<PAGE>   1
                                                                     Exhibit 4.1











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                          STOCKHOLDERS RIGHTS AGREEMENT


                            Dated as of July 27, 1995


                                     between


                                   ALTEON INC.


                                       and


                         Registrar and Transfer Company


                                 as Rights Agent



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                                       1
<PAGE>   2
                                                                     Exhibit 4.1

                                TABLE OF CONTENTS

Certain Definitions............................................................1

Appointment of Rights Agent...................................................10

Issue of Rights and Right Certificates........................................10

Form of Right Certificates....................................................11

Execution, Countersignature and Registration..................................12

Transfer, Split-Up, Combination and Exchange of Right Certificates;
         Mutilated, Destroyed, Lost or Stolen Right Certificates;
         Uncertificated Rights................................................13

Exercise of Rights; Expiration Date of Rights.................................14

Cancellation and Destruction of Right Certificates............................16

Reservation and Availability of Preferred Shares..............................16

Preferred Shares Record Date..................................................18

Adjustments in Rights After there is an Acquiring Person; Exchange
         of Rights for Shares; Business Combinations..........................18

Certain Adjustments...........................................................22

Certificate of Adjustment.....................................................24

Additional Covenants..........................................................24

Fractional Rights and Fractional Shares.......................................24

Rights of Action..............................................................25

Transfer and Ownership of Rights and Right Certificates.......................26

Right Certificate Holder Not Deemed a Stockholder.............................26

Concerning the Rights Agent...................................................27

Merger or Consolidation or Change of Rights Agent.............................27

Duties of Rights Agent........................................................28

Change of Rights Agent........................................................31

Issuance of Additional Rights and Right Certificates..........................32

Redemption and Termination....................................................32

Notices.......................................................................33

Supplements and Amendments....................................................34

                                       2
<PAGE>   3
                                                                     Exhibit 4.1

Successors....................................................................34

Benefits of Rights Agreement; Determinations and Actions by the
     Board of Directors, etc..................................................35

Severability..................................................................35

Governing Law.................................................................36

Counterparts; Effectiveness...................................................36

Descriptive Headings..........................................................36





                                       3
<PAGE>   4
                                                                     Exhibit 4.1

         STOCKHOLDERS RIGHTS AGREEMENT (this "Rights Agreement") dated as of
July 27, 1995, between ALTEON INC., a Delaware corporation (the "Company"), and
Registrar and Transfer Company, as Rights Agent (the "Rights Agent").

         The Board of Directors of the Company has authorized and declared a
dividend of one Right (as hereinafter defined) for each share of Common Stock,
par value $0.01 per share, of the Company (the "Common Stock") outstanding at
the Close of Business (as hereinafter defined) on the date fifteen (15) days
following the date of this Rights Agreement (the "Record Date"), and has
authorized the issuance of one Right (as such number may hereafter be adjusted
pursuant to the provisions of this Rights Agreement) with respect to each share
of Common Stock that shall become outstanding between the Record Date and the
earliest of the Distribution Date, the Redemption Date or the Expiration Date
(as such terms are hereinafter defined); provided, however, that Rights may be
issued with respect to shares of Common Stock that shall become outstanding
after the Distribution Date and prior to the earlier of the Redemption Date or
the Expiration Date in accordance with the provisions of Section 23. Each Right
shall initially represent the right to purchase one one-thousandths (1/1,000ths)
of a share of Series F Preferred Stock, par value $0.01 per share, of the
Company (the "Preferred Shares"), having the powers, rights and preferences set
forth in the Certificate of Designation attached as Exhibit A.

         Accordingly, in consideration of the premises and the mutual agreements
herein set forth, the parties hereby agree as follows:

         Section 1. Certain Definitions. For purposes of this Rights Agreement,
the following terms have the meanings indicated:

                  "Acquiring Person" shall mean any Person who or which, alone
or together with all Affiliates and Associates of such Person, shall be the
Beneficial Owner of more than 20% of the Common Shares then outstanding, other
than pursuant to a Qualifying Offer, but shall not include (a) the Company, any
Subsidiary of the Company, any employee benefit plan of the Company or of any of
its Subsidiaries, or any Person holding Common Shares for or pursuant to the
terms of any such employee benefit plan or (b) any such Person who has become
such a Beneficial Owner solely because (i) of a change in the aggregate number
of Common Shares outstanding since the last date on which such Person acquired
Beneficial Ownership of any Common Shares or (ii) it acquired such Beneficial
Ownership in the good faith belief that such acquisition would not (x) cause
such Beneficial Ownership to exceed 20% of the Common Shares then outstanding
and such Person relied in good faith in computing the percentage of its
Beneficial Ownership on publicly filed reports or documents of the Company which
are inaccurate or out-of-date or (y) otherwise cause a Distribution Date or the
adjustment provided for in Section 11(a) to occur. Notwithstanding clause (b) of
the prior sentence, if any Person that is not an Acquiring Person due to such
clause (b) does not reduce its percentage of Beneficial Ownership of Common
Shares to 20% or less by the Close of Business on the fifth Business Day after
notice from the Company (the date of notice being the first day) that such
Person's Beneficial Ownership of Common Shares so exceeds 20%, such Person
shall, at the end of such five Business Day period, become an Acquiring Person
(and such clause (b) shall no longer apply to such Person). For purposes of this
definition, the determination whether any Person acted in "good faith" shall be
conclusively determined by the Board of Directors of the Company, acting by a
vote of those directors of the Company whose approval would be required to
redeem the Rights under Section 24.

                                       1
<PAGE>   5
                                                                     Exhibit 4.1

                  "Affiliate" and "Associate", when used with reference to any
Person, shall have the respective meanings ascribed to such terms in Rule 12b-2
of the General Rules and Regulations under the Exchange Act, as in effect on the
date of this Rights Agreement.

                  A Person shall be deemed the "Beneficial Owner" of, and shall
be deemed to "beneficially own", and shall be deemed to have "Beneficial
Ownership" of, any securities:

                  (i) which such Person or any of such Person's Affiliates or
Associates is deemed to "beneficially own" within the meaning of Rule 13d-3 of
the General Rules and Regulations under the Exchange Act, as in effect on the
date of this Rights Agreement;

                  (ii) which such Person or any of such Person's Affiliates or
Associates has (A) the right to acquire (whether such right is exercisable
immediately or only after the passage of time) pursuant to any agreement,
arrangement or understanding (written or oral), or upon the exercise of
conversion rights, exchange rights, rights (other than the Rights), warrants or
options, or otherwise; provided, however, that a Person shall not be deemed the
Beneficial Owner of, or to beneficially own, or to have Beneficial Ownership of,
securities tendered pursuant to a tender or exchange offer made by or on behalf
of such Person or any of such Person's Affiliates or Associates until such
tendered securities are accepted for purchase or exchange thereunder, or (B) the
right to vote pursuant to any agreement, arrangement or understanding (written
or oral); provided, however, that a Person shall not be deemed the Beneficial
owner of, or to beneficially own, any security if (1) the agreement, arrangement
or understanding (written or oral) to vote such security arises solely from a
revocable proxy or consent given to such Person in response to a public proxy or
consent solicitation made pursuant to, and in accordance with, the applicable
rules and regulations under the Exchange Act and (2) the beneficial ownership of
such security is not also then reportable on Schedule 13D under the Exchange Act
(or any comparable or successor report); or

                  (iii) which are beneficially owned, directly or indirectly, by
any other Person with which such Person or any of such Person's Affiliates or
Associates has any agreement, arrangement or understanding (written or oral) for
the purpose of acquiring, holding, voting (except pursuant to a revocable proxy
as described in clause (ii)(B) of this definition) or disposing of any
securities of the Company.

         Notwithstanding the foregoing, nothing contained in this definition
shall cause a Person ordinarily engaged in business as an underwriter of
securities to be the "Beneficial Owner" of, or to "beneficially own", any
securities acquired in a bona fide firm commitment underwriting pursuant to an
underwriting agreement with the Company.

                  "Book Value", when used with reference to Common Shares issued
by any Person, shall mean the amount of equity of such Person applicable to each
Common Share, determined (i) in accordance with generally accepted accounting
principles in effect on the date as to which such Book Value is to be
determined, (ii) using all the consolidated assets and all the consolidated
liabilities of such Person on the date as of which such Book Value is to be
determined, except that no value shall be included in such assets for goodwill
arising from consummation of a business combination, and (iii) after giving
effect to (A) the exercise of all rights, options and warrants to purchase such
Common Shares (other than the Rights), and the conversion of all securities
convertible into such Common


                                       2
<PAGE>   6
                                                                     Exhibit 4.1

Shares, at an exercise or conversion price, per Common Share, which is less than
such Book Value before giving effect to such exercise or conversion (whether or
not exercisability or convertibility is conditioned upon occurrence of a future
event), (B) all dividends and other distributions on the capital stock of such
Person declared prior to the date as of which such Book Value is to be
determined and to be paid or made after such date, and (C) any other agreement,
arrangement or understanding (written or oral), or transaction or other action
prior to the date as of which such Book Value is to be determined which would
have the effect of thereafter reducing such Book Value.

                  "Business Combination" shall have the meaning set forth in
Section 11(c)(I).

                  "Business Day" shall mean each Monday, Tuesday, Wednesday,
Thursday and Friday which is not a day on which banking institutions in the
Borough of Manhattan, the City of New York, are authorized or obligated by law
or executive order to close.

                  "Certificate of Designation" shall mean the Certification of
Designation of Series F Preferred Stock setting forth the powers, preferences,
rights, qualifications, limitations and restrictions of such series of Preferred
Stock of the Company, a copy of which is attached as Exhibit A.

                  "Close of Business" on any given date shall mean 5:00 p.m.,
New York City time, on such date; provided, however, that, if such date is not a
Business Day, "Close of Business" shall mean 5:00 p.m., New York City time, on
the next succeeding Business Day.

                  "Common Shares", when used with reference to the Company prior
to a Business Combination, shall mean the shares of Common Stock of the Company
or any other shares of capital stock of the Company into which the Common Stock
shall be reclassified or changed. "Common Shares", when used with reference to
any Person (other than the Company prior to a Business Combination), shall mean
shares of capital stock of such Person (if such Person is a corporation) of any
class or series, or units of equity interests in such Person (if such Person is
not a corporation) of any class or series, the terms of which do not limit (as a
maximum amount and not merely in proportional terms) the amount of dividends or
income payable or distributable on such class or series or the amount of assets
distributable on such class or series upon any voluntary or involuntary
liquidation, dissolution or winding up of such Person and do not provide that
such class or series is subject to redemption at the option of such Person, or
any shares of capital stock or units of equity interests into which the
foregoing shall be reclassified or changed; provided, however, that, if any time
there shall be more than one such class or series of capital stock or equity
interests of such Person, "Common Shares" of such Person shall include all such
classes and series substantially in the proportion of the total number of shares
or other units of each such class or series outstanding at such time.

                  "Common Stock" shall have the meaning set forth in the
introductory paragraph of this Rights Agreement.

                  "Company" shall have the meaning set forth in the heading of
this Rights Agreement; provided, however, that if there is a Business
Combination, "Company" shall have the meaning set forth in Section 11(c)(III).

                  The term "control" with respect to any Person shall mean the
power to direct the management and policies of such Person, directly or
indirectly, by or


                                       3
<PAGE>   7
                                                                     Exhibit 4.1

through stock ownership, agency or otherwise, or pursuant to or in connection
with an agreement, arrangement or understanding (written or oral) with one or
more other Persons by or through stock ownership, agency or otherwise; and the
terms "controlling" and "controlled" shall have meanings correlative to the
foregoing.

                  "Distribution Date" shall have the meaning set forth in
Section 3(b).

                  "Exchange Act" shall mean the Securities Exchange Act of 1934,
as in effect on the date in question, unless otherwise specifically provided.

                  "Exchange Consideration" shall have the meaning set forth in
Section 11(b)(I).

                  "Expiration Date" shall have the meaning set forth in Section
7(a).

                  "Major Part," when used with reference to the assets of the
Company and its Subsidiaries as of any date, shall mean assets (i) having a fair
market value aggregating 50% or more of the total fair market value of all the
assets of the Company and its Subsidiaries (taken as a whole) as of the date in
question, (ii) accounting for 50% or more of the total value (net of
depreciation and amortization) of all the assets of the Company and its
Subsidiaries (taken as a whole) as would be shown on a consolidated or combined
balance sheet of the Company and its Subsidiaries as of the date in question,
prepared in accordance with generally accepted accounting principles then in
effect, or (iii) accounting for 50% or more of the total amount of earnings
before interest, taxes, depreciation and amortization or revenues of the Company
and its Subsidiaries (taken as a whole) as would be shown on, or derived from, a
consolidated or combined statement of income of the Company and its Subsidiaries
for the period of 12 months ending on the last day of the Company's monthly
accounting period next preceding the date in question, prepared in accordance
with generally accepted accounting principles then in effect.

