PharmAthene (PIP) Announces Full Exercise of Over-Allotment Option

ANNAPOLIS, Md., Nov. 24, 2010 /PRNewswire-FirstCall/ — PharmAthene, Inc., (NYSE Amex: PIP) a biodefense company developing medical countermeasures against biological and chemical threats, today announced that the 645,000 share over-allotment option granted to the underwriter in conjunction with the registered public offering consummated on November 3, 2010 was exercised in full on November 22, 2010.  The closing of the sale of the related shares occurred on November 23, 2010.

The sale of the over-allotment shares generated net proceeds, before expenses, of approximately $2.1 million, which the Company intends to use for repayment of debt and general corporate purposes.

Roth Capital Partners, LLC served as sole underwriter for the offering. Noble Financial Capital Markets served as the Company’s financial advisor in connection with the offering.

The securities described above were offered by PharmAthene pursuant to a registration statement previously filed and declared effective by the Securities and Exchange Commission on February 13, 2009. This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction. The securities may be offered only by means of a prospectus, including a prospectus supplement, forming a part of the effective registration statement. Copies of the prospectus and the final prospectus supplement may be obtained, when available, at the Securities and Exchange Commission’s website at http://www.sec.gov/. Copies of the prospectus and the final prospectus supplement may also be obtained from Roth Capital Partners, LLC Equity Capital Markets, 24 Corporate Plaza, Newport Beach, CA 92660, at 800-678-9147 and Rothecm@roth.com.

About PharmAthene, Inc.

PharmAthene was formed to meet the critical needs of the United States and its allies by developing and commercializing medical countermeasures against biological and chemical weapons. PharmAthene’s lead product development programs include:

• SparVax™ – a second generation recombinant protective antigen (rPA) anthrax vaccine
• Valortim® – a fully human monoclonal antibody for the prevention and treatment of anthrax infection
• Countermeasures for nerve agent poisoning by organophosphate compounds, including nerve gases and pesticides, whose active ingredient is the recombinant enzyme, butyrylcholinesterase (rBChE)

Statement on Cautionary Factors

Except for the historical information presented herein, matters discussed may constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 that are subject to certain risks and uncertainties that could cause actual results to differ materially from any future results, performance or achievements expressed or implied by such statements. Statements that are not historical facts, including statements preceded by, followed by, or that include the words “potential”; “believe”; “anticipate”; “intend”; “plan”; “expect”; “estimate”; “could”; “may”; “should”; “will”; “project”; “potential”; or similar statements are forward-looking statements. PharmAthene disclaims any intent or obligation to update these forward-looking statements other than as required by law. Risks and uncertainties include risk associated with the reliability of the results of the studies relating to human safety and possible adverse effects resulting from the administration of the Company’s product candidates, unexpected funding delays and/or reductions or elimination of U.S. government funding for one or more of the Company’s development programs, the award of government contracts to our competitors, unforeseen safety issues, challenges related to the development, scale-up, technology transfer, and/or process validation of manufacturing processes for our product candidates, unexpected determinations that these product candidates prove not to be effective and/or capable of being marketed as products, challenges related to the implementation of our NYSE Amex compliance plan, (for example, if the Exchange deems PharmAthene’s progress toward compliance inadequate or if PharmAthene does not satisfy the NYSE Amex continuing listing standards by January 26, 2010), as well as risks detailed from time to time in PharmAthene’s Forms 10-K and 10-Q under the caption “Risk Factors” and in its other reports filed with the U.S. Securities and Exchange Commission (the “SEC”).

Copies of PharmAthene’s public disclosure filings are available from its investor relations department and our website under the investor relations tab at www.PharmAthene.com.