<PAGE>   1
                                                                    EXHIBIT 10.4

                                            The deleted portions of this Exhibit
                                                contain confidential information
                                         and have been filed separately with the
                                              Securities and Exchange Commission

                     Amendment #2 dated March 27, 2000 to Agreement No. 19984813

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

Agreement No. 19984813, between Amgen Inc. ("Amgen") and National Medical Care,
Inc., including any prior amendments thereto, shall be amended, and for the
period commencing 1/1/2000 shall be restated in its entirety to read as stated
below.

This Agreement ("Agreement"), between Amgen Inc. ("Amgen") and National Medical
Care, Inc., including its subsidiaries and affiliates that are at least fifty
and one-tenth percent (50.10%) owned by National Medical Care, Inc. listed on
Appendix B, (collectively, "NMC"), sets forth the terms and conditions for the
purchase of EPOGEN(R) (Epoetin alfa) by NMC.

1.   TERM OF AGREEMENT. The "Term" of this Agreement shall be defined as January
     1, 2000 ("Commencement Date") through December 31, 2000 ("Termination
     Date").

2.   QUALIFIED PURCHASES. All terms contained herein apply only to purchases
     made hereunder, as confirmed by Amgen ("Qualified Purchases"), by NMC and,
     subject to the terms of Section 13, to all affiliates opened, acquired, or
     managed by NMC during the Term, for so long as such affiliates remain at
     least fifty and one-tenth percent (50.10%) owned or managed by National
     Medical Care, Inc. ("Affiliates"), through wholesalers chosen by NMC and
     authorized by Amgen to participate in the program ("Authorized
     Wholesalers") or directly from Amgen. In addition, and also subject to the
     terms of Section 13, Affiliates of Renaissance Health Care, Clinic, Inc.,
     Optimal Renal Care, L.L.C., Integrated Renal Care of the Pacific, and/or
     any joint venture of NMC in which NMC holds at least a fifty and one-tenth
     percent (50.10%) ownership interest, will also be eligible to participate,
     although not required to purchase. Amgen agrees to reasonably approve
     Authorized Wholesalers requested by NMC. The option to purchase on a direct
     basis from Amgen is subject to receipt and approval, not to be unreasonably
     withheld, of an "Application for Direct Ship Account".

3.   PRICING. See Appendix A.

4.   PAYMENT TERMS. The terms and conditions of this Agreement shall apply
     whether NMC and/or Affiliates purchase EPOGEN(R) through an Authorized
     Wholesaler or from Amgen directly.

5.   PRODUCT ACQUISITION COSTS. As long as NMC and Affiliates are the [DELETED],
     non-governmental, freestanding dialysis center (including home dialysis
     affiliates) purchaser of EPOGEN(R) in the United States, Puerto Rico and
     Guam during the Term, on an annual, calendar year basis, Amgen commits that
     this Agreement provides NMC and Affiliates with [DELETED] for EPOGEN(R)
     available to any freestanding dialysis center purchaser in the United
     States and Puerto Rico with comparable growth and percentage of patients
     with hematocrit levels greater than or equal to [DELETED]. If NMC and
     Affiliates are not the [DELETED] non-governmental, freestanding dialysis
     center purchaser of EPOGEN(R) in the United States, Puerto Rico and Guam
     during the Term, on a calendar year basis, Amgen may provide [DELETED] for
     EPOGEN(R) to [DELETED] non-governmental, freestanding dialysis center
     purchaser(s). Qualification as a freestanding dialysis center shall be
     determined by Amgen in its reasonable discretion, in accordance with
     Amgen's customer classification policies, which generally classify
     freestanding dialysis centers as independent, exclusive providers of
     dialysis services, which (a) may not obtain EPOGEN(R) from or through a
     hospital, or (b) are not otherwise affiliated with a hospital, nursing
     home, or integrated health care system. This commitment excludes [DELETED]
     available to any governmental entities, or [DELETED] mandated by Title 38
     (Veterans' Benefits) or Title 42 (The Public Health and Welfare) of the
     United States Code, or any other federal or state health care program.
     Amgen's agreement to make this commitment is contingent upon its ability to
     comply with all federal, state, local and military laws, statutes and
     regulations.

