<PAGE>   1
                                                                   EXHIBIT 10.41


                                      AMGEN
            AMENDMENT #2 DATED MARCH 13, 2000 TO AGREEMENT NO. 980202

Agreement No. 980202, between Amgen Inc. ("Amgen") and Renal Care Group, Inc.,
including any prior amendments thereto, shall be amended and restated in its
entirety to read as stated below.

This agreement ("Agreement") between Amgen Inc. ("Amgen") and Renal Care Group,
Inc., including the freestanding dialysis center affiliate(s) listed on Appendix
B, (collectively, "Dialysis Center"), sets forth the terms and conditions for
the purchase of EPOGEN(R) (Epoetin alfa) by Dialysis Center for the exclusive
treatment of dialysis patients.

1.       TERM OF AGREEMENT. The "Term" of this Agreement shall be defined as
         April 1, 2000 ("Commencement Date") through March 31, 2001
         ("Termination Date").

2.       DIALYSIS CENTER AFFILIATES. Dialysis Center must provide Amgen with a
         complete list of its dialysis center affiliates ("Affiliates") on or
         before the date this Agreement is executed by Dialysis Center. Only
         those Affiliates approved by Amgen and referenced in Appendix B will be
         eligible to participate under this Agreement. Modifications to the
         dialysis center Affiliates listed on Appendix B may be made pursuant to
         the request of Dialysis Center's corporate headquarters and are subject
         to approval and acknowledgment by Amgen in writing. Amgen requires no
         less than 30 days notice before the effective date of change for any
         addition or deletion of Affiliates hereunder. Amgen reserves the right
         to accept, reject, or immediately terminate any Affiliates with regard
         to participation in this Agreement if Amgen determines that such
         Affiliate is participating in any other contract or incentive with
         Amgen pertaining to the purchase of Epogen(R) or such Affiliate is not
         classified as a freestanding dialysis center or a home dialysis support
         facility.

3.       OWN USE. Dialysis Center hereby certifies that EPOGEN(R) purchased
         hereunder shall be for Dialysis Center's "own use", for the exclusive
         treatment of dialysis patients.

4.       AUTHORIZED WHOLESALERS. Dialysis Center must provide Amgen with a
         complete list of its current wholesalers, from whom Dialysis Center
         intends to purchase EPOGEN(R), and must provide the list to Amgen on or
         before the date this Agreement is executed by Dialysis Center's
         corporate headquarters. The list must include the name and complete
         address of each designated wholesaler. Wholesalers designated by
         Dialysis Center and approved by Amgen to participate in this program
         will be deemed "Authorized Wholesalers". A current listing of Dialysis
         Center's Authorized Wholesalers is referenced in Appendix B.
         Notification of proposed changes to the list of Authorized Wholesalers
         must be provided to Amgen in writing at least 30 days before the
         effective date of the proposed change. Amgen reserves the right to
         accept, reject, or immediately terminate any wholesaler with regard to
         participation in this Agreement. In the event Amgen terminates any
         Authorized Wholesaler from which Dialysis Center is purchasing
         EPOGEN(R), Amgen will work with Dialysis Center to identify other
         possible Authorized Wholesalers from which Dialysis Center may purchase
         EPOGEN(R), and/or arrange a temporary direct purchase relationship
         between Dialysis Center and Amgen until such time as an alternative
         Authorized Wholesaler can be secured by Dialysis Center. If Dialysis
         Center purchases directly from Amgen as contemplated above, Amgen shall
         be deemed an authorized Wholesaler for purposes of this Agreement.
         Dialysis Center agrees to require all Authorized Wholesalers to submit
         product sales information directly to Amgen and to a third-party sales
         reporting organization designated by Amgen.



