<PAGE>

                                                                  EXHIBIT 10.1.6

                                                                  EXECUTION COPY

                         SIXTH AMENDMENT AND WAIVER AGREEMENT


         SIXTH AMENDMENT AND WAIVER AGREEMENT dated as of January 8, 1997 (this
"Amendment") among Physician Corporation of America (the "Borrower"), the banks
listed on the signature pages hereof (the "Lenders"), Citibank, N.A., as issuing
bank (the "Issuing Bank"), and Citibank, N.A., as agent for the Lenders and
Issuing Bank (the "Agent").


PRELIMINARY STATEMENTS:

         1.   The Borrower, the Lenders, the Issuing Bank and the Agent are
parties to that certain Revolving Credit Agreement dated as of October 27, 1994,
as amended by an Amendment to Credit Agreement and Consent to Acquisition dated
as of September 22, 1995, by a Second Amendment to Credit Agreement dated as of
March 29, 1996, by a Third Amendment to Credit Agreement dated as of April 5,
1996, by a Fourth Amendment and Consent Agreement dated as of June 10, 1996 and
by a Fifth Amendment and Waiver Agreement dated as of November 25, 1996 (the
"Fifth Amendment"; such Revolving Credit Agreement, as so amended and as further
amended, supplemented or otherwise modified and in effect from time to time
being the "Credit Agreement").  Capitalized terms defined in the Credit
Agreement and not otherwise defined herein are used herein as therein defined;
and capitalized terms defined in Sections 1 and 2 hereof are used elsewhere
herein as so defined (without regard to the conditions to effectiveness in
Sections 5 and 6 hereof).

         2.   Pursuant to the Credit Agreement, as a result of the amendments
provided for in the Fifth Amendment, the Termination Date occurred on December
31, 1996 because of the Borrower's failure to have entered into the Refinancing
Commitment and otherwise to have satisfied the conditions provided for in
Section 7 of the Fifth Amendment as of such date.  Accordingly, all Obligations
became due and payable in full on December 31, 1996, including the termination
fee payable on the Fifth Amendment Termination Date as provided in Section 8(f)
of the Fifth Amendment.  The Borrower has not paid the Obligations in full.
Accordingly, interest on all Obligations has been accruing from December 31,
1996 at the default rate as provided in Section 2.07(b) of the Credit Agreement.

         3.   The Borrower has requested that the Issuing Bank and the Lenders
(i) waive the occurrence of the Termination Date and Fifth Amendment Termination
Date, the Borrower's failure to pay the Obligations in full on December 31, 1996
and the requirement that the Borrower pay interest accruing on the Obligations
at the default rate from December 31, 1996 and (ii) extend the deadline for
satisfaction of the conditions of Section 7 of the Fifth Amendment and modify
the requirements as to what will constitute the Refinancing

<PAGE>

                                          2

Commitment to be provided pursuant to such Section 7, in each on the terms and
subject to the conditions hereof.

         4.   The Borrower proposes to effect the above waivers and
modifications subject to either one of two alternative sets of terms and
conditions and otherwise as provided herein.  Under one alternative (the
"Principal Paydown Alternative") the Borrower proposes (i) to borrow from Sierra
the principal amount of $16,750,000 pursuant to a promissory note and related
documents providing for such borrowing (collectively, the "Sierra Subordinated
Note") to be subordinated to the Obligations and secured by liens junior to the
liens securing the Obligations, in each case on terms satisfactory to the
Lenders, the Issuing Bank and the Agent, (ii) pay over the proceeds of the
borrowing under the Sierra Note for application toward the installment of
principal of the Revolving Advances that became payable on December 31, 1996
under Section 2.10(a)(i) of the Credit Agreement and (iii) give effect to such
other terms as are provided for in Section 1 hereof.

         5.   Under the alternative set of terms and conditions (the "Pricing
Increase Alternative"), the Borrower proposes to (i) increase the interest rates
payable under the Credit Agreement and the termination fee provided for in
Section 8(f) of the Fifth Amendment and (ii)  give effect to such other terms as
are provided for in Section 2 hereof.

