<PAGE>   1
                                                                   EXHIBIT 10.28



                          $575,000,000 Principal Amount

                                IVAX CORPORATION

              4 1/2% Convertible Senior Subordinated Notes Due 2008

                          REGISTRATION RIGHTS AGREEMENT

May 4, 2001


UBS WARBURG LLC
299 Park Avenue
New York, New York 10171

Dear Sirs:

         IVAX Corporation, a Florida corporation (the "Company"), proposes to
issue and sell to UBS Warburg LLC, as initial purchaser (the "Initial
Purchaser"), upon the terms set forth in a purchase agreement dated May 1, 2001
(the "Purchase Agreement"), $575,000,000 aggregate principal amount of its 4
1/2% Convertible Senior Subordinated Notes due 2008 (the "Firm Notes"), which
will be convertible into Common Stock of the Company, par value $0.10 per share
(the "Conversion Shares"), as well as an additional allotment of up to
$150,000,000 initial principal amount of the same which the Initial Purchaser
may subsequently elect to purchase pursuant to the terms of the Purchase
Agreement (the "Additional Notes" and together with the Firm Notes, the
"Notes"). The Notes will be issued pursuant to an indenture, of even date
herewith (the "Indenture") between the Company and U.S. Bank Trust National
Association (the "Trustee"). As an inducement to the Initial Purchaser, the
Company agrees with the Initial Purchaser, for the benefit of the holders of the
Notes (including, without limitation, the Initial Purchaser) and Conversion
Shares (collectively, the "Securityholders"), as follows:

         1. Shelf Registration. (a) The Company shall file with the Securities
and Exchange Commission (the "Commission") within 90 days after the date hereof
(the "Closing Date") a single registration statement (the "Shelf Registration
Statement") on Form S-1 or Form S-3, if the use of such form is then available,
to cover resales of Transfer Restricted Securities (as defined below) by the
Holders (as defined below). The Company shall use its best efforts to cause the
Shelf Registration Statement to be declared effective by the Commission on or
prior to 180 days from the Closing Date. "Transfer Restricted Securities" means
each Note and any Conversion Share until the earlier of the (x) the date on
which such Note or Conversion Share has been effectively registered under the
Securities Act of 1933, as amended (the "Securities Act") and disposed of,
whether or not in accordance with the Shelf Registration Statement, and (y) the
date which is two years (or such shorter period of time as permitted by Rule
144(k) under the Securities Act (or any similar provisions then in force)) after



<PAGE>   2

the later of (A) the date of original issue of the Notes and (B) the last day
that the Company or any of its "affiliates" (as defined under the Securities
Act) was the owner of such Notes (or any predecessor thereto).

                  (b) The Company shall use its best efforts to cause the Shelf
         Registration Statement to be effective for a period of two years (or
         for such longer period if extended pursuant to Section 2(i)) from the
         effective date thereof or such shorter period that will terminate when
         each Transfer Restricted Security covered by the Shelf Registration
         Statement ceases to be a Transfer Restricted Security (the "Shelf
         Registration Period"). The Company shall be deemed not to have used its
         best efforts to keep the Shelf Registration Statement effective during
         the requisite period if it voluntarily takes any action that would
         result in Holders of Transfer Restricted Securities covered thereby not
         being able to offer and sell such Transfer Restricted Securities during
         that period, unless such action is required by applicable law or
         otherwise permitted hereunder, including, without limitation, by
         Section 2(i) hereof.

                  (c) Notwithstanding any other provisions of this Agreement to
         the contrary, the Company shall cause the Shelf Registration Statement
         and the related prospectus and any amendment or supplement thereto, as
         of the effective date of the Shelf Registration Statement, amendment or
         supplement, (i) to comply in all material respects with the applicable
         requirements of the Securities Act and the rules and regulations of the
         Commission and (ii) not to contain any untrue statement of a material
         fact or omit to state a material fact required to be stated therein or
         necessary in order to make the statements therein, in light of the
         circumstances under which they were made, not misleading, except that
         the foregoing shall not apply to any information provided to the
         Company by the Initial Purchaser or any Holder for inclusion in the
         Shelf Registration Statement.