                  "Market Value," when used with reference to Common Shares on
any date, shall be deemed to be the average of the daily closing prices, per
share, of such Common Shares for the period which is the shorter of (1) 30
consecutive Trading Days immediately prior to the date in question or (2) the
number of consecutive Trading Days beginning on the Trading Day immediately
after the date of the first public announcement of the event requiring a
determination of the Market Value and ending on the Trading Day immediately
prior to the record date of such event; provided, however, that, in the event
that the Market Value of such Common Shares is to be determined in whole or in
part during a period following the announcement by the issuer of such Common
Shares of any action of the type described in Section 12(a) that would require
an adjustment thereunder, then, and in each such case, the Market Value of such
Common Shares shall be appropriately adjusted to reflect the effect of such
action on the market price of such Common Shares. The closing price for each
Trading Day shall be the closing price quoted on the composite tape for
securities listed on the New York Stock Exchange, or, if such securities are not
quoted on such composite tape or if such securities are not listed on such
exchange, on the principal United States securities exchange registered under
the Exchange Act (or any recognized foreign stock exchange) on which such
securities are listed, or, if such securities are not listed on any such
exchange, the average of the closing bid and asked quotations with respect to a
share of such securities on the National Association of Securities Dealers, Inc.
Automated Quotations System ("NASDAQ") or such other system then in use, or if
no such quotations are available, the average of the closing bid and asked
prices as furnished by a professional market maker making a market in such
securities selected by the Board of Directors of


                                       4
<PAGE>   8
                                                                     Exhibit 4.1

the Company. If on any such Trading Day no market maker is making a market in
such securities, the closing price of such securities on such Trading Day shall
be deemed to be the fair value of such securities as determined in good faith by
the Board of Directors of the Company (whose determination shall be described in
a statement filed with the Rights Agent and shall be binding on the Rights
Agent, the holders of Rights and all other Persons); provided, however, that for
the purpose of determining the closing price of the Preferred Shares for any
Trading Day on which there is no such market maker for the Preferred Shares the
closing price on such Trading Day shall be deemed to be the Formula Number (as
defined in the Certificate of Designation) times the closing price of the Common
Shares of the Company on such Trading Day.

                  "Person" shall mean an individual, corporation, partnership,
joint venture, association, trust, unincorporated organization or other entity.

                  "Preferred Shares" shall have the meaning set forth in the
introductory paragraph of this Rights Agreement. Any reference in this Rights
Agreement to Preferred Shares shall be deemed to include any authorized fraction
of a Preferred Share, unless the context otherwise requires.

                  "Principal Party" shall mean the Surviving Person in a
Business Combination; provided, however, that, if such Surviving Person is a
direct or indirect Subsidiary of any other Person, "Principal Party" shall mean
the Person which is the ultimate parent of such Surviving Person and which is
not itself a Subsidiary of another Person. In the event ultimate control of such
Surviving Person is shared by two or more Persons, "Principal Party" shall mean
that Person that is immediately controlled by such two or more Persons.

                  "Purchase Price" with respect to each Right shall mean $80.00,
as such amount may from time to time be adjusted as provided herein, and shall
be payable in lawful money of the United States of America. All references
herein to the Purchase Price shall mean the Purchase Price as in effect at the
time in question.

                  "Qualifying Offer" shall mean an all-cash tender offer made by
any Person for all outstanding Common Shares which meets all of the following
requirements:

         (1) on or prior to the date such offer is commenced within the meaning
         of Rule 14d-2(a) of the General Rules and Regulations under the
         Exchange Act, such Person has, and has provided to the Company, firm
         written commitments from responsible financial institutions, which have
         been accepted by such Person (or one of its Affiliates), to provide,
         subject only to customary terms and conditions, funds for such offer
         which, when added to the amount of cash and cash equivalents which such
         Person then has available and has irrevocably committed in writing to
         the Company to utilize for purposes of such offer, will be sufficient
         to pay for all Common Shares outstanding on a fully diluted basis
         pursuant to the offer and the second-step transaction required by
         clause (6) below and all related expenses, together with copies of all
         written materials prepared by such person for such financial
         institutions in connection with obtaining such financing commitments;

         (2) after the consummation of such offer, such Person, alone or
         together with any of its Affiliates and Associates, owns Common Shares
         representing a majority of the then outstanding Common Shares;

                                       5
<PAGE>   9
                                                                     Exhibit 4.1

         (3) such offer remains open for at least 45 Business Days; provided,
         however, that (x) if there is any increase in the price of such offer,
         such offer must remain open for at least an additional 20 Business Days
         after the last such increase, (y) such offer must remain open for at
         least 20 Business Days after the date that any bona fide alternative
         offer is made which, in the opinion of one or more investment banking
         firms designated by the Company, provides for consideration per share
         in excess of that provided for in such offer, and (z) such offer must
         remain open for at least 20 Business Days after the date on which such
         Person reduces the per share price offered in accordance with clause
         (6)(y) below; provided further, however, that such offer need not
         remain open, as a result of this clause (3), beyond (i) the time which
         any other offer satisfying the criteria for a Qualifying Offer is then
         required to be kept open under this clause (3), or (ii) the scheduled
         expiration date, as such date may be extended by public announcement on
         or prior to the then scheduled expiration date, of any other tender or
         exchange offer for Common Shares with respect to which the Board of
         Directors has agreed to redeem the Rights immediately prior to
         acceptance for payment of Common Shares thereunder (unless such other
         offer is terminated prior to its expiration without any Common Shares
         having been purchased thereunder);

         (4) such offer is accompanied by a written opinion, in customary form,
         of a nationally recognized investment banking firm which is addressed
         to the holders of Common Shares other than such Person and states that
         the price to be paid to holders pursuant to the offer is fair from a
         financial point of view to such holders and includes any written
         presentation of such firm showing the analysis and range of values
         underlying such conclusions;

         (5) such offer is approved by a majority of the Board of Directors of
         the Company who are not officers of the Company and who are not
         nominees, Affiliates or Associates of such Person, after determining
         that the price to be paid to stockholders pursuant to the offer is the
         best value reasonably available to stockholders after taking into
         account the potential long-term value of the Company and all other
         factors that it considers relevant or otherwise in the best interest of
         the stockholders; and

         (6) prior to or on the date that such offer is commenced within the
         meaning of Rule 14d-2(a) of the General Rules and Regulations under the
         Exchange Act, such Person makes an irrevocable written commitment to
         the Company (x) to consummate a transaction or transactions promptly
         upon the completion of such offer, whereby all Common Shares not
         purchased in such offer will be acquired at the same price per share
         paid in such offer, subject only to the condition that the Board of
         Directors shall have granted any approvals required to enable such
         Person to consummate such transaction or transactions following
         consummation of such offer without obtaining the vote of any other
         stockholder, (y) that such Person will not make any amendment to the
         original offer which reduces the per share price offered (other than a
         reduction to reflect any dividend declared by the Company after the
         commencement of such offer, whether by way of recapitalization,
         reorganization, repurchase or otherwise), changes the form of
         consideration offered, or reduces the number of shares being sought or
         which is in any other respect materially adverse to the Company's
         stockholders, and (z) that neither such Person nor of any its
         Affiliates or Associates will make any offer for any equity securities
         of the Company for a period of six months after the commencement of the
         original offer if such original offer does not result in the tender of
         the


                                       6
<PAGE>   10
                                                                     Exhibit 4.1

         number of Common Shares required to be purchased pursuant to clause (2)
         above, unless another tender offer by another party for all outstanding
         Common Shares is commenced that (a) constitutes a Qualifying Offer or
         (b) is approved by the Board of Directors of the Company (in which
         event, any new offer by such Person or of any of its Affiliates or
         Associates must be at a price no less than that provided for in such
         approved offer).

                  "Record Date" shall have the meaning set forth in the
introductory paragraph of this Rights Agreement.

                  "Redemption Date" shall have the meaning set forth in Section
24(a).

                  "Redemption Price" with respect to each Right shall mean $.01,
as such amount may from time to time be adjusted in accordance with Section 12.
All references herein to the Redemption Price shall mean the Redemption Price as
in effect at the time in question.

                  "Registered Common Shares" shall mean Common Shares which are,
as of the date of consummation of a Business Combination, and have continuously
been for the 12 months immediately preceding such date, registered under Section
12 of the Exchange Act.

                  "Right Certificate" shall mean a certificate evidencing a
Right in substantially the form attached as Exhibit B.

                  "Rights" shall mean the rights to purchase Preferred Shares
(or other securities) as provided in this Rights Agreement.

                  "Securities Act" shall mean the Securities Act of 1933, as in
effect on the date in question, unless otherwise specifically provided.

                  "Subsidiary" shall mean a Person, at least a majority of the
total outstanding voting power (being the power under ordinary circumstances
(and not merely upon the happening of a contingency) to vote in the election of
directors of such Person (if such Person is a corporation) or to participate in
the management and control of such Person (if such Person is not a corporation))
of which is owned, directly or indirectly, by another Person or by one or more
other Subsidiaries of such other Person or by such other Person and one or more
other Subsidiaries of such other Person.

                  "Surviving Person" shall mean (1) the Person which is the
continuing or surviving Person in a consolidation or merger specified in Section
11(c)(I)(i) or 11(c)(I)(ii) or (2) the Person to which the Major Part of the
assets of the Company and its Subsidiaries is sold, leased, exchanged or
otherwise transferred or disposed of in a transaction specified in Section
11(c)(I)(iii); provided, however, that if the Major Part of the assets of the
Company and its Subsidiaries is sold, leased, exchanged or otherwise transferred
or disposed of in one or more related transactions specified in Section
11(c)(I)(iii) to more than one Person, the "Surviving Person" in such case shall
mean the Person that acquired assets of the Company and/or its Subsidiaries with
the greatest fair market value in such transaction or transactions.

                  "Trading Day" shall mean a day on which the principal national
securities exchange (or principal recognized foreign stock exchange, as the case
may be) on which any securities or Rights, as the case may be, are listed or
admitted to trading is open for the transaction of business or, if the
securities or Rights in question are not listed or admitted to trading on any
national


                                       7
<PAGE>   11
                                                                     Exhibit 4.1

securities exchange (or recognized foreign stock exchange, as the case
may be), a Business Day.

         SECTION 2. Appointment of Rights Agent. The Company hereby appoints the
Rights Agent to act as agent for the Company in accordance with the terms and
conditions hereof, and the Rights Agent hereby accepts such appointment. The
Company may from time to time appoint one or more co-Rights Agents as it may
deem necessary or desirable (the term "Rights Agent" being used herein to refer,
collectively, to the Rights Agent together with any such co-Rights Agents). In
the event the Company appoints one or more co-Rights Agents, the respective
duties of the Rights Agent and any co-Rights Agents shall be as the Company
shall determine.

         SECTION 3. Issue of Rights and Right Certificates. (a) One Right shall
be associated with each Common Share outstanding on the Record Date, each
additional Common Share that shall become outstanding between the Record Date
and the earliest of the Distribution Date, the Redemption Date or the Expiration
Date and each additional Common Share with which Rights are issued after the
Distribution Date but prior to the earlier of the Redemption Date or the
Expiration Date as provided in Section 23; provided, however, that, if the
number of outstanding Rights are combined into a smaller number of outstanding
Rights pursuant to Section 12(a), the appropriate fractional Right determined
pursuant to such Section shall thereafter be associated with each such Common
Share.

                  (b) Until the earlier of (i) such time as the Company learns
that a Person has become an Acquiring Person or (ii) the Close of Business on
such date, if any, as may be designated by the Board of Directors of the Company
following the commencement of, or first public disclosure of an intent to
commence, a tender or exchange offer by any Person (other than the Company, any
Subsidiary of the Company, any employee benefit plan of the Company or of any of
its Subsidiaries, or any Person holding Common Shares for or pursuant to the
terms of any such employee benefit plan and other than a Qualifying Offer) for
outstanding Common Shares, if upon consummation of such tender or exchange offer
such Person could be the Beneficial Owner of more than 20% of the outstanding
Common Shares (the Close of Business on the earlier of such dates being the
"Distribution Date"), (x) the Rights will be evidenced by the certificates for
Common Shares registered in the names of the holders thereof and not by separate
Right Certificates and (y) the Rights, including the right to receive Right
Certificates, will be transferable only in connection with the transfer of
Common Shares. As soon as practicable after the Distribution Date, the Rights
Agent will send, by first-class, postage-prepaid mail, to each record holder of
Common Shares as of the Distribution Date, at the address of such holder shown
on the records of the Company, a Right Certificate evidencing one whole Right
for each Common Share (or for the number of Common Shares with which one whole
Right is then associated if the number of Rights per Common Share held by such
record holder has been adjusted in accordance with the proviso in Section 3(a)).
If the number of Rights associated with each Common Share has been adjusted in
accordance with the proviso in Section 3(a), at the time of distribution of the
Right Certificates the Company may make any necessary and appropriate rounding
adjustments so that Right Certificates representing only whole numbers of Rights
are distributed and cash is paid in lieu of any fractional Right in accordance
with Section 15(a). As of and after the Distribution Date, the Rights will be
evidenced solely by such Right Certificates.

                  (c) With respect to any certificate for Common Shares, until
the earliest of the Distribution Date, the Redemption Date or the Expiration
Date, the Rights associated with the Common Shares represented by any such
certificate


                                       8
<PAGE>   12
                                                                     Exhibit 4.1

shall be evidenced by such certificate alone, the registered holders of the
Common Shares shall also be the registered holders of the associated Rights and
the surrender for transfer of any such certificate shall also constitute the
transfer of the Rights associated with the Common Shares represented thereby.

                  (d) Certificates issued for Common Shares after the Record
Date (including, without limitation, upon transfer or exchange of outstanding
Common Shares), but prior to the earliest of the Distribution Date, the
Redemption Date or the Expiration Date, may have printed on, written on or
otherwise affixed to them the following legend:

         This certificate also evidences and entitles the holder hereof to
         certain Rights as set forth in a Stockholders Rights Agreement dated as
         of July 27, 1995, as it may be amended from time to time (the "Rights
         Agreement"), between Alteon Inc. (the "Company") and Registrar and
         Transfer Company, as Rights Agent (the "Rights Agent"), the terms of
         which are hereby incorporated herein by reference and a copy of which
         is on file at the principal executive offices of the Company. Under
         certain circumstances, as set forth in the Rights Agreement, such
         Rights will be evidenced by separate certificates and will no longer be
         evidenced by this certificate. The Rights Agent will mail to the holder
         of this certificate a copy of the Rights Agreement without charge after
         receipt of a written request therefor. Rights beneficially owned by
         Acquiring Persons or their Affiliates or Associates (as such terms are
         defined in the Rights Agreement) and by any subsequent holder of such
         Rights are null and void and nontransferable.