         6.     The Issuing Bank and the Lenders are willing to agree to either
of the alternative sets of waivers and modifications requested by the Borrower,
in each case on the terms and subject to the conditions hereof.

         NOW, THEREFORE, in consideration of the premises and mutual agreements
set forth herein, the parties hereto agree as follows:

         SECTION 1.  PRINCIPAL PAYDOWN ALTERNATIVE WAIVERS AND AMENDMENTS.
(a)   PRINCIPAL PAYDOWN ALTERNATIVE WAIVERS.     (i)   The Issuing Bank and the
Lenders hereby waive (A) any occurrence of the Termination Date or Fifth
Amendment Termination Date prior to the Sixth Amendment A Effective Date (as
defined in Section 5 below) resulting solely from the Borrower's failure to
satisfy the conditions of Section 7 of the Fifth Amendment, (B) any failure of
the Borrower to make any payment that became payable solely as a result of any
such occurrence and (C) any requirement that the Borrower pay interest at the
default rate under Section 2.07(b) of the Credit Agreement accruing for the
period from December 31, 1996 until the Sixth Amendment A Effective Date on
Obligations that became due and payable solely as a result of any such
occurrence.

         (ii) The Issuing Bank and the Lenders hereby waive the Borrower's
    compliance with the covenants of Section 6.02(a) and 6.02(c) of the Credit
    Agreement to the extent that such covenant would otherwise be violated by
    the Borrower creating, incurring or suffering to exist the Debt evidenced
    by the Sierra Note or liens

<PAGE>

                                          3

    securing such Debt, provided that the Debt under the Sierra Note is
    subordinate to the Obligations and the liens securing such Debt are junior
    to the liens securing the Obligations, in each case on terms and pursuant
    to documentation that has been approved by the Agent, all of the Lenders
    and the Issuing Bank in their sole and absolute discretion.

         (b)  PRINCIPAL PAYDOWN ALTERNATIVE AMENDMENTS.    (i)   (A)   The
    definition of Applicable Base Rate Margin" set forth in Section 1.01 of the
    Credit Agreement is hereby amended in its entirety so as to read in full as
    follows:

                   "'APPLICABLE BASE RATE MARGIN' means, at all times after
              December 31, 1996, 0.00%."

              (B)  Clause (ii) of the definition of "Fifth Amendment
         Termination Date" set forth in Section 1.01 of the Credit Agreement is
         hereby amended in its entirety so as to read in full as follows:

                   "(ii)     February 17, 1997, if the conditions of Section 7
              of the Fifth Amendment have not been satisfied in full on or
              before such date;"

              (C)  Clause (iii) of the definition of "Fifth Amendment
         Termination Date" set forth in Section 1.01 of the Credit Agreement is
         hereby amended in its entirety so as to read in full as follows:

                   "(iii)    any date on which (A) the commitment under the
              Refinancing Commitment (after delivery thereof to the Borrower)
              expires or terminates or (B) funds subject to the escrow
              arrangement under the Refinancing Commitment are released to any
              party other than the Agent for the benefit of itself, the Issuing
              Bank and the Lenders;"

              (D)  The definition of "Loan Documents" set forth in Section 1.01
         of the Credit Agreement is hereby amended in its entirety so as to
         read in full as follows:

                   "'LOAN DOCUMENTS' means this Agreement, the Notes, the Fee
              Letter, the Second Amendment, the Borrower Pledge Agreement
              (including, without limitation, the Amendment to Borrower Pledge
              Agreement delivered pursuant to the Fourth Amendment), each of
              the Guaranties, Security Agreements and other documents delivered
              by the Borrower or any of its Subsidiaries pursuant to Section 6
              of the Second Amendment, the Fourth Amendment, the PFI
              Consideration Pledge

<PAGE>

                                          4

              Agreement (including, without limitation, the Amendment to
              Borrower Security Agreement delivered pursuant to the Fifth
              Amendment), the PFI Consideration Consent Agreement, the Fifth
              Amendment, the Sixth Amendment and any document delivered by the
              Borrower for the benefit of the Lenders, Issuing Bank or Agent in
              connection with the Sierra Subordinated Note, in each case as
              amended, supplemented or otherwise modified from time to time."

