SUBSIDIARY GUARANTY

Exhibit 4.6

EXECUTION COPY

SUBSIDIARY GUARANTY

This SUBSIDIARY GUARANTY is entered into as of April 2, 2012, by and among THE UNDERSIGNED (each a “Guarantor”, and, together with any Additional Guarantors (as hereinafter defined), collectively the “Guarantors”) in favor of and for the benefit of Credit Suisse AG, Cayman Islands Branch, as agent for and representative of (in such capacity herein called “Guarantied Party”) the financial institutions party to the Credit Agreement (as hereinafter defined) (the “Lenders”) referred to below, and, subject to subsection 3.12, for the benefit of the other Beneficiaries (as hereinafter defined).

RECITALS

A. Aristotle Holding, Inc. (to be renamed Express Scripts Holding Company), a Delaware corporation, has entered into that certain Credit Agreement dated as of August 29, 2011, with Express Scripts, Inc., a Delaware corporation, the financial institutions from time to time party thereto as Lenders and Credit Suisse AG, Cayman Islands Branch, as Administrative Agent (as amended, supplemented or otherwise modified from time to time, the “Credit Agreement”; capitalized terms defined therein and not otherwise defined herein being used herein as therein defined).

B. Each Guarantor is an Affiliate of Company and will derive substantial benefits from the extension of credit to Company pursuant to the Credit Agreement.

C. It is a condition precedent to the making of the Loans under the Credit Agreement that Company’s obligations thereunder be guarantied by Guarantors.

D. Guarantors are willing irrevocably and unconditionally to guaranty such obligations of Company.

NOW, THEREFORE, based upon the foregoing and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, and in order to induce Lenders and Guarantied Party to enter into the Credit Agreement and to make Loans and other extensions of credit thereunder, Guarantors hereby agree as follows:

SECTION 1. DEFINITIONS

1.1 Certain Defined Terms. As used in this Guaranty, the following terms shall have the following meanings unless the context otherwise requires:

“Beneficiaries” means Guarantied Party and Lenders.

“Guarantied Obligations” has the meaning assigned to that term in subsection 2.1.

“Guaranty” means this Subsidiary Guaranty, as it may be amended, supplemented or otherwise modified from time to time.

“payment in full”, “paid in full” or any similar term means payment in full of the Guarantied Obligations, including all principal, interest, costs, fees and expenses (including reasonable legal fees and expenses) of Beneficiaries as required under the Loan Documents.

1.2 Interpretation.

(a) References to “Sections” and “subsections” shall be to Sections and subsections, respectively, of this Guaranty unless otherwise specifically provided.

(b) In the event of any conflict or inconsistency between the terms, conditions and provisions of this Guaranty and the terms, conditions and provisions of the Credit Agreement, the terms, conditions and provisions of this Guaranty shall prevail.

SECTION 2. THE GUARANTY

2.1 Guaranty of the Guarantied Obligations. Subject to the provisions of subsection 2.2(a), Guarantors jointly and severally hereby irrevocably and unconditionally guaranty, as primary obligors and not merely as sureties, the due and punctual payment in full of all Guarantied Obligations when the same shall become due, whether at stated maturity, by required prepayment, declaration, acceleration, demand or otherwise (including amounts that would become due but for the operation of the automatic stay under Section 362(a) of the Bankruptcy Code, 11 U.S.C. § 362(a)). The term “Guarantied Obligations” is used herein in its most comprehensive sense and includes:

(a) any and all Obligations of Company, in each case now or hereafter made, incurred or created, whether absolute or contingent, liquidated or unliquidated, whether due or not due, and however arising under or in connection with the Credit Agreement and the other Loan Documents, including those arising under successive borrowing transactions under the Credit Agreement which shall either continue the Obligations of Company or from time to time renew them after they have been satisfied and including interest which, but for the filing of a petition in bankruptcy with respect to Company, would have accrued on any Guarantied Obligations, whether or not a claim is allowed against Company for such interest in the related bankruptcy proceeding; and

(b) those expenses set forth in subsection 2.8.

2.2 Limitation on Amount Guarantied; Contribution by Guarantors. (a) Anything contained in this Guaranty to the contrary notwithstanding, if any Fraudulent Transfer Law (as hereinafter defined) is determined by a court of competent jurisdiction to be applicable to the obligations of any Guarantor under this Guaranty, such obligations of such Guarantor hereunder shall be limited to a maximum aggregate amount equal to the largest amount that would not render its obligations hereunder subject to

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avoidance as a fraudulent transfer or conveyance under Section 548 of Title 11 of the United States Code or any applicable provisions of comparable state law (collectively, the “Fraudulent Transfer Laws”), in each case after giving effect to all other liabilities of such Guarantor, contingent or otherwise, that are relevant under the Fraudulent Transfer Laws (specifically excluding, however, any liabilities of such Guarantor (x) in respect of intercompany indebtedness to Company or other affiliates of Company to the extent that such indebtedness would be discharged in an amount equal to the amount paid by such Guarantor hereunder and (y) under any guaranty of Indebtedness of Company or its Subsidiaries subordinated or junior in right of payment to the Guarantied Obligations which guaranty contains a limitation as to maximum amount similar to that set forth in this subsection 2.2(a), pursuant to which the liability of such Guarantor hereunder is included in the liabilities taken into account in determining such maximum amount) and after giving effect as assets to the value (as determined under the applicable provisions of the Fraudulent Transfer Laws) of any rights to subrogation, reimbursement, indemnification or contribution of such Guarantor pursuant to applicable law or pursuant to the terms of any agreement (including any such right of contribution under subsection 2.2(b).

