UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Rule 13d-101)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO § 240.13d-1(a)

AND AMENDMENTS THERETO FILED PURSUANT TO § 240.13d-2(a)

UNDER THE SECURITIES EXCHANGE ACT OF 1934

SANTARUS, INC.

(Name of Issuer)

COMMON STOCK, $0.0001 PAR VALUE

(Title of Class of Securities)

802817304

(CUSIP Number)

Rick D. Scruggs, Executive Vice President, Business Development

William Bertrand, Jr., Senior Vice President, General Counsel

Salix Pharmaceuticals, Ltd.

8510 Colonnade Center Drive

Raleigh, NC 27615

(919) 862-1000

(Name, Address and Telephone Numbers of Persons Authorized to Receive Notices and Communications)

With Copies to:

David B.H. Martin, Esq.

Keir D. Gumbs, Esq.

Covington & Burling LLP

1201 Pennsylvania Avenue, N.W.

Washington, DC 20004

(202) 662-6000

November 7, 2013

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.    ¨

Item 1. Security and Issuer.

This statement on Schedule 13D (this “Schedule 13D”) relates to the common stock, par value $0.0001 per share (the “Common Stock”), of Santarus, Inc., a Delaware corporation (“Santarus”). Santarus’ principal executive offices are located at 3611 Valley Centre Drive, Suite 400, San Diego, California 92130.

Item 2. Identity and Background.

This Schedule 13D is being filed jointly on behalf of (i) Salix Pharmaceuticals, Ltd., a Delaware corporation (“Parent”), (ii) Salix Pharmaceuticals, Inc., a California corporation and a wholly owned subsidiary of Parent (“Intermediary”) and (iii) Willow Acquisition Sub Corporation, a Delaware corporation and a wholly owned subsidiary of Intermediary (“Merger Sub”).

The address of the principal business and principal office of each of Parent, Intermediary and Merger Sub is 8510 Colonnade Center Drive, Raleigh, North Carolina 27615. The telephone number of each of Parent, Intermediary and Merger Sub is (919) 862-1000. Each of Parent and Intermediary is a specialty pharmaceutical company dedicated to acquiring, developing and commercializing prescription drugs and medical devices used in the treatment of a variety of gastrointestinal disorders, which are those affecting the digestive tract. Merger Sub was formed solely for the purpose of effecting the transactions contemplated by the Merger Agreement (as defined below) and has not engaged in any activities except in connection with these transactions.

Parent, Intermediary and Merger Sub are collectively hereinafter referred to as the “Reporting Persons.” The Reporting Persons have entered into a Joint Filing Agreement, a copy of which is filed with this Schedule 13D as Exhibit 1.

The name, business address, present principal occupation or employment and citizenship of each executive officer and director of each of Parent, Intermediary and Merger Sub is set forth on Schedule A. During the last five years, none of the Reporting Persons nor, to the best knowledge of the Reporting Persons, any of the persons listed on Schedule A, has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or was a party to a civil proceeding of a judicial or administrative body of competent jurisdiction as a result of which such person was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws, or finding any violation with respect to such laws.

Item 3. Source and Amount of Funds or Other Consideration.

The total amount of funds required by the Reporting Persons to consummate the Offer (as defined below), described in Item 4 of this Schedule 13D (the terms of which are hereby incorporated by reference), and purchase all outstanding shares of Common Stock in the Offer and to provide funding in connection with the Merger is approximately $2.6 billion, plus related fees and expenses. The Reporting Persons expect to fund these payments through a combination of cash on hand and $1.95 billion in committed financing from Jefferies Finance LLC (“Jefferies”). Parent has received a commitment letter (the “Commitment Letter”) from Jefferies, pursuant to which Jefferies has agreed to provide Parent with a combination of a term loan facility in the amount of $1.2 billion and (in the event that a planned notes offering by Parent is not consummated prior to, or concurrently with, the Offer and the Merger (as defined below)) a bridge loan facility in the amount of $750 million. The obligation of Jefferies to provide financing is subject to customary conditions. The foregoing description of the Commitment Letter does not purport to be complete and is qualified in its entirety by reference to the Commitment Letter, which is attached as Exhibit 2 hereto and incorporated herein by reference.

The information set forth or incorporated by reference in Item 4 is incorporated by reference in this Item 3.

Item 4. Purpose of Transaction.

On November 7, 2013, Parent, Intermediary and Merger Sub entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Santarus.

Pursuant to the terms and subject to the conditions of the Merger Agreement, Parent has agreed to cause Merger Sub to commence a cash tender offer (the “Offer”) to purchase all of the issued and outstanding shares of Common Stock at a price per share equal to $32.00 (the “Offer Price”), net to the seller in cash, without interest, less any applicable withholding taxes. The obligation of Parent and Merger Sub to consummate the Offer is subject to the condition that, immediately prior to the expiration of the Offer, there be validly tendered and not validly withdrawn the number of shares of Common Stock that, when added to the shares of Common Stock then owned by Parent and its subsidiaries, would represent one share more than one half of the sum of (i) all shares of Common Stock then outstanding and (ii) all shares of Common Stock that Santarus may be required to issue upon the vesting (including vesting solely as a result of the consummation of the Offer), conversion, settlement or exercise of all then outstanding warrants, options, benefit plans,

obligations or securities convertible or exchangeable into shares of Common Stock, or other rights to acquire or be issued shares of Common Stock (including all then outstanding Santarus stock options), regardless of the conversion or exercise price or other terms and conditions thereof. The consummation of the Offer is also subject to the satisfaction of other customary conditions, including the termination or expiration of the waiting period applicable to the Offer under the Hart-Scott-Rodino Antitrust Improvements Act of 1976. Consummation of the Offer is not subject to any financing condition.

As soon as practicable following the consummation of the Offer and subject to the satisfaction or waiver of the remaining conditions set forth in the Merger Agreement, Merger Sub will be merged with and into Santarus (the “Merger”), following which the separate existence of Merger Sub will cease and Santarus will continue as an indirect wholly owned subsidiary of Parent (the “Surviving Corporation”). The Merger will be governed by Section 251(h) of the General Corporation Law of the State of Delaware, with no stockholder vote required to consummate the Merger. Pursuant to the terms and subject to the conditions of the Merger Agreement, at the effective time of the Merger, each share of Common Stock issued and outstanding immediately prior to such effective time (other than (i) shares held in the treasury of Santarus, (ii) shares owned by Parent, Merger Sub or any wholly owned subsidiary of Parent or Santarus and (iii) shares that are held by any stockholders who properly demand appraisal in connection with the Merger) will be canceled and converted automatically into the right to receive an amount in cash equal to the Offer Price, without interest, less any applicable withholding taxes.

The Merger Agreement contains representations and warranties and covenants customary for a transaction of this nature, including, without limitation, covenants regarding (i) the conduct of the business of Santarus prior to the consummation of the Offer and (ii) the use of reasonable best efforts to cause the Offer, the Merger and the other transactions contemplated by the Merger Agreement to be consummated.

The Merger Agreement prohibits Santarus from soliciting or initiating discussions with third parties regarding other proposals to acquire Santarus, and Santarus has agreed to certain restrictions on its ability to respond to such proposals, subject to the fulfillment of certain fiduciary requirements of Santarus’ board of directors under Delaware law. The Merger Agreement can be terminated by Parent or Santarus under certain circumstances, including without limitation (i) by Parent if Santarus makes a Company Adverse Recommendation Change (as defined in the Merger Agreement) and (ii) by Santarus (A) to enter into a Superior Proposal (as defined in the Merger Agreement) and (B) if, under certain circumstances, Merger Sub fails to commence the Offer within the period specified by the Merger Agreement. In connection with the termination of the Merger Agreement under specified circumstances, including with respect to a Company Adverse Recommendation Change, Santarus is required to pay to Parent a termination fee.

The Merger Agreement has been attached as an exhibit to this Schedule 13D and is incorporated herein by reference to provide investors with information regarding the terms of the agreement and is not intended to modify or supplement any factual disclosures about the Reporting Persons or Santarus in Parent’s or Santarus’ respective public reports filed with the Securities and Exchange Commission (the “SEC”). In particular, the Merger Agreement and related summary are not intended to be, and should not be relied upon as, disclosures regarding any facts and circumstances relating to the Reporting Persons or Santarus. The representations and warranties in the Merger Agreement have been negotiated with the principal purpose of establishing the circumstances in which a party may have the right not to consummate the Offer if the representations and warranties of the other party prove to be untrue due to a change in circumstance or otherwise, and allocate risk between the parties, rather than establishing matters as facts.

Concurrently with the execution of the Merger Agreement, Parent and Merger Sub entered into a Tender and Support Agreement, dated as of November 7, 2013 (the “Support Agreement”), with the Santarus stockholders listed on the signature pages thereto (the “Supporting Stockholders”). Under the Support Agreement, the Supporting Stockholders have agreed to tender, and not withdraw, all shares of Common Stock beneficially owned by them as of the date of the Support Agreement or acquired by them after such date (collectively, the “Subject Shares”) no later than seven business days after the receipt by the Supporting Stockholders of all documents or instruments required to be delivered pursuant to the terms of the Offer. Notwithstanding the foregoing, the Supporting Stockholders will not be required to exercise any options or other equity awards under the Support Agreement. None of the Reporting Persons paid any consideration to the Supporting Stockholders in connection with the execution and delivery of the Support Agreement.

The Supporting Stockholders have also agreed that if their Subject Shares have not been previously accepted for payment pursuant to the Offer, at any meeting of the holders of shares of Common Stock the Supporting Stockholders will vote their Subject Shares against (i) any Acquisition Proposal or any Alternative Acquisition Agreement (each as defined in the Merger Agreement), (ii) any election of new directors to Santarus’ board of directors, other than nominees to Santarus’ board of directors who were serving as directors of Santarus on the date of the Support Agreement who are nominated for election by a majority of Santarus’ board of directors, or as otherwise provided in the Merger Agreement, (iii) any action, proposal, transaction or agreement that would reasonably be expected to result in a breach of any covenant, representation or warranty or any other obligation or agreement of such

Supporting Stockholder under the Support Agreement or of Santarus under the Merger Agreement and (iv) each of the following actions (other than the Offer and the Merger): (A) any extraordinary corporate transaction, such as a merger, consolidation or other business combination involving Santarus or its subsidiary, (B) any sale, lease or other transfer of a material amount of the assets of Santarus or its subsidiary, taken as a whole and (C) any reorganization, recapitalization, dissolution, liquidation or winding up of Santarus or its subsidiary. In furtherance of the Supporting Stockholders’ covenants under the Support Agreement, the Supporting Stockholders agreed to appoint Parent as their attorney-in-fact and proxy to attend all meetings of Santarus’ stockholders and to vote the Supporting Stockholders’ Subject Shares against the actions described in the immediately preceding sentence.

The Support Agreement limits the ability of the Supporting Stockholders to sell or otherwise transfer, encumber or grant proxies in respect of their Subject Shares. However, any Supporting Stockholder is permitted by the Support Agreement to transfer such stockholder’s Subject Shares under a trading plan pursuant to Rule 10b5-1 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), that existed as of November 7, 2013 (each, a “Rule 10b5-1 Plan”).

