Exhibit 4.2
                                   -----------


                   Schedule of Holders of Unit Purchase Option

     The following individuals and entities are holders of Unit Purchase Options
with respect to an aggregate of 24.06875 units.

Aries Domestic Fund, L.P.
The Aries Trust
Evan S. Borak
Joseph Edelman
Lauren S. Fischer
Marc Florin
Hawkins Group, LLC
Joseph Stevens & Co.
Scott A. Katzmann
John Knox
Donna F. Lozito
Jeff Levine
Tim McInerney
Kirkland Messina
Lindsay A. Rosenwald, M.D.
Wayne L. Rubin
Karl Ruggeberg
Richard Strassman
David Walner
Michael S. Weiss


<PAGE>

THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE BEEN ACQUIRED FOR INVESTMENT
AND NEITHER SUCH SECURITIES NOR THE SECURITIES ISSUABLE UPON EXERCISE HEREOF NOR
THE SECURITIES ISSUABLE UPON EXERCISE THEREOF HAVE BEEN REGISTERED UNDER THE
SECURITIES ACT OF 1933, AS AMENDED OR ANY STATE SECURITIES LAW. SUCH SECURITIES
MAY NOT BE SOLD OR TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR UNLESS
SUCH SALE OR TRANSFER IS EXEMPT FROM THE REGISTRATION AND PROSPECTUS DELIVERY
REQUIREMENTS OF SAID ACT.



                                  PROCEPT, INC.
                                  -------------

          Unit Purchase Option for the Purchase of Units Consisting of
                       Shares of Common Stock and Warrants

No. [ ]                                                    [      ] Option Units


                      FOR VALUE RECEIVED, Procept, Inc., a Delaware corporation
(the "Company"), hereby certifies that [ ], or its assigns, is entitled to
purchase from the Company, at any time or from time to time commencing on
October 9, 1998 and prior to 5:00 P.M., New York City time, on October 9, 2003,
up to [ ] Units, each Unit consisting of (a) the number of shares (rounded to
the nearest whole share with 0.5 of one share being rounded upward) (the
"Offering Quantity") of Common Stock of the Company, par value $.01 per share,
(the "Common Stock") determined by dividing 100,000 by the lesser of (i) $0.50
and (ii) 75% of the Trading Price (as defined in the Subscription Agreement as
hereinafter defined) as of (x) the initial closing date (the "Initial Closing
Date", (y) any interim closing date (each an "Interim Closing Date") or (z) the
final closing date (the "Final Closing Date") of the Offering (as defined below)
whichever is lowest (the "Offering Price"), and (b) warrants (the "Class C
Warrants") to purchase, at an exercise price per share equal to the Offering
Price, at any time prior to the fifth anniversary of the Final Closing Date (as
defined herein) a number of shares of Common Stock equal to the Offering
Quantity, for an aggregate Unit purchase price of [ ] (computed on the basis of
$110,000 per Unit). (Hereinafter, (i) said Units are referred to as the "Units",
(ii) said Class C Warrants are referred to as the "Warrants", (iii) the Common
Stock included in the Units and purchasable upon exercise of the Warrants, is
referred to as the "Common Stock", (iv) the shares of the Common Stock
purchasable hereunder or under any other Option (as hereinafter defined) (or the
shares of any capital stock purchasable hereunder or under any other Option in
lieu of Common Stock) are referred to as the "Common Shares", (v) the shares of
Common Stock purchasable upon exercise of the Warrants hereunder or under any
other Option (as hereinafter defined) are referred to as the "Warrant Shares",
(vi) the aggregate purchase price payable for the Units hereunder is referred to
as the "Aggregate Option Price", (vii) the price payable (initially $110,000 per
Unit, subject to adjustment) for each of the Units, hereunder is referred to as
the "Per Unit Price", (viii) this Option, all similar Options issued on the date
hereof and all warrants hereafter issued in exchange or substitution for this
Option or such similar Options are referred to as the "Options" and (ix) the
holder of this Option is referred to as the "Holder" and the holder of this
Option and all other Options are referred to as the "Holders" and Holders of
more than fifty percent (50%) of the outstanding Options are



<PAGE>



referred to as the "Majority of the Holders." The Aggregate Option Price is not
subject to adjustment. The Per Unit Price is subject to adjustment as
hereinafter provided; in the event of any such adjustment, the number of Common
Shares or Warrant Shares, as the case may be, deliverable upon exercise of this
Option shall be adjusted in accordance with paragraph 3(i) below.

                      This Option, together with options of like tenor,
constituting in the aggregate Options to purchase 9.6275 Units, was originally
issued pursuant to an agency agreement between the Company and Paramount
Capital, Inc., as placement agent (the "Placement Agent") in connection with a
private placement (the "Offering") of 96.275 Units (the "Offering Units"), each
Offering Unit consisting of Common Stock (the "Offering Common") and Class C
Warrants (the "Offering Warrants") for which the Placement Agent acted as
Placement Agent.