         Notwithstanding this paragraph (d), the omission of a legend shall not
affect the enforceability of any part of this Rights Agreement or the rights of
any holder of Rights.

         SECTION 4. Form of Right Certificates. The Right Certificates (and the
form of election to purchase and form of assignment to be printed on the reverse
side thereof) shall be in substantially the form set forth as Exhibit B and may
have such marks of identification or designation and such legends, summaries or
endorsements printed thereon as the Company may deem appropriate and as are not
inconsistent with the provisions of this Rights Agreement, or as may be required
to comply with any applicable law or with any rule or regulation made pursuant
thereto or with any rule or regulation of any stock exchange on which the Rights
may from time to time be listed, or to conform to usage. Subject to the
provisions of Sections 7, 11 and 23, the Right Certificates, whenever issued,
shall be dated as of the Distribution Date, and on their face shall entitle the
holders thereof to purchase such number of Preferred Shares as shall be set
forth therein for the Purchase Price set forth therein, subject to adjustment
from time to time as herein provided.

         SECTION 5.  Execution, Countersignature and Registration.

                  (a) The Right Certificates shall be executed on behalf of the
Company by the Chairman of the Board, the Chief Executive Officer, the
President, the Chief Operating Officer, the Treasurer or a Vice President
(whether preceded by any additional title) of the Company, either manually or by
facsimile signature, and have affixed thereto the Company's seal or a facsimile
thereof which shall be attested by the Secretary, an Assistant Secretary or a
Vice President (whether preceded by any additional title, provided that such
Vice President shall not have also executed the Right Certificates) of the
Company,


                                       9
<PAGE>   13
                                                                     Exhibit 4.1

 either manually or by facsimile signature. The Right Certificates shall
be manually countersigned by the Rights Agent and shall not be valid or
obligatory for any purpose unless so countersigned. In case any officer of the
Company who shall have signed any of the Right Certificates shall cease to be
such an officer of the Company before countersignature by the Rights Agent and
issuance and delivery by the Company, such Right Certificates may nevertheless
be countersigned by the Rights Agent and issued and delivered by the Company
with the same force and effect as though the person who signed such Right
Certificates had not ceased to be such an officer of the Company; and any Right
Certificate may be signed on behalf of the Company by any person who, at the
actual date of execution of such Right Certificate, shall be a proper officer of
the Company to sign such Right Certificate, although at the date of execution of
this Rights Agreement any such person was not such an officer of the Company.

                  (b) Following the Distribution Date, the Rights Agent will
keep or cause to be kept, at its principal office in Cranford, New Jersey, books
for registration and transfer of the Right Certificates issued hereunder. Such
books shall show the names and addresses of the respective holders of the Right
Certificates, the number of Rights evidenced by each of the Right Certificates,
the certificate number of each of the Right Certificates and the date of each of
the Right Certificates.

         SECTION 6. Transfer, Split-Up, Combination and Exchange of Right
Certificates; Mutilated, Destroyed, Lost or Stolen Right Certificates;
Uncertificated Rights.

                  (a) Subject to the provisions of Sections 7(e) and 15, at any
time after the Distribution Date, and at or prior to the Close of Business on
the earlier of the Redemption Date or the Expiration Date, any Right Certificate
or Right Certificates may be transferred, split-up, combined or exchanged for
another Right Certificate or Right Certificates representing, in the aggregate,
the same number of Rights as the Right Certificate or Right Certificates
surrendered then represented. Any registered holder desiring to transfer,
split-up, combine or exchange any Right Certificate shall make such request in
writing delivered to the Rights Agent and shall surrender the Right Certificate
or Right Certificates to be transferred, split-up, combined or exchanged at the
principal office of the Rights Agent; provided, however, that neither the Rights
Agent nor the Company shall be obligated to take any action whatsoever with
respect to the transfer of any Right Certificate surrendered for transfer until
the registered holder shall have completed and signed the certification
contained in the form of assignment on the reverse side of such Right
Certificate and shall have provided such additional evidence of the identity of
the Beneficial Owner (or former Beneficial Owner) or Affiliates or Associates
thereof as the Company shall reasonably request. Thereupon the Rights Agent
shall, subject to Sections 7(e) and 15, countersign and deliver to the Person
entitled thereto a Right Certificate or Right Certificates, as the case may be,
as so requested. The Company may require payment of a sum sufficient to cover
any tax or governmental charge that may be imposed in connection with any
transfer, split-up, combination or exchange or Right Certificates.

                  (b) Upon receipt by the Company and the Rights Agent of
evidence reasonable satisfactory to them of the loss, theft, destruction or
mutilation of a valid Right Certificate, and, in case of loss, theft or
destruction, of indemnity or security reasonably satisfactory to them, and, at
the Company's request, reimbursement to the Company and the Rights Agent of all
reasonable expenses incidental thereto, and upon surrender to the Rights Agent
and cancellation of the Right Certificate if mutilated, the Company will make a
new


                                       10
<PAGE>   14
                                                                     Exhibit 4.1

Right Certificate of like tenor and deliver such new Right Certificate to the
Rights Agent for delivery to the registered owner in lieu of the Right
Certificate so lost, stolen, destroyed or mutilated.

                  (c) Notwithstanding any other provision hereof, the Company
and the Rights Agent may amend this Rights Agreement to provide for
uncertificated Rights in addition to or in place of Rights evidenced by Right
Certificates.


                                       11
<PAGE>   15
                                                                     Exhibit 4.1

         SECTION 7.  Exercise of Rights; Expiration Date of Rights.

                  (a) Subject to Section 7(e) and except as otherwise provided
herein (including Section 11), each Right shall entitle the registered holder
thereof, upon exercise thereof as provided herein, to purchase for the Purchase
Price, at any time after the Distribution Date and at or prior to the earlier of
(i) the Close of Business on the 10th anniversary of the date of this Rights
Agreement (the Close of Business on such date being the "Expiration Date"), or
(ii) the Redemption Date, one one-thousandths (1/1,000ths) of a Preferred Share,
subject to adjustment from time to time as provided in Sections 11 and 12.

                  (b) The registered holder of any Right Certificate may
exercise the Rights evidenced thereby (except as otherwise provided herein) in
whole or in part at any time after the Distribution Date, upon surrender of the
Right Certificate, with the form of election to purchase on the reverse side
thereof duly executed, to the Rights Agent at the principal office of the Rights
Agent in New York, New York, together with payment of the Purchase price for
each one one-thousandths (1/1,000ths) of a Preferred Share as to which the
Rights are exercised, at or prior to the earlier of (i) the Expiration Date or
(ii) the Redemption Date.

                  (c) Upon receipt of a Right Certificate representing
exercisable Rights, with the form of election to purchase duly executed,
accompanied by payment of the Purchase Price for the Preferred Shares to be
purchased together with an amount equal to any applicable transfer tax, in
lawful money of the United States of America, in cash or by certified check or
money order payable to the order of the Company, the Rights Agent shall
thereupon (i) either (A) promptly requisition from any transfer agent of the
Preferred Shares (or make available, if the Rights Agent is the transfer agent)
certificates for the number of Preferred Shares to be purchased and the Company
hereby irrevocably authorizes its transfer agent to comply with all such
requests or (B) if the Company shall have elected to deposit the Preferred
Shares with a depositary agent under the depositary arrangement, promptly
requisition from the depositary agent depositary receipts representing the
number of one one-thousandths (1/1,000ths) of a Preferred Share to be purchased
(in which case certificates for the Preferred Shares to be represented by such
receipts shall be deposited by the transfer agent with the depositary agent) and
the Company will direct the depositary agent to comply with all such requests,
(ii) when appropriate, promptly requisition from the Company the amount of cash
to be paid in lieu of issuance of fractional shares in accordance with Section
15, (iii) promptly after receipt of such certificates or depositary receipts,
cause the same to be delivered to or upon the order of the registered holder of
such Right Certificate, registered in such name or names as may be designated by
such holder and (iv) when appropriate, after receipt promptly deliver such cash
to or upon the order of the registered holder of such Right Certificate.

                  (d) In case the registered holder of any right Certificate
shall exercise fewer than all the Rights evidenced thereby, a new Right
Certificate evidencing Rights equivalent to the Rights remaining unexercised
shall be issued by the Rights Agent and delivered to the registered holder of
such Right Certificate or to his duly authorized assigns, subject to the
provisions of Section 15.

                  (e) Notwithstanding anything in this Rights Agreement to the
contrary, any Rights that are at any time beneficially owned by an Acquiring
Person or any Affiliate or Associate of an Acquiring Person shall be null and
void and nontransferable, and any holder of any such Right (including any

                                       12
<PAGE>   16
                                                                     Exhibit 4.1

purported transferee or subsequent holder) shall not have any right to exercise
or transfer any such Right.

                  (f) Notwithstanding anything in this Rights Agreement to the
contrary, neither the Rights Agent nor the Company shall be obligated to
undertake any action with respect to a registered holder of any Right
Certificates upon the occurrence of any purported exercise as set forth in this
Section 7 unless such registered holder shall have (i) completed and signed the
certificate contained in the form of election to purchase set forth on the
reverse side of the Right Certificate surrendered for such exercise and (ii)
provided such additional evidence of the identity of the Beneficial Owner (or
former Beneficial owner) or Affiliates or Associates thereof as the Company
shall reasonably request.

                  (g) The Company may temporarily suspend, for a period of time
not to exceed 90 calendar days after the Distribution Date, the exercisability
of the Rights in order to prepare and file a registration statement under the
Securities Act, on appropriate form, with respect to the Preferred Shares
purchasable upon exercise of the Rights and permit such registration statement
to become effective; provided, however, that no such suspension shall remain
effective after, and the Rights shall without any further action by the Company
or any other Person become exercisable immediately upon, the effectiveness of
such registration statement. Upon any such suspension, the Company shall issue a
public announcement stating that the exercisability of the Rights has been
temporarily suspended and shall issue a further public announcement at such time
as the suspension is no longer in effect. Notwithstanding any provision herein
to the contrary, the Rights shall not be exercisable in any jurisdiction if the
requisite qualification under the blue sky or securities laws of such
jurisdiction shall not have been obtained or the exercise of the Rights shall
not be permitted under applicable law.

         SECTION 8.  Cancellation and Destruction of Right Certificates.

         All Right Certificates surrendered or presented for the purpose of
exercise, transfer, split-up, combination or exchange shall, and any Right
Certificate representing Rights that have become null and void and
nontransferable pursuant to Section 7(e) surrendered or presented for any
purpose shall, if surrendered or presented to the Company or to any of its
agents, be delivered to the Rights Agent for cancellation or in canceled form,
or, if surrendered or presented to the Rights Agent, for cancellation and
retirement, and the Rights Agent for cancellation and retirement, and the Rights
Agent shall be canceled by it, and no Right Certificates shall be issued in lieu
thereof except as expressly permitted by this Rights Agreement. The Company
shall deliver to the Rights Agent shall so cancel and retire, any Right
Certificate purchased or acquired by the Company. The Rights Agent shall deliver
all canceled Right Certificates to the Company, or shall, at the written request
of the Company, destroy such canceled Right Certificates, and in such case shall
deliver a certificate of destruction thereof to the Company.

         SECTION 9.  Reservation and Availability of Preferred Shares.

                  (a) The Company covenants and agrees that it will cause to be
reserved and kept available out of its authorized and unissued Preferred shares
or any authorized and issued Preferred Shares held in its treasury, free from
preemptive rights or any right of first refusal, a number of Preferred Shares
sufficient to permit the exercise in full of all outstanding Rights.

                                       13
<PAGE>   17
                                                                     Exhibit 4.1

                  (b) In the event that there shall not be sufficient Preferred
Shares issued but not outstanding or authorized but unissued to permit the
exercise or exchange or Rights in accordance with Section 11, the Company
covenants and agrees that it will take all such action as may be necessary to
authorize additional Preferred Shares for issuance upon the exercise or exchange
of Rights pursuant to Section 11; provided, however, that if the Company is
unable to cause the authorization of additional Preferred Shares, then the
Company shall, or in lieu of seeking any such authorization, the Company may, to
the extent necessary and permitted by applicable law and any agreements or
instruments in effect prior to the Distribution Date to which it is a party, (A)
upon surrender of a Right, pay cash equal to the Purchase Price in lieu of
issuing Preferred Shares and requiring payment therefor, (B) upon due exercise
of a Right and payment of the Purchase Price for each Preferred Share as to
which such Right is exercised, issue equity securities having a value equal to
the value of the Preferred Shares which otherwise would have been issuable
pursuant to Section 11, which value shall be determined by a nationally
recognized investment banking firm selected by the Board or (C) upon due
exercise of a Right and payment of the Purchase Price for each Preferred Share
as to which such Right is exercised, distribute a combination of Preferred
Shares, case and/or other equity and/or debt securities having an aggregate
value equal to the value of the Preferred Shares which otherwise would have been
issuable pursuant to Section 11, which value shall be determined by a nationally
recognized investment banking firm selected by the Board. To the extent that any
legal or contractual restrictions (pursuant to agreements or instruments in
effect prior to the Distribution Date to which it is a party) prevent the
Company from paying the full amount payable in accordance with the forgoing
sentence, the Company shall pay to holders of the Rights as to which such
payments are being made all amounts which are not then restricted on a pro rata
basis as such payments become permissible under such legal or contractual
restrictions until such payments have been paid in full.

                  (c) The Company covenants and agrees that it will take all
such action as may be necessary to ensure that all Preferred Shares delivered
upon exercise or exchange of Rights shall, at the time of delivery of the
certificates for such preferred Shares (subject to payment of the Purchase
Price), be duly and validly authorized and issued and fully paid and
nonassessable shares.

                  (d) So long as the Preferred Shares issuable upon the exercise
or exchange of Rights are to be listed on any national securities exchange, the
Company covenants and agrees to use its best efforts to cause, from and after
such time as the Rights become exercisable or exchangeable, all Preferred Shares
reserved for such issuance to be listed on such securities exchange upon
official notice of issuance upon such exercise or exchange.