6.   MINIMUM PRODUCT PURCHASE AGREEMENT. NMC and Affiliates agree to purchase a
     minimum of [DELETED] of EPOGEN(R) from Amgen hereunder during each
     consecutive calendar quarter during the Term.

<PAGE>   2
7.   DISCOUNT. Amgen will pay discounts and incentives in accordance with the
     schedule and terms set forth in Appendix A attached hereto.


8.   PAYMENT OF DISCOUNTS. Any discount (hereinafter defined as including a
     discount at time of purchase, rebate, incentive or other concession
     impacting the pricing of a product) earned hereunder shall be calculated in
     accordance with this Agreement, based on Qualified Purchases, using
     [DELETED] as the calculation price, and shall be paid in the form of a wire
     transfer to NMC's corporate headquarters, except as otherwise provided. NMC
     and Affiliates shall make available to Amgen any records concerning NMC's
     and Affiliates' purchase amounts that Amgen or its auditors may reasonably
     request. Amgen shall make available to NMC any records concerning NMC's and
     Affiliates' purchase amounts that NMC or its auditors may reasonably
     request. [DELETED] Amgen will use its best efforts to make any discount
     (excluding discounts at time of purchase) pursuant to this Agreement
     available in accordance with the terms referenced in Appendix A.
     Availability of discounts is contingent upon Amgen receiving all relevant
     purchase data from all Authorized Wholesalers designated by NMC, in a form
     reasonably acceptable to Amgen, detailing NMC's and Affiliates' Qualified
     Purchases of EPOGEN(R) for the relevant period, along with any other data
     required by the terms of Appendix A. In the event of any purchases directly
     from Amgen, all such purchase data shall be included in the calculation of
     all discounts. In no event shall Amgen pay any discount on EPOGEN(R)
     distributed by NMC or Affiliates to non-Affiliates of NMC (see Section 2
     for definition of Affiliates). Subject to the section entitled "Breach of
     Agreement", in the event that Amgen is notified in writing that National
     Medical Care, Inc. and/or any of its subsidiaries or Affiliates (the
     "Acquiree") is acquired by another entity or a change of control otherwise
     occurs with respect to the Acquiree, any discount which may have been
     earned hereunder prior to the effective date of the acquisition shall
     vest, and shall be paid in the form of a wire transfer to NMC's corporate
     headquarters subject to the conditions described herein.

9.   TREATMENT OF DISCOUNTS. The parties agree that they will account for any
     discount earned hereunder in a way that complies with all applicable
     federal, state, and local laws and regulations, including without
     limitation, Section 1128B(b) of the Social Security Act and its
     implementing regulations, and if required by such statutes or regulations
     (a) claim the benefit of such discount received, in whatever form, in the
     fiscal year in which such discount was earned or the year after, (b) fully
     and accurately report the value of such discount in any cost reports filed
     under Title XVIII or Title XIX of the Social Security Act, or a state
     health care program, and (c) provide, upon request by the U.S. Department
     of Health and Human Services or a state agency or any other federally
     funded state health care program, the information furnished by Amgen
     concerning the amount or value of such discount. NMC agrees that it will
     advise all Affiliates, in writing, of any discount received by NMC's
     corporate headquarters hereunder with respect to purchases made by such
     Affiliates and that NMC will advise said Affiliates as to their requirement
     to account for any such discount in accordance with the above stated
     requirements.

