<PAGE>   1
               Certain confidential information has been omitted
                   and filed separately with the Commission.


                                                                    Exhibit 10.2
                    GLOBAL MANUFACTURING AND SUPPLY AGREEMENT


     This MANUFACTURING AND SUPPLY AGREEMENT ("Agreement") is made as of July 3,
2000 (the "Effective Date"), between RENAGEL LLC, a Delaware limited liability
company ("Customer") and WATSON LABORATORIES, INC. - NEW YORK, a New York
corporation ("Watson").

RECITALS:

A. Watson owns and operates a pharmaceutical manufacturing and packaging
facility located at 33 Ralph Avenue, Copiague, New York, and wishes to perform
certain manufacturing and packaging services for Customer.

B. Customer requires a manufacturer to perform the following manufacturing and
analytical testing services: compounding, encapsulating, packaging, analytical
and stability testing; and Watson is willing to perform such services for and on
behalf of Customer, all subject to the terms and conditions of this Agreement.

     NOW, THEREFORE, in consideration of the promises contained herein and other
valuable considerations, and intending to be bound hereby, the parties agree as
follows:

1. DEFINITIONS.

     1.1 DEFINITIONS. As used in this Agreement, the following terms shall have
the corresponding meanings set forth below:

        (a) "API" means sevelamer hydrochloride as described in the API
Specifications in EXHIBIT A hereto, with such amendments thereto as the parties
may from time to time approve in writing.

        (b) "API SPECIFICATIONS" means the specifications for the API as
described in EXHIBIT A, with such amendments thereto as the parties may from
time to time approve in writing.

        (c) "CAPSULES" mean the 403 mg capsules to be manufactured by Watson
and which will form part of the Final Product.

        (d) "CONFIDENTIALITY AGREEMENT" means that certain Confidentiality
Agreement dated January 1, 2000 between Customer and Watson.

        (e) "FINAL PRODUCT" means the finished product in 403 mg capsule form
and any packaging and labeling that may be required in a particular territory
or country in the Territory, all as described in the Final Specifications in
EXHIBIT B hereto, with such amendments thereto as the parties may from time to
time approve in writing.

        (f) "FINAL SPECIFICATIONS" means the production and quality control
specifications for the Final Product, all as set forth in EXHIBIT C hereto with
such amendments thereto as the parties may from time to time approve in writing.

                                        1

<PAGE>   2

        (g) "GMPs" means the current Good Manufacturing Practices for medicinal
products as described in the regulations of the specific country in the
Territory in which Final Product will be sold. (See EXHIBIT D).

        (h) "PPI" means the Producer Price Index for finished pharmaceutical
preparations, ethical, as published by the Bureau of Labor Statistics of the
U.S. Department of Labor, an example of which is set forth in EXHIBIT E.

        (i) "PRODUCTION FACILITY" means the facility of Watson located in
Copiague, New York.

        (j) "PRODUCTION PROCEDURES" means the procedures used to compound and
encapsulate the API into Capsules and package the Capsules in the form of Final
Product, conducted in accordance with GMPs and Watson's standard operating
procedures as provided to Customer.

        (k) "REGULATORY STANDARDS" means (i) the facility license requirements
of the regulatory agencies applicable to the Production Facility or Watson's
production, storage or handling of API or Final Product at the Production
Facility, (ii) any standards and regulations of any governmental authority that
apply to the Production Facility or Watson's storage or handling of API or Final
Product, and (iii) any standards and regulations of any governmental authority
that apply to the manufacture, packaging, labeling and release of the Final
Product.

        (l) "TECHNICAL AGREEMENT" means the Technical Agreement for the
Commercial Manufacture and Testing of Renagel(R) Drug Product applicable to the
particular territory and/or country of the Territory, forms of which are
attached hereto in EXHIBIT F. Additional Technical Agreements may be added by
mutual agreement of the parties. The terms and conditions of each Technical
Agreement are incorporated herein by reference. In the event of any conflict
between the terms of any Technical Agreement and this Agreement, the terms of
this Agreement shall govern.

        (m) "TERRITORY" means the countries as listed in EXHIBIT G hereto, as
from time to time amended by the parties in writing.

2.0 TERMS OF ENGAGEMENT.

     2.1 Subject to the provisions of this Agreement, Customer hereby appoints
Watson as a non-exclusive manufacturer of the Final Product for the Territory,
and Watson hereby accepts such appointment and agrees to act as such
non-exclusive manufacturer. The parties expressly agree that as of the Effective
Date, this Agreement shall replace and supersede any prior agreement between the
parties or their predecessors concerning manufacture and supply of Final Product
anywhere in the Territory. The parties specifically agree that the Manufacturing
and Supply Agreement, dated July 31, 1998, between RenaGel(R) LLC and Circa
Pharmaceuticals, Inc. is hereby terminated and of no further effect, without
obligation of either party (except for liabilities and obligations accrued as of
the date hereof).