              (E)  The definition of "Refinancing Commitment" set forth in
         Section 1.01 of the Credit Agreement (and including, without
         limitation, for purposes of Sections 7, 8 and 9 of the Fifth
         Amendment) is hereby amended in its entirety so as to read in full as
         follows:

                   "'REFINANCING COMMITMENT' means, collectively, one or more
              commitment letters or agreements and, individually, each such
              letter or agreement, that satisfy all of the following
              requirements: (i) each such letter or agreement has been provided
              or entered into by parties (other than the Borrower) satisfactory
              to the Majority Lenders in their sole and absolute discretion;
              (ii) each such letter or agreement has terms that have been
              approved by the Majority Lenders in their sole and absolute
              discretion; and (iii) such letters or agreements collectively
              provide for (A) a commitment to provide financing by one or more
              lenders satisfactory to the Majority Lenders in their sole and
              absolute discretion or (B) funds to be held in escrow and
              disbursed by an escrow agent and on terms in each case
              satisfactory to the Majority Lenders in their sole and absolute
              discretion, which financing and/or funds shall collectively be
              sufficient to enable the Borrower to pay all Obligations in full
              (including, without limitation, replacement and termination of
              any outstanding Letter of Credit) at or before the Effective Time
              (as defined in the Merger Agreement) of the Merger."

              (F)  The definition of "Refinancing Provider" set forth in
         Section 1.01 of the Credit Agreement (and including, without
         limitation, for purposes of Sections 7, 8 and 9 of the Fifth
         Amendment) is hereby amended in its entirety so as to read in full as
         follows:

                   "'REFINANCING PROVIDER' (i) any lender party to a commitment
              to provide financing under any commitment letter or agreement
              comprising the Refinancing Commitment and (ii) any Person acting
              as escrow agent and any Person (other than the Borrower)
              otherwise party to an escrow arrangement arising under the
              Refinancing Commitment."

<PAGE>

                                          5

         (ii) Section 1.01 of the Credit Agreement is hereby amended by the
    addition of the following definitions thereto:

              "SIXTH AMENDMENT" means the Sixth Amendment and Waiver Agreement
         dated as of January 8, 1997 among the Borrower, the Lenders parties
         thereto, the Issuing Bank and the Agent.

              "SIERRA SUBORDINATED NOTE" has the meaning set forth in
         Preliminary Statement 4 of the Sixth Amendment.

              "SIERRA SUBORDINATED NOTE DOCUMENT" has the meaning set forth in
         Section 5 of the Sixth Amendment.

         (iii)     Section 6.02 of the Credit Agreement is hereby amended by
    the addition of a new subsection (q) thereto, to read as follows:

              "(q) MODIFICATIONS TO SIERRA NOTE DOCUMENTS.   Amend, supplement
         or otherwise modify the Sierra Subordinated Note or any other Sierra
         Subordinated Note Document, unless, in any case, both (1) the Borrower
         shall have given the Agent written notice thereof prior to the
         effective date of the proposed amendment, supplement or modification,
         as the case may be, and (2) the Agent shall have notified the Borrower
         prior to such effective date that the Majority Lenders (acting in
         their sole and absolute discretion) have determined that the proposed
         amendment, supplement or modification, as the case may be, would not
         materially and detrimentally affect the rights, remedies, privileges
         or interests of the Agent, Issuing Bank or Lenders under or in respect
         of the Obligations or the Sierra Subordinated Note Documents or this
         Agreement or the other Loan Documents."

         (iv) Subsections (a) and (b) of Section 7 of the Fifth Amendment are
    hereby amended in their entirety so as to read in full as a single
    subsection (a), as follows:

              "(a) The Borrower shall have received or entered into one or more
         commitment letters and agreements that individually and collectively
         satisfy the requirements, of and collectively comprise, the
         Refinancing Commitment; and the Borrower shall have provided copies
         thereof, certified to be true and complete by the Borrower's Chief
         Executive Officer or Chief Financial Officer, to the Agent."