                  (e) The Company further covenants and agrees that it will pay
when due and payable any and all Federal and state transfer taxes and charges
which may be payable in respect of the issuance or delivery of Right
Certificates or of any Preferred Shares or Common Shares or other securities
upon the exercise or exchange of the Rights. The Company shall not, however, be
required to pay any transfer tax which may be payable in respect of any transfer
or delivery of Right Certificates to a Person other than, or in respect of the
issuance or delivery of certificates for the Preferred Shares or Common Shares
or other securities, as the case may be, in a name other than that of, the
registered holder of the Right Certificate evidencing Rights surrendered for
exercise or exchange or to issue or deliver any certificates for Preferred
Shares or Common Shares or other securities, as the case may be, upon the
exercise or exchange of any Rights until any such tax shall have been paid (any
such tax being payable by the holder of

                                       14
<PAGE>   18
                                                                     Exhibit 4.1

such Right Certificate at the time of surrender) or until it has been
established to the Company's satisfaction that no such tax is due.

         SECTION 10. Preferred Shares Record Date. Each Person in whose name any
certificate for Preferred Shares or Common Shares or other securities is issued
upon the exercise or exchange of Rights shall for all purposes be deemed to have
become the holder of record of the Preferred Shares or Common Shares or other
securities, as the case may be, represented thereby on, and such certificate
shall be dated, the date upon which the Right Certificate evidencing such Rights
was duly surrendered and payment of any Purchase Price (and any applicable
transfer taxes) was made; provided, however, that, if the date of such surrender
and payment is a date upon which the transfer books of the Company for the
Preferred Shares or Common Shares or other securities, as the case may be, are
closed, such Person shall be deemed to have become the record holder of such
Preferred Shares or Common Shares or other securities, as the case may be, on,
and such certificate shall be dated, the next succeeding Business Day on which
the transfer books of the Company for the Preferred Shares or Common Shares or
other securities, as the case may be, are open.

         SECTION 11.  Adjustments in Rights After there is an Acquiring Person;
Exchange of Rights for Shares; Business Combinations.

                  (a) Upon a Person becoming an Acquiring Person, proper
provision shall be made so that each holder of a Right, except as provided in
Section 7(e), shall thereafter have a right to receive, upon exercise thereof
for the Purchase Price in accordance with the terms of this Rights Agreement,
such number of one one-thousandths (1/1,000ths) of a Preferred Share as shall
equal the result obtained by multiplying the Purchase Price by a fraction, the
numerator of which is the number of one one-thousandths (1/1,000ths) of a
Preferred Share for which a Right is then exercisable and the denominator of
which is 50% of the market Value of the Common Shares on the date on which a
Person becomes an Acquiring Person. As soon as practicable after a Person
becomes an Acquiring Person (provided the Company shall not have elected to make
the exchange permitted by Section 11(b)(I) for all outstanding Rights), the
Company covenants and agrees to use its best efforts to:

                  (I) prepare and file a registration statement under the
Securities Act, on an appropriate form, with respect to the Preferred Shares
purchasable upon exercise of the Rights;

                  (II) cause such registration statement to become effective as
soon as practicable after such filing;

                  (III) cause such registration statement to remain effective
(with a prospectus at all times meeting the requirements of the Securities Act)
until the Expiration Date; and

                  (IV) qualify or register the Preferred Shares purchasable upon
exercise of the Rights under the blue sky or securities laws of such
jurisdictions as may be necessary or appropriate.

                  (b) (I) The Board of Directors of the Company may, at its
option, at any time after a Person becomes an Acquiring Person, mandatorily
exchange all or part of the then outstanding and exercisable Rights (which shall
not include Rights that shall have become null and void and nontransferable
pursuant to the provisions of Section 7(e)) for consideration per Right
consisting of one-half of the securities that would be issuable at such time
upon the exercise of one Right


                                       15
<PAGE>   19
                                                                     Exhibit 4.1

in accordance with Section 11(a) or, if applicable, Section 9(b) (the
consideration issuable per Right pursuant to this Section 11(b)(I) being the
"Exchange Consideration"). The Board of Directors of the Company may, at its
option, issue, in substitution for Preferred Shares, Common Shares in an amount
per Preferred Share equal to the Formula Number (as defined in the Certificate
of Designation) if there are sufficient Common Shares issued but not outstanding
or authorized but unissued. If the Board of Directors of the Company elects to
exchange all the Rights for Exchange Consideration pursuant to this Section
11(b)(I) prior to the physical distribution of the Rights Certificates, the
Corporation may distribute the Exchange Consideration in lieu of distributing
Right Certificates, in which case for purposes of this Rights Agreement holders
of Rights shall be deemed to have simultaneously received and surrendered for
exchange Right Certificates on the date of such distribution.

                           (II)  Any action of the Board of Directors of the
Company ordering the exchange of any Rights pursuant to Section 11(b)(I) shall
be irrevocable and, immediately upon the taking of such action and without any
further action and without any notice, the right to exercise any such Right
pursuant to Section 11(a) shall terminate and the only right thereafter of a
holder of such Right shall be to receive the Exchange Consideration in exchange
for each such Right held by such holder or, if the Exchange Consideration shall
not have been paid or issued, to exercise any such Right pursuant to Section 11
(c)(I). The Company shall promptly give public notice of any such exchange;
provided, however, that the failure to give, or any defect in, such notice shall
not affect the validity of such exchange. The Company promptly shall mail a
notice of any such exchange to all holders of such Rights at their last
addresses as they appear upon the registry books of the Rights Agent. Any notice
which is mailed in the manner herein provided shall be deemed given, whether or
not the holder receives the notice. Each such notice of exchange will state the
method by which the exchange of the Rights for the Exchange Consideration will
be effected and, in the event of any partial exchange, the number of Rights
which will be exchanged. Any partial exchange shall be effected pro rata based
on the number of Rights (other than Rights which shall have become null and void
and nontransferable pursuant to the provisions of Section 7(e)) held by each
holder of Rights.

                  (c) (I) In the event that, following a Distribution Date,
directly or indirectly, any transactions specified in the following clause (i),
(ii) or (iii) of this Section 11(c) (each such transaction being a "Business
Combination") shall be consummated:

                  (i)  the Company shall consolidate with, or merge with and
into, any Acquiring Person or any Affiliate or Associate of an Acquiring Person;

                  (ii) any Acquiring Person or any Affiliate or Associate of an
Acquiring Person shall merge with and into the Company and, in connection with
such merger, all or part of the Common Shares shall be changed into or exchanged
for capital stock or other securities of the Company or of any Acquiring Person
or Affiliate or Associate of an Acquiring Person or cash or any other property;
or
                  (iii) the Company shall sell, lease, exchange or otherwise
transfer or dispose of (or one or more of its Subsidiaries shall sell, lease,
exchange or otherwise transfer or dispose of), in one or more transactions, the
Major Part of the assets of the Company and its Subsidiaries (taken as a whole)
to any Acquiring Person or any Affiliate or Associate of an Acquiring Person,
then, in each case, proper provision shall be made so that each holder of a
Right, except as provided in Section 7(e), shall thereafter have the right to
receive, upon the


                                       16
<PAGE>   20
                                                                     Exhibit 4.1

exercise thereof for the Purchase Price in accordance with the terms of this
Rights Agreement, the securities specified below (or, at such holder's option,
the securities specified in Section 11(a)):

                  (A) If the Principal Party in such Business Combination has
Registered Common Shares outstanding, each Right shall thereafter represent the
right to receive, upon the exercise thereof for the Purchase Price in accordance
with the terms of this Rights Agreement, such number of Registered Common Shares
of such Principal Party, free and clear of all liens, encumbrances or other
adverse claims, as shall have an aggregate Market Value equal to the result
obtained by multiplying the Purchase Price by two;

                  (B) If the Principal Party involved in such Business
Combination does not have Registered Common Shares outstanding, each Right shall
thereafter represent the right to receive, upon the exercise thereof for the
Purchase Price in accordance with the terms of this Rights Agreement, at the
election of the holder of such Right at the time of the exercise thereof, any
of:

                  (1) such number of Common Shares of the Surviving Person in
such Business Combination as shall have an aggregate Book Value immediately
after giving effect to such Business Combination equal to the result obtained by
multiplying the Purchase Price by two;

                  (2) such number of Common Shares of the Principal Party in
such Business Combination (if the Principal Party is not also the Surviving
Person in such Business Combination) as shall have an aggregate Book Value
immediately after giving effect to such Business Combination equal to the result
obtained by multiplying the Purchase Price by two; or

                  (3) if the Principal Party in such Business Combination is an
Affiliate of one or more Persons which has Registered Common Shares outstanding,
such number of Registered Common Shares of whichever of such Affiliates of the
Principal Party has Registered Common Shares with the greatest aggregate Market
Value on the date of consummation of such Business Combination as shall have an
aggregate Market Value on the date of such Business Combination equal to the
result obtained by multiplying the Purchase Price by two.

                  (II) The Company shall not consummate any Business Combination
unless each issuer of Common Shares for which Rights may be exercised, as set
forth in this Section 11(c), shall have sufficient authorized Common Shares that
have not been issued or reserved for issuance (and which shall, when issued upon
exercise thereof in accordance with this Rights Agreement, be validly issued,
fully paid and nonassessable and free of preemptive rights, rights of first
refusal or any other restrictions or limitations on the transfer or ownership
thereof) to permit the exercise in full of the Rights in accordance with this
Section 11(c) and unless prior thereto:

                  (i) a registration statement under the Securities Act on an
appropriate form, with respect to the Rights and the Common Shares of such
issuer purchasable upon exercise of the Rights, shall be effective under the
Securities Act; and

                  (ii) the Company and each such issuer shall have:

                  (A) executed and delivered to the Rights Agent a supplemental
agreement providing for the assumption by such issuer of the obligations set
forth in this Section 11(c) (including the obligation of such issuer to issue


                                       17
<PAGE>   21
                                                                     Exhibit 4.1

Common Shares upon the exercise of Rights in accordance with the terms set forth
in Sections 11(c)(I) and 11(c)(III)) and further providing that such issuer, at
its own expense, will use its best efforts to:

                  (1) cause a registration statement under the Securities Act on
an appropriate form, with respect to the Rights and the Common Shares of such
issuer purchasable upon exercise of the Rights, to remain effective (with a
prospectus at all times meeting the requirements of the Securities Act) until
the Expiration Date;

                  (2) qualify or register the Rights and the Common Shares of
such issuer purchasable upon exercise of the Rights under the blue sky or
securities laws of such jurisdictions as may be necessary or appropriate; and

                  (3) list the Rights and the Common Shares of such issuer
purchasable upon exercise of the Rights on each national securities exchange on
which the Common Shares were listed prior to the consummation of the Business
Combination or, if the Common Shares were not listed on a national securities
exchange prior to the consummation of the Business Combination, on a national
securities exchange;

                  (B) furnished to the Rights Agent a written opinion of
independent counsel stating that such supplemental agreement is a valid, binding
and enforceable agreement of such issuer; and

                  (C) filed with the Rights Agent a certificate of a nationally
recognized firm of independent accountants setting forth the number of Common
Shares of such issuer which may be purchased upon the exercise of each Right
after the consummation of such Business Combination.

                  (III) After consummation of any Business Combination and
subject to the provisions of Section 11(c)(II), (i) each issuer of Common Shares
for which Rights may be exercised as set forth in this Section 11(c) shall be
liable for, and shall assume, by virtue of such Business Combination, all the
obligations and duties of the Company pursuant to this Rights Agreement, (ii)
The term "Company" shall thereafter be deemed to refer to such issuer, (iii)
each such issuer shall take such steps in connection with such consummation as
may be necessary to assure that the provisions hereof (including the provisions
of Sections 11(a) and 11(c)) shall thereafter be applicable, as nearly as
reasonably may be, in relation to its Common Shares thereafter deliverable upon
the exercise of the Rights, and (iv) the number of Common Shares of each such
issuer thereafter receivable upon exercise of any Right shall be subject to
adjustment from time to time in a manner and on terms as nearly equivalent as
practicable to the provisions of Sections 11 and 12 and the provisions of
Section 7, 9 and 10 with respect to the Preferred Shares shall apply, as nearly
as reasonably may be, on like terms to any such Common Shares.

         SECTION 12.  Certain Adjustments.

                  (a) To preserve the actual or potential economic value of the
Rights, if at any time after the date of this Rights Agreement there shall be
any change in the Common Shares or the Preferred Shares, whether by reason of
stock dividends, stock splits, recapitalization, mergers, consolidations,
combinations or exchanges of securities, split-ups, split-offs, spin-offs,
liquidations, other similar changes in capitalization, any distribution or
issuance of cash, assets, evidences of indebtedness or subscription rights,
options or warrants to holders of Common Shares or Preferred Shares, as the case
may be (other than distribution


                                       18
<PAGE>   22
                                                                     Exhibit 4.1

of the Rights or regular quarterly cash dividends) or otherwise, then, in each
such event the Board of Directors of the Company shall make such appropriate
adjustments in the number of Preferred Shares (or the number and kind of other
securities) issuable upon exercise of each Right, the Purchase Price and
Redemption Price in effect at such time and the number of Rights outstanding at
such time (including the number of Rights or fractional Rights associated with
each Common Share) such that following each adjustment such event shall not have
had the effect of reducing or limiting the benefits the holders of the Rights
would have had absent such event.

                  (b) If, as a result of an adjustment made pursuant to Section
12(a), the holder of any Right thereafter exercised shall become entitled to
receive any securities other than Preferred Shares, thereafter the number of
such securities so receivable upon exercise of any Right shall be subject to
adjustment from time to time in a manner and on terms as nearly equivalent as
practicable to the provisions of Sections 11 and 12 and the provisions of
Sections 7, 9 and 10 with respect to the Preferred Shares shall apply, as nearly
as reasonably may be, on like terms to any such other securities.

