Document:

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                                                                     Exhibit 4.1

                         FORM OF SUBSCRIPTION AGREEMENT

                  SUBSCRIPTION AGREEMENT (this "Agreement") made as of the date
set forth on the signature page hereof between InKine Pharmaceutical Company,
Inc., a New York corporation, (the "Company") and the undersigned (the
"Subscriber").

                                   WITNESSETH:

                  WHEREAS, the Company is offering in a private placement to
accredited investors (the "Offering") a minimum of 1.5 million shares of its
Common Stock, par value $.0001 per share, (the "Common Stock") (the "Minimum
Offering") and a maximum of 2.5 million shares of Common Stock (the "Maximum
Offering"), with an option in favor of the Placement Agent to offer up to an
additional 500,000 shares to cover overallotments, all at a purchase price of
$3.80 per share. The shares of Common Stock offered hereby are sometimes
referred to as the "Shares;"

                  WHEREAS, the Subscriber desires to purchase that number of
Shares set forth on the signature page hereof on the terms and conditions
hereinafter set forth; and

                  WHEREAS, the Company has engaged Leerink Swann & Company (the
"Placement Agent") as placement agent for the Offering on a "best-efforts"
basis.

                  NOW, THEREFORE, in consideration of the premises and the
mutual representations and covenants hereinafter set forth, the parties hereto
agree as follows:

I.        SUBSCRIPTION FOR SHARES AND REPRESENTATIONS BY SUBSCRIBER

                  1.1 Subject to the terms and conditions hereinafter set forth,
the Subscriber hereby irrevocably subscribes for and agrees to purchase from the
Company such number of Shares as is set forth upon the signature page hereof at
a price equal to the calculation of the above mentioned formula per Share and
the Company agrees to sell such Shares to the Subscriber for said purchase
price. The purchase price is payable by personal or business check, wire
transfer of immediately available funds or money order made payable to U.S. Bank
National, Escrow Agent, F/B/O InKine Pharmaceutical Company, Inc."
contemporaneously with the execution and delivery of this Agreement by the
Subscriber.

                  All wires should be sent to:

                  BBK: U.S. Bank N.A.

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                  ABA #091000022

                  BNF: U.S. Bank Trust N.A./AC #180121167365
                  OBI: TFM Wire Clearing A/C #47300017
                  Ref: InKine/Leerink Escrow Attn: Chad Myers 651-244-8542

                  Certificates for the Shares will be delivered by the Company
to the Subscriber within 2 business days of the Closing of the Offering
applicable to the Subscriber as set forth in Section III hereof.

                   1.2 The Subscriber recognizes that the purchase of Shares
involves a high degree of risk in that (i) the Company remains a development
stage business with a limited operating history and requires substantial funds
in addition to the proceeds of the Offering; (ii) an investment in the Company
is highly speculative and only investors who can afford the loss of their entire
investment should consider investing in the Company; (iii) the Subscriber may
not be able to liquidate its investment; (iv) transferability of the Shares is
extremely limited; and (v) in the event of a disposition, the Subscriber could
sustain the loss of its entire investment.

                   1.3 The Subscriber represents that the Subscriber is an
"accredited investor" as such term is defined in Rule 501 of Regulation D
promulgated under the Securities Act of 1933, as amended, (the "Act") as
indicated by the responses to the questions contained in Section VII hereof, and
that the Subscriber is able to bear the economic risk and illiquidity of an
investment in the Shares.

                   1.4 The Subscriber hereby acknowledges and represents that
(i) the Subscriber has prior investment experience, including investment in
non-listed and unregistered securities, or that the Subscriber has employed the
services of an investment advisor, attorney and/or accountant to read all of the
documents furnished or made available by the Company both to the Subscriber and
to all other prospective investors to evaluate the merits and risks of such an
investment on the Subscriber's behalf; (ii) the Subscriber recognizes the highly
speculative nature of an investment in the Shares; and (iii) the Subscriber is
able to bear the economic risk and illiquidity which the Subscriber assumes by
investing in the Shares.

                   1.5 The Subscriber hereby acknowledges receipt and careful
review of the Confidential Offering Package dated March 22, 2000; hereby
represents that the Subscriber has

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been furnished by the Company during the course of this transaction with all
information regarding the Company which the Subscriber has requested or desired
to know; has been afforded the opportunity to ask questions of and receive
answers from duly authorized officers or other representatives of the Company
concerning the terms and conditions of the Offering; and has received any
additional information which the Subscriber has requested.

                   1.6 (a) In making the decision to invest in the Shares, the
Subscriber has relied solely upon the information provided by the Company in the
Offering Package. To the extent necessary, the Subscriber has retained, at its
own expense, and relied upon the advice of appropriate professionals regarding
the investment, tax and legal merits and consequences of this Agreement and its
purchase of the Shares hereunder. The Subscriber acknowledges and agrees that
the Placement Agent has not supplied any information for inclusion in the
Offering Package other than information furnished in writing to the Company by
the Placement Agent specifically for inclusion in the Offering Package relating
to the Placement Agent, that the Placement Agent has no responsibility for the
accuracy or completeness of the Offering Package and that the Subscriber has not
relied upon the independent investigation or verification, if any, which may
have been undertaken by the Placement Agent.

              (b) The Subscriber covenants that (i) the Subscriber was contacted
regarding the sale of the Shares by the Placement Agent (or an authorized agent
or representative thereof) with whom the Subscriber had a prior substantial
pre-existing relationship and (ii) no Shares were offered or sold to it by means
of any form of general solicitation or general advertising, and in connection
therewith the Subscriber did not (A) receive or review any advertisement,
article, notice or other communication published in a newspaper or magazine or
similar media or broadcast over television or radio, whether closed circuit or
generally available; or (B) attend any seminar, meeting or industry investor
conference whose attendees were invited by any general solicitation or general
advertising.

                  1.7 The Subscriber hereby acknowledges that the Offering has
not been reviewed by the United States Securities and Exchange Commission (the
"SEC") because of the Company's representations that this Offering is intended
to be exempt from the registration requirements of Section 5 of the Act pursuant
to Sections 3(b), 4(2), and 4(6) thereof and Regulation D promulgated under the
Act. The Subscriber agrees that the Subscriber will not sell or otherwise
transfer the Shares unless they are registered under the Act or unless an
exemption from such registration is available.

                  1.8 The Subscriber understands that none of the Shares have
been registered under the Act by reason of a claimed exemption under the
provisions of the Act which depends, in part, upon the Subscriber's investment
intention. In this connection, the Subscriber hereby represents that the
Subscriber is purchasing the Shares for the Subscriber's own account for
investment and not with a view toward the resale or distribution thereof to
others. The Subscriber, if an entity, was not formed for the purpose of
purchasing the Shares. The Subscriber understands that Rule 144 promulgated
under the Act requires, among other conditions, a one-year holding period prior
to the resale (in limited amounts) of securities acquired in a non-public
offering without having to satisfy the registration requirements under

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the Act.

                  1.9 The Subscriber understands and hereby acknowledges that
the Company is under no obligation to register the Shares under the Act or any
state securities or "blue sky" laws other than as set forth in Section V. The
Subscriber consents that the Company may, if it desires, permit the transfer of
the Shares out of the Subscriber's name only when the Subscriber's request for
transfer is accompanied by an opinion of counsel reasonably satisfactory to the
Company that neither the sale nor the proposed transfer results in a violation
of the Act or any applicable state "blue sky" laws (collectively, "Securities
Laws"). The Subscriber agrees to hold the Company and the Placement Agent and
their respective directors, officers, employees, agents and controlling persons
and their respective heirs, representatives, successors and assigns harmless and
to indemnify them against all losses, damages, liabilities, costs and expenses
incurred by them as a result of any breach of any representation, warranty or
acknowledgement, or any misrepresentation made by the Subscriber contained in
this Agreement (including the Confidential Investor Questionnaire contained in
Section VII herein) or any sale or distribution by the Subscriber in violation
of the Securities Laws.

                  1.10 The Subscriber consents to the placement of a legend on
any certificate or other document evidencing the Shares indicating that such
Shares have not been registered under the Act or any state securities or "blue
sky" laws and setting forth or referring to the restrictions on transferability
and sale thereof contained in this Agreement. The Subscriber is aware that the
Company will make a notation in its appropriate records and issue "stop
transfer" instructions to its transfer agent with respect to the restrictions on
the transferability of such Shares.

                  1.11 The Subscriber understands that the Company will review
this Agreement and hereby gives authority to the Company to call Subscriber's
bank or place of employment (in a call in which the Placement Agent
participates) or otherwise review the financial standing of the Subscriber; and
it is further agreed that upon their mutual agreement the Placement Agent and
the Company reserve the unrestricted right, without further documentation or
agreement on the part of the Subscriber, to reject or limit any subscription, to
accept subscriptions for Shares and to close the Offering to the Subscriber at
any time.

                  1.12 The Subscriber hereby represents that the address of the
Subscriber furnished by the Subscriber on the signature page hereof is the
Subscriber's principal residence if the Subscriber is an individual or its
principal business address if it is a corporation or other entity.

                  1.13 The Subscriber represents that the Subscriber has full
power and authority (corporate, statutory and otherwise) to execute and deliver
this Agreement and to purchase the Shares subscribed for hereby. This Agreement
constitutes the legal, valid and binding obligation of the Subscriber,
enforceable against the Subscriber in accordance with its terms.

                  1.14 If the Subscriber is a corporation, partnership, limited
liability company, trust, employee benefit plan, individual retirement account,
Keogh Plan, or other entity, then (a) it is authorized and qualified to become
an investor in the Company and the person signing this

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Agreement on behalf of such entity has been duly authorized by such entity to do
so, and (b) it is duly organized, validly existing and in good standing under
the laws of the jurisdiction of its organization.

                  1.15 The Subscriber acknowledges that if he or she is a
registered representative of a National Association of Securities Dealers, Inc.
("NASD") member firm, he or she must give such firm the notice required by the
NASD's Rules of Fair Practice, receipt of which must be acknowledged by such
firm in Section 7.4 below.

                  1.16 The Subscriber represents and warrants that it has not
engaged, consented to nor authorized any broker, finder or intermediary to act
on its behalf, directly or indirectly, as a broker, finder or intermediary in
connection with the transactions contemplated by this Agreement. The Subscriber
shall indemnify and hold harmless the Company from and against all fees,
commissions or other payments owing to any such person or firm acting on behalf
of such Subscriber hereunder.

                  1.17 The Subscriber acknowledges that (a) the Company has
engaged, consented to and authorized the Placement Agent in connection with the
transactions contemplated by this Agreement, (b) the Company shall pay the
Placement Agent a commission and reimburse the Placement Agent's expenses in
accordance with the Placement Agency Agreement (as defined in Section 5.1(c)
below), and the Company shall indemnify and hold harmless the Subscriber from
and against all fees, commissions or other payments owing by the Company to the
Placement Agent or any other person or firm acting on behalf of the Company
hereunder and (c) registered representatives of the Placement Agent and/or its
designees (including, without limitation, registered representatives of the
Placement Agent and/or its designees who participate in the Offering and sale of
the securities sold in the Offering) will be paid a portion of the commissions
paid to the Placement Agent including a portion of the Placement Warrants (as
defined in Section 5.1(c) below).

                  1.18 The Subscriber, whose name appears on the signature line
below, shall be the beneficial owner of the Shares for which such Subscriber
subscribes.