         (v)  Clause (B) of Section 8(e) of the Fifth Amendment is hereby
    amended in its entirety so as to read in full as follows:

<PAGE>

                                          6

              "(B) the expiration or termination of the commitment under the
         Refinancing Commitment or any disbursement of funds under any escrow
         arrangement provided for under the Refinancing Commitment or the
         Borrower's receipt or dispatch of any notice of such termination or
         disbursement;"

         SECTION 2.     PRICING INCREASE ALTERNATIVE WAIVERS AND AMENDMENTS.
(a)   PRICING INCREASE ALTERNATIVE WAIVERS.    The Issuing Bank and the Lenders
hereby waive (i) any occurrence of the Termination Date or Fifth Amendment
Termination Date prior to the Sixth Amendment B Effective Date (as defined in
Section 6 below) resulting solely from the Borrower's failure to satisfy the
conditions of Section 7 of the Fifth Amendment, (ii) any failure of the Borrower
to make any payment that became payable solely as a result of any such
occurrence and (iii) any requirement that the Borrower pay interest at the
default rate under Section 2.07(b) of the Credit Agreement accruing for the
period from December 31, 1996 until the Sixth Amendment B Effective Date on
Obligations that became due and payable solely as a result of any such
occurrence.

         (b)  PRICING INCREASE ALTERNATIVE AMENDMENTS.     (i)   (A)   The
    definition of Applicable Base Rate Margin" set forth in Section 1.01 of the
    Credit Agreement is hereby amended in its entirety so as to read in full as
    follows:

                   "'APPLICABLE BASE RATE MARGIN' means, at all times after
              December 31, 1996, 2.00%."

              (B)  Clause (ii) of the definition of "Fifth Amendment
         Termination Date" set forth in Section 1.01 of the Credit Agreement is
         hereby amended in its entirety so as to read in full as follows:

                   "(ii)     February 17, 1997, if the conditions of Section 7
              of the Fifth Amendment have not been satisfied in full on or
              before such date;"

              (C)  Clause (iii) of the definition of "Fifth Amendment
         Termination Date" set forth in Section 1.01 of the Credit Agreement is
         hereby amended in its entirety so as to read in full as follows:

                   "(iii)    any date on which (A) the commitment under the
              Refinancing Commitment (after delivery thereof to the Borrower)
              expires or terminates or (B) funds subject to the escrow
              arrangement under the Refinancing Commitment are released to any
              party other than the Agent for the benefit of itself, the Issuing
              Bank and the Lenders;"

<PAGE>

                                          7

              (D)  The definition of "Loan Documents" set forth in Section 1.01
         of the Credit Agreement is hereby amended in its entirety so as to
         read in full as follows:

                   "'LOAN DOCUMENTS' means this Agreement, the Notes, the Fee
              Letter, the Second Amendment, the Borrower Pledge Agreement
              (including, without limitation, the Amendment to Borrower Pledge
              Agreement delivered pursuant to the Fourth Amendment), each of
              the Guaranties, Security Agreements and other documents delivered
              by the Borrower or any of its Subsidiaries pursuant to Section 6
              of the Second Amendment, the Fourth Amendment, the PFI
              Consideration Pledge Agreement (including, without limitation,
              the Amendment to Borrower Security Agreement delivered pursuant
              to the Fifth Amendment), the PFI Consideration Consent Agreement,
              the Fifth Amendment and the Sixth Amendment, in each case as
              amended, supplemented or otherwise modified from time to time."