(b) Guarantors under this Guaranty together desire to allocate among themselves in a fair and equitable manner, their obligations arising under this Guaranty. Accordingly, in the event any payment or distribution is made on any date by any Guarantor under this Guaranty (a “Funding Guarantor”) that exceeds its Fair Share (as defined below) as of such date, that Funding Guarantor shall be entitled to a contribution from each of the other Guarantors in the amount of such other Guarantor’s Fair Share Shortfall (as defined below) as of such date, with the result that all such contributions will cause each Guarantor’s Aggregate Payments (as defined below) to equal its Fair Share as of such date. “Fair Share” means, with respect to a Guarantor as of any date of determination, an amount equal to (i) the ratio of (x) the Adjusted Maximum Amount (as defined below) with respect to such Guarantor to (y) the aggregate of the Adjusted Maximum Amounts with respect to all Guarantors multiplied by (ii) the aggregate amount paid or distributed on or before such date by all Funding Guarantors under this Guaranty in respect of the obligations guarantied. “Fair Share Shortfall” means, with respect to a Guarantor as of any date of determination, the excess, if any, of the Fair Share of such Guarantor over the Aggregate Payments of such Guarantor. “Adjusted Maximum Amount” means, with respect to a Guarantor as of any date of determination, the maximum aggregate amount of the obligations of such Guarantor under this Guaranty determined as of such date, in the case of any Guarantor, in accordance with subsection 2.2(a); provided that, solely for purposes of calculating the “Adjusted Maximum Amount” with respect to any Guarantor for purposes of this subsection 2.2(b), any assets or liabilities of such Guarantor arising by virtue of any rights to subrogation, reimbursement or indemnification or any rights to or obligations of contribution hereunder shall not be considered as assets or liabilities of such Guarantor. “Aggregate Payments” means, with respect to a Guarantor as of any date of determination, an amount equal to (i) the aggregate amount of all payments and distributions made on or before such date by such Guarantor in respect of this Guaranty (including in respect of this subsection 2.2(b)) minus (ii) the aggregate amount of all payments received on or before such date by such Guarantor from the other Guarantors as contributions under this

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subsection 2.2(b). The amounts payable as contributions hereunder shall be determined as of the date on which the related payment or distribution is made by the applicable Funding Guarantor. The allocation among Guarantors of their obligations as set forth in this subsection 2.2(b) shall not be construed in any way to limit the liability of any Guarantor hereunder.

2.3 Payment by Guarantors; Application of Payments. Subject to the provisions of subsection 2.2(a), Guarantors hereby jointly and severally agree, in furtherance of the foregoing and not in limitation of any other right which any Beneficiary may have at law or in equity against any Guarantor by virtue hereof, that upon the failure of Company to pay any of the Guarantied Obligations when and as the same shall become due, whether at stated maturity, by required prepayment, declaration, acceleration, demand or otherwise (including amounts that would become due but for the operation of the automatic stay under Section 362(a) of the Bankruptcy Code, 11 U.S.C. § 362(a)), Guarantors will upon demand pay, or cause to be paid, in cash, to Guarantied Party for the ratable benefit of Beneficiaries, an amount equal to the sum of the unpaid principal amount of all Guarantied Obligations then due as aforesaid, accrued and unpaid interest on such Guarantied Obligations (including interest which, but for the filing of a petition in bankruptcy with respect to Company, would have accrued on such Guarantied Obligations, whether or not a claim is allowed against Company for such interest in the related bankruptcy proceeding) and all other Guarantied Obligations then owed to Beneficiaries as aforesaid. All such payments shall be applied promptly from time to time by Guarantied Party as provided in subsection 2.4C of the Credit Agreement.

2.4 Liability of Guarantors Absolute. Each Guarantor agrees that its obligations hereunder are irrevocable, absolute, independent and unconditional and shall not be affected by any circumstance which constitutes a legal or equitable discharge of a guarantor or surety other than payment in full of the Guarantied Obligations. In furtherance of the foregoing and without limiting the generality thereof, each Guarantor agrees as follows:

(a) This Guaranty is a guaranty of payment when due and not of collectibility.

(b) Guarantied Party may enforce this Guaranty upon the occurrence of an Event of Default under the Credit Agreement notwithstanding the existence of any dispute between Company and any Beneficiary with respect to the existence of such Event of Default.