     2.2 Customer agrees that the annual minimum number of Capsules which
Customer is obligated to order and purchase from Watson during each calendar
year during the term of this


                                       2


<PAGE>   3
 Agreement shall be equal to [*] during such calendar year.

     2.3 For purposes of the Agreement, Customer shall supply, or cause its
contract manufacturer to supply, Watson with sufficient quantities of tested and
released API which meet the API Specifications, [*]. All other materials
required for the production, packaging and shipping of the Final Product for
Customer will be supplied by Watson as per EXHIBIT H, and the parties
acknowledge that the cost of such materials is included in the batch pricing
listed on EXHIBIT I. [*]. Watson agrees that the labels utilized in packaging
the Final Product will conform to the label copy provided by Customer for the
country specified on Customer's purchase order for such Final Product.

     2.4 Watson agrees that it will use reasonable commercial efforts to
minimize the API waste associated with the manufacture of Final Product and to
achieve a yield for the API of [*] (the "Target Yield"). For each batch, Watson
shall calculate the actual yield achieved. Such calculation shall be subject to
confirmation by Customer, and Watson shall provide Customer with such
information as may be necessary for Customer to confirm such calculation. Within
forty-five (45) days after the end of each calendar semi-annual period (i.e.,
the six months ending June 30 and December 31), Customer shall calculate the
actual yield during such calendar semi-annual period. Such calculation shall be
subject to confirmation by Watson, and the parties shall provide each other with
such information as may be necessary to confirm such calculation. If the
semi-annual actual yield is lower than the Target Yield, Watson shall compensate
Customer as calculated in the manner described in EXHIBIT J. [*] If Customer
does not notify Watson of a claim for compensation within forty-five (45) days
after the end of a calendar semi-annual period, then no such compensation shall
be claimed regardless of actual yield. Should the average actual yield over [*]
consecutive batches (i.e. sum of average yield per batch divided by [*] be less
than [*], Customer may terminate this Agreement pursuant to Section 15.2. [*].

     2.5 Prior to the execution of this Agreement, Customer purchased an Index
K90i hard shell capsule filling machine (the "K90i"). The K90i has been
delivered to the Production Facility and Watson shall use the K90i solely for
the purpose of manufacturing Final Product for Customer under the terms of this
Agreement or manufacturing other products for Customer. Notwithstanding Watson's
use of the K90i, Customer shall at all times remain the owner of the K90i.
Watson shall, at its expense, provide normal preventative maintenance of the
K90i in a manner consistent with the way in which it services and maintains the
machinery located at the Production Facility and owned by Watson. In addition,
Watson shall provide non-routine maintenance, service and parts for the K90i,
and if Watson has performed normal preventative maintenance, Customer shall
reimburse Watson's expenses in excess of [*] for such non-routine maintenance,
service and parts during the term of this Agreement. At such time as Watson is
no longer producing Final Product for Customer under this Agreement or other
products manufactured by Watson for Customer, Customer


* Confidential information omitted and filed separately with the Commission.


                                       3


<PAGE>   4
shall have the right to enter the Production Facility on reasonable notice
during normal business hours and in a workmanlike manner remove the K90i.

3.0 MANUFACTURE OF FINAL PRODUCT

     3.1 During the term of this Agreement, Watson shall receive API from
Customer or Customer's contract manufacturer and shall sample such API in
accordance with Exhibit K and shall test such API to ensure conformance with the
Specifications set forth in EXHIBIT A. Upon receipt, Watson shall store API in
accordance with Regulatory Standards. Watson shall complete the testing of API
within fifty (50) days of its receipt. If Watson determines that the API does
not conform to the API Specifications or if the shipment of API contains a
quantity of API that is less than the reported or expected amount, Watson shall
provide written notice to Customer of such defect, nonconformance and/or
shortage within fifty-five (55) days of Watson's receipt of the API.

     3.2 During the term of this Agreement, Watson will manufacture and deliver
to Customer the Final Product ordered by Customer pursuant to the terms of this
Agreement. All Final Product shall be produced at the Production Facility. All
Final Product produced by Watson under this Agreement shall be produced in
accordance with the Production Procedures, the Final Specifications, GMPs and
all other applicable Regulatory Standards, and the applicable Technical
Agreement.

4.0 PRICE AND PAYMENT TERMS.

     4.1 Fees, prices and payment terms shall be in accordance with the
provisions as set forth in EXHIBIT I. The fees and prices set forth in EXHIBIT I
are as of October 1, 1999 and do not reflect adjustment, if any, to occur as of
January 1, 2000. Such adjustment, if any, will occur after the relevant
(December 1999) PPI information is finalized.