         2. Registration Procedures. In connection with the proposed offer and
sale of the Transfer Restricted Securities in accordance with the methods of
distribution set forth in the Shelf Registration Statement (the "Shelf
Registration"), the following provisions apply:

                  (a) The Company shall prepare and mail to each Securityholder
         identified by the Initial Purchaser a questionnaire requesting such
         information regarding such Securityholder and the distribution of
         Transfer Restricted Securities as the Company may reasonably require
         for inclusion in the Shelf Registration Statement and asking each such
         Securityholder to confirm that it will comply with applicable
         securities laws, including the Securities Act and the rules and
         regulations promulgated thereunder. Each Securityholder to whom such
         questionnaire is mailed shall deliver a completed questionnaire
         together with its written confirmation to the Company within fifteen
         days of receipt. The Company will include in the Shelf Registration
         Statement as a selling security holder each Securityholder that returns
         its questionnaire and confirmation within fifteen days of receipt and
         will use reasonable efforts to include in the Shelf Registration
         Statement any Securityholder which fails to provide the Company with a
         completed questionnaire and confirmation within fifteen days of receipt
         but otherwise provides the completed questionnaire and confirmation
         prior to the commencement of the Shelf Registration Period. The Company
         shall have no obligation to include in the Shelf Registration Statement
         (whether by post-effective amendment, by prospectus supplement or
         otherwise) a Securityholder which fails to timely provide the Company
         with a completed questionnaire and confirmation. "Holder" means each
         Securityholder who (i) is so identified by the Initial Purchaser in
         writing within 5 business days after receipt by the Initial Purchaser



                                      -2-
<PAGE>   3

         of a written request by the Company and (ii) delivers to the Company a
         completed questionnaire containing the required information and
         confirmation within such fifteen-day period or is otherwise included as
         a selling security holder in the Shelf Registration Statement.

                  (b) The Company shall (i) furnish to the Initial Purchaser,
         prior to the filing thereof with the Commission, a copy of the Shelf
         Registration Statement and each amendment thereof and each supplement,
         if any, to the prospectus included therein and, in the event that the
         Initial Purchaser (with respect to any portion of an unsold allotment
         from the original offering) is participating in the Shelf Registration,
         the Company shall use its best efforts to reflect in each such
         document, when so filed with the Commission, such comments as the
         Initial Purchaser reasonably may propose; and (ii) include in such
         Shelf Registration Statement (or amendment or supplements) the names of
         the Holders who propose to sell Transfer Restricted Securities pursuant
         to the Shelf Registration Statement as selling securityholders.

                  (c) The Company shall give written notice to the Initial
         Purchaser and Holders of the Transfer Restricted Securities (which
         notice pursuant to clauses (ii)-(v) hereof shall be accompanied by an
         instruction to suspend the use of the prospectus contained in the Shelf
         Registration Statement (the "Prospectus") and any sales pursuant to
         such Prospectus until the requisite changes have been made):

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

                           (ii) of any request by the Commission for amendments
                  or supplements to the Shelf Registration Statement or the
                  Prospectus or for additional information;

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

                           (iv) of the receipt by the Company or its legal
                  counsel of any written notification with respect to the
                  suspension of the qualification of the Transfer Restricted
                  Securities for sale in any jurisdiction or the initiation or
                  threatening of any proceeding for such purpose; and

                           (v) of the happening of any event (but not the
                  details thereof) that requires the Company to make changes in
                  the Prospectus in order that the Prospectus does not contain
                  an untrue statement of a material fact nor omits to state a
                  material fact required to be stated therein or necessary to
                  make the statements therein, in light of the circumstances
                  under which they were made, not misleading.



                                      -3-
<PAGE>   4


         Any notice given hereunder shall be kept confidential and the recipient
of a notice agrees that neither they nor their affiliates will engage in any
unlawful transactions in the Company's securities based on the information
contained in such notice.

                  (d) The Company shall make every reasonable effort to obtain
         the withdrawal at the earliest possible time, of any order suspending
         the effectiveness of the Shelf Registration Statement.

                  (e) The Company shall furnish to each Holder of Transfer
         Restricted Securities included within the coverage of the Shelf
         Registration Statement, without charge, at least one copy of the Shelf
         Registration Statement and any post-effective amendment thereto,
         including financial statements and schedules, and, if the Holder so
         requests in writing, all exhibits thereto (including those, if any,
         incorporated by reference).

                  (f) The Company shall, during the Shelf Registration Period,
         deliver to each Holder of Transfer Restricted Securities included
         within the coverage of the Shelf Registration, without charge, as many
         copies of the Prospectus (including each preliminary Prospectus) and
         any amendment or supplement thereto as such person may reasonably
         request. The Company consents, subject to the provisions of this
         Agreement, to the use of the Prospectus or any amendment or supplement
         thereto by each of the selling Holders of the Transfer Restricted
         Securities covered by the Prospectus in connection with the offering
         and sale of the Transfer Restricted Securities covered by the
         Prospectus, or any amendment or supplement thereto, included in the
         Shelf Registration Statement.

