FOURTH AMENDMENT

Exhibit 10.1

FOURTH AMENDMENT

     This Fourth Amendment (this “Amendment”) is entered into as of June ___, 2008, by and among KENDLE INTERNATIONAL INC., an Ohio corporation (the “Borrower”), the Guarantors listed on the signature pages hereof, the Lenders signatory hereto, and UBS AG, STAMFORD BRANCH, as Administrative Agent for the Lenders (in such capacity, “Administrative Agent”).

RECITALS

     WHEREAS, the Borrower, the Guarantors, the Lenders, the Administrative Agent, UBS SECURITIES LLC, as sole lead arranger and sole bookrunner, UBS AG, STAMFORD BRANCH, as issuing bank and collateral agent, UBS LOAN FINANCE LLC, as swingline lender, JPMORGAN CHASE BANK, N.A., as syndication agent, and KEYBANK NATIONAL ASSOCIATION, LASALLE BANK NATIONAL ASSOCIATION, and NATIONAL CITY BANK, as co-documentation agents, are parties to that certain Credit Agreement dated as of August 16, 2006, as amended by that certain First Amendment to Credit Agreement dated as of December 11, 2006, as amended by that certain Second Amendment to Credit Agreement dated as of March 30, 2007 and as amended by that certain Third Amendment to Credit Agreement dated as of December 18, 2007 (the “Credit Agreement”) (capitalized terms used herein without definition have the meanings ascribed to such terms in the Credit Agreement);

     WHEREAS, the Borrower has requested certain changes to Sections 1.01, 2.10, 5.01, 6.01 and 6.10(c) of the Credit Agreement; and

     WHEREAS, the Administrative Agent and the Required Lenders have agreed to amend the above-mentioned sections of the Credit Agreement on the terms and subject to the conditions set forth herein.

     NOW THEREFORE, in consideration of the premises and the mutual covenants herein contained, the parties hereto hereby agree as follows:

          Section 1. Section References. Unless otherwise expressly stated herein, all Section references herein shall refer to Sections of the Credit Agreement.

          Section 2. Amendment to Section 1.01 (Defined Terms). Section 1.01 of the Credit Agreement is hereby amended by deleting in their entirety the definitions of “Excess Cash Flow” and “Excess Cash Flow Period”.

          Section 3. Amendment to Section 2.10 (Optional and Mandatory Prepayments of Loans).

               (a) Each of Section 2.10(c), (d), (e), (f) and (g) of the Credit Agreement is hereby deleted in its entirety and each is replaced with “Reserved”.

               (b) Section 2.10(h) of the Credit Agreement is hereby deleted in its entirety and replaced with the following:

“(h) Application of Prepayments. Prior to any optional or mandatory prepayment hereunder, Borrower shall select the Borrowing or Borrowings to be prepaid and shall specify such selection in the notice of such prepayment pursuant to Section 2.10(i), subject to the provisions of this Section 2.10(h). Amounts to be applied pursuant to this Section 2.10 to the prepayment of Revolving Loans shall be applied first to reduce outstanding ABR Revolving Loans. Any amounts remaining after each such application shall be applied to prepay Eurodollar Revolving Loans. Notwithstanding the foregoing, if the amount of any prepayment of Loans required under this Section 2.10 shall be in excess of the amount of the ABR Loans at the time outstanding (an “Excess Amount”), only the portion of the amount of such prepayment as is equal to the amount of such outstanding ABR Loans shall be immediately prepaid and, at the election of Borrower, the Excess Amount shall be either (A) deposited in an escrow account on terms satisfactory to the Collateral Agent and applied to the prepayment of Eurodollar Loans on the last day of the then next-expiring Interest Period for Eurodollar Loans; provided that (i) interest in respect of such Excess Amount shall continue to accrue thereon at the rate provided hereunder for the Loans which such Excess Amount is intended to repay until such Excess Amount shall have been used in full to repay such Loans and (ii) at any time while an Event of Default has occurred and is continuing, the Administrative Agent may, and upon written direction from the Required Lenders shall, apply any or all proceeds then on deposit to the payment of such Loans in an amount equal to such Excess Amount or (B) prepaid immediately, together with any amounts owing to the Lenders under Section 2.13.”

          Section 4. Amendment to Section 5.01(a) (Financial Statements, Reports, etc. —Annual Reports). Section 5.01(a) of the Credit Agreement is hereby amended by deleting “and budgeted amounts”.

          Section 5. Amendment to Section 5.01(b) (Financial Statements, Reports, etc. —Quarterly Reports). Section 5.01(b) of the Credit Agreement is hereby amended by deleting “and budgeted amounts”.

          Section 6. Amendment to Section 5.01(c) (Financial Statements, Reports, etc.—Financial Officer’s Certificate). Section 5.01(c) of the Credit Agreement is hereby amended by deleting “and, concurrently with any delivery of financial

statements under Section 5.01(a) above, setting forth Borrower’s calculation of Excess Cash Flow”.

          Section 7. Amendment to Section 6.01 (Indebtedness).

               (a) Section 6.01(k) of the Credit Agreement is hereby amended by deleting “and” at the end of such section.

               (b) Section 6.01(l) of the Credit Agreement is hereby amended by replacing the period at the end of such section with “; and”.

               (c) Section 6.01 of the Credit Agreement is hereby amended by adding the following as Section 6.01(m): “(m) solely in connection with a Permitted Acquisition, Indebtedness consisting of obligations for deferred purchase price, “earn-outs” or other agreements to make any payment the amount of which is, or the terms of payment of which are, in any respect subject to or contingent upon the revenues, income, cash flow or profits (or the like) of any person or business, in an amount not in excess of $25.0 million at any time outstanding for all Permitted Acquisitions; provided however that, for the avoidance of doubt, nothing in this Section 6.01(m) shall be deemed to increase the maximum amount of Acquisition Consideration permitted under clause (ix) of the definition of “Permitted Acquisition”.”