10.  COMMITMENT TO PURCHASE. NMC and Affiliates agrees to purchase EPOGEN(R) for
     all of its dialysis use requirements in the United States, Puerto Rico and
     Guam for recombinant human erythropoietin. Amgen agrees to make such
     EPOGEN(R) available to NMC and Affiliates through its Authorized
     Wholesalers or directly from Amgen. In addition to other remedies available
     to NMC and Affiliates, NMC and Affiliates may purchase another brand of
     recombinant human erythropoietin for its dialysis use requirements in the
     United States, Puerto Rico and Guam if, and only if, NMC and Affiliates
     have informed Amgen, in writing, that NMC and Affiliates are unable to
     acquire sufficient amounts of EPOGEN(R) to meet NMC's and Affiliates'
     reasonable dialysis use requirements, and Amgen by itself, or through its
     Authorized Wholesalers, is actually unable to supply NMC and Affiliates
     with their reasonable dialysis use requirements of EPOGEN(R) within the
     time period reasonably required by NMC and Affiliates, which, in no event
     will be less than five (5) business days after Amgen's receipt of NMC's and
     Affiliates' written notice. If the preceding requirements are met, NMC and
     Affiliates will only be allowed to purchase another brand of recombinant
     human erythropoietin for the time period, and to the extent, that Amgen is
     unable to provide NMC and Affiliates with EPOGEN(R) to meet NMC's and
     Affiliates' reasonable dialysis use requirements.

11.  OWN USE. NMC hereby certifies that EPOGEN(R) purchased hereunder will be
     for the "own use" by NMC and the Affiliates of NMC.

12.  AUTHORIZED WHOLESALERS. A complete list of NMC's and Affiliates' current
     Authorized Wholesalers, through whom NMC and Affiliates may purchase
     EPOGEN(R) hereunder is attached as Appendix C. NMC and Affiliates agrees to
     promptly

<PAGE>   3
     provide Amgen with any additions, deletions, or changes to the initial list
     of Authorized Wholesalers. Amgen requires no less than 30 days notice
     before the effective date of change for any addition or deletion of
     Authorized Wholesalers hereunder. Any proposed changes to the initial list
     of Authorized Wholesalers must be in writing and are subject to reasonable
     approval by Amgen.

13.  SUBSIDIARIES AND AFFILIATES. Within 30 days of execution of this Agreement,
     NMC shall provide a current listing of all Affiliates, and other entities,
     that will be participating in this Agreement, designating which Affiliates
     are owned and/or managed by NMC. Such listing will be incorporated into
     this Agreement as Appendix B. Only those entities listed on Appendix B will
     be eligible to participate in this Agreement. Any NMC managed Affiliate, or
     other entity with an existing contract, may participate in either their
     existing agreement with Amgen, or this Agreement, but not both. Each
     managed Affiliate or entity must declare under which single Amgen contract
     it will participate. Only Qualified Purchases under this Agreement will be
     used in the calculation of pricing, discounts or other incentives under
     this Agreement. NMC will notify Amgen of changes to Appendix B, and the
     effective date of change. Such effective date of change may not be earlier
     than the date the notice is received by Amgen. Any proposed change to
     Appendix B will be subject to the reasonable approval of Amgen based upon
     Amgen's then current legal and contractual requirements, and such proposed
     affiliate's classification as a freestanding dialysis center or a home
     dialysis support facility.

14.  BREACH OF AGREEMENT. Either party may terminate this Agreement for a
     material breach upon thirty (30) days advance written notice provided such
     breach remains uncured at the end of the thirty (30) day period.

15.  CONFIDENTIALITY. Both Amgen and NMC agree that this Agreement represents
     and contains confidential information which will not be disclosed to any
     third party, or otherwise made public, without prior written authorization
     of the other party, except where such disclosure is contemplated hereunder
     or required by law or court order. In the event NMC believes it is
     obligated to disclose any such information as required by law or court
     order, NMC will provide Amgen with prior written notice and an opportunity
     to seek a protective order and NMC shall furnish only that portion of the
     information that its counsel advises is required to be disclosed by law.

16.  WARRANTIES. Each party represents and warrants to the other that this
     Agreement (a) has been duly authorized, executed, and delivered by it, (b)
     constitutes a valid, legal, and binding agreement enforceable against it in
     accordance with the terms contained herein, and (c) does not conflict with
     or violate any of its other contractual obligations, expressed or implied,
     to which it is a party or by which it may be bound. NMC represents and
     warrants that it has the power to bind National Medical Care, Inc. and the
     subsidiaries and owned Affiliates listed on Appendix B to the terms
     contained herein. NMC shall cause each managed Affiliate to be bound by the
     terms and conditions of this Agreement through the execution of a joinder
     agreement executed between NMC and each such managed Affiliate.

