REGISTRATION RIGHTS AGREEMENT

Exhibit 10.5

REGISTRATION RIGHTS AGREEMENT

by and among

CORNERSTONE THERAPEUTICS INC.
and
CHIESI FARMACEUTICI SPA,

Dated as of May 6, 2009

TABLE OF CONTENTS

REGISTRATION RIGHTS AGREEMENT

     This REGISTRATION RIGHTS AGREEMENT , dated as of May 6, 2009 (this “ Agreement ”), is by and among CORNERSTONE THERAPEUTICS INC., a Delaware corporation, (the “ Company ”), and CHIESI FARMACEUTICI SPA, a corporation organized under the laws of Italy (“ Purchaser ”).

RECITALS

      WHEREAS , concurrently with the execution and delivery of this Agreement, (i) Purchaser and certain stockholders of the Company are entering into a Stock Purchase Agreement (the “ Initial Stock Purchase Agreement ”), dated the same date as this Agreement, and (ii) the Company and Purchaser are entering into a Stock Purchase Agreement (the “ Company Stock Purchase Agreement ”), also dated the same date as this Agreement;

      WHEREAS , following consummation of the transactions contemplated by the Initial Stock Purchase Agreement and the Company Stock Purchase Agreement, Purchaser will own approximately 13,502,741 shares of the Company’s common stock, par value $0.001 per share (the “ Common Stock ”); and

      WHEREAS , the parties wish to provide for certain registration rights that are to take effect upon the closings of the transactions provided for in the Initial Stock Purchase Agreement and the Company Stock Purchase Agreement;

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

ARTICLE I

DEFINITIONS

     Section 1.1 Certain Definitions . As used in this Agreement, the following terms shall have the following respective meanings:

     “ Affiliate ” means, with respect to any Person, any other Person that directly, or indirectly through one or more intermediaries, controls, is controlled by or is under common control with the Person specified.

     “ Beneficially Own ” means, with respect to any security, having or sharing the power to direct or control the voting or disposition of such security and “ Beneficial Ownership ” has a correlative meaning.

     “ Board ” or “ Board of Directors ” means the Board of Directors of the Company except where the context otherwise requires.

     “ Business Day ” means any day other than a Saturday, Sunday or day when commercial banks in New York City are permitted or required by law to be closed for the conduct of regular banking business.

     “ Common Stock ” means the Company’s common stock, par value $0.001 per share.

     “ Demand Registration ” means any registration of Registrable Securities under the Securities Act requested by Purchaser in accordance with Section 2.1 .

     “ Effective Date ” means the date of the Closing provided for in the Company Stock Purchase Agreement.

     “ Exchange Act ” means the Securities Exchange Act of 1934, as amended, and the rules and regulations of the SEC promulgated thereunder.

     “ Excluded Registration ” means a registration under the Securities Act of (i) securities on Form S-8 or any similar successor form or (ii) securities to effect the acquisition of, or combination with, another Person registered on Form S-4 or any similar successor form.

     “ FINRA ” means the Financial Industry Regulatory Authority.

     “ FINRA Rules ” means the rules of the Financial Regulatory Authority, Inc., including the NASD Rules as incorporated into the FINRA Transitional Rule Book, as amended, and any successor rules.

     “ Governance Agreement ” means the Governance Agreement, dated the same date as this Agreement, by and among the Company, Purchaser and, solely with respect to the sections identified therein, certain stockholders of the Company named therein.

     “ hereto ”, “ hereunder ”, “ herein ”, “ hereof ” and words of similar import, when used in this Agreement, refer to this Agreement as a whole and not to any particular provision of this Agreement.

     “ Material Disclosure Event ” means, as of any date of determination, any pending or imminent event relating to the Company or any of its subsidiaries that the Board reasonably determines in good faith, after consultation with outside counsel to the Company, (i) would require disclosure of material, non-public information relating to such event in any registration statement or related prospectus including Registrable Securities (including documents incorporated by reference therein) so that such registration statement would not be materially misleading, (ii) would not otherwise be required to be publicly disclosed by the Company at that time in a periodic report to be filed with or furnished to the SEC under the Exchange Act but for the filing of such registration statement or related prospectus and (iii) if publicly disclosed at the time of such event, could reasonably be expected to have a material adverse effect on the business, financial condition, prospects or results of operations of the Company and its subsidiaries or would materially adversely affect a pending or proposed material acquisition, merger, recapitalization, consolidation, reorganization, financing or similar transaction, or negotiations with respect thereto.