The Support Agreement will terminate upon certain circumstances, including upon (i) the effective time of the Merger, (ii) notice by Parent to the Supporting Stockholders, (iii) the termination of the Merger Agreement, (iv) the entry without the prior written consent of the Supporting Stockholders into an amendment or modification to the Merger Agreement or any waiver of any of Santarus’ rights under the Merger Agreement, in each case, that results in a decrease in the Offer Price, (v) the termination or withdrawal of the Offer by Parent or Merger Sub and (vi) the expiration of the Offer without Merger Sub having accepted for payment shares of Common Stock validly tendered in the Offer.

Based upon information provided by Santarus and the Supporting Stockholders, excluding options to purchase shares of Common Stock, the Supporting Stockholders beneficially owned, in the aggregate, 979,773 shares of Common Stock (representing approximately 1.5 percent of all outstanding shares of Common Stock) as of November 7, 2013. Including options to purchase shares of Common Stock exercisable on November 7, 2013 or becoming exercisable within 60 days thereafter, the Supporting Stockholders beneficially owned, in the aggregate, 6,236,082 shares of Common Stock (representing approximately 8.6 percent of all outstanding shares of Common Stock after giving effect to the exercise of such options) as of November 7, 2013.

The purpose of the Offer is to acquire control of, and ultimately following the Merger, the entire equity interest in, Santarus while allowing Santarus’ stockholders an opportunity to receive the Offer Price promptly by tendering their shares of Common Stock into the Offer. If the Offer is consummated, Parent will be entitled to elect or designate a number of directors, rounded up to the next whole number, on Santarus’ board of directors that is equal to the product of (i) the total number of directors on Santarus’ board of directors (after giving effect to the directors elected or designated by Parent) multiplied by (ii) the percentage that the aggregate number of shares of Common Stock then owned directly or indirectly by Parent bears to the total number of shares of Common Stock then outstanding, and Parent will be entitled to have such designees elected or appointed to such classes of Santarus’ board of directors so as to be as evenly distributed as possible among the three classes of Santarus’ board of directors.

After the consummation of the Offer, Parent and Merger Sub intend to consummate the Merger as promptly as practicable, subject to the satisfaction or waiver of certain conditions. At the effective time of the Merger, (i) the certificate of incorporation of the Surviving Corporation will be amended and restated in its entirety as set forth in an exhibit to the Merger Agreement, (ii) the bylaws of Merger Sub, as in effect immediately prior to the effective time of the Merger, will be the bylaws of the Surviving Corporation and (iii) the directors and officers of Merger Sub immediately prior to the effective time of the Merger will be the initial directors and officers of the Surviving Corporation.

Following the Merger, the Common Stock will no longer be traded on the NASDAQ Global Select Market, there will be no public market for the Common Stock and the registration of the Common Stock under the Exchange Act will be terminated.

Except as set forth in this Schedule 13D and in connection with the Offer and the Merger described above, Parent has no plan or proposals that relate to or would result in any of the transactions described in subparagraphs (a) through (j) of Item 4 of Schedule 13D.

The description contained in this Item 4 of the transactions contemplated by the Merger Agreement and the Support Agreement is qualified in its entirety by reference to the full texts of these agreements, the terms of which are incorporated herein by reference to Exhibit 3 and Exhibit 4, respectively, of this Schedule 13D.

About the Tender Offer

The Offer for the outstanding Common Stock has not yet commenced. The foregoing is neither an offer to purchase nor a solicitation of an offer to sell securities. At the time the Offer is commenced, Parent and Merger Sub will file a tender offer statement on Schedule TO with the SEC, and Santarus will file a solicitation/recommendation statement on Schedule 14D-9 with respect to the

Offer. The Offer to purchase shares of Common Stock will only be made pursuant to the offer to purchase, the letter of transmittal and related documents filed with such Schedule TO. The tender offer statement (including an offer to purchase, a related letter of transmittal and other offer documents) and the solicitation/recommendation statement, as each may be amended from time to time, will contain important information that should be read carefully by Santarus’ stockholders before any decision is made with respect to the Offer. These materials will be sent free of charge to all of Santarus’ stockholders when available. All stockholders of Santarus may obtain a free copy of the tender offer statement and the solicitation/recommendation statement (when available) on the SEC’s website: www.sec.gov or by directing such requests to the Information Agent for the Offer, which will be named in the tender offer statement. Copies of Santarus’ filings with the SEC may be obtained free of charge at the “Investors” section of Santarus’ website at www.santarus.com.

SANTARUS’ STOCKHOLDERS ARE ADVISED TO READ THE SCHEDULE TO AND THE SCHEDULE 14D-9, AS EACH MAY BE AMENDED OR SUPPLEMENTED FROM TIME TO TIME, AND ANY OTHER RELEVANT DOCUMENTS FILED WITH THE SEC WHEN THEY BECOME AVAILABLE BEFORE THEY MAKE ANY DECISION WITH RESPECT TO THE OFFER, BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT THE PROPOSED TRANSACTION AND THE PARTIES THERETO.

Item 5. Interest in Securities of the Issuer.

(a)—(b) Other than those shares of Common Stock that may be deemed to be beneficially owned by operation of the Support Agreement, the Reporting Persons do not beneficially own any shares of Common Stock. As a result of the Support Agreement, the Reporting Persons may be deemed to possess shared voting power to vote up to 6,236,082 shares of Common Stock against certain matters described in Item 4 above, and thus, each Reporting Person may be deemed to be the beneficial owner of up to 6,236,082 shares of Common Stock. All shares of Common Stock that may be deemed to be beneficially owned by the Reporting Persons constitute approximately 8.6 percent of the outstanding shares of Common Stock as of November 7, 2013 (after giving effect to the exercise of options to purchase 5,256,309 shares of Common Stock held by the Supporting Stockholders that are exercisable within 60 days of November 7, 2013).

As described in Item 4, the Support Agreement permits any Supporting Stockholder to sell such stockholder’s Subject Shares under a Rule 10b5-1 Plan. The Reporting Persons have been advised that, pursuant to this provision and in accordance with Rule 10b5-1 Plans, since the date of the Support Agreement, a total of 71,809 shares of Common Stock issued upon the exercise of stock options have been sold by the Supporting Stockholders. As a result of such sales, as of November 15, 2013, an aggregate of 6,247,472 shares of Common Stock, representing approximately 8.6 percent of the 67,234,002 outstanding shares of Common Stock as of November 15, 2013 (after giving effect to the deemed exercise of options to purchase 5,267,699 shares of Common Stock held by the Supporting Stockholders that are exercisable on November 15, 2013 or that will become exercisable within 60 days thereafter), are beneficially owned by the Supporting Stockholders.

The Reporting Persons (i) are not entitled to any rights as a stockholder of Santarus as to the shares of Common Stock covered by the Support Agreement, except as otherwise expressly provided in the Support Agreement and (ii) disclaim all beneficial ownership of such shares of Common Stock as permitted by Rule 13d-4 under the Exchange Act. Except as set forth in this Item 5(a)–(b), none of the Reporting Persons and, to the best knowledge of the Reporting Persons, no person named in Schedule A beneficially owns any shares of Common Stock.

(c) Except as described in this Schedule 13D, there have been no transactions in shares of Common Stock effected by any of the Reporting Persons, or, to the best knowledge of the Reporting Persons, any person named in Schedule A, during the past 60 days.

(d) Other than the Supporting Stockholders, to the best knowledge of the Reporting Persons, none of the Reporting Persons nor any of their respective executive officers and directors named in Schedule A has or knows any other person who has the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, any shares of Common Stock beneficially owned by the Reporting Persons.

(e) Not applicable.

Item 6. Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer.

The information set forth under Item 3, Item 4 and Item 5 and the agreements set forth on the Exhibits attached hereto are incorporated herein by reference. Other than the agreements described in this Schedule 13D, to the best knowledge of the Reporting Persons, there are no contracts, arrangements, understandings or relationships (legal or otherwise) among any of the Reporting Persons or any person listed in Schedule A, or between any such person and any other person, with respect to any securities of Santarus,

including, but not limited to, transfer or voting of any of the securities, finder’s fees, joint ventures, loan or option arrangements, puts or calls, guarantees of profits, division of profits or loss, or the giving or withholding of proxies, including any securities pledged or otherwise subject to a contingency the occurrence of which would give another person voting power or investment power over such securities other than standard default and similar provisions contained in loan agreements.

Item 7. Material to Be Filed as Exhibits.

SIGNATURES

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date: November 15, 2013

SCHEDULE A

Directors and Executive Officers of Parent. The following table sets forth the name and present principal occupation or employment for each director and executive officer of Parent. The current business address of each person is 8510 Colonnade Center Drive, Raleigh, North Carolina 27615 and the current telephone number is (919) 862-1000. Each director and executive officer of Parent is a citizen of the United States of America.

Directors and Executive Officers of Intermediary. The following table sets forth the name and present principal occupation or employment for each director and executive officer of Intermediary. The current business address of each person is 8510 Colonnade Center Drive, Raleigh, North Carolina 27615 and the current telephone number is (919) 862-1000. Each director and executive officer of Intermediary is a citizen of the United States of America.

Directors and Executive Officers of Merger Sub. The following table sets forth the name and present principal occupation or employment for each director and executive officer of Merger Sub. The current business address of each person is 8510 Colonnade Center Drive, Raleigh, North Carolina 27615 and the current telephone number is (919) 862-1000. Each director and executive officer of Merger Sub is a citizen of the United States of America.

Exhibit 1

JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended, the undersigned hereby (i) agree to the joint filing with all other Reporting Persons (as such term is defined in the statement on Schedule 13D described below) of a statement on Schedule 13D (including amendments thereto) with respect to the common stock, par value $0.0001 per share, of Santarus, Inc. and (ii) agree that this Agreement be included as an Exhibit to such joint filing. This Agreement may be executed in any number of counterparts all of which taken together shall constitute one and the same instrument.

November 15, 2013

Exhibit 2

JEFFERIES FINANCE LLC

520 Madison Avenue

New York, New York 10022

CONFIDENTIAL

November 7, 2013

COMMITMENT LETTER

Salix Pharmaceuticals, Ltd.