                  1.19 The Subscriber agrees that from the time the Subscriber
first received the Offering Package until a point in time equal to the earlier
of (i) the date that the Registration Statement (as defined in Section 5.2(a))
is declared effective by the SEC or (ii) one year from the date of the Offering
Package, the Subscriber has not and shall not, directly or indirectly, through
related parties, affiliates or otherwise, (A) sell "short" or "short against the
box" (as those terms are generally understood) any equity security of the
Company or (B) otherwise engage in any transaction that involves hedging of the
Subscriber's position in any equity security of the Company.

II.      REPRESENTATIONS BY THE COMPANY

         The Company hereby represents and warrants to the Subscriber that:

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                  2.1 Organization, Good Standing and Qualification. The Company
is a corporation duly organized, validly existing and in good standing under the
laws of the State of New York and has full corporate power and lawful authority
to conduct its business as described in the Offering Package. The Company is
duly qualified to do business as a foreign corporation and is in good standing
in the Commonwealth of Pennsylvania and in each jurisdiction in which the nature
of the business conducted, or as proposed to be conducted in the Offering
Package, by it or the properties owned, leased or operated by it, makes such
qualification or licensing necessary and where the failure to be so qualified or
licensed would have a material adverse effect upon the business, prospects or
financial condition of the Company other than Pennsylvania, where the Company
will be so qualified prior to the Closing (as defined in Section 3.2).

                  2.2 Capitalization and Voting Rights. The authorized, issued
and outstanding capital stock of the Company is as set forth in the Offering
Package; all issued and outstanding shares of capital stock of the Company are
validly issued, fully paid and nonassessable. Except as set forth in the
Offering Package, there are no outstanding options, warrants, agreements,
commitments, convertible securities, preemptive rights or other rights to
subscribe for or to purchase any shares of capital stock of the Company nor are
there any agreements, promises or commitments to issue any of the foregoing, or
discussions concerning same, which have not been disclosed in writing. Except as
set forth in the Offering Package, in this Agreement and as otherwise required
by law, there are no restrictions upon the voting or transfer of the Shares
pursuant to the Company's Certificate of Incorporation, as amended, (the
"Certificate of Incorporation"), By-laws or other governing documents or any
agreement or other instruments to which the Company is a party or by which the
Company is bound.

                  2.3 Authorization; Enforceability. The Company has all
corporate right, power and authority to enter into this Agreement and to
consummate the transactions contemplated hereby. All corporate action on the
part of the Company, its directors and stockholders necessary for the
authorization, execution, delivery and performance of this Agreement by the
Company, the authorization, sale, issuance and delivery of the Shares and the
performance of the Company's obligations hereunder has been taken. This
Agreement has been duly executed and delivered by the Company and constitutes a
legal, valid and binding obligation of the Company, enforceable against the
Company in accordance with its terms, subject to laws of general application
relating to bankruptcy, insolvency and the relief of debtors and rules of law
governing specific performance, injunctive relief or other equitable remedies,
and to limitations of public policy. The Shares have been duly and validly
authorized and, upon the issuance and delivery thereof and payment therefor as
contemplated by this Agreement, will be free and clear of liens, duly and
validly authorized and issued, fully paid and nonassessable. The issuance and
sale of the Shares contemplated hereby will not give rise to any preemptive
rights or rights of first refusal on behalf of any person.

2.4      No Conflict; Governmental Consents.

                  (a) The execution and delivery by the Company of this
Agreement and the consummation of the transactions contemplated hereby will not
result in the violation of any law,

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statute, rule, regulation, order, writ, injunction, judgment or decree of any
court or governmental authority to or by which the Company is bound, or of any
provision of the Certificate of Incorporation or By-laws of the Company, and
will not conflict with, or result in a breach or violation of, any of the terms
or provisions of, or constitute (with due notice or lapse of time or both) a
default under, any lease, loan agreement, mortgage, security agreement, trust
indenture or other agreement or instrument to which the Company is a party or by
which it is bound or to which any of its properties or assets is subject, nor
result in the creation or imposition of any lien upon any of the properties or
assets of the Company.

                  (b) No consent, approval, authorization or other order of any
governmental authority or other third-party is required to be obtained by the
Company in connection with the authorization, execution and delivery of this
Agreement or with the authorization, issuance and sale of the Shares, except
such filings as may be required to be made, and which shall have been made at or
prior to the required time, with the SEC, the NASD and the National Association
of Securities Dealers Automated Quotation System ("Nasdaq"), and with any state
or foreign blue sky or securities regulatory authority.

                  2.5 Licenses. Except as may be set forth in the Offering
Package, the Company has all licenses, permits and other governmental
authorizations currently required for the conduct of its business or ownership
of properties and is in all material respects complying therewith, except for
any licenses, permits or other governmental authorizations which would not
materially adversely affect the business, property, financial condition, results
of operations or prospects of the Company.

                  2.6 Litigation. The Company knows of no pending or threatened
legal or governmental proceedings against the Company which could materially
adversely affect the business, property, financial condition, results of
operations or prospects of the Company.

                  2.7 Accuracy of Reports. All material reports required to be
filed by the Company within the three years prior to the date of this Agreement
under the Securities Exchange Act of 1934, as amended, (the "Exchange Act") have
been duly filed with the SEC, complied at the time of filing in all material
respects with the requirements of their respective forms and, except to the
extent updated or superseded by the Offering Package or any subsequently filed
report, to the best of the Company's knowledge, were complete and correct in all
material respects as of the dates at which the information was furnished, and
contained (as of such dates) no untrue statement of a material fact or omitted
to state a material fact necessary in order to make the statements contained
therein, in light of the circumstances under which they were made, not
misleading.

                  2.8 Accuracy of Offering Package. No information set forth in
the Offering Package contains any untrue statement of a material fact or omits
to state a material fact necessary in order to make the statements contained
therein, in light of the circumstances under which they were made, not
misleading.

                  2.9 Investment Company. The Company is not an "investment
company"

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within the meaning of such term under the Investment Company Act of 1940, as
amended, and the rules and regulations of the SEC thereunder.

                  2.10 Listing. The Company shall promptly file an Application
for Listing of Additional Shares with the Nasdaq SmallCap Market and hereby
represents and warrants to the Placement Agent and the Subscriber that it will
take any other necessary action in accordance with the rules of the Nasdaq
SmallCap Market to enable the Shares (and the Common Stock issuable upon
exercise of the Placement Warrants as defined in Section 5.1 (c)) to trade on
the Nasdaq SmallCap Market.

III.     TERMS OF SUBSCRIPTION

                  3.1 The Offering is for a minimum of 1.5 million Shares and a
maximum of 2.5 million Shares. The Shares are offered on a "best efforts" basis.
The Placement Agent, at its option, may offer for sale by the Company up to an
additional 500,000 Shares to cover over-allotments. Subscribers must each
purchase a minimum of 75,000 Shares unless the Company and the Placement Agent
agree to a lesser number.

                  3.2 After the Minimum Offering amount has been subscribed for,
the Company and the Placement Agent shall mutually agree as to the number of
closings and the timing thereof (each, a "Closing") and they will not be
obligated to conduct the first Closing within any specific time following
receipt of subscriptions for the Minimum Offering. The foregoing
notwithstanding, the first Closing is expected to occur no later than April 27,
2000, subject to extension of this Offering for up to an additional 60 days at
the option of the Placement Agent and the Company (such date, as the same may be
extended, the "Closing Date"). The purchase price is payable by personal or
business check, wire transfer of immediately available funds or money order made
payable to "U.S. Bank National, Escrow Agent, F/B/O InKine Pharmaceutical
Company, Inc." as provided in Section 1.1.

                  3.3 Pending the sale of the Shares, all subscription funds
paid hereunder shall be deposited by the Escrow Agent in escrow with U.S. Bank
National. If the Company shall not have obtained subscriptions (including this
subscription) for the Minimum Offering on or before May 19, 2000, then this
subscription shall be void and all funds paid hereunder by the Subscriber shall
be promptly returned to the Subscriber, without deduction therefrom and with
interest thereon, in accordance with Section 3.5 hereof.

                  3.4 The Subscriber hereby authorizes and directs the Company
to deliver the Shares to be issued to the Subscriber pursuant to this Agreement
directly to the Subscriber's account maintained by the Placement Agent or, if no
such account exists, to the residential or business address indicated on the
signature page hereto.

                  3.5 The Subscriber hereby authorizes and directs the Company
to return any funds related to unaccepted subscriptions to the same account from
which the funds were drawn, including any customer account maintained with the
Placement Agent.

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IV.      CONDITIONS TO OBLIGATIONS OF THE SUBSCRIBERS AND THE COMPANY

                  4.1 The Subscribers' obligation to purchase the Shares at the
Closing is subject to the fulfillment on or prior to the date of such Closing of
the following conditions, which conditions may be waived at the option of each
Subscriber to the extent permitted by law:

                  (a) Representations and Warranties. The representations and
warranties made by the Company in Section II hereof shall be true and correct in
all material respects when made, and shall be true and correct in all material
respects on the date of such Closing with the same force and effect as if they
had been made on and as of said date. If any such representations or warranties
shall not be true and accurate in any respect prior to the Closing, the Company
shall give immediate written notice of such fact to the Placement Agent,
specifying which representations or warranties are not true and accurate and the
reason therefor.

                  (b) Covenants. All covenants, agreements and conditions
contained in this Agreement to be performed by the Company on or prior to such
purchase shall have been performed or complied with in all material respects.

                  (c) No Legal Order Pending. There shall not then be in effect
any legal or other order enjoining or restraining the transactions contemplated
by this Agreement.

                  (d) No Law Prohibiting or Restricting Such Sale. There shall
not be in effect any law, rule or regulation prohibiting or restricting such
sale or requiring any consent or approval of any person to issue the Shares
which consent or approval shall not have been obtained (except as may otherwise
be provided in this Agreement).

                  (e) Minimum Subscriptions. The Company shall have received
binding subscriptions for at least the Minimum Offering.

                  (f) Legal Opinion. Upon the Closing, counsel to the Company
shall have delivered to the Placement Agent for the benefit of the Subscribers a
legal opinion with respect to such legal matters relating to this Agreement and
the Offering Package as the Placement Agent may reasonably require.

                  4.2 The Company's obligation to sell the Shares at the Closing
is subject to the fulfillment on or prior to the date of such Closing of the
following conditions, which conditions may be waived at the option of the
Company to the extent permitted by law:

                  (a) Acknowledgements, Representations and Warranties. The
acknowledgements, representations and warranties made by the Subscriber in
Section I hereof shall be true and correct in all material respects when made,
and shall be true and correct in all material respects on the date of such
Closing with the same force and effect as if they had been made on and as of
said date. If any such representations, warranties or acknowledgements shall not
be true and accurate in any respect prior to the Closing, the undersigned shall
give immediate

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written notice of such fact to the Company, to the Placement Agent, and to his
representatives, if any, specifying which representations, warranties or
acknowledgements are not true and accurate and the reason therefor.

                  (b) Covenants. All covenants, agreements and conditions
contained in this Agreement to be performed by the Subscriber on or prior to
such purchase shall have been performed or complied with in all material
respects.

                  (c) No Legal Order Pending. There shall not then be in effect
any legal or other order enjoining or restraining the transactions contemplated
by this Agreement.

                  (d) No Law Prohibiting or Restricting Such Sale. There shall
not be in effect any law, rule or regulation prohibiting or restricting such
sale or requiring any consent or approval of any person to issue the Shares
which consent or approval shall not have been obtained (except as may otherwise
be provided in this Agreement).