     “ Person ” means any natural Person, corporation, general partnership, limited partnership, limited or unlimited liability company, proprietorship, joint venture, other business organization, trust, union, association or any U.S. or non-U.S. government, regulatory or administrative authority, agency, instrumentality or commission or any court, tribunal, judicial or arbitral body or other similar authority.

     “ Piggyback Registration ” means any registration of Registrable Securities under the Securities Act requested by Purchaser in accordance with Section 2.2 .

     “ Registrable Securities ” means shares of Common Stock that are Beneficially Owned by Purchaser and any securities into which such shares may have been converted pursuant to any merger, corporate reorganization or other similar transaction, unless (i) such securities have been effectively registered under Section 5 of the Securities Act and disposed of pursuant to an effective registration statement, or (ii) such securities may be transferred pursuant to Rule 144 under the Securities Act without volume limitations such that, after any such transfer referred to in this clause (ii), such securities thereafter may be freely transferred without restriction under the Securities Act.

     “ Rule 144 ” means Rule 144 promulgated by the Commission under the Securities Act, and any successor provision thereto.

     “ SEC ” means the Securities and Exchange Commission.

     “ Securities Act ” means the Securities Act of 1933, as amended, and the rules and regulations of the SEC promulgated thereunder.

     “ Shelf Registration ” means a registration of the Company Common Stock in a continuous or delayed offering pursuant to Rule 415 under the Securities Act (or any successor rule).

     “ Underwritten Offering ” means a firm commitment underwritten public offering pursuant to an effective registration statement under the Securities Act, other than pursuant to a registration statement on Forms S-4 or S-8 or any similar or successor form.

     Section 1.2 Interpretation .

     (a) When a reference is made in this Agreement to an Article or a Section hereof, such reference shall be to an Article or a Section of this Agreement unless otherwise indicated.

     (b) The table of contents and headings contained in this Agreement are for reference purposes only and shall not affect in any way the meaning or interpretation of this Agreement.

     (c) The parties have participated jointly in negotiating and drafting this Agreement. If an ambiguity or a question of intent or interpretation arises, this Agreement shall be construed as if drafted jointly by the parties, and no presumption or burden of proof shall arise favoring or disfavoring any party by virtue of the authorship of any provisions of this Agreement.

     (d) The definitions contained in this Agreement are applicable to the singular as well as the plural forms of such terms.

     (e) References to a Person are also to its permitted successors and assigns.

     (f) The use of “or” is not intended to be exclusive unless expressly indicated otherwise.

ARTICLE II

REGISTRATION RIGHTS

     Section 2.1 Demand Registrations .

     (a) If at any time after the Blackout Period (as defined in the Governance Agreement), the Company shall receive a notice from Purchaser that the Company effect a Demand Registration (a “ Demand Notice ”), for all or any portion of the Registrable Securities specified in such Demand Notice, specifying the intended method of disposition thereof, then the Company shall use its reasonable best efforts to effect within 60 days of such Demand Notice, subject to the restrictions of this Section 2.1 , the registration under the Securities Act of the Registrable Securities for which Purchaser has requested registration under this Section 2.1 , all to the extent necessary to permit the disposition (in accordance with the intended methods thereof as specified in the Demand Notice) of the Registrable Securities so to be registered.

     (b) Subject to the provisions of this Section 2.1 , Purchaser shall be entitled to request four (4) Demand Registrations.

     (c) Subject to Section 2.1(e) , the Company shall file the registration statement in respect of a Demand Registration as soon as practicable and, in any event, within 45 days after receiving a Demand Notice (the “ Required Filing Date ”) on Form S-1 or S-3 or any similar or successor to such forms under the Securities Act, or, if they are not available, any form for which the Company then qualifies, and which form shall be available for the sale of the Registrable Securities in accordance with the intended methods of distribution thereof, and shall use its reasonable best efforts to cause the same to be declared effective by the SEC as promptly as practicable after such filing; provided , that the Company shall not be obligated to effect a Demand Registration pursuant to Section 2.1(a) (i) within 180 days after the effective date of a previous Demand Registration and (ii) unless the Demand Notice is for a number of Registrable Securities with an expected market value that is equal to at least $50,000,000 as of the date of such Demand Notice or is for one hundred percent of Registrable Securities.