<PAGE>   2

5.       QUALIFIED PURCHASES. Only EPOGEN(R) purchased under this Agreement by
         Dialysis Center*.

6.       COMMITMENT TO PURCHASE. Dialysis Center agrees to purchase EPOGEN(R)
         for all of its dialysis use requirements for recombinant human
         erythropoietin. Dialysis Center may purchase another brand of
         recombinant human erythropoietin for its dialysis use requirements only
         for the time, and only to the extent, that Amgen has notified Dialysis
         Center's corporate headquarters in writing that Amgen cannot supply
         EPOGEN(R) within and for the time period reasonably required by
         Dialysis Center.

7.       CONFIDENTIALITY. Both Amgen and Dialysis Center agree that this
         Agreement represents and contains confidential information which shall
         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, and then upon
         notification to the other party.

8.       DISCOUNTS. Dialysis Center may qualify for discounts and incentives in
         accordance with the schedules and terms set forth in Appendix A.
         Discounts in arrears will be paid in the form of a check payable to
         Dialysis Center's corporate headquarters. Discounts in arrears will be
         calculated in accordance with Amgen's discount calculation policies
         based on * using the prevailing * as the calculation price, except as
         otherwise provided hereunder. Upon vesting, Amgen will use its best
         efforts to make such discounts available within 30 days after receipt
         by Amgen of data, in a form acceptable to Amgen, detailing all * during
         the applicable period. Payment amounts, as calculated by Amgen, must
         equal or exceed $100.00 for the applicable period to qualify. Subject
         to the section entitled "Breach of Agreement", in the event that Amgen
         is notified in writing that Dialysis Center, and/or any Affiliates (the
         "Acquiree") is acquired by another entity or a change of control
         otherwise occurs with respect to the Acquiree, any discounts which may
         have been earned hereunder shall be paid in the form of a check payable
         to the Acquiree's corporate headquarters subject to the conditions
         described herein. If any Affiliates are added to or deleted from this
         Agreement during any of the periods used for comparison, for any of the
         discounts paid in arrears contained herein, Amgen reserves the right in
         its sole discretion to appropriately adjust Dialysis Center's discounts
         for the relevant periods, by including or excluding any purchases made
         by those Affiliates during any of those periods.

9.       TREATMENT OF DISCOUNTS. Dialysis Center agrees that it will properly
         disclose and account for any discount or other reduction in price
         earned hereunder, in whatever form, (i.e. pricing, discount, or
         incentive) 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.
         Section 1128B(b) requires that a provider of services will properly
         disclose and appropriately reflect the value of any discount or other
         reduction in price earned in the costs claimed or charges made by the
         provider under a federal health care program, as that term is defined
         in Section 1128B(f). Dialysis Center also agrees that it will (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


--------
     *   Omitted information is the subject of a request for confidential
         treatment pursuant to Rule 24b-2 under the Securities Exchange Act of
         1934 and has been filed separately with the Securities and Exchange
         Commission.




                                      -2-
<PAGE>   3

         discount. Dialysis Center's corporate headquarters agrees that it will
         advise all Affiliates, in writing, of any discount received by Dialysis
         Center's corporate headquarters hereunder with respect to purchases
         made by such Affiliates and that said Affiliates will account for any
         such discount in accordance with the above stated requirements.

10.      DATA COLLECTION. Dialysis Center agrees that all data to be provided to
         Amgen pursuant to this Agreement, shall be in a form that does not
         disclose the identity or name of any patient or other
         patient-identifying information such as address, telephone number, or
         social security number. Dialysis Center acknowledges that the data to
         be supplied to Amgen pursuant to this Agreement shall be used to
         support verification of the discounts and incentives referenced herein,
         as well as for Amgen-sponsored research concerning the role of
         EPOGEN(R) in improving treatment outcomes and quality of life of
         dialysis patients. Dialysis Center shall consistently use a unique
         alpha-numeric code (which shall not be the same as the patient's social
         security number) as a "case identifier" to track the care rendered to
         each individual patient over time, and such case identifier shall be
         included in the data provided to Amgen. The key or list matching
         patient identities to their unique case identifiers shall not be
         provided to Amgen personnel. In furtherance of Amgen research, Dialysis
         Center may agree from time to time to use its key to update the patient
         care data by linking it with information concerning health outcomes,
         quality of life, and other pertinent data that may become available to
         Amgen from other sources. Any such linking of data sources shall not
         provide the identity of any patient to Amgen. Amgen agrees that it will
         maintain data supplied under this agreement in confidence and that it
         will not use such data to identify or contact any patient. No reports
         by Amgen concerning analyses of the data or the results of such
         research shall disclose the identity of any patient.

