AVANIR's Anthrax Antibody Profiled in the Journal of Immune Based Therapeutics and Vaccine

Independent U.S. Army Medical Research on AVANIR's Antibody Also Reported at American Society for Microbiology Meeting

SAN DIEGO--(BUSINESS WIRE)--June 4, 2004-- AVANIR Pharmaceuticals' (AMEX:AVN) anti-anthrax monoclonal antibodies protected rats from lethal anthrax toxins, according to a study published in the peer-reviewed Journal of Immune Based Therapies and Vaccine, released today: (http://www.jibtherapies.com/content/pdf/1476-8518-2-5.pdf). AVANIR is developing the human monoclonal antibodies to prevent and treat anthrax infections.

Additionally, the results of independent research conducted at the United States Army Medical Research Institute of Infectious Diseases (USAMRIID) on one of AVANIR's anti-anthrax antibodies was presented by Dr. Susan Welkos at the 104th General Meeting of the American Society for Microbiology, in New Orleans, La. The research was conducted by Dr. Welkos, Dr. Christopher K. Cote and Dr. Cynthia Rossi, of the Bacteriology and Diagnostic Systems Division at USAMRIID, and funded by the Medical Chemical Biodefense Research Program, U.S. Army Medical Research and Materiel Command. Dr. Welkos reported that AVANIR's antibody demonstrated in-vitro activity against anthrax spores.

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 may take several weeks following the first doses before immunity is established, and requires multiple injections over a period of 18 months, in addition to annual boosters, to maintain its presumed protective effect. Antibiotics, the standard treatment of anthrax infection, are effective in killing anthrax bacteria, but have no effect on the anthrax toxins.

AVANIR Pharmaceuticals, based in San Diego, is a drug discovery and development company focused primarily on novel treatments for chronic diseases. The Company's most advanced product candidate, Neurodex(TM), is in Phase III clinical development for the treatment of pseudobulbar affect, also known as emotional lability. Neurodex(TM) is also in Phase II clinical development for the treatment of neuropathic pain. A potential treatment for allergy and asthma, AVP-13358, is in Phase I clinical development. AVANIR also develops human monoclonal antibodies for infectious diseases and other therapeutic applications. 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. The Xenerex(TM) 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 and future capital requirements. 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, Investor Relations, 858-622-5202

SOURCE: AVANIR Pharmaceuticals