              (E)  The definition of "Refinancing Commitment" set forth in
         Section 1.01 of the Credit Agreement (and including, without
         limitation, for purposes of Sections 7, 8 and 9 of the Fifth
         Amendment) is hereby amended in its entirety so as to read in full as
         follows:

                   "'REFINANCING COMMITMENT' means, collectively, one or more
              commitment letters or agreements and, individually, each such
              letter or agreement, that satisfy all of the following
              requirements: (i) each such letter or agreement has been provided
              or entered into by parties (other than the Borrower) satisfactory
              to the Majority Lenders in their sole and absolute discretion;
              (ii) each such letter or agreement has terms that have been
              approved by the Majority Lenders in their sole and absolute
              discretion; and (iii) such letters or agreements collectively
              provide for (A) a commitment to provide financing by one or more
              lenders satisfactory to the Majority Lenders in their sole and
              absolute discretion or (B) funds to be held in escrow and
              disbursed by an escrow agent and on terms in each case
              satisfactory to the Majority Lenders in their sole and absolute
              discretion, which financing and/or funds shall collectively be
              sufficient to enable the Borrower to pay all Obligations in full
              (including, without limitation, replacement and termination of
              any outstanding Letter of Credit) at or before the Effective Time
              (as defined in the Merger Agreement) of the Merger."

              (F)  The definition of "Refinancing Provider" set forth in
         Section 1.01 of the Credit Agreement (and including, without
         limitation, for purposes

<PAGE>

                                          8

         of Sections 7, 8 and 9 of the Fifth Amendment) is hereby amended in
         its entirety so as to read in full as follows:

                   "'REFINANCING PROVIDER' (i) any lender party to a commitment
              to provide financing under any commitment letter or agreement
              comprising the Refinancing Commitment and (ii) any Person acting
              as escrow agent and any Person (other than the Borrower)
              otherwise party to an escrow arrangement arising under the
              Refinancing Commitment."

         (ii) Section 1.01 of the Credit Agreement is hereby amended by the
    addition of the following definition thereto:

              "SIXTH AMENDMENT" means the Sixth Amendment and Waiver Agreement
         dated as of January 8, 1997 among the Borrower, the Lenders parties
         thereto, the Issuing Bank and the Agent.

         (iii)Section 2.07 (b) of the Credit Agreement is hereby amended in its
    entirety so as to read in full as follows:

              "(b) DEFAULT INTEREST.   Upon the occurrence and during the
         continuance of an Event of Default, the Borrower shall pay interest on
         the unpaid principal amount of each Advance owing to each Lender and,
         to the fullest extent permitted by law, on the unpaid amount of all
         interest, fees and other amounts payable hereunder and under the other
         Loan Documents, payable in arrears on demand by the Agent and on the
         date such amount shall be paid in full, at a rate per annum equal at
         all times to 4% per annum above the Base Rate in effect from time to
         time (computed on the basis of a year of 360 days for the actual
         number of days (including the first day but excluding the last day)
         occurring during the period for which such interest is payable)."

         (iv) Subsections (a) and (b) of Section 7 of the Fifth Amendment are
    hereby amended in their entirety so as to read in full as a single
    subsection (a), as follows:

              "(a) The Borrower shall have received or entered into one or more
         commitment letters and agreements that individually and collectively
         satisfy the requirements, of and collectively comprise, the
         Refinancing Commitment; and the Borrower shall have provided copies
         thereof, certified to be true and complete by the Borrower's Chief
         Executive Officer or Chief Financial Officer, to the Agent."

         (v)  Clause (B) of Section 8(e) of the Fifth Amendment is hereby
    amended in its entirety so as to read in full as follows:

<PAGE>

                                          9

              "(B) the expiration or termination of the commitment under the
         Refinancing Commitment or any disbursement of funds under any escrow
         arrangement provided for under the Refinancing Commitment or the
         Borrower's receipt or dispatch of any notice of such termination or
         disbursement;"

         (vi) Section 8(f) of Fifth Amendment is hereby amended in its entirety
    so as to read in full as follows:

              "(f) TERMINATION FEE. In the event that the Obligations have not
         been or are not paid in full (including, without limitation,
         replacement and termination of any outstanding Letter of Credit) on or
         before the Fifth Amendment Termination Date, then on the Fifth
         Amendment Termination Date, the Borrower shall pay the to the Agent,
         in immediately available funds for the ratable account of the Lenders,
         a fee in the amount of 2.00% of the aggregate amount of the Advances
         and Letter of Credit Liability outstanding on the Fifth Amendment
         Termination Date (after giving effect to any payment of such Advances
         or reduction in Letter of Credit Liability made on such date).
         Without limiting any provision of any Loan Document, such fee shall be
         payable in addition to interest at the default rate under the Credit
         Agreement and all other amounts payable under the Loan Documents."