                  (e) Minimum Subscriptions. The Company shall have received
binding subscriptions for a least the Minimum Offering.

V.       REGISTRATION RIGHTS

                  5.1 As used in this Agreement, the following terms shall have
the following meanings:

                           (a) "Affiliate" shall mean, with respect to any
Person (as defined below), any other Person controlling, controlled by, or under
direct or indirect common control with, such Person (for the purposes of this
definition "control," when used with respect to any specified Person, shall mean
the power to direct the management and policies of such person, directly or
indirectly, whether through ownership of voting securities, by contract or
otherwise; and the terms "controlling" and "controlled" shall have meanings
correlative to the foregoing).

                           (b) "Business Day" shall mean a day, Monday through
Friday, on which banks are generally open for business in each of New York, New
York; Boston, Massachusetts; and Philadelphia, Pennsylvania;

                           (c) "Holders" shall mean the Subscriber and any
person holding Registrable Securities as defined below (including the
Registrable Securities underlying the Placement Warrants (the "Placement
Warrants") to be granted to the Placement Agent and/or their designees pursuant
to the engagement letter between the Company and the Placement Agent dated March
1, 2000, (the "Placement Agency Agreement")), a holder of the Placement
Warrants, or any person to whom the rights under Section V have been transferred
in accordance with Section 5.9 hereof.

                           (d) "Person" shall mean any person, individual,
corporation, limited liability company, partnership, trust or other
nongovernmental entity or any governmental

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agency, court, authority or other body (whether foreign, federal, state, local
or otherwise).

                           (e) The terms "register," "registered" and
"registration" refer to the registration effected by preparing and filing with
the SEC a registration statement in compliance with the Act, and the declaration
or ordering by the SEC of the effectiveness of such registration statement.

                           (f) "Registrable Securities" shall mean (i) the
Shares and (ii) the shares of Common Stock issuable upon the exercise of the
Placement Warrants; provided, however, that securities shall only be treated as
Registrable Securities if and only for so long as they (A) have not been
disposed of pursuant to a registration statement declared effective by the SEC,
(B) have not been sold in a transaction exempt from the registration and
prospectus delivery requirements of the Act so that all transfer restrictions
and restrictive legends with respect thereto are removed upon the consummation
of such sale, and (C) are held by a Holder or a permitted transferee pursuant to
Section 5.9.

                           (g) "Registration Expenses" shall mean all expenses
incurred by the Company in complying with Section 5.2 hereof, including, without
limitation, all registration, qualification and filing fees, printing expenses,
escrow fees, fees and expenses of counsel for the Company, blue sky fees and
expenses and the expense of any special audits incident to, or required by, any
such registration (but excluding the aggregate fees of legal counsel for all
Holders).

                           (h) "Registration Statement" shall have the meaning
ascribed to such term in Section 5.2 (a).

                           (i) "Registration Period" shall have the meaning
ascribed to such term in Section 5.4 (a).

                           (j) "Selling Expenses" shall mean all underwriting
discounts and selling commissions applicable to the sale of Registrable
Securities and the aggregate fees and expenses of legal counsel for all Holders.

                  5.2 (a) The Company shall, as soon as practicable, but not
later than ten (10) business days after the first Closing Date (such tenth
business day herein referred to as the "Filing Date"), (i) use its best efforts
to file with the SEC a registration statement (the "Registration Statement")
with respect to the resale of the Registerable Securities and use its best
efforts to have such Registration Statement declared effective by the SEC as
soon thereafter as is practical and (ii) cause such Registration Statement to
remain effective until the earlier of such date as the Holders have completed
the distribution described in the Registration Statement and such time as such
Shares are no longer, by reason of Rule 144 (k) under the Act, required to be
registered for the sale thereof by such Holders. If requested by the Placement
Agent, and in accordance with applicable securities laws, the Registration
Statement shall cover the direct sale of such Registrable Securities to the
Holders of such securities.

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                           (b) If the Registration Statement is not filed on or
prior to the Filing Date, then for each successive thirty (30) day period beyond
such Date, the Company shall pay to each Subscriber, in cash, as liquidated
damages and not as a penalty, one percent (1%) of the aggregate purchase price
previously paid by such Subscriber for Shares (or a pro rata amount for any
periods less than thirty (30) days) until such time as the filing is made;
provided, however, such Subscriber shall not be entitled to such cash payment if
and to the extent that such delays are the result of the failure of such
Subscriber to provide the Company with written information necessary to complete
the Registration Statement by the Filing Date.

                  5.3 All Registration Expenses incurred in connection with any
registration, qualification, exemption or compliance pursuant to Section 5.2
shall be borne by the Company. All Selling Expenses relating to the sale of
securities registered by or on behalf of Holders shall be borne by such Holders
pro rata on the basis of the number of securities so registered.

                  5.4 In the case of the registration, qualification, exemption
or compliance effected by the Company pursuant to this Agreement, the Company
shall, upon reasonable request, inform each Holder as to the status of such
registration, qualification, exemption and compliance. At its expense the
Company shall:

                           (a) use its best efforts to keep such registration,
and any qualification, exemption or compliance under state securities laws which
the Holders reasonably request the Company to obtain, continuously effective
until the Holders have completed the distribution described in the registration
statement relating thereto. The period of time during which the Company is
required hereunder to keep the Registration Statement effective is referred to
herein as "the Registration Period." Notwithstanding the foregoing, at the
Company's election, the Company may cease to keep such registration,
qualification, exemption or compliance effective with respect to any Registrable
Securities, and the registration rights of a Holder with respect to such
Registrable Securities shall expire, at such time as the Holder may sell all
Registrable Securities then held by such Holder under Rule 144 under the Act in
a three-month period, but this sentence shall not relieve the Company of any
obligation to comply with this Section V as to any shares of Common Stock
issuable upon exercise of the Placement Warrants;

                           (b) advise the Holders:

                                    (i) when the Registration Statement or any
amendment thereto has been filed with the SEC and when the Registration
Statement or any post-effective amendment thereto has become effective;

                                    (ii) of any request by the SEC for
amendments or supplements to the Registration Statement or the prospectus
included therein or for additional information;

                                    (iii) of the issuance by the SEC of any stop
order suspending the effectiveness of the Registration Statement or the
initiation of any proceedings for such purpose;

                                    (iv) of the receipt by the Company of any
notification with

                                       12
<PAGE>   13
respect to the suspension of the qualification of the Registrable Securities
included therein for sale in any jurisdiction or the initiation or threatening
of any proceeding for such purpose; and

                                    (v) of the happening of any event that
requires the making of any changes in the Registration Statement or the
prospectus so that, as of such date, the statements therein are not misleading
and do not omit to state a material fact required to be stated therein or
necessary to make the statements therein (in the case of the prospectus, in the
light of the circumstances under which they were made) not misleading;

                           (c) make every reasonable effort to obtain the
withdrawal of any order suspending the effectiveness of any Registration
Statement at the earliest possible time;

                           (d) furnish to each Holder, without charge, at least
one copy of such Registration Statement and any post-effective amendment or
supplement thereto, including financial statements and schedules, and, if the
Holder so requests in writing, all exhibits (excluding those incorporated by
reference) in the form filed with the SEC;

                           (e) during the Registration Period, deliver to each
Holder, without charge, a reasonable number of copies of the prospectus included
in such Registration Statement and any amendment or supplement thereto as such
Holder may reasonably request; and the Company consents to the use, consistent
with the provisions hereof, of the prospectus and any amendment or supplement
thereto by each of the selling Holders of Registrable Securities in connection
with the offering and sale of the Registrable Securities covered by the
prospectus and any amendment or supplement thereto;

                           (f) during the Registration Period, deliver to each
Holder, without charge, (i) as soon as practicable (but in the case of the
annual report of the Company to its stockholders, within 120 days after the end
of each fiscal year of the Company) one copy of: (A) its annual report to its
stockholders, if any (which annual report shall contain financial statements
audited in accordance with generally accepted accounting principles in the
United States of America by a firm of certified public accountants of recognized
standing); (B) if not included in substance in its annual report to
stockholders, its annual report on Form 10-K (or similar form); (C) a copy of
the full Registration Statement (excluding exhibits); and (ii) upon reasonable
request, all exhibits excluded by the parenthetical to the immediately preceding
clause (C);

                           (g) prior to any public offering of Registrable
Securities pursuant to any Registration Statement, register or qualify or obtain
an exemption for the offer and sale under the securities or blue sky laws of
such jurisdictions as any such Holders reasonably request in writing, provided
that the Company shall not for any such purpose be required to qualify generally
to transact business as a foreign corporation in any jurisdiction where it is
not so qualified or to consent to general service of process in any such
jurisdiction, and do any and all other acts or things reasonably necessary or
advisable to enable the offer and sale in such jurisdictions of the Registrable
Securities covered by such Registration Statement;

                           (h) cooperate with the Holders to facilitate the
timely preparation and

                                       13
<PAGE>   14
delivery of certificates representing Registrable Securities to be sold pursuant
to any Registration Statement free of any restrictive legends to the extent not
required at such time and in such denominations and registered in such names as
Holders may request at least five (5) business days prior to sales of
Registrable Securities pursuant to such Registration Statement;

                           (i) upon the occurrence of any event contemplated by
Section 5.4(b)(v) above, the Company shall promptly prepare a post-effective
amendment to the Registration Statement or a supplement to the related
prospectus, or file any other required document so that, as thereafter delivered
to purchasers of the Registrable Securities included therein, the prospectus
will not include any untrue statement of a material fact or omit to state any
material fact necessary to make the statements therein, in the light of the
circumstances under which they were made, not misleading; and

                           (j) use its best efforts to comply with all
applicable rules and regulations of the SEC, and make generally available to the
Holders not later than 45 days (or 90 days if the fiscal quarter is the fourth
fiscal quarter) after the end of its fiscal quarter in which the first
anniversary date of the effective date of the Registration Statement occurs, an
earnings statement satisfying the provisions of Section 11(a) of the Act.

                  5.5 The Holders shall have no right to take any action to
restrain, enjoin or otherwise delay any registration pursuant to Section 5.2
hereof as a result of any controversy that may arise with respect to the
interpretation or implementation of this Agreement.