                  (g) Prior to any public offering of the Transfer Restricted
         Securities pursuant to any Shelf Registration Statement, the Company
         shall use its best efforts to register or qualify or cooperate with the
         Holders of the Transfer Restricted Securities included therein and
         their respective counsel in connection with the registration or
         qualification or exemption from registration or qualification of the
         Transfer Restricted Securities included in the Shelf Registration
         Statement for offer and sale under the securities or "blue sky" laws of
         such states of the United States as any Holder of the Transfer
         Restricted Securities included in the Shelf Registration Statement
         reasonably requests in writing and do any and all other acts or things
         reasonably necessary or advisable to enable the offer and sale in such
         states of the Transfer Restricted Securities covered by such Shelf
         Registration Statement; provided, however, that the Company shall not
         be required to (i) qualify as a foreign corporation to do business in
         any jurisdiction where it is not then so qualified or (ii) take any
         action which would subject it to general service of process or to
         taxation in any jurisdiction where it is not then so subject or (iii)
         subject itself to taxation in any jurisdiction in which it is not now
         so subject.

                  (h) The Company shall cooperate with the Holders of the
         Transfer Restricted Securities to facilitate the timely preparation and
         delivery prior to settlement of any sales pursuant to the Shelf
         Registration Statement of certificates representing the Transfer
         Restricted Securities sold pursuant to the Shelf Registration Statement
         free of any restrictive legends and in such denominations and
         registered in such names as the Holders may request provided that such



                                      -4-
<PAGE>   5

         request is made a reasonable period of time prior to sales of the
         Transfer Restricted Securities pursuant to such Shelf Registration
         Statement.

                  (i) Upon the occurrence of any event contemplated by
         paragraphs (ii) through (v) of Section 2(c) above during the Shelf
         Registration Period, the Company shall promptly prepare and file a
         post-effective amendment to the Shelf Registration Statement or a
         supplement to the Prospectus and any other required document so that,
         as thereafter delivered to Holders of the Transfer Restricted
         Securities covered thereby or purchasers of Transfer Restricted
         Securities, the Prospectus will not contain an untrue statement of a
         material fact or omit to state any material fact required to be stated
         therein or necessary to make the statements therein, in light of the
         circumstances under which they were made, not misleading; provided,
         however, that the Company may delay preparing, filing and distributing
         any such supplement or amendment (such period of delay, a "Suspension
         Period") if the Company determines in good faith that the preparation
         or filing of such supplement or amendment would, in the reasonable
         judgment of the Company, (i) interfere with or affect any pending or
         contemplated corporate development (whether or not a final decision has
         been made with respect to such development) or (ii) involve initial or
         continuing disclosure obligations that are not in the best interests of
         the Company's shareholders at such time; provided, further, that such
         delay shall not extend for a period of more than 30 business days in
         any three-month period or more than 60 business days in any
         twelve-month period. If the Company notifies the Initial Purchaser and
         the Holders of the Transfer Restricted Securities in accordance with
         paragraphs (ii) through (v) of Section 2(c) above to suspend the use of
         the Prospectus until the requisite changes to the Prospectus have been
         made, then the Initial Purchaser and the Holders of the Transfer
         Restricted Securities shall suspend use of such Prospectus and the
         period of effectiveness of the Shelf Registration Statement provided
         for in Section 1(b) above shall be extended by the number of days from
         and including the date of the giving of such notice to and including
         the date when the Initial Purchaser and the Holders of the Transfer
         Restricted Security shall have received such amended or supplemented
         prospectus pursuant to this Section 2(i).

                  (j) Not later than the effective date of the Shelf
         Registration Statement, the Company will provide CUSIP numbers for the
         Notes and the Conversion Shares registered under the Shelf Registration
         Statement and provide the Trustee with a certificate for the Notes, in
         a form eligible for deposit with The Depository Trust Company, it being
         understood that such securities will continue to bear any appropriate
         restrictive legends.

                  (k) The Company will comply with all rules and regulations of
         the Commission to the extent and so long as they are applicable to the
         Shelf Registration Statement and will make generally available to its
         security holders (or otherwise provide in accordance with Section 11(a)
         of the Securities Act and Rule 158 thereunder) an earnings statement
         satisfying the provisions of Section 11(a) of the Securities Act and
         Rule 158 thereunder, no later than 45 days after the end of a 12-month
         period (or 90 days, if such period is a fiscal year) beginning with the
         first month of the Company's first fiscal quarter commencing after the


                                      -5-
<PAGE>   6

         effective date of the Shelf Registration Statement, which statement
         shall cover such 12-month period.

                  (l) The Company shall cause the Indenture to be qualified
         under the Trust Indenture Act of 1939, as amended, in a timely manner
         and containing such changes, if any, as shall be necessary or desirable
         for such qualification. In the event that such qualification would
         require the appointment of a new trustee under the Indenture, the
         Company shall appoint a new trustee thereunder pursuant to the
         applicable provisions of the Indenture.

