PharmAthene Completes Pharmacokinetic Studies of Protexia; Program on Target for IND Filing in 2008

ANNAPOLIS, Md., March 6, 2008 /PRNewswire-FirstCall/ -- PharmAthene, Inc., a biodefense company specializing in the development and commercialization of medical countermeasures against chemical and biological threats, announced today that it has completed the initial pharmacokinetic (PK) testing of Protexia(R), the Company's broad spectrum chemical nerve agent prophylaxis.

The PK studies were conducted in two animal species and used the final pegylated version of rBChE for the first time. In general, the conjugation of proteins with polyethylene glycol (PEG) has been shown to decrease immunogenicity, increase circulating serum half-life and increase stability of recombinant proteins. The data from these studies confirm that the specific PEG chosen for conjugation to rBChE will significantly improve the half-life of the protein in vivo.

The PK studies demonstrated that Protexia(R) had a half life of approximately four days in primates and three days in rodents when administered by intramuscular injection. These data compare favorably with what was predicted for the drug's PK profile in these animal species.

John Troyer, Ph.D., Senior Program Director for Protexia(R), commented, "These results are very meaningful in that they show that Protexia(R) meets or exceeds our target product profile for use as a chemical nerve agent prophylaxis. The impressive half life data also confirm that the pegylation of rBChE as part of our manufacturing process achieved the goal of extending the half-life of the protein to one which makes it a feasible product for use in humans."

Dr. Troyer continued, "Having successfully completed the PK studies, we are on target to complete our toxicology studies and file the Investigational New Drug (IND) application for Protexia(R) in the third quarter of 2008; we expect to commence Phase I human safety testing of Protexia(R) in the fourth quarter."

"Today's announcement highlights the intense commitment and strong technical capability PharmAthene has continually demonstrated in our attempts to rapidly progress our biodefense product portfolio. Since acquiring Protexia(R), we have defined a viable manufacturing process for commercial scale production and demonstrated proof of concept showing protection with Protexia(R) against highly lethal doses of nerve agent exposure," said David P. Wright, President and Chief Executive Officer.

"Our proven internal expertise in drug development, in combination with the funding and partnership provided under our DoD contract, will significantly enhance our ability to ensure that Protexia(R) becomes an important part of the nation's military and civilian biodefense arsenal," continued Mr. Wright.

In September 2006, PharmAthene was awarded a multi-year contract from the Department of Defense (DoD) U.S. Army Space and Missile Command valued at up to $213 million assuming all extensions and options are exercised by the DoD, for advanced development of the Company's broad spectrum chemical nerve agent prophylaxis, Protexia(R). The contract includes a procurement option by the DoD for an initial 90,000 doses of Protexia(R). The Protexia(R) contract was awarded through a full and open competitive solicitation seeking novel second generation prophylactic products for use in humans to prevent and treat poisoning from organophosphorus (OP) nerve agents such as sarin gas, soman, tabun and VX.

About Protexia(R): PEGylated Recombinant Human Butyrylcholinesterase (rBChE)

Protexia(R) is a form of recombinant human butyrylcholinesterase (rBChE), a potent organophosphorus (OP) scavenger protein produced in the milk of transgenic goats, which is being developed for use as a prophylactic against acute organophosphorus (OP) nerve agent toxicity.

About Chemical Weapons

Organophosphorus nerve agents, or anti-cholinesterase agents, were discovered in the 1930s following intensive research into new insecticides. Their discovery represents the beginning of modern chemical warfare. These agents cause toxicity by binding to and inhibiting acetylcholinesterase, an enzyme in the body that is essential for nervous system function, leading to increases in acetylcholine and "cholinergic crisis" that can cause loss of muscle control, respiratory failure, paralysis, convulsions, permanent brain damage and eventually death.

These so-called nerve gases, which are actually all liquids at room temperature, are lethal far more quickly and in far lower concentrations than other classical chemical warfare agents such as vesicants, choking agents and blood agents, and are effective both when inhaled and when absorbed through the skin. Nerve agents can be classified as either G-agents (sarin, soman, tabun) or V-agents (VX), both of which are exceedingly toxic.

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 programs include Valortim(TM) for the prevention and treatment of anthrax infection and Protexia(R) for the prevention and treatment of morbidity and mortality associated with exposure to chemical nerve agents. For more information on PharmAthene, please visit www.PharmAthene.com.

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"; "could"; or similar statements are forward-looking statements. PharmAthene disclaims, however, any intent or obligation to update these forward-looking statements. 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 Protexia(R), unexpected funding delays, unforeseen safety issues, unexpected determination that Protexia(R) proves not to be effective or capable of being marketed as a product, as well as risks detailed from time to time in PharmAthene's public disclosure filings with the U.S. Securities and Exchange Commission (the "SEC"). There can be no assurance that such development efforts will succeed or that other developed products will receive required regulatory clearance, or that, even if such regulatory clearance were received, such products would ultimately achieve commercial success. Copies of PharmAthene's public disclosure filings are available from its investor relations department.

CONTACT: Stacey Jurchison, Director, Corporate Communications ofPharmAthene, Inc., +1-410-269-2610, Cell: +1-410-474-8200, JurchisonS@PharmAthene.com

Web site: http://www.pharmathene.com//

Ticker Symbol: (AMEX:PIP)

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Posted: March 2008

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