
<PAGE>

                                                                   EXHIBIT 10.12

             Warrant to Purchase 87,500 Shares of Common Stock or
        such additional shares as this Warrant may entitle the holder
              to purchase pursuant to provisions of this Warrant.


                       WARRANT TO PURCHASE COMMON STOCK

                                      OF

                      3-DIMENSIONAL PHARMACEUTICALS, INC.



          This is to Certify That, FOR VALUE RECEIVED, Sentron Medical, Inc. or
assigns ("Holder") is entitled to purchase, subject to the provisions of this
Warrant, from 3-Dimensional Pharmaceuticals, Inc., a Delaware corporation (the
"Company"), 87,500 fully paid, validly issued and nonassessable shares of Common
Stock, par value $.001 per share, of the Company ("Common Stock") at a price of
$1.25 per share during the Exercise Period (as defined below).  The number of
shares of Common Stock to be received upon the exercise of this Warrant and the
price to be paid for each share of Common Stock may be adjusted from time to
time as hereinafter set forth.  The shares of Common Stock deliverable upon such
exercise, and as adjusted from time to time, are hereinafter sometimes referred
to as "Warrant Shares" and the exercise price of a share of Common Stock in
effect at any time and as adjusted from time to time is hereinafter sometimes
referred to as the "Exercise Price."  This Warrant is being issued in connection
with the issuance by the Company of Warrants to purchase shares of Common Stock
and promissory notes in the aggregate principal amount of up to $10,000,000 (the
"Notes"), pursuant to a Note and Warrant Purchase Agreement dated as of November
18, 1999 (the "Agreement").

1.              EXERCISE OF WARRANT.

        a.           This Warrant may be exercised in whole or in part at any
                time or from time to time on or after November 18, 1999 until 5
                p.m. New York City Time on November 18, 2000 (the "Exercise
                Period"); provided, however, that if such day is a day on which
                banking institutions in the State of New York are authorized by
                law to close, then on the next succeeding day which shall not be
                such a day. This Warrant may be exercised by presentation and
                surrender hereof to the Company at its principal office, or at
                the office of its stock transfer agent, if any, with the
                Purchase Form annexed hereto duly executed and accompanied by
                payment of the Exercise Price for the number of Warrant Shares
                specified
<PAGE>

                in such form. As soon as practicable after each such exercise of
                the Warrants, but not later than seven (7) days from the date of
                such exercise, the Company shall issue and deliver to the Holder
                a certificate or certificates for the Warrant Shares issuable
                upon such exercise, registered in the name of the Holder or its
                designee. If this Warrant should be exercised in part only, the
                Company shall, upon surrender of this Warrant for cancellation,
                execute and deliver a new Warrant evidencing the rights of the
                Holder thereof to purchase the balance of the Warrant Shares
                purchasable thereunder. Upon receipt by the Company of this
                Warrant at its office, or by the stock transfer agent of the
                Company at its office, in proper form for exercise, the Holder
                shall be deemed to be the holder of record of the shares of
                Common Stock issuable upon such exercise, notwithstanding that
                the stock transfer books of the Company shall then be closed or
                that certificates representing such shares of Common Stock shall
                not then be physically delivered to the Holder.

        b.           At any time during the Exercise Period, the Holder may, at
                its option, exchange this Warrant, in whole or in part (a
                "Warrant Exchange") into the number of Warrant Shares determined
                in accordance with this Section (a)(ii), by surrendering this
                Warrant at the principal office of the Company or at the office
                of its stock transfer agent, accompanied by a notice stating
                such Holder's intent to effect such exchange, the number of
                Warrant Shares to be exchanged and the date on which the Holder
                requests that such Warrant Exchange occur (the "Notice of
                Exchange"). The Warrant Exchange shall take place on the date
                specified in the Notice of Exchange or, if later, the date the
                Notice of Exchange is received by the Company (the "Exchange
                Date"). Certificates for the shares issuable upon such Warrant
                Exchange and, if applicable, a new warrant of like tenor
                evidencing the balance of the shares remaining subject to this
                Warrant, shall be issued as of the Exchange Date and delivered
                to the Holder within seven (7) days following the Exchange Date.
                In connection with any Warrant Exchange, this Warrant shall
                represent the right to subscribe for and acquire the number of
                Warrant Shares (rounded to the next highest integer) equal to
                (i) the number of Warrant Shares specified by the Holder in its
                Notice of Exchange (the "Total Number") less (ii) the number of
                Warrant Shares equal to the quotient obtained by dividing (A)
                the product of the Total Number and the existing Exercise Price
                by (B) the Fair Market Value. "Fair Market Value" shall mean:
                (1) if the Common Stock is listed on a National Securities
                Exchange or admitted to unlisted trading privileges on such
                exchange or listed for trading on the NASDAQ system, the average
                of the last reported sale prices of the Common Stock on such
                exchange or system for the twenty (20) business days ending on
                the last business day prior to the date for which the
                determination is being made; or (2) if the
<PAGE>