                      1. Exercise of Option.

                      (a) This Option may be exercised, in whole at any time or
in part from time to time, commencing on October 9, 1998 and prior to 5:00 P.M.,
New York City time, on October 9, 2003 by the Holder:

                      (i) by the surrender of this Option (with the subscription
              form at the end hereof duly executed) at the address set forth in
              Subsection 10(a) hereof, together with proper payment of the
              Aggregate Option Price, or the proportionate part thereof if this
              Option is exercised in part, with payment for the number of Units
              made by certified or official bank check payable to the order of
              the Company; or

                      (ii) by the surrender of this Option (with the cashless
              exercise form at the end hereof duly executed) (a "Cashless
              Exercise") at the address set forth in Subsec tion 10(a) hereof.
              The exchange of the Option shall take place on the date specified
              in the Cashless Exercise Form or, if later, the date the Cashless
              Exercise Form is surrendered to the Company (the "Exchange Date").
              Such presentation and surrender shall be deemed a waiver of the
              Holder's obligation to pay the Aggregate Option Price, or the
              proportionate part thereof if this Option is exercised in part. In
              the event of a Cashless Exercise this Option shall represent the
              right to subscribe for and acquire the number of Units (rounded to
              the next highest integer) equal to (x) the number of Units
              specified by the Holder in its Cashless Exercise Form (the "Total
              Number") (such number not to exceed the maximum number of Units
              subject to this Option, as may be adjusted from time to time) less
              (y) the number of Units equal to the quotient obtained by dividing
              (A) the product of the Total Number and the existing Per Unit
              Price by (B) the Market Price Per Unit. "Market Price Per Unit"
              shall mean first, if there is a trading market as indicated in
              Subsection (A) below for the Units, such Market Price Per Unit and
              if there is no such trading market in the Units, then Market Price
              Per Unit shall equal the sum of the aggregate Market Price of all
              shares of Common Stock (on per share basis, the "Market Price Per
              Share of Common Stock") and Warrants (on a per warrant basis, the
              "Market Price Per Warrant") which comprise a Unit, with the
              meanings indicated in Subsections (B) through (G) below:



                                      -2-

<PAGE>

                               (A) If the Units are listed on a national
                      securities exchange or listed or admitted to unlisted
                      trading privileges on such exchange or listed for trading
                      on the Nasdaq National Market or the Nasdaq Smallcap
                      Market, the Market Price Per Unit shall be the last
                      reported sale price (or if no last sale, the last
                      quoted ask price) of the Units on such exchange or market
                      for the trading day immediately preceding the Exchange
                      Date; or

                               (B) If the Common Stock or Warrants, as the case
                      may be, are listed on a national securities exchange or
                      admitted to unlisted trading privileges on such exchange
                      or listed for trading on the Nasdaq National Market or the
                      Nasdaq Smallcap Market, the Market Price Per Share of
                      Common Stock, or Market Price Per Warrant, respectively,
                      shall be the last reported sale price (or if no last sale,
                      the last quoted ask price) of the Common Stock or
                      Warrants, respectively, on such exchange or market for the
                      trading day immediately preceding the Exchange Date; or

                               (C) If the Common Stock or Warrants, as the case
                      may be, are not so listed or admitted to unlisted trading
                      privileges, the Market Price Per Share of Common Stock, or
                      Market Price Per Warrant, respectively, shall be the last
                      reported sale price (or if no last sale, the last quoted
                      ask price) of the Common Stock or Warrants in the
                      over-the-counter market as reported by the National
                      Quotation Bureau or similar organization or in the Pink
                      Sheets for the trading day immediately preceding the
                      Exchange Date; or

                               (D) If the Common Stock is not so listed or
                      admitted to unlisted trading privileges and the sale price
                      is (or if no last sale, the last quoted ask price) not so
                      reported, the Market Price Per Share of Common Stock shall
                      be the fair market value as determined by agreement
                      between the Board of Directors of the Company and a
                      Majority of the Holders; or

                               (E) If neither clause (B) nor (C) applies to the
                      Warrants, then the Market Price Per Warrant shall be an
                      amount equal to the difference between (i) the Market
                      Price Per Share of Common Stock which may be received upon
                      the exercise of the Warrants, as determined in paragraphs
                      (B), (C) and (D) above, and (ii) the per share exercise
                      price of the Warrants then in effect.

                               (F) If the Company and the Majority of the
                      Holders are unable to reach agreement on any valuation
                      matter, such valuation shall be submitted to and
                      determined by a nationally recognized independent
                      investment bank selected by the Board of Directors of the
                      Company and the Majority of the Holders (or, if such
                      selection cannot be agreed upon promptly, or in any event
                      within ten days, then such valuation shall be made by a
                      nationally recognized independent investment banking firm
                      selected by the American Arbitration Association in New
                      York City in accordance with its rules), the costs of
                      which valuation shall be paid for by the Company.

                      (iii) by the surrender of this Option (with the
              subscription (promissory note) form at the end hereof duly
              executed) at the address set forth in Subsection 10(a) hereof,
              together with the presentation of a promissory note made payable
              to the Company, duly executed and in the form at the end hereof.
              Such promissory note shall be secured by the securities underlying
              this Option, which shall be held in safe-keeping by the Company as
              collateral for such indebtedness.



