COMMON STOCK PURCHASE AGREEMENT

This COMMON STOCK PURCHASE AGREEMENT (this “Agreement”) is made and entered into as of February 11, 2009 (the “Effective Date”).

DOR BioPharma Inc., a Delaware corporation having its principal office at 850 Bear Tavern Road, Suite 201, Ewing, New Jersey 08628 (hereinafter referred to as the “Company”),

SIGMA-TAU Pharmaceuticals, Inc, a Nevada corporation having its principal office at 9841 Washingtonian Blvd., Suite 500, Gaithersburg, MD 20878 (hereinafter referred to as the “Purchaser”).

WHEREAS , the Company has developed and is developing through its research activities Beclomethasone Dipropionate (orBec ^® ) and owns and/or controls the related know-how and patents; and

WHEREAS , the Company and the Purchaser are entering into a Collaboration and Supply   Agreement (the “Supply Agreement”) concerning Beclomethasone Dipropionate (orBec ^® ) dated as of the date hereof; and

WHEREAS , shares of the Company’s common stock, par value $.001 per share (“Common Stock”), are listed on the Over -The- Counter bulletin board securities market (the “Market”), symbol “DORB”; and

WHEREAS , in connection with the activities under the Supply Agreement, the Company desires to sell and issue to the Purchaser, and the Purchaser, in order to support  further development of Beclomethasone Dipropionate (orBec ^® ), wishes to purchase from the Company, twenty-five million (25,000,000) shares of Common Stock (“Shares”).

NOW, THEREFORE , for good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged by the parties, the parties agree as follows:

1.   Definitions .  The following terms as used in this Agreement (or the Schedule(s) hereto) have the meanings set forth below:

1.1.   “Affiliates” means, with respect to a party, (i) any entity, more than fifty percent (50%) of the voting equity interests of which is owned and/or controlled directly or indirectly by such party; (ii) any entity which directly or indirectly owns and/or controls more than fifty percent (50%) of the voting equity interests of such party; (iii) any entity which is directly or indirectly under common control of the referenced party through common ownership or which is directly or indirectly under common control of the respective shareholders of such party.

1.2.   “Agreement” has the meaning set forth in the introductory paragraph.

1.3.   “Closing” has the meaning set forth in Article 3.1.

1.4.   “Closing Date” has the meaning set forth in Article 3.1.

1.5.   “Common Stock” has the meaning set forth in the recitals.

1.6.   “Company” has the meaning set forth in the introductory paragraph.

1.7.   “Company’s Knowledge” means the actual knowledge of the executive officers and directors of the Company, after due and reasonable inquiry.

1.8.   “Effective Date” has the meaning set forth in the introductory paragraph.

1.9.   “Exchange Act” has the meaning set forth in Article 5.3.

1.10.   “Holder” has the meaning set forth in Article 7.

1.11.   “Market” has the meaning set forth in the recitals.

1.12.   “Marketing Authorizations” has the meaning set forth in Article 8.2.

1.13.   “Permits” has the meaning set forth in Article 5.11.

1.14.   “Phase 3 Trial” has the meaning set forth in the Supply Agreement.

1.15.   “Piggyback Registration” has the meaning set forth in Article 7.2.

1.16.   “Preferred Stock” has the meaning set forth in Article 5.6(a).

1.17.   “Proceeds” has the meaning set forth in Article 2.1.

1.18.   “Product” has the meaning set forth in the Supply Agreement.

1.19.   “Proprietary Rights” has the meaning set forth in Article 5.10.

1.20.   “Purchaser” has the meaning set forth in the introductory paragraph.

1.21.   “Registrable Securities” shall mean (i) the Shares, (ii) the shares of Common Stock purchased from the Company by the Purchaser on November 26, 2008 and (iii) any common stock issued as a dividend or other distribution with respect to, or in exchange for or in replacement of, such above-described securities; provided , however , that “Registrable Securities” shall not include any securities sold by a person either pursuant to a registration statement or Rule 144 as promulgated by the SEC under the Securities Act, as such Rule may be amended from time to time, or any similar successor rule that may be promulgated by the SEC.

1.22.   “SEC” has the meaning set forth in Article 5.8.

1.23.   “SEC Reports” has the meaning set forth in Article 5.14.

1.24.   “Securities Act” has the meaning set forth in Article 5.3.

1.25.   “Shares” has the meaning set forth in the recitals.

1.26.   “Sigma-Tau Nominee” has the meaning set forth in Article 8.1.

1.27.   “Supply Agreement” has the meaning set forth in the recitals.

2.   Purchase and Sale of Shares .

2.1.   At the Closing, subject to the terms and conditions contained in this Agreement, in payment of the full purchase price for the Shares, the Purchaser shall provide a wire transfer of immediately available funds to the Company in an amount equal to Four and One-Half Million Dollars (US $4,500,000) (the “Proceeds”) using the following wire transfer instructions:

Bank Name:                                UBS AG

ABA No.:                                026007993

A/C  Name:                                UBS Financial Services

Beneficiary:                                DOR BIOPHARMA, INC.

