<PAGE>   1
                                                                    EXHIBIT 10.8

                                 AMENDMENT NO. 3


                         DATED AS OF SEPTEMBER 16, 1999


                                       TO


                      SECOND AMENDED AND RESTATED REVOLVING
                           LOAN AND SECURITY AGREEMENT


                          DATED AS OF NOVEMBER 21, 1997



                                      AMONG


                          SPECIALTY CARE NETWORK, INC.

                             SCN OF PRINCETON, INC.

                                       AND


                             BANK OF AMERICA, N.A.,
                                  AMSOUTH BANK,
                                    PARIBAS,
                           KEY CORPORATE CAPITAL, INC.

                                       AND


                         BANK OF AMERICA, N.A., AS AGENT




<PAGE>   2



                                TABLE OF CONTENTS

<TABLE>
<S>                                                                        <C>
1.  Definitions..............................................................1

2.  Amendments to Agreement..................................................2

3.  Representations and Warranties...........................................4
    3.1      Incorporation...................................................4
    3.2      Due Authorization, No Conflicts, Etc............................5
    3.3      Due Execution, Etc..............................................5

4.  Conditions Precedent.....................................................6
    4.1      Conditions Precedent to Effectiveness of Amendment No. 3........6

5.  Effectiveness of Amendment No. 3.........................................7

6.  Closing..................................................................8

7.  Governing Law, Etc.......................................................8

8.  Section Titles and Table of Contents.....................................8

9.  Arbitration..............................................................8

10. Counterparts............................................................10

11. Agreement to Remain in Effect...........................................10
</TABLE>



                                      -i-
<PAGE>   3



         This Amendment No. 3 to Second Amended and Restated Revolving Loan and
Security Agreement, made and entered into as of this 16th day of September,
1999, by and among Specialty Care Network, Inc. (the "Borrower"); the
Guarantors, jointly and severally; the various banks and lending institutions on
the signature pages attached hereto together with all assignees of such banks
and lending institutions (each a "Bank" and collectively the "Banks"); and Bank
of America, N.A., successor to NationsBank, N.A., successor to NationsBank of
Tennessee, N.A., as agent (the "Agent").

                              W I T N E S S E T H :

         WHEREAS, the Borrower, the Guarantors, the Banks, the Swingline Bank,
and the Agent entered into a certain Second Amended and Restated Revolving Loan
and Security Agreement dated as of November 21, 1997, as amended by Amendment
No. 1 thereto dated March 30, 1998 and Amendment No. 2 thereto dated April 1,
1998 (collectively the "Loan Agreement"); and

         WHEREAS, the parties to the Loan Agreement desire to amend the existing
Loan Agreement to convert it from a revolving loan facility to a term loan
facility, to eliminate the Swingline Bank and Swingline Loan, to delete the
existing financial ratios, to add Healthcare Report Cards, Inc., as a Guarantor,
to pledge additional collateral, and to modify certain of the negative
covenants, all as hereinafter more specifically set forth;

         NOW THEREFORE, in consideration of the foregoing and the mutual
covenants and agreements set forth herein, and for other good and valuable
consideration, the receipt and legal sufficiency of which are hereby
acknowledged, the parties hereto agree as follows:

         1. DEFINITIONS. All capitalized terms used in this Amendment No.3 which
are not otherwise defined herein shall have the respective meanings ascribed
thereto in the Agreement.


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<PAGE>   4



         2. AMENDMENTS TO AGREEMENT.

         2.1 In the Exhibits to the Agreement, EXHIBIT A, being the "Form of
Notes", is hereby amended by replacing the Notes attached thereto with the
modified and renewed Term Loan Notes attached hereto as Replacement EXHIBIT A.