8510 Colonnade Center Drive

Raleigh, North Carolina 27615

Attention: Carolyn Logan, President and Chief Executive Officer

Ladies and Gentlemen:

You have advised Jefferies Finance LLC (“Jefferies Finance”, “we” or “us”) that Salix Pharmaceuticals, Ltd., a Delaware corporation (the “Acquiror” or “you”), intends to (i) acquire (the “Acquisition”) all of the issued and outstanding capital stock of Santarus, Inc., a Delaware corporation (the “Target” and, together with its subsidiaries, the “Acquired Business”), and (ii) concurrently with the consummation of the Acquisition, refinance (including the payment of any applicable prepayment premium or fee, the termination of the commitments thereunder, and the release of all guarantees and security in respect thereof) the existing indebtedness (the “Existing Debt”) of the Acquired Business consisting of outstanding loans and commitments pursuant to that certain Amended and Restated Loan and Security Agreement, dated as of July 11, 2008, between the Target and Comerica Bank as amended (the “Refinancing”). We understand that the Acquisition will be effected in a transaction pursuant to which the Acquiror, or a wholly-owned domestic subsidiary thereof, shall form a new direct or indirect wholly-owned subsidiary organized under the laws of Delaware (“MergerCo”) which will acquire, in a negotiated transaction, 100% of the issued and outstanding shares of capital stock of the Target by way of (x) a cash tender offer (the “Tender Offer”) for any and all of the shares of common stock of the Target (the “Shares”), subject to satisfaction of the Minimum Tender Condition (as defined below), and (y) on the Closing Date (as defined below), a merger of MergerCo with and into the Target (the “Merger”) in accordance with the Merger Agreement (as defined on Exhibit D hereto), with the Target, as the surviving corporation of the Merger, to be an indirect wholly-owned subsidiary of the Acquiror.

As used herein, the term “Minimum Tender Condition” means that a majority of the fully diluted Shares have been validly tendered and delivered for purchase (and not withdrawn) pursuant to the Tender Offer prior to the expiration of the Tender Offer and that, on the Closing Date, a majority of the fully diluted Shares have been purchased by MergerCo pursuant to the Tender Offer.

Capitalized terms used but not defined herein and defined in any exhibit hereto have the meanings assigned to them in such exhibit.

You have advised us that the total purchase price for the Acquisition (including fees, commissions and expenses and the Refinancing) (the “Purchase Price”) will be financed from the following sources:

(i) no borrowings under a $150.0 million senior secured first lien revolving credit facility having the terms set forth in Exhibit A hereto (the “Revolving Credit Facility”),

(ii) $1,200.0 million of borrowings under a senior secured first lien term loan facility having the terms set forth in Exhibit A hereto (the “Senior Term Loan Facility” and, together with the Revolving Credit Facility, the “Senior Credit Facilities”),

(iii) the issuance and sale (the “Notes Offering”) of Senior Unsecured Notes (the “Notes”) yielding gross proceeds of $750.0 million (or, if the offering of the Notes is not consummated prior to, or concurrently with, the Acquisition, the drawdown of senior unsecured increasing rate loans (the “Bridge Loans”) under a senior unsecured bridge loan facility having the terms set forth in Exhibits B and C hereto (the “Bridge Loan Facility” and, together with the Senior Credit Facilities, the “Facilities”) in an aggregate principal amount of $750.0 million), and

(iv) at least $850.0 million of existing unrestricted cash on the balance sheet of the Acquiror (the “Existing Acquiror Cash”).

The transactions described in clauses (i) through (iii) above are referred to as the “Debt Financing” and, together with the Acquisition (including the Tender Offer and the Merger) and the Refinancing and the payment of all related fees, commissions and expenses are collectively referred to herein as the “Transactions.” You and your subsidiaries (and, following the Acquisition, the Target and its subsidiaries) are collectively referred to herein as the “Company.” As used in this Commitment Letter and the other Debt Financing Letters (as defined below), the words “include,” “includes” and “including” shall be deemed to be followed by the phrase “without limitation.”

1. The Commitments.

We are pleased to inform you that we hereby commit, directly or through one or more of our affiliates, to provide the entire principal amount of the Facilities.

The commitments described in this Section 1 are collectively referred to herein as the “Commitments.” Our Commitments are, in each case, on the terms and subject to the conditions set forth in (i) this letter (including the exhibits, schedules and annexes hereto, collectively, this “Commitment Letter”), (ii) the fee letter, dated the date hereof (the “General Fee Letter”), between you and us, (iii) the agency fee letter, dated the date hereof, between you and Jefferies Finance (the “Agency Fee Letter” and, together with the General Fee Letter, the “Fee Letters”) and (iv) the engagement letter, dated the date hereof (together with any exhibits, schedules and annexes thereto, collectively, the “Engagement Letter” and, together with this Commitment Letter and the Fee Letters, the “Debt Financing Letters”), between you and Jefferies LLC (“Jefferies”). Notwithstanding anything to the contrary in any Debt Financing Letter, the terms of this Commitment Letter are intended as an outline of certain of the material provisions of the Facilities, but do not include all of the terms, covenants, representations, warranties, default clauses and other provisions that will be contained in the definitive documents relating to the Debt Financing, which shall be prepared by our counsel (collectively, the “Definitive Debt Documents”); provided that there shall be no closing condition contained in the Definitive Debt Documents that is not specifically set

2

forth in Section 3 hereof, on Exhibit A or B to this Commitment Letter under the heading “Conditions Precedent to Initial Borrowing” or on Exhibit D to this Commitment Letter. Those matters that are not covered or made clear in the Debt Financing Letters are subject to mutual agreement of the parties hereto. No party hereto has been authorized by us to make any oral or written statements or representations that are inconsistent with the Debt Financing Letters.

2. Titles and Roles. As consideration for the Commitments, you agree that you hereby retain and will cause your subsidiaries to retain us or one or more of our designated affiliates (including Jefferies) to act as the sole administrative agent, sole collateral agent, sole book-runner, sole lead arranger, sole underwriter, sole initial purchaser, sole placement agent and sole syndication agent for you and your affiliates in connection with the Facilities and the Notes Offering as more fully set forth herein, in the Fee Letters and in the Engagement Letter, and, except as provided in the immediately succeeding paragraph, no other titles shall be awarded and no compensation (other than that expressly contemplated by the Debt Financing Letters) shall be paid in connection with the Facilities, unless mutually agreed.

We shall have the right, subject to your consent (not to be unreasonably withheld, delayed or conditioned), to appoint additional arrangers, agents, book-runners or managers for the Facilities and award such arrangers, agents, book-runners or managers titles in a manner and with economics determined by us in consultation with you (any such additional arranger, agent, book-runner or manager, an “Additional Agent”) (it being understood that, to the extent we appoint Additional Agents, the economics and commitments of Jefferies Finance in respect of the respective Facilities will be reduced by the amount of the economics allocated to, and the commitment amounts of, such Additional Agents (or their affiliates), in each case upon (and as set forth in) the execution and delivery by such Additional Agent, us and you of customary joinder documentation reasonably acceptable to us and you; provided that the aggregate commitments of such Additional Agents shall not exceed 30% of the total Commitment. It is understood and agreed that Jefferies Finance will have “lead left” placement on all marketing materials relating to the Facilities and will perform the duties and exercise the authority customarily performed and exercised by it in such role, including acting as sole manager of the physical books.

3. Conditions Precedent. The closing of the Facilities and the making of the initial loans and other extensions of credit under the Facilities on the Closing Date are conditioned upon satisfaction or waiver by us and the Additional Agents, of each of the following conditions: (i) since December 31, 2012, except as set forth in and reasonably apparent from (a) the section of the disclosure letter delivered by the Target to the Acquiror prior to the execution of the Merger Agreement (the “Disclosure Letter”) that corresponds to Section 5.7 of the Merger Agreement (as in effect on the date hereof) (or any other section of the Disclosure Letter if it is reasonably and readily apparent solely from the face of such disclosure that such disclosure is intended to qualify the representation and warranty in Section 5.7 of the Merger Agreement (as in effect on the date hereof)) or (b) disclosures in the Company SEC Reports (as defined in the Merger Agreement (as in effect on the date hereof)) filed with the United States Securities and Exchange Commission after December 31, 2012 and prior to the date of the Merger Agreement (excluding any exhibits thereto, any information in the “Risk Factors” or “Forward-Looking Statements” sections thereof and any other forward-looking statements therein), there shall not have been or occurred any event, condition, change, occurrence or development of a state or circumstances which has had or would reasonably be expected to have, individually or in the aggregate, a Target Material Adverse Effect (as defined below); (ii) the Specified Merger Agreement Representations (as defined below) and the Specified Representations (as defined below) shall be true and correct in all material respects (provided, that any representation and warranty that is qualified as to “materiality,” “material adverse effect” or similar language shall be true and correct in all respects (after giving effect to any such qualification therein)); (iii) with respect to the Senior Credit Facilities, the other conditions expressly set forth in Exhibit A to this Commitment Letter, and with respect to the Bridge Loan Facility, the other conditions expressly set forth in Exhibit B to this Commitment Letter, in each case under the heading “Conditions Precedent to Initial Borrowing”; and (iv) the other conditions referred to on Exhibit D to this Commitment Letter.

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For purposes hereof, “Target Material Adverse Effect” means any event, condition, change, occurrence or development of a state of facts that, individually or in the aggregate with all other events, conditions, changes, occurrences or developments of a state of facts, is or would reasonably be expected to (i) be materially adverse to the business, assets, liabilities (contingent or otherwise), financial condition or results of operations of the Company (for purposes of this paragraph, as defined in the Merger Agreement as in effect on the date hereof) and the Company Subsidiary (for purposes of this paragraph, as defined in the Merger Agreement as in effect on the date hereof), taken as a whole, or (ii) prevent, materially impede or materially delay the consummation of the Transactions (for purposes of this paragraph, as defined in the Merger Agreement as in effect on the date hereof); provided that none of the following shall be deemed themselves, alone or in combination, to constitute a Target Material Adverse Effect, and none of the following shall be considered in determining whether a Target Material Adverse Effect has occurred or would reasonably be expected to occur: (A) changes in any applicable Law (for purposes of this paragraph, as defined in the Merger Agreement as in effect on the date hereof) or GAAP (for purposes of this paragraph, as defined in the Merger Agreement as in effect on the date hereof) or the interpretation thereof, (B) changes generally affecting the national or international economy, the biotechnology or pharmaceutical industry or financial or securities markets, (C) political conditions (or changes in such conditions) or acts of terrorism or war or any similar event (or the escalation or worsening thereof) or natural disasters occurring after the date hereof and involving the United States, (D) any failure, in and of itself, by the Company to meet any internal or published industry analyst projections or forecasts or estimates of revenues or earnings for any period ending on or after the date hereof, or any decline in the market price or change in trading volume of the Company Common Stock (for purposes of this paragraph, as defined in the Merger Agreement as in effect on the date hereof) (it being understood and agreed that the facts and circumstances giving rise to such failure or decline in market price or change in trading volume may be deemed to constitute, and may be taken into account in determining whether there has been, a Target Material Adverse Effect), (E) the initiation of any Proceeding (for purposes of this paragraph, as defined in the Merger Agreement as in effect on the date hereof) against the Company by any Stockholder (for purposes of this paragraph, as defined in the Merger Agreement as in effect on the date hereof) (in its capacity as such) challenging or seeking to restrain or prohibit the consummation of the Transactions, (F) any adverse effect arising from the announcement or pendency of the Transactions (provided that this clause (F) shall not diminish the effect of, and shall be disregarded for purposes of, the representations and warranties contained in Section 5.3(b) of the Merger Agreement (as in effect on the date hereof)) or (G) except for any requirement to operate in the ordinary course of business, any adverse effect arising from any action taken by the Company or the Company Subsidiary that is expressly required by the terms of the Merger Agreement or the failure of the Company or the Company Subsidiary to take any action that the Company and the Company Subsidiary are specifically prohibited by Section 7.1(b) of the Merger Agreement (as in effect on the date hereof) from taking, in each case with respect to clauses (A), (B) and (C), only to the extent that the Company and the Company Subsidiary, taken as a whole, are not disproportionately affected by such changes or events relative to other companies in the biotechnology or pharmaceutical industry.