     (d) With respect to any Demand Registration, subject to the availability of a registration statement on Form S-3, the Company shall, upon written request from Purchaser, agree to effect a Shelf Registration, and, thereafter, shall use its reasonable best efforts to cause such registration statement to be declared effective under the Securities Act as promptly as practicable after the filing thereof.

     (e) The Company may defer the filing (but not the preparation) of a registration statement required by this Section 2.1 until after the Required Filing Date (i) for a period not to exceed 90 days, if, at the time the Company receives the Demand Notice, there exists a Material Disclosure Event, or (ii) for a period not to exceed 90 days, if, prior to receiving the Demand Notice, the Company had determined to effect a registered underwritten public offering of Company Common Stock, or securities convertible into or exchangeable for Company Common Stock, for the Company’s account in connection with a material public financing transaction and the Company had taken substantial steps (including selecting a managing underwriter for such offering, if applicable) and is proceeding with reasonable diligence to effect such offering. A deferral of the filing of a registration statement pursuant to this Section 2.1(e) shall be lifted, and the requested registration statement shall be filed forthwith, if, in the case of a deferral pursuant to clause (i) of the preceding sentence, the Material Disclosure Event is publicly disclosed or otherwise ceases to exist, or, in the case of a deferral pursuant to clause (ii) of the preceding sentence, the proposed registration for the Company’s account is abandoned or the filing of a registration statement with respect to any such proposed registration is delayed by more than 30 days from the time of receipt of the applicable Demand Notice. In order to defer the filing of a registration statement pursuant to this Section 2.1(e) , the Company shall promptly (but in any event within 10 days), upon determining to seek such deferral, deliver to Purchaser a certificate signed by an executive officer of the Company stating that the Company is deferring such filing pursuant to this Section 2.1(e) , a general statement of the reason for such deferral and an approximation of the anticipated delay. Within 20 days after receiving such certificate, Purchaser may withdraw such Demand Notice by giving notice to the Company; if withdrawn, the Demand Notice shall be deemed not to have been made for all purposes of this Agreement and the Company shall pay all expenses of such withdrawn Demand Registration in accordance with Section 2.7 . The Company may defer the filing of a particular registration statement pursuant to this Section 2.1(e) only once in any period of 12 consecutive months; provided , that any deferral pursuant to clause (i) of the first sentence of this Section 2.1(e) shall be deemed to be a “Suspension Period” for purposes of Section 2.6 and shall be subject to the limitations and obligations during Suspension Periods set forth in Section 2.6 .

     (f) No securities to be sold for the account of any Person (including the Company), other than Purchaser shall be included in a Demand Registration if the managing underwriters (or, in an offering that is not underwritten, a nationally recognized investment bank) shall advise the Company and

Purchaser in writing that the aggregate amount of such securities requested to be included in any offering pursuant to such Demand Registration is sufficiently large to have an adverse effect on the success of any such offering, based on market conditions or otherwise (an “ Adverse Effect ”). Furthermore, if the managing underwriters (or such investment bank) shall advise the Company and Purchaser that, even after exclusion of all securities of other Persons pursuant to the immediately preceding sentence, the amount of Registrable Securities proposed to be included in such Demand Registration by Purchaser is sufficiently large to cause an Adverse Effect, the Registrable Securities of Purchaser to be included in such Demand Registration shall equal the number of shares which Purchaser is so advised can be sold in such offering without an Adverse Effect; provided , that the Company shall not include any Registrable Securities of any executive officer, director or employee of the Company or any of its subsidiaries if the managing underwriters (or such investment bank) shall advise the Company and Purchaser that the participation of any such persons may have an Adverse Effect; provided , further that if the number of Registrable Securities to be included in the Demand Registration is less than 80% of the number requested to be so included, Purchaser may withdraw such Demand Notice by giving notice to the Company; if withdrawn, the Demand Notice shall be deemed not to have been made for all purposes of this Agreement and the Company shall pay all expenses of such withdrawn Demand Registration in accordance with Section 2.7 ; provided , however, that if the holders of a majority of the remaining Registrable Securities covered by such Demand Notice desire to proceed with such Demand Registration, the Company shall proceed forward with such Demand Registration and the Demand Notice shall be deemed to have been made for all purposes of this Agreement by the remaining holders.