                Common Stock is not so listed or admitted to unlisted trading
                privileges, the average of the means of the last reported bid
                and asked prices reported by the National Quotation Bureau, Inc.
                for the twenty (20) business days ending on the last business
                day prior to the date for which the determination is being made;
                or (3) if the Common Stock is not so listed or admitted to
                unlisted trading privileges and bid and asked prices are not so
                reported, an amount, not less than book value thereof as at the
                end of the most recent fiscal year of the Company ending prior
                to the Exchange Date, determined in such reasonable manner as
                may be prescribed by the Board of Directors of the Company.

2.              RESERVATION OF SHARES.  The Company shall at all times reserve
        for issuance and/or delivery upon exercise of this Warrant such number
        of shares of its Common Stock as shall be required for issuance and
        delivery upon exercise of the Warrants.

3.              FRACTIONAL SHARES.  No fractional shares or script representing
        fractional shares shall be issued upon the exercise of this Warrant.
        With respect to any fraction of a share called for upon any exercise
        hereof, the Company shall pay to the Holder an amount in cash equal to
        such fraction multiplied by the Fair Market Value of a share.

4.              EXCHANGE, TRANSFER, ASSIGNMENT OR LOSS OF WARRANT.

                (i)    This Warrant is exchangeable, without expense, at the
                option of the Holder, upon presentation and surrender hereof to
                the Company or at the office of its stock transfer agent, if
                any, for other warrants of different denominations entitling the
                holder thereof to purchase in the aggregate the same number of
                shares of Common Stock purchasable hereunder. Subject to the
                restrictions set forth in subparagraph (ii) below, upon
                surrender of this Warrant to the Company at its principal office
                or at the office of its stock transfer agent, if any, with the
                Assignment Form annexed hereto duly executed and funds
                sufficient to pay any transfer tax, the Company shall, without
                charge, execute and deliver a new Warrant in the name of the
                assignee named in such instrument of assignment and this Warrant
                shall promptly be canceled. This Warrant may be divided or
                combined with other warrants which carry the same rights upon
                presentation hereof at the principal office of the Company or at
                the office of its stock transfer agent, if any, together with a
                written notice specifying the names and denominations in which
                new Warrants are to be issued and signed by the Holder hereof.
                The term "Warrant" as used herein includes any Warrants into
                which this Warrant may be divided or exchanged. Upon receipt by
                the Company of evidence satisfactory to it of the loss, theft,
                destruction or mutilation of this Warrant, and (in the case of
                loss, theft or destruction) of
<PAGE>

                reasonably satisfactory indemnification, and upon surrender and
                cancellation of this Warrant, if mutilated, the Company will
                execute and deliver a new Warrant of like tenor and date. Any
                such new Warrant executed and delivered shall constitute an
                additional contractual obligation on the part of the Company,
                whether or not this Warrant so lost, stolen, destroyed, or
                mutilated shall be at any time enforceable by anyone.

                (ii)    This Warrant and the shares of Common Stock issuable
                upon exercise hereof have not been registered under the
                Securities Act of 1933, as amended, or state securities laws by
                reason of an exemption therefrom. The shares of Common Stock
                issuable upon exercise of this Warrant are not transferable
                except as provided in the Agreement and the Stockholders'
                Agreement dated as of January 6, 1998, as amended from time to
                time ("Stockholders' Agreement"). Shares of Common Stock
                issuable upon exercise of this Warrant will bear an appropriate
                legend to this effect. The restrictions contained herein shall
                be binding on any transferee of the Common Stock issuable upon
                exercise of this Warrant and the Company may require any such
                transferee to execute an instrument agreeing in writing to be
                bound by these restrictions as a condition to transfer.