17.  GOVERNING LAW. This Agreement will be governed by the laws of the State of
     Delaware and the parties submit to the jurisdiction of Delaware courts,
     both state and federal.

18.  NOTICES. Any notice or other communication required or permitted hereunder
     will be in writing and shall be deemed given or made when delivered in
     person or when received by the other party sent by U.S. Mail, return
     receipt requested, at the respective party's address set forth below or at
     such other address as the party shall have furnished to the other in
     accordance with this provision.

19.  COMPLIANCE WITH HEALTH CARE PRICING LEGISLATION AND STATUTES.
     Notwithstanding anything contained herein to the contrary, at any time
     following the enactment of any federal, state, or local law or regulation
     that materially reforms, modifies, alters, restricts, or otherwise affects
     the pricing of or reimbursement available for EPOGEN(R), either party may
     initiate good faith negotiations to modify this Agreement. If after
     forty-five (45) days the parties are unable to in good faith mutually agree
     to modifications to this Agreement, (a) either party may terminate this
     Agreement immediately, or (b) Amgen may exclude any owned or managed
     Affiliates from participating in this Agreement unless such owned or
     managed Affiliate(s) certifies in writing that they are, or will be, exempt
     from the provisions of such enacted law or

<PAGE>   4
     regulation. Additionally, in order to assure compliance with any existing
     federal, state or local statute, regulation or ordinance, Amgen reserves
     the right, in its reasonable discretion, to exclude any owned or managed
     Affiliates from the pricing, discount, and incentive provisions of this
     Agreement. In the event there is a future change in Medicare, Medicaid, or
     other federal or state statutes or regulations or in the interpretation
     thereof, which renders any of the material terms of this Agreement unlawful
     or unenforceable, this Agreement shall continue and shall be amended by the
     parties as a result of good faith negotiations as necessary to bring the
     Agreement into compliance with such statute and regulation.

20.  MISCELLANEOUS. No modification of this Agreement shall be effective unless
     made in writing and signed by a duly authorized representative of each
     party. This Agreement constitutes the entire agreement of the parties
     pertaining to the subject matter hereof and supersedes all prior written
     and oral agreements and understandings pertaining hereto including without
     limitation, any previous or existing contract or amendment for the purchase
     of EPOGEN(R). Neither party shall have the right to assign this Agreement
     to a third party without the prior written consent of the other party.
     Neither party shall be liable for delays in performance and nonperformance
     of this Agreement or any covenant contained herein caused by fire, flood,
     storm, earthquake or other act of God, war, rebellion, riot, failure of
     carriers to furnish transportation, strike, lockout or other labor
     disturbances, act of government authority, inability to obtain material or
     equipment, or any other cause of like or different nature beyond the
     control of such party. However, during any time of nonperformance by Amgen
     which involves NMC's and Affiliates' inability to obtain sufficient
     EPOGEN(R) to meet NMC's and Affiliates' reasonable dialysis use
     requirements the [DELETED] for such nonperformance, the [DELETED] and NMC
     and Affiliates may purchase EPOGEN(R) from another supplier. The parties
     shall execute and deliver all documents, provide all information, and take
     or refrain from taking action as may be necessary or appropriate to achieve
     the purposes of this Agreement. This Agreement may be executed in one or
     more counterparts, each of which is deemed to be an original but all of
     which taken together constitutes one and the same agreement. Amgen reserves
     the right to rescind this offer if the parties fail to execute this
     Agreement within thirty (30) days from the date of its offering.

Please retain one fully executed original for your records and return the other
fully executed original to Amgen.


THE PARTIES EXECUTED THIS AMENDMENT AS OF THE DATES SET FORTH BELOW.


AMGEN INC.                             NATIONAL MEDICAL CARE, INC.

Signature:     \s\ Eric Benevich      Signature:     \s\ Robert J. McGorty
Print Name:    Eric Benevich          Print Name:    Robert J. McGorty
Print Title:   Product Manager        Print Title:   Vice President of
                                                     Finance and Administration
Date:          3/29/00                Date:          3/29/00


<PAGE>   5


                APPENDIX A: DISCOUNT PRICING, SCHEDULE, AND TERMS
                -------------------------------------------------

1.   PRICING. NMC and Affiliates may purchase EPOGEN(R) directly from Amgen or
     through Authorized Wholesalers at a [DELETED]. Resulting prices do not
     include any wholesaler markup, service fees, or other charges.