                                       -3-


<PAGE>



                      (b) If this Option is exercised in part, the Holder is
entitled to receive a new Option covering the Units, which have not been
exercised and setting forth the proportionate part of the Aggregate Option Price
applicable to such Units. Upon surrender of this Option, the Company will (i)
issue a certificate or certificates in the name of the Holder for the largest
number of whole shares of the Common Stock and Warrants to which the Holder
shall be entitled and, if this Option is exercised in whole, in lieu of any
fractional shares of the Common Stock or Warrants to which the Holder shall be
entitled, pay to the Holder cash in an amount equal to the fair value of such
fractional shares (determined in such reasonable manner as the Board of
Directors of the Company shall determine), and (ii) deliver the other securities
and properties receivable upon the exercise of this Option, or the proportionate
part thereof if this Option is exercised in part, pursuant to the provisions of
this Option; provided, however that if this Option is exercised pursuant to
paragraph 1(a)(iii), the Company will issue but shall not deliver such shares
until such time as the promissory note and all accrued interest thereon shall
have been paid in full, and will hold such shares in safekeeping.

                      (c) This Option shall be exercisable only for Units
consisting of Warrants and Common Shares at the then applicable Per Unit Price
(including any adjustment pursuant to Section 3 below).

                      2. Reservation of Warrant Shares and Common Shares;
Listing. The Company agrees that, prior to the expiration of this Option, the
Company will at all times (a) have authorized and in reserve, and will keep
available, solely for issuance and delivery upon the exercise of this Option,
the Units, the Warrants and the Common Shares underlying such Units and other
securities and properties as from time to time shall be receivable upon the
exercise of this Option, free and clear of all restrictions on sale or transfer,
other than under Federal or state securities laws, and free and clear of all
preemptive rights and rights of first refusal and (b) have authorized and in
reserve, and will keep available, solely for issuance or delivery upon exercise
of the Warrants, the shares of Common Stock, the Warrant Shares and the Common
Shares and other securities and properties as from time to time shall be
receivable upon such exercise, free and clear of all restrictions on sale or
transfer, other than under Federal or state securities laws, and free and clear
of all preemptive rights and rights of first refusal; and (c) if the Company is
listed or hereafter lists its Common Stock on any national securities exchange,
the Nasdaq National Market or the Nasdaq Smallcap Market, use its best efforts
to keep the Common Shares authorized for listing on such exchange upon notice of
issuance.

                      3. Protection Against Dilution.

                      (a) The anti-dilution provisions of the Warrant Agreement
shall protect the Holder from dilution of the purchase rights represented by the
Warrants (it being understood for this purpose that the Holder shall be deemed
to own the Warrants commencing on October 9, 1998). In addition, the following
anti-dilution provisions shall protect the Holder from dilution resulting from
the issuance of Common Stock and other securities:



                                      -4-

<PAGE>

              (i) If the Company shall issue or distribute to the holders of
              shares of Common Stock evidence of its indebtedness, any other
              securities of the Company or any cash, property or other assets
              (excluding a subdivision, combination or reclassification, or
              dividend or distribution payable in shares of Common Stock,
              referred to in Subsection 3(a)(ii), and also excluding cash
              dividends or cash distributions paid out of net profits legally
              available therefor in the full amount thereof (any such
              non-excluded event being herein called a "Common Stock Special
              Dividend")), the Per Unit Price shall be adjusted by multiplying
              the Per Unit Price then in effect by a fraction, (A) the numerator
              of which shall be (x) the then current Market Price Per Share of
              Common Stock in effect on the record date of such issuance or
              distribution less (y) the fair market value (as determined in good
              faith by the Company's Board of Directors) of the evidence of
              indebtedness, cash, securities or property, or other assets issued
              or distributed in such Common Stock Special Dividend applicable to
              one share of Common Stock and (B) the denominator of which shall
              be the then current Market Price Per Share of Common Stock in
              effect on the record date of such issuance or distribution. An
              adjustment made pursuant to this Subsection 3(b)(i) shall become
              effective immediately after the record date of any such Common
              Stock Special Dividend.

                      (ii) If the Company shall (A) pay a dividend or make a
              distribution on its capital stock in shares of Common Stock, (B)
              subdivide its outstanding shares of Common Stock into a greater
              number of shares, (C) combine its outstanding shares of Common
              Stock into a smaller number of shares or (D) issue by
              reclassification of its Common Stock any shares of capital stock
              of the Company, the Per Unit Price shall be adjusted by
              multiplying the Per Unit Price by a fraction, the numerator of
              which shall be the number of Common Shares which this Option was
              exercisable for prior to such action and the denominator of which
              shall be the number of Common Shares which a Holder would have
              owned immediately following such action had such Option been
              exercised immediately prior to the record or effective date
              therefor. An adjustment made pursuant to this Subsection 3(a)(ii)
              shall become effective immediately after the record date in the
              case of a dividend or distribution and shall become effective
              immediately after the effective date in the case of a subdivision,
              combination or reclassification.