11.      BREACH OF AGREEMENT. Either party may terminate this Agreement for
         breach upon 30 days advance written notice. In addition, in the event
         that Dialysis Center breaches any provision of this Agreement, Amgen
         shall have no obligation to continue to offer the terms described
         herein or pay any further discounts to Dialysis Center.

12.      GOVERNING LAW. This Agreement shall be governed by the laws of the
         State of California and the parties submit to the jurisdiction of the
         California courts, both state and federal.

13.      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. The party executing this Agreement on behalf of Dialysis Center
         specifically warrants and represents to Amgen that he is authorized to
         execute this Agreement on behalf of and has the power to bind Dialysis
         Center and the Affiliates to the terms set forth in this Agreement. The
         party executing this Agreement on behalf of Amgen specifically warrants
         and represents to Dialysis Center that he is authorized to execute this
         Agreement on behalf of and has the power to bind Amgen to the terms set
         forth in this Agreement.

14.      NOTICES. Any notice or other communication required or permitted
         hereunder shall be in writing and shall be deemed given or made when
         delivered in person or when sent to the other party by first class
         mail, nationally recognized overnight delivery service, or other means
         of written communication at the respective party's current address or
         at such other address as the party shall have furnished to the other in
         accordance with this provision.



                                      -3-
<PAGE>   4

15.      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 in any manner reforms, modifies, alters, restricts, or
         otherwise adversely affects the pricing of or reimbursement available
         for EPOGEN(R), Amgen may, in its sole discretion, upon 30 days notice
         (a) terminate this Agreement, or (b) exclude any Affiliates from
         participating in this Agreement unless such Affiliate(s) certifies in
         writing that they are, or will be, exempt from the provisions
         thereunder. Additionally, in order to assure compliance with any
         existing federal, state or local statute, regulation or ordinance,
         Amgen reserves the right to exclude any Affiliates from the pricing,
         discount, and incentive provisions of this Agreement if, in the opinion
         of Amgen's legal counsel such exclusion is necessary to assure such
         compliance.

16.      FORCE MAJEURE. Neither party will be liable for delays in performance
         or nonperformance of this Agreement or any covenant contained herein if
         such delay or nonperformance is a result of Acts of God, civil or
         military authority, civil disobedience, epidemics, war, failure of
         carriers to furnish transportation, strike, lockout or other labor
         disturbances, inability to obtain material or equipment, or any other
         cause of like or different nature beyond the control of such party.

17.      MISCELLANEOUS. No modification of this Agreement will be effective
         unless made in writing and executed by a duly authorized representative
         of each party, except as otherwise provided hereunder. Neither party
         may assign this Agreement to a third party without the prior written
         consent of the other party. 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.

18.      ENTIRE AGREEMENT. This Agreement constitutes the entire understanding
         between the parties and supersedes all prior written or oral proposals,
         agreements, or commitments pertaining to the subject matter herein.

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.                                   RENAL CARE GROUP, INC.


Signature:   /s/Edward Johnson               Signature:   /s/Robert Stillwell
             ---------------------                        ----------------------
Print Name:  Edward Johnson                  Print Name:  Robert Stillwell
             ---------------------                        ----------------------
Print Title:                                 Print Title: Senior Vice President
             ---------------------                        ----------------------
Date:        March 15, 2000                  Date:        March 15, 2000
             ---------------------                        ----------------------




                                      -4-
<PAGE>   5

                APPENDIX A: DISCOUNT PRICING, SCHEDULE, AND TERMS

1.       PRICING. * Contract prices do not include any wholesaler markup,
         discount or rebate, service fees, or other charges or incentives.