                  (c) All Rights originally issued by the Company subsequent to
any adjustment made to the amount of Preferred Shares or other securities
relating to a Right shall evidence the right to purchase, for the Purchase
Price, the adjusted number and kind of securities purchasable from time to time
hereunder upon exercise of the Rights, all subject to further adjustment as
provided herein.

                  (d) Irrespective of any adjustment or change in the Purchase
Price or the number of Preferred Shares or number of kind of other securities
issuable upon the exercise of the Rights, the Right Certificates theretofore and
thereafter issued may continue to express the terms which were expressed in the
initial Right Certificates issued hereunder.

                  (e) In any case in which action taken pursuant to Section
12(a) requires that an adjustment be made effective as of a record date for a
specified event, the Company may elect to defer until the occurrence of such
event the issuing to the holder of any Right exercised after such record date
the Preferred Shares and/or other securities, if any, issuable upon such
exercise over and above the Preferred Shares and/or other securities, if any,
issuable before giving effect to such adjustment; provided, however, that the
Company shall deliver to such holder a due bill or other appropriate instrument
evidencing such holder's right to receive such additional securities upon the
occurrence of the event requiring such adjustment.

         SECTION 13. Certificate of Adjustment. Whenever an adjustment is made
as provided in Section 11 or 12, the Company shall (a) promptly prepare a
certificate setting forth such adjustment and a brief statement of the facts
accounting for such adjustment (b) promptly file with the Rights Agent and with
each transfer agent for the Preferred Shares a copy of such certificate and (c)
mail a brief summary thereof to each holder of a Right Certificate (or, prior to
the Distribution Date, of the Common Shares) in accordance with Section 25. The
Rights Agent shall be fully protected in relying on any such certificate and on
any adjustment therein contained.

         SECTION 14.  Additional Covenants.

                  (a) Notwithstanding any other provision of this Rights
Agreement, no adjustment to the number of Preferred Shares (or fractions of a
share) or other


                                       19
<PAGE>   23
                                                                     Exhibit 4.1

securities or which a Right is exercisable or the number of Rights outstanding
or associated with each Common Share or any similar or other adjustment shall be
made or be effective if such adjustment would have the effect of reducing or
limiting the benefits the holders of the Rights would have had absent such
adjustment, including, without limitation, the benefits under Sections 11 and
12, unless the terms of this Rights Agreement are amended so as to preserve such
benefits.

                  (b) The Company covenants and agrees that, after the
Distribution Date, except as permitted by Section 26, it will not take (or
permit any Subsidiary of the Company to take) any action if at the time such
action is taken it is intended or reasonably foreseeable that such action will
reduce or otherwise limit the benefits the holders of the Rights would have had
absent such action, including, without limitations, the benefits under Sections
11 and 12. Any action taken by the Company during any period after any Person
becomes an Acquiring Person but prior to the Distribution Date shall be null and
void unless such action could be taken under this Section 14(b) from and after
the Distribution Date. The Company shall not consummate any Business Combination
if any issuer of Common Shares for which Rights may be exercised after such
Business Combination in accordance with Section 11(c) shall have taken any
action that reduces or otherwise limits the benefits the holders of the Rights
would have had absent such action, including, without limitation, the benefits
under Sections 11 and 12.

         SECTION 15.  Fractional Rights and Fractional Shares.

                  (a) The Company may, but shall not be required to, issue
fractions of Rights or distribute Right Certificates which evidence fractional
Rights. In lieu of such fractional Rights, the Company may pay to the registered
holders of the Right Certificates with regard to which such fractional Rights
would otherwise be issuable an amount in cash equal to the same fraction of the
current market value of a whole Right. For purposes of this Section 15(a), the
current market value of a whole Right shall be the closing price of the Rights
(as determined pursuant to the second and third sentences of the definition of
Market Value contained in Section 1) for the Trading Day immediately prior to
the date on which such fractional Rights would have been otherwise issuable.

                  (b) The Company may, but shall not be required to, issue
fractions of Preferred Shares upon exercise of the Rights or distribute
certificates which evidence fractional Preferred Shares. In lieu of fractional
Preferred Shares, the Company may elect to (i) utilize a depository arrangement
as provided by the terms of the Preferred Shares or (ii) in the case of a
fraction of a Preferred Share (other than one one-thousandths (1/1,000ths) of a
Preferred Share or any integral multiple thereof), pay to the registered holders
of Right Certificates at the time such Rights are exercised as herein provided
an amount in cash equal to the same fraction of the current market value of one
Preferred Share, if any are outstanding and publicly traded (or the Formula
Number times the current market value of one Common Share if the Preferred
Shares are not outstanding and publicly traded). For purposes of this Section
15(b), the current market value of a Preferred Share (or Common Share) shall be
the closing price of a Preferred Share (or Common Share) (as determined pursuant
to the second and third sentences of the definition of Market Value contained in
Section 1) for the Trading Day immediately prior to the date of such exercise.
If, as a result of an adjustment made pursuant to Section 12(a), the holder of
any Right thereafter exercised shall become entitled to receive any securities
other than Preferred Shares, the provisions of this Section 15(b) shall apply,
as nearly as reasonably may be, on like terms to such other securities.


                                       20
<PAGE>   24
                                                                     Exhibit 4.1

                  (c) The Company may, but shall not be required to, issue
fractions of Common Shares upon exchange of Rights pursuant to Section 11(b), or
to distribute certificates which evidence fractional Common Shares. In lieu of
such fractional Common Shares, the Company may pay to the registered holders of
the Right Certificates with regard to which such fractional Common Shares would
otherwise be issuable an amount in cash equal to the same fraction of the
current Market Value of one Common Share as of the date on which a Person became
an Acquiring Person.

                  (d) The holder of Rights by the acceptance of the Rights
expressly waives his right to receive any fractional Rights or any fractional
shares upon exercise of a Right except as provided in this Section 15.

         SECTION 16.  Rights of Action.

                  (a) All rights of action in respect of this Rights Agreement
are vested in the respective registered holders of the Right Certificates (and,
prior to the Distribution Date, the registered holders of the Common Shares);
and any registered holder of any Right Certificate (or, prior to the
Distribution Date, of the Common Shares), without the consent of the Rights
Agent or of the holder of any other Right Certificate (or, prior to the
Distribution Date, of the Common Shares) may, in his own behalf and for his own
benefit, enforce, and may institute and maintain any suit, action or proceeding
against the Company to enforce, or otherwise act in respect of, his right to
exercise the Rights evidenced by such Right Certificate in the manner provided
in such Right Certificate and in this Rights Agreement. Without limiting the
foregoing or any remedies available to the holders or Rights, it is specifically
acknowledged that the holders of Rights would not have an adequate remedy at law
for any breach of this Rights Agreement and shall be entitled to specific
performance of the obligations of any Person under, and injunctive relief
against actual or threatened violations of the obligations of any Person subject
to, this Rights Agreement.

                  (b) Any holder of Rights who prevails in an action to enforce
the provisions of this Rights Agreement shall be entitled to recover the
reasonable costs and expenses, including attorneys' fees, incurred in such
action.

         SECTION 17.  Transfer and Ownership of Rights and Right Certificates.

                  (a) Prior to the Distribution Date, the Rights will be
transferable only in connection with the transfer of the Common Shares.

                  (b) After the Distribution Date, the Right Certificates will
be transferable, subject to Section 7(e), only on the registry books of the
Rights Agent, if surrendered at the principal office of the Rights Agent, duly
endorsed or accompanied by a proper instrument of transfer.

                  (c) The Company and the Rights Agent may deem and treat the
Person in whose name a Right Certificate (or, prior to the Distribution Date,
the associated Common Shares certificate) is registered as the absolute owner
thereof and of the Rights evidenced thereby (notwithstanding any notations of
ownership or writing on the Right Certificates or the associated certificate for
Common Shares made by anyone other than the Company or the Rights Agent) for all
purposes whatsoever, and neither the Company nor the Rights Agent shall be
affected by any notice to the contrary.

                                       21
<PAGE>   25
                                                                     Exhibit 4.1

         SECTION 18.  Right Certificate Holder Not Deemed a Stockholder.

         No holder, as such, of any Right Certificate shall be entitled to vote
or receive dividends or be deemed, for any purpose, the holder of the Preferred
Shares or of any other securities of the Company which may at any time be
issuable on the exercise of the Rights represented thereby, nor shall anything
contained herein or in any Right Certificate be construed to confer upon the
holder of any Right Certificate, as such, any of the rights of a stockholder of
the Company, including, without limitation, any right to vote for the election
of directors or upon any matter submitted to stockholders at any meeting
thereof, or to give or withhold consent to any corporate action, or to receive
notice of meetings or other actions affecting stockholders, or to receive
dividends or other distributions or subscription rights, or otherwise, until the
Right or Rights evidenced by such Right Certificate shall have been exercised in
accordance with the provisions hereof.

         SECTION 19.  Concerning the Rights Agent.

                  (a) The Company agrees to pay to the Rights Agent reasonable
compensation for all services rendered by it hereunder and from time to time, on
demand of the Rights Agent, its reasonable expenses and counsel fees and other
disbursements incurred in the administration and execution of this Rights
Agreement and the exercise and performance of its duties hereunder.

                  (b) The Rights Agent shall be protected and shall incur no
liability for or in respect of any action taken, suffered or omitted by it in
connection with its administration of this Rights Agreement in reliance upon any
Right Certificate or certificate for the Common Shares or for other securities
of the Company, instrument of assignment or transfer, power of attorney,
endorsement, affidavit, letter, notice, direction, consent, certificate,
statement, or other paper or document believed by it to be genuine and to be
signed, executed and, where necessary, verified or acknowledged, by the proper
Person or Persons.

         SECTION 20.  Merger or Consolidation or Change of Rights Agent.

                  (a) Any corporation into which the Rights Agent or any
successor Rights Agent may be merged or with which it may be consolidated, or
any corporation resulting from any merger or consolidation to which the Rights
Agent or any successor Rights Agent shall be a party, or any corporation
succeeding to the stock transfer or corporate trust business of the Rights Agent
or any successor Rights Agent, shall be the successor to the Rights Agent under
this Rights Agreement without the execution or filing of any paper or any
further act on the part of any of the parties hereto; provided that such
corporation would be eligible for appointment as a successor Rights Agent under
the provisions of Section 22. In case, at the time such successor Rights Agent
may adopt the countersignature of the predecessor Rights Agent shall succeed to
the agency created by this Rights Agreement, of any of the Right Certificates
shall have been countersigned but not delivered, any such successor Rights Agent
may adopt the countersignature of the predecessor Rights Agent and deliver such
Right Certificates so countersigned; and, in case at that time any of the Right
Certificates shall not have been countersigned, any successor Rights Agent
countersign such Right Certificate either in the name of the predecessor Rights
Agent or in the name of the successor Rights Agent; and in all such cases such
Right Certificates shall have the full force provided in the Right Certificates
and in this Rights Agreement.

                                       22
<PAGE>   26
                                                                     Exhibit 4.1

                  (b) In case at any time the name of the Rights Agent shall be
changed and at such time any of the Right Certificates shall have been
countersigned but not delivered, the Rights Agent may adopt the countersignature
under its prior name and deliver Right Certificates so countersigned; and, in
case at that time any of the Right Certificates shall have been countersigned
but not delivered, the Rights Agent may adopt the countersignature under its
prior name and deliver Right Certificates so countersigned; and, in case at that
time any of the Rights Certificates shall not have been countersigned, the
Rights Agent may countersign such Right Certificate either in its prior name or
in its changed name; and in all such cases such Right Certificates shall have
the full force provided in the Right Certificates and in this Rights Agreement.

         SECTION 21. Duties of Rights Agent. The Rights Agent undertakes the
duties and obligations imposed by this Rights Agreement upon the following terms
and conditions, by all of which the Company and the holders of Rights
Certificates (or, prior to the Distribution Date, of the Common Shares), by
their acceptance thereof, shall be bound:

                  (a) The Rights Agent may consult with legal counsel (who may
be legal counsel for the Company), and the opinion of such counsel shall be full
and complete authorization and protection to the Rights Agent as to any action
taken, suffered or omitted by it in good faith and in accordance with such
opinion.

                  (b) Whenever in the performance of its duties under this
Rights Agreement the Rights Agent shall deem it necessary or desirable that any
fact or matter (including, without limitation, the identity of any Acquiring
Person) be proved or established by the Company prior to taking, refraining from
taking or suffering any action hereunder, such fact or matter (unless other
evidence in respect thereof be herein specifically prescribed) may be deemed to
be conclusively proved and established by a certificate signed by any one of the
Chairman of the Board, the Chief Executive Officer, the President, the Chief
Operating Officer, the Chief Financial Officer, a Vice President (whether
preceded by any additional title), the Treasurer or the Secretary of the Company
and delivered to the Rights Agent; and such certificate shall be full
authorization to the Rights Agent for any action taken or suffered in good faith
by it under the provisions of this Rights Agreement in reliance upon such
certificate.

                  (c) The Rights Agent shall be liable hereunder only for its
own negligence, bad faith or wilful misconduct.

                  (d) The Rights Agent shall not be liable for or by reason of
any of statements of fact or recitals contained in this Rights Agreement or in
the Right Certificates (except as to its countersignature thereof) or be
required to verify the same, but all such statements and recitals are and shall
be deemed to have been made by the Company only.

