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                    CERTIFICATE OF DESIGNATION, PREFERENCES
                         AND RIGHTS OF SERIES A JUNIOR
                         PARTICIPATING PREFERRED STOCK

                                       of

                               ADOLOR CORPORATION


             Pursuant to Section 151 of the General Corporation Law
                            of the State of Delaware


          The undersigned officer of Adolor Corporation, a corporation organized
and existing under the General Corporation Law of the State of Delaware (the
"Corporation"), in accordance with the provisions of Section 103 thereof, DOES
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HEREBY CERTIFY:

          That pursuant to the authority conferred upon the Board of Directors
by the Certificate of Incorporation, as amended, of the Corporation (the
"Restated Certificate of Incorporation"), the Board of Directors of the
--------------------------------------
Corporation on February 20, 2001 adopted the following resolution creating a
series of 35,000 shares of Preferred Stock designated as Series A Junior
Participating Preferred Stock:

          RESOLVED, that pursuant to the authority vested in the Board of
Directors of this Corporation in accordance with the provisions of its Restated
Certificate of Incorporation, a series of Preferred Stock of the Corporation be
and it hereby is created, and that the designation and amount thereof and the
voting powers, preferences and relative, participating, optional and other
special rights of the shares of such series, and the qualifications, limitations
or restrictions thereof are as follows:

I.    Designation and Amount.  The shares of such series shall be designated as
      ----------------------
"Series A Junior Participating Preferred Stock" and the number of shares
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constituting such series shall be 35,000.

II.   Dividends and Distributions.
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               a.   Subject to the prior and superior rights of the holders of
any shares of any series of Preferred Stock ranking prior and superior to the
shares of Series A Junior Participating Preferred Stock with respect to
dividends, if any, the holders of shares of Series A Junior Participating
Preferred Stock shall be entitled to receive, when, as and if declared by the
Board of Directors out of funds legally available for the purpose, quarterly
dividends payable in cash on the last day of March, June, September and December
in each year (each such date being referred to herein as a "Quarterly Dividend
                                                            ------------------
Payment Date"), commencing on the first Quarterly
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Dividend Payment Date after the first issuance of a share or fraction of a share
of Series A Junior Participating Preferred Stock, in an amount per share
(rounded to the nearest cent) equal to the greater of (a) $100 or (b) subject to
the provision for adjustment hereinafter set forth, 10,000 times the aggregate
per share amount of all cash dividends, and 10,000 times the aggregate per share
amount (payable in kind) of all non-cash dividends or other distributions other
than a dividend payable in shares of Common Stock, par value $.0001 per share,
of the Corporation (the "Common Stock") or a subdivision of the outstanding
                         ------------
shares of Common Stock (by reclassification or otherwise), declared on the
Common Stock since the immediately preceding Quarterly Dividend Payment Date,
or, with respect to the first Quarterly Dividend Payment Date, since the first
issuance of any share or fraction of a share of Series A Junior Participating
Preferred Stock. In the event the Corporation shall at any time after February
20, 2001 (the "Rights Declaration Date") (i) declare any dividend on Common
               -----------------------
Stock payable in shares of Common Stock, (ii) subdivide the outstanding Common
Stock, or (iii) combine the outstanding Common Stock into a smaller number of
shares, then in each such case the amount to which holders of shares of Series A
Junior Participating Preferred Stock were entitled immediately prior to such
event under clause (b) of the preceding sentence shall be adjusted by
multiplying such amount by a fraction the numerator of which is the number of
shares of Common Stock outstanding immediately after such event and the
denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

               b.   The Corporation shall declare a dividend or distribution on
the Series A Junior Participating Preferred Stock as provided in Paragraph (A)
above immediately after it declares a dividend or distribution on the Common
Stock (other than a dividend payable in shares of Common Stock); provided,
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however, that, in the event no dividend or distribution shall have been declared
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on the Common Stock during the period between any Quarterly Dividend Payment
Date and the next subsequent Quarterly Dividend Payment Date, a dividend of $100
per share on the Series A Junior Participating Preferred Stock shall
nevertheless be payable on such subsequent Quarterly Dividend Payment Date.

               c.   Dividends shall begin to accrue and be cumulative on
outstanding shares of Series A Junior Participating Preferred Stock from the
Quarterly Dividend Payment Date next preceding the date of issue of such shares
of Series A Junior Participating Preferred Stock, unless the date of issue of
such shares is prior to the record date for the first Quarterly Dividend Payment
Date, in which case dividends on such shares shall begin to accrue from the date
of issue of such shares, or unless the date of issue is a Quarterly Dividend
Payment Date or is a date after the record date for the determination of holders
of shares of Series A Junior Participating Preferred Stock entitled to receive a
quarterly dividend and before such Quarterly Dividend Payment Date, in either of
which events such dividends shall begin to accrue and be cumulative from such
Quarterly Dividend Payment Date. Accrued but unpaid dividends shall not bear
interest. Dividends paid on the shares of Series A Junior Participating
Preferred Stock in an amount less than the total amount of such dividends at the
time accrued and payable on such shares shall be allocated pro rata on a share-
by-share basis among all such shares at the time outstanding. The Board of
Directors may fix a record date for the determination of holders of shares of
Series A Junior Participating Preferred Stock entitled to receive payment of a
dividend

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or distribution declared thereon, which record date shall be no more than thirty
(30) days prior to the date fixed for the payment thereof.

