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                                                                   Exhibit 10.5

                       FIRST AMENDMENT TO CREDIT AGREEMENT

     THIS FIRST AMENDMENT TO CREDIT AGREEMENT (this "AMENDMENT"), dated as of
November 7, 2003, is by and among MEDEX, INC., an Ohio corporation (the
"BORROWER"), MEDVEST HOLDINGS CORPORATION (the "PARENT"), those Domestic
Subsidiaries of the Borrower identified as a "Guarantor" on the signature pages
hereto (together with the Parent, individually a "GUARANTOR" and collectively
the "GUARANTORS"), the Lenders party hereto and WACHOVIA BANK, NATIONAL
ASSOCIATION, as administrative agent (in such capacity, the "ADMINISTRATIVE
AGENT").

                               W I T N E S S E T H

     WHEREAS, the Borrower, the Guarantors, the Lenders party thereto, and the
Administrative Agent have entered into that certain Credit Agreement dated as of
May 21, 2003 (as amended, modified, supplemented or restated from time to time,
the "CREDIT AGREEMENT"; capitalized terms used herein shall have the meanings
ascribed thereto in the Credit Agreement);

     WHEREAS, the Borrower has requested certain amendments to the Credit
Agreement; and

     WHEREAS, the Lenders have agreed to such amendments subject to the terms
and conditions set forth herein.

     NOW, THEREFORE, in consideration of the agreements hereinafter set forth,
and for other good and valuable consideration, the receipt and adequacy of which
are hereby acknowledged, the parties hereto agree as follows:


                                    ARTICLE I
                         AMENDMENTS TO CREDIT AGREEMENT

     1.1 AMENDMENT TO PRICING GRID. The pricing grid set forth in the definition
of "Applicable Percentage" in Section 1.1 of the Credit Agreement is hereby
amended and restated in its entirety to read as follows:

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<Table>
<Caption>
-----------------------------------------------------------------------------------------------------------------------------
                                                         LIBOR Rate
                                     Alternate           Margin for            Alternate
                                     Base Rate       Revolving Loans and       Base Rate          LIBOR Rate
                 Leverage            Margin for           Letter of            Margin for         Margin for      Commitment
    Level         Ratio           Revolving Loans        Credit Fee            Term Loans         Term Loans          Fee
-----------------------------------------------------------------------------------------------------------------------------
    <S>    <C>                    <C>                <C>                       <C>                <C>             <C>
      I       => 4.50 to 1.0           2.75%                3.75%                  2.00%              3.00%           .50%
-----------------------------------------------------------------------------------------------------------------------------
     II     => 4.00 to 1.0 but         2.50%                3.50%                  2.00%              3.00%           .50%
              < 4.50 to 1.0
-----------------------------------------------------------------------------------------------------------------------------
     III    => 3.50 to 1.0 but         2.25%                3.25%                  2.00%              3.00%           .50%
              < 4.00 to 1.0
-----------------------------------------------------------------------------------------------------------------------------
     IV     => 3.00 to 1.0 but         2.00%                3.00%                  1.75%              2.75%           .50%
              < 3.50 to 1.0
-----------------------------------------------------------------------------------------------------------------------------
      V       < 3.00 to 1.0            1.75%                2.75%                  1.75%              2.75%           .50%
-----------------------------------------------------------------------------------------------------------------------------
</Table>

     The Credit Parties and the Lenders acknowledge and agree that the foregoing
modifications to the pricing grid will become effective on the First Amendment
Effective Date and the amended interest rate levels set forth in such pricing
grid shall apply to all Loans outstanding as of such date as well as any Loan
made after such date.


                                   ARTICLE II
                           CONDITIONS TO EFFECTIVENESS

     2.1 CLOSING CONDITIONS.

           This Amendment shall become effective as of the date hereof (the
"FIRST AMENDMENT EFFECTIVE DATE") upon satisfaction of the following conditions
(in form and substance reasonably acceptable to the Administrative Agent):

          (a) EXECUTED AMENDMENT. Receipt by the Administrative Agent of a copy
     of this Amendment duly executed by each of the Credit Parties and each of
     the Lenders.

          (b) RESOLUTIONS. Receipt by the Administrative Agent of copies of
     resolutions of the Board of Directors of each of the Credit Parties
     approving and adopting this Amendment, the transactions contemplated herein
     and authorizing execution and delivery hereof, certified by a secretary or
     assistant secretary of such Credit Party to be true and correct and in
     force and effect as of the date hereof.

          (c) INCUMBENCY CERTIFICATE. Receipt by the Administrative Agent of an
     incumbency certificate with respect to each of the Credit Parties.


                                       2
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          (d) LEGAL OPINIONS OF COUNSEL. The Administrative Agent shall have
     received opinions of legal counsel for the Credit Parties, dated the First
     Amendment Effective Date and addressed to the Administrative Agent and the
     Lenders, which opinions shall provide, among other things, that the
     execution and delivery of the Amendment by the Credit Parties and the
     consummation of the transactions contemplated thereby will not violate the
     corporate instruments and material agreements of the Credit Parties, and
     shall otherwise be in form and substance acceptable to the Administrative
     Agent and the Lenders.