<TABLE>
<CAPTION>
     -------------------------------------------------------------------------------------------------------------------
                                                                                                     CONTRACT PRICE
              NDC                                            DESCRIPTION                           EFFECTIVE 4/1/2000
                                                                                                   THROUGH 3/31/2001
                                                                                                       (PER PACK)
     -------------------------------------------------------------------------------------------------------------------
     <S>                       <C>       <C>                                                       <C>
           55513-126-10        S2        2,000 Unit, 1 mL (2,000 Units/mL) single-use vial                *
                                                   10 vials/pack, 10 packs/case
     -------------------------------------------------------------------------------------------------------------------
           55513-267-10        S3        3,000 Unit, 1 mL (3,000 Units/mL) single-use vial                *
                                                   10 vials/pack, 10 packs/case
     -------------------------------------------------------------------------------------------------------------------
           55513-148-10        S4        4,000 Unit, 1 mL (4,000 Units/mL) single-use vial                *
                                                   10 vials/pack, 10 packs/case
     -------------------------------------------------------------------------------------------------------------------
           55513-144-10       S10       10,000 Unit, 1 mL (10,000 Units/mL) single-use vial               *
                                                   10 vials/pack, 10 packs/case
     -------------------------------------------------------------------------------------------------------------------
           55513-823-10       S40       40,000 Unit, 1 mL (40,000 Units/mL) single-use vial               *
                                                    10 vials/pack, 4 packs/case
     -------------------------------------------------------------------------------------------------------------------
           55513-283-10       M10       20,000 Unit, 2 mL (10,000 Units/mL) multi-use vial                *
                                                    10 vials/pack, 4 packs/case
     -------------------------------------------------------------------------------------------------------------------
           55513-478-10       M20       20,000 Unit, 1 mL (20,000 Units/mL) multi-use vial                *
                                                    10 vials/pack, 4 packs/case
     -------------------------------------------------------------------------------------------------------------------
</TABLE>

                  *

2.       OPTIONAL HEMATOCRIT INCENTIVE. Dialysis Center may qualify for an
         Optional Hematocrit/Hemoglobin Incentive ("OHI") provided the following
         requirements are met:

a.       REQUIREMENTS: Dialysis Center's aggregate * of EPOGEN(R) by all
         Affiliates as listed on Appendix B on the Commencement Date of this
         Agreement must equal or exceed *of the aggregate * of EPOGEN(R) by
         those same Affiliates for the same time period from the previous year.
         In addition, at least * of Dialysis Center's patients must have Average
         Patient Hematocrits (as defined in Section 2(b) below) greater than or
         equal to * during each calendar quarter of the Term. If either of these
         criteria is not met during any given calendar quarter of the Term,
         Dialysis Center will not qualify for the OHI during that quarter.

         In order to participate in the OHI, Dialysis Center must provide the
         following to Amgen or to a data collection vendor specified by Amgen,
         on a monthly basis, and no later than 30 days after the end of each
         month:

----------
     *   Omitted information is the subject of a request for confidential
         treatment pursuant to Rule 24b-2 under the Securities Exchange Act of
         1934 and has been filed separately with the Securities and Exchange
         Commission.


