERISA, covering employees (or former employees) employed in
the United States.
 
                                      A-18
<PAGE>
 
(j) With respect to each of the Employee Benefit Plans, true, correct and
complete copies of the following documents have been made available to ALZA:
(i) the plan document and any related trust agreement, including amendments
thereto, (ii) any current summary plan descriptions and other material
communications to participants relating to the Employee Benefit Plans, (iii)
the three most recent Forms 5500, if applicable, and (iv) the most recent IRS
determination letter, if applicable.
 
(k) None of the Welfare Plans maintained by SEQUUS or any of its Subsidiaries
provides for continuing benefits or coverage for any participant or any
beneficiary of a participant following termination of employment, except as may
be required under COBRA, or except at the expense of the participant or the
participant's beneficiary SEQUUS and each of its Subsidiaries which maintain a
"group health plan" within the meaning of Section 5000(b)(1) of the Code have
complied with the notice and continuation requirements of Section 4980B of the
Code, COBRA, Part 6 of Subtitle B of Title I of ERISA and the regulations
thereunder except where the failure to comply would not, individually or in the
aggregate, either impair SEQUUS' ability to consummate the Merger and the other
transactions contemplated hereby or have a SEQUUS Material Adverse Effect.
 
(l) No liability under any Pension Plan or Welfare Plan has been funded nor has
any such obligation been satisfied with the purchase of a contract from an
insurance company as to which SEQUUS or any of its Subsidiaries has received
notice that such insurance company is in rehabilitation or a comparable
proceeding.
 
(m) The consummation of the transactions contemplated by this Agreement will
not result in an increase in the amount of compensation or benefits or
accelerate the vesting or timing of payment of any benefits or compensation
payable to or in respect of any employee of SEQUUS or any of its Subsidiaries.
 
(n) Section 3.19 of the SEQUUS Disclosure Statement lists each Foreign Plan (as
hereinafter defined). SEQUUS and each of its Subsidiaries and each of the
Foreign Plans are in compliance with applicable laws, and all required
contributions have been made to the Foreign Plans, except where the failure to
comply or make contributions would not, individually or in the aggregate,
either impair SEQUUS' ability to consummate the Merger and the other
transactions contemplated hereby or have a SEQUUS Material Adverse Effect. Each
of the Foreign Plans that is a funded defined benefit pension plan has a fair
market value of plan assets that is greater than the plan's liabilities, as
determined in accordance with applicable laws. For purposes hereof, the term
"Foreign Plan" shall mean any plan, program, policy, arrangement or agreement
maintained or contributed to by, or entered into with, SEQUUS or any Subsidiary
with respect to employees (or former employees) employed outside the United
States to the extent the benefits provided thereunder are not mandated by the
laws of the applicable foreign jurisdiction.
 
(o) Each of the Employee Benefit Plans and the Foreign Plans can be terminated
by SEQUUS within a period of 30 days following the Effective Time in accordance
with the terms of such Plan (and the provisions of ERISA and the Code), without
any additional contribution to such Employee Benefit Plan or Foreign Plan or
the payment of any additional compensation or amount or the additional vesting
or acceleration of any vesting provided under the Employee Benefit Plan or
Foreign Plan.
 
                                      A-19
<PAGE>
 
3.20 Environmental Matters.
 
(a) For purposes of this Agreement:
 
  (i) "Contractor" shall mean any person or entity, including but not limited
  to partners, licensors, and licensees, with which SEQUUS formerly or
  presently has any agreement or arrangement (whether oral or written) under
  which such person or entity has or had physical possession of, and was or
  is obligated to develop, test, process, manufacture or produce, any product
  or substance on behalf of SEQUUS.
 
  (ii) "Environment" shall mean any land including, without limitation,
  surface land and sub-surface strata, seabed or river bed and any water
  (including, without limitation, coastal and inland waters, surface waters
  and ground waters and water in drains and sewers) and air (including,
  without limitation, air within buildings) and other natural or manmade
  structures above or below ground.
 
  (iii) "Environmental Law" means any law or regulation, and any applicable
  judicial or administrative interpretation thereof relating to public and
  workers health and safety, emissions, discharges or releases of Hazardous
  Materials into the Environment or otherwise relating to the manufacture,
  processing, use, treatment, storage, distribution, disposal, transport or
  handling of Hazardous Materials. Environmental Laws include, without
  limitation, the Comprehensive Environmental Response, Compensation and
  Liability Act, as amended ("CERCLA"), the Resource Conservation and
  Recovery Act 42 USC, 6901 et seq., the Hazardous Materials Transportation
  Act 49 USC, 6901 et seq., the Clean Water Act 33, 1251 et seq., the Toxic
  Substances Control Act 15 USC, 2601 et seq., the Clean Air Act 42 USC, 7401
  et seq., the Safe Drinking Water Act 42 USC, 300f et seq., the Atomic
  Energy Act 42 USC, 2201 et seq., and the Federal Food Drug and Cosmetic Act
  21 USC, 301 et seq., and equivalent statutes in countries other than the
  United States of America.
 
  (iv) "Environmental Permit" shall mean any permit, license, consent,
  approval, certificate, qualification, specification, registration and other
  authorization, and the filing of all notifications, reports and
  assessments, required by any federal, state, local or foreign government or
  regulatory entity pursuant to any Environmental Law.
 
  (v) "Hazardous Material" shall mean any pollutant, contaminant, or
  hazardous, toxic, medical, biohazardous, infectious or dangerous waste,
  substance, gas, constituent or material, defined or regulated as such in,
  or for purposes of, any Environmental Law, including, without limitation,
  any asbestos, any petroleum, oil (including crude oil or any fraction
  thereof), any radioactive substance, any polychlorinated biphenyls, any
  toxin, chemical, virus, infectious disease or disease causing agent, and
  any other substance that can give rise to liability under any Environmental
  Law.
 
(b) Except for such cases that, individually or in the aggregate, have not and
would not reasonably be expected to have a SEQUUS Material Adverse Effect:
 
  (i) Each of SEQUUS and its Subsidiaries possesses all Environmental Permits
  required under applicable Environmental Laws to conduct its current
  business and to use and occupy the Real Property for its current business.
  All Environmental Permits are in full force and effect and SEQUUS and each
  of its Subsidiaries are in compliance with the terms and conditions of such
  Environmental Permits.
 
                                      A-20
<PAGE>
 
  (ii) There are no facts or circumstances indicating that any Environmental
  Permits possessed by SEQUUS or any of its Subsidiaries are likely to be
  revoked, suspended, canceled or not renewed, and all appropriate necessary
  action in connection with the renewal or extension of any Environmental
  Permits possessed by SEQUUS or any of its Subsidiaries relating to their
  current business and the Real Property has been taken.
 
  (iii) The execution and delivery by SEQUUS of this Agreement and the
  consummation by SEQUUS of the Merger and other transactions contemplated
  hereby and (assuming, for this purpose, that no law is applicable to ALZA
  that is not also applicable to SEQUUS) the exercise by ALZA and the
  Surviving Corporation of rights to own and operate the business of SEQUUS
  and its Subsidiaries and use and occupy the Real Property and carry on its
  business substantially as presently conducted will not affect the validity
  or require the transfer of any Environmental Permits held by SEQUUS or any
  of its Subsidiaries and will not require any notification, disclosure,
  registration, reporting, filing, investigation or remediation under any
  Environmental Law.
 
  (iv) SEQUUS and each of its Subsidiaries are in compliance with, and within
  the period of all applicable statutes of limitation, have complied with,
  all applicable Environmental Laws with respect to the real property now or
  previously owned, leased or occupied by SEQUUS and its Subsidiaries (the
  "Real Property"), and have not received notice of any liability under any
  Environmental Law.
 
  (v) There is no civil, criminal or administrative action, suit, demand,
  claim, complaint, hearing, notice of violation, investigation, notice or
  demand letter, proceeding or request for information pending or any
  liability (whether actual or contingent) to make good, repair, reinstate or
  clean up any of the Real Property; there is no act, omission, event or
  circumstance giving rise or likely to give rise in the future to any such
  action, suit, demand, claim, complaint, hearing, notice of violation,
  investigation, notice or demand letter, proceeding, or request or any such
  liability or other liabilities.
 
  (vi) There has not been any disposal, spill, discharge, or release of any
  Hazardous Material generated, used, owned, stored, or controlled by SEQUUS,
  any of its Subsidiaries, or respective predecessors in interest, on, at, or
  under any property presently or formerly owned, leased, or operated by
  SEQUUS, its Subsidiaries, any predecessor in interest, or any Contractor,
  and there are no Hazardous Materials located in, at, on, or under, or in
  the vicinity of, any such facility or property, or at any other location,
  in either case that could reasonably be expected to require investigation,
  removal, remedial, or corrective action by SEQUUS or any of its
  Subsidiaries or that would reasonably likely result in liability of, or
  costs in excess of, $250,000, individually or in the aggregate, to SEQUUS
  or any of its Subsidiaries under any Environmental Law.
 
  (vii) (A) Other than cleaning and office supplies normally used in the
  operation of an office, Hazardous Materials are not currently generated,
  used, treated, handled or stored on, or transported to or from, or released
  on any Real Property that is currently used or occupied by SEQUUS or any
  property adjoining any Real Property that is currently used or occupied by
  SEQUUS; and (B) neither SEQUUS nor any of its Subsidiaries has transported
  or arranged for the transportation of any Hazardous materials to any
  location that is listed or proposed for listing on the National Priorities
  List under CERCLA or on the CERCLIS or any analogous state or country list
  or which is the subject of any environmental claim.
 
                                      A-21
<PAGE>
 
  (viii) There has not been any underground or aboveground storage tank or
  other underground storage receptacle or related piping, or any impoundment
  or other disposal area containing Hazardous Materials located on any Real
  Property owned, leased or operated by SEQUUS, any of its Subsidiaries, or
  respective predecessors in interest during the period of such ownership,
  lease or operation.
 
  (ix) SEQUUS and its Subsidiaries have taken all actions necessary under
  applicable requirements of Environmental Law to register any products or
  materials required to be registered by SEQUUS or any of its Subsidiaries
  (or any of their respective agents) thereunder.
 
3.21 Officer's Certificate as to Tax Matters. SEQUUS knows of no reason why it
will be unable to deliver to Heller Ehrman White & McAuliffe and Cooley Godward
LLP at the Closing an officer's certificate in form sufficient to enable each
such counsel to render the opinions required by Section 6.5.
 
3.22 Affiliates. The list that SEQUUS will deliver to ALZA in accordance with
Section 5.11(a) will identify all persons who to SEQUUS' knowledge may be
deemed to be "affiliates" of SEQUUS for purposes of Rule 145 under the
Securities Act or under applicable SEC accounting releases with respect to
pooling of interests accounting ("Affiliates").
 
3.23 Finders or Brokers. Except for Credit Suisse First Boston, whose fees have
been disclosed to ALZA, neither SEQUUS nor any of its Subsidiaries has employed
any investment banker, broker, finder or intermediary in connection with the
transactions contemplated hereby who might be entitled to a fee or any
commission the receipt of which is conditioned upon consummation of the Merger.
 
3.24 Registration Statement; Proxy Statement/Prospectus. The information
supplied by SEQUUS for inclusion or incorporation by reference in the
Registration Statement on Form S-4 registering the ALZA Common Stock to be
issued in the Merger (the "Registration Statement") as it relates to SEQUUS, at
the time the Registration Statement is declared effective by the SEC, shall not
contain any untrue statement of a material fact or omit to state any material
fact required to be stated therein or necessary in order to make the statements
therein not misleading. The information supplied by SEQUUS for inclusion in the
Proxy Statement/Prospectus to be sent to the stockholders of SEQUUS in
connection with the SEQUUS Special Meeting (such Proxy Statement/Prospectus, as
amended and supplemented is referred to herein as the "Proxy
Statement/Prospectus"), at the date the Proxy Statement/Prospectus is first
mailed to stockholders and at the time of the SEQUUS special meeting shall not
contain any untrue statement of a material fact or omit to state any material
fact required to be stated therein or necessary in order to make the statements
therein, in light of the circumstances under which they were made, not
misleading.
 
3.25 Pooling of Interests. SEQUUS has provided to its independent auditors all
information requested by such auditors to assess whether the Merger can
properly be accounted for as a pooling of interests, and has fully cooperated
with its independent auditors with respect to all reasonable requests made in
connection with such assessment. To the knowledge of SEQUUS, after consultation
with its independent auditors, none of SEQUUS, any of its Subsidiaries or any
of their respective directors, officers or stockholders has taken any action or
failed to take any action, which action or failure would prevent ALZA from
accounting for the Merger as a pooling of interests.
 
                                      A-22
<PAGE>
 
3.26 Title to Property. SEQUUS and its Subsidiaries have good and valid title
to all of their respective properties, interests in properties and assets, real
and personal, reflected in the SEQUUS Balance Sheet or acquired after the
Reference Date (except for tangible personal property, inventory, cash, cash
equivalents, short term investments or trade accounts receivable disposed of in
the ordinary course of business consistent with past practice or as permitted
by this Agreement since the Reference Date), and have valid leasehold interests
in all leased properties and assets, in each case free and clear of all
mortgages, liens, pledges, charges or encumbrances of any kind or character,
except (i) liens for current taxes not yet due and payable, (ii) such
imperfections of title, liens and easements as do not and will not materially
detract from or interfere with the use of the properties subject thereto or
affected thereby, or otherwise materially impair business operations involving
such properties, (iii) liens securing debt reflected on the SEQUUS Balance
Sheet, (iv) liens recorded pursuant to any Environmental Law or (v) liens which
would not, individually or in the aggregate, have a SEQUUS Material Adverse
Effect. Section 3.26 of the SEQUUS Disclosure Statement identifies each parcel
of real property owned or leased by SEQUUS or any of its Subsidiaries.
 