                  (m) In addition to the questionnaire and confirmation provided
         for by Section 2(a) above, the Company may require each Holder of
         Transfer Restricted Securities to be sold pursuant to the Shelf
         Registration Statement to furnish to the Company such information
         regarding the Holder and the distribution of the Transfer Restricted
         Securities as the Company may from time to time reasonably require for
         inclusion in the Shelf Registration Statement, and the Company may
         exclude from the Shelf Registration Statement the Transfer Restricted
         Securities of any Holder that fails to furnish such information
         promptly after receiving such request.

                  (n) The Company shall enter into such customary agreements
         (including, if requested, an underwriting agreement in customary form)
         and take all such other action, if any, as any Holder which, together
         with its "affiliates" (as defined in the Securities Act), holds
         $40,000,000 or greater in aggregate initial principal amount of the
         Transfer Restricted Securities and which, together with its affiliates,
         intends to sell at least $40,000,000 in initial aggregate principal
         amount of Transfer Restricted Securities in an underwritten offering,
         shall reasonably request in order to facilitate the disposition of the
         Transfer Restricted Securities pursuant to the Shelf Registration
         Statement; provided, that in no event shall the Company be required to
         cause any representatives to attend any informational or roadshow
         presentations or pay any expenses related thereto.

                  (o) The Company shall, subject to the execution and delivery
         to the Company of any confidentiality agreements that the Company may
         reasonably request (i) make reasonably available for inspection by the
         Holders, any underwriter participating in any disposition of Transfer
         Restricted Securities pursuant to the Shelf Registration Statement and
         any attorney, accountant or other agent retained by the Holders or any
         such underwriter all relevant financial and other records, corporate
         documents and properties of the Company and (ii) cause the Company's
         officers, directors, employees, accountants and auditors to supply all
         relevant information reasonably requested by the Holders or any such
         underwriter, attorney, accountant or agent in connection with the Shelf
         Registration Statement, in each case, as shall be reasonably necessary
         to enable such persons, to conduct a reasonable investigation within
         the meaning of Section 11 of the Securities Act; provided, however,
         that the foregoing inspection and information gathering shall be
         coordinated on behalf of the Initial Purchaser and the other parties by
         one firm of counsel, which firm shall be Willkie Farr & Gallagher until
         another firm shall be designated as described in Section 3 hereof.



                                      -6-
<PAGE>   7


                  (p) The Company, if requested by any Holder of the Transfer
         Restricted Securities referred to in paragraph (n) above, shall cause
         (i) its counsel to deliver an opinion relating to the Transfer
         Restricted Securities in customary form addressed to such Holder and
         the managing underwriters, if any, thereof and dated, in the case of
         the initial opinion, the effective date of such Shelf Registration
         Statement covering the matters customarily covered in underwritten
         offerings, (ii) its counsel to deliver a statement in customary form
         relating to the compliance as to form of such Shelf Registration
         Statement (but not any documents incorporated by reference therein) and
         of the Indenture with the requirements of the Securities Act and the
         Trust Indenture Act, respectively; and, as of the date of the opinion
         and as of the effective date of the Shelf Registration Statement or
         most recent post-effective amendment thereto, as the case may be that
         no fact had come to such counsel's attention in connection with the
         preparation of the Shelf Registration Statement causing such counsel to
         believe that such Shelf Registration Statement and the Prospectus, as
         then amended or supplemented (but not any documents incorporated by
         reference therein), contained an untrue statement of a material fact or
         omitted to state therein a material fact required to be stated therein
         or necessary to make the statements therein, in light of the
         circumstances under which such statements were made, not misleading;
         (iii) its officers to execute and deliver all customary documents and
         certificates and updates thereof requested by any underwriters of the
         applicable Transfer Restricted Securities; and (iv) its independent
         public accountants and the independent public accountants, if any, with
         respect to any other entity for which financial information is provided
         in the Shelf Registration Statement to provide to the selling Holder(s)
         of the applicable Transfer Restricted Securities and any underwriter
         therefor a comfort letter in customary form and covering matters of the
         type customarily covered in comfort letters in connection with primary
         underwritten offerings, subject to receipt of appropriate documentation
         as contemplated, and only if permitted, by Statement of Auditing
         Standards No. 72.

                  (q) In the event that any broker-dealer registered under the
         Exchange Act shall underwrite any Transfer Restricted Securities or
         participate as a member of an underwriting syndicate or selling group
         or "assist in the distribution" (within the meaning of the Conduct
         Rules (the "Rules") of the National Association of Securities Dealers,
         Inc. ("NASD")) thereof, whether as a Holder of such Transfer Restricted
         Securities or as an underwriter, a placement or sales agent or a broker
         or dealer in respect thereof, or otherwise, the Company, if requested
         by such broker-dealer, will assist such broker-dealer in complying with
         the requirements of such Rules, including, without limitation, by (i)
         if such Rules, including Rule 2720, shall so require, engaging a
         "qualified independent underwriter" (as defined in Rule 2720) to
         participate in the preparation of the Shelf Registration Statement
         relating to such Transfer Restricted Securities, to exercise usual
         standards of due diligence in respect thereto and, if any portion of
         the offering contemplated by such Shelf Registration Statement is an
         underwritten offering or is made through a placement or sales agent, to
         recommend the yield of such Transfer Restricted Securities, (ii)
         indemnifying any such qualified independent underwriter to the extent
         of the indemnification of underwriters provided in Section 4 hereof and
         (iii) providing such information to such broker- dealer as may be
         required in order for such broker-dealer to comply with the
         requirements of the Rules.