                                      A-1
<PAGE>   6

         i)       all hematocrit test results for each dialysis patient, the
                  date of each test, and a consistent, unique, alpha-numeric
                  identifier (sufficient to consistently track an individual
                  patient without in any way disclosing the identity of the
                  patient), along with the name, address and phone number of the
                  particular Affiliate at which each patient received treatment
                  (collectively the "Data"). Amgen may utilize the Data for any
                  purpose, and reserves the right to audit all Data. 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. The hematocrit test results
                  mustbe derived from blood samples taken immediately before
                  dialysis treatment using any automated red blood cell counter
                  testing method (e.g. Coulter-counter, Bayer-Technicon, Sysmex,
                  CellDyne), must be reported to the nearest tenth of one
                  percent, and must be submitted directly from the clinical
                  laboratory in a format reasonably acceptable to Amgen. Hand
                  written reports are not acceptable; electronic submission of
                  the Data is preferred, and

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

b.       CALCULATION: Assuming Dialysis Center has fulfilled all requirements as
         described in Section 2(a) above, Dialysis Center's OHI payment will be
         calculated as follows:

         The "Average Patient Hematocrit" for each dialysis patient will be
         based upon the average of all hematocrit test results gathered for each
         patient during each calendar quarter of the Term. The Average Quarterly
         Percentage of all dialysis patients with Average Patient Hematocrits
         greater than or equal to * will be determined by dividing the total
         number of dialysis patients with Average Patient Hematocrits greater
         than or equal to * by the total number of dialysis patients treated by
         Dialysis Center. The OHI will be calculated based on Dialysis Center's
         overall performance in accordance with Amgen's discount calculation
         policies.

c.       PAYMENT: The OHI will be calculated on a quarterly basis and paid to
         Dialysis Center's corporate headquarters, except as otherwise provided
         hereunder. Payment is contingent upon receipt by Amgen of the "Annual
         Certification Letter" and all required monthly Data for the
         corresponding quarter. If Data is received more than thirty days after
         the last day of any month within a given calendar quarter, the total *
         of EPOGEN(R) attributable to Dialysis Center during such month will be
         excluded from the calculation of the OHI for that quarter.
         Notwithstanding the foregoing, if Amgen receives all required data from
         a minimum of * of all entities within the definition of "Dialysis
         Center" within the time frame referenced above for any month within a
         given calendar quarter, the total * of EPOGEN(R) attributable to
         Dialysis Center during such month, will be included in the calculation
         of the OHI for that quarter. However, if Amgen determines that any
         Affiliate is consistently not submitting the required Data, Amgen
         reserves the right in its sole discretion to exclude such Affiliate's *
         of EPOGEN(R) from the calculation of the OHI for any relevant quarter.
         Quarterly OHI payments will be based upon the Data received from the
         previous quarter, and will equal * during that quarter (exclusive of
         any * of EPOGEN(R) made by Dialysis Center or any Affiliate not meeting
         the Data submission requirements described above) as governed by the

--------
     *   Omitted information is the subject of a request for confidential
         treatment pursuant to Rule 24b-2 under the Securities Exchange Act of
         1934 and has been filed separately with the Securities and Exchange
         Commission.


                                      A-2
<PAGE>   7

         OHI schedule listed below. Notwithstanding the foregoing, payment for
         any period during the Term that is not equivalent to a complete
         calendar quarter, will be based on an average of the Data that is
         available for that period. If the EPOGEN(R) package insert language
         changes, then Amgen and Dialysis Center agree to negotiate in good
         faith a reasonable amendment to the OHI provisions of this Agreement to
         address any such change, if necessary. In addition, at the end of the
         Term of this Agreement, Amgen will conduct an analysis to determine if
         Dialysis Center has achieved the required * growth rate (contemplated
         by Section 2(a) above) throughout the Term of the Agreement. If
         Dialysis Center has achieved the required * growth rate, Amgen will
         reconcile all previous OHI calculations and appropriately adjust the
         OHI for all relevant quarters during the Term in which an OHI was not
         earned.
<TABLE>
<S>                                                                    <C>
   AVERAGE QUARTERLY PERCENTAGE OF ALL DIALYSIS PATIENTS               OPTIONAL HEMATOCRIT
 WITH AVERAGE PATIENT HEMATOCRITS GREATER THAN OR EQUAL TO *           INCENTIVE PERCENTAGE
PLEASE DIRECT YOUR ATTENTION TO THE EPOGEN(R) PACKAGE INSERT
</TABLE>
                                       *

d.       VESTING: Dialysis Center's OHI will vest on the last day of the
         corresponding quarter.