III.   Voting Rights. The holders of shares of Series A Junior Participating
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Preferred Stock shall have the following voting rights:

                    a.   Subject to the provision for adjustment hereinafter
set forth, each share of Series A Junior Participating Preferred Stock shall
entitle the holder thereof to 10,000 votes on all matters submitted to a vote of
the shareholders of the Corporation. In the event the Corporation shall at any
time after the Rights Declaration Date (i) declare any dividend on Common Stock
payable in shares of Common Stock, (ii) subdivide the outstanding Common Stock,
or (iii) combine the outstanding Common Stock into a smaller number of shares,
then in each such case the number of votes per share to which holders of shares
of Series A Junior Participating Preferred Stock were entitled immediately prior
to such event shall be adjusted by multiplying such number by a fraction the
numerator of which is the number of shares of Common Stock outstanding
immediately after such event and the denominator of which is the number of
shares of Common Stock that were outstanding immediately prior to such event.

                    b.   Except as otherwise provided herein or by law, the
holders of shares of Series A Junior Participating Preferred Stock and the
holders of shares of Common Stock shall vote together as one class on all
matters submitted to a vote of shareholders of the Corporation.

                    c.   Except as set forth herein, holders of Series A Junior
Participating Preferred Stock shall have no special voting rights and their
consent shall not be required (except to the extent they are entitled to vote
with holders of Common Stock as set forth herein) for taking any corporate
action.

IV.    Certain Restrictions.
       --------------------

                    a.   Whenever quarterly dividends or other dividends or
distributions payable on the Series A Junior Participating Preferred Stock as
provided in Section 2 are in arrears, thereafter and until all accrued and
unpaid dividends and distributions, whether or not declared, on shares of Series
A Junior Participating Preferred Stock outstanding shall have been paid in full,
the Corporation shall not:

                         (1)  declare or pay dividends on, make any other
distributions on, or redeem or purchase or otherwise acquire for consideration
any shares of stock ranking junior (either as to dividends or upon liquidation,
dissolution or winding up) to the Series A Junior Participating Preferred Stock;

                         (2)  declare or pay dividends on or make any other
distributions on any shares of stock ranking on a parity (either as to dividends
or upon liquidation, dissolution or winding up) with the Series A Junior
Participating Preferred Stock, except dividends paid ratably on the Series A
Junior Participating Preferred Stock and all such parity stock on which

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dividends are payable or in arrears in proportion to the total amounts to which
the holders of all such shares are then entitled;

                    (3)  redeem or purchase or otherwise acquire for
consideration shares of any stock ranking on a parity (either as to dividends or
upon liquidation, dissolution or winding up) with the Series A Junior
Participating Preferred Stock, provided that the Corporation may at any time
redeem, purchase or otherwise acquire shares of any such parity stock in
exchange for shares of any stock of the Corporation ranking junior (either as to
dividends or upon dissolution, liquidation or winding up) to the Series A Junior
Participating Preferred Stock; or

                    (4)  purchase or otherwise acquire for consideration any
shares of Series A Junior Participating Preferred Stock, or any shares of stock
ranking on a parity with the Series A Junior Participating Preferred Stock,
except in accordance with a purchase offer made in writing or by publication (as
determined by the Board of Directors) to all holders of such shares upon such
terms as the Board of Directors, after consideration of the respective annual
dividend rates and other relative rights and preferences of the respective
series and classes, shall determine in good faith will result in fair and
equitable treatment among the respective series or classes.

               b.   The Corporation shall not permit any subsidiary of the
Corporation to purchase or otherwise acquire for consideration any shares of
stock of the Corporation unless the Corporation could, under Paragraph (A) of
this Section 4, purchase or otherwise acquire such shares at such time and in
such manner.

V.    Reacquired Shares.  Any shares of Series A Junior Participating Preferred
      -----------------
Stock purchased or otherwise acquired by the Corporation in any manner
whatsoever shall be retired and cancelled promptly after the acquisition
thereof.  All such shares shall upon their cancellation become authorized but
unissued shares of Preferred Stock and may be reissued as part of a new series
of Preferred Stock to be created by resolution or resolutions of the Board of
Directors, subject to the conditions and restrictions on issuance set forth
herein.