     4.2 As of January 1 of each year during the term of this Agreement, the
Prices set forth in EXHIBIT I shall be increased or decreased by the [*].

     4.3 Except as set forth in Section 13.4, payment for each delivery of the
Final Product to Customer will be made within thirty (30) days after the date of
Watson's invoice, to be rendered concurrently with delivery of the Final
Product. All payments required to be paid hereunder shall be made by corporate
check or by wire transfer of immediately available funds to the financial
institution, account number, and account party's name designated in writing by
Watson to Customer at the place of payment.


* Confidential information omitted and filed separately with the Commission.


                                       4

<PAGE>   5

     4.4 Customer shall reimburse Watson for any federal, state, or local excise
or other tax or assessment, which Watson may be required to pay upon the sale,
production, transportation, or use of the Final Product (excluding taxes based
on Watson's income or Watson's franchise fees or taxes).

     4.5 In the event that Customer requires any change in the Final Product,
production, testing or supply procedures, or Final Specifications, whether
pursuant to the Technical Agreement or otherwise, the parties shall negotiate in
good faith adjustments to the amounts payable hereunder and/or reimbursement of
Watson for non-recurring expenses.

5.0 RESPONSIBILITIES OF CUSTOMER.

     5.1 Customer will provide the API pursuant to Section 2.3, Final Product
Forecasts and Purchase Orders as outlined in Section 9.0, and will supply the
API Specifications and the Final Specifications and all necessary quality
control test specifications for the Final Product, which must be approved by
Watson (which approval will not be unreasonably withheld or delayed).

     5.2 Customer represents that Watson is not required to maintain a dedicated
facility for the manufacture of the Final Product.

     5.3 Customer shall be responsible for recalls.

6.0 RESPONSIBILITIES OF WATSON; WARRANTIES.

     6.1 Watson represents and warrants that the testing of the API will conform
to the applicable requirements of the Regulatory Standards and that the API will
be stored and controlled by Watson in accordance with applicable Regulatory
Standards.

     6.2 Watson represents and warrants that its production procedures
(including the Production Procedures) will conform to the applicable
requirements of the Regulatory Standards. Watson warrants that each shipment of
the Final Product will conform to the Final Specifications and will be made,
stored and controlled by Watson in accordance with applicable Regulatory
Standards and the process and procedures contained in the Production Procedures
and the applicable Technical Agreement.

     6.3 Watson represents and warrants that the Final Product shall (i) be free
from defects in material and workmanship, (ii) not be adulterated or misbranded
and (iii) be sold free and clear of any liens, claims or encumbrances, and that
the labels obtained by Watson will conform to the label copy provided and
approved by Customer for the country specified on Customer's purchase order for
such Final Product.

     6.4 Watson has previously furnished Customer with a copy of its Production
Procedures and has identified to Customer the equipment to be used to produce
the Final Product. Watson shall not (i) modify the Production Procedures, (ii)
modify any method of manufacturing or testing the API or the Final Product,
(iii) change or materially relocate any equipment used in the production of
Final Product, or (iv) change a vendor for any components or raw materials used
in the Final Product, in each case, without obtaining Customer's prior written
consent, which consent shall not be unreasonably withheld or delayed.


                                       5

<PAGE>   6

     6.5 Customer or its representative will have the right to inspect the
Production Facility and Watson's records relating to manufacturing, packaging,
and testing of the Final Product on a yearly basis, or more frequently for cause
as set forth below. For purposes of this Section, "for cause" shall mean:
failure of Final Product to meet Final Specifications upon receipt of Final
Product by Customer; issuance of adverse audit or inspection observations from
the FDA or another similar regulatory authority related to the Production
Facility or Final Product; and lack of follow-up on outstanding actions items
from previous audits or inspections related to the Production Facility or Final
Product. "Adverse" shall mean (i) a significant FDA 483 observation, or its
equivalent from another similar regulatory authority, likely to adversely affect
the quality of Final Product, (ii) receipt of an FDA warning letter, or its
equivalent, from another similar regulatory authority, addressing the Final
Product or key quality assurance systems at the Production Facility, or (iii) a
finding by an investigator of an absence of a key quality assurance system
likely to adversely affect the quality of Final Product. Such inspections shall
occur during Watson's normal hours of operation and upon reasonable notice.
Watson shall take appropriate actions to adopt reasonable suggestions of
Customer to correct any deficiencies identified by such inspection or audit. To
supplement this provision, and in accordance with the frequency provisions set
for herein, Customer also may arrange, at its cost and expense, to have a
Customer employee or other representative located on the premises of the
Production Facility participate in the monitoring of Final Product production,
testing and packaging under this Agreement. All information acquired pursuant to
the provisions of this paragraph are subject to the requirements of
confidentiality as contained in the Confidentiality Agreement.