          (e) FEES. Receipt by the Administrative Agent of all fees and expenses
     of the Administrative Agent in connection with the preparation, execution
     and delivery of this Amendment, including, without limitation, the fees and
     expenses of Moore & Van Allen PLLC.


                                   ARTICLE III
                                  MISCELLANEOUS

     3.1 AMENDED TERMS. All references to the Credit Agreement in each of the
Credit Documents shall hereafter mean the Credit Agreement as amended by this
Amendment. Except as specifically amended hereby or otherwise agreed, the Credit
Agreement is hereby ratified and confirmed and shall remain in full force and
effect according to its terms.

     3.2 REPRESENTATIONS AND WARRANTIES OF CREDIT PARTIES. Each of the Credit
Parties represents and warrants as follows as of the date hereof:

          (a) It has taken all necessary action to authorize the execution,
     delivery and performance of this Amendment.

          (b) This Amendment has been duly executed and delivered by such Person
     and constitutes such Person's legal, valid and binding obligations,
     enforceable in accordance with its terms, except as such enforceability may
     be subject to (i) bankruptcy, insolvency, reorganization, fraudulent
     conveyance or transfer, moratorium or similar laws affecting creditors'
     rights generally and (ii) general principles of equity (regardless of
     whether such enforceability is considered in a proceeding at law or in
     equity).

          (c) No consent, approval, authorization or order of, or filing,
     registration or qualification with, any Governmental Authority or third
     party is required in connection with the execution, delivery or performance
     by such Person of this Amendment.

          (d) The representations and warranties set forth in Article III of the
     Credit Agreement are true and correct in all material respects as of the
     date hereof (except for those which expressly relate to an earlier date).


                                       3
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     3.3 ACKNOWLEDGMENT OF GUARANTORS. The Guarantors acknowledge and consent to
all of the terms and conditions of this Amendment and agree that this Amendment
and all documents executed in connection herewith do not operate to reduce or
discharge the Guarantors' obligations under the Credit Documents.

     3.4 CREDIT DOCUMENT. This Amendment shall constitute a Credit Document
under the terms of the Credit Agreement.

     3.5 ENTIRETY. This Amendment and the other Credit Documents embody the
entire agreement between the parties hereto and supersede all prior agreements
and understandings, oral or written, if any, relating to the subject matter
hereof.

     3.6 COUNTERPARTS; TELECOPY. This Amendment may be executed in any number of
counterparts, each of which when so executed and delivered shall be an original,
but all of which shall constitute one and the same instrument. Delivery of an
executed counterpart to this Amendment by telecopy shall be effective as an
original and shall constitute a representation that an original will be
delivered.

     3.7 GENERAL RELEASE. In consideration of the Lenders entering into this
Amendment, the Credit Parties hereby release the Administrative Agent, the
Lenders, and the Administrative Agent's and the Lenders' respective officers,
employees, representatives, agents, counsel and directors from any and all
actions, causes of action, claims, demands, damages and liabilities of whatever
kind or nature, in law or in equity, now known or unknown, suspected or
unsuspected to the extent that any of the foregoing arises from any action or
failure to act under the Credit Agreement on or prior to the date hereof,
except, with respect to any such person being released hereby, any actions,
causes of action, claims, demands, damages and liabilities arising out of such
person's gross negligence, bad faith or willful misconduct.

     3.8 GOVERNING LAW. THIS AMENDMENT AND THE RIGHTS AND OBLIGATIONS OF THE
PARTIES UNDER THIS AMENDMENT SHALL BE GOVERNED BY, AND CONSTRUED AND INTERPRETED
IN ACCORDANCE WITH, THE LAW OF THE STATE OF NEW YORK. EACH OF THE CREDIT PARTIES
AGREES THAT SECTIONS 5-1401 AND 5-1402 OF THE GENERAL OBLIGATIONS LAW OF THE
STATE OF NEW YORK SHALL APPLY TO THIS AMENDMENT AND THE OTHER CREDIT DOCUMENTS.

     3.9 CONSENT TO JURISDICTION; SERVICE OF PROCESS; WAIVER OF JURY TRIAL. The
jurisdiction, services of process and waiver of jury trial provisions set forth
in Sections 9.14 and 9.17 of the Credit Agreement are hereby incorporated by
reference, MUTATIS MUTANDIS.


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     IN WITNESS WHEREOF the Borrower, the Guarantors, the Lenders, and the
Administrative Agent have caused this Amendment to be duly executed on the date
first above written.

BORROWER:                      MEDEX, INC.,
--------                       an Ohio corporation

                               By:      /s/ Michael I. Dobrovic
                                  -----------------------------------
                               Name: Michael I. Dobrovic
                               Title: CFO


PARENT AND OTHER
GUARANTORS:                    MEDVEST HOLDINGS CORPORATION,
----------                     an Ohio corporation
                               MEDEX MEDICAL, INC.,
                               an Ohio corporation
                               MEDEX CARDIO-PULMONARY, INC.,
                               an Ohio corporation


                               By:      /s/ Michael I. Dobrovic
                                  -----------------------------------
                               Name: Michael I. Dobrovic
                               Title: CFO
                                      of each of the foregoing


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ADMINISTRATIVE AGENT:
                               WACHOVIA BANK, NATIONAL ASSOCIATION,
                               as Administrative Agent and as an Existing Lender


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

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EXISTING LENDERS:


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