2.   [DELETED] NMC and Affiliates agree to provide [DELETED] for the purposes of
     calculating [DELETED]. Amgen will accept the [DELETED] multiply each
     [DELETED] by [DELETED] and apply the converted results to [DELETED].
     [DELETED] Amgen will accept electronic data from the lab systems that
     service each owned or managed Affiliate. For NMC to qualify for the
     [DELETED] the following requirements must be met:

A.       REQUIREMENTS: In order to participate in the [DELETED] NMC and
         Affiliates must provide the following information for each dialysis
         patient to Amgen or to a data collection vendor specified by Amgen, on
         a [DELETED] basis, no later than [DELETED] after the end of [DELETED]:*

         i)       facility ID, [DELETED] [DELETED] for EPOGEN(R), [DELETED],
                  treatment date, [DELETED], [DELETED], [DELETED], [DELETED],
                  [DELETED], EPOGEN(R) dose (collectively the "Data"). Amgen may
                  utilize the Data for any purpose, and reserves the right to
                  audit all Data. Notwithstanding the foregoing, Amgen shall not
                  sell or re-sell any Data obtained pursuant to this Agreement.
                  Additionally, any use by Amgen of such Data shall be in a
                  format that does not identify NMC as the source of such Data,
                  unless NMC has consented to such use. Under no circumstances
                  should the Data include any patient identifiable information
                  including, without limitation, name, complete social security
                  number, address or birth date. The identity of the account
                  submitting the Data and any association with the Data will
                  remain confidential and will not be used in a manner that is
                  patient identifiable. The [DELETED] must be derived from
                  [DELETED] taken immediately before dialysis treatment using
                  any automated [DELETED] testing method (e.g [DELETED]) must be
                  reported to the [DELETED], and must be submitted in a format
                  acceptable to Amgen. Hand written reports are not acceptable;
                  electronic submission of the Data is preferred; and

         ii)      [DELETED] and

         iii)     a properly executed "Annual Certification Letter", a sample of
                  which is attached hereto as Exhibit #1, that will be provided
                  to NMC's corporate headquarters, unless otherwise requested,
                  after this Agreement is executed by both parties.

         *NOTWITHSTANDING THE REQUIREMENT TO SUBMIT DATA ON A [DELETED] BASIS
REFERENCED ABOVE, THE [DELETED] DATA ELEMENTS REFERENCED IN 2a ii) ABOVE SHALL
BE REQUIRED FOR THE [DELETED] WITHIN [DELETED] DAYS FOLLOWING THE END OF THE
[DELETED]. COMMENCING WITH THE [DELETED] OF [DELETED], THE DATA ELEMENTS SET
FORTH IN 2a ii) SHALL BE REQUIRED ON A [DELETED] BASIS AS SET FORTH IN THIS
SECTION 2A.

B.       CALCULATION: Assuming NMC and Affiliates have fulfilled all
         requirements as described in Section 2(a) above, NMC's [DELETED]
         payment will be calculated as follows: The "Average Patient [DELETED] "
         for each dialysis patient will be based upon the average of all
         [DELETED] gathered for each patient during each [DELETED] of the Term.
         The [DELETED] of all dialysis patients with Average Patient [DELETED]
         greater than or equal to [DELETED] will be determined by dividing the
         total number of dialysis patients with Average Patient [DELETED]
         greater than or equal to [DELETED] by the total number of dialysis
         patients treated by NMC and Affiliates. The [DELETED] will be
         calculated based on NMC's and Affiliates' overall performance in
         accordance with Amgen's discount calculation policies.