     6.6 Watson will notify Customer of any product quality complaints
pertaining to Final Product within ten business days following the receipt of
such complaint. Watson will cooperate with Customer and any governmental
authority in evaluating any complaint, claim, or adverse drug reaction report
related to the production of Final Product. All serious product quality
complaints (for example, foreign tablet/capsule, missing or incorrect labeling)
shall be preliminarily assessed within 48 hours of receipt of such complaint.
All product quality complaint investigations that do not require laboratory
analysis shall be completed within 30 days following the receipt of such
complaint. All product quality complaint investigations that require laboratory
analysis shall be completed within 45 days following the later of the receipt of
such complaint or the receipt of the applicable product sample. Watson shall
take such other steps as may be appropriate to resolve any identified problems.

     6.7 As may be further discussed in the Technical Agreements, Watson will
provide Customer with timely notification of all deviations, notes to file, and
other deficiencies that may impact the quality of the Final Product, regarding
testing of the API and Final Product and manufacture, or packaging of the Final
Product or the Production Facility.

     6.8 DISCLAIMER. EXCEPT AS EXPRESSLY PROVIDED IN THIS AGREEMENT, WATSON
MAKES NO OTHER REPRESENTATION OR WARRANTY, EXPRESS OR IMPLIED, AND WATSON HEREBY
EXPRESSLY DISCLAIMS ANY AND ALL IMPLIED OR STATUTORY WARRANTIES, INCLUDING
WITHOUT LIMITATION, WARRANTIES OF MERCHANTABILITY, INFRINGEMENT, OR FITNESS FOR
A PARTICULAR PURPOSE.

7.0 RECORDS, REGULATORY MATTERS.


                                       6
<PAGE>   7

     7.1 Except as otherwise provided in this Agreement, Watson will maintain
complete and accurate records relating to the Final Product and the manufacture,
packaging, and testing thereof for the period required by applicable Regulatory
Standards, and Watson shall provide copies thereof to Customer upon Customer's
request. Without limiting the generality of the foregoing, prior to release of
each batch, Watson shall perform quality assurance and control tests on each lot
of Final Product manufactured before delivery and shall prepare and deliver to
Customer a written report of the results of such tests, with each report setting
forth for each lot delivered the items tested, specifications and results in a
certificate of analysis containing the type of information which is required by
the applicable Regulatory Standards.

     7.2 Watson will supply for each batch of Final Product, including each
pilot batch, complete batch production and control records.

     7.3 Watson shall ensure that the Production Facility and the equipment and
personnel used to manufacture Final Product are now, and at the time each batch
of Final Product is produced shall be, maintained in a professional and
workmanlike manner, consistent with generally accepted industry standards.
Watson represents and warrants that (i) the Production Facility is in compliance
with all applicable material requirements of the Regulatory Standards, and (ii)
there are no pending or uncorrected citations or adverse conditions noted in any
inspection of the Production Facility which would cause the Final Product to be
misbranded or adulterated.

     7.4 In addition to any authorizations required under Section 7.3, Watson
has obtained all other licenses, authorizations and approvals required by any
federal, state or local governmental authority for the production of the Final
Product, and the Production Facility complies with all laws, rules and
regulations applicable to it.

     7.5 Watson shall promptly notify Customer if the FDA or other regulatory
authority visits or makes written or oral inquiries about the Production
Facility or Watson's procedures, to the extent such inquiries relate to the
production, testing, packaging, storage or handling of API or Final Product.
Watson shall furnish Customer, within thirty (30) days after receipt, a copy of
any report or correspondence issued by the governmental authority in connection
with such visit or inquiry, purged only of confidential information that is
unrelated to the API or Final Product or the activities under this Agreement.

     7.6 In the event that either Watson or Customer determine that the Final
Product should be recalled, the parties shall discuss the issues and take all
appropriate corrective actions, and shall cooperate in the investigations
surrounding the situation. Only Customer shall have the right to order a recall,
provided however, that if Watson believes such a recall is necessary and
Customer declines to do so, Watson may contact the relevant regulatory agencies
regarding such matter.

8.0 TERM.

     8.1 This Agreement shall be effective as of the Effective Date and shall
continue through [*], subject to earlier termination in accordance with the
terms hereof. Thereafter it will be automatically renewed for successive [*]
unless terminated by either party by written notice given no less than [*]
before the end of the term or any renewal term hereof.


* Confidential information omitted and filed separately with the Commission.