e.       HEMOGLOBIN CONVERSION: Dialysis Center may choose to submit hemoglobin
         test results rather than hematocrit test results as a measurement of
         anemia. If during the Term, Dialysis Center elects to use hemoglobin
         test results, Dialysis Center must: i) submit a "Notification Letter"
         to Amgen, a sample of such Notification Letter is attached hereto as
         Exhibit #2, and ii) begin submitting all hemoglobin test results for
         all dialysis patients along with all other information described in
         Section 2(a) above, rather than hematocrit test results for all
         dialysis patients at each Affiliate for purposes of participating in
         the OHI.

         Amgen will accept the hemoglobin test results, multiply each test
         result by *, and apply the converted results to the same schedule,
         requirements, and calculations described above in place of the
         hematocrit test results.

         For the calendar quarter in which Dialysis Center submits its
         Notification Letter ("Grace Period"), Amgen will apply Dialysis
         Center's Average Quarterly Percentage from the last calendar quarter in
         which complete hematocrit test results were received ("AQP-Hematocrit")
         to the OHI schedule listed above in order to determine the applicable
         OHI Percentage earned by Dialysis Center. If Dialysis Center's overall
         performance on the OHI after the Grace Period does not equal or exceed
         the overall performance by Dialysis Center prior to conversion to
         hemoglobin, Amgen will continue to apply each Affiliate's
         AQP-Hematocrit through the remainder of the Term, provided that during
         the time period the AQP-Hematocrit is applied, *.

         In the event any Affiliates still submitting Data based on hematocrit
         test results are added to this Agreement after Dialysis Center has
         converted to hemoglobin, such Affiliate's * of EPOGEN(R), for the
         calendar quarter in which they were added, shall be included in the
         calculation of the OHI payment. In order for such added Affiliates' *
         of EPOGEN(R) to be included in all subsequent OHI payment calculations,
         such Affiliate must submit hemoglobin test results rather than
         hematocrit.

----------
     *   Omitted information is the subject of a request for confidential
         treatment pursuant to Rule 24b-2 under the Securities Exchange Act of
         1934 and has been filed separately with the Securities and Exchange
         Commission.


                                      A-3
<PAGE>   8
 3.       ELECTRONIC DATA DISCOUNT. Dialysis Center shall be eligible to receive
         a * if certain data elements are transmitted to Amgen electronically.
         The * will be calculated as a percentage of the * of EPOGEN(R)
         attributable to Dialysis Center during each quarter. In order to
         qualify for the *, the following EPOGEN(R) Related Patient Data must be
         submitted by all Affiliates in an electronic format reasonably
         acceptable to Amgen (such as: Excel; Lotus 123.wk1; or text file that
         is tab delimited, comma delimited, or space delimited): Facility ID,
         Patient ID (sufficient to consistently track an individual patient
         without in any way disclosing the identity of the patient), Draw Date,
         Hematocrit, Hemoglobin, Transferrin Saturation, and Ferritin. Such
         EPOGEN(R) Related Patient Data must be submitted, on a monthly basis,
         and no later than 30 days after the end of each month. If such
         EPOGEN(R) Related Patient Data is received more than thirty days after
         the last day of any month within a given calendar quarter, the total *
         of EPOGEN(R) attributable to Dialysis Center during such month will be
         excluded from the calculation of the * for that quarter.
         Notwithstanding the foregoing, if Amgen receives all required data from
         a minimum of * of all entities within the definition of "Dialysis
         Center" within the time frame referenced above for any month within a
         given calendar quarter, the total * of EPOGEN(R) attributable to
         Dialysis Center during such month, will be included in the calculation
         of the * for that quarter. However, if Amgen determines that any
         Affiliate is consistently not submitting the required data, Amgen
         reserves the right in its sole discretion to exclude such Affiliate's *
         of EPOGEN(R) from the calculation of the * for any relevant quarter.
         The Electronic Data Discount will vest on the last day of the
         corresponding quarter, and will be paid 30 days thereafter.