5.              RIGHTS OF THE HOLDER.  The Holder shall not, by virtue hereof,
        be entitled to any rights of a shareholder in the Company, either at law
        or equity, and the rights of the Holder are limited to those expressed
        in the Warrant and are not enforceable against the Company except to the
        extent set forth herein.

6.              ANTI-DILUTION PROVISIONS.  The Exercise Price in effect at any
        time and the number and kind of securities purchasable upon the exercise
        of the Warrants shall be subject to adjustment from time to time upon
        the happening of certain events as follows:

        a.          In case the Company shall (i) declare a dividend or make a
             distribution on its outstanding shares of Common Stock in shares of
             Common Stock, (ii) subdivide or reclassify its outstanding shares
             of Common Stock into a greater number of shares, or (iii) combine
             or reclassify its outstanding shares of Common Stock into a smaller
             number of shares, the Exercise Price in effect at the time of the
             record date for such dividend or distribution or of the effective
             date of such subdivision, combination or reclassification shall be
             adjusted so that it shall equal the price determined by multiplying
             the Exercise Price by a fraction, the denominator of which shall be
             the number of shares of Common Stock outstanding after giving
             effect to such action, and the numerator of which shall be the
             number of shares of Common Stock outstanding immediately
<PAGE>

             prior to such action. Such adjustment shall be made successively
             whenever any event listed above shall occur.

        b.          In case the Company shall fix a record date for the issuance
             of rights or warrants to all holders of its Common Stock entitling
             them to subscribe for or purchase shares of Common Stock (or
             securities convertible into Common Stock) at a price (the
             "Subscription Price") (or having a conversion price per share) less
             than the Exercise Price on the record date mentioned below, the
             Exercise Price shall be adjusted so that the same shall equal the
             price determined by multiplying the Exercise Price in effect
             immediately prior to the date of issuance by a fraction, the
             numerator of which shall be the sum of the number of shares
             outstanding on the record date mentioned below and the number of
             additional shares of Common Stock which the aggregate offering
             price of the total number of shares of Common Stock so offered (or
             the aggregate conversion price of the convertible securities so
             offered) would purchase at the Exercise Price in effect immediately
             prior to the date of such issuance, and the denominator of which
             shall be the sum of the number of shares of Common Stock
             outstanding on the record date mentioned below and the number of
             additional shares of Common Stock offered for subscription or
             purchase (or into which the convertible securities so offered are
             convertible). Such adjustment shall be made successively whenever
             such rights or warrants are issued and shall become effective
             immediately after the record date for the determination of
             shareholders entitled to receive such rights or warrants; and to
             the extent that shares of Common Stock are not delivered (or
             securities convertible into Common Stock are not delivered) after
             the expiration of such rights or warrants the Exercise Price shall
             be readjusted to the Exercise Price which would then be in effect
             had the adjustments made upon the issuance of such rights or
             warrants been made upon the basis of delivery of only the number of
             shares of Common Stock (or securities convertible into Common
             Stock) actually delivered.

        c.          In case the Company shall hereafter distribute to the
             holders of its Common Stock evidences of its indebtedness or assets
             (excluding cash dividends or distributions and dividends or
             distributions referred to in Subsection (i) above) or subscription
             rights or warrants (excluding those referred to in Subsection (ii)
             above), then in each such case the Exercise Price in effect
             thereafter shall be determined by multiplying the Exercise Price in
             effect immediately prior thereto by a fraction, the numerator of
             which shall be the total number of shares of Common Stock
             outstanding multiplied by the Fair Market Value per share of Common
             Stock, less the fair market value (as determined by the Company's
             Board of Directors) of said assets or evidences of indebtedness so
             distributed or of such rights or warrants, and the denominator of
             which shall be the total number of shares
<PAGE>

             of Common Stock outstanding multiplied by the Fair Market Value per
             share of Common Stock. Such adjustment shall be made successively
             whenever such a record date is fixed. Such adjustment shall be made
             whenever any such distribution is made and shall become effective
             immediately after the record date for the determination of
             shareholders entitled to receive such distribution.