3.27 Year 2000 Compliance. SEQUUS is Year 2000 Compliant, as that term is
defined below, and there are no foreseeable expenses or other liabilities
associated with the process of securing full Year 2000 Compliance except for
any noncompliance that would not be reasonably expected to cause a SEQUUS
Material Adverse Effect. "Year 2000 Compliant" means that such hardware or
software produced, used, or provided by SEQUUS or any of its subsidiaries or
material contractors, vendors, or manufacturers, including, but not limited to,
microcode, firmware, system and application programs, files, databases,
computer services, and microcontrollers, including those embedded in computer
and non-computer equipment (the "Computer Systems") will:
 
  (a) process date data from at least the years 1900 through 2101 without
  error or interruption;
 
  (b) maintain functionality with respect to the introduction, processing, or
  output of records containing dates falling on or after January 1, 2000; and
 
  (c) be interoperable with other software or hardware which may deliver
  records to, receive records from, or interact with such Computer Systems in
  the course of conducting the business of SEQUUS, including processing data
  and manufacturing the products of SEQUUS.
 
                                   ARTICLE IV
 
             REPRESENTATIONS AND WARRANTIES OF ALZA AND MERGER SUB
 
ALZA and Merger Sub make to SEQUUS the representations and warranties contained
in this Article IV, in each case subject to the exceptions set forth in the
disclosure statement, dated as of the date hereof, delivered by ALZA to SEQUUS
prior to the execution of this Agreement (the "ALZA Disclosure Statement"). The
ALZA Disclosure Statement shall be arranged in schedules corresponding to the
numbered Sections of this Article IV, and the disclosure in any section of the
ALZA Disclosure Statement shall qualify only the corresponding Section of this
Article IV, unless it is reasonably apparent that the disclosed contract,
event, fact, circumstance or other matter could relate to other representations
or warranties or the matters covered thereby.
 
                                      A-23
<PAGE>
 
4.1 Organization, Etc.
 
(a) Each of ALZA and its Subsidiaries (the "ALZA Subsidiaries") is a
corporation duly organized, validly existing and in good standing under the
laws of the jurisdiction of its incorporation and has all requisite power and
authority to own, lease and operate its properties and to carry on its business
as now being conducted. ALZA and each ALZA Subsidiary are duly qualified as a
foreign Person to do business, and are each in good standing, in each
jurisdiction where the character of its owned or leased properties or the
nature of its activities makes such qualification necessary, except where the
failure to be so qualified or in good standing would not, individually and in
the aggregate, have an ALZA Material Adverse Effect. None of ALZA nor any ALZA
Subsidiary is in violation of any provision of its certificate of
incorporation, bylaws or any other charter document. For the purposes of this
Agreement, "ALZA Material Adverse Effect" means any change, event or effect
that is materially adverse to the business, prospects, financial condition or
results of operations of ALZA and the ALZA Subsidiaries taken as a whole;
provided, however, that (i) any adverse change, event or effect arising from or
relating to general business or economic conditions which does not affect ALZA
in a materially disproportionate manner shall not be deemed to constitute, and
shall not be taken into account in determining whether there has been, an "ALZA
Material Adverse Effect"; (ii) any adverse change, event or effect relating to
or affecting the pharmaceutical industry generally, or relating to or affecting
the sale, marketing or development of pharmaceuticals generally, which does not
affect ALZA in a materially disproportionate manner shall not be deemed to
constitute, and shall not be taken into account in determining whether there
has been an "ALZA Material Adverse Effect"; and (iii) any adverse change, event
or effect arising from or relating to the announcement or pendency of the
Merger shall not be deemed to constitute, and shall not be taken into account
in determining whether there has been, an "ALZA Material Adverse Effect";
provided further that the failure of ALZA to meet the published estimates,
expectations or projections of financial analysts shall not in itself
constitute an "ALZA Material Adverse Effect".
 
(b) Neither ALZA nor the ALZA Subsidiaries is in violation of any provision of
its certificate of incorporation, bylaws or other charter documents.
 
(c) Neither ALZA nor any of the ALZA Subsidiaries owns any capital stock or
other securities of SEQUUS.
 
4.2 Authority Relative to this Agreement. Each of ALZA and Merger Sub has full
corporate power and authority to execute and deliver this Agreement and to
consummate the Merger and the other transactions contemplated hereby. The
execution and delivery of this Agreement and the consummation of the Merger and
the other transactions contemplated hereby have been duly and validly
authorized by the board of directors of each of ALZA and Merger Sub and no
other corporate proceedings on the part of either ALZA or Merger Sub are
necessary to authorize this Agreement or to consummate the Merger and the other
transactions contemplated hereby. This Agreement has been duly and validly
executed and delivered by ALZA and Merger Sub and, assuming due authorization,
execution and delivery by SEQUUS, constitutes a valid and binding agreement of
each of ALZA and Merger Sub, enforceable against each of them in accordance
with its terms, except to the extent that its enforceability may be limited by
applicable bankruptcy, insolvency, reorganization, moratorium or other laws
affecting the enforcement of creditors' rights generally or by general
equitable principles.
 
                                      A-24
<PAGE>
 
4.3 No Violations, Etc. No filing with or notification to, and no permit,
authorization, consent or approval of, any Government Entity is necessary on
the part of either ALZA or Merger Sub for the consummation by ALZA or Merger
Sub of the Merger or the other transactions contemplated hereby, except for (i)
the filing of the Certificate of Merger as required by Delaware Law, (ii) the
filing with the SEC and the effectiveness of the Registration Statement, (iii)
the applicable requirements of the Exchange Act, state securities or "blue sky"
laws, state takeover laws and the listing requirements of the NYSE and (iv) any
filings required under and in compliance with the HSR Act or any antitrust laws
of any foreign country. Neither the execution and delivery of this Agreement,
nor the consummation of the Merger or the other transactions contemplated
hereby, nor compliance by ALZA and Merger Sub with all of the provisions hereof
will (i) conflict with or result in any breach of any provision of the
certificate of incorporation, bylaws or other charter documents of ALZA or any
ALZA Subsidiary, (ii) violate any material order, writ, injunction, decree,
statute, rule or regulation applicable to ALZA or any ALZA Subsidiary, or by
which any of their properties or assets may be bound, or (iii) result in a
violation or breach of, or constitute (with or without due notice or lapse of
time or both) a default, or give rise to any right of termination,
cancellation, acceleration, redemption or repurchase under, any of the terms,
conditions or provisions of any material note, bond, mortgage, indenture, deed
of trust, license, lease, agreement or other instrument or obligation to which
ALZA or any ALZA Subsidiary is a party or by which any of them or any of their
properties or assets may be bound.
 
4.4 Capitalization. (a) The authorized capital stock of ALZA consists of
300,000,000 shares of Common Stock, $.01 par value, of which there were
87,064,060 shares issued and outstanding as of September 30, 1998, and 100,000
shares of Preferred Stock, $.01 par value, of which no shares are issued or
outstanding. The authorized capital stock of Merger Sub consists of 10,000
shares of Common Stock, $.0001 par value, 100 of which, as of the date hereof,
are issued and outstanding and are held by ALZA. Merger Sub was formed for the
purpose of consummating the Merger and has no material assets or liabilities
except as necessary for such purpose. All outstanding shares of ALZA Common
Stock are (and the ALZA Common Stock to be issued in the Merger will, when
issued, be) duly authorized, validly issued, fully paid and nonassessable and
are not (and will not be) subject to preemptive rights created by statute, the
certificate of incorporation or bylaws of ALZA or any agreement to which ALZA
is a party or by which it is bound.
 
(b) Except as referred to in Section 4.4(a) hereof, there are no equity
securities of any class of ALZA, or any securities convertible into or
exercisable for any such equity securities, issued, reserved for issuance or
outstanding. There are no warrants, options, convertible securities, calls,
rights, stock appreciation rights, preemptive rights, rights of first refusal,
or agreements or commitments of any nature obligating ALZA to issue, deliver or
sell, or cause to be issued, delivered or sold, additional shares of capital
stock or other equity interests of ALZA, or obligating ALZA to grant, issue,
extend, accelerate the vesting of, or enter into, any such warrant, option,
convertible security, call, right, stock appreciation right, preemptive right,
right of first refusal, agreement or commitment.
 
4.5 Registration Statement; Proxy Statement/Prospectus. The information
supplied by ALZA for inclusion or incorporation by reference in the
Registration Statement as it relates to ALZA or Merger Sub, at the time the
Registration Statement is declared effective, shall not contain any untrue
statement of a material fact or omit to state any material fact required to be
stated therein or
 
                                      A-25
<PAGE>
 
necessary in order to make the statements therein not misleading. The
information supplied by ALZA for inclusion in the Proxy Statement/Prospectus,
at the date the Proxy Statement/Prospectus is first mailed to stockholders and
at the time of the SEQUUS Special Meeting shall not contain any untrue
statement of a material fact or omit to state any material fact required to be
stated therein or necessary in order to make the statements therein, in light
of the circumstances under which they were made, not misleading. If at any time
prior to the Effective Time any event with respect to ALZA or any ALZA
Subsidiary shall occur which is required to be described in the Registration
Statement or Proxy Statement/Prospectus, such event shall be so described, and
an amendment or supplement shall be promptly filed with the SEC and, as
required by law, disseminated to the shareholders of SEQUUS.
 
4.6 SEC Filings. ALZA has filed with the SEC all required forms, reports,
registration statements and documents required to be filed by it with the SEC
(collectively, all such forms, reports, registration statements and documents
filed after January 1, 1995 are referred to herein as the "ALZA SEC Reports"),
all of which complied as to form when filed in all material respects with the
applicable provisions of the Securities Act and the Exchange Act, as the case
may be. Accurate and complete copies of the ALZA SEC reports have been made
available to SEQUUS. As of their respective dates the ALZA SEC Reports
(including documents incorporated by reference therein and all exhibits and
schedules thereto) did not contain any untrue statement of a material fact or
omit to state a material fact required to be stated therein or necessary to
make the statements therein, in light of the circumstances under which they
were made, not misleading.
 
4.7 Compliance with Laws. Neither ALZA nor any ALZA Subsidiary has violated or
failed to comply with any statute, law, ordinance, rule or regulation
(including, without limitation, relating to the export or import of goods or
technology) of any foreign, federal, state or local government or any other
governmental department or agency, except where any such violations or failures
to comply would not, individually or in the aggregate, have an ALZA Material
Adverse Effect. ALZA and Merger Sub have all permits, licenses and franchises
from governmental agencies required to conduct their businesses as now being
conducted and as proposed to be conducted, except for those the absence of
which would not, individually or in the aggregate, have an ALZA Material
Adverse Effect.
 
4.8 Financial Statements. Each of the consolidated financial statements
(including, in each case, any related notes thereto) contained in the ALZA SEC
Reports (the "ALZA Financial Statements"), (x) was prepared in accordance with
GAAP applied on a consistent basis throughout the periods involved (except as
may be indicated in the notes thereto or, in the case of unaudited interim
financial statements, as may be permitted by the SEC on Form 10-Q under the
Exchange Act) and (y) fairly presented the consolidated financial position of
ALZA and its Subsidiaries as at the respective dates thereof and the
consolidated results of its operations and cash flows for the periods
indicated, consistent with the books and records of ALZA, except that the
unaudited interim financial statements were or are subject to normal and
recurring year-end adjustments which were not, or are not expected to be,
material in amount. The balance sheet of ALZA contained in ALZA's Form 10-Q for
the quarter ended June 30, 1998 is hereinafter referred to as the "ALZA Balance
Sheet."
 
4.9  Absence of Undisclosed Liabilities.  Neither ALZA nor any of its
Subsidiaries has any liabilities (absolute, accrued, contingent or otherwise)
other than (i) liabilities included in the ALZA
 
                                      A-26
<PAGE>
 
Balance Sheet and the related notes to the financial statements, (ii) normal or
recurring liabilities incurred since June 30, 1998 in the ordinary course of
business consistent with past practice, which, individually or in the
aggregate, are not or would not be reasonably likely to have, an ALZA Material
Adverse Effect, and (iii) liabilities under this Agreement.
 
4.10 Absence of Changes or Events. Except as contemplated by this Agreement,
since June 30, 1998, no ALZA Material Adverse Effect has occurred.
 
4.11 Litigation.
 
(a) Except as set forth in the ALZA SEC Reports, there is no Action pending or,
to the knowledge of ALZA, threatened against ALZA or any of its Subsidiaries,
or any of their respective officers and directors (in their capacities as
such), or involving any of their assets, before any court, or governmental or
regulatory authority or body, or arbitration tribunal, except for those Actions
which, individually or in the aggregate, would not have an ALZA Material
Adverse Effect. As of the date of this Agreement, there is no Action pending
or, to the knowledge of ALZA, threatened which in any manner challenges, seeks
to, or is reasonably likely to prevent, enjoin, alter or delay the transactions
anticipated by this Agreement.
 