(c) The obligations of each Guarantor hereunder are independent of the obligations of Company under the Loan Documents and the obligations of any other guarantor (including any other Guarantor) of the obligations of Company under the Loan Documents, and a separate action or actions may be brought and prosecuted against such Guarantor whether or not any action is brought against Company or any of such other guarantors and whether or not Company is joined in any such action or actions.

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(d) Payment by any Guarantor of a portion, but not all, of the Guarantied Obligations shall in no way limit, affect, modify or abridge any Guarantor’s liability for any portion of the Guarantied Obligations which has not been paid. Without limiting the generality of the foregoing, if Guarantied Party is awarded a judgment in any suit brought to enforce any Guarantor’s covenant to pay a portion of the Guarantied Obligations, such judgment shall not be deemed to release such Guarantor from its covenant to pay the portion of the Guarantied Obligations that is not the subject of such suit, and such judgment shall not, except to the extent satisfied by such Guarantor, limit, affect, modify or abridge any other Guarantor’s liability hereunder in respect of the Guarantied Obligations.

(e) Any Beneficiary, upon such terms as it deems appropriate, without notice or demand and without affecting the validity or enforceability of this Guaranty or giving rise to any reduction, limitation, impairment, discharge or termination of any Guarantor’s liability hereunder, from time to time may (i) renew, extend, accelerate, increase the rate of interest on, or otherwise change the time, place, manner or terms of payment of the Guarantied Obligations, (ii) settle, compromise, release or discharge, or accept or refuse any offer of performance with respect to, or substitutions for, the Guarantied Obligations or any agreement relating thereto and/or subordinate the payment of the same to the payment of any other obligations; (iii) request and accept other guaranties of the Guarantied Obligations and take and hold security for the payment of this Guaranty or the Guarantied Obligations; (iv) release, surrender, exchange, substitute, compromise, settle, rescind, waive, alter, subordinate or modify, with or without consideration, any security for payment of the Guarantied Obligations, any other guaranties of the Guarantied Obligations, or any other obligation of any Person (including any other Guarantor) with respect to the Guarantied Obligations; (v) enforce and apply any security now or hereafter held by or for the benefit of such Beneficiary in respect of this Guaranty or the Guarantied Obligations and direct the order or manner of sale thereof, or exercise any other right or remedy that such Beneficiary may have against any such security, in each case as such Beneficiary in its discretion may determine consistent with the Credit Agreement and any applicable security agreement, including foreclosure on any such security pursuant to one or more judicial or nonjudicial sales, whether or not every aspect of any such sale is commercially reasonable, and even though such action operates to impair or extinguish any right of reimbursement or subrogation or other right or remedy of any Guarantor against Company or any security for the Guarantied Obligations; and (vi) exercise any other rights available to it under the Loan Documents.

(f) This Guaranty and the obligations of Guarantors hereunder shall be valid and enforceable and shall not be subject to any reduction, limitation, impairment, discharge or termination for any reason (other than payment in full of the Guarantied Obligations), including the occurrence of any of the following, whether or not any Guarantor shall have had notice or knowledge of any of them: (i) any failure or omission to assert or enforce or agreement or election not to assert or enforce, or the stay or enjoining, by order of court, by operation of law

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or otherwise, of the exercise or enforcement of, any claim or demand or any right, power or remedy (whether arising under the Loan Documents, at law, in equity or otherwise) with respect to the Guarantied Obligations or any agreement relating thereto, or with respect to any other guaranty of or security for the payment of the Guarantied Obligations; (ii) any rescission, waiver, amendment or modification of, or any consent to departure from, any of the terms or provisions (including provisions relating to events of default) of the Credit Agreement, any of the other Loan Documents or any agreement or instrument executed pursuant thereto, or of any other guaranty or security for the Guarantied Obligations, in each case whether or not in accordance with the terms of the Credit Agreement or such Loan Document or any agreement relating to such other guaranty or security; (iii) the Guarantied Obligations, or any agreement relating thereto, at any time being found to be illegal, invalid or unenforceable in any respect; (iv) the application of payments received from any source (other than payments received pursuant to the other Loan Documents or from the proceeds of any security for the Guarantied Obligations) to the payment of indebtedness other than the Guarantied Obligations, even though any Beneficiary might have elected to apply such payment to any part or all of the Guarantied Obligations; (v) any Beneficiary’s consent to the change, reorganization or termination of the corporate structure or existence of Company or any of its Subsidiaries and to any corresponding restructuring of the Guarantied Obligations; (vi) any failure to perfect or continue perfection of a security interest in any collateral which secures any of the Guarantied Obligations; (vii) any defenses, set-offs or counterclaims which Company may allege or assert against any Beneficiary in respect of the Guarantied Obligations, including failure of consideration, breach of warranty, payment, statute of frauds, statute of limitations, accord and satisfaction and usury; and (viii) any other act or thing or omission, or delay to do any other act or thing, which may or might in any manner or to any extent vary the risk of any Guarantor as an obligor in respect of the Guarantied Obligations.