Notwithstanding anything in the Debt Financing Letters or the Definitive Debt Documents, or any other letter agreement or other undertaking concerning the Debt Financing or the Acquisition to the contrary, (i) the only representations and warranties the accuracy of which shall be a condition to the availability of the Facilities on the Closing Date shall be (A) such of the representations and warranties made by the Target in the Merger Agreement as are material to the interests of the Lenders, but only to the extent that you have (or your applicable subsidiary has) the right to terminate your (or its) obligations under the Merger Agreement or decline to consummate the Acquisition as a result of a breach of such representations and warranties (collectively, the “Specified Merger Agreement Representations”) and

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(B) the Specified Representations and (ii) the terms of the Definitive Debt Documents shall be in a form such that they do not impair availability of the Facilities on the Closing Date if the conditions expressly set forth in this Commitment Letter are satisfied (it being understood that, to the extent any security interest in the Collateral is not or cannot be granted or perfected (other than the grant and perfection of a security interest to the extent that a lien on such Collateral may be perfected (x) by the filing of a financing statement under the Uniform Commercial Code, (y) by the delivery of stock certificates of the Borrower’s domestic subsidiaries together with undated stock powers executed in blank or (z) by the filing of a security agreement on the applicable form with the United States Patent and Trademark Office or the United States Copyright Office) on the Closing Date after your use of commercially reasonable efforts to do so or without undue delay, burden or expense, the granting or perfection of a security interest in such Collateral shall not constitute a condition precedent to the availability of the Facilities on the Closing Date, and instead shall be granted or perfected after the Closing Date pursuant to arrangements to be mutually agreed upon). For purposes hereof, “Specified Representations” means the representations and warranties set forth in the Definitive Debt Documents relating to corporate or other organizational existence, organizational power and authority (as to execution, delivery and performance of the applicable Definitive Debt Documents), the due authorization, execution, delivery and enforceability of the applicable Definitive Debt Documents, solvency of the Acquiror and its subsidiaries on a consolidated basis on the Closing Date after giving effect to the Transactions, no conflicts of the Definitive Debt Documents with charter documents or, except where a violation, either individually or in the aggregate, could not reasonably be expected to have a material adverse effect, applicable laws or regulations, compliance with laws and regulations except where non-compliance, either individually or in the aggregate, could not reasonably be expected to have a material adverse effect, Federal Reserve margin regulations, the FCPA, the Patriot Act, OFAC/AML, the Investment Company Act and, subject to permitted liens and the limitations set forth in the immediately preceding sentence, the creation, validity, perfection and priority of security interests. This paragraph shall be referred to herein as the “Certain Funds Provision”.

4. Syndication.

(a) We reserve the right, at any time prior to or after execution of the Definitive Debt Documents, to syndicate all or part of our Commitments to a syndicate of banks, financial institutions and other entities (which may include the Lead Arranger) identified by us in consultation with you (collectively, the “Lenders”); provided that a successful syndication of the Commitments shall not constitute a condition precedent to the availability of the Facilities on the Closing Date. Our Commitments shall be reduced dollar-for-dollar as and when corresponding commitments are received from any Lenders; provided that, other than to the extent provided in the second paragraph of Section 2 hereof in connection with an assignment to an Additional Agent or an assignment to an affiliate of Jefferies Finance, no such reduction shall relieve us of our obligation to fund on the Closing Date the portion of the Commitments so reduced to the extent any Lender fails, upon satisfaction or waiver of all conditions to the initial extensions of credit on the Closing Date, to fund its Commitment on the Closing Date; provided, further, that unless you agree in writing, we and any Additional Agents shall retain exclusive control over the rights and obligations with respect to our Commitments in respect of the Facilities, including all rights with respect to consents, modifications, supplements and amendments, until the Closing Date has occurred. We will exclusively manage all aspects of any syndication in consultation with you and the Additional Agents, including decisions as to the selection of prospective Lenders to be approached, when they will be approached, when their commitments will be accepted, which prospective Lenders will participate, the allocation of the commitments among the Lenders, any naming rights and the amount and distribution of fees to such Lenders. To assist us in our syndication efforts, you agree to prepare and provide (and to use your commercially reasonable efforts to cause the Acquired Business to prepare and provide) promptly to us all customary information with respect to the Acquiror, its subsidiaries, the Acquired Business, the Transactions and the other transactions contemplated hereby,

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including such Projections (defined below) as we may reasonably request in connection with the syndication of the Commitments; provided that, following the consummation of the Acquisition, you shall cause the Acquired Business to prepare and provide us with such information.

(b) We intend to commence our syndication efforts promptly upon your execution of this Commitment Letter, and until the date that is the earlier of (i) 90 days after the Closing Date and (ii) the date on which a Successful Syndication (as defined in the General Fee Letter) is achieved but in no event shall such date be earlier than the Closing Date (the “Syndication Date”), you agree to assist us actively (and to use commercially reasonable efforts to cause the Target actively to assist us) to complete the syndication. Such assistance shall include:

(i) using commercially reasonable efforts to ensure that our efforts benefit materially from your and, to the extent practical or appropriate, the Acquired Business’s existing lending and investment banking relationships,

(ii) direct contact between your senior management, representatives and advisors, on the one hand, and the senior management, representatives and advisors of the proposed Lenders, on the other hand (and (x) prior to the consummation of the Acquisition, your using commercially reasonable efforts to cause, and (y) thereafter, to cause direct contact between senior management, representatives and advisors of the Acquired Business on the one hand, and the senior management, representatives and advisors of the proposed Lenders, on the other hand) at such times and in such places as we may reasonably request,

(iii) your assistance (and (x) prior to the consummation of the Acquisition, your using commercially reasonable efforts to cause, and (y) thereafter, to cause the Acquired Business to assist) in the prompt preparation of one or more confidential information memoranda (each, a “Confidential Information Memorandum”) and other marketing materials to be used in connection with the syndication of our Commitments (together with all Confidential Information Memoranda, the “Materials”),

(iv) the provision to us of copies of any due diligence reports or due diligence memoranda prepared at your direction or at the direction of any of your subsidiaries by legal, accounting, tax or other third party advisors in connection with the Acquisition, subject to the delivery by us to you of customary non-disclosure and non-reliance agreements and releases as shall be reasonably requested: provided, however, that we acknowledge and agree that you shall not be obligated to provide any such reports or memoranda if you are advised by counsel that doing so would constitute a waiver of an attorney client privilege,

(v) your causing us to receive for distribution to the prospective Lenders, at least five business days prior to the Closing Date, a copy of the definitive credit agreement in respect of the Facilities in the form agreed to by you and us,

(vi) your using commercially reasonable efforts to obtain, prior to the commencement of the Required Bank Marketing Period and the Required Notes Marketing Period, (A) a monitored public corporate rating and a monitored public corporate family rating for the Acquiror (pro forma for the Transactions) from each of Standard & Poor’s Ratings Services, a division of the McGraw-Hill Companies, Inc. (“S&P”) and Moody’s Investors Service, Inc. (“Moody’s”), respectively, and (ii) monitored public facility ratings from each of S&P and Moody’s for the Senior Credit Facilities and the Notes (the “Ratings”); provided that the receipt of any such Rating, or the failure to receive a Rating, shall not constitute a condition precedent to the availability of the Facilities on the Closing Date, and

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(vii) the hosting, with us (and to the extent we request that senior management or representatives of the Acquired Business attend, you shall use your commercially reasonably efforts to cause them to attend), of meetings with prospective Lenders at such times and in such places as mutually agreed upon.

(c) You agree, at our request, to assist in the preparation of a version of any Materials consisting exclusively of information and documentation that is either (i) publicly available or (ii) not material with respect to the Company, their affiliates or any of its or their securities for purposes of United States federal and state securities laws (such Materials, “Public Information”). In addition, you agree that, unless specifically labeled “Private – Contains Non-Public Information,” not to disseminate Materials to potential Lenders in connection with the syndication of the Facilities, whether through an Internet website, electronically, in presentations, at meetings or otherwise, that contains any Material Non-Public Information (as defined below). Any information and documentation that is not Public Information is referred to herein as “Material Non-Public Information.” It is understood that in connection with your assistance described above, authorization letters will be included in any information package and presentation whereby you authorize the distribution of such information to prospective Lenders, it being understood that the authorization letter for Public Information shall contain a representation by you to the Lenders that the Public Information does not include any such Material Non-Public Information and each letter shall contain a customary “10b-5” representation. You acknowledge and agree that the following documents contain and shall contain solely Public Information: (i) drafts and final Definitive Debt Documents and marketing term sheets with respect to the Facilities; (ii) administrative materials prepared by us for prospective Lenders (including a lender meeting invitation, Lender allocations, if any, and funding and closing memoranda); and (iii) notification of changes in the terms of the Facilities. If reasonably requested by us, you shall identify Public Information by clearly and conspicuously marking the same as “PUBLIC”.

(d) You agree that all Materials and Information (as defined below) (including draft and execution versions of the Definitive Debt Documents and draft or final offering materials relating to contemporaneous or prior securities issuances by the Company) may be disseminated in accordance with our standard syndication practices (including through hard copy and via one or more internet sites (including an IntraLinks, SyndTrak or similar workspace), e-mail or other electronic transmissions). Without limiting the foregoing, you authorize, and will obtain contractual undertakings from the Acquired Business to authorize, the use of your and its respective logos in connection with any such dissemination, subject to such limitations as are set forth in, or imposed by the Target pursuant to, Section 7.18(c) of the Merger Agreement (as in effect on the date hereof). You further agree that, at our expense, we may place advertisements in financial and other newspapers and periodicals or on a home page or similar place for dissemination of information on the Internet or worldwide web as we may choose, and circulate similar promotional materials, after the closing of the Transactions in the form of a “tombstone” or otherwise, containing information customarily included in such advertisements and materials, including (i) the names of the Company and its subsidiaries (or any of them), (ii) our and our affiliates’ titles and roles in connection with the Transactions, and (iii) the amount, type and closing date of such Transactions.

5. Information. You represent, warrant and covenant (and, as to matters with respect to the Acquired Business, to the best of your knowledge) that:

(a) all written information and data, other than the Projections and information of a general economic or industry-specific nature (the “Information”) that has been or will be made available to us by you, the Target or any of your or their respective representatives, taken as a whole, is or will be, when furnished, complete and correct in all material respects and did not or will not, when furnished, contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements contained therein not misleading in light of the circumstances under which such statements are made, and

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(b) all financial projections that have been or will be made available to us by you or any of your representatives (collectively, the “Projections”) have been or will be prepared in good faith based upon (i) accounting principles consistent with the most recent historical audited financial statements of the Acquiror or the Acquired Business, as the case may be, and (ii) assumptions that are believed by you in good faith to be reasonable at the time made and at the time the related Projections are made available to us (it being understood that any such Projections are subject to uncertainties and contingencies, some of which are beyond your control, that no assurance can be given that any particular Projections will be realized, that actual results may differ, and that such differences may be material).