                      (iii) Except as provided in Subsections 3(a)(i) and 3(e),
              in case the Company shall issue or sell any Common Stock, any
              securities convertible into Common Stock, any rights, options or
              warrants to purchase Common Stock or any securities convertible
              into Common Stock, in each case for a price per share or entitling
              the holders thereof to purchase Common Stock at a price per share
              (determined by dividing (A) the total amount, if any, received or
              receivable by the Company in consideration of the issuance or sale
              of such securities plus the total consideration, if any, payable
              to the Company upon exercise or conversion thereof (the "Common
              Stock Total Consideration") by (B) the number of additional shares
              of Common Stock issued, sold or issuable upon exercise or
              conversion of such securities) which is less than either (i) the
              then current Market Price Per Share of Common Stock in effect on
              the date of such issuance or sale or (ii) the Per Unit Price
              divided by the number of shares of Common Stock that each Unit is
              then exercisable for, the Per Unit Price shall be adjusted as of
              the date of such issuance or sale by multiplying the Per Unit
              Price then in effect by a fraction, the numerator of which shall
              be (x) the sum of (1) the number of shares of Common Stock
              outstanding on the record date of such issuance or sale plus (2)
              the Total Consideration divided by (I) the then current Market
              Price of the Common Stock or (II) the quotient of the Per Unit
              Price divided by the number of shares of Common Stock that each
              Unit is then exercisable for, whichever is greater, and the
              denominator of which shall be (y) the number of shares of Common
              Stock outstanding on the record


                                       -5-


<PAGE>



              date of such issuance or sale plus the maximum number of
              additional shares of Common Stock issued, sold or issuable upon
              exercise or conversion of such securities.

              (iv) In accordance with Section 6 of this Unit Purchase Option,
              notwithstanding the anti-dilution provisions set forth in
              Subsections 3(a)(i)-(iii), if an event set forth in Subsections
              3(a)(i)-(iii) (a "Trigger Event") shall occur, and provided that
              the anti-dilution provisions of the Common Stock, as set forth in
              Article VI of the Subscription Agreement, shall apply to such
              Trigger Event, then any adjustments as a result of the Trigger
              Event shall occur as follows: (A) first, the anti-dilution
              provisions, as set forth in Article VI shall apply; and (B)
              second, the anti-dilution provisions set forth in Subsections
              3(a)(i)-(iii) shall apply only to the extent that the application
              of such provisions shall result in the Holder receiving additional
              shares of capital stock of the Company, having the Per Option Unit
              Price reduced or otherwise further improve the economic position
              of the Holder.

              (b) No adjustment in the Per Unit Price shall be required unless
such adjustment would require an increase or decrease of at least $0.05 per
Unit; provided, however, that any adjustments which by reason of this Section
3(b) are not required to be made shall be carried forward and taken into account
in any subsequent adjustment; provided, further, however, that adjustments shall
be required and made in accordance with the provisions of this Section 3 (other
than this Subsection 3(b)) not later than such time as may be required in order
to preserve the tax-free nature of a distribution to the Holder of this Option.
All calculations under this Section 3 shall be made to the nearest cent or to
the nearest 1/100th of a share, as the case may be. Anything in this Section 3
to the contrary notwithstanding, the Company shall be entitled to make such
reductions in the Per Unit Price, in addition to those required by this Section
3, as it in its discretion shall deem to be advisable in order that any stock
dividend, subdivision of shares or distribution of rights to purchase stock or
securities convertible or exchangeable for stock hereafter made by the Company
to its stockholders shall not be taxable.

              (c) Whenever the Per Unit Price is adjusted as provided in this
Section 3 and upon any modification of the rights of a Holder of Options in
accordance with this Section 3, the Company shall promptly prepare a brief
statement of the facts requiring such adjustment or modification and the manner
of computing the same and cause copies of such certificate to be mailed to the
Holders of the Options. The Company may, but shall not be obligated to unless
requested by the Holders of more than fifty percent (50%) of the outstanding
Options, obtain, at its expense, a certificate of a firm of independent public
accountants of recognized standing selected by the Board of Directors (who may
be the regular auditors of the Company) setting forth the Per Unit Price and the
number of Warrants, Warrant Shares or Common Shares, as the case may be, after
such adjustment or the effect of such modification, a brief statement of the
facts requiring such adjustment or modification and the manner of computing the
same and cause copies of such certificate to be mailed to the Holders of the
Options.

              (d) If the Board of Directors of the Company shall declare any
dividend or other distribution with respect to the Common Stock other than a
cash distribution out of earned surplus, the Company shall mail notice thereof
to the Holders of the Options not less than 10 days prior to the record date
fixed for determining stockholders entitled to participate in such dividend or
other distribution.



                                       -6-


<PAGE>



              (e) No adjustment in the Per Unit Price shall be required in the
case of the issuance by the Company of Common Stock (i) pursuant to the exercise
of any Option or (ii) pursuant to (A) the exercise of any stock options or
warrants currently outstanding or (B) securities issued after the date hereof
pursuant to any Company benefit plan; provided, however, that with respect to
Subsection 3(e)(ii), the issuance of such securities were approved by the Board
of Directors of the Company (or a committee thereof) and were issued at a price
no less than the Market Price of the securities on the date of issuance.