Account No.:                                Y300354

3.   Closing; Deliveries at Closing .

3.1.   Closing .  The purchase and sale of the Shares shall take place at a closing (the “Closing”) to be held at the offices of Edwards Angell Palmer & Dodge LLP, 750 Lexington Avenue, New York, New York 10022, at 10:00 a.m. Eastern Time on the date of this Agreement, or at such other location, time and date as may be mutually agreed upon by the parties (the “Closing Date”).  The Closing shall take place contemporaneously with the execution and delivery of this Agreement by the parties thereto.

3.2.   Deliveries at Closing .   Within thirty (30) days from the Closing, the Company shall deliver a stock certificate evidencing the Shares, all issued in the name of the Purchaser and dated as of the Closing Date.

4.   Conditions to Closing .

4.1.   Conditions to the Purchaser’s Obligations at Closing .  The obligation of the Purchaser to purchase and pay for the Shares at the Closing is subject to each of the following conditions precedent:

(a)   Officer’s Certificate .  The Purchaser shall have received at the Closing, a certificate, executed by the appropriate officer of the Company and dated as of the Closing Date, together with and certifying (i) the names of the officers of the Company authorized to sign this Agreement together with the true signatures of such officers; (ii) a copy of the Certificate of Incorporation of the Company, as amended and in effect as of the Closing Date; (iii) a copy of the Bylaws of the Company, as amended and in effect as of the Closing Date; (iv) that the representations and warranties contained in Article 5 hereof are true and correct as of the Closing Date; and (v) the Company has complied with all the agreements and satisfied all the conditions herein on its part to be performed or satisfied on or prior to the Closing Date;

(b)   Instruction Letter .  The Company shall have transmitted an instruction letter to its stock transfer agent directing it to issue to the Purchaser the stock certificate for the Shares, and the Purchaser shall have received a copy of such letter.

(c)   Conditions to Company’s Obligations at Closing .  The obligation of the Company to issue and sell the Shares at the Closing is subject to the delivery by the Purchaser of the Proceeds in immediately available funds to Company’s specified account in accordance with Article 2.1.

5.   Representations and Warranties by the Company . The Company represents and warrants to the Purchaser as follows:

5.1.   Organization and Standing .  The Company is a corporation duly organized, validly existing and in good standing under the laws of the State of Delaware and has the requisite corporate power and authority to own, lease and operate its properties and to carry on its business as now being conducted.  The Company is qualified to do business and is in good standing as a foreign corporation in every jurisdiction in which the failure to so qualify would have a material adverse effect on the financial condition or business of the Company.

5.2.   No Actions .  There are no legal or governmental actions, suits, proceedings or investigations pending or, to the Company’s knowledge, threatened to which the Company is or may be a party or of which property owned or leased by the Company is or may be the subject, or related to environmental or discrimination matters, which actions, suits, proceedings or investigations, individually or in the aggregate, might prevent or might reasonably be expected to have a material adverse affect on the transactions contemplated by this Agreement or the financial condition or business of the Company.  The Company is not a party to, or subject to the provisions of, any material injunction, judgment, decree or order of any court, regulatory body, administrative agency or other governmental body.

5.3.   Compliance with Other Instruments .  The execution and delivery of, and the performance and compliance with this Agreement and the transactions contemplated hereby, with or without the giving of notice, will not (i) result in any breach of, or constitute a default under, or result in the imposition of any lien or encumbrance upon any asset or property of the Company pursuant to any agreement or other instrument to which the Company is a party or by which it or any of its properties, assets or rights is bound or affected, (ii) violate the Certificate of Incorporation or Bylaws of the Company, or, subject to the accuracy of the representations and warranties of the Purchaser contained in Article 6 of this Agreement, any law, rule, regulation, judgment, order or decree or (iii) except for the registration of the Shares under the Securities Act of 1933, as amended (the “Securities Act”), and such consents, notifications, approvals, authorizations, registrations or qualifications as may be required under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and applicable state securities or “blue sky” laws in connection with the purchase of the Shares by the Purchaser, the issuance of the Shares and the listing of the Shares on the Market do not require any consent, notification, approval, authorization or order of or filing with any court or governmental agency or body.  The Company is not in violation of its Certificate of Incorporation, as amended, or Bylaws, as amended, nor in violation of, or in default under, any lien, mortgage, lease, agreement or instrument, except for such defaults which would not, individually or in the aggregate, have a material adverse effect on the financial condition or business of the Company.  The Company is not subject to any restriction which would prohibit the Company from entering into or performing its obligations under this Agreement.

5.4.   Shares .  The Shares when issued and paid for pursuant to the terms of this Agreement, will be duly and validly authorized, issued and outstanding, fully paid, nonassessable and free and clear of all pledges, liens, encumbrances and restrictions (other than arising under federal or state securities or “blue sky” laws).  The issuance of the Shares is not subject to any preemptive or other similar rights.