         SECTION 3.  REPRESENTATIONS AND WARRANTIES.  The Borrower hereby
represents and warrants as follows:

         (a)  All representations and warranties of the Borrower contained in
    the Credit Agreement, both before and after giving effect to Sections 1 and
    2 hereof, are true in all material respects (except for any such
    representation or warranty (or portion thereof) that is qualified by
    reference to a specific materiality standard, in which case such
    representation or warranty is true in all respects).

         (b)  Without limiting the representations and warranties made in
    subsection (a) above or in the Credit Agreement, no authorization, consent,
    approval or other action by, and no notice to or filing with, any HMO
    Regulator or Insurance Regulator is required for, and no HMO Event,
    Insurance Event or violation of the HMO Regulations or Insurance
    Regulations would result from, the due execution, delivery or performance
    by the Borrower or any Loan Party of this Amendment or any of the Loan
    Documents and other documents to be delivered in connection herewith.

         SECTION 4.  REFERENCE TO AND EFFECT ON LOAN DOCUMENTS.   (a)   On and
after the date hereof, each reference in the Credit Agreement to "this
Agreement", "hereunder", "hereof", "herein", or words of like import referring
to the Credit Agreement,

<PAGE>

                                          10

and each reference to the Credit Agreement in the other Loan Documents, shall
mean and be a reference to the Credit Agreement as amended hereby.

         (b)  Except as specifically amended under Section 1(b) or 2(b) hereof,
as the case may be, or modified by the waiver under Section 1(a) or 2(a) hereof,
as the case may be, each of the Credit Agreement and each other Loan Document
shall remain in full force and effect and is hereby ratified and confirmed.

         (c)  The Borrower acknowledges and agrees that, except to the extent
specifically amended under Section 1(b) or 2(b) hereof, as the case may be, or
modified by the waiver under Section 1(a) or 2(a) hereof, as  the case may be,
it is obligated to comply with each and every term, covenant, agreement and
condition applicable to it under the Credit Agreement or the other Loan
Documents.  The execution, delivery and effectiveness of this Amendment shall
not otherwise operate as a waiver of any right, remedy or privilege of any
Lender, the Issuing Bank or the Agent under the Credit Agreement or any other
Loan Document, any and all of which rights, remedies and privileges are
reserved.

         SECTION 5.  CONDITIONS OF EFFECTIVENESS OF PRINCIPAL PAYDOWN
ALTERNATIVE UNDER SECTION 1.  Section 1 of this Amendment shall become effective
(to the exclusion of Section 2 hereof), subject to the satisfaction on or before
January 10, 1997 of the following conditions precedent, as of the date, if any
(the "Sixth Amendment A Effective Date"), when all such conditions shall first
have been so satisfied:

         (a)  The Agent shall have received counterparts of this Amendment duly
    executed by the Borrower, the Issuing Bank and each Lender and a
    counterpart of the Consent of Guarantor attached hereto duly executed by
    the Guarantor.

         (b)  The Agent shall have received on or before the Sixth Amendment A
    Effective Date the following, each dated such date (unless otherwise
    specified), in form and substance satisfactory to the Agent, the Issuing
    Bank and the Majority Lenders (unless otherwise specified) and in
    sufficient copies for the Agent, Issuing Bank and each Lender:

              (i)  A certificate, duly executed by the Borrower's Chief
         Executive Officer or Chief Financial Officer, certifying that (i) on
         such date, after giving effect to Section 1 hereof, no Default or
         Event of Default has occurred and is continuing (ii) on such date,
         after giving effect to Section 1 hereof, no event or circumstance has
         occurred that will cause the occurrence of the Fifth Amendment
         Termination Date and (iii) the representations and warranties set
         forth in Section 3 hereof are true on and as of such date.