You agree that, if at any time prior to the later of the Closing Date and the Syndication Date, you become aware that any of the representations and warranties in the preceding sentence would be incorrect in any material respect if the Information or Projections were then being furnished and such representations and warranties were then being made, you shall supplement promptly such Information and/or Projections, as the case may be, in order that such representations and warranties will be correct in all material respects.

You shall be solely responsible for Information and the Projections. We (i) will be relying on Information and the Projections without having independently verified the accuracy or completeness of the same, (ii) do not assume responsibility for the accuracy or completeness of any such Information and Projections and (iii) will not make an appraisal of your assets or liabilities or those of the Acquired Business. You shall, in connection with our activities on your behalf, (i) furnish us with all Information and data that we may reasonably request and (ii) provide us full access, as reasonably requested, to your officers, directors, employees and professional advisors and use commercially reasonable efforts to provide us full access, as reasonably requested, to those of the Acquired Business; provided that, following the consummation of the Acquisition, you shall cause the Acquired Business to provide us full access, as reasonably requested, to such persons or entities.

6. Clear Market. You agree that, from the date hereof until the earlier of (a) the date on which a Successful Syndication has been achieved, provided that such date shall not be earlier than the Closing Date and (b) the date that is 90 days after the Closing Date, you will not, you will not permit your subsidiaries, representatives and advisors to, and you will use commercially reasonable efforts to cause the Acquired Business not to, directly or indirectly, (i) syndicate, place, sell or issue, (ii) attempt or offer to syndicate, place, sell or issue, (iii) announce or authorize the announcement of the syndication, placement, sale or issuance of, or (iv) engage in discussions concerning the syndication, placement, offering, sale or issuance of, any debt facility, or debt, equity-linked or equity security of you, the Acquired Business or any of your or its respective affiliates (other than (i) the Debt Financing contemplated hereby and the Notes Offering and (ii) debt permitted to be incurred by the Acquired Business under the Merger Agreement (as in effect on the date hereof)), including any renewals or refinancings of any existing debt facility, without our prior written consent, which may be given or withheld in our sole discretion.

7. Fees and Expenses. As consideration for the Commitments and our other undertakings hereunder, you hereby agree to pay or cause to be paid to us and Jefferies for our respective accounts (and, to the extent entitled thereto, the respective accounts of any Additional Agents) the fees, expenses and other amounts set forth in the Debt Financing Letters.

8. Indemnification and Waivers. As consideration for the Commitments and our other undertakings hereunder, you agree to the provisions with respect to indemnification, waivers and other matters contained in Annex A hereto, which is hereby incorporated by reference in this Commitment Letter.

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9. Confidentiality. This Commitment Letter is delivered to you on the understanding that neither the existence of this Commitment Letter or any other Debt Financing Letter nor any of their terms or substance will be disclosed by you, directly or indirectly, to any other person or entity except (a) in any legal, judicial, administrative proceeding or other compulsory process or otherwise as required by any applicable law rule or regulation (in which case you agree to inform us promptly thereof (to the extent practicable and you are lawfully permitted to do so) and to cooperate with us in securing a protective order (at your cost and expense) in respect thereof to the extent we are lawfully permitted to do so), (b) to your officers, directors, employees, attorneys, accountants, representatives and advisors on a confidential and need-to-know basis, (c) this Commitment Letter may be disclosed (but not the Fee Letters) to rating agencies in connection with their review of the Facilities, the Notes, the Acquiror or the Target, (d) the information contained in this Commitment Letter (but not that contained in the Fee Letters) may be disclosed in any Confidential Information Memorandum or in connection with the syndication of the Facilities or the Notes Offering, and (e) this Commitment Letter and the General Fee Letter (but not the Agency Fee Letter or the Engagement Letter) may be disclosed to the Acquired Business and its officers, directors, employees, attorneys, accountants, representatives and advisors, in each case on a confidential and reasonable need-to-know basis and only in connection with the Transactions; provided, that the disclosure of the Fee Letters or the contents to the Acquired Business or any of its officers, directors, employees, attorneys, accountants and advisors shall be redacted in a manner reasonably satisfactory to us. Notwithstanding the foregoing, this Commitment Letter (but not any other Debt Financing Letter) may be filed with the Securities and Exchange Commission or any other regulatory agency as required by applicable law and regulations. You may also disclose, on a confidential basis, the aggregate amount of fees payable under the Fee Letters as part of a generic disclosure regarding sources and uses (but without disclosing any specific fees set forth therein) in connection with the syndication of the Facilities and/or the Notes Offering.

We, the Additional Agents and our and their affiliates shall use all non-public information received by us and them from you, the Target or your or its respective subsidiaries and representatives in connection with the Transactions solely for the purposes of providing the services contemplated by the Debt Financing Letters and shall treat confidentially all such non-public information; provided, however, that nothing herein shall prevent us from disclosing any such information (a) on a customary basis, to Moody’s and S&P in connection with obtaining the Ratings in connection with the Transactions, (b) subject to the further proviso below in this paragraph, to any Additional Agents, Lenders or participants or prospective Additional Agents, Lenders or participants and to any direct or indirect contractual counterparty to any credit default swap or similar derivative product, (c) in any legal, judicial, administrative proceeding or other compulsory process or otherwise as required by applicable law, rule or regulation (in which case we will promptly notify you to the extent practicable and we are permitted by law, rule or regulation to do so and to cooperate with you (at your cost and expense) in securing a protective order in respect thereof to the extent you are lawfully permitted to do so, except in connection with any request as part of any regulatory audit or examination conducted by our or our affiliates’ accountants or any governmental regulatory authority exercising examination or regulatory authority over us or our affiliates), (d) upon the request or demand of any governmental or regulatory authority having jurisdiction over us or our affiliates or upon the good faith determination by our counsel that such information should be disclosed in light of ongoing oversight or review by any governmental or regulatory authority having jurisdiction over us or our affiliates (in which case we shall, to the extent practicable and permitted by law, rule or regulation, except with respect to any audit or examination conducted by accountants or any governmental regulatory authority exercising examination or regulatory authority, promptly notify you and cooperate with you (at your cost and expense) in securing a protective order in respect thereof to the extent you are lawfully permitted to do so), (e) to the officers, directors,

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employees, legal counsel, independent auditors, professionals and other experts or agents of us working on the Transactions (collectively, “Representatives”) on a reasonable need-to-know basis in connection with the Transactions and who are informed of the confidential nature of such information and are or have been advised of their obligation to keep such information confidential, and we shall be responsible for our Representatives’ compliance with this paragraph, (f) to any of our affiliates and Representatives of our affiliates on a reasonable need-to-know basis in connection with the Transactions and who are informed of the confidential nature of such information and are or have been advised of their obligation to keep such information as confidential, and we shall be responsible for our affiliates’ and our affiliates’ Representatives’ compliance with this paragraph) solely in connection with the Transactions, (g) to the extent any such information is or becomes publicly available other than by reason of improper disclosure by us, our affiliates or our or their Representatives in breach of this Commitment Letter, (h) to the extent that any such information is independently developed by us, any of our affiliates or any of our or their Representatives, (i) to the extent that such information is received by us or our affiliates from a third party that is not to our or our affiliate’s knowledge subject to confidentiality obligations to you or the Target and (j) to establish a “due diligence” defense, if applicable; provided, further, that the disclosure of any such information to any Additional Agents or Lenders or prospective Additional Agents or Lenders or participants or prospective participants and to any direct or indirect contractual counterparty to any credit default swap or similar derivative product referred to above shall be made subject to the acknowledgment and acceptance by such Additional Agents or Lenders or prospective Additional Agents or Lenders or participant or prospective participant or such direct or indirect contractual counterparty to any credit default swap or similar derivative product that such information is being disseminated on a confidential basis (on substantially the terms set forth in this paragraph or as is otherwise reasonably acceptable to you and us, including, without limitation, as agreed in any Confidential Information Memorandum or other marketing materials) in accordance with our standard syndication processes or customary market standards for dissemination of such type of information. Our and our affiliates’ obligations under this paragraph shall automatically terminate and be superseded by the confidentiality provisions in the Definitive Debt Documents upon the execution and delivery of the Definitive Debt Documents and initial funding thereunder (or, in the event that any Notes are issued on the Closing Date, upon the initial funding of the Senior Credit Facilities only); provided that such confidentiality provisions are no less comprehensive in their scope in any material respect than the confidentiality provisions of this Commitment Letter, or shall expire on the second anniversary of the date hereof.

Notwithstanding anything herein to the contrary, you and we (and any of your and our respective employees, representatives or other agents) may disclose to any and all persons, without limitation of any kind, the tax treatment and tax structure of the transactions contemplated by the Debt Financing Letters and all materials of any kind (including opinions or other tax analyses) that are provided to you or us relating to such tax treatment and tax structure, except that (i) tax treatment and tax structure shall not include the identity of any existing or future party (or any affiliate of such party) to any Debt Financing Letter, and (ii) neither you nor we shall disclose any information relating to such tax treatment and tax structure to the extent nondisclosure is reasonably necessary in order to comply with applicable securities laws. For this purpose, the tax treatment of the transactions contemplated by the Debt Financing Letters is the purported or claimed U.S. federal income tax treatment of such transactions and the tax structure of such transactions is any fact that may be relevant to understanding the purported or claimed U.S. federal income tax treatment of such transactions.