2.5 Waivers by Guarantors. Each Guarantor hereby waives, for the benefit of Beneficiaries:

(a) any right to require any Beneficiary, as a condition of payment or performance by such Guarantor, to (i) proceed against Company, any other guarantor (including any other Guarantor) of the Guarantied Obligations or any other Person, (ii) proceed against or exhaust any security held from Company, any such other guarantor or any other Person, (iii) proceed against or have resort to any balance of any deposit account or credit on the books of any Beneficiary in favor of Company or any other Person, or (iv) pursue any other remedy in the power of any Beneficiary whatsoever;

(b) any defense arising by reason of the incapacity, lack of authority or any disability or other defense of Company including any defense based on or arising out of the lack of validity or the unenforceability of the Guarantied Obligations or any agreement or instrument relating thereto or by reason of the cessation of the liability of Company from any cause other than payment in full of the Guarantied Obligations;

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(c) any defense based upon any statute or rule of law which provides that the obligation of a surety must be neither larger in amount nor in other respects more burdensome than that of the principal;

(d) any defense based upon any Beneficiary’s errors or omissions in the administration of the Guarantied Obligations, except behavior which amounts to bad faith;

(e) (i) any principles or provisions of law, statutory or otherwise, which are or might be in conflict with the terms of this Guaranty and any legal or equitable discharge of such Guarantor’s obligations hereunder, (ii) the benefit of any statute of limitations affecting such Guarantor’s liability hereunder or the enforcement hereof, (iii) any rights to set-offs, recoupments and counterclaims, and (iv) promptness, diligence and any requirement that any Beneficiary protect, secure, perfect or insure any security interest or lien or any property subject thereto;

(f) notices, demands, presentments, protests, notices of protest, notices of dishonor and notices of any action or inaction, including acceptance of this Guaranty, notices of default under the Credit Agreement or any agreement or instrument related thereto, notices of any renewal, extension or modification of the Guarantied Obligations or any agreement related thereto, notices of any extension of credit to Company and notices of any of the matters referred to in subsection 2.4 and any right to consent to any thereof; and

(g) any defenses or benefits that may be derived from or afforded by law which limit the liability of or exonerate guarantors or sureties, or which may conflict with the terms of this Guaranty.

2.6 Guarantors’ Rights of Subrogation, Contribution, Etc. Each Guarantor hereby waives, until the Guarantied Obligations shall have been indefeasibly paid in full and the Commitments shall have terminated and all Letters of Credit shall have expired or been cancelled, any claim, right or remedy, direct or indirect, that such Guarantor now has or may hereafter have against Company or any of its assets in connection with this Guaranty or the performance by such Guarantor of its obligations hereunder, in each case whether such claim, right or remedy arises in equity, under contract, by statute under common law or otherwise and including (a) any right of subrogation, reimbursement or indemnification that such Guarantor now has or may hereafter have against Company, (b) any right to enforce, or to participate in, any claim, right or remedy that any Beneficiary now has or may hereafter have against Company, and (c) any benefit of, and any right to participate in, any collateral or security now or hereafter held by any Beneficiary. In addition, until the Guarantied Obligations shall have been indefeasibly paid in full and the Commitments shall have terminated and all Letters of Credit shall have expired or been cancelled, each Guarantor shall withhold

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exercise of any right of contribution such Guarantor may have against any other guarantor (including any other Guarantor) of the Guarantied Obligations (including any such right of contribution under subsection 2.2(b)). Each Guarantor further agrees that, to the extent the waiver or agreement to withhold the exercise of its rights of subrogation, reimbursement, indemnification and contribution as set forth herein is found by a court of competent jurisdiction to be void or voidable for any reason, any rights of subrogation, reimbursement or indemnification such Guarantor may have against Company or against any collateral or security, and any rights of contribution such Guarantor may have against any such other guarantor, shall be junior and subordinate to any rights any Beneficiary may have against Company, to all right, title and interest any Beneficiary may have in any such collateral or security, and to any right any Beneficiary may have against such other guarantor. If any amount shall be paid to any Guarantor on account of any such subrogation, reimbursement, indemnification or contribution rights at any time when all Guarantied Obligations shall not have been paid in full, such amount shall be held in trust for Guarantied Party on behalf of Beneficiaries and shall forthwith be paid over to Guarantied Party for the benefit of Beneficiaries to be credited and applied against the Guarantied Obligations, whether matured or unmatured, in accordance with the terms hereof.

2.7 Subordination of Other Obligations. Any indebtedness of Company or any Guarantor now or hereafter held by any Guarantor (the “Obligee Guarantor”) is hereby subordinated in right of payment to the Guarantied Obligations, and any such indebtedness collected or received by the Obligee Guarantor after an Event of Default has occurred and is continuing shall be held in trust for Guarantied Party on behalf of Beneficiaries and shall forthwith be paid over to Guarantied Party for the benefit of Beneficiaries to be credited and applied against the Guarantied Obligations but without affecting, impairing or limiting in any manner the liability of the Obligee Guarantor under any other provision of this Guaranty.

2.8 Expenses. Guarantors jointly and severally agree to pay, or cause to be paid, on demand, and to save Beneficiaries harmless against liability for, any and all costs and expenses (including reasonable fees and disbursements of counsel and reasonable allocated costs of internal counsel) incurred or expended by any Beneficiary in connection with the enforcement of or preservation of any rights under this Guaranty.