4.       VOLUME PERFORMANCE INCENTIVE. Dialysis Center may qualify for the
         Volume Performance Incentive ("VPI") as described below.

a.       CALCULATION: Dialysis Center's VPI will be calculated in accordance
         with the following formula.

                                       *

         Estimated payments will be made quarterly using Amgen's discount
         calculation policies, and the VPI will be reconciled at the end of the
         Term.

b.       VESTING: Dialysis Center's VPI will vest quarterly.

----------
     *   Omitted information is the subject of a request for confidential
         treatment pursuant to Rule 24b-2 under the Securities Exchange Act of
         1934 and has been filed separately with the Securities and Exchange
         Commission.




                                      A-4
<PAGE>   9

                 APPENDIX B: LIST OF DIALYSIS CENTER AFFILIATES

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.

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

Henry Schein, Inc.
135 Duryea Road
Nelville, NY  11747

Priority HealthCare Corporation
285 West Central Parkway, Suite 1704
Altamonte Springs, FL  32714





                                      B-1
<PAGE>   10

                                                                      EXHIBIT #1


                       SAMPLE ANNUAL CERTIFICATION LETTER



Month X, 199X

FSDC Legal Name
Street Address
City, ST  Zip

RE:  EPOGEN(R) (Epoetin alfa) Agreement No. 9XXXXX

Dear ____________:

Thank you for your participation in the Optional Hematocrit/Hemoglobin 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
(805) 447-4134. Thank you for your assistance in returning this certification.

Sincerely,



Sue Simon
Outcomes Incentive Analyst


CERTIFICATION:

On behalf of FSDC Legal Name and all eligible Affiliates participating in the
Optional Hematocrit/Hemoglobin Incentive Program under Agreement No. XXXXXX, the
undersigned hereby certifies that the hematocrit/hemoglobin data and any other
data required to be submitted (herein referred to as "Data"), for each eligible
Affiliate during the term of this Agreement includes the required Data from all
dialysis patients from each such Affiliate, and does not include Data from
non-patients. The party executing this document also represents and warrants
that it (i) has no reason to believe that the submitted Data is incorrect, and
(ii) is authorized to make this certification on behalf of all eligible
Affiliates submitting Data.

FSDC LEGAL NAME

Signature:        _____________________________
Print Name:       _____________________________
Print Title:      _____________________________
Date:             _____________________________


<PAGE>   11


                                                                      EXHIBIT #2


                           SAMPLE NOTIFICATION LETTER


Month X, 199X

Ms. Sue Simon
Outcomes Incentive Analyst
Amgen Inc./Contract Sales Department
One Amgen Center Drive/Mail Stop 37-2-A
Thousand Oaks, CA  91320

RE:  Amgen Agreement No. XXXXXX

Dear Ms. Simon:

This letter serves as notification that FSDC Legal Name and all eligible
Affiliates participating in the Optional Hematocrit/Hemoglobin Incentive Program
under Agreement No. XXXXXX, will begin using hemoglobin test results as a
measurement of anemia as of Month X, 199X, and will begin submitting hemoglobin
test results rather than hematocrit test results for purposes of participating
in the Optional Hematocrit/Hemoglobin Incentive Program.

We understand that any discount under the Optional Hematocrit/Hemoglobin
Incentive Program will now be based solely on hemoglobin test results and that
hematocrit test results will no longer be accepted. We also understand that such
hemoglobin test results will be converted and applied to the same schedule,
requirements, and calculations described in the Optional Hematocrit/Hemoglobin
Incentive Program outlined in the Agreement.


Sincerely,



Name of Administrator
Title