         2.2 Section I of the Agreement, DEFINITIONS, is hereby amended by
deleting "NOTICE OF BORROWING", "NOTICE OF CONVERSION", "PERMITTED ACQUISITION",
"PERMITTED ACQUISITION INDEBTEDNESS", "PERMITTED ACQUISITION Price", "REVOLVING
LOANS", "SWINGLINE BANK", "SWINGLINE COMMITMENT", "SWINGLINE COMMITTED AMOUNT",
"SWINGLINE Loan", "SWINGLINE NOTE", and "UNUTILIZED LOAN COMMITMENT", and by
adding thereto the following new definitions as follows:

                  "AMENDMENT NO. 3 EFFECTIVE DATE" has the meaning specified in
Section 5 of Amendment No. 3.

                  "TERM LOANS" means those term loans made pursuant to Paragraph
2.1 hereof.

         In addition to the foregoing new definitions, the following definitions
are hereby amended: "COMMITTED AMOUNT" is hereby amended to equal that amount
set forth opposite each Bank=s signature hereto, which amount is for a Term Loan
only; "GUARANTOR" is hereby amended to add Healthcare Report Cards, Inc. as a
Guarantor; "COLLATERAL DOCUMENTS" and "PLEDGED INSTRUMENTS" are hereby amended
to add the Pledge Agreement required to be executed by Healthcare Report Cards,
Inc. pursuant to Paragraph 4.1(f) hereof and the stock pledged thereby,
respectively, and "TOTAL COMMITMENTS" is hereby amended to replace Seventy-Five
Million and No/100 Dollars ($75,000,000.00) with the figure of Twelve Million
Five Hundred Thousand and No/100 Dollars ($12,500,000.00).



                                      -2-
<PAGE>   5



         2.3 Paragraphs 2.1 through and including 2.11 are hereby deleted in
their entirety. Remaining Paragraph 2.12 is hereby re-numbered 2.2, and there is
hereby inserted a new Paragraph 2.1 as follows:

         "2.1 TERM LOANS. Subject to the terms and conditions of and relying
         upon the representations, warranties and covenants contained in this
         Agreement, each Bank severally agrees to convert its existing revolving
         loans to the Borrower to Term Loans until the Termination Date, said
         Term Loans to be evidenced by the Term Loan Notes attached hereto as
         Replacement EXHIBIT A. Said Term Loans shall amortize and be payable at
         the times and at the rates set forth in said Notes; provided, on or
         before December 31, 1999, the Borrower shall also pay to the Banks to
         be applied on a prorata basis the greater of: (i) one hundred percent
         (100%) of all "true-up" proceeds received from the reconciliation of
         the current assets and liabilities of practices disposed of prior to
         September 3, 1999, or (ii) Two Hundred Fifty Thousand and No/100
         Dollars ($250,000.00). As restructured hereby, there shall be no
         Swingline Loan Subfacility nor Letter of Credit Facility, and Borrower
         hereby certifies to the Banks that there are no outstanding Letters of
         Credit issued and outstanding under the Agreement.

         2.4 Paragraphs 3.2 and 3.3 in the Agreement are hereby deleted in their
entirety, and Paragraph 3.4 is hereby re-numbered as Paragraph 3.2.

         2.5 Paragraph 6.16 of the Agreement is hereby deleted in its entirety.

         2.6 Paragraph 7.5 is hereby amended to delete subparagraph (6) thereof
in its entirety and to re-number subparagraphs (7) and (8) as subparagraphs (6)
and (7).

         2.7 Paragraph 7.10 is hereby amended to delete subparagraph (3) thereof
in its entirety and to re-number subparagraph (4) as subparagraph (3).

         2.8 Paragraph 7.13 is hereby deleted in its entirety and replaced with
the following subparagraph 7.13:

         "7.13 ACQUISITIONS. Neither the Borrower nor any Subsidiary will make
         any Acquisition without first obtaining the prior written consent of
         the Majority Banks.



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         2.9 The Swingline Bank is hereby deleted as a party to the Agreement
(although Bank of America, N.A. remains as a party to the Agreement in its other
capacities), and Healthcare Report Cards, Inc. is hereby added to the Agreement
as a Guarantor thereunder. In addition, all references in this Agreement to
Revolving Loans are hereby replaced with references to Term Loans, including any
references in the title of this Agreement, this Agreement being hereafter
entitled the "Second Amended and Restated Term Loan and Security Agreement".