                                       7


<PAGE>   8

9.0 MINIMUM PURCHASE REQUIREMENTS, FORECASTS, ORDERS AND DELIVERY.

     9.1 Customer shall order and purchase, for delivery in each of [*], at
least [*] of Final Product (with each such batch nominally being composed of
either [*]). On or before September 30, 2001, and September 30, 2002, Customer
may provide Watson with a non-binding annual forecast for Final Product to be
delivered in [*] respectively, not to exceed [*]. Notwithstanding the
non-binding nature of such forecasts, Customer shall be obligated to order and
purchase [*] (rounded up to the nearest whole number) and Watson shall be
obligated to manufacture and supply [*] (rounded up to the nearest whole
number). In no event shall Watson be obligated to manufacture and supply in [*]
more than [*] Customer ordered for delivery in [*] (rounded up to the nearest
whole number). If Customer does not supply such forecast(s), Customer shall
order and purchase, for delivery in [*], as the case may be, at least [*] of
Final Product. In addition, to assist Watson in scheduling production for the
manufacture of the Final Product, Customer shall provide to Watson, quarterly, a
twelve (12) month rolling forecast of its requirements for a Final Product. The
first forecast shall be provided by Customer to Watson approximately six months
prior to the anticipated market launch of the Final Product in each respective
country in the Territory, as reasonably estimated by the parties, and thereafter
shall be provided to Watson on or before the 20th day of the second month of
each successive quarterly period (to forecast the requirements for the next
twelve (12) succeeding calendar months). All such quarterly forecasts shall be
non-binding. Customer shall issue firm purchase orders to Watson. Watson shall
be required to accept such purchase orders to the extent they are in compliance
with this Agreement and do not exceed [*]. Each such purchase order shall be in
writing in a form reasonably acceptable to Watson, and shall specify the
quantity ordered, the price therefor, the place of delivery and the required
delivery date therefor, which shall be not less than [*] after the specified
date of such purchase order. The timely performance of Watson's obligations
hereunder shall be subject to timely receipt of acceptable API by Watson. For
purposes of determining compliance with this Section 9.1, Watson shall be deemed
to have finally delivered Final Product when it is packaged and ready to ship,
notwithstanding any delay in shipping while awaiting formal release of Final
Product by Customer. All purchase orders shall be for minimum batch size
quantities reasonably agreed to by the parties.

     9.2 Watson will arrange for shipping and/or transportation for the Final
Product from Watson's Production Facility; provided, however, that Customer may
provide Watson with specific shipping instructions and direct the use of a
specific carrier, and [*].

10.0 GENERAL INDEMNITIES.

     10.1 Watson will indemnify and hold Customer harmless from any and all
liability, damage, loss, cost, or expense (including reasonable attorney's fees)
relating to third party (which shall exclude Customer's members and affiliates)
claims which arise from (i) Watson's breach of



* Confidential information omitted and filed separately with the Commission.

                                       8

<PAGE>   9

any of its agreements, representations, or warranties contained herein, (ii)
Watson's negligence or other wrongful conduct as determined by a court of
competent jurisdiction or (iii) a claim that the Production Procedures utilized
by Watson (except for those provided to Watson by Customer) to manufacture the
Final Product infringe a United States patent or any other proprietary rights of
any third party. Upon learning of any such third party claim or suit against it,
Customer shall immediately notify Watson.

     10.2 Customer will indemnify and hold Watson harmless from any and all
liability, damage, loss, cost, or expense (including reasonable attorney's fees)
relating to third party claims (which shall exclude Watson's affiliates) which
arise from the distribution, marketing, sale or use of the Final Product except
to the extent such liability, damage, loss, cost or expense arises from (i)
Watson's breach of any of its agreements, representations, or warranties
contained herein, (ii) Watson's negligence or Watson's other wrongful conduct as
determined by a court of competent jurisdiction or (iii) a claim that the
Production Procedures utilized by Watson (except for those provided to Watson by
Customer) to manufacture the Final Product infringe a United States patent or
any other proprietary rights of any third party. Upon learning of any such claim
or suit against it, Watson shall immediately notify Customer.

     10.3 The parties will cooperate with each other in the defense of any claim
or action.

     10.4 No indemnifying party hereunder will be liable for any costs
associated with the settlement of any claim or action brought against it or the
other party unless it has received prior notice of the settlement negotiations
and has agreed to the settlement in writing.

11.0 LIMITATION OF LIABILITY.

     11.1 EXCEPT AS MAY BE REQUIRED UNDER ARTICLE 10, NEITHER PARTY SHALL BE
LIABLE TO THE OTHER FOR ANY INDIRECT, INCIDENTAL, CONSEQUENTIAL, SPECIAL OR
EXEMPLARY DAMAGES, INCLUDING BUT NOT LIMITED TO LOST PROFITS, ARISING FROM OR
RELATING TO ANY BREACH OF, OR ACTIONS UNDERTAKEN IN CONNECTION WITH THIS
AGREEMENT, OR THE TERMINATION THEREOF, REGARDLESS OF ANY NOTICE OF THE
POSSIBILITY OF SUCH DAMAGES.