                  5.6 (a) To the extent permitted by law, the Company shall
indemnify each Holder, each underwriter of the Registrable Securities and each
person controlling such Holder and each such underwriter within the meaning of
Section 15 of the Act, with respect to which any registration, qualification or
compliance has been sought pursuant to this Agreement, against all claims,
losses, expenses, costs, damages and liabilities (or action in respect thereof),
including any of the foregoing incurred in settlement of any litigation,
commenced or threatened (subject to Section 5.6(c) below), arising out of or
based on (i) any untrue statement (or alleged untrue statement) of a material
fact contained in any registration statement, prospectus or offering circular,
or any amendment or supplement thereof, incident to any such registration,
qualification or compliance, or based on any omission (or alleged omission) to
state therein a material fact required to be stated therein or necessary to make
the statements therein not misleading in light of the circumstances in which
they were made, or (ii) any violation or alleged violation by the Company of the
Act, the Exchange Act, or any rule or regulation promulgated under the Act or
the Exchange Act, and shall reimburse each Holder, each underwriter of the
Registrable Securities and each person controlling such Holder and each such
underwriter, for legal and other expenses reasonably incurred in connection with
investigating or defending any such claim, loss, damage, liability or action as
incurred; provided that the Company shall not be liable in any such case to the
extent that any untrue statement or omission or allegation thereof is made in
reliance upon and in conformity with written information furnished to the
Company by or on behalf of such Holder or underwriter and stated to be
specifically for use in preparation of such registration statement, prospectus
or offering circular; provided that the Company shall not be liable in any such
case where the claim, loss, damage or liability arises out of or is related to
the failure of the

                                       14
<PAGE>   15
Holder to comply with the covenants and agreements contained in this Agreement
respecting sales of Registrable Securities, and except that the foregoing
indemnity agreement is subject to the condition that, insofar as it relates to
any such untrue statement or alleged untrue statement or omission or alleged
omission made in the preliminary prospectus but eliminated or remedied in the
amended prospectus on file with the SEC at the time the registration statement
becomes effective or in the amended prospectus filed with the SEC pursuant to
Rule 424(b) of the Act or in the prospectus subject to completion under Rule 434
of the Act, which together meet the requirements of Section 10(a) of the Act
(the "Final Prospectus"), such indemnity agreement shall not inure to the
benefit of any such Holder, any such underwriter or any such controlling person,
if a copy of the Final Prospectus furnished by the Company to the Holder for
delivery was not furnished to the person or entity asserting the loss,
liability, claim or damage at or prior to the time such furnishing is required
by the Act and the Final Prospectus would have cured the defect giving rise to
such loss, liability, claim or damage.

                           (b) Each Holder will severally, if Registrable
Securities held by such Holder are included in the securities as to which such
registration, qualification or compliance is being effected, indemnify the
Company, each of its directors and officers, each underwriter of the Registrable
Securities and each person who controls the Company and each underwriter of the
Registrable Securities within the meaning of Section 15 of the Act, against all
claims, losses, expenses, costs, damages and liabilities (or actions in respect
thereof), including any of the foregoing incurred in settlement of any
litigation, commenced or threatened (subject to Section 5.6(c) below), arising
out of or based on any untrue statement (or alleged untrue statement) of a
material fact contained in any registration statement, prospectus or offering
circular, or any amendment or supplement thereof, incident to any such
registration, qualification or compliance or based on any omission (or alleged
omission) to state therein a material fact required to be stated therein or
necessary to make the statements therein not misleading in light of the
circumstances in which they were made, and will reimburse the Company, such
directors and officers, each underwriter of the Registrable Securities and each
person controlling the Company and each underwriter of the Registrable
Securities for reasonable legal and any other expenses or costs reasonably
incurred in connection with investigating or defending any such claim, loss,
damage, liability or action as incurred, in each case to the extent, but only to
the extent, that such untrue statement or omission or allegation thereof is made
in reliance upon, and in conformity with, written information furnished to the
Company by or on behalf of the Holder and stated to be specifically for use in
preparation of such registration statement, prospectus or offering circular;
provided that the indemnity shall not apply to the extent that such claim, loss,
damage or liability results from the fact that a current copy of the prospectus
or offering circular was not made available to the Holder and such current copy
of the prospectus or offering circular would have cured the defect giving rise
to such loss, claim, expense, costs, damage or liability. Notwithstanding the
foregoing, in no event shall a Holder be liable for any such claims, losses,
expenses, costs, damages or liabilities in excess of the proceeds received by
such Holder in that offering, except in the event of fraud by such Holder.

                           (c) Each party entitled to indemnification under this
Section 5.6 (the "Indemnified Party") shall give notice to the party required to
provide indemnification (the "Indemnifying Party") promptly after such
Indemnified Party has actual knowledge of any claim

                                       15
<PAGE>   16
as to which indemnity may be sought, and shall permit the Indemnifying Party to
assume the defense of any such claim or any litigation resulting therefrom,
provided that counsel for the Indemnifying Party, who shall conduct the defense
of such claim or litigation, shall be approved by the Indemnified Party (whose
approval shall not unreasonably be withheld), and the Indemnified Party may
participate in such defense with its own counsel at such Indemnified Party's
expense unless the named parties to any proceeding covered hereby (including any
impleaded parties) include both the Company or any others the Company may
designate and one or more Indemnified Persons, and representation of the
Indemnified Persons and such other parties by the same counsel would be
inappropriate due to actual or potential differing interests between them, and
provided further that the failure of any Indemnified Party to give notice as
provided herein shall not relieve the Indemnifying Party of its obligations
under this Agreement, unless such failure is materially prejudicial to the
Indemnifying Party in defending such claim or litigation. An Indemnifying Party
shall not be liable for any settlement of an action or claim effected without
its written consent (which consent will not be unreasonably withheld).

                           (d) If the indemnification provided for in this
Section 5.6 is held by a court of competent jurisdiction to be unavailable to an
Indemnified Party with respect to any loss, liability, claim, damage, cost or
expense referred to therein, then the Indemnifying Party, in lieu of
indemnifying such Indemnified Party thereunder, shall contribute to the amount
paid or payable by such Indemnified Party as a result of such loss, liability,
claim, damage, cost or expense in such proportion as is appropriate to reflect
the relative fault of the Indemnifying Party on the one hand and of the
Indemnified Party on the other in connection with the statements or omissions
which resulted in such loss, liability, claim, damage, cost or expense as well
as any other relevant equitable considerations. The relative fault of the
Indemnifying Party and of the Indemnified Party shall be determined by reference
to, among other things, whether the untrue or alleged untrue statement of a
material fact or the omission to state a material fact relates to information
supplied or which should have been supplied by the Indemnifying Party or by the
Indemnified Party and the parties' relative intent, knowledge, access to
information and opportunity to correct or prevent such statement or omission.

                  5.7 (a) Upon receipt of any notice from the Company of the
happening of any event requiring the preparation of a supplement or amendment to
a prospectus relating to Registrable Securities so that, as thereafter delivered
to the Holders, such prospectus will not contain an untrue statement of a
material fact or omit to state any material fact required to be stated therein
or necessary to make the statements therein not misleading, each Holder shall
forthwith discontinue disposition of Registrable Securities pursuant to the
registration statement contemplated by Section 5.2 until its receipt of copies
of the supplemented or amended prospectus from the Company and, if so directed
by the Company, each Holder shall deliver to the Company all copies, other than
permanent file copies then in such Holder's possession, of the prospectus
covering such Registrable Securities current at the time of receipt of such
notice.

                           (b) Any Holder which owns five percent (5%) or more
(and with respect to 5.7(b)(ii), "any Holder") of the Company's outstanding
Common Stock shall suspend, upon request of the Company, any disposition of
Registrable Securities pursuant to the

                                       16
<PAGE>   17
Registration Statement and prospectus contemplated by Section 5.2 during (i) any
period not to exceed one 120-day period within any one 12-month period the
Company requires in connection with a primary underwritten offering of equity
securities and (ii) any period, not to exceed two 45-day periods within any
twelve month period, when the Company determines in good faith that offers and
sales pursuant thereto should not be made by reason of the presence of material
undisclosed circumstances or developments with respect to which the disclosure
that would be required in such a prospectus is premature, would have an adverse
effect on the Company or is otherwise inadvisable.

                           (c) As a condition to the inclusion of its
Registrable Securities, each Holder shall furnish to the Company such
information regarding such Holder, the securities of the Company owned
beneficially or of record by such Holder and the distribution proposed by such
Holder as the Company may request in writing or as shall be required in
connection with any registration, qualification or compliance referred to in
this Section V.

                           (d) With respect to any sale of Registrable
Securities pursuant to a Registration Statement filed pursuant to this Section
V, each Holder hereby covenants with the Company (i) not to make any sale of the
Registrable Securities without effectively causing the prospectus delivery
requirements under the Act to be satisfied, and (ii) if such Registrable
Securities are to be sold by any method or in any transaction other than on a
national securities exchange, the Nasdaq National Market, the Nasdaq SmallCap
Market or in the over-the-counter market, in privately negotiated transactions,
or in a combination of such methods, or as otherwise described in the prospectus
contemplated by Section 5.2, to notify the Company at least five (5) business
days prior to the date on which the Holder first offers to sell any such
Registrable Securities.

                           (e) Each Holder acknowledges and agrees that the
Registrable Securities sold pursuant to the Registration Statement described in
this Section are not transferable on the books of the Company unless the stock
certificate submitted to the transfer agent evidencing such Registrable
Securities is accompanied by a certificate reasonably satisfactory to the
Company to the effect that (i) the Registrable Securities have been sold in
accordance with such Registration Statement and (ii) the requirement of
delivering a current prospectus has been satisfied.

                           (f) Each Holder shall not take any action with
respect to any distribution deemed to be made pursuant to such registration
statement, which would constitute a violation of Regulation M under the Exchange
Act or any other applicable rule, regulation or law.

                           (g) At the end of the period during which the Company
is obligated to keep the Registration Statement current and effective as
described above, the Holders of Registrable Securities included in the
Registration Statement and the shares underlying the Placement Warrants shall
discontinue sales of shares pursuant to such Registration Statement upon receipt
of notice from the Company of its intention to remove from registration the
shares covered by such Registration Statement which remain unsold, and such
Holders shall notify the

                                       17
<PAGE>   18
Company of the number of shares registered which remain unsold immediately upon
receipt of such notice from the Company.

                  5.8 With a view to making available to the Holders the
benefits of certain rules and regulations of the SEC which at any time permit
the sale of the Registrable Securities to the public without registration, the
Company shall use its reasonable best efforts:

                           (a) to make and keep public information available, as
those terms are understood and defined in Rule 144 under the Act, at all times;

                           (b) to file with the SEC in a timely manner all
reports and other documents required of the Company under the Exchange Act; and

                           (c) so long as a Holder owns any Registrable
Securities, to furnish to such Holder upon any reasonable request a written
statement by the Company as to its compliance with Rule 144 under the Act, and
of the Exchange Act, and a copy of the most recent annual or quarterly report of
the Company, and such other reports and documents of the Company as such Holder
may reasonably request in availing itself of any rule or regulation of the SEC
allowing a Holder to sell any such securities without registration.

                  5.9 With the written consent of the Company and the Holders
holding at least a majority of the Registrable Securities that are then
outstanding, any provision of this Section V may be waived (either generally or
in a particular instance, either retroactively or prospectively and either for a
specified period of time or indefinitely) or amended. Upon the effectuation of
each such waiver or amendment, the Company shall promptly give written notice
thereof to the Holders, if any, who have not previously received notice thereof
or consented thereto in writing.

VI.      MISCELLANEOUS

                  6.1 Any notice or other communication given hereunder shall be
deemed sufficient in writing and sent by (a) telecopy or facsimile at the
address or number designated below (if delivered on a business day during normal
business hours where such notice is to be received); or (b) registered or
certified mail, return receipt requested, or delivered by hand against written
receipt therefor, addressed to InKine Pharmaceutical Company, Inc., Sentry Park
East, 1720 Walton Road, Blue Bell, PA 19422, Facsimile: (610) 260-9354,
Attention: Robert F. Apple, with a copy to Leerink Swann & Company, 60 State
Street, Boston, MA 02019, Facsimile (617) 918-4955, Attention: Thomas A.
Fitzgerald. Notices shall be deemed to have been given or delivered on the date
of mailing, except notices of change of address, which shall be deemed to have
been given or delivered when received.