         3. REPRESENTATIONS AND WARRANTIES. To induce the Banks and the Agent to
enter into this Amendment No. 3, the Borrower and Guarantors jointly and
severally represent and warrant to the Banks and the Agent as follows:

         3.1 INCORPORATION. Specialty Care Network, Inc. is a corporation duly
organized, validly existing and in good standing under the laws of the State of
Delaware; has the corporate power to own its properties and to engage in the
business it conducts, and is duly qualified and in good standing as a foreign
corporation in the jurisdictions wherein the nature of its business or the
ownership of its properties requires it to be so qualified. SCN of Princeton,
Inc. is a corporation duly organized, validly existing and in good standing
under the laws of the State of Delaware; has the corporate power to own its
properties and to engage in the business it conducts, and is duly qualified and
in good standing as a foreign corporation in the jurisdictions wherein the
nature of its business or the ownership of its properties requires it to be so
qualified. Healthcare Report Cards, Inc. is a corporation duly organized,
validly existing and in good standing under the laws of the State of Delaware;
has the corporate power to own its properties and to engage in the business its
conducts, and is duly qualified and in good standing as a foreign corporation in
the jurisdictions wherein the nature of its business or the ownership of its
properties requires it to be so qualified.



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         3.2 DUE AUTHORIZATION, NO CONFLICTS, ETC. The execution, delivery and
performance by the Borrower and Guarantors of this Amendment No. 3 and any and
all other agreements, instruments and documents to be executed and/or delivered
by the Borrower and Guarantors pursuant hereto or in connection herewith, and
the consummation by the Borrower and Guarantors of the transactions contemplated
hereby or thereby: (a) are within their respective corporate powers; (b) have
been duly authorized by all necessary corporate action, including without
limitation, the consent of stockholders where required; (c) do not and will not
conflict with or result in any breach of, or constitute with the passage of time
or the giving of notice or both, a default under (i) any Requirement of Law or
(ii) any agreement to which Borrower or any Guarantor is a party or by which
they, or any of their respective property, is bound; and (d) do not require the
consent, authorization by, or approval of, or notice to, or filing or
registration with, any governmental authority or any other Person other than
those which have been obtained and copies of which have been delivered to the
Agent pursuant to Subsection 4.1(a)(ii) hereof, each of which is in full force
and effect.

         3.3 DUE EXECUTION, ETC. This Amendment No. 3 and each of the other
agreements, instruments and documents to be executed and/or delivered by the
Borrower or any Guarantor pursuant hereto or in connection herewith (a) has been
duly executed and delivered, and (b) constitutes the legal, valid and binding
obligation of the Borrower and each Guarantor, enforceable against it in
accordance with its terms, subject however to state and federal bankruptcy,
insolvency, reorganization and other laws and general principles of equity
affecting enforcement of the rights of creditors generally.



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<PAGE>   8

         4. CONDITIONS PRECEDENT. The effectiveness of this Amendment No. 3 is
subject to the fulfillment of the following conditions precedent on or prior to
the Amendment No. 3 Effective Date (as hereinafter defined in Section 5 hereof):

         4.1 CONDITIONS PRECEDENT TO EFFECTIVENESS OF AMENDMENT NO. 3. The Agent
shall have received, on or prior to the Amendment No. 3 Effective Date, the
following, each dated on or prior to the Amendment No. 3 Effective Date unless
otherwise indicated, in form and substance satisfactory to the Agent and in
sufficient copies for each Bank:

                  (a) Certified copies of (i) the resolutions of the Board
of Directors of the Borrower and each Guarantor approving this Amendment No. 3
and each other agreement, instrument or document to be executed by it pursuant
hereto or as contemplated hereby, and (ii) all documents evidencing other
necessary corporate action and required governmental and third party approvals,
licenses and consents with respect to this Amendment No. 3 and the transactions
contemplated hereby.