                  (e) The Rights Agent shall not be under any responsibility in
respect of the validity of this Rights Agreement or the execution and delivery
hereof (except the due execution hereof by the Rights Agent) or in respect of
the validity or execution of any Right Certificate (except its countersignature
thereof); nor shall it be responsible for any breach by the Company of any
covenant or condition contained in this Rights Agreement or in any Right
Certificate; nor shall it be responsible for any adjustment required under the
provisions of Section 11 or 12 or responsible for the manner, method or amount
of any such adjustment or the ascertaining of the existence of facts that would
require any such adjustment (except with respect to the exercise of Rights

                                       23
<PAGE>   27
                                                                     Exhibit 4.1

evidenced by Right Certificates after actual notice of any such adjustment); nor
shall it by any act hereunder be deemed to make any representation or warranty
as to the authorization or reservation of any Preferred Shares or Common Shares
to be issued pursuant to this Rights Agreement or any Right Certificate or as to
whether any Preferred Shares or Common Shares will, when so issued, be validly
authorized and issued, fully paid and nonassessable.

                  (f) The Company agrees that it will perform, execute,
acknowledge and deliver or cause to be performed, executed, acknowledged and
delivered all such further and other acts, instruments and assurances as may
reasonably be required by the Rights Agent for the carrying out or performing by
the Rights Agent of the provisions of this Rights Agreement.

                  (g) The Rights Agent is hereby authorized and directed to
accept instructions with respect to the performance of its duties hereunder from
any one of the Chairman of the Board, the Chief Executive Officer, the
President, the Chief Operating Officer, a Vice President (whether preceded by
any additional title), the Secretary or the Treasurer of the Company, in
connection with its duties and it shall not be liable for any action taken or
suffered to be taken by it in good faith in accordance with instructions of any
such officer.

                  (h) The Rights Agent and any stockholder, director, officer or
employee of the Rights Agent may buy, sell or deal in any of the Rights or other
securities of the Company or become pecuniarily interested, or contract with or
lend money to the Company or otherwise act as fully and freely as though it were
not the Rights Agent under this Rights Agreement. Nothing herein shall preclude
the Rights Agent from acting in any other capacity for the Company or for any
other legal entity.

                  (i) The Rights Agent may execute an exercise any of the rights
or powers hereby vested in it or perform any duty hereunder either itself or by
or through its attorneys or agents, and the Rights Agent shall not be answerable
or accountable for any act, default, neglect or misconduct of any such attorneys
or agents of for any loss to the Company resulting from any such act, default,
neglect or misconduct provided reasonable care was exercised in the selection
and continued employment thereof.

                  (j) The Company agrees to indemnify and to hold the Rights
Agent harmless against any loss, liability, damage or expense (including
reasonable fees and expenses of (legal counsel) which the Rights Agent may incur
resulting from its actions as Rights Agent pursuant to this Rights Agreement;
provided, however, that the Rights Agent shall not be indemnified or held
harmless with respect to any such loss, liability, damage or expense incurred by
the Rights Agent as a result of, or arising out of, its own negligence, bad
faith or wilful misconduct. In no case shall the Company be liable with respect
to any action, proceeding, suit or claim against the Rights Agent unless the
Rights Agent shall have notified the Company, by letter or by facsimile
confirmed by letter, of the assertion of any action, proceeding, suit or claim
against the Rights Agent, promptly after the Rights Agent shall have notice of
any such assertion of an action, proceeding, suit or claim or have been served
with the summons or other first legal process giving information as to the
nature and basis of the action, proceeding, suit or claim. The Company shall be
entitled to participate at its own expense in the defense of any such action,
proceeding, suit or claim, and, if the Company so elects, the Company shall
assume the defense of any such action, proceeding, suit or claim. In the event
that the Company assumes such defense, the Company shall not thereafter be
liable for the fees and expenses of any additional counsel retained by the
Rights Agent, so long as the Company shall


                                       24
<PAGE>   28
                                                                     Exhibit 4.1

retain counsel satisfactory to the Rights Agent, in the exercise of its
reasonable judgment, to defend such action, proceeding, suit or claim. The
Rights Agent agrees not to settle any litigation in connection with any action,
proceeding, suit or claim with respect to which it may seek indemnification from
the Company without the prior written consent of the Company.

         SECTION 22. Change of Rights Agent. The Rights Agent or any successor
Rights Agent may resign and be discharged from its duties under this Rights
Agreement upon 30 days' notice in writing mailed to the Company and to each
transfer agent of the Common Shares and the Preferred Shares by registered or
certified mail, and to the holders of the Right Certificates (or, prior to the
Distribution Date, of the Common Shares) by first-class mail. The Company may
remove the Rights Agent or any successor Rights Agent upon 30 days' notice in
writing, mailed to the Rights Agent or successor Rights Agent, as the case may
be, and to each transfer agent of the Common Shares and the Preferred Shares by
registered or certified mail, and to the holders of the Right Certificates (or,
prior to the Distribution Date, of the Common Shares) by first-class mail. If
the Rights Agent shall resign or be removed or shall otherwise become incapable
of acting, the Company shall appoint a successor to the Rights Agent. If the
Company shall fail to make such appointment within a period of 30 days after
giving notice of such removal or after it has been notified in writing of such
resignation or incapacity by the resigning or incapacitated Rights Agent or by
the holder of a Right Certificate (or, prior to the Distribution Date, of the
Common Shares) (who shall, with such notice, submit his Right Certificate or,
prior to the Distribution Date, the certificate representing his Common Shares,
for inspection by the Company), then the registered holder of any Right
Certificate (or, prior to the Distribution Date, of the Common Shares) may apply
to any court of competent jurisdiction for the appointment of a new Rights
agent. Any successor Rights Agent, whether appointed by the Company or by such
court, shall be a corporation organized and doing business under the laws of the
United States or of the State of New Jersey or New York (or of any other state
of the United States so long as such corporation is authorized to conduct a
stock transfer or corporate trust business in the State of New Jersey or New
York), in good standing, having a principal office in the State of New Jersey or
New York, which is authorized under such laws to exercise stock transfer or
corporate trust powers and is subject to supervision or examination by Federal
or state authority and which has at the time of its appointment as Rights Agent
a combined capital and surplus of at least $20,000,000; provided that the
principal transfer agent for the Common Shares shall in any event be qualified
to be the Rights Agent. After appointment, the successor Rights Agent shall be
vested with the same powers, rights, duties and responsibilities as if it had
been originally named as Rights Agent without further act or deed; but the
predecessor Rights Agent shall deliver and transfer to the successor Rights
Agent any property at the time held by it hereunder, and execute and deliver any
further assurance, conveyance, act or deed necessary for the purpose. Not later
than the effective date of any such appointment, the Company shall file notice
thereof in writing with the predecessor Rights Agent and each transfer agent of
the Common Shares and the Preferred Shares, and mail a notice thereof in writing
to the registered holders of the Right Certificates (or, prior to the
Distribution Date, of the Common Shares). Failure to give any notice provided
for in this Section 22, however, or any defect therein shall not affect the
legality or validity of the resignation or removal of the Rights Agent or the
appointment of the successor Rights Agent, as the case may be.

         SECTION 23. Issuance of Additional Rights and Right Certificates.
Notwithstanding any of the provisions of this Rights Agreement or of the Rights
to the contrary, the Company may, at its option, issue new Right


                                       25
<PAGE>   29
                                                                     Exhibit 4.1

Certificates evidencing Rights in such form as may be approved by its Board of
Directors to reflect any adjustment or change made in accordance with the
provisions of this Rights Agreement. In addition, in connection with the
issuance or sale of Common Shares following the Distribution Date and prior to
the earlier of the Redemption Date and the Expiration Date, the Company (a)
shall, with respect to Common Shares so issued or sold pursuant to the exercise
of stock options or under any employee plan or arrangement, or upon the
exercise, conversion or exchange of securities, notes or debentures issued by
the Company, and (b) may, in any other case, if deemed necessary or appropriate
by the Board of Directors number of Rights in connection with such issuance or
sale; provided, however, that (i) no such Right Certificate shall be issued if,
and to the extent that, the Company shall be advised by counsel that such
issuance would create a significant risk of material adverse tax consequences to
the Company or the Person to whom such Right Certificate wold be issued, and
(ii) no such Right Certificate shall be issued if, and to the extent that,
appropriate adjustment shall otherwise have been made in lieu of the issuance
thereof.

         SECTION 24.  Redemption and Termination.

                  (a) The Board of Directors of the Company may, at its option,
at any time prior to the earlier of (i) such time as a Person becomes an
Acquiring Person and (ii) the Expiration Date, order the redemption of all, but
not fewer than all, the then outstanding Rights at the Redemption Price (the
date of such redemption being the "Redemption Date"), and the Company, at its
option, may pay the Redemption Price either in cash or Common Shares or other
securities of the Company deemed by the Board of Directors of the Company, in
the exercise of its sole discretion, to be at least equivalent in value to the
Redemption Price; provided, however, that, in addition to any other limitations
contained herein on the right to redeem outstanding Rights (including the
occurrence of any event or the expiration of any period after which the Rights
may no longer be redeemed), for the 120-day period after any date of a change
(resulting from a proxy or consent solicitation) in a majority of the Board of
Directors of the Company in office at the commencement of such solicitation, the
Rights may only be redeemed if (A) there are directors then in office who were
in office at the commencement of such solicitation and (B) the Board of
Directors of the Company, with the concurrence of a majority of such directors
then in office, determines that such redemption is, in their judgment, in the
best interests of the Company and its stockholders.

                  (b) Immediately upon the action of the Board of Directors of
the Company ordering the redemption of the Rights, and without any further
action and without any notice, the right to exercise the Rights will terminate
and the only right thereafter of the holders of Rights shall be to receive the
Redemption Price. Within 10 Business Days after the action of the Board of
Directors of the Company ordering the redemption of the Rights, the Company
shall give notice of such redemption to the holders of the then outstanding
Rights by mailing such notice to all such holders at their last addresses as
they appear upon the registry books of the Rights Agent or, prior to the
Distribution Date, on the registry books of the transfer agent for the Common
Shares. Each such notice of redemption will state the method by which payment of
the Redemption Price will be made. The notice, if mailed in the manner herein
provided, shall be conclusively presumed to have been duly given, whether or not
the holder of Rights receives such notice. In any case, failure to give such
notice by mail, or any defect in the notice, to any particular holder of Rights
shall not affect the sufficiency of the notice to other holders of Rights.


                                       26
<PAGE>   30
                                                                     Exhibit 4.1

         SECTION 25. Notices. Notices or demands authorized by this Agreement to
be given or made by the Rights Agent or by the holder of a Right Certificate
(or, prior to the Distribution Date, of the Common Shares) to or on the Company
shall be sufficiently given or made if sent by first-class mail, postage
prepaid, addressed (until another address is filed in writing with the Rights
Agent) as follows:

                  Alteon, Inc.
                  170 Williams Drive
                  Ramsey, New Jersey  07446
                  Attn: Chief Executive Officer

Subject to the provisions of Section 22, any notice or demand authorized by this
Rights Agreement to be given or made by the Company or by the holder of a Right
Certificate (or, prior to the Distribution Date, of the Common Shares) to or on
the Rights Agent shall be sufficiently given or made if sent by first-class
mail, postage prepaid, addressed (until another address is filed in writing with
the Company) as follows:

                  Registrar and Transfer Company
                  10 Commerce Drive
                  Cranford, New Jersey 07061
                  Attn:  Corporate Relations Department

         Notices or demands authorized by this Rights Agreement to be given or
made by the Company or the Rights Agent to any holder of a Right Certificate
(or, prior to the Distribution Date, of the Common Shares) shall be sufficiently
given or made if sent by first-class mail, postage prepaid, addressed to such
holder at the address of such holder as shown on the registry books of the
Rights Agent or, prior to the Distribution Date, on the registry books of the
transfer agent for the Common Shares.

         SECTION 26. Supplements and Amendments. At any time prior to the
Distribution Date and subject to the last sentence of this Section 26, the
Company may, and the Rights Agent shall if the Company so directs, supplement or
amend any provision of this Rights Agreement (including, without limitation, the
date on which the Distribution Date shall occur, the time during which the
Rights may be redeemed pursuant to Section 24 or any provision of the
Certificate of Designation) without the approval of any holder of the Rights.
From and after the Distribution Date and subject to applicable law, the Company
may, and the Rights Agent shall if the Company so directs, amend this Rights
Agreement without the approval of any holders of Right Certificates (i) to cure
an ambiguity or to correct or supplement any provision contained herein which
may be defective or inconsistent with any other provision of this Rights
Agreement or (ii) to make any other provisions in regard to matters or questions
arising hereunder which the Company may deem necessary or desirable and which
shall not adversely affect the interests of the holders of Right Certificates
(other than an Acquiring Person or an Affiliate or Associate of an Acquiring
Person). Any supplement or amendment adopted during any period after any Person
has become an Acquiring Person but prior to the Distribution Date shall be null
and void unless such supplement or amendment could have been adopted under the
prior sentence from and after the Distribution Date. Any supplement or amendment
to this Rights Agreement duly approved by the Company that does not amend
Sections 19, 20, 21 or 22 in a manner adverse to the Rights Agent shall become
effective immediately upon execution by the Company, whether or not also
executed by the Rights Agent. Notwithstanding anything contained in this Rights
Agreement to the contrary, during the 120-day period after any date of a change
(resulting from a proxy or


                                       27
<PAGE>   31
                                                                     Exhibit 4.1

consent solicitation) in a majority of the Board of Directors of the Company in
office at the commencement of such solicitation, this Rights Agreement may be
supplemented or amended only if (A) there are directors then in office who were
in office at the commencement of such solicitation and (B) the Board of
Directors of the Company, with the concurrence of a majority of such directors
then in office, determines that such supplement or amendment is, in their
judgment, in the best interests of the Company and its stockholders and, after
the Distribution Date, the holders of the Right Certificates. In addition,
notwithstanding anything to the contrary contained in this Rights Agreement, no
supplement or amendment to this Rights Agreement shall be made which (a) reduces
the Redemption Price (except as required by Section 12(a)) or (b) provides for
an earlier Expiration Date.

         SECTION 27. Successors. All the covenants and provisions of this Rights
Agreement by or for the benefit of the Company or the Rights Agent shall bind
and inure to the benefit of their respective successors and assigns hereunder.

