AVANIR Presents Data on Novel Mechanism of Action at the American Academy of Allergy, Asthma and Immunology National Meeting.

SAN DIEGO -- AVANIR Pharmaceuticals (AMEX:AVN) today announced that data on AVP-13358 was presented at the 2005 national meeting of the American Academy of Allergy, Asthma and Immunology (AAAAI). The poster "A Small Molecule Compound (AVP-13358) in Phase I Clinical Development Suppresses Experimental Allergy in Animals Via a Distinctly Novel Mechanism" describes a unique activity profile for AVP-13358.

Previous data have shown that AVP-13358 exhibits a profile that inhibits the generation of important mediators associated with development of allergy and asthma. These mediators include IgE antibodies, the cytokine IL-4, and the IgE receptor CD23. AVANIR has now identified a common pathway to account for the unique profile of AVP-13358. The pathway involves regulation of certain proteins located in a sub-cellular organelle known as the Golgi. AVANIR believes suppression of these proteins with AVP-13358 inhibits the secretion of IgE and IL-4 and the expression of CD23, and thus may "quiet" the hyperactive cells typically found in the airways of allergy and asthma sufferers. These data support a decidedly novel mechanism of action, and provide a theoretical basis of action for the AVANIR compounds.

"Other than the inhibitors of leukotrienes, there have been no new drugs with novel mechanisms of actions approved for the treatment of asthma in the last 30 years," said Jagadish Sircar, Vice President of Drug Development for AVANIR. "Asthma is a multi-factorial disorder and a drug that inhibits multiple mediators may offer advantages over more specific agents. Corticosteroids suggest this is a valid approach, however, the use of steroids is limited by their toxicity. Theoretically, AVANIR's compounds may not have similar limitations because they target hyper-responsive cells while leaving constitutive cellular processes relatively unperturbed."

The abstract accepted for presentation at the AAAAI meeting was published in the February 2005 supplement to the Journal of Allergy and Clinical Immunology.

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.

The information contained in this press release, including any forward-looking statements contained herein, should be reviewed in conjunction with the Company's most recent Annual Report on Form 10-K and other publicly available information regarding the Company. Copies of such information are available from the company upon request. Such publicly available information sets forth many risks and uncertainties related to the Company's business and technology. Forward-looking statements often contain such words like "estimate," "anticipate," "believe," "plan" or "expect." Our IgE modulation program competes with other research approaches and compounds under development by large pharmaceutical and biotechnology companies. Preclinical research findings are not always supportable by evidence obtained from subsequent clinical trials. Final review decisions made by the FDA and other regulatory agencies concerning clinical trial results are unpredictable and outside the influence and/or control of the Company. AVANIR disclaims any intent or obligation to update these forward-looking statements.