10. Conflicts of Interest; Absence of Fiduciary Relationship. You acknowledge and agree that:

(a) We and/or our affiliates and subsidiaries (including Jefferies Group LLC and its affiliates, the “Jefferies Group”), in our and their respective capacities as principal or agent are involved in a wide range of commercial banking and investment banking activities globally (including investment

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advisory, asset management, research, securities issuance, trading, and brokerage) from which conflicting interests or duties may arise and, therefore, conflicts may arise between (i) our interests and duties hereunder and (ii) the duties or interests of another member of the Jefferies Group;

(b) We and any other member of the Jefferies Group may, at any time, (i) provide services to any other person, (ii) engage in any transaction (on our or its own account or otherwise) with respect to you or any of your subsidiaries or affiliates or (iii) act in relation to any matter for any other person whose interests may be adverse to you or any of your subsidiaries or affiliates (a “Third Party”), and may retain for our or its own benefit any related remuneration or profit, notwithstanding that a conflict of interest exists or may arise and/or any member of the Jefferies Group is in possession or has come or comes into possession (whether before, during or after the consummation of the transactions contemplated hereunder) of information confidential to you; provided that such confidential information shall not be used by us or any other member of the Jefferies Group in performing services or providing advice to any Third Party or in violation of the provisions of Section 9 hereof. You accept that permanent or ad hoc arrangements/information barriers may be used between and within our divisions or divisions of other members of the Jefferies Group for the purposes described in this clause (b) and that locating directors, officers or employees in separate workplaces is not necessary for such purpose;

(c) Information that is held elsewhere within us or the Jefferies Group, but of which none of the individual directors, officers or employees having material responsibilities for the consummation of the transactions contemplated by this Commitment Letter actually has knowledge (or can properly obtain knowledge without breach of internal procedures), shall not for any purpose be taken into account in determining our responsibilities to you hereunder;

(d) Neither we nor any other member of the Jefferies Group shall have any duty to disclose to you, or utilize for your benefit, any non-public information acquired in the course of providing services to any other person, engaging in any transaction (on our or its own account or otherwise) or otherwise carrying on our or its business;

(e) (i) Other then as expressly provided for in that certain Engagement Letter, dated August 20, 2013, between Salix Pharmaceuticals, Inc. and Jefferies, neither we nor any of our affiliates have assumed any advisory responsibility or any other obligation in favor of the Acquiror or any of its affiliates except the obligations expressly provided for under the Debt Financing Letters, (ii) we and our affiliates, on the one hand, and the Acquiror and its affiliates, on the other hand, have an arm’s-length business relationship that does not directly or indirectly give rise to, nor does the Acquiror or any of its affiliates rely on, any fiduciary duty on the part of us or any of our affiliates and (iii) we are (and are affiliated with) full service financial firms and as such may effect from time to time transactions for our own account or the account of customers, and hold long or short positions in debt, equity-linked or equity securities or loans of companies that may be the subject of the transactions contemplated by this Commitment Letter (and, in particular, we and any other member of the Jefferies Group may at any time hold debt or equity securities for our or its own account in the Acquiror). With respect to any securities and/or financial instruments so held by us, any of our affiliates or any of our respective customers, all rights in respect of such securities and financial instruments, including any voting rights, will be exercised by the holder of such rights, in its sole discretion. You hereby waive and release, to the fullest extent permitted by law, any claims you have, or may have, with respect to (i) any breach or alleged breach of fiduciary duty (and agree that we shall have no liability (whether direct or indirect) to you in respect of such a fiduciary duty claim or to any person asserting a fiduciary duty claim on behalf of or in right of you, including your stockholders, employees or creditors) and (ii) any conflict of interest arising from such transactions, activities, investments or holdings, or arising from our failure or the failure of any of our affiliates to bring such transactions, activities, investments or holdings to your attention; and

11

(f) Neither we nor any of our affiliates are advising you as to any legal, tax, investment, accounting or regulatory matters in any jurisdiction. You shall consult with your own advisors concerning such matters and shall be responsible for making your own independent investigation and appraisal of the transactions contemplated by the Debt Financing Letters, and neither we nor our affiliates shall have responsibility or liability to you with respect thereto. Any review by us of the Acquiror, the Target, their respective subsidiaries and affiliates, the Transactions, the other transactions contemplated by the Debt Financing Letters or other matters relating to such transactions will be performed solely for our benefit and shall not be on behalf of you or any of your affiliates.

11. Choice of Law; Jurisdiction; Waivers. The Debt Financing Letters, and any claim, controversy or dispute arising under or related to the Debt Financing Letters (whether based upon contract, tort or otherwise), shall be governed by, and construed in accordance with, the laws of the State of New York without regard to conflict of law principles (other than sections 5-1401 and 5-1402 of the New York General Obligations Law), except that (i) the interpretation of definition of “Target Material Adverse Effect” as used in this Commitment Letter and the determination of whether a Target Material Adverse Effect has occurred and (ii) the determination of the accuracy of the Specific Merger Agreement Representations and whether as the result of any inaccuracy thereof you or the Target have the right to terminate your or its obligations under the Merger Agreement, in each case shall be governed by, and construed in accordance with the laws of the State of Delaware, without regard to the principles of conflicts of laws. To the fullest extent permitted by applicable law, you hereby irrevocably submit to the exclusive jurisdiction of any New York State court or federal court sitting in the County of New York and the Borough of Manhattan in respect of any claim, suit, action or proceeding arising out of or relating to the provisions of the Debt Financing Letters and irrevocably agree that all claims in respect of any such claim, suit, action or proceeding may be heard and determined in any such court and that service of process therein may be made by certified mail, postage prepaid, to your address set forth above. You and we hereby waive, to the fullest extent permitted by applicable law, any objection that you or we may now or hereafter have to the laying of venue of any such claim, suit, action or proceeding brought in any such court, and any claim that any such claim, suit, action or proceeding brought in any such court has been brought in an inconvenient forum. You and we hereby waive, to the fullest extent permitted by applicable law, any right to trial by jury with respect to any claim, suit, action or proceeding (whether based upon contract, tort or otherwise) arising out of or relating to the Debt Financing Letters, any of the Transactions or any of the other transactions contemplated hereby or thereby. Without limiting your rights under (and to the extent provided in) this Commitment Letter, neither you nor any of your subsidiaries or affiliates shall be entitled to any recovery, judgment or damages of any kind, including consequential, indirect or punitive damages, against any Debt Financing Source Party (as defined in the Merger Agreement as in effect on the date hereof), whether at law, in equity, in contract, in tort or otherwise in connection with the Merger Agreement or the Transactions (as defined in the Merger Agreement as in effect on the date hereof). The provisions of this Section 11 are intended to be effective upon the execution of this Commitment Letter without any further action by you, and the introduction of a true copy of this Commitment Letter into evidence shall be conclusive and final evidence as to such matters.

12. Miscellaneous.

(a) This Commitment Letter may be executed in two or more counterparts, each of which will be deemed an original, but all of which taken together will constitute one and the same instrument. Delivery of an executed signature page of this Commitment Letter by facsimile, PDF or other electronic transmission will be effective as delivery of a manually executed counterpart hereof.

(b) You may not assign any of your rights, or be relieved of any of your obligations, under this Commitment Letter without our prior written consent, which may be given or withheld in our sole discretion (and any purported assignment without such consent, at our sole option, shall be null and

12

void). We may at any time and from time to time assign all or any portion of our Commitments hereunder to one or more of our affiliates, to one or more Lenders as part of any syndication of the Facilities or as contemplated by Section 2 or Section 4 hereof or as permitted by the Definitive Debt Documents, whereupon we shall be released from the portion of our Commitments hereunder so assigned; provided that, other than in connection with an assignment to an affiliate of Jefferies Finance as contemplated by Section 4 hereof or as contemplated by the second paragraph of Section 2, such assignment shall not relieve us of our obligation to fund on the Closing Date the portion of our Commitments so assigned to the extent such assignee fails, upon satisfaction or waiver by us of all conditions to the initial extensions of credit on the Closing Date, to fund such assigned Commitments on the Closing Date. Any and all obligations of, and services to be provided by, us hereunder (including the Commitments) may be performed, and any and all of our rights hereunder may be exercised, by or through any of our affiliates or branches and we reserve the right to allocate, in whole or in part, to our affiliates or branches certain fees payable to us in such manner as we and our affiliates may agree in our and their sole discretion. You further acknowledge that we may, subject to the provisions of Section 9 hereof, share with any of our affiliates, and such affiliates may share with us, any information relating to the Transactions, you or the Acquired Business (and your and their respective affiliates), or any of the matters contemplated in the Debt Financing Letters.

(c) This Commitment Letter has been and is made solely for the benefit of you, us and the indemnified persons (as defined in Annex A hereto) and your, our and their respective successors and assigns, and nothing in this Commitment Letter, expressed or implied, is intended to confer or does confer on any other person or entity any rights or remedies under or by reason of this Commitment Letter or your and our agreements contained herein.

(d) The Debt Financing Letters set forth the entire understanding of the parties hereto as to the scope of the Commitments and our obligations hereunder and thereunder. The Debt Financing Letters supersede all prior understandings and proposals, whether written or oral, between us and you relating to any financing or the transactions contemplated hereby and thereby.

(e) You agree that we or any of our affiliates may disclose non-confidential information about the Transactions to market data collectors and similar service providers to the financing community.

(f) We hereby notify you that pursuant to the requirements of the USA PATRIOT Improvement and Reauthorization Act, Pub. L. 109-177 (signed into law March 9, 2006) (as amended from time to time, the “Patriot Act”), we, each Additional Agent and each Lender may be required to obtain, verify and record information that identifies you and the other Credit Parties, which information includes the name, address, tax identification number and other information regarding you and the other Credit Parties that will allow us, such Additional Agent or such Lender to identify you and the other Credit Parties in accordance with the Patriot Act. This notice is given in accordance with the requirements of the Patriot Act and is effective as to us, each Additional Agent and each Lender. You agree that we shall be permitted to share any or all such information obtained by us to satisfy the requirements of the Patriot Act with the Additional Agents and the Lenders.

13. Amendment; Waiver. This Commitment Letter may not be modified or amended except in a writing duly executed by the parties hereto. No waiver by any party of any breach of, or any provision of, this Commitment Letter shall be deemed a waiver of any similar or any other breach or provision of this Commitment Letter at the same or any prior or subsequent time. To be effective, a waiver must be set forth in writing signed by the waiving party and must specifically refer to this Commitment Letter and the breach or provision being waived.

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14. Surviving Provisions. Notwithstanding anything to the contrary in this Commitment Letter: (i) Sections 7 to and including 15 hereof shall survive the expiration or termination of this Commitment Letter, regardless of whether the Definitive Debt Documents have been executed and delivered or the Transactions consummated, and (ii) Sections 2 and 4 to and including 13 hereof shall survive execution and delivery of the Definitive Debt Documents and the consummation of the Transactions.

15. Acceptance, Expiration and Termination. Please indicate your acceptance of the terms of each of the Debt Financing Letters by returning to us executed counterparts thereof not later than 5:00 p.m., New York City time, on November 7, 2013 (the “Deadline”). The Debt Financing Letters are conditioned upon your contemporaneous execution and delivery to us, and the contemporaneous receipt by us, of executed counterparts of each Debt Financing Letter on or prior to the Deadline. This Commitment Letter will expire at the Deadline in the event that you have not returned such executed counterparts to us by such time. Thereafter, except with respect to any provision that expressly survives pursuant to Section 14, this Commitment Letter (but not the other Debt Financing Letters) will terminate automatically on the earliest of (i) the date of termination or abandonment of the Merger Agreement, (ii) the closing of the Acquisition, and (iii) 5:00 p.m., New York City time, on May 7, 2014 (the “Final Termination Date”). In addition, our Commitment hereunder to provide Bridge Loans shall terminate upon the closing of the sale of the Notes (in escrow or otherwise).

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We are pleased to have the opportunity to work with you in connection with this important financing.

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ANNEX A TO COMMITMENT LETTER

INDEMNIFICATION AND WAIVER

Except as otherwise defined in this Annex A, capitalized terms used but not defined herein have the meanings assigned to them elsewhere in this Commitment Letter.