<PAGE>   6
          APPENDIX A: DISCOUNT PRICING, SCHEDULE, AND TERMS (CONTINUED)
          -------------------------------------------------------------

C.       PAYMENT: The [DELETED] will be calculated on a [DELETED] and paid to
         NMC's corporate headquarters, except as otherwise provided hereunder.
         Payment is contingent upon receipt by Amgen of the Annual Certification
         Letter (attached hereto as Exhibit 1) and all required Data for the
         corresponding [DELETED]. Data shall be submitted to Amgen [DELETED] and
         no later than [DELETED]. If Data is [DELETED], NMC will not qualify for
         the [DELETED] for that [DELETED]. [DELETED]. However, if Amgen
         determines that any Affiliate(s) is consistently not submitting the
         required Data, Amgen reserves the right in its reasonable discretion to
         exclude such Affiliate's Qualified Purchases of EPOGEN(R)from the
         calculation of the [DELETED] for any relevant [DELETED]. [DELETED]
         payments will be based on the Data received from the [DELETED], and
         will equal a percentage of NMC's and Affiliates' total Qualified
         Purchases of EPOGEN(R) during each relevant [DELETED] (exclusive of any
         Qualified Purchases of EPOGEN(R) made by NMC or any Affiliate not
         meeting the Data submission requirements described above) as governed
         by the [DELETED] schedules listed below. Amgen reserves the right to
         modify the [DELETED] if the EPOGEN(R) package insert language changes.
         [DELETED].





<PAGE>   7
          APPENDIX A: DISCOUNT PRICING, SCHEDULE, AND TERMS (CONTINUED)
          -------------------------------------------------------------

                    [DELETED] INCENTIVE [DELETED] SCHEDULES:

         [DELETED]

         [DELETED]

D.       VESTING: The [DELETED] will vest on the [DELETED] and be paid in
         accordance with the terms and conditions of Section 2 c) Payment above.
<PAGE>   8


          APPENDIX A: DISCOUNT PRICING, SCHEDULE, AND TERMS (CONTINUED)

3.       [DELETED]: NMC shall be eligible to receive a [DELETED] if certain data
         elements are transmitted to Amgen [DELETED]. The [DELETED] will be
         calculated as a percentage of Qualified Purchases of
         EPOGEN(R) attributable to NMC and all Affiliates during each [DELETED]
         In order to qualify for the [DELETED], the following [DELETED] must be
         submitted by NMC and all Affiliates in an [DELETED] format reasonably
         acceptable to Amgen[DELETED] Facility ID, [DELETED] [DELETED],
         [DELETED] for EPOGEN(R), [DELETED], treatment date, [DELETED],
         [DELETED], [DELETED], [DELETED], calculated [DELETED], EPOGEN(R) dose,
         [DELETED], and [DELETED]. Such [DELETED] must be submitted on a
         [DELETED] basis, and no later than [DELETED]. If such [DELETED] is
         received more than [DELETED], NMC will not qualify for the [DELETED]
         for that [DELETED]. [DELETED] However, if Amgen determines that any
         Affiliate(s) is consistently not submitting the required [DELETED]
         Amgen reserves the right in its sole discretion to exclude such
         Affiliate's Qualified Purchases of EPOGEN(R) from the calculation of
         the [DELETED] for any relevant [DELETED]. [DELETED]

4.       [DELETED] NMC may qualify for the [DELETED] as described below.

         A.    CALCULATION: NMC's [DELETED] will be calculated in accordance
               with the following formula and with each relevant [DELETED]
               schedule listed below:

                                [DELETED] = A X B

         where
                  A = [DELETED].
                  B = [DELETED]
                  C = [DELETED]
                  D = [DELETED]


<PAGE>   9


          APPENDIX A: DISCOUNT PRICING, SCHEDULE, AND TERMS (CONTINUED)
          -------------------------------------------------------------


                    [DELETED] INCENTIVE [DELETED] SCHEDULES:

                                    [DELETED]

         [DELETED]
         (C-D)/D                                             B
         -------                                             -
         [DELETED]

                                    [DELETED]

         [DELETED]
         (C-D)/D                                             B
         -------                                             -
         [DELETED]


                                    [DELETED]

         [DELETED]
         (C-D)/D                                             B
         -------                                             -
         [DELETED]


                                    [DELETED]

         [DELETED]
         (C-D)/D                                             B
         -------                                             -
         [DELETED]



<PAGE>   10


          APPENDIX A: DISCOUNT PRICING, SCHEDULE, AND TERMS (CONTINUED)
          -------------------------------------------------------------

For the purposes of calculating [DELETED], Amgen will incorporate purchases of
any newly created facility (but not facilities added through acquisition).
[DELETED]

B.   VESTING: NMC's [DELETED] will vest on the [DELETED], and will be paid in
     accordance with the terms and conditions described above.