2.9 Continuing Guaranty. This Guaranty is a continuing guaranty and shall remain in effect until all of the Guarantied Obligations shall have been paid in full and the Commitments shall have terminated and all Letters of Credit shall have expired or been cancelled. Each Guarantor hereby irrevocably waives any right to revoke this Guaranty as to future transactions giving rise to any Guarantied Obligations.

2.10 Rights Cumulative. The rights, powers and remedies given to Beneficiaries by this Guaranty are cumulative and shall be in addition to and independent of all rights, powers and remedies given to Beneficiaries by virtue of any statute or rule of law or in any of the other Loan Documents or any agreement between any Guarantor and any Beneficiary or Beneficiaries or between Company and any Beneficiary or Beneficiaries. Any forbearance or failure to exercise, and any delay by any Beneficiary in exercising, any right, power or remedy hereunder shall not impair any such right, power or remedy or be construed to be a waiver thereof, nor shall it preclude the further exercise of any such right, power or remedy.

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2.11 Bankruptcy; Post-Petition Interest; Reinstatement of Guaranty. (a) So long as any Guarantied Obligations remain outstanding, no Guarantor shall, without the prior written consent of Guarantied Party acting pursuant to the instructions of Requisite Lenders, commence or join with any other Person in commencing any bankruptcy, reorganization or insolvency proceedings of or against Company. The obligations of Guarantors under this Guaranty shall not be reduced, limited, impaired, discharged, deferred, suspended or terminated by any proceeding, voluntary or involuntary, involving the bankruptcy, insolvency, receivership, reorganization, liquidation or arrangement of Company or by any defense which Company may have by reason of the order, decree or decision of any court or administrative body resulting from any such proceeding.

(b) Each Guarantor acknowledges and agrees that any interest on any portion of the Guarantied Obligations which accrues after the commencement of any proceeding referred to in clause (a) above (or, if interest on any portion of the Guarantied Obligations ceases to accrue by operation of law by reason of the commencement of said proceeding, such interest as would have accrued on such portion of the Guarantied Obligations if said proceedings had not been commenced) shall be included in the Guarantied Obligations because it is the intention of Guarantors and Beneficiaries that the Guarantied Obligations which are guarantied by Guarantors pursuant to this Guaranty should be determined without regard to any rule of law or order which may relieve Company of any portion of such Guarantied Obligations. Guarantors will permit any trustee in bankruptcy, receiver, debtor in possession, assignee for the benefit of creditors or similar person to pay Guarantied Party, or allow the claim of Guarantied Party in respect of, any such interest accruing after the date on which such proceeding is commenced.

(c) In the event that all or any portion of the Guarantied Obligations are paid by Company, the obligations of Guarantors hereunder shall continue and remain in full force and effect or be reinstated, as the case may be, in the event that all or any part of such payment(s) are rescinded or recovered directly or indirectly from any Beneficiary as a preference, fraudulent transfer or otherwise, and any such payments which are so rescinded or recovered shall constitute Guarantied Obligations for all purposes under this Guaranty.

2.12 Notice of Events. As soon as Guarantor obtains knowledge thereof, Guarantor shall give Guarantied Party written notice of any condition or event which has resulted in (a) a material adverse change in the financial condition of Guarantor or Company or (b) any Event of Default or Potential Event of Default.

2.13 Set Off. In addition to any other rights any Beneficiary may have under law or under this Guaranty, such Beneficiary is authorized at any time or from time to time while an Event of Default has occurred and is continuing, without notice (any such

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notice being hereby expressly waived), to set off and to appropriate and to apply any and all deposits (general or special, including indebtedness evidenced by certificates of deposit, whether matured or unmatured) and any other indebtedness of such Beneficiary owing to Guarantor and any other property of Guarantor held by any Beneficiary to or for the credit or the account of Guarantor against and on account of the Guarantied Obligations and liabilities of Guarantor to any Beneficiary under this Guaranty.

2.14 Representations and Warranties. Each Guarantor represents and warrants as to itself, on the date that it becomes a party hereto, on the Term Loan Funding Date, on each Funding Date (other than, in the case of Funding Dates occurring after the Term Loan Funding Date, subsections 5.4 and 5.6 of the Credit Agreement) and on the date of the issuance of each Letter of Credit (other than, in the case of Funding Dates occurring after the Term Loan Funding Date, subsections 5.4 and 5.6 of the Credit Agreement) that all representations and warranties relating to it contained in the Loan Documents are true, correct and complete in all material respects, except to the extent such representations and warranties specifically relate to an earlier date, in which case such representations and warranties were true, correct and complete in all material respects on and as of such earlier date.

2.15 Covenants. Each Guarantor covenants and agrees that such Guarantor will perform and observe, and cause each of its Subsidiaries to perform and observe, all of the terms, covenants and agreements set forth in the Loan Documents that are required to be, or that Company has agreed to cause to be, performed or observed by such Guarantor or Subsidiary.