<PAGE>

                                          11

              (ii) Certified copies of the resolutions of the Board of
         Directors of the Borrower approving this Amendment, and of all
         documents evidencing other necessary corporate action and governmental
         and other third party approvals and consents, if any, with respect
         each such Loan Document.

              (iii)A certificate of the Secretary or an Assistant Secretary of
         the Borrower certifying the names and true signatures of the officers
         of the Borrower authorized to sign this Amendment.

              (iv) A legal opinion from Greenberg, Traurig, Hoffman, Lipoff,
         Rosen & Quintal, P.A., counsel to the Borrower, as to this Amendment
         and the Credit Agreement, as amended hereby, in form and substance
         satisfactory to the Agent.

              (v)  A legal opinion from Morgan, Lewis & Bockius, counsel to
         Sierra, in form and substance satisfactory to the Agent, as to the
         authorization, execution and delivery by, and enforceability against,
         Sierra of Sierra Subordinated Note Documents and as to such other
         matters as the Agent may reasonably request.

         (c)  The Agent shall have received copies, certified by the Borrower's
    Chief Executive Officer or Chief Financial Officer to be true and complete
    as of the Sixth Amendment A Effective Date, of the Sierra Subordinated Note
    and each document delivered in connection therewith, including, without
    limitation a subordination agreement for the benefit of the Lenders, the
    Issuing Bank and the Lenders and each document providing for the creation
    or perfection of any lien to secure the Sierra Subordinated Note (all such
    documents, together with the Sierra Subordinated Note, as the same may be
    amended, supplemented or otherwise modified and in effect from time to
    time, being the "Sierra Subordinated Note Documents"), and the Agent shall
    have advised the Borrower that the terms of each Sierra Subordinated Note
    Document are satisfactory to all of the Lenders and the Issuing Bank, in
    their sole and absolute discretion.

         (d)  The Borrower shall have paid to the Agent, in immediately
    available funds (i) the sum of $16,750,000, as the proceeds of the Sierra
    Subordinated Note, for application toward the installment of principal that
    became due on December 31, 1996 under Section 2.10(a)(i) of the Credit
    Agreement, plus (ii) the unpaid interest accrued on such principal.

         (e)  The Borrower shall have paid all amounts accrued and payable
    under Section 9.04 of the Credit Agreement to the extent that request for
    such payment has been made to the Borrower.

<PAGE>

                                          12

         (f)  Section 2 hereof shall not have become effective.

         SECTION 6.  CONDITIONS OF EFFECTIVENESS OF PRICING INCREASE
ALTERNATIVE UNDER SECTION 2.  Section 2 of this Amendment shall become effective
(to the exclusion of Section 1 hereof), subject to the satisfaction on or before
January 10, 1997 of the following conditions precedent, as of the date, if any
(the "Sixth Amendment B Effective Date"), when all such conditions shall first
have been so satisfied:

         (a)  The Agent shall have received counterparts of this Amendment duly
    executed by the Borrower, the Issuing Bank and each Lender and a
    counterpart of the Consent of Guarantor attached hereto duly executed by
    the Guarantor.

         (b)  The Agent shall have received on or before the Sixth Amendment B
    Effective Date the following, each dated such date (unless otherwise
    specified), in form and substance satisfactory to the Agent, the Issuing
    Bank and the Majority Lenders (unless otherwise specified) and in
    sufficient copies for the Agent, Issuing Bank and each Lender:

              (i)  A certificate, duly executed by the Borrower's Chief
         Executive Officer or Chief Financial Officer, certifying that (i) on
         such date, after giving effect to Section 2 hereof, no Default or
         Event of Default has occurred and is continuing (ii) on such date,
         after giving effect to Section 2 hereof, no event or circumstance has
         occurred that will cause the occurrence of the Fifth Amendment
         Termination Date and (iii) the representations and warranties set
         forth in Section 3 hereof are true on and as of such date.