                  6.2 Except as set forth in Section 5.9, this Agreement shall
not be changed, modified or amended except by a writing signed by the parties to
be charged, and this Agreement may not be discharged except by performance in
accordance with its terms or by a writing signed by the party to be charged.

                                       18
<PAGE>   19
                  6.3 Upon the execution and delivery of this Agreement by the
Subscriber, this Agreement shall become a binding obligation of the Subscriber
with respect to the purchase of Shares as herein provided, subject to acceptance
by the Company and the Placement Agent; subject, however, to the right hereby
reserved to the Company to enter into the same agreements with other subscribers
and to add and/or delete other persons as subscribers.

                  6.4 (a) Notwithstanding the place where this Agreement may be
executed by any of the parties hereto, the parties expressly agree that all the
terms and provisions hereof shall be construed in accordance with and governed
by the laws of the State of New York without regard to principles of conflicts
of law. In the event that a judicial proceeding is necessary, the sole forum for
resolving disputes arising out of or relating to this Agreement is the Supreme
Court of the State of New York in and for the County of New York or the Federal
Courts for such state and county, and all related appellate courts
(collectively, the "New York Courts"). The parties hereby irrevocably and
unconditionally consent to the jurisdiction of such courts.

                           (b) Each of the parties hereby irrevocably and
unconditionally consents to venue in the New York Courts, and hereby irrevocably
and unconditionally waives any objection to the laying of venue of any judicial
proceeding in the New York Courts, and agrees not to plead or claim in any such
New York Court that any such judicial proceeding brought in any such court has
been brought in an inconvenient forum.

                   6.5 The holding of any provision of this Agreement to be
invalid or unenforceable by a court of competent jurisdiction shall not affect
any other provision of this Agreement, which shall remain in full force and
effect. If any provision of this Agreement shall be declared by a court of
competent jurisdiction to be invalid, illegal or incapable of being enforced in
whole or in part, such provision shall be interpreted so as to remain
enforceable to the maximum extent permissible consistent with applicable law and
the remaining conditions and provisions or portions thereof shall nevertheless
remain in full force and effect and enforceable to the extent they are valid,
legal and enforceable, and no provisions shall be deemed dependent upon any
other covenant or provision unless so expressed herein.

                   6.6 It is agreed that a waiver by either party of a breach of
any provision of this Agreement shall not operate, or be construed, as a waiver
of any subsequent breach by that same party.

                   6.7 The parties agree to execute and deliver all such further
documents, agreements and instruments and take such other and further action as
may be necessary or appropriate to carry out the purposes and intent of this
Agreement.

                   6.8 This Agreement may be executed in two or more
counterparts each of which shall be deemed an original, but all of which shall
together constitute one and the same instrument.

                   6.9 The Subscriber agrees not to issue any public statement
with respect to the

                                       19
<PAGE>   20
Subscriber's investment or proposed investment in the Company or the terms of
any agreement or covenant between them and the Company without the Company's
prior written consent, except such disclosures as may be required under
applicable law or under any applicable order, rule or regulation.

                  6.10 Nothing in this Agreement shall create or be deemed to
create any rights in any person or entity not a party to this Agreement, except
for the holders of Registrable Securities.

                  6.11 Any pronoun herein shall include all genders and/or the
plural or singular as appropriate from the context.

             [The remainder of this page intentionally left blank.]

                                       20
<PAGE>   21
VII.     CONFIDENTIAL INVESTOR QUESTIONNAIRE

                  7.1 The Subscriber represents and warrants that he, she or it
comes within one category marked below, and that for any category marked, he,
she or it has truthfully set forth, where applicable, the factual basis or
reason the Subscriber comes within that category. ALL INFORMATION IN RESPONSE TO
THIS SECTION VII WILL BE KEPT STRICTLY CONFIDENTIAL. The undersigned agrees to
furnish any additional information which the Company deems necessary in order to
verify the answers set forth below.

Category A _____         The undersigned is an individual (not a partnership,
                         corporation, etc.) whose individual net worth, or joint
                         net worth with his or her spouse, presently exceeds
                         $1,000,000.

                                           Explanation. In calculating net worth
                                           you may include equity in personal
                                           property and real estate, including
                                           your principal residence, cash,
                                           short-term investments, stock and
                                           securities. Equity in personal
                                           property and real estate should be
                                           based on the fair market value of
                                           such property less debt secured by
                                           such property.

Category B _____         The undersigned is an individual (not a partnership,
                         corporation, etc.) who had an individual income in
                         excess of $200,000 in each of the two most recent
                         years, or joint income with his or her spouse in excess
                         of $300,000 in each of those years (in each case
                         including foreign income, tax exempt income and full
                         amount of capital gains and losses but excluding any
                         income of other family members and any unrealized
                         capital appreciation) and has a reasonable expectation
                         of reaching the same income level in the current year.

Category C _____         The undersigned is a director or executive officer of
                         the Company.

Category D _____         The undersigned is a bank; a savings and loan
                         association; insurance company; registered investment
                         company; registered business development company;
                         licensed small business investment company or "SBIC";
                         or employee benefit plan within the meaning of Title
                         1 of Employee Retirement Income Security Act or
                         "ERISA" and (a) the investment decision is made by a
                         plan fiduciary which is either a bank, savings and
                         loan association, insurance company or registered
                         investment advisor, or (b) the plan has total assets
                         in excess of $5,000,000 or is a self-directed plan
                         with investment decisions made solely by persons that
                         are accredited investors.

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

                         -------------------------------------------------------
                                            (describe entity)

                                       21
<PAGE>   22
Category E _____           The undersigned is a private business development
                           company as defined in section 202(a)(22) of the
                           Investment Advisors Act of 1940.

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

                           -----------------------------------------------------
                                            (describe entity)

Category F _____           The undersigned is either a corporation, partnership,
                           Massachusetts business trust, or nonprofit
                           organization within the meaning of Section 501(c)(3)
                           of the Internal Revenue Code, in each case not formed
                           for the specific purpose of acquiring the Shares and
                           with total assets in excess of $5,000,000.

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

                           -----------------------------------------------------
                                            (describe entity)

Category G _____           The undersigned is a trust with total assets in
                           excess of $5,000,000, not formed for the specific
                           purpose of acquiring the Shares where the purchase is
                           directed by a "sophisticated person" as defined in
                           Regulation 506(b)(2)(ii) under the Act.

Category H _____           The undersigned hereby certifies that it is an
                           accredited investor because all of its equity owners
                           are accredited investors. The Company, in its sole
                           discretion, may request information regarding the
                           basis on which such equity owners are accredited.

Category I _____           The undersigned hereby certifies that it is an
                           accredited investor because it has total assets in
                           excess of $5,000,000 and was not formed for the
                           specific purpose of acquiring the Shares.

Category J _____           The undersigned is not within any of the categories
                           above and is therefore not an accredited investor.

The Company will notify a prospective Subscriber whether such Subscriber is
eligible to purchase Shares pursuant to this Agreement (and the Company, in its
sole discretion, retains the right to accept or reject all such purchases). The
undersigned agrees that it will notify the Company at any time on or prior to
the Closing Date in the event that the representations and warranties in this
Investor Questionnaire shall cease to be true, accurate and complete.

                                       22
<PAGE>   23
                  7.2      SUITABILITY (please answer each question)

(a) For an individual Subscriber, please describe your current employment,
including the company by which you are employed and its principal business:

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(b) For an individual Subscriber, please describe any college or graduate
degrees held by you:

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(c)  For all Subscribers, please list types of prior investments:

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(d) For all Subscribers, please state whether you have you participated in other
private placements before:

                           YES                                NO
                              -------                           -------

(e) If your answer to question (d) above was "YES", please indicate frequency of
such prior participation in private placements of:

<TABLE>
<CAPTION>
                                                                                        Biotechnology,
                                                                                        Pharmaceutical and
                                    Public                    Private                   Other Life Science
                                    Companies                 Companies                 Companies *
                                    ---------                 ---------                 ------------------
<S>                                                           <C>                       <C>
         Frequently                 ---------                 ---------                 ---------
         Occasionally               ---------                 ---------                 ---------
         Never                      ---------                 ---------                 ---------
</TABLE>

         *indicate how many companies, whether public or private, are in the
          biotechnology, pharmaceutical or other life sciences sectors.

                                       23
<PAGE>   24
(f) For an individual Subscriber, do you expect your current level of income to
significantly decrease in the foreseeable future?

                           YES_______                         NO_______

(g) For trust, corporate, partnership and other institutional Subscribers, do
you expect your total assets to significantly decrease in the foreseeable
future?

                           YES_______                         NO_______

(h) For all Subscribers, do you have any other investments or contingent
liabilities which you reasonably anticipate could cause you to need sudden cash
requirements in excess of cash readily available to you?

                           YES_______                         NO_______

(i) For all Subscribers, are you familiar with the risk aspects and the
non-liquidity of investments such as the securities for which you seek to
subscribe?

                           YES_______                         NO_______

(j) For all Subscribers, do you understand that there is no guarantee of
financial return on this investment and that you run the risk of losing your
entire investment?

                           YES_______                         NO_______

                  7.3      MANNER IN WHICH TITLE IS TO BE HELD. (circle one)

                             (a)    Individual Ownership

                             (b)    Community Property

                             (c)    Joint Tenant with Right of
                                    Survivorship (both parties
                                    must sign)

                             (d)    Partnership*

                             (e)    Tenants in Common

                             (f)    Company*

                             (g)    Trust*

                             (h)    Other

         *If Shares are being subscribed for by an entity, the attached
          Certificate of Signatory must also be completed.

                                       24
<PAGE>   25
                  7.4      NASD AFFILIATION.

Are you affiliated or associated with an NASD member firm (please check one)?

                           YES                       NO
                               ---------                ----------

If Yes, please describe:**

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

         **If Subscriber is a Registered Representative with an NASD member
           firm, have the following acknowledgment signed by the appropriate
           party:

           The undersigned NASD member firm acknowledges receipt of the
           notice required by Article 3, Sections 28(a) and (b) of the Rules
           of Fair Practice.

                                   ---------------------------------------------
                                   Name of NASD Member Firm

                                   By:
                                      ------------------------------------------
                                           Authorized Officer - Signature

                                    --------------------------------------------
                                           Authorized Officer - Printed Name

                                   Date:                             , 2000
                                        -----------------------------

                  7.5      COMPANY RELIANCE ON THIS QUESTIONNAIRE

The undersigned is informed of the significance to the Company of the foregoing
representations and answers contained in this Section VII and such answers have
been provided under the assumption that the Company and its counsel will rely on
them.

                                       25
<PAGE>   26
SIGNATURE PAGE                            DATE SIGNED: APRIL _____ , 2000

NUMBER OF SHARES:                         _______________________

MULTIPLIED BY OFFERING PRICE PER SHARE:   x               $3.80
                                                          -----

EQUALS SUBSCRIPTION AMOUNT:               =               $
                                                          =====

Signature                             Second Signature (if purchasing jointly)

Printed Name                          Printed Second Name

Entity Name                           Entity Name

Address                               Address

City, State and Zip Code              City, State and Zip Code

Telephone-Business                    Telephone--Business

Facsimile-Business                    Facsimile--Business

Tax ID # or Social Security #         Tax ID # or Social Security #

Name in which securities should be issued: ____________________________________

CHECK "YES" IF YOU WOULD LIKE THE SECURITIES TO BE DELIVERED TO YOUR ACCOUNT
WITH LEERINK SWANN & COMPANY OR "NO" IF YOU WOULD LIKE THE SECURITIES TO BE
DELIVERED TO YOUR ADDRESS AS SET FORTH ABOVE.