              (f) In case of any capital reorganization or reclassification, or
any consolidation or merger to which the Company is a party other than a merger
or consolidation in which the Company is the continuing corporation, or in case
of any sale or conveyance to another entity of the property of the Company as an
entirety or substantially as a entirety, or in the case of any statutory
exchange of securities with another corporation (including any exchange effected
in connection with a merger of a third corporation into the Company), the Holder
of this Option shall have the right thereafter to receive on the exercise of
this Option the kind and amount of securities, cash or other property which the
Holder would have owned or have been entitled to receive immediately after such
reorganization, reclassification, consolidation, merger, statutory exchange,
sale or conveyance had this Option been exercised immediately prior to the
effective date of such reorganization, reclassification, consolidation, merger,
statutory exchange, sale or conveyance and in any such case, if necessary,
appropriate adjustment shall be made in the application of the provisions set
forth in this Section 3 with respect to the rights and interests thereafter of
the Holder of this Option to the end that the provisions set forth in this
Section 3 shall thereafter corres pondingly be made applicable, as nearly as may
reasonably be, in relation to any shares of stock or other securities or
property thereafter deliverable on the exercise of this Option. The above
provisions of this Subsection 3(f) shall similarly apply to successive
reorganizations, reclassifica tions, consolidations, mergers, statutory
exchanges, sales or conveyances. The Company shall require the issuer of any
shares of stock or other securities or property thereafter deliverable on the
exercise of this Option to be responsible for all of the agreements and
obligations of the Company hereunder. Notice of any such reorganization,
reclassification, consolidation, merger, statutory exchange, sale or conveyance
and of said provisions so proposed to be made, shall be mailed to the Holders of
the Options not less than 30 days prior to such event. A sale of all or
substantially all of the assets of the Company for a consideration consisting
primarily of securities shall be deemed a consolidation or merger for the
foregoing purposes.

              (g) If, as a result of an adjustment made pursuant to this Section
3, the Holder of any Option thereafter surrendered for exercise shall become
entitled to receive shares of two or more classes of capital stock or shares of
Common Stock and other capital stock of the Company, the Board of Directors
(whose determination shall be conclusive and shall be described in a written
notice to the Holder of any Option promptly after such adjustment) shall
determine the allocation of the adjusted Per Unit Price between or among shares
or such classes of capital stock or shares of Common Stock and other capital
stock.

              (h) Upon the expiration of any rights, options, warrants or
conversion privileges, if such shall not have been exercised, the number of
Units purchasable upon exercise of this Option, to the extent this Option has
not then been exercised, shall, upon such expiration, be readjusted and shall
thereafter be such as they would have been had they been originally adjusted (or
had the original adjustment not been required, as the case may be) on the basis
of (i) the fact that Common Stock, if any, actually issued or sold upon the
exercise of such rights, options, warrants or conversion privileges, and (ii)
the fact that such shares of Common Stock, if any, were


                                       -7-


<PAGE>



issued or sold for the consideration actually received by the Company upon such
exercise plus the consideration, if any, actually received by the Company for
the issuance, sale or grant of all such rights, options, warrants or conversion
privileges whether or not exercised; provided, however, that no such
readjustment shall have the effect of decreasing the number of Units purchasable
upon exercise of this Option by an amount in excess of the amount of the
adjustment initially made in respect of the issuance, sale or grant of such
rights, options, warrants or conversion privileges.

              (i) Whenever the Per Unit Price payable upon exercise of each
Option is adjusted pursuant to this Section 3, (i) the number of shares of
Common Stock included in a Unit shall simultaneously be adjusted by multiplying
the number of shares of Common Stock included in a Unit immediately prior to
such adjustment by the Per Unit Price in effect immediately prior to such
adjustment and dividing the product so obtained by the Per Unit Price, as
adjusted and (ii) the number of shares of Common Stock or other securities
issuable upon exercise of the Warrants included in the Units and the exercise
price payable for each of the Warrant Shares (initially $0.50 per Warrant Share,
subject to adjustment) pursuant to the Warrant terms shall be adjusted in
accordance with the terms of the Warrant Agreement applicable to holders of such
Warrants.

              (j) In case any event shall occur as to which the other provisions
of this Section 3 are not strictly applicable but as to which the failure to
make any adjustment would not fairly protect the purchase rights represented by
this Option in accordance with the essential intent and principles hereof then,
in each such case, the Majority of Holders may appoint a firm of independent
public accountants of recognized national standing reasonably acceptable to the
Company, which shall give their opinion as to the adjustment, if any, on a basis
consistent with the essential intent and principles established herein,
necessary to preserve the purchase rights represented by the Options. Upon
receipt of such opinion, the Company will promptly mail a copy thereof to the
Holder of this Option and shall make the adjustments described therein. The fees
and expenses of such independent public accountants shall be borne by the
Company.