VI.   Liquidation, Dissolution or Winding Up.  (A) Upon any liquidation
      --------------------------------------
(voluntary or otherwise), dissolution or winding up of the Corporation, no
distribution shall be made to the holders of shares of stock ranking junior
(either as to dividends or upon liquidation, dissolution or winding up) to the
Series A Junior Participating Preferred Stock unless, prior thereto, the holders
of shares of Series A Junior Participating Preferred Stock shall have received
an amount equal to $100 per share of Series A Participating Preferred Stock,
plus an amount equal to accrued and unpaid dividends and distributions thereon,
whether or not declared, to the date of such payment (the "Series A Liquidation
                                                           --------------------
Preference").  Following the payment of the full amount of the Series A
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Liquidation Preference, no additional distributions shall be made to the holders
of shares of Series A Junior Participating Preferred Stock unless, prior
thereto, the holders of shares of Common Stock shall have received an amount per
share (the "Common Adjustment") equal to the quotient obtained by dividing (i)
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the Series A Liquidation Preference by (ii) 100 (as appropriately adjusted as
set forth in subparagraph (C) below to reflect such

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events as stock splits, stock dividends and recapitalizations with respect to
the Common Stock) (such number in clause (ii), the "Adjustment Number").
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Following the payment of the full amount of the Series A Liquidation Preference
and the Common Adjustment in respect of all outstanding shares of Series A
Junior Participating Preferred Stock and Common Stock, respectively, holders of
Series A Junior Participating Preferred Stock and holders of shares of Common
Stock shall receive their ratable and proportionate share of the remaining
assets to be distributed in the ratio of the Adjustment Number to 1 with respect
to such Preferred Stock and Common Stock, on a per share basis, respectively.

               b.   In the event, however, that there are not sufficient assets
available to permit payment in full of the Series A Liquidation Preference and
the liquidation preferences of all other series of preferred stock, if any,
which rank on a parity with the Series A Junior Participating Preferred Stock,
then such remaining assets shall be distributed ratably to the holders of such
parity shares in proportion to their respective liquidation preferences.  In the
event, however, that there are not sufficient assets available to permit payment
in full of the Common Adjustment, then such remaining assets shall be
distributed ratably to the holders of Common Stock.

               c.   In the event the Corporation shall at any time after the
Rights Declaration Date (i) declare any dividend on Common Stock payable in
shares of Common Stock, (ii) subdivide the outstanding Common Stock, or (iii)
combine the outstanding Common Stock into a smaller number of shares, then in
each such case the Adjustment Number in effect immediately prior to such event
shall be adjusted by multiplying such Adjustment Number by a fraction the
numerator of which is the number of shares of Common Stock outstanding
immediately after such event and the denominator of which is the number of
shares of Common Stock that were outstanding immediately prior to such event.

VII.    Consolidation, Merger, etc.  In case the Corporation shall enter into
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any consolidation, merger, combination or other transaction in which the shares
of Common Stock are exchanged for or changed into other stock or securities,
cash and/or any other property, then in any such case the shares of Series A
Junior Participating Preferred Stock shall at the same time be similarly
exchanged or changed in an amount per share (subject to the provision for
adjustment hereinafter set forth) equal to 10,000 times the aggregate amount of
stock, securities, cash and/or any other property (payable in kind), as the case
may be, into which or for which each share of Common Stock is changed or
exchanged.  In the event the Corporation shall at any time after the Rights
Declaration Date (i) declare any dividend on Common Stock payable in shares of
Common Stock, (ii) subdivide the outstanding Common Stock, or (iii) combine the
outstanding Common Stock into a smaller number of shares, then in each such case
the amount set forth in the preceding sentence with respect to the exchange or
change of shares of Series A Junior Participating Preferred Stock shall be
adjusted by multiplying such amount by a fraction the numerator of which is the
number of shares of Common Stock outstanding immediately after such event and
the denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

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VIII.   No Redemption. The shares of Series A Junior Participating Preferred
        -------------
Stock shall not be redeemable.

IX.     Amendment. At any time when any shares of Series A Junior Participating
        ---------
Preferred Stock are outstanding, the Restated Certificate of Incorporation of
the Corporation shall not be further amended in any manner which would
materially alter or change the powers, preferences or special rights of the
Series A Junior Participating Preferred Stock so as to affect them adversely
without the affirmative vote of the holders of a majority or more of the
outstanding shares of Series A Junior Participating Preferred Stock, voting
separately as a class.

X.      Fractional Shares.  Series A Junior Participating Preferred Stock may be
        -----------------
issued in fractions of a share which shall entitle the holder, in proportion to
such holder's fractional shares, to exercise voting rights, receive dividends,
participate in distributions and to have the benefit of all other rights of
holders of Series A Junior Participating Preferred Stock.

            IN WITNESS WHEREOF, we have executed and subscribed this Certificate
and do affirm the foregoing as true under the penalties of perjury this 20th day
of February, 2001.

                              ADOLOR CORPORATION

                              By: ________________________________________
                                 Name:  John J. Farrar
                                 Title: President and Chief Executive Officer

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