5.5.   Securities Laws .  Subject to the accuracy of the representations and warranties of the Purchaser contained in Article 6 of this Agreement, the offer, sale and issuance of the Shares as contemplated by this Agreement are exempt from the registration requirements of the Securities Act, and from the registration or qualifications requirements of the laws of any applicable state or other U.S. jurisdiction.

5.6.   Authorized Capital Stock .

(a)   The capital stock of the Company, as authorized by the Company’s Certificate of Incorporation immediately prior to the Closing, consists of 250,000,000 shares of Common Stock, 4,600,000 shares of preferred stock, par value $.001 per share, 200,000 shares of Series B preferred stock, par value $.05 per share,  and 200,000 shares of Series C preferred stock, par value $.05 per share  (collectively, “Preferred Stock”).  Immediately prior to the Closing, 139,524,739 shares of Common Stock and no shares of the Preferred Stock are issued and outstanding.  All of the outstanding shares of the Company’s capital stock are duly authorized, validly issued, fully paid and nonassessable and were issued in compliance with all applicable federal and state securities laws and have been issued and sold in compliance with all applicable preemptive or similar rights of all persons.

(b)   Except as set forth on Schedule 5.6(b) , there are no outstanding subscriptions, options, warrants, rights, calls, contracts, demands, commitments, conversion rights or other agreements or arrangements of any character or nature whatever under which the Company is or may be obligated (i) to issue or sell shares of its Common Stock or Preferred Stock, or (ii) to register shares of its Common Stock or Preferred Stock.  No holder of any security of the Company is entitled to any preemptive or similar rights to purchase any securities of the Company.

5.7.   Corporate Acts and Proceedings .  This Agreement has been duly authorized by the requisite corporate action and has been duly executed and delivered by an authorized officer of the Company, and is a valid and binding obligation of the Company, enforceable in accordance with its terms, except as such enforceability may be limited by bankruptcy, insolvency, moratorium, reorganization or other similar laws affecting the enforcement of creditors’ rights generally and as to limitations on the enforcement of the remedy of specific performance and other equitable remedies.  The requisite corporate action necessary to the authorization, reservation, issuance and delivery of the Shares has been taken by the Company.

5.8.   Filing of Reports .  Since the Company’s Annual Report on Form 10-KSB for the fiscal year ended December 31, 2007, the Company has filed with the Securities and Exchange Commission (the “SEC”) all reports and other material required to be filed by it therewith.

5.9.   Compliance with Laws . The business and operations of the Company have been conducted in accordance with all applicable laws, rules and regulations of all governmental authorities, except for such violations which would not, individually or in the aggregate, have a material adverse effect on the financial condition or business of the Company.

5.10.   Proprietary Rights .  No executive officer or director of the Company has any actual knowledge, after due and reasonable inquiry, of, nor has the Company given or received any notice of, any pending conflicts with or infringement of the rights of others with respect to any patents, patent applications, inventions, trademarks, trade names, applications for registration of trademarks, service marks, service mark applications, copyrights, know-how, manufacturing processes, formulae, trade secrets, licenses and rights in any thereof and any other intangible property and assets (herein called the “Proprietary Rights”) which are material to the business of the Company, as now conducted or as proposed to be conducted.  No action, suit, arbitration, or legal, administrative or other proceeding, or investigation is pending or, to the Company’s Knowledge, threatened which involves any Proprietary Rights.  The Company is not subject to any judgment, order, writ, injunction or decree of any court or any federal, state, local, foreign or other governmental department, commission, board, bureau, agency or instrumentality, domestic or foreign, or any arbitrator, and the Company has not entered into or is a party to any contract which restricts or impairs the use of any such Proprietary Rights in a manner which would have a material adverse effect on the financial condition or business of the Company.  The Company has not received written notice of any pending conflict with or infringement upon any third-party proprietary rights by the Company.

5.11.   Permits and Licenses .  The Company owns, possesses or has obtained, and is operating in compliance with, all governmental, administrative and third party licenses, permits, certificates, registrations, approvals, consents and other authorizations (collectively, “Permits”) necessary to own or lease (as the case may be) and operate its properties, whether tangible or intangible, and to conduct its businesses or operations as currently conducted, except such licenses, permits, certificates, registrations, approvals, consents and authorizations the failure of which to obtain would not have a material adverse effect on the business, properties, operations, financial condition or results of operations of the Company, and the Company has not received any notice of proceedings relating to the revocation, modification or suspension of any Permits and, to the Company’s Knowledge, there exists no circumstance which would lead it to believe that such proceedings are reasonably likely.

5.12.   Insurance .    The Company maintains insurance of the type and in the amount reasonably adequate for its business, including, but not limited to, insurance covering all real and personal property owned or leased by the Company against theft, damage, destruction, acts of vandalism and all other risks customarily insured against by similarly situated companies, all of which insurance is in full force and effect.

5.13.   Changes .  Since the Company filed its Form 10-Q on November 14, 2008, the Company has not, to the extent material to the Company, (i) incurred any debts obligations or liabilities, absolute, accrued or contingent, whether due or to become due, other than in the ordinary course of busi