     (g) Purchaser may withdraw Registrable Securities from a Demand Registration at any time and Purchaser shall have the right to cancel a proposed Demand Registration of Registrable Securities pursuant to this Section 2.1(g) . Upon such cancellation, the Company shall cease all efforts to secure registration and such Demand Registration shall not be counted as a Demand Registration under this Agreement for any purpose and the Company shall pay the expenses of such cancelled Demand Registration in accordance with Section 2.7 .

     (h) In any registration requested pursuant to this Section 2.1 , the Company shall not register securities other than Registrable Securities for sale for the account of any Person (including the Company), unless permitted to do so by the written consent of Purchaser.

     Section 2.2 Piggyback Registrations .

     (a) Whenever the Company proposes to register any of its equity securities under the Securities Act (other than a registration statement on Form S-8 or on Form S-4 or any similar successor forms), whether for its own account or for the account of one or more stockholders of the Company, the Company shall each such time give prompt written notice at least 20 business days prior to the anticipated filing date of the registration statement relating to such registration to Purchaser, which notice shall set forth Purchaser’s rights under this Section 2.2 and shall offer Purchaser the opportunity to include in such registration the number of Registrable Securities of the same class or series as those proposed to be registered as Purchaser may request, subject to the provisions of Sections 2.2(a) , 2.2(b) and 2.2(c) . Upon the request of Purchaser made within 15 business days after the receipt of notice from the Company (which request shall specify the number of Registrable Securities, if any, intended to be registered by Purchaser), the Company shall use its reasonable best efforts to effect the registration under the Securities Act of all Registrable Securities that the Company has been so requested to register by Purchaser to the extent necessary to permit the disposition of the Registrable Securities so to be registered; provided , that (i) if such registration involves an Underwritten Offering, Purchaser must sell all Registrable Securities to the underwriters selected by the Company on the same terms and conditions as apply to the Company, as applicable, and (ii) if, at any time after giving notice of its intention to register any securities pursuant to this Section 2.2(a) and prior to the effective date of the registration statement filed in connection with

such registration, the Company shall determine for any reason not to register such securities, the Company shall give notice to Purchaser and, thereupon, shall be relieved of its obligation to register any Registrable Securities in connection with such registration. No registration effected under this Section 2.2 shall relieve the Company of its obligations to effect a Demand Registration to the extent required by Section 2.1 . There shall be no limitation on the number of Piggyback Registrations that the Company shall be required to effect under this Section 2.2 .

     (b) At any time prior to the effective date of the registration statement relating to such registration, Purchaser may revoke such Piggyback Registration request by providing a notice to the Company revoking such request.

     (c) If a Piggyback Registration is in respect of an Underwritten Offering and was initiated by the Company, and if the managing underwriters advise the Company that the inclusion of Registrable Securities requested to be included in the registration statement pursuant to this Section 2.2 would cause an Adverse Effect, then the Company shall be required to include in such registration statement, to the extent of the amount of securities that the managing underwriters advise may be sold without causing such Adverse Effect, (A) first , the securities the Company proposes to sell; (B) second , the Registrable Securities requested to be included in such registration by Purchaser thereof; and (C) third , any other securities requested to be included in such registration; provided , that the Company shall not include any Registrable Securities of any executive officer or employee of the Company or any of its subsidiaries (other than the Stockholders) if such managing underwriters advise the Company and the requesting Stockholders that the participation of any such individual may have an Adverse Effect. If, as a result of the provisions of this Section 2.2(c) , any Stockholder shall not be entitled to include all Registrable Securities in a registration that such Stockholder has requested to be so included, such Stockholder may withdraw such Stockholder’s request to include Registrable Securities in such registration statement.

     (d) If a Piggyback Registration is in respect of an Underwritten Offering and was initiated by a security holder of the Company (other than a Stockholder), and if the managing underwriters advise the Company that the inclusion of Registrable Securities requested to be included in the registration statement would cause an Adverse Effect, the Company shall include in such registration statement, to the extent of the amount of securities that the managing underwriters advise may be sold without causing such Adverse Effect, (A)  first , the Registrable Securities requested to be included in such registration by any Stockholder thereof, pro rata among the Stockholders on the basis of the number of Registrable Securities requested to be registered by each such Stockholder; and (B)  second , any other securities requested to be included in such registration (including securities to be sold for the account of the Company); provided , that the Company shall not include any Registrable Securities of any executive officer or employee of the Company or any of its subsidiaries (other than Purchaser) if such managing underwriters advise the Company and Purchaser that the participation of any such individual may have an Adverse Effect. If, as a result of the provisions of this Section 2.2(d) , Purchaser shall not be entitled to include all Registrable Securities in a registration that Purchaser has requested to be so included, Purchaser may withdraw its request to include Registrable Securities in such registration statement.