The Acquiror (“you”) hereby agrees (i) to indemnify and hold harmless Jefferies Finance LLC (“we” or “us”), each Additional Agent, our and their respective affiliates and subsidiaries (including Jefferies) and each of their respective officers, directors, partners, trustees, employees, advisors, agents, representatives, attorneys-in-fact, members, successors, assigns and each other person or entity that controls us or any Additional Agent or any of our or their respective affiliates and subsidiaries (each, an “indemnified person”) from and against any and all actions, suits, proceedings (including any investigations or inquiries), claims, losses, damages, liabilities or expenses of any kind or nature whatsoever (collectively, “Losses”) which may be incurred by or asserted against or involve any indemnified person as a result of, arising out of, or in any way related to or resulting from, the Transactions or the Debt Financing Letters or the use of the proceeds thereunder (each, a “Covered Claim”), regardless of whether the indemnified person is a named party thereto or whether such Covered Claim is brought by you, any of your affiliates or a third party and (ii) to reimburse each indemnified person upon demand at any time and from time to time for all reasonable and documented out-of-pocket legal and other expenses incurred by such indemnified person in connection with investigating, preparing to defend or defending, or providing evidence in or preparing to serve or serving as a witness with respect to, any Covered Claim or in connection with any enforcement of the indemnification obligations and waivers set forth in this Annex A; provided, however, that (i) with respect to legal expenses, your obligations shall be limited to one firm of counsel for all such indemnified persons, taken as a whole and, if necessary, of a single local counsel and regulatory counsel in each appropriate jurisdiction (which may include a single special counsel and regulatory counsel acting in multiple jurisdictions) for all such indemnified persons, taken as a whole (and, in the case of an actual or perceived conflict of interest, of another firm of counsel in each applicable jurisdiction for such affected indemnified person) and (ii) no indemnified person will be entitled to indemnity hereunder in respect of (A) any Loss to the extent that it is found by a final, non-appealable judgment of a court of competent jurisdiction that such Loss resulted from (x) the gross negligence, bad faith or willful misconduct of such indemnified person (or any of its subsidiaries, affiliates, officers, directors, partners, trustees, employees, agents, members, successors, assigns or controlling persons), (y) a material breach of the obligations of such indemnified person (or any of its subsidiaries, affiliates, officers, directors or employees) under this Commitment Letter, or (z) any proceeding that does not involve an act or omission by you or any of your affiliates and that is brought by an indemnified person (or any of its subsidiaries, affiliates, officers, directors, partners, trustees, employees, agents, members, successors, assigns or controlling persons) against any other indemnified person (or any of its subsidiaries, affiliates, officers, directors, partners, trustees, employees, agents, members, successors, assigns or controlling persons) (other than any Covered Claim against any indemnified person in its capacity or in fulfilling its role as an agent or arranger or similar role under any Facility) or (B) any settlement of any Covered Claim entered into by any indemnified person without your prior written consent (which consent will not be unreasonably withheld, conditioned or delayed). In addition, in no event will any indemnified person be liable for consequential, special, exemplary, punitive or indirect damages (including any loss of profits, business or anticipated savings), whether, directly or indirectly, as a result of any failure to fund all or any portion of the Debt Financing or otherwise arising out of, relating to, resulting from or otherwise in connection with the Debt Financing or arising out of, relating to, resulting from or otherwise in connection with any Covered Claim or otherwise. In addition, no indemnified person will be liable for any damages arising from the use by unauthorized persons of Information, Projections or other Materials sent through electronic, telecommunications or other information transmission systems that are intercepted or otherwise obtained by such persons.

Annex A-1

You shall not, without our prior written consent (which consent shall not be unreasonably withheld, conditioned or delayed), settle or compromise or consent to the entry of any judgment in or otherwise seek to terminate any pending or threatened Covered Claim in which any indemnified person is or could be a party and as to which indemnification or contribution could have been sought by such indemnified person hereunder whether or not such indemnified person is a party to any Debt Financing Letter, unless (i) the settlement, compromise, consent or termination (A) includes an express unconditional release of such indemnified persons from all Losses, directly or indirectly, arising out of, relating to, resulting from or otherwise in connection with such Covered Claim and (B) does not include any statement as to or any admission of fault, culpability, wrongdoing or a failure to act by or on behalf of such indemnified person.

If for any reason (other than as provided in clauses (x), (y) and (z) of the first paragraph of this Annex A-1) the foregoing indemnity is unavailable to an indemnified person or insufficient to hold an indemnified person harmless, then you to the fullest extent permitted by law, shall contribute to the amount paid or payable by such indemnified person as a result of such Losses in such proportion as is appropriate to reflect the relative benefits received by you, on the one hand, and by us, on the other hand, from the Transactions or, if allocation on that basis is not permitted under applicable law, in such proportion as is appropriate to reflect not only the relative benefits received by you, on the one hand, and us, on the other hand, but also the relative fault of you, on the one hand, and us, on the other hand, as well as any relevant equitable considerations. Notwithstanding the provisions hereof, the aggregate contribution of all indemnified persons to all Losses shall not exceed the amount of fees actually received by us and our affiliates (including Jefferies) pursuant to the Fee Letters and the Engagement Letter. For the purposes of this paragraph, it is hereby further agreed that (i) the relative benefits to you, on the one hand, and us, on the other hand, with respect to the Transactions shall be deemed to be in the same proportion as (x) the total value paid or received or contemplated to be paid or received by you, your equityholders and/or your or their respective affiliates, as the case may be, in the Transactions, whether or not the Transactions are consummated, bears to (y) the fees actually paid to us and Jefferies under the Fee Letters and the Engagement Letter and (ii) the relative fault of you, on the one hand, and us and the Additional Agents, on the other hand, with respect to the Transactions shall be determined by reference to, among other things, whether any untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by you, any of your affiliates and/or any of your or their respective officers, directors, partners, trustees, employees, affiliates, shareholders, advisors, agents, representatives, attorneys-in-fact and controlling persons (collectively, the “Acquiror Group”) or by us, the Additional Agents any of our or their affiliates and/or any of our or their respective officers, directors, partners, trustees, employees, affiliates, shareholders, advisors, agents, representatives, attorneys-in-fact and controlling persons, as well as your and our (and the Additional Agents’) relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission.

In addition, you shall reimburse the indemnified persons for all reasonable and documented expenses (including reasonable fees and expenses of external counsel), as incurred, in connection with investigating, preparing, defending or settling any Covered Claim for which indemnification or contribution may be sought by the indemnified person, whether or not any indemnified person is a named party thereto or whether such Covered Claim is brought by you, any of your affiliates or a third party; provided that, if any such reimbursement relates to a Loss that is found by a final, non-appealable judgment of a court of competent jurisdiction to have resulted from (x) the gross negligence, bad faith or willful misconduct of such indemnified person (or any of its subsidiaries, affiliates, officers, directors,

Annex A-2

partners, trustees, employees, agents, members, successors, assigns or controlling persons) or (y) a material breach of the obligations of such indemnified person (or any of its subsidiaries, affiliates, officers, director, partners, trustees, employees agents, members, successors, assigns or controlling persons) under this Commitment Letter, Jefferies Finance or the respective Additional Agent, as applicable, on behalf of any such indemnified person, shall promptly repay to you the amounts so advanced.

The indemnity, contribution and expense reimbursement obligations set forth herein (i) shall be in addition to any liability you may have to any indemnified person at law, in equity or otherwise, (ii) shall survive the expiration or termination of the Debt Financing Letters (notwithstanding any other provision of any Debt Financing Letter or the Definitive Debt Documents), (iii) shall apply to any modification, amendment, waiver or supplement of our and any of our affiliates’ commitment and/or engagement, (iv) shall remain operative and in full force and effect regardless of any investigation made by or on behalf of us or any other indemnified person and (v) shall be binding on any successor or assign of you or the successor or assign of all or substantially all of your business and assets.

* * *

Annex A-3

EXHIBIT A TO COMMITMENT LETTER

SUMMARY OF TERMS OF SENIOR CREDIT FACILITIES

Set forth below is a summary of certain of the terms of the Senior Credit Facilities and the documentation related thereto. Capitalized terms used and not otherwise defined in this Exhibit A have the meanings set forth elsewhere in this Commitment Letter.

Exhibit A-1

Exhibit A-2

Exhibit A-3

Exhibit A-4

Exhibit A-5

Exhibit A-6

Exhibit A-7

Exhibit A-8

Exhibit A-9

Exhibit A-10

Exhibit A-11

Exhibit A-12

Exhibit A-13

Exhibit A-14

Exhibit A-15

Exhibit A-16

*  *  *

Exhibit A-17

ANNEX A-I TO EXHIBIT A

TO COMMITMENT LETTER

Interest and Certain Fees

Annex A-I-1

*  *  *

Annex A-I-2

EXHIBIT B TO COMMITMENT LETTER

SUMMARY OF TERMS OF THE BRIDGE LOANS

Set forth below is a summary of certain of the terms of the Bridge Loan Facility and the documentation related thereto. Capitalized terms used and not otherwise defined in this Exhibit B have the meanings set forth elsewhere in this Commitment Letter.

Exhibit B-1

Exhibit B-2

Exhibit B-3

Exhibit B-4

Exhibit B-5

Exhibit B-6

Exhibit B-7

*  *  *

Exhibit B-8

EXHIBIT C TO COMMITMENT LETTER

SUMMARY OF TERMS OF TERM LOANS

AND EXCHANGE NOTES

Set forth below is a summary of certain of the terms of the Term Loans and the Exchange Notes and the documentation related thereto. Capitalized terms used and not otherwise defined in this Exhibit C have the meanings set forth elsewhere in this Commitment Letter.

Term Loans

The Term Loans will be governed by the provisions of the Bridge Loan Documents and, except as expressly set forth below, will have the same terms as the Bridge Loans.

Exhibit C-1

Exchange Notes

At any time on or after the Bridge Loan Maturity Date, upon five or more business days’ prior notice, the Term Loans may, at the option of any Lender, be exchanged for a principal amount of Exchange Notes equal to 100% of the aggregate principal amount of the Term Loans so exchanged. The Borrower will issue Exchange Notes under an indenture (the “Indenture”) that complies with the Trust Indenture Act of 1939, as amended. The Borrower will appoint a trustee reasonably acceptable to the Lenders.

Exhibit C-2

*  *  *

Exhibit C-3

EXHIBIT D TO COMMITMENT LETTER

CLOSING CONDITIONS

Capitalized terms used but not defined in this Exhibit D have the meanings assigned to them elsewhere in this Commitment Letter. The closing of the Facilities and the making of the initial loans and other extensions of credit under the Facilities are conditioned upon satisfaction of the conditions precedent contained in Section 3 of this Commitment Letter, which includes the conditions precedent set forth below in this Exhibit D. For purposes of this Exhibit D, references to “we”, “us” or “our” means Jefferies Finance, Jefferies and their respective affiliates.

GENERAL CONDITIONS

1. Concurrent Financings. The Acquiror shall have available Existing Acquiror Cash in the amount required by this Commitment Letter. The Existing Acquiror Cash, together with the proceeds on the Closing Date from the Debt Financing, shall be sufficient to pay the Purchase Price. The Definitive Debt Documents shall be prepared by our counsel, shall be consistent with the Debt Financing Letters (including the respective Exhibits thereto), shall have been executed and delivered by the Credit Parties to the Administrative Agent and otherwise shall be in form and substance reasonably satisfactory to us and the Additional Agents, subject to the Certain Funds Provision. With respect to the Senior Credit Facilities, the Collateral Agent, for the benefit of the Lenders under the Senior Credit Facilities, shall have been granted perfected first priority security interests in all assets of the Credit Parties to the extent described in Exhibit A to this Commitment Letter under the caption “Collateral” in form and substance reasonably satisfactory to the Lead Arranger and the Additional Agents, subject to the Certain Funds Provision.