(b) There is no outstanding judgment, order, writ, injunction or decree of any
court, governmental agency or arbitration tribunal in a proceeding to which
ALZA, any Subsidiary of ALZA or any of their assets is a party, or by which
ALZA, any ALZA Subsidiary or any of their assets is bound.
 
4.12 Officer's Certificate as to Tax Matters. ALZA knows of no reason why it
will be unable to deliver to Cooley Godward LLP and Heller Ehrman White &
McAuliffe at the Closing an Officer's Certificate in form sufficient to enable
each such counsel to render the opinions required by Section 6.5.
 
4.13 Pooling of Interests. ALZA has provided to its independent auditors all
information requested by such auditors to assess whether the Merger can
properly be accounted for as a pooling of interests, and has fully cooperated
with its independent auditors with respect to all reasonable requests made in
connection with such assessment. To the knowledge of ALZA, after consultation
with its independent auditors, none of ALZA, any of its Subsidiaries or any of
their respective directors, officers or stockholders has taken any action or
failed to take any action, which action or failure would prevent ALZA from
accounting for the Merger as a pooling of interests.
 
4.14 Taxes. None of ALZA or its Subsidiaries is aware of any reason why the
Merger will fail to qualify as a reorganization under the provisions of Section
368(a) of the Code.
 
4.15 Contracts and Commitments.
 
(a) The agreements listed in Section 4.15(a) of the ALZA Disclosure Statement
constitute all of the material agreements relating to rights to commercialize
ALZA's DUROS leuprolide, Ethyol, Ditropan, Ditropan XL, or Duragesic products
(the "Identified Products").
 
(b) Neither ALZA nor any of its Subsidiaries, nor to ALZA's knowledge any other
party to any material agreement, contract or commitment to which ALZA or any of
its Subsidiaries is a party (an "ALZA Contract"), is in beach, violation or
default under, or has received notice that it has
 
                                      A-27
<PAGE>
 
breached, violated or defaulted under (nor does there exist any condition under
which, with the passage of time or the giving of notice or both, could
reasonably be expected to cause such a breach, violation or default under), any
ALZA Contract, other than any breaches, violations or defaults which
individually or in the aggregate would not have an ALZA Material Adverse
Effect.
 
(c) Each ALZA Contract is a valid, binding and enforceable obligation of ALZA
and, to ALZA's knowledge, of the other party or parties thereto, in accordance
with its terms, and in full force and effect, except where the failure to be
valid, binding, enforceable and in full force and effect would not have an ALZA
Material Adverse Effect and to the extent enforcement may be limited by
applicable bankruptcy, insolvency, moratorium or other laws affecting the
enforcement of creditors' rights generally or by general principles of equity
or any competition laws of the European Union.
 
4.16 Intellectual Property Rights.
 
(a)  ALZA and the ALZA Subsidiaries own or have the right to use all
intellectual property which is material to the conduct of their respective
businesses (such intellectual property and such rights are collectively
referred to herein as the "ALZA IP Rights").
 
(b)  Neither the manufacture, marketing, license, sale or use by ALZA of any
Identified Product, nor the current use by ALZA or its Subsidiaries of ALZA's
OROS, D-TRANS or DUROS Technology the ("Identified Technology"), violates or
would violate in any material respect any license or agreement between ALZA or
any of its Subsidiaries and any other Persons and there is no pending or
threatened claim or litigation contesting the validity, ownership or right to
use, sell, license or dispose of any of the intellectual property rights
relating to any of the Identified Products or Identified Technology, or
asserting that the proposed use, sale, license or disposition thereof, or the
manufacture, use or sale of any Identified Products by ALZA or any of its
Subsidiaries, conflicts or will conflict with the rights of any other Person,
except as would not, individually or in the aggregate, have an ALZA Material
Adverse Effect.
 
4.17 FDA Matters.
 
(a) To ALZA's knowledge, the testing, manufacture, storage, distribution, use,
promotion and sale of ALZA's and ALZA's Subsidiaries' products by ALZA and its
Subsidiaries and contractors has been performed and is performed in substantial
compliance with all applicable requirements under the FDCA and the CSA,
including those relating to investigational use, premarket clearance, good
manufacturing practices, labeling, advertising, record keeping, filing of
reports, and security, except as would not, individually or in the aggregate,
have an ALZA Material Adverse Effect.
 
(b) With respect to the pending New Drug Application for the OROS oxybutynin
product, ALZA has, to its knowledge, complied with all applicable requirements
in the submission of such application, is not aware of any facts, circumstances
or events that could reasonably be expected to prevent such application from
being approved, and has not been informed by the FDA that such product would
not be approved within the period identified in Section 4.17 of the ALZA
Disclosure Statement.
 
                                      A-28
<PAGE>
 
                                   ARTICLE V
 
                                   COVENANTS
 
5.1 Conduct of Business During Interim Period.
 
(a) Except as contemplated or required by this Agreement or as expressly
consented to in writing by ALZA, during the period from the date of this
Agreement to the Effective Time, each of SEQUUS and its Subsidiaries will (i)
conduct its operations in all material respects according to its ordinary and
usual course of business consistent with past practice, (ii) use all
commercially reasonable efforts to preserve intact its business organization,
to keep available the services of its officers and employees in each business
function and to maintain satisfactory relationships with suppliers,
distributors, customers and others having business relationships with it, and
(iii) not take any action which could reasonably be expected to adversely
affect its ability to consummate the Merger or the other transactions
contemplated hereby. Without limiting the generality of the foregoing, and
except as otherwise contemplated by or expressly provided in this Agreement or
Section 5.1 of the SEQUUS Disclosure Statement, prior to the Effective Time
neither SEQUUS nor any of its Subsidiaries will, without the prior written
consent of ALZA, directly or indirectly, do any of the following:
 
  (i) enter into, violate, extend, amend or otherwise modify or waive any of
  the material terms of (A) any material partnership, joint venture, license
  or agreement relating to the joint development or transfer of technology or
  SEQUUS IP Rights or (B) except in the ordinary course of business and
  consistent with past practice, any other material agreements, commitments
  or contracts;
 
  (ii) split, combine or reclassify any shares of its capital stock;
 
  (iii) except as permitted in Section 5.2 of this Agreement, authorize or
  enter into any agreement in principle or an agreement with any other person
  with respect to (A) any plan of liquidation or dissolution with respect to
  SEQUUS or a SEQUUS Subsidiary, (B) any acquisition or disposition of a
  material amount of assets or securities, except purchases or sales of
  inventory and equipment in the ordinary course of business consistent with
  past practice, or (C) any material change in capitalization other than the
  sale and delivery of shares of SEQUUS Common Stock held or to be held in
  SEQUUS' 401(k) Pension and Profit Sharing Plan, the issuance and delivery
  and/or sale of shares of SEQUUS Common Stock pursuant to the exercise of
  stock options, the grant of options to purchase up to a number of shares of
  SEQUUS Common Stock equal to 555 multiplied by the number of days from the
  date of this Agreement to the Effective Time in connection with the hiring
  and/or promotion of non-officer employees of SEQUUS or any of its
  Subsidiaries, and the issuance of shares of SEQUUS Common Stock issuable to
  participants in the SEQUUS Purchase Plan;
 
  (iv) fail to renew any insurance policy naming it as a beneficiary or a
  loss payee, or take any steps or fail to take any steps that would permit
  any insurance policy naming it as a beneficiary or a loss payee to be
  canceled, terminated or materially and adversely altered, except in the
  ordinary course of business and consistent with past practice and following
  written notice to ALZA;
 
                                      A-29
<PAGE>
 
  (v) maintain its books and records in a manner other than in the ordinary
  course of business and consistent with past practice;
 
  (vi) enter into any hedging, option, derivative or other similar
  transaction or any foreign exchange position or contract for the exchange
  of currency other than in the ordinary course of business and consistent
  with past practice;
 
  (vii) institute any change in its accounting methods, principles or
  practices other than as required by GAAP, or the rules and regulations
  promulgated by the SEC, or revalue any assets, including without
  limitation, writing down the value of inventory or writing off notes or
  accounts receivables other than as required by GAAP;
 
  (viii) in respect of any Taxes, make or change any material election,
  change any accounting method, enter into any closing agreement, settle any
  material claim or assessment, or consent to any extension or waiver of the
  limitation period applicable to any material claim or assessment except as
  required by applicable law;
 
  (ix) take any action, or fail to take any action, which could reasonably be
  expected to prevent ALZA from accounting for the Merger as a pooling of
  interests;
 
  (x) except as reasonably required due to medical or regulatory
  considerations, as required by a Government Entity, or as required due to a
  lack of available funds (and only after SEQUUS shall have provided ALZA
  with reasonable notice of any such requirement), suspend, terminate or
  otherwise discontinue any planned or ongoing material research and
  development activities, programs, clinical trials or other such activities
  with respect to the products listed in Section 5.1(x) of the SEQUUS
  Disclosure Statement (the "Material Products");
 
  (xi) except as required by a Government Entity, make any material amendment
  to any New Drug Application with the FDA, Supplemental New Drug Application
  with the FDA or their foreign equivalents; or
 
  (xii) take or agree to take, any of the actions described in Section
  3.10(a), (b) and (f) through (k) above, or any action which would
  reasonably be expected to result in the conditions in Section 7.2(a) and
  (b) not being satisfied.
 
(b) During the period from the date of this Agreement to the Effective Time,
neither ALZA nor any of its Subsidiaries will (i) take any action which could
reasonably be expected to adversely affect ALZA's ability to consummate the
Merger or the other transactions contemplated hereby, (ii) take any action
which could reasonably be expected to prevent ALZA from accounting for the
Merger as a pooling of interests, (iii) take, or agree to take, any action
which could reasonably be expected to result in any of the conditions specified
in Sections 7.1(a) and (b) not being satisfied or (iv) consummate, or agree to
consummate, (A) any transaction or series of related transactions to acquire
shares representing a controlling interest in any Person pursuant to a tender
offer, exchange offer, Merger, consolidation, share exchange, acquisition of
stock or other business combination or acquisition (a "Business Combination")
in which the aggregate consideration paid or payable by ALZA and its
Subsidiaries is or would be in excess of $750 million or (B) any other
transaction or series of related transactions to acquire or license assets or
rights in which the aggregate consideration paid or payable by ALZA and its
Subsidiaries is or would be in excess of $750 million,
 
                                      A-30
<PAGE>
 
in each case, determined as of the date of the definitive agreement relating to
such Business Combination or other transaction.
 
5.2 No Solicitation.
 
(a) SEQUUS shall not, and shall cause its Subsidiaries not to, and shall use
its best efforts to cause its and its Subsidiaries' respective officers and
directors not to, and shall use commercially reasonable efforts to cause its
non-officer employees, investment bankers, attorneys or other agents retained
by or acting on behalf of SEQUUS or any of its Subsidiaries not to: (i)
initiate, solicit or knowingly encourage, directly or indirectly, any inquiries
or the making of any proposal that constitutes or is reasonably likely to lead
to any Acquisition Proposal (as defined in Section 5.2(c) hereof), (ii) engage
in negotiations or discussions (other than to advise as to the existence or
substance of the restrictions set forth in this Section 5.2) with, or furnish
any non-public information or data to, any third party relating to an
Acquisition Proposal, or (iii) enter into any agreement with a Potential
Acquiror (other than a confidentiality, standstill and nonsolicitation
agreement which satisfies the requirements set forth below) with respect to any
Acquisition Proposal or approve any Acquisition Proposal. Notwithstanding
anything to the contrary contained in this Section 5.2 or in any other
provision of this Agreement, SEQUUS and its board of directors (i) may
participate in discussions or negotiations with or furnish non-public
information or data to any third party that has made an unsolicited Acquisition
Proposal (a "Potential Acquiror") and/or (ii) subject to the provisions of
Section 5.2(b), may approve or accept an unsolicited Acquisition Proposal if
the board of directors of SEQUUS determines in good faith (A) after receiving
written advice from its financial advisor, that such Acquisition Proposal is a
Superior Proposal (as defined in Section 5.2(d) hereof), and (B) following
consultation with outside legal counsel, that the failure to participate in
such discussions or negotiations or to furnish such information or approve or
accept an Acquisition Proposal would violate the board's fiduciary duties under
applicable law. SEQUUS agrees that any non-public information furnished to a
Potential Acquiror will be furnished pursuant to a confidentiality, standstill
and nonsolicitation agreement containing provisions at least as favorable to
SEQUUS as the confidentiality, standstill and nonsolicitation provisions of the
Confidentiality Agreements (as defined in Section 5.3). In the event that
SEQUUS shall determine to provide any information as described above, or shall
receive any Acquisition Proposal (or any material amendment to an Acquisition
Proposal previously received), it shall promptly, and in any event within 24
hours, inform ALZA in writing as to that fact and shall furnish to ALZA the
identity of the recipient of such information to be provided and/or the
Potential Acquiror and the terms of such Acquisition Proposal (or material
amendment).
 