        d.          Whenever the Exercise Price payable upon exercise of each
             Warrant is adjusted pursuant to Subsections (i), (ii) or (iii)
             above, the number of Shares purchasable upon exercise of this
             Warrant shall simultaneously be adjusted by multiplying the number
             of Shares initially issuable upon exercise of this Warrant by the
             Exercise Price in effect on the date hereof and dividing the
             product so obtained by the Exercise Price, as adjusted.

        e.          No adjustment in the Exercise Price shall be required unless
             such adjustment would require an increase or decrease of at least
             5% in such price; provided, however, that any adjustments which by
             reason of this Subsection (v) are not required to be made shall be
             carried forward and taken into account in any subsequent adjustment
             required to be made hereunder. All calculations under this Section
             (f) shall be made to the nearest cent or to the nearest one-
             hundredth of a share, as the case may be. Anything in this Section
             (f) to the contrary notwithstanding, the Company shall be entitled,
             but shall not be required, to make such changes in the Exercise
             Price, in addition to those required by this Section (f), as it
             shall determine, in its sole discretion, to be advisable in order
             that any dividend or distribution in shares of Common Stock, or any
             subdivision, reclassification or combination of Common Stock,
             hereafter made by the Company shall not result in any Federal
             Income tax liability to the holders of Common Stock or securities
             convertible into Common Stock (including Warrants).

        f.          Whenever the Exercise Price is adjusted, as herein provided,
             the Company shall promptly but no later than 10 days after any
             request for such an adjustment by the Holder, cause a notice
             setting forth the adjusted Exercise Price and adjusted number of
             Shares issuable upon exercise of each Warrant, and, if requested,
             information describing the transactions giving rise to such
             adjustments, to be mailed to the Holders at their last addresses
             appearing in the Warrant Register, and shall cause a certified copy
             thereof to be mailed to its transfer agent, if any. The Company may
             retain a firm of independent certified public accountants selected
             by the Board of Directors (who may be the regular accountants
             employed by the Company) to make any computation required by this
             Section (f), and a
<PAGE>

             certificate signed by such firm shall be conclusive evidence of the
             correctness of such adjustment.

        g.          In the event that at any time, as a result of an adjustment
             made pursuant to Subsection (i) above, the Holder of this Warrant
             thereafter shall become entitled to receive any shares of the
             Company, other than Common Stock, thereafter the number of such
             other shares so receivable upon exercise of this Warrant shall be
             subject to adjustment from time to time in a manner and on terms as
             nearly equivalent as practicable to the provisions with respect to
             the Common Stock contained in Subsections (i) to (vi), inclusive
             above.

        h.          Irrespective of any adjustments in the Exercise Price or the
             number or kind of shares purchasable upon exercise of this Warrant,
             Warrants theretofore or thereafter issued may continue to express
             the same price and number and kind of shares as are stated in the
             similar Warrants initially issuable pursuant to the Agreement.

7.           OFFICER'S CERTIFICATE.  Whenever the Exercise Price shall be
        adjusted as required by the provisions of the foregoing Section, the
        Company shall forthwith file in the custody of its Secretary or an
        Assistant Secretary at its principal office and with its stock transfer
        agent, if any, an officer's certificate showing the adjusted Exercise
        Price determined as herein provided, setting forth in reasonable detail
        the facts requiring such adjustment, including a statement of the number
        of additional shares of Common Stock, if any, and such other facts as
        shall be necessary to show the reason for and the manner of computing
        such adjustment. Each such officer's certificate shall be made available
        at all reasonable times for inspection by the holder or any holder of a
        Warrant executed and delivered pursuant to Section (a) and the Company
        shall, forthwith after each such adjustment, mail a copy by certified
        mail of such certificate to the Holder or any such holder.