                                      -7-
<PAGE>   8


                  (r) The Company shall use its best efforts to take all other
         steps necessary to effect the registration of the Transfer Restricted
         Securities covered by the Shelf Registration Statement contemplated
         hereby.

         3. Registration Expenses. The Company shall bear all fees and expenses
incurred in connection with the performance of its obligations under Sections 1
and 2 hereof whether or not the Shelf Registration Statement is filed or becomes
effective, shall bear or reimburse the Holders of the Transfer Restricted
Securities covered thereby for the reasonable fees and disbursements of one firm
of counsel, which firm shall be Willkie Farr & Gallagher until another firm
shall be designated by the Holders of a majority in initial principal amount of
the Notes covered thereby to act as counsel for the Holders in connection
therewith. The Holders shall be responsible for all other fees and expenses,
such as brokerage fees, underwriting discounts and commissions.

         4. Indemnification. (a) To the extent permitted by law, the Company
agrees to indemnify and hold harmless each Holder of Transfer Restricted
Securities covered by the Shelf Registration Statement and each person, if any,
who controls such Holder within the meaning of the Securities Act or the
Exchange Act (each Holder and such controlling persons are referred to
collectively as the "Indemnified Parties") from and against any losses, claims,
damages or liabilities, joint or several, or any actions in respect thereof
(including, but not limited to, any losses, claims, damages, liabilities or
actions relating to purchases and sales of the Transfer Restricted Securities)
to which each Indemnified Party may become subject under the Securities Act, the
Securities Exchange Act of 1934, as amended (the "Exchange Act") or otherwise,
insofar as such losses, claims, damages, liabilities or actions arise out of or
are based upon any untrue statement or alleged untrue statement of a material
fact contained in the Shelf Registration Statement or Prospectus or in any
amendment or supplement thereto or in any preliminary Prospectus included in the
Shelf Registration Statement, or arise out of, or are based upon, the omission
or alleged omission to state therein a material fact required to be stated
therein or necessary to make the statements therein not misleading, in light of
the circumstances under which such statements were made, and shall reimburse, as
incurred, the Indemnified Parties for any legal or other expenses reasonably
incurred by them in connection with investigating or defending any such loss,
claim, damage, liability or action in respect thereof; provided, however, that
(i) the Company shall not be liable in any such case to the extent that such
loss, claim, damage or liability arises out of or is based upon any untrue
statement or alleged untrue statement or omission or alleged omission made in
the Shelf Registration Statement or Prospectus or in any amendment or supplement
thereto or in any preliminary Prospectus included in the Shelf Registration
Statement in reliance upon and in conformity with written information pertaining
to the Initial Purchaser or such Holder and furnished to the Company by or on
behalf of the Initial Purchaser or Holder specifically for inclusion therein and
(ii) with respect to any untrue statement or omission or alleged untrue
statement or omission made in any preliminary Prospectus included in the Shelf
Registration Statement, the indemnity agreement contained in this subsection (a)
shall not inure to the benefit of any Holder from whom the person asserting any
such losses, claims, damages or liabilities purchased the Transfer Restricted
Securities concerned, to the extent that a prospectus relating to such Transfer
Restricted Securities was required to be delivered by such Holder under the
Securities Act in connection with such purchase and any such loss, claim, damage
or liability of such Holder results from the fact that there was not sent or
given to such person, at or prior to the written confirmation of the sale of
such Transfer Restricted Securities to such person, a copy of the final



                                      -8-
<PAGE>   9

Prospectus if the Company had previously furnished copies thereof to such
Holder; provided further, however, that this indemnity agreement will be in
addition to any liability which the Company may otherwise have to such
Indemnified Party. The Company shall also indemnify underwriters, their officers
and directors and each person who controls such underwriters within the meaning
of the Securities Act or the Exchange Act to the same extent as provided above
with respect to the indemnification of the Holders of the Transfer Restricted
Securities if requested by such Holders.