                               YES _____ NO _____

                                       26
<PAGE>   27
This Subscription Agreement is agreed to and accepted as of April ________,
2000.

                                            INKINE PHARMACEUTICAL COMPANY, INC.

                                            By:

                                            ____________________________________
                                            Name: Robert F. Apple
                                            Title: Chief Financial Officer

                                       27
<PAGE>   28
                            CERTIFICATE OF SIGNATORY

        (To be completed if Shares are being subscribed for by an entity)

                  I,________________________, am the____________________________

of _____________________________________________ (the "Entity").

         I certify that I am empowered and duly authorized by the Entity to
execute and carry out the terms of the Subscription Agreement and to purchase
and hold the Shares, and certify further that the Subscription Agreement has
been duly and validly executed on behalf of the Entity and constitutes a legal
and binding obligation of the Entity.

         IN WITNESS WHEREOF, I have set my hand this___ day of April, 2000.

                                         _______________________________________
                                                       (Signature)

                                       28<PAGE>   1

         THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE
SECURITIES ACT OF 1933, AS AMENDED, OR ANY STATE SECURITIES LAWS AND NEITHER THE
SECURITIES NOR ANY INTEREST THEREIN MAY BE OFFERED, SOLD, TRANSFERRED, PLEDGED
OR OTHERWISE DISPOSED OF EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT
UNDER SUCH ACT OR SUCH LAWS OR AN EXEMPTION FROM REGISTRATION UNDER SUCH ACT AND
SUCH LAWS WHICH, IN THE OPINION OF COUNSEL FOR THIS CORPORATION, IS AVAILABLE.

         VOID AFTER 5:00 P.M. NEW YORK TIME, ON MAY 4, 2005. WARRANT TO PURCHASE
283,887 SHARES OF COMMON STOCK.

PA-40                                                              May 5, 2000

                   WARRANT TO PURCHASE SHARES OF COMMON STOCK
                     OF INKINE PHARMACEUTICAL COMPANY, INC.

         This certifies that Leerink, Swann, Garrity, Sollami, Yaffe & Wynn,
Inc., 60 State St., 15th Floor, Boston, MA 02109, or any subsequent holder of
this Warrant (the "HOLDER"), for value received, is entitled, subject to the
adjustment and to the other terms set forth below, to purchase from InKine
Pharmaceutical Company, Inc., a New York corporation (the "COMPANY"), 283,887
fully paid and nonassessable shares of the Company's common stock, par value
$0.0001 per share (the "COMMON STOCK") at a price of $5.13 per share (the
"EXERCISE PRICE"). This Warrant shall be exercisable at any time on or after the
date first noted above, (the "COMMENCEMENT DATE") but not later than 5:00 p.m.
(New York Time) on the Expiration Date (as defined below). The Exercise Price
and, in some cases, the number of shares purchasable hereunder are subject to
adjustment as provided in Section 3 of this Warrant. This Warrant and all rights
hereunder, to the extent not exercised in the manner set forth herein shall
terminate and become null and void on the Expiration Date. "EXPIRATION DATE"
means 5:00 p.m. (New York time) on May 4, 2005. In the event that the Holder
does not exercise this Warrant pursuant to the terms of this Warrant, then this
Warrant shall expire, be cancelled, and be null and void. Pursuant to the letter
agreement, dated February 28, 2000, between the Company and the Holder, the
Holder has agreed to act as placement agent in connection with a certain private
placement of the Company's securities which closed on the date hereof (the
"OFFERING").

This Warrant is subject to the following terms and conditions:

1.       Exercise; Issuance of Certificates; Payment for Shares; Conversion
         Right.

         1.1 Duration of Exercise of Warrant. This Warrant is exercisable at the
option of the Holder at any time or from time to time but not earlier than on
the Commencement Date or later than 5:00 p.m. (New York Time) on the Expiration
Date for all or a portion of the shares of Common Stock which may be purchased
hereunder (the "WARRANT SHARES"). 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, with the Subscription Agreement attached hereto duly
<PAGE>   2
completed and executed and, unless the Conversion Right in Section 1.2 is
exercised, upon payment of the Exercise Price for the number of Warrant Shares
for which this Warrant is being exercised determined in accordance with the
provisions hereof. The Company agrees that the Warrant Shares shall be and are
deemed to be issued to the Holder as the record owner of such shares as of the
close of business on the date on which this Warrant shall have been surrendered
and payment made for such shares. Subject to the provisions of Section 2,
certificates for the shares of Common Stock so purchased, together with any
other securities or property to which the Holder is entitled upon such exercise,
shall be delivered to the Holder by the Company or its transfer agent at the
Company's expense within a reasonable time after the rights represented by this
Warrant have been exercised, but not later than ten (10) days from the date of
such exercise. Each stock certificate so delivered shall be in such
denominations of Common Stock as may be requested by the Holder and shall be
registered in the name of the Holder or such other name as shall be designated
by the Holder. If, upon exercise of this Warrant, fewer than all of the Warrant
Shares evidenced by this Warrant are purchased prior to the Expiration Date of
this Warrant, one or more new warrants substantially in the form of, and on the
terms in, this Warrant will be issued for the remaining number of shares of
Common Stock not purchased upon exercise of this Warrant. 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.

         1.2 Conversion Right. At any time during the term of this Warrant, the
Holder may, at its option, convert this Warrant, in whole or in part (a
"CONVERSION RIGHT"), into the number of shares of Common Stock determined in
accordance with this Section 1.2, by surrendering this Warrant at the principal
office of the Company or at the office of its stock transfer agent, accompanied
by a notice, in the form attached, stating such Holder's intent to effect such
Conversion Right, the number of Warrant Shares to be exchanged and the date on
which the Holder requests that such Conversion Right occur (the "NOTICE OF
CONVERSION"). The Conversion Right shall take place on the date specified in the
Notice of Conversion or, if later, the date the Notice of Conversion is received
by the Company (the "CONVERSION DATE"). Certificates for the shares issuable
upon such Conversion Right 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 Conversion Date and delivered to the Holder within seven (7)
days following the Conversion Date. In connection with any Conversion Right,
this Warrant shall represent the right to subscribe for and acquire the number
of Warrant Shares equal to (i) the number of Warrant Shares specified by the
Holder in its Notice of Conversion (the "CONVERSION AMOUNT") less (ii) the
number of Warrant Shares equal to the quotient obtained by dividing (a) the
product of the Conversion Amount and the then current Exercise Price by (b) the
then current Market Price (as defined in Section 3.2 hereafter) of a share of
Common Stock.

                                       2
<PAGE>   3
2.       Shares to Be Fully Paid; Reservation of Shares.

         The Company covenants and agrees that all Warrant Shares shall, upon
issuance and payment therefor, if any, be duly authorized, validly issued, fully
paid and nonassessable and free from all preemptive rights of any stockholder
and free of all taxes, liens and charges with respect to the issue thereof. The
Company covenants that it will reserve and keep available a sufficient number of
shares of its authorized but unissued Common Stock for such exercise. The
Company will take all such reasonable action as may be necessary to assure that
such Warrant Shares may be issued as provided herein without violation of any
applicable law or regulation, or of any requirements of the Nasdaq SmallCap
Market or any other domestic securities exchange or automated quotation system
upon which the Common Stock may be listed.

3.       Adjustment of Exercise Price and Number of Shares.

         The Exercise Price and, in some cases, the number of shares purchasable
upon the exercise of this Warrant shall be subject to adjustment from time to
time upon the occurrence of certain events described in this Section 3.

         3.1 Split or Combination of Common Stock and Stock Dividend. In case
the Company shall at any time subdivide, redivide, recapitalize, split or change
its outstanding shares of Common Stock into a greater number of shares or
declare a dividend upon its Common Stock payable solely in shares of Common
Stock, the Exercise Price in effect immediately prior to such subdivision or
declaration shall be proportionately reduced, and the number of Warrant Shares
issuable upon exercise of this Warrant shall be proportionately increased.
Conversely, in case the outstanding shares of Common Stock of the Company shall
be combined into a smaller number of shares, the Exercise Price in effect
immediately prior to such combination shall be proportionately increased, and
the number of Warrant Shares issuable upon exercise of this Warrant shall be
proportionately reduced.

         3.2 Definitions. For purposes of this Agreement, the following
definitions shall apply:

                  (a) "Market Price" shall mean: (i) if there is a ready public
         market of registered stock, the Market Price shall be the "Stock Price"
         (as defined in this Section 3.2) obtained by taking the average over a
         period of five (5) consecutive trading days ending on the second
         trading day prior to the date of determination; and (ii) if there is no
         ready public market, Market Price shall be the higher of the last bona
         fide sale made by the Company and the fair market value of the Common
         Stock as determined by the Board of Directors in its good faith
         judgment.

                  (b) "Stock Price" shall mean (i) the last sales price, on each
         such trading day, of a share of Common Stock, or if no such sale takes
         place on any such trading day, the mean of the highest bid and lowest
         asked prices therefor on any such trading day, in each case as
         officially reported on all national securities

                                       3
<PAGE>   4
             exchanges on which the Common Stock is then listed or admitted to
             trading or as reported by the National Association of Securities
             Dealers Automated Quotation System ("NASDAQ"), or (ii) if the
             Common Stock is not then listed or admitted to trading on any
             national securities exchange or in the over-the-counter market, as
             reported by NASDAQ, the closing price of the Common Stock on such
             date, or (iii) if the Common Stock is not then quoted by NASDAQ,
             the mean between the highest and lowest bid prices reported by
             market makers and dealers for the Common Stock listed as such by
             the National Quotation Bureau, Incorporated, or any similar
             successor organization, or (iv) if there is no ready public market,
             then the Stock Price shall be the Market Price, as determined
             pursuant to 3.2(a)(ii) above.

         3.3 Notice of Adjustment. Promptly after adjustment of the Exercise
Price or any increase or decrease in the number of shares purchasable upon the
exercise of this Warrant, the Company shall give written notice thereof, by
first class mail, postage prepaid, addressed to the registered Holder of this
Warrant at the address of such Holder as shown on the books of the Company. The
notice shall be signed by the Company's Chairman or President and shall state
the effective date of the adjustment and the Exercise Price resulting from such
adjustment and the increase or decrease, if any, in the number of shares
purchasable at such price upon the exercise of this Warrant, setting forth in
reasonable detail the method of calculation and the facts upon which such
calculation is based.