5.   [DELETED]. NMC may qualify for the [DELETED] as described below.

A.   CALCULATION: NMC's [DELETED] will be calculated in accordance with the
     following formula and in accordance with the [DELETED] schedule listed
     below.

                                [DELETED] = A X B
         where
                A =  [DELETED].
                B =  [DELETED].
                C =  [DELETED].
                D =  [DELETED].

         [DELETED]
         (C-D)/D                                            B
         -------                                            -
         [DELETED]

B.   VESTING: NMC's [DELETED] will vest on the last day of the Term, and will be
     paid [DELETED] thereafter.


<PAGE>   11


               APPENDIX B: LIST OF NMC SUBSIDIARIES AND AFFILIATES
               ---------------------------------------------------


                                  SUBSIDIARIES:
                                  -------------

       Bio-Medical Applications Management Co., Inc. and its subsidiaries

                                   Erika, Inc.

                               Infusion Care, Inc.

                                 LifeChem, Inc.

                  National Medical Care HomeCare Division, Inc.

                         Renal Research Institute, Inc.

                            Spectra Renal Management

                                   AFFILIATES:
                                   -----------

                           See Contract List Attached


<PAGE>   12


                 APPENDIX C: LIST OF NMC AUTHORIZED WHOLESALERS
                 ----------------------------------------------

TO ENSURE YOU RECEIVE THE APPROPRIATE DISCOUNT, IT IS IMPORTANT THAT WE HAVE
YOUR CURRENT LIST OF AUTHORIZED WHOLESALERS. THE FOLLOWING LIST REPRESENTS THE
WHOLESALERS AMGEN CURRENTLY HAS ASSOCIATED WITH YOUR CONTRACT. PLEASE UPDATE THE
LIST BY ADDING OR DELETING WHOLESALERS AS NECESSARY.

Bergen Brunswig Corporation
4000 Metropolitan Drive
Orange, CA  92668

J.M. Blanco Inc.
Calle D - Lote No. 21
Guaynabo, PR 00965

Metro Medical Supply, Inc.
3332 Powell Avenue
Nashville, TN 37204

Bellco Drug Corporation
101 East Hoffman Avenue
Lindenhurst, NY 11757


<PAGE>   13


                                                                      EXHIBIT #1

                       SAMPLE ANNUAL CERTIFICATION LETTER
                       ----------------------------------



Month X, 199X

FSDC Legal Name
Street Address
City, ST  Zip

RE:  EPOGEN(R)(Epoetin alfa) Agreement No. 19984813

Dear ____________:

Thank you for your participation in the [DELETED] Incentive Program. In order
for us to enroll you, we require that a duly authorized representative of your
organization sign the certification below.

Upon receipt of this executed document, we will calculate the value of your
incentive. If we do not receive the executed certification, we cannot provide
you with this incentive.

If you have any questions regarding this letter please contact me at [DELETED].
Thank you for your assistance in returning this certification.

Sincerely,



[DELETED]
Outcomes Incentive Analyst


CERTIFICATION:

On behalf of FSDC Legal Name and all eligible Affiliates participating in the
[DELETED] Incentive Program under Agreement No. 19984813, the undersigned hereby
certifies that the [DELETED] data submitted for each eligible Affiliate includes
the required [DELETED] results from all dialysis patients of such Affiliate, and
does not include [DELETED] results from non-patients. The party executing this
document also represents and warrants that it (i) has no reason to believe that
the submitted [DELETED] data is incorrect, and (ii) is authorized to make this
certification on behalf of all eligible Affiliates submitting [DELETED] data.

FSDC LEGAL NAME

Signature:
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Print Name:
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Print Title:
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Date:
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