              (k) In case the Company shall modify the rights of conversion,
exchange or exercise of any of the securities referred to in Section 3(a)(iii)
or any other securities of the Company convertible, exchangeable or exercisable
for shares of Common Stock, for any reason other than an event that would
require adjustment to prevent dilution, so that the consideration per share
received by the Company after such modification is less than either (x) the Per
Unit Price divided by the number of shares of Common Stock that each Unit is
then exercisable for or (y) the Market Price per Share of Common Stock as of the
date prior to such modification, then such securities, to the extent not
theretofore exercised, converted or exchanged, shall be deemed to have expired
or terminated immediately prior to the date of such modification and the Company
shall be deemed, for purposes of calculating any adjustments pursuant to this
Section 3, to have issued such new securities upon such new terms on the date of
modification. Such adjustment shall become effective as of the date upon which
such modification shall take effect.




                                      -8-

<PAGE>

                      4. Fully Paid Stock; Taxes. The Company agrees that the
shares of the Common Stock represented by each and every certificate for Common
Shares delivered on the exercise of this Option and the shares of Common Stock
delivered upon the exercise of the Warrants, shall at the time of such delivery,
be validly issued and outstanding, fully paid and nonassessable, and not subject
to preemptive rights or rights of first refusal, and the Company will take all
such actions as may be necessary to assure that the par value or stated value,
if any, per share of the Common Stock is at all times equal to or less than the
then Per Unit Price. The Company further covenants and agrees that it will pay,
when due and payable, any and all Federal and state stamp, original issue or
similar taxes which may be payable in respect of the issue of any Warrant Share,
Common Share or any certificate thereof to the extent required because of the
issuance by the Company of such security.

                      5. Registration Under Securities Act of 1933.

                      (a) The Holder shall, with respect to the Common Shares
only, have the right to participate in the registration rights granted to
holders of Registrable Securities pursuant to Section 5 of the subscription
agreements (the "Subscription Agreements") between such holders and the Company
that were entered into at the time of the initial sale of the Units. By
acceptance of this Option, the Holder agrees to comply with the provisions in
Section 5 of the Subscription Agreement to same extent as if it were a
party thereto.

                      (b) Until all Common Shares and Warrant Shares have been
sold under a Registration Statement or pursuant to Rule 144 under the Act, the
Company shall use its reasonable best efforts to file with the Securities and
Exchange Commission all current reports and the information as may be necessary
to enable the Holder to effect sales of its shares in reliance upon Rule 144
promulgated under the Act.

                      6. Article VI Rights. Upon exercise of this Option, the
Holder shall be entitled to the contractual rights set forth in Article VI of
the Subscription Agreement to the same extent as if such Units had been
purchased in the Offering, it being understood and agreed that the Holder shall
receive additional shares of Common Stock upon the exercise of this Option which
would have been issued to the Holder pursuant to Article VI of the Subscription
Agreement as if the Holder had held the shares of Common Stock hereunder since
the Final Closing Date.

                      7. Investment Intent; Limited Transferability.

                      (a) The Holder represents, by accepting this Option, that
it understands that this Option and any securities obtainable upon exercise of
this Option have not been registered for sale under Federal or state securities
laws and are being offered and sold to the Holder pursuant to one or more
exemptions from the registration requirements of such securities laws. In the
absence of an effective registration of such securities or an exemption
therefrom, any certificates for such securities shall bear the legend set forth
on the first page hereof. The Holder understands that it must bear the economic
risk of its investment in this Option and any securities obtainable upon
exercise of this Option for an indefinite period of time, as this Option and
such securities have not been registered under Federal or state securities laws
and therefore cannot be sold unless subsequently registered under such laws,
unless an exemption from such registration is available.



                                      -9-

<PAGE>

                      (b) The Holder, by his acceptance of its Option,
represents to the Company that it is acquiring this Option and will acquire any
securities obtainable upon exercise of this Option for its own account for
investment and not with a view to, or for sale in connection with, any
distribution thereof in violation of the Act. The Holder agrees that this Option
and any such securities will not be sold or otherwise transferred unless (i) a
registration statement with respect to such transfer is effective under the Act
and any applicable state securities laws or (ii) such sale or transfer is made
pursuant to one or more exemptions from the Act.

                      (c) This Option may not be sold, transferred, assigned or
hypothecated for six months from the date hereof except (i) to any firm or
corporation that succeeds to all or substantially all of the business of
Paramount Capital, Inc., (ii) to any of the officers, employees, associates or
affiliated companies of Paramount Capital, Inc., or of any such successor firm,
(iii) to any NASD member participating in the Offering or any officer or
employee of any such NASD member or (iv) in the case of an individual, pursuant
to such individual's last will and testament or the laws of descent and
distribution, and is so transferable only upon the books of the Company which it
shall cause to be maintained for such purpose. The Company may treat the
registered Holder of this Option as he or it appears on the Company's books at
any time as the Holder for all purposes. The Company shall permit any Holder of
an Option or its duly authorized attorney, upon written request during ordinary
business hours, to inspect and copy or make extracts from its books showing the
registered holders of Options. All Options issued upon the transfer or
assignment of this Option will be dated the same date as this Option, and all
rights of the holder thereof shall be identical to those of the Holder.