8.           NOTICES TO WARRANT HOLDERS.  So long as this Warrant shall be
        outstanding, (i) if the Company shall pay any dividend or make any
        distribution upon the Common Stock or (ii) if the Company shall offer to
        the Holders of Common Stock for subscription or purchase by them any
        share of any class or any other rights or (iii) if any capital
        reorganization of the Company, reclassification of the capital stock of
        the Company, consolidation or merger of the Company with or into another
        corporation, sale, lease or transfer of all or substantially all of the
        property and assets of the Company to another corporation, or voluntary
        or involuntary dissolution, liquidation or winding up of the Company
        shall be effected, then in any such case, the Company shall cause to be
        mailed by certified mail to the Holder, at least fifteen days prior to
        the date specified in (x) or (y) below, as the case may be, a notice
        containing a brief description of the proposed
<PAGE>

        action and stating the date on which (x) a record is to be taken for the
        purpose of such dividend, distribution or rights, or (y) such
        reclassification, reorganization, consolidation, merger, conveyance,
        lease, dissolution, liquidation or winding up is to take place and the
        date, if any is to be fixed, as of which the Holders of Common Stock or
        other securities shall receive cash or other property deliverable upon
        such reclassification, reorganization, consolidation, merger,
        conveyance, dissolution, liquidation or winding up.

9.           RECLASSIFICATION, REORGANIZATION OR MERGER.  In case of any
        reclassification, capital reorganization or other change of outstanding
        shares of Common Stock of the Company, or in case of any consolidation
        or merger of the Company with or into another corporation (other than a
        merger with a subsidiary in which merger the Company is the continuing
        corporation and which does not result in any reclassification, capital
        reorganization or other change of outstanding shares of Common Stock of
        the class issuable upon exercise of this Warrant) or in case of any
        sale, lease or conveyance to another corporation of the property of the
        Company as an entirety, the Company shall, as a condition precedent to
        such transaction, cause effective provisions to be made so that the
        Holder shall have the right thereafter by exercising this Warrant at any
        time prior to the expiration of the Warrant, to purchase the kind and
        amount of shares of stock and other securities and property receivable
        upon such reclassification, capital reorganization and other change,
        consolidation, merger, sale or conveyance by a holder of the number of
        shares of Common Stock which might have been purchased upon exercise of
        this Warrant immediately prior to such reclassification, change,
        consolidation, merger, sale or conveyance. Any such provision shall
        include provision for adjustments which shall be as nearly equivalent as
        may be practicable to the adjustments provided for in this Warrant. The
        foregoing provisions of this Section (i) shall similarly apply to
        successive reclassifications, capital reorganizations and changes of
        shares of Common Stock and to successive consolidations, mergers, sales
        or conveyances. In the event that in connection with any such capital
        reorganization or reclassification, consolidation, merger, sale or
        conveyance, additional shares of Common Stock shall be issued in
        exchange, conversion, substitution or payment, in whole or in part, for
        a security of the Company other than Common Stock, any such issue shall
        be treated as an issue of Common Stock covered by the provisions of
        Subsection (i) of Section (f)hereof.
<PAGE>

                              3-DIMENSIONAL PHARMACEUTICALS, INC.


                              By /s/ David C. U'Prichard
                                 -------------------------------------
                              Name:  David C. U'Prichard
                              Title:  Chief Executive Officer


[SEAL]


Dated:  November 18, 1999

Attest:

/s/ Scott M. Horvitz
-----------------------------
Secretary
<PAGE>

                                 PURCHASE FORM
                                 -------------

                                                      Dated _____________, ____

     The undersigned hereby irrevocably elects to exercise the within Warrant to
the extent of purchasing _________ shares of Common Stock and hereby makes
payment of in payment of the actual exercise price thereof

                                   ---------

                    INSTRUCTIONS FOR REGISTRATION OF STOCK
                    --------------------------------------


Name ____________________________________________
     (Please typewrite or print in block letters)

Address  _________________________________


Signature  ________________________________


                                   ---------

                                ASSIGNMENT FORM
                                ---------------

     FOR VALUE RECEIVED, __________________________ hereby sells, assigns and
transfers unto

Name _____________________________________________________
     (Please typewrite or print in block letters)

Address  __________________________________________________
the right to purchase Common Stock represented by this Warrant to the extent of
_____ shares as to which such right is exercisable and does hereby irrevocably
constitute and appoint ____________________ Attorney, to transfer the same on
the books of the Company with full power of substitution in the premises.

Date _____________, _____

Signature ____________________________