         3.4 Notices. If at any time:

                  (a) the Company shall declare any cash dividend upon its
         Common Stock;

                  (b) the Company shall declare any dividend upon its Common
         Stock payable in securities (other than a dividend payable solely in
         shares of Common Stock) or make any special dividend or other
         distribution to the holders of its Common Stock;

                  (c) there shall be any consolidation or merger of the Company
         with another corporation, or a sale of all or substantially all of the
         Company's assets to another corporation; or

                  (d) there shall be a voluntary or involuntary dissolution,
         liquidation or winding-up of the Company;

then, in any one or more of said cases, the Company shall give, by certified or
registered mail, return receipt requested, postage prepaid, addressed to the
registered Holder of this Warrant at the address of such Holder as shown on the
books of the Company, (i) at least thirty (30) days' prior written notice of the
date on which the books of the Company shall close or a record shall be taken
for such dividend, distribution or subscription rights or for determining rights
to vote in respect of any such dissolution, liquidation or winding-up; (ii) at
least ten (10) days' prior written

                                       4
<PAGE>   5
notice of the date on which the books of the Company shall close or a record
shall be taken for determining rights to vote in respect of any such
reorganization, reclassification, consolidation, merger or sale, and (iii) in
the case of any such reorganization, reclassification, consolidation, merger,
sale, dissolution, liquidation or winding-up, at least thirty (30) days' written
notice of the date when the same shall take place. Any notice given in
accordance with clause (i) above shall also specify, in the case of any such
dividend, distribution or option rights, the date on which the holders of Common
Stock shall be entitled thereto. Any notice given in accordance with clause
(iii) above shall also specify the date on which the holders of Common Stock
shall be entitled to exchange their Common Stock for securities or other
property deliverable upon such reorganization, reclassification, consolidation,
merger, sale, dissolution, liquidation or winding- up, as the case may be. If
the registered Holder of this Warrant does not exercise this Warrant prior to
the occurrence of an event described above, except as provided in Sections 3.1
and 3.5, the Holder shall not be entitled to receive the benefits accruing to
existing holders of the Common Stock in such event. Notwithstanding anything
herein to the contrary, if and to the extent the Holder chooses to exercise this
Warrant within the ten (10) day period following receipt of the notice specified
in clause (ii) above, the Holder may elect to pay the aggregate Exercise Price
by delivering to the Company cash or a cashier's check in the amount of the
aggregate par value of the shares of Common Stock to be purchased and the
Holder's full recourse promissory note in the amount of the balance of the
aggregate Exercise Price, which promissory note shall be payable to the order of
the Company in a single sum on the 30th day following the date of receipt of
such notice and shall bear interest at the lowest applicable federal short term
rate (using monthly compounding) as established pursuant to Section 1274(d) of
the Internal Revenue Code of 1986, as amended, or any successor provision;
provided, however, that if the Holder elects to deliver such a promissory note
to the Company, the Holder will pledge to the Company all Common Stock issued in
connection with the exercise of this Warrant, and the Company shall retain
possession of the certificates evidencing such Common Stock, until such time as
the Note is paid in full.

         3.5 Changes in Common Stock. In case at any time following the
Commencement Date hereof, the Company shall be a party to any transaction
(including, without limitation, a merger, consolidation, sale of all or
substantially all of the Company's assets or recapitalization of the Common
Stock) in which the previously outstanding Common Stock shall be changed into or
exchanged for different securities of the Company or common stock or other
securities of another corporation or interests in a noncorporate entity or other
property (including cash) or any combination of any of the foregoing (each such
transaction being herein called the "TRANSACTION" and the date of consummation
of the Transaction being herein called the "CONSUMMATION DATE"), then, as a
condition of the consummation of the Transaction, lawful and adequate provisions
shall be made so that the Holder, upon the exercise hereof at any time on or
after the Consummation Date, shall be entitled to receive, and this Warrant
shall thereafter represent the right to receive, in lieu of the Common Stock
issuable upon such exercise prior to the Consummation Date, the highest amount
of securities or other property to which such Holder would actually have been
entitled as a stockholder upon the consummation of the Transaction if such
Holder had exercised such Warrant immediately prior thereto. The provisions of
this Section 3.5 shall similarly apply to successive Transactions.

                                       5
<PAGE>   6
4.       Issue Tax.

         The issuance of certificates for shares of Common Stock upon the
exercise of this Warrant shall be made without charge to the Holder of this
Warrant for any issue tax in respect thereof; provided, however, that the
Company shall not be required to pay any tax which may be payable in respect of
any transfer involved in the issuance and delivery of any certificate in a name
other than that of the then Holder of this Warrant.

5.       No Voting or Dividend Rights; Limitation of Liability.

         Nothing contained in this Warrant shall be construed as conferring upon
the Holder hereof the right to vote or to consent or to receive notice as a
stockholder in respect of meetings of stockholders for the election of directors
of the Company or any other matters or any rights whatsoever as a stockholder of
the Company. Except for the adjustment to the Exercise Price pursuant to Section
3.1 in the event of a dividend on the Common Stock payable in shares of Common
Stock, no dividends or interest shall be payable or accrued in respect of this
Warrant or the interest represented hereby or the shares purchasable hereunder
until, and only to the extent that, this Warrant shall have been exercised. No
provisions hereof, in the absence of affirmative action by the Holder to
purchase shares of Common Stock, and no mere enumeration herein of the rights or
privileges of the Holder hereof, shall give rise to any liability of such Holder
for the Exercise Price or as a stockholder of the Company whether such liability
is asserted by the Company or by its creditors.

6.       Restrictions on Transferability of Securities; Compliance With
         Securities Act.

         6.1 Restrictions on Transferability. This Warrant and the Warrant
Shares shall not be transferable in the absence of registration under the
Securities Act of 1933, as amended (the "SECURITIES ACT") or an applicable
exemption from registration thereunder.

         6.2 Restrictive Legend. Each certificate representing the Warrant
Shares or any other securities issued in respect of the Warrant Shares upon any
stock split, stock dividend, recapitalization, merger, consolidation or similar
event, shall be stamped or otherwise imprinted with a legend substantially in
the following form (in addition to any legend required under applicable state
securities laws):

         "THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR ANY STATE SECURITIES
LAWS AND NEITHER THE SECURITIES NOR ANY INTEREST THEREIN MAY BE OFFERED, SOLD,
TRANSFERRED, PLEDGED OR OTHERWISE DISPOSED OF EXCEPT PURSUANT TO AN EFFECTIVE
REGISTRATION STATEMENT UNDER SUCH ACT OR SUCH LAWS OR AN EXEMPTION FROM
REGISTRATION UNDER SUCH ACT AND SUCH LAWS WHICH, IN THE OPINION OF COUNSEL FOR
THE HOLDER, WHICH COUNSEL AND OPINION ARE REASONABLY SATISFACTORY TO COUNSEL FOR
THIS CORPORATION, IS AVAILABLE."

                                       6
<PAGE>   7
7.       Registration Rights.

         7.1 As used in this Warrant, the following terms shall have the
following meanings:

                           (a) "Affiliate" shall mean, with respect to any
                  Person (as defined below), any other Person controlling,
                  controlled by, or under direct or indirect common control
                  with, such Person (for the purposes of this definition
                  "control," when used with respect to any specified Person,
                  shall mean the power to direct the management and policies of
                  such person, directly or indirectly, whether through ownership
                  of voting securities, by contract or otherwise; and the terms
                  "controlling" and "controlled" shall have meanings correlative
                  to the foregoing).

                           (b) "Business Day" shall mean a day, Monday through
                  Friday, on which banks are generally open for business in each
                  of New York, New York; Boston, Massachusetts; and
                  Philadelphia, Pennsylvania;

                           (c) "Person" shall mean any person, individual,
                  corporation, limited liability company, partnership, trust or
                  other nongovernmental entity or any governmental agency,
                  court, authority or other body (whether foreign, federal,
                  state, local or otherwise).

                           (d) The terms "register," "registered" and
                  "registration" refer to the registration effected by preparing
                  and filing with the SEC a registration statement in compliance
                  with the Act, and the declaration or ordering by the SEC of
                  the effectiveness of such registration statement.

                           (e) "Registrable Securities" shall mean the shares of
                  Common Stock issuable upon the exercise of this Warrant;
                  provided, however, that securities shall only be treated as
                  Registrable Securities if and only for so long as they (A)
                  have not been disposed of pursuant to a registration statement
                  declared effective by the SEC, (B) have not been sold in a
                  transaction exempt from the registration and prospectus
                  delivery requirements of the Act so that all transfer
                  restrictions and restrictive legends with respect thereto are
                  removed upon the consummation of such sale, and (C) are held
                  by the Holder.

                           (f) "Registration Expenses" shall mean all expenses
                  incurred by the Company in complying with this Section 7
                  including, without limitation, all registration, qualification
                  and filing fees, printing expenses, escrow fees, fees and
                  expenses of counsel for the Company, blue sky fees and
                  expenses and the expense of any special audits incident to, or
                  required by, any such registration (but excluding the fees of
                  legal counsel for the Holder).

                           (g) "Registration Statement" shall have the meaning
                  ascribed to such term in Section 7.2 (a).

                                       7
<PAGE>   8
                           (h) "Registration Period" shall have the meaning
                  ascribed to such term in Section 7.4(a).

                           (i) "Selling Expenses" shall mean all underwriting
                  discounts and selling commissions applicable to the sale of
                  Registrable Securities and the aggregate fees and expenses of
                  legal counsel for the Holder.

         7.2 The Company shall, as soon as practicable, but not later than ten
(10) business days after the date hereof (such tenth business day herein
referred to as the "Filing Date"), (i) use its best efforts to file with the SEC
a registration statement (the "Registration Statement") with respect to the
resale of the Registerable Securities and use its best efforts to have such
Registration Statement declared effective by the SEC as soon thereafter as is
practical and (ii) cause such Registration Statement to remain effective until
the earlier of such date as the Holder has completed the distribution described
in the Registration Statement and such time as such Shares are no longer, by
reason of Rule 144 (k) under the Act, required to be registered for the sale
thereof by the Holder. If requested by the Holder, and in accordance with
applicable securities laws, the Registration Statement shall cover the direct
sale of such Registrable Securities to the Holder of such securities.

         7.3 All Registration Expenses incurred in connection with any
registration, qualification, exemption or compliance pursuant to Section 7.2
shall be borne by the Company. All Selling Expenses relating to the sale of
securities registered by or on behalf of the Holder shall be borne by the
Holder.

         7.4 In the case of the registration, qualification, exemption or
compliance effected by the Company pursuant to this Agreement, the Company
shall, upon reasonable request, inform the Holder as to the status of such
registration, qualification, exemption and compliance. At its expense the
Company shall:

                           (a) use its best efforts to keep such registration,
                  and any qualification, exemption or compliance under state
                  securities laws which the Holder reasonably requests the
                  Company to obtain, continuously effective until the Holder has
                  completed the distribution described in the registration
                  statement relating thereto. The period of time during which
                  the Company is required hereunder to keep the Registration
                  Statement effective is referred to herein as "the Registration
                  Period."