                      8. Loss, etc., of Option. Upon receipt of evidence
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Option, and of indemnity reasonably satisfactory to the Company, if lost,
stolen or destroyed, and upon surrender and cancellation of this Option, if
mutilated, the Company shall execute and deliver to the Holder a new Option of
like date, tenor and denomination.

                      9. Option Holder Not Stockholder. This Option does not
confer upon the Holder any right to vote or to consent to or receive notice as a
stockholder of the Company, as such, in respect of any matters whatsoever, or
any other rights or liabilities as a stockholder, prior to the exercise hereof;
this Option does, however, confer certain rights and require certain notices to
Holders as set forth herein.

                      10. Communication. No notice or other communication under
this Option shall be effective unless, but any notice or other communication
shall be effective and shall be deemed to have been given if, the same is in
writing and is mailed by first-class mail, postage prepaid, addressed to:

                      (a) the Company at Procept, Inc., 840 Memorial Drive,
              Boston, MA 02139, Attn: President or such other address as the
              Company has designated in writing to the Holder, or

                      (b) the Holder at c/o Paramount Capital, Inc., 787 Seventh
              Avenue, New York, NY 10019 or other such address as the Holder has
              designated in writing to the Company.



                                      -10-

<PAGE>

                      11. Headings. The headings of this Option have been
inserted as a matter of convenience and shall not affect the construction
hereof.

                      12. Applicable Law. This Option shall be governed by and
construed in accordance with the law of the State of New York without giving
effect to the principles of conflicts of law thereof.

                      13. Amendment, Waiver, etc. Except as expressly provided
herein, neither this Option nor any term hereof may be amended, waived,
discharged or terminated other than by a written instrument signed by the party
against whom enforcement of any such amendment, waiver, discharge or termination
is sought; provided, however, that any provisions hereof may be amended, waived,
discharged or terminated upon the written consent of the Company and the then
current Majority of the Holders of the Options only.


                                      -11-


<PAGE>




                      IN WITNESS WHEREOF, the Company has caused this Option to
be signed by its President and attested by its Secretary this __th day of April,
1998.


                                                    Procept, Inc.



                                                    By:
                                                        ----------------------
                                                    Name:
                                                    Title:


ATTEST:



---------------------------
       Secretary





                                      -12-


<PAGE>



                                  SUBSCRIPTION
                                  ------------

                      The undersigned, __________________________, pursuant to
the provisions of the foregoing Option, hereby agrees to subscribe for and
purchase ________________ Units of Procept, Inc., each Unit consisting of Common
Stock, $.001 par value, and Class C Warrants to purchase ___________ share(s) of
Common Stock, covered by said Option, and makes payment therefor in full at the
price per share provided by said Option. The undersigned hereby confirms the
representations and warranties made by it in the Option.

Dated:_______________                            Signature:____________________

                                                 Address:______________________



                                  SUBSCRIPTION
                                  ------------
                                (promissory note)

                      The undersigned, __________________________, pursuant to
the provisions of the foregoing Option, hereby agrees to subscribe for and
purchase ________________ shares of the Common Stock, par value $.001, and Class
C Warrants to purchase ______________ share(s) of Common Stock of Procept, Inc.
covered by said Option, and makes payment therefor in full at the price per
share provided by said Option by delivery of the attached Promissory Note. The
undersigned hereby confirms the representations and warranties made by it in the
Option and in the attached Promissory Note.

Dated:_______________                           Signature:______________________

                                                 Address:_______________________



                                CASHLESS EXERCISE
                                -----------------

                      The undersigned _______________________, pursuant to the
provisions of the foregoing Option, hereby elects to exchange its Option for
__________ Units, each Unit consisting of Common Stock, $.001 par value, and
Class C Warrants to purchase __________ share(s) of Common Stock, pursuant to
the cashless exercise provisions of the Option. The undersigned hereby confirms
the representations and warranties made by it in the Option.

Dated:_______________                            Signature:____________________

                                                 Address:______________________






                                      -13-


<PAGE>



                                   ASSIGNMENT
                                   ----------

                      FOR VALUE RECEIVED ______________________ hereby sells,
assigns and transfers unto ____________________________ the foregoing Option and
all rights evidenced thereby, and does irrevocably constitute and appoint
_____________________, attorney, to transfer said Option on the books of
Procept, Inc.

Dated:_______________                            Signature:____________________

                                                 Address:______________________



                               PARTIAL ASSIGNMENT
                               ------------------

                      FOR VALUE RECEIVED ___________________________ hereby
assigns and transfers unto ____________________________ the right to purchase
________ Units of Procept Inc., each Unit consisting of Common Stock, $.001 par
value, and Class C Warrants to purchase ______________ share(s) of Common Stock,
covered by the foregoing Option, and a proportionate part of said Option and the
rights evidenced thereby, and does irrevocably constitute and appoint
____________________, attorney, to transfer that part of said Option on the
books of Procept, Inc.