         SECTION 28.  Benefits of Rights Agreement; Determinations and Actions
by the Board of Directors, etc.

                  (a) Nothing in this Rights Agreement shall be construed to
give to any Person other than the Company, the Rights Agent and the registered
holders of the Right Certificates (and, prior to the Distribution Date, of the
Common Shares) any legal or equitable right, remedy or claim under this Rights
Agreement; but this Rights Agreement shall be for the sole and exclusive benefit
of the Company, the Rights Agent and the registered holders of the Right
Certificates (and, prior to the Distribution Date, of the Common Shares).

                  (b) Except as explicitly otherwise provided in this Rights
Agreement, the Board of Directors of the Company shall have the exclusive power
and authority to administer this Rights Agreement and to exercise all rights and
powers specifically granted to the Board of Directors of the Company or to the
Company, or as may be necessary or advisable in the administration of this
Rights Agreement, including, without limitation, the right and power to (i)
interpret the provisions of this Rights Agreement and (ii) make all
determinations deemed necessary or advisable for the administration of this
Rights Agreement (including, without limitation, a determination to redeem or
not redeem the Rights or to amend this Rights Agreement and a determination of
whether an offer constitutes a Qualifying Offer and whether there is an
Acquiring Person).

                  (c) Nothing contained in this Rights Agreement shall be deemed
to be in derogation of the obligation of the Board of Directors of the Company
to exercise its fiduciary duty. Without limiting the foregoing, nothing
contained herein shall be construed to suggest or imply that the Board of
Directors shall not be entitled to reject any Qualifying Offer or any other
tender offer, or to recommend that holders of Common Shares reject any
Qualifying Offer or any other tender offer, or to take any other action
(including, without limitation, the commencement, prosecution, defense or
settlement of any litigation and the submission of additional or alternative
offers or other proposals) with respect to any Qualifying Offer or any other
tender offer that the Board of Directors believes is necessary or appropriate in
the exercise of such fiduciary duty.

         SECTION 29. Severability. If any term, provision, covenant or
restriction of this Rights Agreement is held by a court of competent
jurisdiction or other authority to be invalid, void or unenforceable, the
remainder of the terms, provisions, covenants and restrictions of this Rights
Agreement shall remain in full force and effect and shall in no way be affected,
impaired or invalidated.

                                       28
<PAGE>   32
                                                                     Exhibit 4.1

         SECTION 30. Governing Law. This Rights Agreement and each Right
Certificate issued hereunder shall be deemed to be a contract made under the law
of the State of Delaware and for all purposes shall be governed by and construed
in accordance with the law of such State applicable to contracts to be made and
performed entirely within such State.

         SECTION 31. Counterparts; Effectiveness. This Rights Agreement may be
executed in any number of counterparts and each of such counterparts shall for
all purposes be deemed to be an original, and all such counterparts shall
together constitute but one and the same instrument. This Rights Agreement shall
be effective as of the Close of Business on the date hereof.

         SECTION 32. Descriptive Headings. Descriptive headings of the several
Sections of this Rights Agreement are inserted for convenience only and shall
not control or affect the meaning or construction of any of the provisions of
this Rights Agreement.





                  IN WITNESS WHEREOF, the parties hereto have caused this Rights
Agreement to be duly executed as of the day and year first above written.

                                       ALTEON INC.



                                       by: /s/ James J. Mauzey
                                           ---------------------------------
                                                Name: James J. Mauzey
                                                Title: Chairman & Chief
                                                       Executive Officer


                                       REGISTRAR AND TRANSFER COMPANY, as Rights
                                       Agent



                                       by: /s/ William P. Tatler
                                           ---------------------------------
                                            Name: William P. Tatler
                                            Title: Vice President



                                       29
<PAGE>   33
                                                                     Exhibit 4.1

Exhibits to Rights Agreement.



                                       30
<PAGE>   34
                                                                     Exhibit 4.1
                                                                       EXHIBIT A


                        CERTIFICATE OF THE VOTING POWERS,
                     DESIGNATIONS, PREFERENCES AND RELATIVE
                    PARTICIPATING, OPTIONAL AND OTHER SPECIAL
                     RIGHTS AND QUALIFICATIONS, LIMITATIONS
                           OR RESTRICTIONS OR SERIES F
                               PREFERRED STOCK OF
                                   ALTEON INC.


                  Pursuant to Section 151 of the General Corporation Law of the
State of Delaware, Alteon Inc. (the "Corporation") organized and existing under
the General Corporation Law of the State of Delaware, in accordance with the
provisions of Section 103 thereof, DOES HEREBY CERTIFY:

                  That, pursuant to the authority conferred upon the Board of
Directors of the Corporation by Article Fifth of the Restated Certificate of
Incorporation of the Corporation (the "Certificate of Incorporation"), the Board
of Directors of the Corporation on __________, 1995, adopted the following
resolution creating a series of Preferred Stock designated as Series F Preferred
Stock:

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

         SECTION 1. Designation and Number of Shares. The shares of such series
shall be designated as "Series F Preferred Stock" (the "Series F Preferred
Stock"), par value $0.01 per share. The number of shares initially constituting
the Series F Preferred Stock shall be 400,000; provided, however, that, if more
than a total of 400,000 shares of Series F Preferred Stock shall be issuable
upon the exercise of Rights (the "Rights") issued pursuant to the Stockholders
Rights Agreement dated as of ________________, 1995, between the Corporation and
Registrar and Transfer Company, as Rights Agent (the "Rights Agreement"), the
Board of Directors of the Corporation, pursuant to Section 151(g) of the General
Corporation Law of the State of Delaware, shall direct by resolution or
resolutions that a certificate be properly executed, acknowledged, filed and
recorded, in accordance with the provisions of Section 103 thereof, providing
for the total number of shares of Series F Preferred Stock authorized to be
issued to be increased (to the extent that the Certificate of Incorporation then
permits) to the largest number of whole shares (rounded up to the nearest whole
number) issuable upon exercise of such Rights.

         SECTION 2. Dividends or Distributions. (a) Subject to the prior and
superior rights of the holders of shares of any other series of Preferred Stock
or other class of capital stock of the Corporation ranking prior and superior to
the shares of Series F Preferred Stock with respect to dividends, the holders of
shares of the Series F Preferred Stock shall be entitled to receive, when, as
and if declared by the Board of Directors, out of the assets of the Corporation
legally available therefore, (1) quarterly dividends payable in cash on the last
day of each fiscal quarter in each year, or such other dates as the Board of

                                       31
<PAGE>   35
                                                                     Exhibit 4.1

Directors of the Corporation shall approve (each such date being referred to
herein as a "Quarterly Dividend Payment Date"), commencing on the first
Quarterly Dividend Payment Date after the first issuance of a share or a
fraction of a share of Series F Preferred Stock, in the amount of $.01 per whole
share (rounded to the nearest cent) less the amount of all cash dividends
declared on the Series F Preferred Stock pursuant to the following clause (2)
since the immediately preceding Quarterly Dividend Payment Date or, with respect
to the first Quarterly Dividend Payment Date, since the first issuance of any
share or fraction of a share of Series F Preferred Stock (the total of which
shall not, in any event, be less than zero) and (2) dividends payable in cash on
the payment date for each cash dividend declared on the Common Stock in an
amount per whole share (rounded to the nearest cent) equal to the Formula Number
(as hereinafter defined) then in effect times the cash dividends then to be paid
on each share of Common Stock. In addition, if the Corporation shall pay any
dividend or make any distribution on the Common Stock payable in assets,
securities or other forms of noncash consideration (other than dividends or
distributions solely in shares of Common Stock), then, in each such case, the
Corporation shall simultaneously pay or make on each outstanding whole share of
Series F Preferred Stock a dividend or distribution in like kind equal to the
Formula Number then in effect times such dividend or distribution on each share
of the Common Stock. As used herein, the "Formula Number" shall be 1,000;
provided, however, that, if at any time after July 20, 1995, the Corporation
shall (i) declare or pay any dividend on the Common Stock payable in shares of
Common Stock or make any distribution on the Common Stock in share of Common
Stock, (ii) subdivide (by a stock split or otherwise) the outstanding shares of
Common Stock into a larger number of shares of Common Stock or (iii) combine (by
a reverse stock split or otherwise) the outstanding shares of Common Stock, into
a smaller number of shares of Common Stock, then in each such event the Formula
Number shall be adjusted to a number determined by multiplying the Formula
Number in effect immediately prior to such event by a fraction, the numerator of
which is the number of shares of Common Stock that are outstanding immediately
after such event and the denominator of which is the number of shares of Common
Stock that are outstanding immediately prior to such event (and rounding the
result to the nearest whole number); and provided further, that, if an any time
after July 20, 1995, the Corporation shall issue any shares of its capital stock
in a merger, reclassification, or change of the outstanding shares of Common
Stock, then in each such event the Formula Number shall be appropriately
adjusted to reflect such merger, reclassification or change so that each share
of Preferred Stock continues to be the economic equivalent of a Formula Number
of shares of Common Stock prior to such merger, reclassification or change.

                  (b) The Corporation shall declare a dividend or distribution
on the Series F Preferred Stock as provided in Section 2(a) immediately prior to
or at the same time it declares a dividend or distribution on the Common Stock
(other than a dividend or distribution solely in shares of Common Stock);
provided, however, that, in the event no dividend or distribution (other than a
dividend or distribution in shares of Common Stock) shall have been declared on
the Common Stock during the period between any Quarterly Dividend Payment Date
and the next subsequent Quarterly Dividend Payment Date, a dividend of $.01 per
share on the Series F Preferred Stock shall nevertheless be payable on such
subsequent Quarterly Dividend Payment Date. The Board of Directors may fix a
record date for the determination of holders of shares of Series F Preferred
Stock entitled to receive a dividend or distribution declared thereon, which
record date shall be the same as the record date for corresponding dividend or
distribution on the Common Stock.


                                       32
<PAGE>   36
                                                                     Exhibit 4.1

                  (c) Dividends shall begin to accrue and be cumulative on
outstanding shares of Series F Preferred Stock from and after the Quarterly
Dividend Payment Date next preceding the date of original issue of such shares
of Series F Preferred Stock; provided, however, that dividends on such shares
which are originally issued after the record date for the determination of
holders of shares of Series F Preferred Stock entitled to receive a quarterly
dividend and on or prior to the next succeeding Quarterly Dividend Payment Date
shall begin to accrue and be cumulative from and after such Quarterly Dividend
Payment Date. Notwithstanding the foregoing, dividends on shares of Series F
Preferred Stock which are originally issued prior to the record date for the
determination of holders of shares of Series F Preferred Stock entitled to
receive a quarterly dividend on the first Quarterly Dividend Payment Date shall
be calculated as if cumulative from and after the last day of the fiscal quarter
next preceding the date of original issuance of such shares. Accrued but unpaid
dividends shall not bear interest. Dividends paid on the shares of Series F
Preferred Stock in an amount less than the total amount of such dividends at the
time accrued and payable on such shares shall be allocated pro rata on a
share-by-share basis among all such shares at the time outstanding.

                  (d) So long as any shares of the Series F Preferred Stock are
outstanding, no dividends or other distributions shall be declared, paid or
distributed, or set aside for payment or distribution, on the Common Stock
unless, in each case, the dividend required by this Section 2 to be declared on
the Series F Preferred Stock shall have been declared.

                  (e) The holders of the shares of Series F Preferred Stock
shall not be entitled to receive any dividends or other distribution except as
provided herein.

         SECTION 3.  Voting Rights. The holders of shares of Series F Preferred
Stock shall have the following voting rights:

                  (a) Each holder of Series F Preferred Stock shall be entitled
to a number of votes equal to the Formula Number then in effect, for each share
of Series F Preferred Stock held of record on each matter on which holders of
the Common Stock or stockholders generally are entitled to vote, multiplied by
the maximum number of votes per share which any holder of the Common Stock or
stockholders generally then have with respect to such matter (assuming any
holding period or other requirement to vote a greater number of shares is
satisfied).

                  (b) Except as otherwise provided herein or by applicable law,
the holders of shares of Series F Preferred Stock and the holders of shares of
Common Stock shall vote together as one class for the election of directors of
the Corporation and on all other matters submitted to a vote of stockholders of
the Corporation.

                  (c) If, at the time of any annual meeting of stockholders for
the election of directors, the equivalent of six quarterly dividends (whether or
not consecutive) payable on any share or shares of Series F Preferred Stock are
in default, the number of directors constituting the Board of Directors of the
Corporation shall be increased by two. In addition to voting together with the
holders of Common Stock for the election of other directors of the Corporation,
the holders of record of the Series F Preferred Stock, voting separately as a
class to the exclusion of the holders of Common Stock, shall be entitled at said
meeting of stockholders (and at each subsequent annual meeting of stockholders),
unless all dividends in arrears have been paid or declared and set apart for

                                       33
<PAGE>   37
                                                                     Exhibit 4.1

payment prior thereto, to vote for the election of two directors of the
Corporation, the holders of any Series F Preferred Stock being entitled to cast
a number of votes per share of Series F Preferred Stock equal to the Formula
Number. Until the default in payments of all dividends which permitted the
election of said directors shall cease to exist, any director who shall have
been so elected pursuant to the next preceding sentence may be removed at any
time, either with or without cause, only by the affirmative vote of the holders
of the shares of Series F Preferred Stock at the time entitled to cast a
majority of the votes entitled to be cast for the election of any such director
at a special meeting of such holders called for that purpose, and any vacancy
thereby created may be filled by the vote of such holders. If and when such
default shall cease to exist, the holders of the Series F Preferred Stock shall
be divested of the foregoing special voting rights, subject to revesting in the
event of each and every subsequent like default in payments of dividends. Upon
the termination of the foregoing special voting rights, the terms of office of
all persons who may have been elected directors pursuant to said special voting
rights shall forthwith terminate, and the number of directors constituting the
Board of Director shall be reduced by two. The voting rights granted by this
Section 3(c) shall be in addition to any other voting rights granted to the
holders of the Series F Preferred Stock in this Section 3.

