AVANIR Antibodies Demonstrate Potent Efficacy Against Anthrax Spore Challenge in Animals; Data Presented at BIOPHEX Meeting

SAN DIEGO--(BUSINESS WIRE)--Sept. 24, 2003--AVANIR Pharmaceuticals (AMEX: AVN) said its Xenerex(TM) technology has generated multiple antibodies that demonstrate high potency against anthrax toxins in vitro and in vivo and against anthrax spores in vivo. Mice protected by a single dose of one of AVANIR's lead antibodies, AVP-8C1, against a lethal challenge of anthrax spores, were still completely protected on subsequent exposure to anthrax spores four weeks later. The immediate immunity conferred by the antibody appears to assist in the establishment of long-lasting immunity.

Phillip R. Morrow, Ph.D., co-inventor of AVANIR's Xenerex technology and featured speaker at the BIOPHEX Conference, presented data today in San Jose, Calif., on six antibodies generated by AVANIR's antibody research group against the protective antigen (PA) anthrax toxin. Developed by Genetic Engineering News, the BIOPHEX Conference features tracks on monoclonal antibodies, vaccines and proteomics.

AVANIR Pharmaceuticals is developing the antibodies for use as a prophylactic and therapeutic drug to prevent and treat anthrax infections. Grants from the U.S. Department of Defense administered through CCAT -- the Center for Commercialization of Advanced Technology -- have already been awarded to facilitate the company's early antibody development efforts. AVANIR plans to work with federal authorities and the federal grant programs available to fund the remaining FDA-required testing of biodefense products.

AVANIR is also in discussions with potential partner companies capable of antibody production in an effort to file an Investigational New Drug application seeking to begin clinical trials. Under the Bioterrorism Act of 2002, the FDA specified that human clinical trials for biodefense products will be required to establish safety, tolerability and pharmacology, resulting in an abbreviated clinical trials process.

About Xenerex(TM) Technology

AVANIR'S Xenerex(TM) technology is used to develop human monoclonal antibodies for the treatment of infectious diseases and other therapeutic applications. The patented technology provides a powerful platform for accessing human monoclonal antibodies against disease antigens. The technology involves engrafting human immune cells into mice that lack a functional immune system. Immunizing the mice with disease agents result in the production of human antibodies against the disease targets. The cells making the antibodies are recovered from the mice and immortalized to produce fully human monoclonal antibodies against the disease targets.

About the Company

AVANIR Pharmaceuticals is a drug discovery and development company focused on the development of treatments for central nervous system disorders and inflammatory diseases. The company's first commercialized FDA-approved product, Abreva(R), is marketed in North America by GlaxoSmithKline and is the leading over-the-counter product for the treatment of cold sores. The company's lead product candidate, Neurodex(TM), is in Phase III clinical development for pseudobulbar affect and in Phase II clinical development for neuropathic pain. An internally developed small molecule, AVP 13358, is in a Phase I clinical trial for the treatment of allergy and asthma. Using its proprietary Xenerex(TM) technology, AVANIR also develops human monoclonal antibodies for infectious diseases and other therapeutic applications. 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, 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: Redington Inc.
Thomas Redington, 203-222-7399
AVANIR Pharmaceuticals
Patrice Saxon, 858-622-5202

SOURCE: AVANIR Pharmaceuticals