     (e) Notwithstanding any of the foregoing, the provisions of Sections 2.2(c) and 2.2(d) shall not apply to a Piggyback Registration that is a Shelf Registration.

     Section 2.3 SEC Forms . The Company shall use its reasonable best efforts to cause any Demand Registrations to be registered on Form S-3 (or any successor form), if applicable, once the Company becomes eligible to use Form S-3. If the Company is not then eligible under the Securities Act to use Form S-3, such Demand Registrations shall be registered on the form for which the Company then qualifies. The Company shall use its best efforts to become and remain eligible to use Form S-3. All such registration statements shall comply with applicable requirements of the Securities Act, and, together

with each prospectus included, filed or otherwise furnished by the Company in connection therewith, shall not contain any untrue statement of material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading.

     Section 2.4 Holdback Agreements .

     (a) The Company agrees (i) not to effect any public sale or distribution of its equity securities, or any securities convertible into or exchangeable or exercisable for such securities, except pursuant to Excluded Registrations, during the seven days prior to the effective date of any registration statement in connection with a Demand Registration or Piggyback Registration and thereafter until the date on which all of the Registrable Securities subject to such registration statement have been sold (not to exceed 90 days, as required by the underwriters managing the offering) and (ii) if requested by the managing underwriters, to use reasonable efforts to cause each director and executive officer to agree not to effect any public sale or distribution (including sales pursuant to Rule 144 of the Securities Act) of any such securities during such period (except as part of such underwritten registration, if otherwise permitted); provided , that the foregoing described holdback shall not apply to the extent that the managing underwriters of such offering otherwise agree or, in the event a registration statement does not relate to an Underwritten Offering, if the holders of a majority of such Registrable Securities consent thereto.

     (b) If Purchaser notifies the Company in writing that it intends to effect an underwritten sale of Company Common Stock registered pursuant to a Shelf Registration, the Company agrees (i) not to effect any public sale or distribution of its equity securities, or any securities convertible into or exchangeable or exercisable for its equity securities, during the seven days prior to and during the 90-day period beginning on the filing of the prospectus supplement with respect to such offering, other than pursuant to Excluded Registrations or to the extent that the managing underwriters of such offering otherwise agree and (ii) if requested by the managing underwriters, to use reasonable efforts to cause each director and executive officer to agree not to effect any public sale or distribution (including sales pursuant to Section 144) of any such securities during such period (except as part of such underwritten registration, if otherwise permitted).

     (c) Purchaser agrees, in the event of an Underwritten Offering by the Company (whether for the account of the Company or otherwise), not to effect any public sale or distribution of any Registrable Securities, or any securities convertible into or exchangeable or exercisable for such Registrable Securities, including any sale pursuant to Rule 144 (except as part of such Underwritten Offering), during the seven days prior to and ending up to 90 days after the date of the final prospectus, subject in each case to such extensions as are customary to permit the publication of research in compliance with Rule 2711(f) of the rules of the National Association of Securities Dealers, Inc. as incorporated in the FINRA Rules (or any similar successor rule thereto); provided , that each other stockholder of the Company and each executive officer of the Company is subject to substantially the same restrictions.

     Section 2.5 Registration Procedures . Whenever Purchaser has requested that any Registrable Securities be registered pursuant to this Agreement, the Company shall use its best efforts to effect the registration and the sale of such Registrable Securities in accordance with the intended method of disposition thereof as promptly as is practicable, and pursuant thereto the Company shall as expeditiously as possible:

     (a) prepare and file with the SEC by the Required Filing Date a registration statement on the appropriate form under the Securities Act with respect to such Registrable Securities and use its best efforts to cause such registration statement to become effective as soon as practicable after the initial filing thereof; provided , that as far in advance as practicable before filing such registration statement or

any amendment or supplement thereto, the Company shall furnish to Purchaser copies of reasonably complete drafts of all such documents prepared to be filed (including exhibits and documents that are to be incorporated by reference into the registration statement, amendment or supplement), and Purchaser shall have the opportunity to object to any information contained therein and the Company shall m