(b) Except as provided in this Section 5.2, the board of directors of SEQUUS
shall recommend to its stockholders approval of this Agreement and the Merger.
The board of directors of SEQUUS shall not (i) withdraw or modify or propose to
withdraw or modify, in any manner adverse to ALZA, its approval and
recommendation of this Agreement and the Merger or (ii) approve or recommend,
or propose to approve or recommend, any Acquisition Proposal unless, in each
case, the board has (x) determined that such Acquisition Proposal is a Superior
Proposal, (y) determined in good faith, following consultation with outside
legal counsel, that the failure to take such action would violate the board's
fiduciary duties under applicable law and (z) given at least 72 hours prior
written notice to ALZA of its determination under clause (y) of this Section
5.2(b).
 
                                      A-31
<PAGE>
 
(c) For purposes of this Agreement, "Acquisition Proposal" shall mean any bona
fide proposal (which may be subject to a "due diligence" condition), whether in
writing or otherwise, made by a Third Party (as defined below) for: (i) a
transaction or series of related transactions pursuant to which any Person (or
any group of Persons acting in concert for the specific purpose of allowing
SEQUUS to evade the provisions of this Section 5.2) other than ALZA, SEQUUS or
Merger Sub, or any affiliate thereof (a "Third Party"), acquires or would
acquire (upon completion of such transaction or series of related transactions)
shares (or securities exercisable for or convertible into shares) representing
more than twenty percent (20%) of the outstanding shares of SEQUUS Common
Stock, pursuant to a tender offer or exchange offer or otherwise; (ii) a
Merger, consolidation, share exchange or other business combination involving
SEQUUS or any of its subsidiaries if, upon consummation of such Merger,
consolidation, share exchange or other business combination, such Third Party
(or its shareholders) owns or would own more than twenty percent (20%) of the
outstanding equity securities of SEQUUS or any of its subsidiaries or the
entity surviving such Merger or business combination or resulting from such
consolidation; (iii) any other transaction or series of related transactions
pursuant to which such Third Party acquires or would acquire (upon completion
of such transaction or series of related transactions) primary control of
assets of SEQUUS or any of its subsidiaries (including, for this purpose,
SEQUUS IP Rights or SEQUUS product rights and outstanding equity securities of
subsidiaries of SEQUUS) if the aggregate dollar value of the consideration
proposed to be paid by such Third Party to SEQUUS or its Subsidiary in such
transaction exceeds $100 million; or (iv) any transaction or series of related
transactions pursuant to which such Third Party acquires or would acquire (upon
completion of such transaction or series of related transactions) control of
the board of directors of SEQUUS or by which nominees of such Third Party are
(or would be) elected or appointed to a majority of the seats on the board of
directors of SEQUUS.
 
(d) The term "Superior Proposal" means any Acquisition Proposal, made in
writing and not initiated, solicited or encouraged in violation of Section
5.2(a) of this Agreement, on terms which the board of directors of SEQUUS
determines in good faith to be more favorable to SEQUUS and its stockholders or
to its stockholders than the Merger (after receiving the written advice of
SEQUUS' financial advisor that the value of the consideration provided for in
such proposal is superior to the value of the consideration provided for in the
Merger), for which financing, to the extent required, is then committed or
which, in the good faith judgment of the board of directors of SEQUUS, after
receiving written advice from its financial advisor, is reasonably capable of
being financed by the Potential Acquiror.
 
(e) SEQUUS shall not terminate, amend, modify or waive any provision of any
confidentiality or standstill agreement to which it or any of its Subsidiaries
is a party.
 
5.3 Access to Information. From the date of this Agreement until the Effective
Time, SEQUUS and ALZA will each afford to the other and their authorized
representatives (including counsel, environmental and other consultants,
accountants, auditors and agents) reasonable access during normal business
hours and upon reasonable notice to all of its facilities, personnel and
operations and to all of its and its Subsidiaries' books and records, will
permit the other and its authorized representatives to conduct inspections as
they may reasonably request and will instruct its officers and those of its
Subsidiaries to furnish such persons with such financial and operating data and
other
 
                                      A-32
<PAGE>
 
information with respect to its business and properties as they may from time
to time reasonably request, subject to the restrictions set forth in the
Confidentiality Agreements (as defined below). ALZA and Merger Sub agree that
each of them will treat any such information in accordance with the
Confidentiality Agreement, dated as of September 17, 1998, between ALZA and
SEQUUS and the Supplemental Nondisclosure Agreement, dated as of September 25,
1998 between ALZA and SEQUUS (together, the "Confidentiality Agreements"),
which Confidentiality Agreements shall remain in full force and effect in
accordance with their terms.
 
5.4 Special Meeting; Registration Statement; Board Recommendation.
 
(a) In order to consummate the Merger, SEQUUS, acting through its board of
directors, shall duly call, give notice of, convene and hold a Special Meeting
of the stockholders of SEQUUS for the purpose of considering and taking action
upon this Agreement (the "SEQUUS Special Meeting"). The SEQUUS Special Meeting
shall be held as soon as practicable after the Registration Statement has been
declared effective.
 
(b) As promptly as practicable after the execution of this Agreement, SEQUUS
and ALZA shall mutually prepare, and SEQUUS shall file with the SEC, a
preliminary form of the Proxy Statement/Prospectus. As promptly as practicable
following receipt of SEC comments on such preliminary Proxy
Statement/Prospectus, ALZA and SEQUUS shall mutually prepare a response to such
comments. Upon resolution of all comments, ALZA shall file the Registration
Statement with the SEC. ALZA and SEQUUS shall use all commercially reasonable
efforts to have the preliminary Proxy Statement/Prospectus cleared by the SEC
and the Registration Statement declared effective by the SEC as promptly as
practicable. ALZA shall also take any action required to be taken under
applicable state blue sky or securities laws in connection with ALZA Common
Stock to be issued in exchange for the shares of SEQUUS Common Stock. ALZA and
SEQUUS shall promptly furnish to each other all information, and take such
other actions (including without limitation using all commercially reasonable
efforts to provide any required consents of their respective independent
auditors), as may reasonably be requested in connection with any action by any
of them in connection with the preceding sentences of this Section 5.4(b).
Whenever any party learns of the occurrence of any event which is required to
be set forth in an amendment or supplement to the Proxy Statement/Prospectus,
the Registration Statement or any other filing made pursuant to this Section
5.4(b), ALZA or SEQUUS, as the case may be, shall promptly inform the other of
such occurrence and cooperate in filing with the SEC or its staff and/or
mailing to stockholders of SEQUUS such amendment or supplement.
 
(c) Subject to Section 5.2, the Proxy Statement/Prospectus shall contain the
unanimous recommendation of the board of directors of SEQUUS in favor of the
approval and adoption of this Agreement.
 
5.5 Commercially Reasonable Efforts.
 
(a) Subject to the terms and conditions herein provided, ALZA, Merger Sub and
SEQUUS shall use commercially reasonable efforts to take, or cause to be taken,
all actions and do, or cause to be done, all things necessary, proper or
appropriate under this Agreement, applicable laws and regulations to consummate
and make effective the transactions contemplated by this Agreement, including,
without
 
                                      A-33
<PAGE>
 
limitation, (i) promptly filing Notification and Report Forms under the HSR Act
with the Federal Trade Commission (the "FTC") and the Antitrust Division of the
Department of Justice (the "Antitrust Division") and responding as promptly as
practicable to any inquiries received from the FTC or the Antitrust Division
for additional information or documentation, (ii) using commercially reasonable
efforts to obtain all necessary governmental and private party consents,
approvals or waivers, and (iii) using commercially reasonable efforts to lift
any legal bar to the Merger. ALZA shall cause Merger Sub to perform all of its
obligations under this Agreement.
 
(b) Notwithstanding anything to the contrary in this Agreement, neither ALZA,
nor the Surviving Corporation, nor any of their Subsidiaries shall be required
to (i) divest, hold separate or license any material business(es), product
line(s) or asset(s), (ii) take any action or accept any limitation that could
reasonably be expected to have an ALZA Material Adverse Effect or a SEQUUS
Material Adverse Effect, or (iii) agree to any of the foregoing.
 
5.6 Public Announcements. Before issuing any press release or otherwise making
any public statement with respect to the Merger or any of the other
transactions contemplated hereby, ALZA, Merger Sub and SEQUUS agree to consult
with each other as to its form and substance, and agree not to issue any such
press release or general communication to employees or make any public
statement prior to obtaining the consent of the other (which shall not be
unreasonably withheld or delayed), except as may be required by applicable law
or by the rules and regulations of or listing agreement with the NYSE or Nasdaq
or as may otherwise be required by the NYSE, Nasdaq or the SEC.
 
5.7 Notification of Certain Matters.
 
(a) Each of SEQUUS and ALZA shall promptly notify the other party after
obtaining knowledge of the occurrence or non-occurrence of any event the
respective occurrence or non-occurrence of which would be likely to cause any
condition to the obligations of the notifying party to effect the Merger not to
be fulfilled. Each of SEQUUS and ALZA shall also give prompt notice to the
other of any communication received from any Person alleging that the consent
of such Person is or may be required in connection with the Merger or other
transactions contemplated hereby.
 
(b) SEQUUS will promptly provide ALZA with copies of any communication that is
issued, prepared or otherwise becomes available from the date of this Agreement
until the Effective Time which bears upon the regulatory status of the Material
Products or the facilities of SEQUUS or any of the Subsidiaries of SEQUUS or
the facilities of the material suppliers of SEQUUS including but not limited to
any warning letter, notice of violation, approval letter/order, non-approval
letter/order or withdrawal letter/order from a Government Entity respecting
their facilities or products.
 
(c) ALZA will provide SEQUUS with reasonable access to any communications that
are issued, prepared or otherwise become available from the date of this
Agreement until the Effective Time which bear upon the regulatory status of the
OROS oxybutynin product, including but not limited to any warning letter,
notice of violation, approval letter/order, non-approval letter/order, or
withdrawal letter/order from a Government Entity respecting such product.
 
                                      A-34
<PAGE>
 
5.8 Indemnification.
 
(a) The certificate of incorporation and bylaws of the Surviving Corporation
shall contain, and ALZA shall cause the Surviving Corporation to fulfill and
honor, the provisions with respect to indemnification and exculpation that are
substantially identical to those set forth in the certificate of incorporation
and bylaws of SEQUUS as of the date of this Agreement, which provisions shall
not be amended, repealed or otherwise modified for a period of six years from
the Effective Time in any manner that would adversely affect the rights
thereunder of any of the Indemnified Parties. In addition, ALZA shall cause the
Surviving Corporation to fulfill and honor the obligations of SEQUUS pursuant
to any indemnification agreements between SEQUUS and any of the Indemnified
Parties which are listed in Section 3.14 of the SEQUUS Disclosure Statement.
"Indemnified Parties" shall include each person who is or was a director or
officer of SEQUUS or any Subsidiary of SEQUUS at any time before the Effective
Time, and each person who serves or has in the past served at the request of
SEQUUS or any subsidiary of SEQUUS as a director, officer, trustee, partner,
fiduciary, employee or agent of another corporation, partnership, joint
venture, trust, pension or other employee benefit plan or enterprise at any
time before the Effective Time.
 
(b) For a period of six years after the Effective Time ALZA shall indemnify and
hold harmless the Indemnified Parties against and from any costs or expenses
(including attorneys' fees), judgments, fines, losses, claims, damages,
liabilities and amounts paid in settlement in connection with any claim,
action, suit, proceeding or investigation, whether civil, criminal,
administrative or investigative (and whether arising before or after the
Effective Time), to the extent arising out of or pertaining to any action or
omission in his or her capacity as a director or officer of SEQUUS arising out
of or pertaining to the transactions contemplated by this Agreement. In the
event of the commencement or assertion of any such claim, action, suit,
proceeding or investigation (whether arising before or after the Effective
Time), (i) any counsel retained by the Indemnified Parties for any period after
the Effective Time must be reasonably satisfactory to ALZA, (ii) after the
Effective Time, ALZA shall pay or cause to be paid the reasonable fees and
expenses of such counsel, promptly after statements therefor are received and
(iii) ALZA shall cause the Surviving Corporation to cooperate in the defense of
any such matter; provided, however, that neither ALZA nor the Surviving
Corporation shall be liable for any settlement effected without its written
consent (which consent shall not be unreasonably withheld or delayed); and
provided, further, that, in the event that any claim or claims for
indemnification are asserted or made within such six-year period, all rights to
indemnification in respect of any such claim or claims (and the matters giving
rise thereto) shall continue until the disposition of any and all such claims
(and the matters giving rise thereto). The Indemnified Parties as a group may
retain only one law firm (in addition to local counsel) to represent them with
respect to any single action unless any Indemnified Party determines in good
faith (after consultation with legal counsel) that there is, under applicable
standards of professional conduct, a conflict on any significant issue between
the positions of any two or more Indemnified Parties. In the event ALZA or the
Surviving Corporation or any of their respective successors or assigns (i)
consolidates with or merges into any other Person and shall not be the
continuing or surviving corporation or entity of such consolidation or Merger,
or (ii) transfers or conveys all or substantially all of its properties and
assets to any Person, then, and in each such case, to the extent necessary to
effectuate the purposes of this Section 5.8, proper provision shall be made so
that the successors and assigns of ALZA and the Surviving Corporation assume
the obligations set forth in this Section, and none of the actions described in
clause (i) or (ii) shall be taken until such provision is made.
 