                           (b) advise the Holder:

                                    (i) when the Registration Statement or any
                           amendment thereto has been filed with the SEC and
                           when the Registration Statement or any post-effective
                           amendment thereto has become effective;

                                       8
<PAGE>   9
                                    (ii) of any request by the SEC for
                           amendments or supplements to the Registration
                           Statement or the prospectus included therein or for
                           additional information;

                                    (iii) of the issuance by the SEC of any stop
                           order suspending the effectiveness of the
                           Registration Statement or the initiation of any
                           proceedings for such purpose;

                                    (iv) of the receipt by the Company of any
                           notification with respect to the suspension of the
                           qualification of the Registrable Securities included
                           therein for sale in any jurisdiction or the
                           initiation or threatening of any proceeding for such
                           purpose; and

                                    (v) of the happening of any event that
                           requires the making of any changes in the
                           Registration Statement or the prospectus so that, as
                           of such date, the statements therein are not
                           misleading and do not omit to state a material fact
                           required to be stated therein or necessary to make
                           the statements therein (in the case of the
                           prospectus, in the light of the circumstances under
                           which they were made) not misleading;

                           (c) make every reasonable effort to obtain the
                  withdrawal of any order suspending the effectiveness of any
                  Registration Statement at the earliest possible time;

                           (d) furnish to the Holder, without charge, at least
                  one copy of such Registration Statement and any post-effective
                  amendment or supplement thereto, including financial
                  statements and schedules, and, if the Holder so requests in
                  writing, all exhibits (excluding those incorporated by
                  reference) in the form filed with the SEC;

                           (e) during the Registration Period, deliver to the
                  Holder, without charge, a reasonable number of copies of the
                  prospectus included in such Registration Statement and any
                  amendment or supplement thereto as the Holder may reasonably
                  request; and the Company consents to the use, consistent with
                  the provisions hereof, of the prospectus and any amendment or
                  supplement thereto by the Holder of Registrable Securities in
                  connection with the offering and sale of the Registrable
                  Securities covered by the prospectus and any amendment or
                  supplement thereto;

                           (f) cooperate with the Holder to facilitate the
                  timely preparation and delivery of certificates representing
                  Registrable Securities to be sold pursuant to any Registration
                  Statement free of any restrictive legends to the extent not
                  required at such time and in such denominations and registered
                  in such names as the Holder may request at least five (5)
                  business days prior to sales of Registrable Securities
                  pursuant to such Registration Statement;

                                       9
<PAGE>   10
                           (g) upon the occurrence of any event contemplated by
                  Section 7.4(b)(v) above, the Company shall promptly prepare a
                  post-effective amendment to the Registration Statement or a
                  supplement to the related prospectus, or file any other
                  required document so that, as thereafter delivered to
                  purchasers of the Registrable Securities included therein, the
                  prospectus will not include any untrue statement of a material
                  fact or omit to state any material fact necessary to make the
                  statements therein, in the light of the circumstances under
                  which they were made, not misleading.

         7.5 The Holder shall have no right to take any action to restrain,
enjoin or otherwise delay any registration pursuant to Section 7.2 hereof as a
result of any controversy that may arise with respect to the interpretation or
implementation of this Agreement.

         7.6              (a) Upon receipt of any notice from the Company
                  of the happening of any event requiring the preparation of a
                  supplement or amendment to a prospectus relating to
                  Registrable Securities so that, as thereafter delivered to THE
                  Holder, such prospectus will not contain an untrue statement
                  of a material fact or omit to state any material fact required
                  to be stated therein or necessary to make the statements
                  therein not misleading, each Holder shall forthwith
                  discontinue disposition of Registrable Securities pursuant to
                  the registration statement contemplated by Section 7.2 until
                  its receipt of copies of the supplemented or amended
                  prospectus from the Company and, if so directed by the
                  Company, each Holder shall deliver to the Company all copies,
                  other than permanent file copies then in such Holder's
                  possession, of the prospectus covering such Registrable
                  Securities current at the time of receipt of such notice.

                           (b) As a condition to the inclusion of its
                  Registrable Securities, the Holder shall furnish to the
                  Company such information regarding the Holder, the securities
                  of the Company owned beneficially or of record by the Holder
                  and the distribution proposed by the Holder as the Company may
                  request in writing or as shall be required in connection with
                  any registration, qualification or compliance referred to in
                  this Section 7.

                           (c) With respect to any sale of Registrable
                  Securities pursuant to a Registration Statement filed pursuant
                  to this Section 7, the Holder hereby covenants with the
                  Company (i) not to make any sale of the Registrable Securities
                  without effectively causing the prospectus delivery
                  requirements under the Act to be satisfied, and (ii) if such
                  Registrable Securities are to be sold by any method or in any
                  transaction other than on a national securities exchange, the
                  Nasdaq National Market, the Nasdaq SmallCap Market or in the
                  over-the-counter market, in privately negotiated transactions,
                  or in a combination of such methods, or as otherwise described
                  in the prospectus contemplated by Section 7.2, to notify the

                                       10
<PAGE>   11
                  Company at least five (5) business days prior to the date on
                  which the Holder first offers to sell any such Registrable
                  Securities.

                           (d) The Holder acknowledges and agrees that the
                  Registrable Securities sold pursuant to the Registration
                  Statement described in this Section are not transferable on
                  the books of the Company unless the stock certificate
                  submitted to the transfer agent evidencing such Registrable
                  Securities is accompanied by a certificate reasonably
                  satisfactory to the Company to the effect that (i) the
                  Registrable Securities have been sold in accordance with such
                  Registration Statement and (ii) the requirement of delivering
                  a current prospectus has been satisfied.

                           (e) The Holder shall not take any action with respect
                  to any distribution deemed to be made pursuant to such
                  registration statement, which would constitute a violation of
                  Regulation M under the Exchange Act or any other applicable
                  rule, regulation or law.

                           (f) At the end of the period during which the Company
                  is obligated to keep the Registration Statement current and
                  effective as described above, the Holder of Registrable
                  Securities included in the Registration Statement and the
                  shares underlying the Warrants shall discontinue sales of
                  shares pursuant to such Registration Statement upon receipt of
                  notice from the Company of its intention to remove from
                  registration the shares covered by such Registration Statement
                  which remain unsold, and such Holder shall notify the Company
                  of the number of shares registered which remain unsold
                  immediately upon receipt of such notice from the Company.

         7.7 With the written consent of the Company and the Holder, any
provision of this Section 7 may be waived (either generally or in a particular
instance, either retroactively or prospectively and either for a specified
period of time or indefinitely) or amended.

8.       Modification and Waiver.

         This Warrant and any provision hereof may be changed, waived,
discharged or terminated only by an instrument in writing signed by the party
against which enforcement of the same is sought.

9.       Notices.

         Except as otherwise provided herein, any notice, request or other
document required or permitted to be given or delivered to the Holder hereof or
the Company shall be delivered personally or by nationally recognized overnight
courier service or sent by registered or certified mail, return receipt
requested, to such Holder at its address as shown on the books of the Company or
to the Company at its principal office. Notices delivered personally shall be
effective upon receipt, notices sent by overnight courier service shall be
deemed to have been

                                       11
<PAGE>   12
received one (1) day after deposit with such courier and notices sent by United
States mail shall be deemed to have been received three (3) days after deposit
with the U.S. Postal Service.

10.      Descriptive Headings and Governing Law.

         The descriptive headings of the several sections and paragraphs of this
Warrant are inserted for convenience only and do not constitute a part of this
Warrant. This Warrant shall be construed and enforced in accordance with, and
the rights of the parties shall be governed by, the laws of the State of New
York without giving effect to conflict of laws. The parties hereby submit to the
exclusive jurisdiction of the courts of the State of New York located in New
York County and the federal courts located in the Southern District of New York,
with respect to any action or legal proceeding commenced by either party with
respect to this Agreement. Each party irrevocably waives any objection it now
has or hereafter may have respecting the venue of any such action or proceeding
or the inconvenience of such forum, and each party consents to the service of
process in any such action or proceeding in the manner set forth for the
delivery of notices herein.

11.      Lost Warrants or Stock Certificate.

         The Company represents and warrants to the Holder that upon receipt of
evidence reasonably satisfactory to the Company of the loss, theft, destruction
or mutilation of any Warrant or stock certificate and, in the case of any such
loss, theft or destruction, and if requested, upon receipt of an indemnity bond
reasonably satisfactory to the Company, or in the case of any such mutilation,
upon surrender and cancellation of such Warrant or stock certificate, the
Company at its expense will make and deliver a new Warrant or stock certificate,
of like tenor, in lieu of the lost, stolen, destroyed or mutilated Warrant or
stock certificate.

12.      Fractional Shares.

         No fractional shares shall be issued upon exercise of this Warrant. The
Company shall, in lieu of issuing any fractional share pay the Holder entitled
to such fraction a sum in cash equal to the fair market value of any such
fractional interest as it shall appear on the public market, or if there is no
public market for such shares, then as shall be reasonably determined by the
Company.

                                       12
<PAGE>   13
         IN WITNESS WHEREOF, the Company has caused this Warrant to be executed
by its officer, thereunto duly authorized as of this 5th day of May, 2000.

                                     INKINE PHARMACEUTICAL COMPANY, INC.

                                     By:      /s/Robert F. Apple
                                         --------------------------------------
                                              Robert F. Apple
                                              Senior Vice President and
                                              Chief Financial Officer
<PAGE>   14
                                SUBSCRIPTION FORM

                     To Be Executed by the Registered Holder
                          in Order to Exercise Warrants

[DATE]

InKine Pharmaceutical Company, Inc.
Sentry Park East
1720 Walton Road
Blue Bell, Pennsylvania  19422

Attention:

                  The undersigned, the holder of the within Warrant, hereby
irrevocably elects to exercise the purchase right represented by such Warrant
for, and to purchase thereunder, ____________ shares of Common Stock, par value
$.0001 per share (the "Common Stock") of InKine Pharmaceutical Company, Inc.
and, subject to the following paragraph, herewith makes payment of
_________________ Dollars ($__________) therefor and requests that the
certificates for such shares be issued in the name of, and delivered to
_______________________________________, whose address is
_______________________________________, ______________________________________
and if such number of shares of Common Stock shall not represent all of the
shares of Common Stock which may be exercised pursuant to the Warrant, a new
Warrant for the balance of such shares of Common Stock shall be registered in
the name of, and delivered to, the Registered Holder at the address set forth
below.

         If the exercise of this Warrant is not covered by a registration
statement effective under the Securities Act of 1933, as amended (the
"Securities Act"), the undersigned represents that it is acquiring such Common
Stock for investment for its own account, not as nominee or agent, and not with
a view to the distribution thereof and the undersigned has not signed or
otherwise arranged for the selling, granting any participation in, or otherwise
distributing the same.

                            Leerink, Swann, Garrity, Sollami, Yaffe & Wynn, Inc.

DATED:_______________       By:_______________________________________
                                        Authorized Signature

                            Name:_____________________________________
                            Title:______________________________________
<PAGE>   15
                         CONVERSION RIGHT EXERCISE FORM

                     To Be Executed by the Registered Holder
                    in Order to Exercise the Conversion Right

         The undersigned hereby irrevocably elects to surrender its Warrant for
such shares of Common Stock pursuant to the Conversion Right of the within
Warrant, as provided for in Section 1.2 of such Warrant.

         Please issue a certificate or certificates for such Common Stock in the
name of

            PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER

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

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

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

                    ----------------------------------------
                     [please print or type name and address]

and deliver to

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

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

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

                    ----------------------------------------
                     [please print or type name and address]

and if such number of Warrants shall not be all the Warrants evidenced by the
attached Warrant a new Warrant for the balance of such Warrants shall be
registered in the name of, and delivered to, the Registered Holder at the
address stated below.

Dated:
       ----------------------------     X
                                          ------------------------------------

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

                                          ------------------------------------
                                          Address

                                          ------------------------------------
                                          Taxpayer Identification Number
<PAGE>   16
                                   ASSIGNMENT

                     To Be Executed by the Registered Holder
                           in Order to Assign Warrants

FOR VALUE RECEIVED,                        hereby sells, assigns and transfers
unto

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

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

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

                    ----------------------------------------
                     [please print or type name and address]

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

            PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER

                        of the Warrants represented by the attached Warrant, and
hereby irrevocably constitutes and appoints                 attorney to transfer
the attached Warrant and the Warrants represented thereby on the books of the
Company, with full power of substitution in the premises.

Dated:                     Leerink, Swann, Garrity, Sollami, Yaffe & Wynn, Inc.

                           By:
                              -------------------------------------------------
                                        Authorized Signature

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

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