2.16 Information. Each Guarantor assumes all responsibility for being and keeping itself informed of the Company’s and each other Loan Party’s financial condition and assets and of all other circumstances bearing upon the risk of nonpayment of the Guaranteed Obligations and the nature, scope and extent of the risks that such Guarantor assumes and incurs hereunder, and agrees that neither the Guarantied Party nor any other Beneficiary will have any duty to advise such Guarantor of information known to it or any of them regarding such circumstances or risks.

SECTION 3. MISCELLANEOUS

3.1 Survival of Warranties. All agreements, representations and warranties made herein shall survive the execution and delivery of this Guaranty and the other Loan Documents and any increase in the Commitments under the Credit Agreement.

3.2 Notices. Any communications between Guarantied Party and any Guarantor and any notices or requests provided herein to be given may be given by mailing the same, postage prepaid, or by telex, facsimile transmission or cable to each such party at its address set forth in the Credit Agreement, on the signature pages hereof or to such other addresses as each such party may in writing hereafter indicate. Any notice, request or demand to or upon Guarantied Party or any Guarantor shall not be effective until received.

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3.3 Severability. In case any provision in or obligation under this Guaranty shall be invalid, illegal or unenforceable in any jurisdiction, the validity, legality and enforceability of the remaining provisions or obligations, or of such provision or obligation in any other jurisdiction, shall not in any way be affected or impaired thereby.

3.4 Amendments and Waivers. (a) No failure or delay by the Guarantied Party or any other Beneficiary in exercising any right or power hereunder or under any other Loan Document shall operate as a waiver hereof or thereof, nor shall any single or partial exercise of any such right or power, or any abandonment or discontinuance of steps to enforce such a right or power, preclude any other or further exercise thereof or the exercise of any other right or power. The rights and remedies of the Guarantied Party and the other Beneficiaries hereunder and under the other Loan Documents are cumulative and are not exclusive of any rights or remedies that they would otherwise have. No waiver of any provision of any Loan Document or consent to any departure by any Loan Party therefrom shall in any event be effective unless the same shall be permitted by paragraph (b) of this Section 3.4 and then such waiver or consent shall be effective only in the specific instance and for the purpose for which given. No notice or demand on any Loan Party in any case shall entitle any Loan Party to any other or further notice or demand in similar or other circumstances.

(b) No amendment, modification, termination or waiver of any provision of this Guaranty, and no consent to any departure by any Guarantor therefrom, shall in any event be effective without the written concurrence of Guarantied Party and, in the case of any such amendment or modification, each Guarantor against whom enforcement of such amendment or modification is sought. Any such waiver or consent shall be effective only in the specific instance and for the specific purpose for which it was given. Any amendment, modification, termination, waiver or consent effected in accordance with this subsection 3.4(b) shall be binding upon each Beneficiary.

3.5 Headings. Section and subsection headings in this Guaranty are included herein for convenience of reference only and shall not constitute a part of this Guaranty for any other purpose or be given any substantive effect.

3.6 Applicable Law; Rules of Construction. THIS GUARANTY AND THE RIGHTS AND OBLIGATIONS OF GUARANTORS AND BENEFICIARIES HEREUNDER SHALL BE GOVERNED BY, AND SHALL BE CONSTRUED AND ENFORCED IN ACCORDANCE WITH, THE INTERNAL LAWS OF THE STATE OF NEW YORK. The rules of construction set forth in subsection 1.3 of the Credit Agreement shall be applicable to this Guaranty mutatis mutandis.

3.7 Successors and Assigns. This Guaranty is a continuing guaranty and shall be binding upon each Guarantor and its respective successors and assigns. This Guaranty shall inure to the benefit of Beneficiaries and their respective successors and assigns. No Guarantor shall assign this Guaranty or any of the rights or obligations of such Guarantor hereunder without the prior written consent of all Lenders. Any

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Beneficiary may, without notice or consent, assign its interest in this Guaranty in whole or in part. The terms and provisions of this Guaranty shall inure to the benefit of any transferee or assignee of any Loan, and in the event of such transfer or assignment the rights and privileges herein conferred upon such Beneficiary shall automatically extend to and be vested in such transferee or assignee, all subject to the terms and conditions hereof.

3.8 Consent to Jurisdiction and Service of Process. ALL JUDICIAL PROCEEDINGS BROUGHT AGAINST ANY GUARANTOR ARISING OUT OF OR RELATING TO THIS GUARANTY, OR ANY OBLIGATIONS HEREUNDER, MAY BE BROUGHT IN ANY STATE OR FEDERAL COURT OF COMPETENT JURISDICTION IN THE STATE, COUNTY AND CITY OF NEW YORK. BY EXECUTING AND DELIVERING THIS AGREEMENT, EACH GUARANTOR, FOR ITSELF AND IN CONNECTION WITH ITS PROPERTIES, IRREVOCABLY

(I) ACCEPTS GENERALLY AND UNCONDITIONALLY THE NONEXCLUSIVE JURISDICTION AND VENUE OF SUCH COURTS;