                                      A-35
<PAGE>
 
(c) Without limiting any of the obligations of ALZA or the Surviving
Corporation set forth elsewhere in this Section 5.8, for a period of six years
after the Effective Time, ALZA shall cause the Surviving Corporation to
maintain in effect, to the extent available, directors' and officers' liability
insurance covering those persons who are currently covered by SEQUUS'
directors' and officers' liability insurance policy on terms comparable to
those applicable under the policy of directors' and officers' liability
insurance currently maintained by SEQUUS; provided, however, that in no event
shall ALZA or the Surviving Corporation be required to expend in excess of 150%
of the annual premium currently paid by SEQUUS for such coverage, and that if
the annual premiums of such insurance coverage exceed such amount, the
Surviving Corporation shall be obligated instead to obtain a policy with the
greatest coverage available for a cost not exceeding such amount.
 
(d) ALZA shall cause the Surviving Corporation to perform its obligations under
this Section 5.8 and shall, in addition, guarantee, as co-obligor with the
Surviving Corporation, the performance of such obligations by the Surviving
Corporation.
 
(e) Each Indemnified Party shall comply with the reasonable requests of the
Surviving Company or ALZA in defending or settling any action hereunder;
provided, however, that no proposed settlement of any such action need be
considered by any Indemnified Party unless (A) such settlement involves no
finding or admission of any liability by any Indemnified Party, and (B) the
sole relief provided in connection with such settlement is monetary damages
that are paid in full by the Surviving Corporation or ALZA.
 
(f) ALZA agrees to pay, or cause the Surviving Corporation to pay, all
expenses, including reasonable attorney's fees, that may be incurred by the
Indemnified Parties in successfully enforcing the indemnity and other rights
under this Section 5.8.
 
5.9 Expenses. ALZA and Merger Sub, on the one hand, and SEQUUS, on the other
hand, shall bear their respective expenses incurred in connection with this
Agreement, and the transactions contemplated hereby, including, without
limitation, the preparation, execution and performance of this Agreement and
the consummation of the transactions contemplated hereby and all fees and
expenses of their respective investment bankers, finders, brokers, agents,
representatives, counsel and accountants, except that expenses incurred in
printing, mailing and filing (including without limitation, SEC filing fees and
stock exchange listing application fees) the Proxy Statement/Prospectus shall
be shared equally between ALZA and SEQUUS.
 
5.10 Pooling of Interests Accounting.
 
(a) Each of ALZA and SEQUUS shall use commercially reasonable efforts to cause
the business combination to be effected by the Merger to be accounted for as a
pooling of interests. Each of ALZA and SEQUUS shall use commercially reasonable
efforts to cause its Affiliates not to take any action that would prevent ALZA
from accounting for the business combination to be effected by the Merger as a
pooling of interests.
 
(b) SEQUUS shall use commercially reasonable efforts to cause to be delivered
to SEQUUS a letter of SEQUUS' independent accountants, dated within two
business days prior to the Effective Time, regarding SEQUUS' accountants'
concurrence with SEQUUS' management's conclusion that no conditions exist
related to SEQUUS that would preclude ALZA from accounting for the Merger as a
 
                                      A-36
<PAGE>
 
pooling of interests if the Merger is consummated in accordance with this
Agreement. Such letter shall be in a form reasonably satisfactory to ALZA and
customary in scope and substance for letters delivered by independent public
accountants in connection with transactions of this type.
 
(c) ALZA shall use commercially reasonable efforts to cause to be delivered to
SEQUUS a letter of ALZA's independent accountants, dated within two business
days prior to the Effective Time, regarding ALZA's accountants' concurrence
with ALZA's management's and SEQUUS' management's conclusions, respectively, as
to the appropriateness of pooling of interests accounting for the Merger under
Accounting Principles Board Opinion No. 16 if consummated in accordance with
this Agreement.
 
5.11 Affiliate Agreements.
 
(a) Promptly after the execution and delivery hereof, SEQUUS shall deliver to
ALZA a list (reasonably satisfactory to counsel for ALZA) setting forth the
names of all persons who are expected to be, at the Effective Time, in SEQUUS'
reasonable judgment, Affiliates of SEQUUS. SEQUUS shall furnish such
information and documents as ALZA may reasonably request for the purpose of
reviewing such list. SEQUUS shall use commercially reasonable efforts to
deliver a written agreement in substantially the form of Exhibit B hereto (a
"SEQUUS Affiliate Agreement") executed by each person identified as an
Affiliate in the list furnished pursuant to this Section 5.11(a) as soon as
practicable after the execution of this Agreement and in any case shall deliver
such written agreements within 10 days after the date of this Agreement.
 
(b) Promptly after the execution and delivery hereof, ALZA shall deliver to
SEQUUS a list (reasonably satisfactory to counsel for SEQUUS) setting forth
names of all persons who are expected to be, at the Effective Time, in ALZA's
reasonable judgment, affiliates of ALZA under applicable SEC accounting
releases with respect to pooling of interests accounting treatment. ALZA shall
furnish such information and documents as SEQUUS may reasonably request for the
purpose of reviewing such list. ALZA shall use commercially reasonable efforts
to deliver a written agreement in substantially the form of Exhibit C hereto
(an "ALZA Affiliate Agreement") executed by each person identified as an
affiliate in the list furnished pursuant to this Section 5.11(b) as soon as
practicable after the execution of this Agreement and in any case shall deliver
such written agreements within 10 days after the date of this Agreement.
 
5.12 NYSE Listing. ALZA shall use commercially reasonable efforts to list on
the NYSE, upon official notice of issuance, the shares of ALZA Common Stock to
be issued in connection with the Merger.
 
5.13 Resignation of Directors and Officers. Prior to the Effective Time, SEQUUS
shall deliver to ALZA at no cost the resignations of such directors and
officers of SEQUUS and its Subsidiaries as ALZA shall specify at least ten
business days prior to the Closing, effective at the Effective Time.
 
5.14 Consents of ALZA's and SEQUUS' Accountants. Each of ALZA and SEQUUS shall
use commercially reasonable efforts to cause its independent accountants to
deliver to ALZA a consent, dated the date on which the Registration Statement
shall become effective, in form reasonably satisfactory to ALZA and customary
in scope and substance for consents delivered by independent public accountants
in connection with registration statements on Form S-4 under the Securities
Act.
 
                                      A-37
<PAGE>
 
5.15 Stock Options and Warrants.
 
(a) No later than 10 business days after the Effective Time, ALZA shall file
with the SEC a Registration Statement, on Form S-8 or other appropriate form
under the Securities Act, to register ALZA Common Stock issuable upon exercise
of the ALZA Exchange Options. ALZA shall use commercially reasonable efforts to
cause such Registration Statement to remain effective until the exercise or
expiration of such options.
 
(b) As soon as practicable after the Effective Time, ALZA shall deliver to each
person who holds an outstanding SEQUUS Option immediately before the Effective
Time a notice describing the assumption of SEQUUS Options set forth in Section
2.2(a) hereof.
 
(c) In connection with ALZA's assumption of the Warrants, ALZA shall make such
assumption by written instrument delivered to, and reasonably satisfactory to,
the holders of such Warrants.
 
5.16 Board of Directors. Effective as of the Effective Time, Dr. I. Craig
Henderson (if willing and able to serve) shall be appointed to the board of
directors of ALZA, as a member of Class III, to serve until the election of
such class of directors at an annual meeting of its stockholders.
 
5.17 Intentionally Omitted.
 
5.18 SEC Filings.
 
(a) SEQUUS will deliver promptly to ALZA true and complete copies of each
report, registration statement or statement mailed by it to its security
holders generally or filed by it with the SEC, in each case subsequent to the
date hereof and prior to the Effective Time.
 
(b) ALZA will deliver promptly to SEQUUS true and complete copies of each
report filed by it with the SEC subsequent to the date hereof and prior to the
Effective Time.
 
(c) Each party shall file a report on Form 8-K in compliance with Rule 13a-11
under the Exchange Act with respect to this Agreement including as exhibits to
such report this Agreement and such other agreements that such party shall
reasonably determine to be appropriate.
 
5.19 Employee Benefit Matters.
 
(a) Except as provided in Sections 5.19(b) and 5.19(c) and as provided in
Section 2.2(b) with respect to the ALZA Purchase Plan, ALZA shall ensure that
each person who is an employee of SEQUUS immediately prior to the Effective
Time (i) shall receive full service and vesting credit, under each applicable
employee benefit plan of ALZA in which such employee is eligible to participate
after the Effective Time (other than ALZA's bonus leave plan), for his or her
time of service to SEQUUS and its affiliates and predecessors, (ii) shall be
eligible to participate in all benefit plans of ALZA on the same terms and
conditions as other ALZA employees, and (iii) shall receive full credit under
the vacation, sick leave and paid time off policies of ALZA applicable to such
employee (other than ALZA's bonus leave plan) for all accrued and unused
vacation, sick leave and paid time off to which such employee is entitled under
the vacation, sick leave and paid time off policies of SEQUUS as of the
Effective Time; provided in each case such person is employed by ALZA or the
Surviving Corporation immediately after the Effective Time. ALZA shall cause to
be waived any pre-existing condition limitations, waiting periods or similar
limitations under each such employee benefit plan
 
                                      A-38
<PAGE>
 
and shall provide each such employee with credit for any co-payments previously
made and any deductibles or maximums previously satisfied.
 
(b) Subject to Sections 5.19, (c) and (d), ALZA need not make any payments or
contributions with respect to either the pre-Effective Time service or the pre-
1999 service of any employee described in Section 5.19(a) under any of its
employee benefit plans, including without limitation any payments under its
PACE bonus plan or contributions to its 401(k) plan or its retirement plan;
provided, however, that any severance benefits or health benefits payable to
any such employee who is employed by ALZA or the Surviving Corporation
immediately after the Effective Time shall be determined without regard to this
Section 5.19(b). SEQUUS shall terminate the SEQUUS Pharmaceuticals, Inc.,
Profit Sharing 401(k) Plan effective immediately prior to the Effective Time.
Prior to the termination of the Profit Sharing 401(k) Plan, SEQUUS will
allocate to each participant's account a matching contribution, in the form of
SEQUUS Common Stock, in an amount not to exceed 50% of the first 5% of the
compensation contributed by participating employees to such accounts during
1998; provided, however, that the amount of such matching contribution may be
increased in an amount not to exceed $10,000 per week, to account for any
period in 1998 during which SEQUUS 401(k) plan participants are not eligible to
continue their participation in the SEQUUS 401(k) plan due to its termination.
 
(c) With respect to any employee described in Section 5.19(a) who has accrued
partial credit toward a paid sabbatical leave under SEQUUS' sabbatical leave
policy, ALZA shall provide the employee with the same sabbatical leave benefit
once the employee's aggregate service for SEQUUS and ALZA would have resulted
in the accrual of full credit toward such benefit under SEQUUS' sabbatical
leave policy; provided, however, that such service for ALZA shall not be
credited simultaneously under ALZA's bonus leave plan.
 
(d) The Surviving Corporation shall terminate its cafeteria plan (within the
meaning of Section 125 of the Code) as of the later of the Effective Time or
December 31, 1998. ALZA shall permit each employee described in Section 5.19(a)
to participate in the ALZA cafeteria plan and plans funded through such
cafeteria plan, and participants in the terminated SEQUUS cafeteria plan shall
be permitted to utilize remaining account balances in such plan in accordance
with its terms.
 
(e) SEQUUS shall be liable for any liability under the Worker Adjustment and
Retraining Notification Act, 29 U.S.C. (S) 2101 et seq. ("WARN") (or any
similar foreign or domestic laws), including, but not limited to all severance
and other obligations (whether to give notice, to pay money, or to provide
benefits), with respect to the employment or termination of employment of
employees prior to the Effective Time. If requested in writing by ALZA, SEQUUS
agrees to provide notices both to employees and the necessary Government
Entities, in compliance with WARN, at least 60 days prior to the Effective
Time. SEQUUS shall deliver to ALZA a copy of the draft notices to be issued in
accordance with WARN (or any similar foreign or domestic laws), which notices
shall be subject to ALZA's review, comment and approval, which approval shall
not be unreasonably withheld.
 
                                      A-39
<PAGE>
 
                                   ARTICLE VI
 
                  CONDITIONS TO THE OBLIGATIONS OF EACH PARTY
 
The respective obligations of each party to this Agreement to effect the Merger
shall be subject to the fulfillment of each of the following conditions, any
one or more of which may be waived in writing by all the parties hereto:
 
6.1 Registration Statement. The Registration Statement shall have become
effective in accordance with the provisions of the Securities Act. No stop
order suspending the effectiveness of the Registration Statement shall have
been issued by the SEC and remain in effect and no proceedings for such purpose
shall be pending before or threatened by the SEC.
 
6.2 Stockholder Approval. The approval of a majority of the outstanding shares
of SEQUUS Common Stock for adoption of this Agreement shall have been obtained
at the SEQUUS Special Meeting or any adjournment or postponement thereof.
 
6.3 Listing of Additional Shares. The ALZA Common Stock issuable in connection
with the Merger shall have been approved for listing subject to official notice
of issuance on the NYSE.
 
6.4 Governmental Clearances. The waiting period applicable to consummation of
the Merger under the HSR Act shall have expired or been terminated. Other than
the filing of the Certificate of Merger which shall be accomplished as provided
in Section 1.2, all authorizations, consents, orders or approvals of, or
declarations or filings with, or expirations of waiting periods imposed by, any
Government Entity the failure of which to obtain or comply with would be
reasonably likely to have a SEQUUS Material Adverse Effect or an ALZA Material
Adverse Effect shall have been obtained or filed.
 
6.5 Tax Matters. Each of ALZA and Merger Sub shall have received an opinion of
Heller Ehrman White & McAuliffe, counsel to ALZA and Merger Sub, and SEQUUS
shall have received an opinion of Cooley Godward LLP, counsel to SEQUUS, each
such opinion dated as of the Effective Time, substantially to the effect that
on the basis of the facts, representations and assumptions set forth in such
opinions, (i) the Merger will be treated as a reorganization within the meaning
of Section 368(a) of the Code; (ii) each of ALZA, Merger Sub and SEQUUS will be
a party to such reorganization within the meaning of Section 368(b) of the
Code; and (iii) except with respect to cash received in lieu of fractional
share interest in ALZA Common Stock, no gain or loss will be recognized, for
United States federal income tax purposes, by a stockholder of SEQUUS as a
result of the Merger with respect to the shares of SEQUUS Common Stock
converted into ALZA Common Stock. If counsel to either ALZA or SEQUUS does not
render such opinion, this condition shall nonetheless be deemed to be satisfied
with respect to such party if counsel to the other party renders such opinion
in the required form to such party.
 
6.6 Statute or Decree. No writ, order, temporary restraining order, preliminary
injunction or injunction shall have been enacted, entered, promulgated or
enforced by any court or other tribunal or governmental body or authority,
which remains in effect, and prohibits the consummation of the Merger or
otherwise makes it illegal, nor shall any governmental agency have instituted
any action, suit or proceeding which remains pending and which seeks, and which
is reasonably likely, to enjoin, restrain or prohibit the consummation of the
Merger in accordance with the terms of this Agreement.
 
                                      A-40
<PAGE>
 
6.7 Pooling. The letters referred to in Sections 5.10(b) and (c) of this
Agreement shall have been received by SEQUUS and ALZA, respectively.
 
                                  ARTICLE VII
 
                CONDITIONS TO THE OBLIGATIONS OF SEQUUS AND ALZA
 
7.1 Additional Conditions to the Obligation of SEQUUS. The obligation of SEQUUS
to effect the Merger shall be subject to the fulfillment of each of the
following additional conditions, any one or more of which may be waived in
writing by SEQUUS:
 
  (a) The representations and warranties of ALZA and Merger Sub contained in
  this Agreement (without regard to any materiality exceptions or provisions
  therein) shall be true and correct, in all material respects, as of the
  Closing Date, with the same force and effect as if made at the Closing
  Date, except (i) for changes specifically permitted by the terms of this
  Agreement (ii) that the accuracy of the representations and warranties that
  by their terms speak as of the date of this Agreement or some other date
  will be determined as of such date and (iii) where the failure of such
  representations and warranties to be so true and correct does not have an
  ALZA Material Adverse Effect.
 
  (b) ALZA and Merger Sub shall have performed and complied in all material
  respects with all agreements and obligations required by this Agreement to
  be performed or complied with by them on or prior to the Closing Date.
 
  (c) ALZA and Merger Sub shall have furnished a certificate or certificates
  of ALZA and Merger Sub executed on behalf of ALZA and Merger Sub by one or
  more of their respective officers to evidence compliance with the
  conditions set forth in Sections 7.1(a) and (b) of this Agreement.
 
  (d) Each Person identified as an affiliate pursuant to Section 5.11(b)
  shall have executed and delivered an ALZA Affiliate Agreement.
 
  (e) There shall not have occurred, since the date hereof, any ALZA Material
  Adverse Effect.
 
7.2 Additional Conditions to the Obligation of ALZA and Merger Sub. The
obligations of ALZA and Merger Sub to effect the Merger shall be subject to the
fulfillment of each of the following additional conditions, any one or more of
which may be waived in writing by ALZA:
 
  (a) The representations and warranties of SEQUUS contained in this
  Agreement (without regard to any materiality exceptions or provisions
  therein) shall be true and correct, in all material respects, as of the
  Closing Date, with the same force and effect as if made at the Closing
  Date, except (i) for changes specifically permitted by the terms of this
  Agreement, (ii) that the accuracy of the representations and warranties
  that by their terms speak as of the date of this Agreement or some other
  date will be determined as of such date and (iii) where the failure of such
  representations and warranties to be so true and correct does not have a
  SEQUUS Material Adverse Effect.
 
  (b) SEQUUS shall have performed and complied in all material respects with
  all agreements and obligations required by this Agreement to be performed
  or complied with by it on or prior to the Closing Date.
 
                                      A-41
<PAGE>
 
  (c) SEQUUS shall have furnished a certificate of SEQUUS executed on behalf
  of SEQUUS by one of its officers to evidence compliance with the conditions
  set forth in Sections 7.2(a) and (b) of this Agreement.
 
  (d) Each person identified as an Affiliate pursuant to Section 5.11(a)
  shall have executed and delivered a SEQUUS Affiliate Agreement.
 
  (e) There shall not have occurred, since the date hereof, any SEQUUS
  Material Adverse Effect.
 
                                  ARTICLE VIII
 
                                  TERMINATION
 
8.1 Termination. This Agreement may be terminated and the Merger may be
abandoned at any time prior to the Effective Time, whether before or after
approval by the stockholders of SEQUUS:
 
  (a) by mutual written consent of the parties duly authorized by the boards
  of directors of ALZA, SEQUUS and Merger Sub;
 
  (b) by either ALZA or SEQUUS if the Merger shall not have been consummated
  on or before April 1, 1999, which date may be extended by mutual consent of
  the parties hereto; provided, however, that a party shall not be permitted
  to terminate this Agreement pursuant to this Section 8.1(b) if such party
  shall have breached in any material respect its obligations under this
  Agreement in any manner that shall have proximately contributed to the
  failure to consummate the Merger on or before such date;
 
  (c) by either ALZA or SEQUUS if (i) a statute, rule, regulation or
  executive order shall have been enacted, entered or promulgated prohibiting
  the consummation of the Merger substantially on the terms contemplated
  hereby or (ii) a court of competent jurisdiction or other Government Entity
  shall have issued an order, decree, ruling or injunction, or taken any
  other action, having the effect of permanently restraining, enjoining or
  otherwise prohibiting the Merger substantially on the terms contemplated
  hereby, and such order, decree, ruling, injunction or other action shall
  have become final and non-appealable; provided, that a party shall not be
  permitted to terminate this Agreement pursuant to this Section 8.1(c)
  unless such party shall have used its reasonable efforts to remove such
  order, decree, ruling or injunction; or
 
  (d) by either ALZA or SEQUUS if (i) the SEQUUS Special Meeting (and any
  adjournment or postponement thereof) shall have been held and completed and
  SEQUUS' stockholders shall have taken a final vote on the proposal to
  approve and adopt this Agreement and approve the Merger and (ii) the
  requisite approval of SEQUUS' stockholders at such SEQUUS Special Meeting
  or any such adjournment or postponement thereof is not obtained thereat (a
  "SEQUUS Negative Vote"); provided, that a party shall not be permitted to
  terminate this Agreement pursuant to this Section 8.1(d) if such party
  shall have breached in any material respect its obligations under this
  Agreement in any manner that shall have proximately contributed to the
  failure to obtain such stockholder approval.
 
                                      A-42
<PAGE>
 
8.2 Termination by ALZA. This Agreement may be terminated and the Merger may be
abandoned at any time prior to the Effective Time, whether before or after
approval by the stockholders of SEQUUS, by action of the board of directors of
ALZA, if:
 
  (a) SEQUUS shall have failed to comply in any material respect with any of
  the covenants or agreements contained in any Section of this Agreement to
  be complied with or performed by SEQUUS at or prior to such date of
  termination such that the Closing condition set forth in Section 7.2(b)
  would not be satisfied; provided, however, that if such failure or failures
  are capable of being cured prior to the Effective Time such that such
  condition would be satisfied, then ALZA shall not be permitted to terminate
  this Agreement pursuant to this Section 8.2(a) unless ALZA shall have
  delivered to SEQUUS written notice of such failure or failures and such
  failure or failures shall not have been so cured within 30 days after
  delivery to SEQUUS of such written notice; provided, further that ALZA
  shall not be permitted to terminate this Agreement pursuant to this Section
  8.2(a) if ALZA shall have breached in any material respect its obligations
  under this Agreement in any manner that shall have proximately caused such
  failure or failures of SEQUUS;
 
  (b) there exists a breach or breaches of any representation or warranty of
  SEQUUS contained in this Agreement such that the Closing condition set
  forth in Section 7.2(a) would not be satisfied; provided, however, that if
  such breach or breaches are capable of being cured prior to the Effective
  Time such that such condition would be satisfied, then ALZA shall not be
  permitted to terminate this Agreement pursuant to this Section 8.2(b)
  unless ALZA shall have delivered to SEQUUS written notice of such breach or
  breaches and such breach or breaches shall not have been so cured within 30
  days after delivery to SEQUUS of such written notice; provided, further
  that ALZA shall not be permitted to terminate this Agreement pursuant to
  this Section 8.2(b) if ALZA shall have breached in any material respect its
  obligations under this Agreement in any manner that shall have proximately
  caused such breach or breaches of SEQUUS; or
 
  (c) (i) the board of directors of SEQUUS fails to recommend the approval of
  this Agreement to SEQUUS' stockholders, or withdraws, amends or modifies in
  a manner adverse to ALZA its recommendation to SEQUUS' stockholders for
  approval of this Agreement, (ii) a tender offer (to which Rule 14e-2(a)
  applies) for at least 20% of the outstanding shares of capital stock of
  SEQUUS is commenced prior to the SEQUUS Special Meeting, and within the
  time required by Rule 14e-2(a) under the Exchange Act the board of
  directors of SEQUUS fails to recommend against acceptance of such tender
  offer, or takes no position with respect to such tender offer, or states
  its inability to take a position with respect to such tender offer, (iii)
  an Acquisition Proposal is publicly announced and SEQUUS or its board of
  directors takes any position (including stating an inability to make a
  recommendation) with respect to such Acquisition Proposal within 10 days
  after the public announcement of such Acquisition Proposal other than a
  recommendation to reject such Acquisition Proposal, (iv) the board of
  directors of SEQUUS accepts or recommends to the stockholders of SEQUUS a
  Superior Proposal, or (v) the board of directors of SEQUUS resolves to take
  any of the foregoing actions.
 
                                      A-43
<PAGE>
 
8.3 Termination by SEQUUS. This Agreement may be terminated and the Merger may
be abandoned at any time prior to the Effective Time, before or after approval
by the stockholders of SEQUUS, by action of the board of directors of SEQUUS,
if:
 
  (a) ALZA or Merger Sub shall have failed to comply in any material respect
  with any of the covenants or agreements contained in any Section of this
  Agreement to be complied with or performed by ALZA or Merger Sub at or
  prior to such date of termination such that the Closing condition set forth
  in Section 7.1(b) would not be satisfied; provided, however, that if such
  failure or failures are capable of being cured prior to the Effective Time
  such that such condition would be satisfied, then SEQUUS shall not be
  permitted to terminate this Agreement pursuant to this Section 8.3(a)
  unless SEQUUS shall have delivered to ALZA written notice of such failure
  or failures and such failure or failures shall not have been so cured
  within 30 days after such written notice; provided, further, that SEQUUS
  shall not be permitted to terminate this Agreement pursuant to this Section
  8.3(a) if SEQUUS shall have breached in any material respect its
  obligations under this Agreement in any manner that shall have proximately
  caused such failure or failures of ALZA;
 
  (b) there exists a breach or breaches of any representation or warranty of
  ALZA or Merger Sub contained in this Agreement such that the Closing
  condition set forth in Section 7.1(a) would not be satisfied; provided,
  however, that if such breach or breaches are capable of being cured prior
  to the Effective Time such that such condition would be satisfied, then
  SEQUUS shall not be permitted to terminate this Agreement pursuant to this
  Section 8.3(b) unless SEQUUS shall have delivered to ALZA written notice of
  such breach or breaches and such breach or breaches shall not have been so
  cured within 30 days after delivery to ALZA of such written notice;
  provided, further, that SEQUUS shall not be permitted to terminate this
  Agreement pursuant to this Section 8.3(b) if SEQUUS shall have breached in
  any material respect its obligations under this Agreement in any manner
  that shall have proximately caused such breach or breaches of ALZA; or
 
  (c) in accordance with Section 5.2 the board of directors of SEQUUS accepts
  or recommends to the stockholders of SEQUUS a Superior Proposal.
 
8.4 Procedure for Termination. In order to terminate this Agreement pursuant to
this Article VIII, a party shall provide written notice thereof to the other
parties.
 
8.5 Effect of Termination.
 
(a) In the event of termination of this Agreement pursuant to this Article
VIII, no party hereto (or any of its directors or officers) shall have any
liability or further obligation under this Agreement to any other party, except
as provided in this Section 8.5 and except that nothing herein shall relieve
any party from liability for a willful breach of this Agreement.
 
(b) If this Agreement is validly terminated (i) by ALZA pursuant to Section
8.2(c), or (ii) by SEQUUS pursuant to Section 8.3(c), and as of the time of
either such termination there shall not have occurred an ALZA Material Adverse
Effect, then within two business days after such termination SEQUUS shall pay
ALZA a termination fee equal to $25,000,000.
 
                                      A-44
<PAGE>
 
(c) If (i) this Agreement is validly terminated by ALZA or SEQUUS pursuant to
Section 8.1(d) as a result of a SEQUUS Negative Vote, (ii) no payment is
required by Section 8.5(b), (iii) prior to such SEQUUS Negative Vote, there
shall have been publicly announced an Acquisition Proposal which shall not have
been withdrawn, (iv) ALZA shall not have breached in any material respect any
of its obligations under this Agreement in any manner that shall have
proximately contributed to such SEQUUS Negative Vote, (v) within one year after
such valid termination of this Agreement pursuant to Section 8.1(d) as a result
of a SEQUUS Negative Vote, there shall have been consummated a transaction
satisfying the requirements of clause (i), (ii) or (iii) of Section 5.2(c), and
(vi) as of the time of such termination there shall not have occurred an ALZA
Material Adverse Effect, then, within two business days following the
consummation of such transaction, SEQUUS shall pay ALZA a termination fee equal
to $25,000,000.
 
(d) SEQUUS will pay any fee payable under this Section 8.5 by wire transfer of
immediately available funds to an account specified by ALZA.
 
                                   ARTICLE IX
 
                                 MISCELLANEOUS
 
9.1 Amendment and Modification. Subject to applicable law, this Agreement may
be amended, modified or supplemented only by written agreement of ALZA, Merger
Sub and SEQUUS at any time prior to the Effective Time; provided, however, that
after approval of this Agreement by the stockholders of SEQUUS, no such
amendment or modification shall change the amount or form of the consideration
to be received by SEQUUS' stockholders in the Merger.
 
9.2 Waiver of Compliance; Consents. Any failure of ALZA or Merger Sub, on the
one hand, or SEQUUS, on the other hand, to comply with any obligation,
covenant, agreement or condition herein may be waived by SEQUUS (with respect
to any failure by ALZA or Merger Sub) or ALZA or Merger Sub (with respect to
any failure by SEQUUS), respectively, only by a written instrument signed by
the party granting such waiver, but such waiver or failure to insist upon
strict compliance with such obligation, covenant, agreement or condition shall
not operate as a waiver of, or estoppel with respect to, any subsequent or
other failure. Whenever this Agreement requires or permits consent by or on
behalf of any party hereto, such consent shall be given in writing in a manner
consistent with the requirements for a waiver of compliance as set forth in
this Section 9.2.
 
9.3 Survival; Investigations. The respective representations and warranties of
ALZA, Merger Sub and SEQUUS contained herein or in any certificates or other
documents delivered prior to or at the Closing shall not be deemed waived or
otherwise affected by any investigation made by any party hereto and shall not
survive the Effective Time.
 
                                      A-45
<PAGE>
 
9.4 Notices. All notices and other communications hereunder shall be in writing
(except any notice required under the last sentence of Section 5.2(a), which
notice shall be delivered both orally and in writing) and shall be delivered
personally by overnight courier or similar means or sent by facsimile with
written confirmation of receipt, to the parties at the addresses specified
below (or at such other address for a party as shall be specified by like
notice). Any such notice shall be effective upon receipt, if personally
delivered or on the next business day following transmittal if sent by
confirmed facsimile. Notices, including oral notices, shall be delivered as
follows:
 
  (a) if to SEQUUS, to:      SEQUUS Pharmaceuticals, Inc.
                             960 Hamilton Ct.
                             Menlo Park, CA 94025
                             Telephone: (650) 617-3037
                             Facsimile: (605) 617-3001
                             Attention: John P. Richard
 
  with a copy to:            Cooley Godward, LLP
                             Five Palo Alto Square
                             3000 El Camino Real
                             Palo Alto, CA 94306
                             Telephone: (650) 843-5000
                             Facsimile: (650) 857-0663
                             Attention: Richard E. Climan, Esq.
                             Keith A. Flaum, Esq.
 
  if to ALZA, or Merger
  Sub, to:                   ALZA Corporation
                             950 Page Mill Road
                             P.O. Box 10950
                             Palo Alto, CA 94303
                             Telephone: (650) 494-5000
                             Facsimile: (650) 496-8048
                             Attention: Peter D. Staple, Esq.
 
  with a copy to:            Heller Ehrman White & McAuliffe
                             525 University Avenue
                             Palo Alto, California 94301
                             Telephone: (650) 324-7000
                             Facsimile: (650) 324-0638
                             Attention: Sarah A. O'Dowd, Esq.
                             Richard A. Peers, Esq.
 
9.5 Assignment; Third Party Beneficiaries.  Neither this Agreement nor any
right, interest or obligation hereunder shall be assigned by any of the parties
hereto without the prior written consent of the other parties. This Agreement
shall be binding upon and inure to the benefit of the parties hereto and their
respective successors and permitted assigns. This Agreement is not intended to
confer any rights or remedies upon any Person other than the parties hereto
and, with respect only to Section 5.8, the Indemnified Parties.
 
                                      A-46
<PAGE>
 
9.6 Governing Law. This Agreement shall be governed by the laws of the State of
Delaware without reference to principles of conflicts of laws.
 
9.7 Counterparts. This Agreement may be executed in two or more counterparts,
each of which shall be deemed an original, but all of which together shall
constitute one and the same instrument.
 
9.8 Severability. In case any one or more of the provisions contained in this
Agreement should be finally determined to be invalid, illegal or unenforceable
in any respect against a party hereto, it shall be adjusted if possible to
effect the intent of the parties. In any event, the validity, legality and
enforceability of the remaining provisions contained herein shall not in any
way be affected or impaired thereby, and such invalidity, illegality or
unenforceability shall only apply as to such party in the specific jurisdiction
where such final determination shall have been made.
 
9.9 Interpretation. The Article and Section headings contained in this
Agreement are solely for the purpose of reference and shall not in any way
affect the meaning or interpretation of this Agreement. The word "including"
shall be deemed to mean "including without limitation."
 
9.10 Entire Agreement. This Agreement and the Confidentiality Agreements,
including the exhibits hereto and the documents and instruments referred to
herein (including the SEQUUS Disclosure Statement and the ALZA Disclosure
Statement), embody the entire agreement and understanding of the parties hereto
in respect of the subject matter contained herein. There are no
representations, promises, warranties, covenants or undertakings, other than
those expressly set forth or referred to herein and therein.
 
9.11 Definition of "Law". When used in this Agreement "law" refers to any
applicable law (whether civil, criminal or administrative) including, without
limitation, common law, statute, statutory instrument, treaty, regulation,
directive, decision, code, order, decree, injunction, resolution or judgment of
any government, quasi-government, supranational, federal, state or local
government, statutory or regulatory body, court, or agency.
 
9.12 Rules of Construction. Each party to this Agreement has been represented
by counsel during the preparation and execution of this Agreement, and
therefore waives any rule of construction that would construe ambiguities
against the party drafting the agreement.
 
                                      A-47
<PAGE>
 
IN WITNESS WHEREOF, ALZA, Merger Sub and SEQUUS have caused this Agreement to
be signed by their respective duly authorized officers as of the date first
above written.
 
                                          ALZA CORPORATION
 
                                                /s/ Ernest Mario, PH.D.
                                          By: _________________________________
 
                                                Chairman and Chief Executive
                                                          Officer
                                          Title:
 
                                          ARGYLE ACQUISITION CORP.
 
                                                    /s/ Peter Staple
                                          By: _________________________________
 
                                          Title:         President
 
                                          SEQUUS PHARMACEUTICALS, INC.
 
                                              /s/ I. Craig Henderson, M.D.
                                          By: _________________________________
 
                                                Chairman and Chief Executive
                                                          Officer
                                          Title:
 
                                      A-48
<PAGE>
 
                                   EXHIBIT A
 
                             CERTIFICATE OF MERGER
                                    MERGING
                            ARGYLE ACQUISITION CORP.
                                 WITH AND INTO
                               THE COMPANY, INC.
 
    (Pursuant to Section 251 of the General Corporation Law of the State of
                                   Delaware)
 
Argyle Acquisition Corp., a Delaware corporation ("Acquisition Corp.") and
SEQUUS Pharmaceuticals, Inc., a Delaware corporation (the "Company"), DO HEREBY
CERTIFY AS FOLLOWS:
 
FIRST: That Acquisition Corp. was incorporated on October 2, 1998, pursuant to
the Delaware General Corporation Law (the "Delaware Law"), and that the Company
was incorporated on February 13, 1987, pursuant to the Delaware Law.
 
SECOND: That an Agreement and Plan of Merger (the "Merger Agreement"), dated as
of October 4, 1998, among Alza Corporation, a Delaware corporation, Acquisition
Corp. and the Company, setting forth the terms and conditions of the merger of
Acquisition Corp. with and into the Company (the "Merger"), has been approved,
adopted, certified, executed and acknowledged by each of the constituent
corporations in accordance with Section 251 of the Delaware Law.
 
THIRD: That the name of the surviving corporation (the "Surviving Corporation")
shall be "SEQUUS Pharmaceuticals, Inc.".
 
FOURTH: That pursuant to the Merger Agreement, the Certificate of Incorporation
of the Surviving Corporation is amended to read in its entirety as set forth in
Exhibit A hereto.
 
FIFTH: That an executed copy of the Merger Agreement is on file at the
principal place of business of the Surviving Corporation at the following
address:
 
 
SIXTH: That a copy of the Merger Agreement will be furnished by the Surviving
Corporation, on request and without cost, to any stockholder of any constituent
corporation.
 
SEVENTH: That the Merger shall become effective upon the filing of this
Certificate of Merger with the Secretary of State of the State of Delaware.
 
                                      A-49
<PAGE>
 
IN WITNESS WHEREOF, each of Acquisition Corp. and the Company has caused this
Certificate of Merger to be executed in its corporate name this      day of
October, 1998.
 
                                          ARGYLE ACQUISITION CORP.
 
                                          -------------------------------------
                                          By:
                                          Its:
 
                                          SEQUUS PHARMACEUTICALS, INC.
 
                                          -------------------------------------
                                          By:
                                          Its:
 
                                      A-50
<PAGE>
 
                                                                       ANNEX B-1
 
                      FORM OF SEQUUS AFFILIATES AGREEMENT
 
                                                               October    , 1998
 
ALZA Corporation
 
Ladies and Gentlemen:
 
The undersigned has been advised that as of the date hereof the undersigned may
be deemed to be an "affiliate" of Sequus Pharmaceuticals, Inc., a Delaware
corporation ("Sequus"), as the term "affiliate" is (i) defined for purposes of
paragraphs (c) and (d) of Rule 145 of the Rules and Regulations (the "Rules and
Regulations") of the Securities and Exchange Commission (the "Commission")
under the Securities Act of 1933, as amended (the "Act"), and/or (ii) used in
and for purposes of Accounting Series Releases 130 and 135, as amended, of the
Commission, although nothing contained herein shall be construed as an
admission   by the undersigned that the undersigned is in fact an affiliate of
Sequus. Pursuant to the terms of the Agreement and Plan of Merger, dated as of
October ,1998 (the "Agreement"), among ALZA Corporation, a Delaware corporation
("ALZA"), Argyle Acquisition Corp., a Delaware corporation, and Sequus, at the
Effective Time (as defined in the Agreement) Sequus will become a wholly owned
subsidiary of ALZA.
 
As a result of the Merger (as defined in the Agreement), the undersigned may
receive shares of Common Stock, par value $0.01 per share, of ALZA ("ALZA
Common Stock"). The undersigned would receive such shares in exchange for
shares of Common Stock, par value $0.0001 per share, of Sequus owned by the
undersigned.
 
The undersigned and ALZA agree that in the event the undersigned receives any
ALZA Common Stock in the Merger:
 
  (A) The undersigned has carefully read this letter and discussed its
  requirements and other applicable limitations upon the undersigned's
  ability to sell, transfer or otherwise dispose of the ALZA Common Stock
  issued to the undersigned in the Merger, to the extent the undersigned has
  felt it necessary, with the undersigned's counsel.
 
  (B) The undersigned has been advised that the issuance of shares of ALZA
  Common Stock to the undersigned in the Merger will be registered under the
  Act by a Registration Statement on Form S-4. However, the undersigned has
  also been advised that because (i) at the time of the Merger's submission
  for a vote of the stockholders of Sequus the undersigned may be deemed an
  affiliate of Sequus, and (ii) the re-sale or other distribution by the
  undersigned of the ALZA Common Stock received in the Merger has not been
  registered under the Act, the undersigned may not sell, transfer or
  otherwise dispose of ALZA Common Stock issued to the undersigned in the
  Merger unless (a) such sale, transfer or other disposition has been
  registered under the Act, (b) such sale, transfer or other disposition is
  made in conformity with the volume and other
 
                                     B-1-1
<PAGE>
 
  applicable limitations imposed by Rule 145 under the Act, (c) the volume
  and other applicable limitations imposed by Rule 145 under the Act no
  longer apply, or (d) in the opinion of counsel reasonably acceptable to
  ALZA, such sale, transfer or other disposition is otherwise exempt from
  registration under the Act.
 
  (C) The undersigned understands that ALZA will be under no obligation to
  register the sale, transfer or other disposition of the ALZA Common Stock
  by the undersigned or on the undersigned's behalf under the Act or to take
  any other action necessary in order to make compliance with an exemption
  from such registration available. Notwithstanding the foregoing, ALZA shall
  file on a timely basis, from and after the Effective Time (as defined in
  the Agreement) and as long as is necessary in order to permit the
  undersigned to sell ALZA Common Stock held by the undersigned pursuant to
  Rule 145, all reports required to be filed by it pursuant to the Securities
  Exchange Act of 1934, as amended, and shall otherwise make available
  adequate information regarding ALZA in such manner as may be required to
  satisfy the requirements of Rule 144(c) under the Act as now in effect.
 
  (D) The undersigned understands that stop transfer instructions will be
  given to ALZA's transfer agent with respect to the ALZA Common Stock issued
  to the undersigned in the Merger and that there may be placed on the
  certificates for the ALZA Common Stock issued to the undersigned in the
  Merger, or any substitutions therefor, a legend stating in substance:
 
    "THE SHARES REPRESENTED BY THIS CERTIFICATE WERE ISSUED IN A
    TRANSACTION TO WHICH RULE 145 UNDER THE SECURITIES ACT OF 1933, AS
    AMENDED, APPLIES. THE SHARES REPRESENTED BY THIS CERTIFICATE MAY ONLY
    BE TRANSFERRED IN ACCORDANCE WITH THE TERMS OF A LETTER AGREEMENT DATED
              1998, A COPY OF WHICH AGREEMENT IS ON FILE AT THE PRINCIPAL
    OFFICES OF ARGYLE."
 
  (E) The undersigned also understands that unless the transfer by the
  undersigned of ALZA Common Stock issued to the undersigned in the Merger
  (i) has been registered under the Act or (ii) is a sale made in conformity
  with the provisions of this letter, ALZA reserves the right, in its sole
  discretion, to place the following legend on the certificates issued to any
  transferee of shares from the undersigned:
 
    "THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
    UNDER THE SECURITIES ACT OF 1933 AND WERE ACQUIRED FROM A PERSON WHO
    RECEIVED SUCH SHARES IN A TRANSACTION TO WHICH RULE 145 UNDER THE
    SECURITIES ACT OF 1933, AS AMENDED, APPLIES. THE SHARES HAVE BEEN
    ACQUIRED BY THE HOLDER NOT WITH A VIEW TO, OR FOR RESALE IN CONNECTION
    WITH, ANY DISTRIBUTION THEREOF WITHIN THE MEANING OF THE SECURITIES ACT
    OF 1933, AS AMENDED, AND MAY NOT BE OFFERED, SOLD, PLEDGED OR OTHERWISE
    TRANSFERRED EXCEPT IN ACCORDANCE WITH AN EXEMPTION FROM THE
    REGISTRATION REQUIREMENTS OF THE SECURITIES ACT OF 1933, AS AMENDED."
 
                                     B-1-2
<PAGE>
 
It is understood and agreed that the legend set forth in paragraph D or E above
shall be removed by delivery of substitute certificates without such legend if
the undersigned or the undersigned's transferee shall have delivered to ALZA
(i) a copy of a letter from the staff of the Commission, or an opinion of
counsel, in form and substance reasonably satisfactory to ALZA, to the effect
that such legend is not required for purposes of the Act or (ii) reasonably
satisfactory evidence or representations that the shares represented by such
certificates are being or have been transferred in a transaction made in
conformity with the provisions of Rule 145 under the Act, or that the
limitations imposed by Rule 145 under the Act no longer apply.
 
The undersigned agrees that, until after such time as results covering at least
30 days of post-Merger combined operations of ALZA and Sequus have been
published by ALZA within the meaning of Section 201.01 of the Commission's
Codification of Financial Reporting Policies or the termination of the
Agreement, whichever is sooner, the undersigned will not, without the prior
consent of ALZA (which consent shall not be unreasonably withheld or delayed):
(i) within the 30 days prior to the Effective Time (as defined in the
Agreement), sell, transfer or otherwise dispose of, or in any other way reduce
the undersigned's risk of ownership or investment in, or make any offer or
agreement relating to any of the foregoing with respect to any shares of the
Common Stock of Sequus held by the undersigned, except pursuant to and upon
consummation of the Merger (as defined in the Agreement); or (ii) sell,
transfer or otherwise dispose of, or in any other way reduce the undersigned's
risk of ownership or investment in, or make any offer or agreement relating to
any of the foregoing with respect to the ALZA Common Stock received by the
undersigned in the Merger.
 
In the event the Agreement is terminated, this letter agreement shall terminate
and shall cease to be of any force or effect.
 
                                              Very truly yours,
 
Acknowledged this     day of           , 1998.
 
ALZA CORPORATION
 
By:_________________________________
  Name:
 
                                     B-1-3
<PAGE>
 
                                                                       ANNEX B-2
 
                       FORM OF ALZA AFFILIATES AGREEMENT
 
                                October 4, 1998
 
Sequus Pharmaceuticals, Inc.
 
Ladies and Gentlemen:
 
The undersigned has been advised that as of the date hereof the undersigned may
be deemed to be an "affiliate" of ALZA Corporation, a Delaware corporation
("ALZA"), as the term "affiliate" is used in and defined for purposes of
Accounting Series Releases 130 and 135, as amended, of the Securities and
Exchange Commission ("Commission"). Pursuant to the terms of the Agreement and
Plan of Merger, dated as of October 4, 1998 (the "Agreement"), among ALZA,
Argyle Acquisition Corp., a Delaware corporation, and SEQUUS Pharmaceuticals,
Inc., a Delaware corporation ("SEQUUS"), at the Effective Time (as defined in
the Agreement) SEQUUS will become a wholly-owned subsidiary of ALZA.
 
Until after such time as results covering at least 30 days of post-merger
combined operations of ALZA and SEQUUS have been published within the meaning
of Section 201.01 of the Commission's Codification of Financial Reporting
Policies or the termination of the Agreement, whichever is sooner, the
undersigned agrees that the undersigned will not, without the prior consent of
ALZA (which consent shall not be unreasonably withheld or delayed) within the
30 days prior to the Effective Time (as defined in the Agreement), sell,
transfer or otherwise dispose of, or in any other way reduce the undersigned's
risk of ownership or investment in, or make any offer or agreement relating to
any of the foregoing with respect to any shares of the Common Stock of ALZA
held by the undersigned.
 
                                     Very truly yours,
 
                                     ------------------------------------------
                                     Director and/or Officer
 
Acknowledged this     day of           , 1998.
 
SEQUUS PHARMACEUTICALS, INC.
 
By:_________________________________
 
Its:________________________________
 
                                     B-2-1
<PAGE>
 
                  [LETTERHEAD OF CREDIT SUISSE FIRST BOSTON]
 
                                                                        ANNEX C
Board of Directors
c/o SEQUUS Pharmaceuticals, Inc.
960 Hamilton Court
Menlo Park, CA 94025-1430
 
October 4, 1998
 
Dear Sirs and Madams:
 
You have asked us to advise you with respect to the fairness to the
stockholders of SEQUUS Pharmaceuticals, Inc (the "Company") from a financial
point of view of the consideration to be received by such stockholders
pursuant to the terms of the Agreement and Plan of Merger, dated as of October
4, 1998 (the "Acquisition Agreement"), among the Company, Alza Corporation
(the "Acquiror") and Argyle Acquisition Corp. (the "Sub"). The Acquisition
Agreement provides for the Merger (the "Merger") of the Sub with and into the
Company pursuant to which the Company will become a wholly owned subsidiary of
the Acquiror and each outstanding share of Common Stock, par value $.0001 per
share, of the Company (the "Company Common Stock") will be converted into
0.400 (the "Exchange Ratio") shares of Common Stock, par value $.01 per share,
of the Acquiror (the "Acquiror Common Stock").
 
In arriving at our opinion, we have reviewed certain publicly available
business and financial information relating to the Company and the Acquiror,
as well as the Acquisition Agreement. We have also reviewed certain other
information, including financial forecasts, provided to us by the Company and
the Acquiror, and have met with the Company's and the Acquiror's managements
to discuss the business and prospects of the Company and the Acquiror.
 
We have also considered certain financial and stock market data of the Company
and the Acquiror, and we have compared those data with similar data for other
publicly held companies in businesses similar to the Company and the Acquiror
and we have considered the financial terms of certain other business
combinations and other transactions which have recently been effected. We also
considered such other information, financial studies, analyses and
investigations and financial, economic and market criteria which we deemed
relevant.
 
In connection with our review, we have not assumed any responsibility for
independent verification of any of the foregoing information and have relied
on it being complete and accurate in all material respects. With respect to
the financial forecasts, we have assumed that they have been reasonably
prepared on a bases reflecting the best currently available estimates and
judgments of the Company's and the Acquiror's managements as to the future
financial performance of the Company anticipated to result from the Merger. In
addition, we have not been requested to make, and have not made, an
independent evaluation or appraisal of the assets or liabilities (contingent
or otherwise) of the Company or the Acquiror, nor have we been furnished with
any such evaluations or appraisals. Our opinion is necessarily based upon
financial, economic, market and other conditions as they exist and can be
evaluated on the date hereof. We are not expressing any opinion as to the
actual value of the Acquiror Common Stock when issued to the Company's
stockholders pursuant to the Merger or the prices at which the Acquiror Common
Stock will trade subsequent to the Merger. We were not
 
                                      C-1
<PAGE>
 
requested to, and did not, solicit third party indications of interest in
acquiring all or any part of the Company.
 
We have acted as financial advisor to the Company in connection with the Merger
and will receive a fee for our services, a significant portion of which is
contingent upon the consummation of the Merger. We will also receive a fee for
rendering this opinion (to be fully credited against the fee we receive upon
consummation of the transaction). In the past, we have performed certain
investment banking services for the Company.
 
In the ordinary course of our business, we and our affiliates may actively
trade the debt and equity securities of both the Company and the Acquiror for
our and such affiliates' own accounts and for the accounts of customers and,
accordingly may at any time hold a long or short position in such securities.
 
It is understood that this letter is for the information of the Board of
Directors of the Company in connection with its consideration of the Merger,
does not constitute a recommendation to any stockholder as to how such
stockholder should vote on the proposed Merger and is not to be quoted or
referred to, in whole or in part, in any registration statement, prospectus or
proxy statement, or in any other document used in connection with the offering
or sale of securities, nor shall this letter be used for any other purposes,
without our prior written consent.
 
Based upon and subject to the foregoing, it is our opinion that, as of the date
hereof, the Exchange Ratio is fair to holders of Company Common Stock from a
financial point of view.
 
Very Truly Yours,
 
CREDIT SUISSE FIRST BOSTON
 CORPORATION
 
       /s/ Trygve Mikkelsen
By: _________________________________
           Trygve Mikkelsen
           Managing Director
 
                                      C-2
<PAGE>
 
 
 
PROXY
                          SEQUUS PHARMACEUTICALS, INC.
                   Proxy for Special Meeting of Stockholders
 
          THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS
 
  The undersigned hereby appoint(s) I. CRAIG HENDERSON, M.D. and SALLY A.
DAVENPORT, or either of them, each with full power of substitution, as the
lawful attorneys and proxies of the undersigned to vote as designated below,
and in their discretion, upon such other business as may properly be presented
to the meeting, all of the shares of SEQUUS PHARMACEUTICALS, INC. (the
"Company") which the undersigned shall be entitled to vote at the special
meeting of Stockholders on March 16, 1999 at the offices of the Company at 960
Hamilton Court, Menlo Park, California, and at any adjournments or
postponements thereof.
 
  The shares represented by this proxy, will be voted in the manner directed by
the undersigned stockholder. WHEN NO CHOICE IS INDICATED, THIS PROXY WILL BE
VOTED FOR THE PROPOSAL LISTED ON THE REVERSE. This proxy may be revoked at any
time prior to the time it is voted by any means described in the accompanying
proxy statement/prospectus.
 
                 PLEASE COMPLETE, DATE AND SIGN THIS PROXY AND
                  RETURN IT PROMPTLY IN THE ENCLOSED ENVELOPE
 
                              FOLD AND DETACH HERE
 
 
 
 
           THE BOARD RECOMMENDS A VOTE "FOR" THE FOLLOWING PROPOSAL.
 
<TABLE>
 <C>        <S>                                                             <C>
                                                              PLEASE MARK
                                                             YOUR CHOICES
                                                                LIKE THIS   [X]
 Proposal   To approve and adopt the Agreement and Plan of Merger, dated
 1.         as of October 4, 1998, by and among ALZA Corporation, a
            Delaware corporation ("ALZA"), the Company and Argyle
            Acquisition Corp., a Delaware corporation and wholly owned
            subsidiary of ALZA ("Merger Sub"), providing for the merger
            of Merger Sub with and into the Company. As a result of the
            merger, each outstanding share of the common stock, par value
            $.0001 per share, of the Company will be converted into the
            right to receive 0.40 of a share of the common stock, par
            value $.01 per share, of ALZA and the Company will become a
            wholly owned subsidiary of ALZA.
</TABLE>
 
                       [_] FOR  [_] AGAINST  [_] ABSTAIN
 
Signature(s)__________________________________________________ Date       , 1999
 
Please date and sign exactly as name(s) appear(s) hereon. If shares are held
jointly, each holder should sign. Please give full title and capacity in which
signing if not signing as an individual.
 
                              FOLD AND DETACH HERE


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