                  (b) To the extent permitted by law, each Holder of the
         Transfer Restricted Securities covered by the Shelf Registration
         Statement severally and not jointly, will indemnify and hold harmless
         the Company and each person, if any, who controls the Company within
         the meaning of the Securities Act or the Exchange Act from and against
         any losses, claims, damages or liabilities or any actions in respect
         thereof, to which the Company or any such controlling person may become
         subject under the Securities Act, the Exchange Act or otherwise,
         insofar as such losses, claims, damages, liabilities or actions arise
         out of or are based upon any untrue statement or alleged untrue
         statement of a material fact contained in the Shelf Registration
         Statement or Prospectus or in any amendment or supplement thereto or in
         any preliminary Prospectus included in the Shelf Registration
         Statement, or arise out of or are based upon the omission or alleged
         omission to state therein a material fact necessary to make the
         statements therein not misleading, but in each case only to the extent
         that the untrue statement or omission or alleged untrue statement or
         omission was made in reliance upon and in conformity with written
         information pertaining to such Holder and furnished to the Company by
         or on behalf of such Holder specifically for inclusion therein; and,
         subject to the limitation set forth immediately preceding this clause,
         shall reimburse, as incurred, the Company for any legal or other
         expenses reasonably incurred by the Company or any such controlling
         person in connection with investigating or defending any loss, claim,
         damage, liability or action in respect thereof. This indemnity
         agreement will be in addition to any liability which such Holder may
         otherwise have to the Company or any of its controlling persons.

                  (c) Promptly after receipt by an indemnified party under this
         Section 4 of notice of the commencement of any action or proceeding
         (including a governmental investigation), such indemnified party will,
         if a claim in respect thereof is to be made against the indemnifying
         party under this Section 4, notify the indemnifying party of the
         commencement thereof; but the omission so to notify the indemnifying
         party will not, in any event, relieve the indemnifying party from any
         obligations to any indemnified party. In case any such action is
         brought against any indemnified party, and it notifies the indemnifying
         party of the commencement thereof, the indemnifying party will be
         entitled to participate therein and, to the extent that it may wish,
         jointly with any other indemnifying party similarly notified, to assume
         the defense thereof, with counsel reasonably satisfactory to such
         indemnified party (which may be counsel for the indemnifying party)
         unless such indemnified party shall have been advised by counsel that
         there may be one or more defenses reasonably available to such
         indemnified party that are in conflict with the defenses available to
         the indemnifying party or its affiliates or controlling persons, and
         after notice from the indemnifying party to such indemnified party of
         its election so to assume the defense thereof the indemnifying party
         will not be liable to such indemnified party under this Section 4 for
         any legal or other expenses, other than reasonable costs of
         investigation, subsequently incurred by such indemnified party in



                                      -9-
<PAGE>   10

         connection with the defense thereof. No indemnifying party shall,
         without the prior written consent of the indemnified party, effect any
         settlement of any pending or threatened action in respect of which any
         indemnified party is or could have been a party and indemnity could
         have been sought hereunder by such indemnified party unless such
         settlement includes an unconditional release of such indemnified party
         from all liability on any claims that are the subject matter of such
         action. An indemnifying party will not be liable for any settlement of
         any action or claim effected without its written consent; provided,
         however, that such consent will not be reasonably withheld.

                  (d) If the indemnification provided for in this Section 4 is
         unavailable or insufficient to hold harmless an indemnified party under
         subsections (a) or (b) above, then each indemnifying party shall
         contribute to the amount paid or payable by such indemnified party as a
         result of the losses, claims, damages or liabilities (or actions in
         respect thereof) referred to in subsection (a) or (b) above (i) in such
         proportion as is appropriate to reflect the relative benefits received
         by the indemnifying party or parties on the one hand and the
         indemnified party on the other from the sale of the Transfer Restricted
         Securities, pursuant to the Shelf Registration Statement, or (ii) if
         the allocation provided by the foregoing clause (i) is not permitted by
         applicable law, in such proportion as is appropriate to reflect not
         only the relative benefits referred to in clause (i) above but also the
         relative fault of the indemnifying party or parties on the one hand and
         the indemnified party on the other in connection with the statements or
         omissions that resulted in such losses, claims, damages or liabilities
         (or actions in respect thereof) as well as any other relevant equitable
         considerations. The relative fault of the parties shall be determined
         by reference to, among other things, whether the untrue or alleged
         untrue statement of a material fact or the omission or alleged omission
         to state a material fact relates to information supplied by the Company
         on the one hand or such Holder or such other indemnified party, as the
         case may be, on the other, and the parties' relative intent, knowledge,
         access to information and opportunity to correct or prevent such
         statement or omission. The amount paid by an indemnified party as a
         result of the losses, claims, damages or liabilities referred to in the
         first sentence of this subsection (d) shall be deemed to include any
         legal or other expenses reasonably incurred by such indemnified party
         in connection with investigating or defending any action or claim which
         is the subject of this subsection (d). Notwithstanding any other
         provision of this Section 4(d), the Holders of the Transfer Restricted
         Securities shall not be required to contribute any amount in excess of
         the amount by which the net proceeds received by such Holders from the
         sale of the Transfer Restricted Securities pursuant to the Shelf
         Registration Statement exceeds the amount of damages which such Holders
         have otherwise been required to pay by reason of such untrue or alleged
         untrue statement or omission or alleged omission. No person guilty of
         fraudulent misrepresentation (within the meaning of Section 11(f) of
         the Securities Act) shall be entitled to contribution from any person
         who was not guilty of such fraudulent misrepresentation. For purposes
         of this paragraph (d), each person, if any, who controls such
         indemnified party within the meaning of the Securities Act or the
         Exchange Act shall have the same rights to contribution as such
         indemnified party and each person, if any, who controls the Company
         within the meaning of the Securities Act or the Exchange Act shall have
         the same rights to contribution as the Company.