(II) WAIVES ANY DEFENSE OF FORUM NON CONVENIENS WITH RESPECT TO ANY STATE OR FEDERAL COURT OF COMPETENT JURISDICTION IN THE STATE, COUNTY AND CITY OF NEW YORK;

(III) AGREES THAT SERVICE OF ALL PROCESS IN ANY SUCH PROCEEDING IN ANY SUCH COURT MAY BE MADE BY REGISTERED OR CERTIFIED MAIL, RETURN RECEIPT REQUESTED, TO SUCH GUARANTOR AT ITS ADDRESS PROVIDED IN ACCORDANCE WITH SUBSECTION 3.2;

(IV) AGREES THAT SERVICE AS PROVIDED IN CLAUSE (III) ABOVE IS SUFFICIENT TO CONFER PERSONAL JURISDICTION OVER SUCH GUARANTOR IN ANY SUCH PROCEEDING IN ANY SUCH COURT, AND OTHERWISE CONSTITUTES EFFECTIVE AND BINDING SERVICE IN EVERY RESPECT;

(V) AGREES THAT BENEFICIARIES RETAIN THE RIGHT TO SERVE PROCESS IN ANY OTHER MANNER PERMITTED BY LAW OR TO BRING PROCEEDINGS AGAINST SUCH GUARANTOR IN THE COURTS OF ANY OTHER JURISDICTION; AND

(VI) AGREES THAT THE PROVISIONS OF THIS SUBSECTION 3.8 RELATING TO JURISDICTION AND VENUE SHALL BE BINDING AND ENFORCEABLE TO THE FULLEST EXTENT PERMISSIBLE UNDER NEW YORK GENERAL OBLIGATIONS LAW SECTION 5-1402 OR OTHERWISE.

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3.9 Waiver of Trial by Jury. EACH GUARANTOR AND, BY ITS ACCEPTANCE OF THE BENEFITS HEREOF, EACH BENEFICIARY HEREBY AGREES TO WAIVE ITS RESPECTIVE RIGHTS TO A JURY TRIAL OF ANY CLAIM OR CAUSE OF ACTION BASED UPON OR ARISING OUT OF THIS GUARANTY. The scope of this waiver is intended to be all encompassing of any and all disputes that may be filed in any court and that relate to the subject matter of this transaction, including contract claims, tort claims, breach of duty claims and all other common law and statutory claims. Each Guarantor and, by its acceptance of the benefits hereof, each Beneficiary, each (i) acknowledges that this waiver is a material inducement for such Guarantor and Beneficiaries to enter into a business relationship, that such Guarantor and Beneficiaries have already relied on this waiver in entering into this Guaranty or accepting the benefits thereof, as the case may be, and that each will continue to rely on this waiver in their related future dealings and (ii) further warrants and represents that each has reviewed this waiver with its legal counsel, and that each knowingly and voluntarily waives its jury trial rights following consultation with legal counsel. THIS WAIVER IS IRREVOCABLE, MEANING THAT IT MAY NOT BE MODIFIED EITHER ORALLY OR IN WRITING (OTHER THAN BY A MUTUAL WRITTEN WAIVER SPECIFICALLY REFERRING TO THIS SUBSECTION 3.9 AND EXECUTED BY GUARANTIED PARTY AND EACH GUARANTOR), AND THIS WAIVER SHALL APPLY TO ANY SUBSEQUENT AMENDMENTS, RENEWALS, SUPPLEMENTS OR MODIFICATIONS TO THIS GUARANTY. In the event of litigation, this Guaranty may be filed as a written consent to a trial by the court.

3.10 No Other Writing. This writing is intended by Guarantors and Beneficiaries as the final expression of this Guaranty and is also intended as a complete and exclusive statement of the terms of their agreement with respect to the matters covered hereby. No course of dealing, course of performance or trade usage, and no parol evidence of any nature, shall be used to supplement or modify any terms of this Guaranty. There are no conditions to the full effectiveness of this Guaranty.

3.11 Further Assurances. At any time or from time to time, upon the request of Guarantied Party, Guarantors shall execute and deliver such further documents and do such other acts and things as Guarantied Party may reasonably request in order to effect fully the purposes of this Guaranty.

3.12 Additional Guarantors. The initial Guarantors hereunder shall be such of the Domestic Subsidiaries of Company as are signatories hereto on the date hereof. From time to time subsequent to the date hereof, additional Domestic Subsidiaries of Company may become parties hereto, as additional Guarantors (each an “Additional Guarantor”), by executing a counterpart of this Guaranty. Upon delivery of any such counterpart to Administrative Agent, notice of which is hereby waived by Guarantors, each such Additional Guarantor shall be a Guarantor and shall be as fully a party hereto as if such Additional Guarantor were an original signatory hereof. Each Guarantor expressly agrees that its obligations arising hereunder shall not be affected or diminished by the addition or release of any other Guarantor hereunder, nor by any election of Administrative Agent not to cause any Subsidiary of Company to become an Additional Guarantor hereunder. This Guaranty shall be fully effective as to any Guarantor that is or becomes a party hereto regardless of whether any other Person becomes or fails to become or ceases to be a Guarantor hereunder.