                  (d) Except as provided herein, in Section 11 or by applicable
law, holders of Series F Preferred Stock shall have no special voting rights and
their consent shall not be required (except to the extent they are entitled to
vote with holders of Common Stock as set forth herein) for authorizing or taking
any corporate action.

         SECTION 4.  Certain Restrictions.

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

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

         (ii) Declare or pay dividends on, or make any other distributions on
         any shares of stock ranking on a parity (either as to dividends or upon
         liquidation, dissolution or winding up) with the Series F Preferred
         Stock, except dividends paid ratably on the Series F Preferred Stock
         and all such parity stock on which dividends are payable or in arrears
         in proportion to the total amounts to which the holders of all such
         shares are then entitled;

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

                                       34
<PAGE>   38
                                                                     Exhibit 4.1

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

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

         SECTION 5. Liquidation Rights. Upon the liquidation, dissolution or
winding up of the Corporation, whether voluntary or involuntary, no distribution
shall be made (1) to the holders of shares of stock ranking junior (either as to
dividends or upon liquidation, dissolution or winding up) to the Series F
Preferred Stock unless, prior thereto, the holders of shares of Series F
Preferred Stock shall have received an amount equal to the accrued and unpaid
dividends and distributions thereon, whether or not declared, to the date of
such payment, plus an amount equal to the greater of (x) $.01 per whole share or
(y) an aggregate amount per share equal to the Formula Number then in effect
times the aggregate amount to be distributed per share to holders of Common
Stock or (2) to the holders of stock ranking on a parity (either as to dividends
or upon liquidation, dissolution or winding up) with the Series F Preferred
Stock, except distributions made ratably on the Series F Preferred Stock and all
other such parity stock in proportion to the total amounts to which the holders
of all such shares are entitled upon such liquidation, dissolution or winding
up.

         SECTION 6. Consolidation, Merger, etc. In case the Corporation shall
enter into any consolidation, merger, combination or other transaction in which
the shares of Common Stock are exchanged for or changed into other stock or
securities, cash or any other property, then in any such case the then
outstanding shares of Series F Preferred Stock shall at the same time be
similarly exchanged or changed into an amount per share equal to the Formula
Number then in effect times the aggregate amount of stock, securities, cash or
any other property (payable in kind), as the case may be, into which or for
which each share of Common Stock is exchanged or changed. In the event both this
Section 6 and Section 2 appear to apply to a transaction, this Section 6 will
control.

         SECTION 7.  No Redemption; No Sinking Fund.

                  (a) The shares of Series F Preferred Stock shall not be
subject to redemption by the Corporation or at the option of any holder of
Series F Preferred Stock except as set forth in the Certificate of Incorporation
of the Corporation; provided, however, that the Corporation may purchase or
otherwise acquire outstanding shares of Series F Preferred Stock in the open
market or by offer to any holder or holders of shares of Series F Preferred
Stock.

                  (b) The shares of Series F Preferred Stock shall not be
subject to or entitled to the operation of a retirement or sinking fund.

                                       35
<PAGE>   39
                                                                     Exhibit 4.1

         SECTION 8. Ranking. The Series F Preferred Stock shall rank junior to
all other series of Preferred Stock of the Corporation, unless the Board of
Directors shall specifically determine otherwise in fixing the powers,
preferences and relative, participating, optional and other special rights of
the shares of such series and the qualifications, limitations and restrictions
thereof.

         SECTION 9. Fractional Shares. The Series F Preferred Stock shall be
issuable upon exercise of the Rights issued pursuant to the Rights Agreement in
whole shares or in any fraction of a share that is one one-thousandths
(1/1,000ths) of a share of any integral multiple of such fraction which shall
entitle the holder, in proportion to such holder's fractional shares, to receive
dividends, exercise voting rights, participate in distributions and to have the
benefit of all other rights of holders of Series F Preferred Stock. In lieu of
fractional shares, the Corporation, prior to the first issuance of a share or a
fraction of a share of Series F Preferred Stock, may elect (1) to make a cash
payment as provided in the Rights Agreement for fractions of a share other than
one one-thousandths (1/1,000ths) of a share or any integral multiple thereof or
(2) to issue depository receipts evidencing such authorized fraction of a share
of Series F Preferred Stock pursuant to an appropriate agreement between the
Corporation and a depository selected by the Corporation; provided that such
agreement shall provide that the holders of such depository receipts shall have
all the rights, privileges and preferences to which they are entitled as holders
of the Series F Preferred Stock.

         SECTION 10. Reacquired Shares. Any shares of Series F Preferred Stock
purchased or otherwise acquired by the Corporation in any manner whatsoever
shall be retired and canceled promptly after the acquisition thereof. All such
shares shall upon their cancellation become authorized but unissued shares of
Preferred Stock, without designation as to series until such shares are once
more designated as part of a particular series by the Board of Directors
pursuant to the provisions of Article Fifth of the Certificate of Incorporation.

         SECTION 11. Amendment. None of the powers, preferences and relative,
participating, optional and other special rights of the Series F Preferred Stock
as provided herein or in the Certificate of Incorporation shall be amended in
any manner which would alter or change the powers, preferences, rights or
privileges of the holders of Series F Preferred Stock so as to affect them
adversely without the affirmative vote of the holders of at least 66-2/3% of the
outstanding shares of Series F Preferred Stock, voting as a separate class;
provided, however, that no such amendment approved by the holders of at least
66-2/3% of the outstanding shares of Series F Preferred Stock shall be deemed to
apply to the powers, preferences, rights or privileges of any holder of shares
of Series F Preferred Stock originally issued upon exercise of the Rights after
the time of such approval without the approval of such holder.

                  IN WITNESS WHEREOF, the Corporation has caused this
Certificate to be duly executed in its corporate name on this  day of
_____________ 1995.


                                       Alteon Inc.



                                        By:
                                           Name:
                                           Title:


                                       36
<PAGE>   40
                                                                     Exhibit 4.1

Attest:

Name:
Title:





                                       37
<PAGE>   41
                                                                     Exhibit 4.1
                                                                       EXHIBIT B

                           [Form of Right Certificate]


Certificate No. [R]-
                                  Rights
                  ---------------


                  NOT EXERCISABLE AFTER __________, 2005, OR EARLIER IF REDEEMED
                  BY THE COMPANY. THE RIGHTS ARE SUBJECT TO REDEMPTION, AT THE
                  OPTION OF THE COMPANY, AT $.01 PER RIGHT, ON THE TERMS SET
                  FORTH IN THE STOCKHOLDERS RIGHTS AGREEMENT. RIGHTS
                  BENEFICIALLY OWNED BY AN ACQUIRING PERSON OR AN AFFILIATE OR
                  ASSOCIATE OF AN ACQUIRING PERSON (AS SUCH TERMS ARE DEFINED IN
                  THE STOCKHOLDERS RIGHTS AGREEMENT) AND BY ANY SUBSEQUENT
                  HOLDER OF SUCH RIGHTS ARE NULL AND VOID AND NONTRANSFERABLE.


                                Right Certificate

                                   ALTEON INC.

                  This certifies that , or registered assigns, is the registered
owner of the number of Rights set forth above, each of which entitles the owner
thereof, subject to the terms, provisions and conditions of the Stockholders
Rights Agreement dated as of ____________, 1995 (the "Rights Agreement"),
between Alteon Inc., a Delaware corporation (the "Company"), and Registrar and
Transfer Company, as Rights Agent (the "Rights Agent"), unless the Rights
evidenced hereby shall have been previously redeemed by the Company, to purchase
from the Company at any time after the Distribution Date (as defined in the
Rights Agreement) and prior to 5:00 p.m., New York City time, on the 10th
anniversary of the date of the Rights Agreement (the "Expiration Date"), at the
principal office of the Rights Agent, or its successors as Rights Agent, one
one-thousandths (1/1,000ths) of a fully paid, nonassessable share of Series F
Preferred Stock, par value $0.01 per share, of the Company (the "Preferred
Shares"), at a purchase price per one one-thousandths (1/1,000ths) of a share
equal to $80.00 (the "Purchase Price") payable in cash, upon presentation and
surrender of this Right Certificate with the Form of Election to Purchase duly
executed.

                  The Purchase Price and the number and kind of shares which may
be purchased upon exercise of each Right evidenced by this Right Certificate, as
set forth above, are the Purchase Price and the number and kind of shares which
may be so purchased as of [ ]. As provided in the Rights Agreement, the Purchase
Price and the number and kind of shares which may be purchased upon the exercise
of each Right evidenced by this Right Certificate are subject to modification
and adjustment upon the happening of certain events.

                  If the Rights evidenced by this Right Certificate are at any
time beneficially owned by an Acquiring Person or an Affiliate or Associate of
an Acquiring Person (as such terms are defined in the Rights Agreement), such
Rights shall be null and void and nontransferable and the holder of any such
Right (including any purported transferee or subsequent holder) shall not have
any right to exercise or transfer any such Right.



                                       38
<PAGE>   42
                                                                     Exhibit 4.1

                  This Right Certificate is subject to all the terms, provisions
and conditions of the Rights Agreement, which terms, provisions and conditions
are hereby incorporated herein by reference and made a part hereof and to which
reference to the Rights Agreement is hereby made for a full description of the
rights, limitations of rights, obligations, duties and immunities hereunder of
the Rights Agent, the Company and the holders of the Right Certificates. Copies
of the Rights Agreement are on file at the above-mentioned office of the Rights
Agent and are also available from the Company upon written request.

                  This Right Certificate, with or without other Right
Certificates, upon surrender at the principal stock transfer or corporate trust
office of the Rights Agent, may be exchanged for another Right Certificate or
Right Certificates of like tenor and date evidencing Rights entitling the holder
to purchase a like aggregate number and kind of shares as the Rights evidenced
by the Right Certificate or Right Certificates surrendered shall have entitled
such holder to purchase. If this Right Certificate shall be exercised in part,
the holder shall be entitled to receive upon surrender hereof another Right
Certificate or Right Certificates for the number of whole Rights not exercised.

                  Subject to the provisions of the Rights Agreement, the Rights
evidenced by this Right Certificate may be redeemed by the Company at its option
at a redemption price (in cash or shares of Common Stock or other securities of
the Company deemed by the Board of Directors to be at least equivalent in value)
of $.01 per Right (which amount shall be subject to adjustment as provided in
the Rights Agreement) at any time prior to the earlier of (i) such time as a
Person becomes an Acquiring Person and (ii) the Expiration Date; provided,
however, that, for the 120-day period after any date of a change (resulting from
a proxy or consent solicitation) in a majority of the Board of Directors of the
Company in office at the commencement of such solicitation, the Rights may only
be redeemed if (A) there are directors then in office who were in office at the
commencement of such solicitation and (B) the Board of Directors of the Company,
with the concurrence of a majority of such directors then in office, determines
that such redemption is, in their judgment, in the best interests of the Company
and its stockholders.

                  The Company may, but shall not be required to, issue fractions
of Preferred Shares or distribute certificates which evidence fractions of
Preferred Shares upon the exercise of any Right or Rights evidenced hereby. In
lieu of issuing fractional shares, the Company may elect to make a cash payment
as provided in the Rights Agreement for fractions of a share other than one
one-thousandths (1/1,000ths) of a share or any integral multiple thereof or to
issue certificates or utilize a depository arrangement as provided in the terms
of the Rights Agreement and the Preferred Shares.

                  No holder of this Right Certificate shall be entitled to vote
or receive dividends or be deemed for any purpose the holder of the Preferred
Shares or of any other securities of the Company which may at any time be
issuable on the exercise hereof, nor shall anything contained in the Rights
Agreement or herein be construed to confer upon the holder thereof, as such, any
of the rights of a stockholder of the Company, including, without limitation,
any right to vote for the election of directors or upon any matter submitted to
stockholders at any meeting thereof, or to give or withhold consent to any
corporate action, or to receive notice of meetings or other actions affecting
stockholders (except as provided in the Rights Agreement), or to receive
dividends or other distributions or subscription rights, or otherwise, until the
Right or Rights evidenced by this Right Certificate shall have been exercised as
provided in accordance with the provisions of the Rights Agreement.

                                       39
<PAGE>   43
                                                                     Exhibit 4.1

                  This Right Certificate shall not be valid or obligatory for
any purpose until it shall have been countersigned by the Rights Agent.

                  WITNESS the facsimile signature of the proper officers of the
Company and its corporate seal.

Dated as of:

                                       ALTEON INC.,


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


Attest:


Name:
Title:



Countersigned:

Registrar and Transfer Company
as Rights Agent,


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



                                       40
<PAGE>   44
                                                                     Exhibit 4.1

                     [On Reverse Side of Right Certificate]

                          FORM OF ELECTION TO PURCHASE

                   (To be executed by the registered holder if
                   such holder desires to exercise the Rights
                     represented by this Right Certificate.)


To the Rights Agent:

                  The undersigned hereby irrevocably elects to exercise Rights
represented by this Right Certificate to purchase the Preferred Shares (or other
shares) issuable upon the exercise of such Rights and requests that certificates
for such shares be issued in the name of:

Please insert social security
or other identifying number



                         (Please print name and address)


                  If such number of Rights shall not be all the Rights evidenced
by this Right Certificate, a new Right Certificate for the balance remaining of
such Rights shall be registered in the name of and delivered to:

Please insert social security
or other identifying number



                         (Please print name and address)


Dated:                     , 19
         ------------------    ---




                                       Signature

Signature Guaranteed:


                                     NOTICE


                                       41
<PAGE>   45
                                                                     Exhibit 4.1

                  The signature on the foregoing Form of Election to Purchase
must correspond to the name as written upon the face of this Right Certificate
in every particular, without alteration or enlargement or any change whatsoever.




                                       42