12.0 INSURANCE.

     12.1 Each of Watson and Customer (or Customer's Members for the benefit of
Customer) shall carry product liability insurance in an amount at least equal to
[*] with an insurance carrier reasonably acceptable to the other party, such
insurance to be in place at times reasonably acceptable to the parties, but not
later than the date of the first commercial sale of the Final Product. Each
party shall promptly furnish the other evidence of the maintenance of the
insurance required hereunder and shall name the other as an "additional insured"
under such insurance policy. Each party's coverage shall (i) include broad form
vendor coverage and such other provisions as are typical in the industry and
(ii) name the other party as an additional insured thereunder. Each party agrees
that the insurance policies maintained by the other party on the date hereof
satisfy the requirements of this Section 12.1.

13.0 FINAL PRODUCT ACCEPTANCE.


* Confidential information omitted and filed separately with the Commission.


                                       9


<PAGE>   10

     13.1 Watson shall, subject to the limitations in Section 9.1, manufacture
the Final Product ordered by Customer and make it available for pick up in
accordance with all applicable laws, rules and regulations including, without
limitation, the Final Specifications and all other applicable requirements of
the FDA and other governmental authorities having jurisdiction. All Final
Product shipped to Customer shall be accompanied by quality control certificates
of analysis signed by a duly authorized laboratory official of Watson confirming
that each batch of Final Product covered by such certificate meets its release
Final Specifications and shall be deemed accepted by it unless Customer, acting
reasonably and in good faith, shall give written notice of rejection (hereafter
referred to as a "Rejection Notice") to Watson within 35 days after pick up of
the Final Product by, on behalf of, or for the account of Customer at Watson's
facility.

     13.2 The Rejection Notice shall state in reasonable detail (sufficient to
enable Watson to identify the nature of the alleged problem and the tests or
studies to be conducted by or on its behalf to confirm or dispute same) the
reason why the Final Product is not acceptable to Customer (the "Rejection
Basis"). Any Rejection Notice shall be accompanied by copies of all written
reports relating to tests, studies or investigations performed to that date by
or for Customer on the Final Product batch rejected.

     13.3 Upon receipt of such Rejection Notice, Watson may require Customer to
return the rejected Final Product or samples thereof to Watson for further
testing, in which event such Final Product or samples thereof as the case may
be, shall be returned by Customer to Watson. If it is later determined by the
parties or by an independent laboratory or consultant that Customer was not
justified in rejecting the Final Product or that Customer was the cause of or
was responsible for the Rejection Basis, Customer shall reimburse Watson for the
costs of the return, as well as any other costs or expenses incurred by Watson
as a result of the rejection or return.

     13.4 If any order of Final Product is rejected by Customer, Customer's duty
to pay all amounts payable to Watson in respect of the rejected Final Product
shall be suspended until such time as it is determined (i) by an independent
laboratory or consultant that the Final Products in question should not have
been rejected by Customer, i.e., Final Product meets the applicable provisions
of the Final Specifications, has been manufactured in accordance with
representations and warranties provided herein, is labeled as required by the
Customer and is provided in quantities specified in a purchase order, or (ii) by
the parties or by any arbitration conducted pursuant hereto or by a final order
of a court of competent jurisdiction (which is not subject to further appeal)
that any act or omission of, on behalf of or for which Customer is responsible
was the cause of the problem that was the basis for the rejection. If only a
portion of an order is rejected, only the duty to pay the amount allocable to
such portion shall be suspended.

     13.5 Customer's test results or basis for rejection shall be conclusive
unless Watson notifies Customer, within 35 days of receipt by Watson of the
rejected Final Products or samples that it disagrees with such test results or
its responsibility for the problem in question. In the event of such notice by
Watson, representative samples of the batch of Final Products in question shall
be submitted to a mutually acceptable independent laboratory or consultant (if
not a laboratory analysis issue) for analysis or review, the costs of which
shall be paid by the party that is determined by the independent laboratory or
consultant to have been incorrect in its determination of whether the Final
Product should be rejected.


                                       10

<PAGE>   11


     13.6 In the event any Final Product is appropriately rejected by Customer,
Watson shall replace such Final Product with conforming goods as soon as
possible, but in any event within [*] weeks following its receipt of the
Rejection Notice, and shall be fully responsible for all costs associated with
replacing such Final Product, including the cost of the API required to replace
the Final Product or, if requested by Customer, shall provide a credit to
Customer for the amount, if any, previously paid by Customer to Watson on
account of the Final Product in question and for the full cost of replacing the
API utilized in the manufacture of the Final Product in question, including any
wasted API. The credit shall be provided by Watson to Customer immediately
following the expiration of the period during which Watson may dispute a
Rejection Notice as contemplated above (unless the Rejection Notice is disputed
by Watson, in which event such credit shall be given only if the dispute is
resolved in favor of Customer). Replacement Final Products, as aforesaid, shall
be delivered to Customer at no cost to Customer if Customer has already paid for
the rejected Final Products and not received a credit therefor, as aforesaid.
All delivery costs, including insurance, incident to the return of Final
Products to Watson and delivery of the replacement Final Products to Customer's
order shall be paid by Watson, unless the rejection is determined not to have
been appropriately rejected, in which case Customer shall reimburse Watson for
the costs of the return, as well as any other costs or expenses incurred by
Watson as a result of the rejection or return. [*].