2. Transactions. The Transactions (including the Acquisition, the Tender Offer and the Merger) shall have been consummated or will be consummated in accordance with the Merger Agreement concurrently with or immediately following the use of the Existing Acquiror Cash, the borrowing of the Senior Term Loans and the Bridge Loans (or the issuance of the Notes in lieu of the Bridge Loans), and the receipt by the Acquiror of the proceeds of the foregoing, and the Target shall have become a wholly-owned direct or indirect subsidiary of the Acquiror. The executed Agreement and Plan of Merger, dated as of November 7, 2013 (together with the annexes, schedules, exhibits and attachments thereto, the “Merger Agreement”), among you, MergerCo and the Target shall not have been amended, modified or waived, and the Acquiror (or its applicable affiliate) shall not have consented to any action thereunder or pursuant thereto which would require the consent of the Acquiror (or its applicable affiliate) under the Merger Agreement, in each case in any manner adverse in any material respect to the interest of the Lenders or the Lead Arranger in their respective capacities as such without the consent of the Lead Arranger and the Additional Agents (it being understood and agreed that any (1) decrease in the purchase price of more than 10% of the purchase price on the date of this Commitment Letter shall be deemed to be a modification which is adverse in a material respect to the interests of the Lenders and the Lead Arranger, (2) decrease in the purchase price of 10% or less of the purchase price on the date of this Commitment Letter shall not be deemed to be a modification which is adverse in a material respect to the Lenders and the Lead Arranger, provided that the amount funded under the Senior Credit Facilities and the Bridge Loans (or the Notes, as the case may be) are reduced on a pro rata basis by the amount of any reduction of the purchase price, (3) increase in such aggregate purchase price shall not be deemed to be a modification which is adverse in a material respect to the Lenders and the Lead Arranger so long as such increase is funded solely by cash of the Acquiror in addition to the Existing Acquiror Cash, (4) change to the definition of “Company Material Adverse Effect” shall be deemed to be adverse to the interest of the Lenders and the Lead Arranger, and (5) any modifications to Sections 10.2, 10.4(c), 10.7(b) or 10.12 of the Merger Agreement adverse to the Administrative Agent, the Collateral Agent, the Lead Arranger, any Additional Agent or any Lender shall be deemed to be adverse in a material respect to the interest of the Lenders and the Lead Arranger).

Exhibit D-1

3. Refinancing of Existing Debt. Concurrently with the consummation of the Acquisition, the Refinancing shall have been consummated, all commitments relating thereto shall have been terminated, and all liens or security interests related thereto shall have been terminated or released. After giving effect to the Transactions, the Company shall have outstanding no indebtedness or preferred stock (or direct or indirect guarantee or other credit support in respect thereof) other than (i) the indebtedness in respect of the Debt Financing (or the Notes in lieu of the Bridge Loan Facility), (ii) the Acquiror’s existing 2.75% Convertible Notes due 2015 and 1.50% Convertible Notes due 2019 in the outstanding principal amounts of $345.0 million and $690.0 million, respectively, and (iii) such other limited indebtedness as may be agreed to by us and the Additional Agents.

4. Financial Information. We shall have received (A) audited consolidated balance sheets and related statements of income, stockholders’ equity and cash flows of each of the Acquired Business and the Acquiror for the last three full fiscal years ended at least 90 days prior to the Closing Date, (B) unaudited consolidated balance sheets and related statements of income, stockholders’ equity and cash flows of each of the Acquired Business and the Acquiror for each subsequent interim quarterly period ended at least 45 days prior to the Closing Date (and the corresponding period for the prior fiscal year) or, if the most recently completed fiscal period is the end of a fiscal year, ended at least 90 days before the Closing Date, (C) a pro forma consolidated balance sheet and related pro forma consolidated statement of income and statement of cash flows of the Borrower (after giving effect to the Acquisition and the other Transactions) as of and for the twelve-month period ending on the last day of the most recently completed four-fiscal quarter period ended at least 45 days prior to the Closing Date (or, if the most recently completed fiscal period is the end of a fiscal year, ended at least 90 days before the Closing Date), prepared after giving effect to the Acquisition and other Transactions as if the Transactions had occurred as of such date (in the case of such balance sheet) or at the beginning of such period (in the case of the statement of income); and (D) projections (including the assumptions on which such projections are based) for the Company for fiscal years 2014 through and including 2020.

5. Performance of Obligations. All costs, fees, expenses (including legal fees and expenses) and other compensation and amounts contemplated by the Debt Financing Letters shall have been paid to the extent due, provided that invoices therefor have been presented to the Borrower at least two business days prior to the Closing Date. You shall have complied in all material respects with all of your other covenants, agreements and obligations under Section 4 of the General Fee Letter, and the Debt Financing Letters shall be in full force and effect.

6. Customary Closing Documents. The Credit Parties (including the Acquired Business) shall have delivered (1) customary legal opinions from counsel (including New York and the Acquiror’s regulatory counsel) in form, scope and substance reasonably acceptable to the Lead Arranger and the Additional Agents, (2) a customary solvency certificate, in form and substance reasonably satisfactory to the Lead Arranger and the Additional Agents, from the chief financial officer of the Acquiror, (3) customary insurance certificates naming the Collateral Agent (on behalf of the Lenders) as an additional insured or loss payee, as the case may be, under all insurance policies to be maintained with respect to the properties of the Borrower and its subsidiaries (including the Acquired Business) forming part of the Collateral, (4) customary notices of borrowing and (5) other customary and reasonably satisfactory closing and corporate documents, resolutions, officer’s certificates, good standing certificates and UCC, judgment and tax lien searches. Without limiting the foregoing, you shall have delivered at least five business days prior to the Closing Date, all documentation and other information required by regulatory authorities under applicable “know-your-customer” and anti-money laundering rules and regulations, including the Patriot Act (to the extent requested prior to the Closing Date).

Exhibit D-2

7. Prior Marketing of Permanent Instruments and the Senior Credit Facilities. (a) With respect to the Bridge Loan Facility, we shall be satisfied that the Acquiror has used its commercially reasonable efforts to cause the Notes to be issued and sold prior to the Closing Date, which efforts shall include (a) delivery to us as soon as practicable and in no event later than 15 consecutive business days prior to the Closing Date (ending on the business day no later than the business day immediately prior to the Closing Date) a complete printed preliminary offering memorandum (the “Preliminary Offering Memorandum”) in customary form for a Rule 144A offering and usable in a customary high-yield road show relating to the issuance of the Notes that contains or incorporates by reference all financial statements and other data to be included therein (including all audited financial statements, all unaudited financial statements and all appropriate pro forma financial statements prepared in accordance with, or reconciled to, generally accepted accounting principles in the United States and prepared in accordance with Regulation S-X under the Securities Act, which shall not be required to include financial statements required by Rule 3-09, Rule 3-10 or Rule 3-16 of Regulation S-X or information required by Item 402 of Regulation S-K, but shall include customary summary information relating to guarantors and non-guarantors) and (b) the participation of senior management and representatives of the Acquiror in the road show to the extent reasonably requested. We shall have been offered a period of not less than 15 consecutive business days after delivery of such complete printed Preliminary Offering Memorandum to seek to place the Notes (ending on the business day no later than the business day immediately prior to the Closing Date) (provided, that if such 15 consecutive business day period has not ended on or prior to December 17, 2013, then it will not commence until January 6, 2014) (such period, the “Required Notes Marketing Period”).

(b) Notwithstanding the foregoing, the Required Notes Marketing Period shall be deemed not to have commenced, if prior to the completion of such 15 consecutive business day period, (A) either the Acquiror’s or the Acquired Business’ auditor shall have withdrawn its audit opinion with respect to any year end audited financial statements set forth or incorporated by reference in the Preliminary Offering Memorandum, (B) the financial statements included in the Preliminary Offering Memorandum would be required to be updated under Rule 3-12 of Regulation S-X in order to be sufficiently current on any day during such 15 consecutive business day period to permit a registration statement using such financial statements to be declared effective by the SEC on the last day of such 15 consecutive business day period, in which case the Required Notes Marketing Period shall not be deemed to commence until the receipt of updated financial information that would be required under Rule 3-12 of Regulation S-X to permit a registration statement using such financial statements to be declared effective by the SEC on the last day of such new 15 consecutive business day period, and (C) either the Acquiror or the Acquired Business shall have publicly announced any intention to restate any material financial information included in the Preliminary Offering Memorandum or that any such restatement is under consideration, in which case the Required Notes Marketing Period shall be deemed not to commence unless and until such restatement has been completed or the Company has determined that no restatement shall be required.

(c) With respect to the Senior Credit Facilities, the Lead Arranger shall have had a period of not less than 15 consecutive business days after completion of a customary Confidential Information Memorandum with respect to the Senior Credit Facilities to market and syndicate the Senior Credit Facilities (such period the “Required Bank Marketing Period”); provided, however, that if such 15 consecutive business day period has not ended on or prior to December 17, 2013, then it will not commence until January 6, 2014.

8. Comfort Letter; Negative Assurance. With respect to the Bridge Loan Facility, (A) the independent accountants that have audited the financial statements contained or incorporated by reference in the Preliminary Offering Memorandum shall make available and have delivered to us, (i) no later than the delivery to us of the Preliminary Offering Memorandum in accordance with preceding paragraph 7(a),

Exhibit D-3

in a form they are prepared to execute, a draft, reasonably acceptable to us (including, without limitation, the items included in the “circle-up” and the degree of comfort provided with respect thereto), of comfort letters prepared in accordance with the requirements of SAS 72 covering the financial statements and other data included or incorporated by reference in the Preliminary Offering Memorandum (the “Comfort Letters”), (ii) no later than the pricing of the Notes Offering, an executed copy of the Comfort Letters, and (iii) on the date of consummation of the issuance of the Notes Offering, customary “bring down” comfort letters reasonably satisfactory to us, and (B) you shall have delivered to us a customary “10b-5” legal opinion or disclosure letter from counsel to the Acquiror in form and substance reasonably satisfactory to us.

9. Notes Offering/Bridge Loans. With respect to the Senior Credit Facilities, the Acquiror shall have received not less than $750.0 million in gross cash proceeds from either (a) the issuance of the Notes in a public offering or in a Rule 144A or other private placement or (b) the borrowings under the Bridge Loan Facility.

10. Senior Credit Facilities. With respect to the Bridge Loan Facility, the Acquiror shall have received not less than $1,200.0 million in gross cash proceeds from the incurrence of the Senior Term Loans and the Revolving Credit Facility shall be in full force and effect.

11. Closing Date. The Closing Date shall occur on a business day on or after January 2, 2014.

Exhibit D-4