                                      -10-
<PAGE>   11

                  (e) The agreements contained in this Section 4 shall survive
         the sale of the Transfer Restricted Securities pursuant to the Shelf
         Registration Statement and shall remain in full force and effect,
         regardless of any termination or cancellation of this Agreement or any
         investigation made by or on behalf of any indemnified party.

         5. Liquidated Damages Under Certain Circumstances. If (i) the Shelf
Registration Statement is not filed with the Commission on or prior to 90 days
after the Closing Date, (ii) the Shelf Registration Statement has not been
declared effective by the Commission within 180 days after the Closing Date or
(iii) the Shelf Registration Statement is filed and declared effective but shall
thereafter during the Shelf Registration Period cease to be effective (without
being succeeded immediately by an additional registration statement filed and
declared effective) or usable for the offer and sale of Transfer Restricted
Securities for a period of time (including any Suspension Period) which shall
exceed 60 days in the aggregate in any 12-month period (each such event referred
to in clauses (i) through (iii), a "Registration Default"), the Company will pay
liquidated damages to each Holder of Transfer Restricted Securities that timely
complied with the requirements of Section 2(a). The amount of liquidated damages
payable during any period during which a Registration Default shall have
occurred and be continuing is that amount which is equal to one-quarter of one
percent (25 basis points) per annum per $1,000 initial principal amount and, if
applicable, on an equivalent basis per Conversion Share (subject to adjustment
in the event of stock splits, stock recombinations, stock dividends and the
like) constituting Transfer Restricted Securities for each 90-day period until
the applicable registration statement is filed and the applicable Registration
Default has been cured, up to a maximum amount of liquidated damages of
three-quarters of one percent (75 basis points) per annum per $1,000 initial
principal amount of Notes and, if applicable, on an equivalent basis per
Conversion Share (subject to adjustment as set forth above) constituting
Transfer Restricted Securities. All accrued liquidated damages shall be paid to
Holders of record entitled to receive such payments by wire transfer of
immediately available funds or by federal funds check by the Company on the
regular interest payment date. Following the cure of all Registration Defaults
or, if earlier, the termination of the Shelf Registration Period, liquidated
damages will cease to accrue with respect to such Registration Default.

         6. Rules 144 and 144A. The Company shall use its best efforts to file
the reports required to be filed by it under the Securities Act and the Exchange
Act in a timely manner and, if at any time the Company is not required to file
such reports, it will, upon the request of any Holder of Notes, make publicly
available other information so long as necessary to permit sales of their
securities pursuant to Rules 144 and 144A. The Company covenants that it will
take such further action as any Holder of Notes may reasonably request, all to
the extent required from time to time to enable such Holder to sell Notes
without registration under the Securities Act within the limitation of the
exemptions provided by Rules 144 and 144A (including the requirements of Rule
144A(d)(4)). The Company will provide a copy of this Agreement to prospective
purchasers of Notes identified to the Company by the Initial Purchaser upon
request. Upon the request of any Holder of Notes, the Company shall deliver to
such Holder a written statement as to whether it has complied with such
requirements. Notwithstanding the foregoing, nothing in this Section 6 shall be
deemed to require the Company to register any of its securities pursuant to the
Exchange Act.



                                      -11-
<PAGE>   12

         7. Underwritten Registrations. If any of the Transfer Restricted
Securities covered by the Shelf Registration Statement are to be sold in an
underwritten offering, the investment banker or investment bankers and manager
or managers that will administer the offering ("Managing Underwriters") will be
selected by the Company; provided, that such selection is consented to by the
Holders of a majority in aggregate initial principal amount of Transfer
Restricted Securities to be included in such offering, which consent shall not
be unreasonably withheld or delayed. No person may participate in any
underwritten registration hereunder unless such person (i) agrees to sell such
person's Transfer Restricted Securities on the basis provided in any
underwriting arrangements approved by the persons entitled hereunder to approve
such arrangements and (ii) completes and executes all questionnaires, powers of
attorney, indemnities, underwriting agreements and other documents reasonably
required under the terms of such underwriting arrangements.