14.0 FORCE MAJEURE.

     14.1 Neither Customer nor Watson shall be in default in the performance of
their obligations hereunder to the extent that such performance is delayed or
prevented by an act of God, weather conditions, strikes, lockouts, inability to
procure labor, materials, or fuels due to shortages, fires, riots, interference
by civil or military authorities, or acts of war (declared or undeclared), or
any other cause which is beyond the reasonable control of either party; provided
however, that should Watson experience a Force Majeure event which results in
its inability to perform under this Agreement, Customer's minimum purchase
obligations set forth in Section 2.2 shall be waived for the period during which
the Force Majeure event continues and the annual minimum purchase obligation
shall be adjusted accordingly. Should Watson be unable to perform hereunder due
to a Force Majeure event that continues for more than [*], Customer shall be
entitled to terminate this Agreement immediately thereafter.

15.0 TERMINATION.

     15.1 If either party hereto commits a material breach of any of its
obligations hereunder, the non-breaching party may, at its option, terminate
this Agreement by giving the other party at least sixty (60) days prior written
notice of its intent to terminate this Agreement, which notice shall specify the
breach and the termination date. Unless the breaching party cures the breach
prior to the termination date (or such longer period not to exceed an additional
sixty (60) days after the end of the aforementioned 60-day period reasonably
necessary to cure such breach, provided that the breaching party is making
diligent efforts to cure such breach), the Agreement shall terminate.

     15.2 Customer may terminate this Agreement upon written notice to Watson
effective immediately (i) upon the occurrence of the conditions specified in
either Section 2.4 or 14.1, provided however, that any such termination must be
made within forty-five (45) days of Customer's receipt of information or facts
giving rise to such right and (ii) if Watson shall continually deliver


* Confidential information omitted and filed separately with the Commission.

                                       11
<PAGE>   12

Final Product that is appropriately rejected in accordance with the terms of
Article 13. For purposes of this Section 15.2, "continually" shall mean more
than [*].

     15.3 Notwithstanding the terms of Section 15.1, (i) if Customer fails to
pay any sums owed hereunder within five (5) days after Watson has notified
Customer that such sums are past due, Watson may terminate this Agreement
immediately, or (ii) if either party should become insolvent or seek relief
under any bankruptcy, debtor relief, or similar law or if any proceeding against
either party under any such law remains in effect for a period of thirty (30)
consecutive days, the other party may terminate this Agreement immediately.

     15.4 Any termination of the Agreement shall not release the parties from
any liabilities and obligations accrued as of the date thereof.

     15.5 In the event of any termination of this Agreement, Watson shall, in a
timely manner, finalize the manufacture of any Final Product for which
manufacturing was initiated prior to termination, and shall make such Final
Product available for delivery to Customer in accordance with the terms and
conditions of this Agreement. Customer shall purchase such Final Product from
Watson in accordance with the terms of this Agreement, including but not limited
to, Article 13 hereof. In addition, in the event of termination of this
Agreement, Watson shall return to Customer (in such time frame as Customer shall
request, which shall not exceed 60 days following the effective date of
termination) any API with respect to which manufacturing has not been initiated
prior to termination. If the Agreement is terminated by Customer pursuant to
Sections 15.1 or 15.2, then such API shall be returned to Customer [*]. For all
other terminations, the API shall be returned to Customer [*]. For any
termination other than a termination by Customer pursuant to Section 15.1,
Customer agrees to purchase, accept delivery of, and pay for unused packaging
and labeling and raw materials for the Final Product which are in Watson's
inventory or on order by Watson, to the extent not usable in Watson's business,
on the effective date of such termination. Notwithstanding the above, in no
event shall Customer be obligated to purchase Final Product, unused packaging,
labeling or other materials consisting of more than [*] based on the average
monthly product movement for the immediately preceding [*] period.

     15.6 Sections 10.0, 11.0, 15.4, 15.5 and this 15.6 and any other provisions
required to interpret and enforce the parties' rights and obligations under this
Agreement shall survive the termination of this Agreement to the extent required
for the full observation and performance of this Agreement by the parties in
accordance with its terms.