              (ii) Certified copies of the resolutions of the Board of
         Directors of the Borrower approving this Amendment, and of all
         documents evidencing other necessary corporate action and governmental
         and other third party approvals and consents, if any, with respect
         each such Loan Document.

              (iii)A certificate of the Secretary or an Assistant Secretary of
         the Borrower certifying the names and true signatures of the officers
         of the Borrower authorized to sign this Amendment.

              (iv) A legal opinion from Greenberg, Traurig, Hoffman, Lipoff,
         Rosen & Quintal, P.A., counsel to the Borrower, as to this Amendment
         and the Credit Agreement, as amended hereby, in form and substance
         satisfactory to the Agent.

         (c)  The Borrower shall have paid to the Agent, in immediately
    available funds for the rateable account of the Lenders, a fee in the
    amount of 0.50% of the

<PAGE>

                                          13

    aggregate amount of the Advances and Letter of Credit Liability outstanding
    on the date hereof.

         (d)  The Borrower shall have paid all amounts accrued and payable
    under Section 9.04 of the Credit Agreement to the extent that request for
    such payment has been made to the Borrower.

         (e)  Section 1 hereof shall not have become effective.

         SECTION 7.     CONVERSION TO BASE RATE ADVANCES.   The Borrower agrees
that no Advance may be Converted into or continued as a Eurodollar Advance after
the date hereof, notwithstanding any provision of the Credit Agreement to the
contrary.

         SECTION 8.  COUNTERPARTS.  This Amendment may be executed in any
number of counterparts and by different parties hereto on separate counterparts,
each of which, when so executed and delivered, shall be an original, but all
such counterparts shall together constitute one and the same agreement.

         SECTION 9.  GOVERNING LAW.  THIS AMENDMENT SHALL BE GOVERNED BY, AND
CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

<PAGE>

                                          14

         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to
be duly executed and delivered by their respective officers thereunto duly
authorized, as of the date first above written.

                             THE BORROWER:

                             PHYSICIAN CORPORATION OF AMERICA


                             By:
                                -----------------------------
                                  Name:
                                  Title:


                             THE LENDERS AND ISSUING BANK:


                             CITIBANK, N.A., as Lender and as Issuing Bank


                             By:
                                ------------------------------------------
                                  Name:
                                  Title:


                             FIRST UNION NATIONAL BANK OF NORTH CAROLINA


                             By:
                                ------------------------------------------
                                  Name:
                                  Title:


                             NATIONSBANK OF TENNESSEE


                             By:
                                ------------------------------------------
                                  Name:
                                  Title:


<PAGE>

                                          15

                             BOATMEN'S NATIONAL BANK (formerly known as
                             Boatmen's First National Bank of Kansas City)


                             By:
                                ------------------------------------------
                                  Name:
                                  Title:


                             SUNTRUST BANK, MIAMI, N.A.


                             By:
                                ------------------------------------------
                                  Name:
                                  Title:


                             THE BANK OF NOVA SCOTIA


                             By:
                                ------------------------------------------
                                  Name:
                                  Title:
 <PAGE>

                                 CONSENT OF GUARANTOR


         The undersigned, as Guarantor under that certain Guaranty dated as of
March 29, 1996 (the "Guaranty") made in favor of the lenders parties to the
Revolving Credit Agreement referred to in the foregoing Sixth Amendment and
Waiver Agreement, the Issuing Bank and the Agent (in each case as defined in
such Revolving Credit Agreement), hereby consents to such Sixth Amendment and
Waiver Agreement (and to all prior amendments, waivers, consents and other
modifications to or under such Revolving Credit Agreement) and confirms and
agrees that notwithstanding such Sixth Amendment and Waiver Agreement (or any
prior such amendment, waiver, consent or other modification) the Guaranty is,
and shall continue to be, in full force and effect and is hereby ratified and
confirmed in all respects.

                                  PCA SOLUTIONS, INC.



                                  By
                                     -----------------------------
                                         Name:
                                         Title: