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EXHIBIT 4
Endo Pharmaceuticals Inc.
223 Wilmington West Chester Pike
Chadds Ford, Pennsylvania 19317
November 26, 1999
Algos Pharmaceutical Corporation
1333 Campus Parkway
Neptune, New Jersey 07753
Dear Sirs:
In connection with that Agreement and Plan of Merger (the "Merger
Agreement"), dated of even date herewith, by and among Endo Pharmaceuticals
Holdings Inc. ("Holdings"), Endo Inc. and [Target] Pharmaceutical Corporation,
each of the undersigned (collectively, the "Executives") hereby agrees to
consent to (a) the termination of the Holdings' 1997 Executive Stock Option
Plan, (b) the institution of a stock option plan of a newly formed limited
liability company (the "LLC") pursuant to which each of the Executive's stock
options will be exercisable only into shares of common stock of Holdings that is
owned by the LLC, (c) the conversion of each of the Executive's outstanding
options under Holdings' 1997 Executive Stock Option Plan into options under the
stock option plan of the LLC and (d) the terms (including, but not limited to,
the vesting schedule thereto) of such converted options under the stock option
plan of the LLC are to be agreed upon by the Executives and the LLC. Each of the
Executives hereby agrees and acknowledges that from and after the closing of the
transaction contemplated by the Merger Agreement, the Executive's only recourse
upon exercise of such Executive's stock options will be against the LLC and not
against Holdings.
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Algos Pharmaceutical Corporation
November __, 1999
Page 2
If the foregoing correctly sets forth our agreement, please so
indicate by signing a counterpart of this letter whereupon it shall become a
binding agreement between us.
Very truly yours,
/s/ CAROL A. AMMON
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Carol A. Ammon
/s/ MARIANN T. MACDONALD
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Mariann T. MacDonald
/s/ LOUIS J. VOLLMER
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Louis J. Vollmer
/s/ JEFFREY R. BLACK
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Jeffrey R. Black
/s/ OSAGIE O. IMASOGIE
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Osagie O. Imasogie
/s/ DAVID A. LEE
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David A. Lee