16.0 NON-WAIVER OF RIGHTS.

     16.1 Failure by Watson or Customer to enforce the terms and conditions of
the Agreement shall not affect or impair such terms or conditions, or the right
of Watson or Customer to avail itself of such remedies as it may have for any
breach of such terms or conditions under the provisions of this Agreement, in
equity or at law.

17.0 NOTICES.


* Confidential information omitted and filed separately with the Commission.

                                       12

<PAGE>   13


     17.1 Any notice given under this Agreement shall be deemed adequate if made
by facsimile (with confirmation of transmission), and certified mail or
registered mail, return receipt requested, postage prepaid, or by reputable
overnight courier (with evidence of delivery), and addressed as follows:

TO WATSON:                 WATSON LABORATORIES, INC. - NEW YORK
                           33 Ralph Avenue
                           Copiague, New York  11726-0030
                           Attention:       General Manager
                           Telephone Number: 631-842-8383
                           Facsimile Number: 631-842-8630

                                       And

                           WATSON PHARMACEUTICALS, INC.
                           311 Bonnie Circle
                           Corona, California  92880-2882
                           Attention:       Legal Department
                           Telephone Number: 909-270-1400
                           Facsimile Number: 909-279-8094




                                       13
<PAGE>   14


TO CUSTOMER:               RENAGEL  LLC.
                           c/o GelTex Pharmaceuticals, Inc.
                           153 Second Avenue
                           Waltham, Massachusetts  02451
                           Attention:  Vice President, Manufacturing
                           Telephone Number: 781-290-5888
                           Facsimile Number: 781-290-5890

     or to such other address as either of the parties shall designate by notice
given as herein required.

18.0 AMENDMENTS AND WAIVER.

     18.1 This Agreement cannot be amended in any respect except in writing duly
executed by both parties. No waiver of compliance with any provisions or
conditions of this Agreement and no approvals provided for in this Agreement
shall be effective unless evidenced by a written instrument executed by the
party waiving or approving, as applicable.

19.0 ASSIGNMENT.

     19.1 Neither party hereto shall assign this Agreement or any part thereof
or any interest herein without the written approval of the other party hereto;
however, either party may assign its rights and obligations under the Agreement
to any transferee or successor of the business to which this Agreement relates.

20.0 GOVERNING LAW.

     20.1 This Agreement shall be governed by the law of the State of New York,
without respect to conflict of law principles.

21.0 ENTIRE AGREEMENT.

     21.1 This writing, the Technical Agreements and the Confidentiality
Agreement constitute the entire understanding between the parties and shall
supersede any prior agreements between them. Each party acknowledges that there
are no other understandings, which relate to the matters covered herein, in the
Technical Agreements or in such Confidentiality Agreement or which are
inconsistent with any provisions of the Agreement. Should the terms of any
purchase order or invoice contemplated hereunder conflict with or add to the
terms of this Agreement, the terms of such purchase order or invoice shall be of
no force or effect and this Agreement shall control.

22.0 PARTIES INDEPENDENT.

     22.1 In making and performing this Agreement, the parties act and shall act
at all times as independent entities and nothing contained in this Agreement
shall be construed or implied to create an agency, partnership or employer and
employee relationship between Watson and Customer. Except as specifically
provided herein, at no time shall either party make commitments or incur any
charges or expenses for or in the name of the other party.


                                       14
<PAGE>   15

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement in
duplicate as of on the date and year first written above.

                                  WATSON LABORATORIES, INC. - NEW YORK

                                  By: /s/ David Buchen
                                     -----------------------------------------
                                  Title:
                                        --------------------------------------
                                  [Printed Name]


                                  RENAGEL LLC

                                  By: GELTEX PHARMACEUTICALS, INC.,
                                  Its Member

                                  By:  /s/ Mark Skaletsky
                                     -----------------------------------------
                                  Name:
                                       ---------------------------------------
                                  Title:
                                        --------------------------------------
                                        [Printed Name]


                                  RENAGEL LLC

                                  By: GENZYME CORPORATION
                                  Its Member

                                  By:  /s/ G. Jan van Heek
                                     -----------------------------------------
                                  Name:
                                       ---------------------------------------
                                  Title:
                                        --------------------------------------
                                        [Printed Name]

     GELTEX PHARMACEUTICALS, INC. and GENZYME CORPORATION hereby jointly and
severally guarantee the performance by RenaGel LLC of its obligations hereunder,
including obligations set forth in any related agreements, including but not
limited to, all Technical Agreements.

                                   GELTEX PHARMACEUTICALS, INC.

                                   By:  /s/ Mark Skaletsky
                                       ---------------------------------------
                                   Name:
                                        --------------------------------------
                                   Title:
                                         -------------------------------------


                                   GENZYME CORPORATION

                                   By: /s/ G. Jan van Heek
                                      ----------------------------------------
                                   Name:
                                        --------------------------------------
                                   Title:
                                         -------------------------------------

                                       15