EXHIBIT 2.3

                              [FORM OF LOCK-UP]

                                                  ______________, 1998

Discovery Laboratories, Inc.
509 Madison Avenue, 14th Floor
New York, New York  10022

Ladies and Gentlemen:

      This letter agreement is in connection with the Agreement and Plan of
Merger dated as of March 5, 1998 (the "Merger Agreement") by and among Discovery
Laboratories, Inc., a Delaware corporation (the "Company"), ATI Acquisition
Corp., a Delaware corporation and a wholly-owned subsidiary of the Company
("Acquisition Sub"), and Acute Therapeutics, Inc., a Delaware corporation
("Acute") pursuant to which, subject to the terms and conditions of the Merger
Agreement, the undersigned may receive securities of the Company (the "Merger
Securities").

      In consideration of the foregoing and in order to induce you to consummate
the merger of Acquisition Sub with and into Acute pursuant to the Merger
Agreement (the "Merger"), the undersigned hereby irrevocably agrees that it will
not on or before November 25, 1998, directly or indirectly, sell, offer,
contract to sell, transfer the economic risk of ownership in, make any short
sale, pledge or otherwise dispose of any shares of the Company's Common Stock,
or any securities convertible into or exchangeable or exercisable for or any
other rights to purchase or acquire the Company's Common Stock, in each case
which are attributable to the Merger Securities, without the prior written
consent of the Company.

      Notwithstanding the foregoing, if the undersigned is an individual, he or
she may transfer any shares of Common Stock or securities convertible into or
exchangeable or exercisable for the Company's Common Stock, in each case which
are attributable to the Merger Securities, either during his or her lifetime or
on death by will or intestacy to his or her immediate family or to a trust the
beneficiaries of which are exclusively the undersigned and/or a member or
members of his or her immediate family; provided, however, that prior to any
such transfer each transferee shall execute an agreement, satisfactory to the
Company, pursuant to which each transferee shall agree to receive and hold such
shares of Common Stock, or securities convertible into or exchangeable or
exercisable for the Common Stock, subject to the provisions hereof, and there
shall be no further transfer except in accordance with the provisions hereof.
For the purposes of this paragraph, "immediate family" shall mean lineal
descendant, father, mother, brother or sister of the transferor.

      The undersigned understands that the agreements of the undersigned are
irrevocable and shall be binding upon the undersigned's heirs, legal
representatives, successors and assigns. The undersigned agrees and consents to
the entry of stop transfer instructions with the Company's transfer agent
against the transfer of the Company's Common Stock or other securities of the
Company received by the undersigned pursuant to the Merger Agreement except in
compliance with this agreement and further agrees that any stock certificates of
the Company, and any other document evidencing ownership of securities of the
Company, issued to the undersigned pursuant to the Merger Agreement shall bear
restrictive legends prohibiting transfers except in accordance with the terms of
this letter.

      This agreement shall be governed by and construed in accordance with the
laws of the State of Delaware as applied to agreements entered into and
performed by Delaware residents and entirely to be performed within Delaware.

                                          Very truly yours,




Dated: _______________                    __________________________
                                          Signature


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                                          Printed Name and Title



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