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3.13 Counterparts; Effectiveness. This Guaranty may be executed in any number of counterparts and by the different parties hereto in separate counterparts, each of which when so executed and delivered shall be deemed to be an original for all purposes; but all such counterparts together shall constitute but one and the same instrument. This Guaranty shall become effective as to each Guarantor upon the execution of a counterpart hereof by such Guarantor (whether or not a counterpart hereof shall have been executed by any other Guarantor) and receipt by Guarantied Party of written or telephonic notification of such execution and authorization of delivery thereof. Delivery of an executed counterpart of a signature page of this Guaranty by telefacsimile or electronic transmission (in PDF format) shall be effective as delivery of a manually executed counterpart of this Guaranty.

3.14 Guarantied Party as Agent.

(a) Guarantied Party has been appointed to act as Guarantied Party hereunder by Lenders. Guarantied Party shall be obligated, and shall have the right hereunder, to make demands, to give notices, to exercise or refrain from exercising any rights, and to take or refrain from taking any action, solely in accordance with this Guaranty and the Credit Agreement; provided that Guarantied Party shall exercise, or refrain from exercising, any remedies hereunder in accordance with the instructions of Requisite Lenders.

(b) Guarantied Party shall at all times be the same Person that is Administrative Agent under the Credit Agreement. Written notice of resignation by Administrative Agent pursuant to subsection 9.5 of the Credit Agreement shall also constitute notice of resignation as Guarantied Party under this Guaranty; removal of Administrative Agent under the Credit Agreement shall also constitute removal as Guarantied Party under this Guaranty; and appointment of a successor Agent pursuant to subsection 9.5 of the Credit Agreement shall also constitute appointment of a successor Guarantied Party under this Guaranty. Upon the acceptance of any appointment as Administrative Agent under subsection 9.5 of the Credit Agreement by a successor Administrative Agent, that successor Administrative Agent shall thereupon succeed to and become vested with all the rights, powers, privileges and duties of the resigning or removed Guarantied Party under this Guaranty, and the resigning or removed Guarantied Party under this Guaranty shall promptly (i) transfer to such successor Guarantied Party all sums held hereunder, together with all records and other documents necessary or appropriate in connection with the performance of the duties of the successor Guarantied Party under this Guaranty, and (ii) take such other actions as may be necessary or appropriate in connection with the assignment to such successor Guarantied Party of the rights created hereunder, whereupon such retiring or removed Guarantied Party shall be discharged from its duties and obligations under this Guaranty. After any retiring or removed Guarantied Party’s resignation or removal hereunder as Guarantied Party, the provisions of this Guaranty shall inure to its benefit as to any actions taken or omitted to be taken by it under this Guaranty while it was Guarantied Party hereunder.

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3.15 Release of Guarantors. A Guarantor shall automatically be released from its Guarantied Obligations upon the consummation of any transaction permitted by the Credit Agreement as a result of which such Guarantor ceases to be a Domestic Subsidiary; provided that, if so required by the Credit Agreement, the Requisite Lenders shall have consented to such transaction and the terms of such consent shall not have provided otherwise.

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IN WITNESS WHEREOF, each of the undersigned Guarantors has caused this Guaranty to be duly executed and delivered by its officer thereunto duly authorized as of the date first written above.

[Subsidiary Guaranty]

[Subsidiary Guaranty]

BYFIELD DRUG, INC.

CARE CONTINUUM, INC.

CFI OF NEW JERSEY, INC.

CHESAPEAKE INFUSION, INC.

CONNECTYOURCARE COMPANY LLC

CONNECTYOURCARE, LLC

CURASCRIPT PBM SERVICES, INC.

DIVERSIFIED PHARMACEUTICAL SERVICES, INC.

ESI ACQUISITION, INC.

ESI CLAIMS, INC.

ESI ENTERPRISES, LLC

ESI MAIL ORDER PROCESSING, INC.

EXPRESS SCRIPTS CANADA HOLDING CO.

EXPRESS SCRIPTS CANADA HOLDING, LLC

EXPRESS SCRIPTS, INC.

EXPRESS SCRIPTS PHARMACEUTICAL PROCUREMENT, LLC

EXPRESS SCRIPTS SERVICES COMPANY FRECO, INC.

FREEDOM SERVICE COMPANY, LLC

HEALTHBRIDGE, INC.

HEALTHBRIDGE REIMBURSEMENT AND PRODUCT SUPPORT, INC.

IBIOLOGIC, INC.

IVTX, INC.

LYNNFIELD COMPOUNDING CENTER, INC.

LYNNFIELD DRUG, INC.

MATRIX GPO LLC

NATIONAL PRESCRIPTION ADMINISTRATORS, INC.

PRIORITYHEALTHCARE.COM, INC.

IN WITNESS WHEREOF, the undersigned Additional Guarantor has caused this Guaranty to be duly executed and delivered by its officer thereunto duly authorized as of                     ,             .