         8. Miscellaneous.

                  (a) Amendments and Waivers. The provisions of this Agreement
         may not be amended, modified or supplemented, and waivers or consents
         to departures from the provisions hereof may not be given, except by
         the Company and the written consent of the Holders of a majority in
         initial principal amount of the Transfer Restricted Securities affected
         by such amendment, modification, supplement, waiver or consents.

                  (b) Notices. All notices and other communications provided for
         or permitted hereunder shall be made in writing by hand delivery,
         first-class mail, facsimile transmission, or overnight air courier:

                      (1)   if to a Holder of the Transfer Restricted
                            Securities, at the most current address given by
                            such Holder to the Company in writing.

                      (2)   if to the Initial Purchaser:

                            UBS Warburg LLC
                            299 Park Avenue
                            New York, NY 10171
                            Fax No.: (212) 821-2446
                            Attention: Syndicate Department

                            with a copy to:

                            Willkie Farr & Gallagher
                            787 7th Avenue
                            New York, NY 10019
                            Fax No.: (212) 728-8111
                            Attention:  William J. Grant, Esq.




                                      -12-
<PAGE>   13




                      (3)   if to the Company, at its address as follows:

                            IVAX Corporation
                            44 Biscayne Boulevard
                            Miami, FL  33137
                            Fax No.: (305) 575-6049
                            Attention: Chief Legal Officer

                            with a copy to:

                            Akerman Senterfitt & Eidson, P.A.
                            One S.E. Third Avenue
                            Miami, FL  33131
                            Fax No.: (305) 374-5095
                            Attention:  Kara MacCullough, Esq.

         All such notices and communications shall be deemed to have been duly
given: at the time delivered by hand, if personally delivered; three business
days after being deposited in the mail, postage prepaid, if mailed; when receipt
is acknowledged by recipient's facsimile machine operator, if sent by facsimile
transmission; and on the day delivered, if sent by overnight air courier.

                  (c) No Conflicting Agreements. The Company has not, as of the
         date hereof, entered into, nor shall it, on or after the date hereof,
         enter into, any agreement with respect to its securities that conflicts
         with the provisions hereof.

                  (d) Successors and Assigns. This Agreement shall be binding
         upon the Company and each Holder of Transfer Restricted Securities and
         their respective successors and assigns.

                  (e) Counterparts. This Agreement may be executed in any number
         of counterparts and by the parties hereto in separate counterparts,
         each of which when so executed shall be deemed to be an original and
         all of which taken together shall constitute one and the same
         agreement. Delivery of an executed counterpart by facsimile shall be
         effective as delivery of a manually executed counterpart thereof.

                  (f) Headings. The headings in this Agreement are for
         convenience of reference only and shall not limit or otherwise affect
         the meaning hereof.

                  (g) Governing Law. THIS AGREEMENT SHALL BE GOVERNED BY, AND
         CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK WITHOUT
         REGARD TO PRINCIPLES OF CONFLICTS OF LAWS.

                  (h) Severability. If any one or more of the provisions
         contained herein, or the application thereof in any circumstance, is
         held invalid, illegal or unenforceable, the validity, legality and
         enforceability of any such provision in every other respect and of the



                                      -13-
<PAGE>   14

         remaining provisions contained herein shall not be affected or impaired
         thereby.

                  (i) Transfer Restricted Securities Held by the Company.
         Whenever the consent or approval of Holders of a specified percentage
         of initial principal amount of Transfer Restricted Securities is
         required hereunder, Transfer Restricted Securities held by the Company
         or its affiliates (other than subsequent Holders of Transfer Restricted
         Securities if such subsequent Holders are deemed to be affiliates
         solely by reason of their holdings of such Transfer Restricted
         Securities) shall not be counted in determining whether such consent or
         approval was given by the Holders of such required percentage.



                                      -14-
<PAGE>   15


         If the foregoing is in accordance with your understanding of our
agreement, please sign and return to the Company a counterpart hereof, whereupon
this instrument, along with all counterparts, will become a binding agreement on
the Initial Purchaser and the Company in accordance with its terms.

Very truly yours,

IVAX CORPORATION

By:  /s/ THOMAS E. BEIER
     ----------------------------------
      Name: Thomas E. Beier
      Title: Chief Financial Officer



Accepted and agreed to as
of the date first above written



UBS WARBURG LLC

By:  /s/ BENJAMIN D. LORELLO
     ----------------------------------
      Name: Benjamin D. Lorello
      Title: Managing Director


By:  /s/ STEVEN MEEHAN
     ----------------------------------
     Name: Steven Meehan
     Title: Managing Director



                                      -15-