Dated:_________________                          Signature:____________________

                                                 Address:______________________



                                      -14-


<PAGE>



                                     [Form]

                                 PROMISSORY NOTE

                                               $[           ] New York, New York
                                                                     [         ]

                      [Unitholder] ("Borrower"), for value received, hereby
promises to pay to the order of [Company name] (together with any such
subsequent holder of this Note, the "Holder" or the "Company") the sum of [ ]($
), or such lesser amount as shall then equal the outstanding principal amount
hereof. Such amount shall be due and payable on October 7, 2003 (the "Maturity
Date"), together with interest thereon at a rate per annum equal to the prime
rate as stated by Citibank, N.A. as of the date hereof, (the "Interest Rate"),
and which shall be calculated on the basis of a 360-day year for actual days
elapsed, on the terms and conditions set forth hereinafter. Payment for all
amounts due hereunder shall be made by certified check or wire transfer to the
Holder at c/o [ ] Attn: [President], or other such address as the Holder may
designate by notice to Borrower. If this Promissory Note is prepaid in whole or
in part by the tendering of shares pursuant to Paragraph 2 below, the repayment
date shall be the date on which the Borrower delivers a notice to the Company in
accordance with Paragraph 4 irrevocably stating the Borrower's intention to
repay the Promissory Note by tendering such shares. The Borrower is delivering
this Promissory Note as payment of the exercise price for the purchase of the
shares of Common Stock (the "Stock") underlying the Unit dated [ ] (the "Unit").
The Promissory Note shall be secured by the Stock which the Holder shall hold in
safe-keeping as collateral for the indebtedness represented by this Promissory
Note.

                      1. Prepayment; Repayment. The Borrower may at any time
prepay in whole or in part the principal sum, plus accrued interest to date of
payment, of this Note, without penalty or premium. All sums paid hereon shall be
applied first to accrued, unpaid interest on this Note and the balance, if any,
to the reduction of the principal hereof. This Note shall not be due and payable
until the Maturity Date. On the Maturity Date, the entire principal amount of,
and all accrued interest on, this Note shall automatically become immediately
due and payable without presentment, demand, protest or other formalities of any
kind, all of which are hereby expressly waived by the Company.

                      2. Prepayment or Repayment by Tendering of Shares. Any
prepayment or repayment may be made by instructing the Company to withhold that
number of shares of Common Stock and/or Warrants currently held by the Company
as collateral for this Promissory Note in accordance with Paragraph 1(a)(iii) of
the Unit Purchase Option and having a value, based upon the Market Price
(assuming the Exchange Date referenced therein is the date such instruction is
received by the Company) (as determined in the Unit Purchase Option) of the
Common Stock, equal to the outstanding principal sum plus accrued interest. The
Company will deliver the balance of the securities not withheld pursuant to the
immediately preceding sentence of this Paragraph 2 to the Borrower at the
address set forth in Paragraph 4 below within five (5) days of the date of such
prepayment or repayment, as the case may be.



<PAGE>



                      3. Events of Default. If any events specified in this
Paragraph 3 shall occur and continue uncured for a period of 90 days following
notice from the lender such event has occurred(herein individually referred to
as an "Event of Default"), the Holder of the Note may, so long as such condition
exists, declare the entire principal and unpaid accrued interest hereon
immediately due and payable, by notice in writing to Borrower:

                      3.1. Failure to pay the principal and unpaid accrued
interest of the Note when due and payable; or

                      3.2. The institution by Borrower of proceedings to be
adjudicated as bankrupt or insolvent, or the consent by Borrower to institution
of bankruptcy or insolvency proceedings against Borrower or the filing by
Borrower of a petition or answer or consent seeking reorganization or release
under the federal Bankruptcy Act, or any other applicable federal or state law,
or the consent by Borrower to the filing of any such petition or the appointment
of a receiver, liquidator, assignee, trustee or other similar official for all
or any substantial part of its property, of the taking of any action by Borrower
in furtherance of any such action; or

                      3.3. If, within sixty (60) days after the commencement of
an action against Borrower (and service of process in connection therewith on
Borrower) seeking any bankruptcy, insolvency, reorganization, liquidation or
similar relief under any present or future statute, law of regulation, such
action shall not have been resolved in favor of Borrower of all orders or
proceedings thereunder affecting the property of Borrower stayed, or if the stay
of any such order or proceeding shall thereafter be set aside, or if, within
sixty (60) days after the appointment without the consent or acquiescence of
Borrower of any trustee or receiver for all or any substantial part of the
property of Borrower, such appointment shall not have been vacated.


                      4. Notices. Any notice required, desired or permitted to
be given hereunder shall be in writing and shall be delivered personally, sent
certified or registered United States mail, return receipt requested or sent by
overnight courier service addressed to:

                      If to the Holder:

                               c/o [company name]
                               [address]
                               Attn: President

                      If to Borrower:

                               [name and address]

Such notices shall be deemed given (i) if delivered personally, upon delivery,
(ii) if mailed as aforesaid, two (2) business days after deposit in the United
States mail and (iii) if sent by overnight courier service one (1) business day
after deposit with the courier service. Any party may change its address by
notice to the other party given in accordance with this section.




<PAGE>


                      IN WITNESS WHEREOF, the Borrower has caused this Note to
be issued this [ ] day of [ ] [ ].



                                                          BORROWER:


                                                          ----------------------
                                                          Name:
                                                          Address:


                                                          ----------------------