                  (b) A certificate of the Secretary or an Assistant
Secretary of Borrower and each Guarantor certifying the names and true
signatures of the officers of Borrower and each Guarantor who have been
authorized to execute on behalf of Borrower and each Guarantor this Amendment
No. 3 and any other agreement, instrument or document executed or to be executed
by Borrower or any Guarantor in connection herewith.

                  (c) A certificate dated the Amendment No. 3 Effective
Date signed by the President or any Vice-President of Borrower, to the following
effect:



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<PAGE>   9

                           (i) The representations and warranties of the
         Borrower contained in Sections 3.1, 3.2, and 3.3 of this Amendment No.
         3 are true and correct on and as of such date as though made on and as
         of such date;

                           (ii) No Default or Event of Default has occurred and
         is continuing, and no Default or Event of Default would result from the
         execution and delivery of this Amendment No. 3 or the other agreements,
         instruments and documents contemplated hereby; and

                           (iii) The Borrower has paid or agreed to pay all
         amounts payable by it pursuant to the Agreement as amended hereby
         (including, without limitation, all legal fees and expenses of Banks'
         counsel incurred in connection herewith) to the extent then due and
         payable.

                  (d) Executed Term Loan Notes in the form attached hereto as
Replacement EXHIBIT A.

                  (e) Executed Guaranty and Suretyship Agreement of Healthcare
Report Cards, Inc., in substantially the form of EXHIBIT 1 hereto.

                  (f) Executed Pledge Agreement executed by Healthcare Report
Cards, Inc. in favor of the Agent for the benefit of the Banks, in substantially
the form of EXHIBIT 2 hereto.

                  (g) A favorable opinion of Messrs. Baker Donelson Bearman &
Caldwell, counsel to the Borrower, in substantially the form of EXHIBIT 3
hereto, and as to such other matters as any Bank, through the Agent, may
reasonably request.

         5. EFFECTIVENESS OF AMENDMENT NO. 3. This Amendment No. 3 shall become
effective at such time as (a) each of the conditions precedent set forth in
Section 4.1 hereof shall



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<PAGE>   10

have been satisfied, and (b) counterparts of this Amendment No. 3, executed and
delivered by the Borrowers, the Guarantors, the Banks, and the Agent shall have
been received by the Agent (or, alternatively, confirmation of the execution
hereof by such parties shall have been received by the Agent). The date upon
which the conditions described in clauses (a) and (b) of the foregoing sentence
shall have been fulfilled is referred to herein as the "Amendment No. 3
Effective Date".

         6. CLOSING. The Closing under this Amendment No. 3 shall occur on the
Amendment Effective Date at the offices of Boult, Cummings, Conners & Berry,
PLC, 414 Union Street, Nashville, Tennessee 37219, or such other location as the
parties may agree.

         7. GOVERNING LAW, ETC. This Amendment No. 3 shall be governed by, and
construed in accordance with, the laws of the State of Tennessee as provided in
Section 10.9 of the Agreement, which Section is incorporated herein by reference
and made a part hereof as though set forth in full herein.

         8. SECTION TITLES AND TABLE OF CONTENTS. The Section Titles and Table
of Contents contained in this Amendment No. 3 are and shall be without
substantive meaning or content of any kind whatsoever and are not a part of the
agreement among the parties hereto.

         9. ARBITRATION. Any controversy or claim between or among the parties
hereto including but not limited to those arising out of or relating to this
Instrument, Agreement or document or any related instruments, agreements or
documents, including any claim based on or arising from an alleged tort, shall
be determined by binding arbitration in accordance with the Federal Arbitration
Act (or if not applicable, the applicable state law), the Rules of Practice and
Procedure for the Arbitration of Commercial Disputes of Judicial Arbitration and
Mediation Services, Inc. (J.A.M.S.), and the "Special Rules" set forth below. In
the event of any



                                      -8-
<PAGE>   11

inconsistency, the Special Rules shall control. Judgment upon any arbitration
award may be entered in any court having jurisdiction. Any party to this
Agreement may bring an action, including a summary or expedited proceeding, to
compel arbitration of any controversy or claim to which this agreement applies
in any court having jurisdiction over such action.

