AVANIR's Anthrax Antibody Data Presented at 2005 ASM Biodefense Research Meeting

SAN DIEGO--(BUSINESS WIRE)--March 22, 2005--AVANIR Pharmaceuticals' (AMEX:AVN) anti-anthrax monoclonal antibodies have demonstrated an ability to protect against the most lethal form of anthrax toxins in animal models. Data from additional studies conducted by Johnny W. Peterson, Ph.D., of the University of Texas Medical Branch were presented today in a poster entitled "Human Monoclonal Antibodies to Protective Antigen with and without Ciprofloxacin Protect Mice and Guinea Pigs against Inhalation Anthrax" at the 2005 American Society for Microbiology (ASM) Biodefense Research Meeting being held this week in Baltimore, Maryland.

"Human anti-PA monoclonal antibodies supplied by AVANIR Pharmaceuticals have been shown to protect against lethal infection in mice and guinea pigs challenged with B. anthracis spores instilled into the respiratory tract," said Dr. Peterson. "Our research indicates delay in death and survival is significantly increased by co-administration of antibodies with low levels of ciprofloxacin."

The in vivo tests on passive immunization with AVANIR human monoclonal antibodies are being conducted in small animal models established at the University of Texas Medical Branch in Galveston under contract from the National Institute of Allergy and Infectious Disease (NIAID), a division of the National Institutes of Health. "AVANIR's human monoclonal antibodies to protective antigen (PA), such as AVP-21D9, have high specificity and very desirable binding properties, and offer considerable promise for the rapid development of products useful as adjuncts to current antimicrobial prophylaxis and therapy against inhalation anthrax," continued Dr. Peterson.

Antibodies that neutralize anthrax toxins may augment existing treatment options. Currently, a vaccine and antibiotics are the treatment options available for the prevention or treatment of anthrax exposure. Both approaches have limitations. The anthrax vaccine takes weeks following the first doses before immunity is established, and requires multiple injections over a period of months, in addition to annual boosters, to reach and maintain its protective effect. Antibiotics, the standard treatment of anthrax infection, are effective in killing anthrax bacteria, but have no effect on the anthrax toxins.

"These data indicate that AVP-21D9 may provide the necessary immediate protection before other treatment regimens take effect," concluded Dr. Peterson.

AVANIR Pharmaceuticals is a drug discovery and development company focused on treatments for chronic diseases. Our product candidates address therapeutic markets that include central nervous system and cardiovascular disorders, inflammation, and infectious disease. The Company's first commercialized product, Abreva(R), is marketed in North America by GlaxoSmithKline Consumer Healthcare and is the leading over-the-counter product for the treatment of cold sores. Further information about AVANIR can be found at www.avanir.com.

Except for the historical information presented herein, matters discussed in this press release contain forward-looking statements 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 that are preceded by, followed by, or that include such words as "estimate," "anticipate," "believe," "plan" or "expect" or similar statements are forward-looking statements. Risks and uncertainties for AVANIR Pharmaceuticals include risks associated with product discovery and development, our dependence on government grants to subsidize the development of our anthrax antibodies, as well as risks shown in AVANIR's most recent Annual Report on Form 10-K and Quarterly Report on Form 10-Q and from time-to-time in other publicly available information regarding the company. Copies of such information are available from AVANIR upon request. Such publicly available information sets forth many risks and uncertainties related to AVANIR's business and technology. Avanir's monoclonal antibody technology competes with several technologies used by large pharmaceutical and biotechnology companies and is subject to a number of uncertainties, including risks associated with the success of clinical trials, the progress of research and product development programs, the regulatory approval process, competitive products, future capital requirements and commercialization risks, particularly with drug candidates being developed for the U.S. federal government. There can be no assurance that such development efforts will succeed, that such products will receive required regulatory clearance, or that even if such regulatory clearance were received, that such products would ultimately achieve commercial success. The company disclaims any intent or obligations to update these forward-looking statements.

    CONTACT: AVANIR Pharmaceuticals
             Patrice Saxon, 858-622-5202 (Investor Relations)

    SOURCE: AVANIR Pharmaceuticals