          Section 8. Amendment to Section 6.10(c) (Limitation on Capital Expenditures). Section 6.10(c) of the Credit Agreement is hereby amended by adding the following sentence at the end of such section: “For purposes of this Section 6.10(c), Capital Expenditures shall not include any Capital Expenditures of up to $25.0 million in the aggregate to the extent funded directly or indirectly by an unaffiliated landlord pursuant to a leasehold improvement allowance or tenant improvement allowance under any Lease of Real Property (including Capital Expenditures to the extent funded by the landlord pursuant to the leasehold improvement allowance in the Borrower’s lease agreement entered into prior to June 15, 2008 with respect to its offices at 441 Vine Street, Cincinnati, Ohio 45202).”

          Section 9. Conditions Precedent. The effectiveness of this Amendment is subject to the satisfaction of each of the following conditions precedent:

               (a) The Administrative Agent shall have received all of the following, in form and substance satisfactory to the Administrative Agent:

                    (i) Amendment Documents. This Amendment, duly executed by the Borrower and the Guarantors (the “Amendment Documents”);

                    (ii) Consent of Required Lenders. The written consent of the Required Lenders to this Amendment; and

                    (iii) Additional Information. Such additional documents, instruments and information as the Administrative Agent may reasonably request to effect the transactions contemplated hereby.

               (b) The representations and warranties contained herein and in the Credit Agreement shall be true and correct in all material respects as of the date hereof as if made on the date hereof (except for those which by their terms specifically refer to an earlier date, in which case such representations and warranties shall be true and correct in all material respects as of such earlier date).

               (c) All corporate proceedings taken in connection with the transactions contemplated by this Amendment and all other agreements, documents and instruments executed or delivered pursuant hereto, and all legal matters incident thereto, shall be reasonably satisfactory to the Administrative Agent.

               (d) No Default or Event of Default shall have occurred and be continuing, after giving effect to this Amendment.

          Section 10. Representations and Warranties. The Borrower hereby represents and warrants to the Administrative Agent and the Lenders that, as of the date of and after giving effect to this Amendment, (a) the execution, delivery and performance of this Amendment and any and all other Amendment Documents executed and/or delivered in connection herewith have been authorized by all requisite corporate action on the part of the Borrower and will not violate the Borrower’s certificate of incorporation or bylaws, (b) all representations and warranties set forth in the Credit Agreement and in any other Loan Document are true and correct in all material respects as if made again on and as of such date (except those, if any, which by their terms specifically relate only to an earlier date, in which case such representations and warranties are true and correct in all material respects as of such earlier date), and (c) no Default or Event of Default has occurred and is continuing.

          Section 11. Survival of Representations and Warranties. All representations and warranties made in this Amendment or any other Loan Document shall survive the execution and delivery of this Amendment and the other Loan Documents, and no investigation by the Administrative Agent or the Lenders, or any closing, shall affect the representations and warranties or the right of the Administrative Agent and the Lenders to rely upon them.

          Section 12. Certain Waivers. Each of the Borrower and the Guarantors hereby agrees that neither the Administrative Agent nor any Lender shall be liable under a claim of, and hereby waives any claim against the Administrative Agent and the Lenders based on, lender liability (including, but not limited to, liability for breach of the implied covenant of good faith and fair dealing, fraud, negligence, conversion, misrepresentation, duress, control and interference, infliction of emotional distress and defamation and breach of fiduciary duties) as a result of the amendments contained herein and any discussions or actions taken or not taken by the Administrative Agent or the Lenders on or before the date hereof or the discussions conducted in connection

therewith, or any course of action taken by the Administrative Agent or any Lender in response thereto or arising therefrom; provided, that the foregoing waiver shall not include the waiver of any claims which are based on the gross negligence or willful misconduct of the Administrative Agent or any Lender or any of their respective agents. This section shall survive the execution and delivery of this Amendment and the other Loan Documents and the termination of the Credit Agreement.

          Section 13. Reference to Agreement. Each of the Loan Documents, including the Credit Agreement, and any and all other agreements, documents or instruments now or hereafter executed and/or delivered pursuant to the terms hereof or pursuant to the terms of the Credit Agreement as amended hereby, are hereby amended so that any reference in such Loan Documents to the Credit Agreement, whether direct or indirect, shall mean a reference to the Credit Agreement as amended hereby.

          Section 14. Costs and Expenses. The Borrower shall pay on demand all reasonable out-of-pocket costs and expenses of the Administrative Agent (including the reasonable fees, costs and expenses of counsel to the Administrative Agent) incurred in connection with the preparation, execution and delivery of this Amendment.

          Section 15. Governing Law. THIS AMENDMENT SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

          Section 16. Headings. Section headings in this Amendment are included herein for convenience of reference only and shall not constitute a part of this Amendment for any other purposes.

          Section 17. Execution. This Amendment 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 agreement. Delivery of an executed counterpart of a signature page to this Amendment by telecopier shall be effective as delivery of a manually executed counterpart of this Amendment.

          Section 18. Limited Effect. This Amendment relates only to the specific matters covered herein, shall not be considered to be a waiver of any rights any Lender may have under the Credit Agreement (other than as expressly set forth herein), and shall not be considered to create a course of dealing or to otherwise obligate any Lender to execute similar amendments under the same or similar circumstances in the future.

          Section 19. Ratification By Guarantors. Each Guarantor hereby agrees to this Amendment, and each Guarantor acknowledges that such Guarantor’s Guarantee shall remain in full force and effect without modification thereto.

[signature pages follow]

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