                  (a) Special Rules. The arbitration shall be conducted in the
city of the Borrower=s domicile at the time of the execution of this instrument,
agreement or document and administered by J.A.M.S. who will appoint an
arbitrator; if J.A.M.S. is unable or legally precluded from administering the
arbitration, then the American Arbitration Association will serve. All
arbitration hearings will be commenced within 90 days of the demand for
arbitration; further, the arbitrator shall only, upon a showing of cause, be
permitted to extend the commencement of such hearing for up to an additional 60
days. In any such arbitration, the prevailing party will be awarded attorney's
fees, costs of arbitration and all out-of-pocket expenses against the defaulting
party.

                  (b) Reservation of Rights. Nothing in this instrument,
agreement or document shall be deemed to (i) limit the applicability of any
otherwise applicable statutes of limitation or repose or any waivers contained
in this Agreement; or (ii) be a waiver by the Agent or Banks of the protection
afforded to them by 12 U.S.C. ' 91 or any substantially equivalent state law; or
(iii) limit the right of the Agent or Banks hereto (A) to exercise self help
remedies such as (but not limited to) set off, or (B) to foreclose against any
real or personal property collateral, or (C) to obtain from a court provisional
or ancillary remedies such as (but not limited to) injunctive relief, writ of
possession or the appointment of a receiver. The Agent or Banks may exercise
such self help rights, foreclose upon such property, or obtain such provisional
or ancillary remedies before, during or after the pendency of any arbitration
proceeding brought pursuant to this instrument,



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<PAGE>   12

agreement or document. Neither this exercise of self help remedies nor the
institution or maintenance of an action for foreclosure or provisional or
ancillary remedies shall constitute a waiver of the right of any party,
including the claimant in any such action, to arbitrate the merits of the
controversy or claim occasioning resort to such remedies.

         10. COUNTERPARTS. This Amendment No.3 may be executed in any number of
counterparts and by different parties hereto in separate counterparts, each of
which when so executed shall be deemed to be an original and all of which taken
together shall constitute one and the same instrument.

         11. AGREEMENT TO REMAIN IN EFFECT. Except as expressly provided herein,
the Agreement and each other Collateral Document shall be and shall continue in
full force and effect in accordance with its respective terms.

         IN WITNESS WHEREOF, the parties hereto have caused this Amendment No. 3
to be executed by their respective officers thereunto duly authorized, as of the
date first above written.


                                   BORROWER

                                   SPECIALTY CARE NETWORK, INC.


                                   BY:
                                      --------------------------------
                                   TITLE:
                                         -----------------------------


                                   GUARANTORS AND SUBSIDIARIES

                                   SCN OF PRINCETON, INC.


                                   BY:
                                      --------------------------------
                                   TITLE:
                                         -----------------------------



                                      -10-
<PAGE>   13



                                   HEALTHCARE REPORT CARDS, INC.


                                   BY:
                                      --------------------------------
                                   TITLE:
                                         -----------------------------


                                   BANKS


Committed Amount:                  BANK OF AMERICA, N.A., successor to
$5,000,000.00                      NationsBank, N.A., successor to NationsBank
                                   of Tennessee, N.A., as Agent


                                   BY:
                                      --------------------------------
                                   TITLE:
                                         -----------------------------


Committed Amount:                  AMSOUTH BANK
$2,500,000.00

                                   BY:
                                      --------------------------------
                                   TITLE:
                                         -----------------------------


Committed Amount:                  PARIBAS
$2,500,000.00


                                   BY:
                                      --------------------------------
                                   TITLE:
                                         -----------------------------




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<PAGE>   14

Committed Amount:                  KEY CORPORATE CAPITAL INC.,
$2,500,000.00                      A MICHIGAN CORPORATION


                                   BY:
                                      --------------------------------
                                   TITLE:
                                         -----------------------------


                                   AGENT
                                   BANK OF AMERICA, N.A., AS AGENT


                                   BY:
                                      --------------------------------
                                   TITLE:
                                         -----------------------------

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