AVANIR Reports Encouraging Results from Phase I Study of Asthma/Allergy Drug Candidate

SAN DIEGO--(BUSINESS WIRE)--May 3, 2004--AVANIR Pharmaceuticals (AMEX:AVN) today announced the completion of the initial Phase I clinical trial for its experimental asthma/allergy drug, AVP 13358. The study included 54 healthy volunteers and was intended to assess safety, tolerability and pharmacokinetics following a single oral administration. Results from the study suggest AVP 13358 was well tolerated at all doses. The study also demonstrated AVP 13358 was detectable in the bloodstream at all doses administered and remains in circulation long enough to allow once or twice daily dosing.

"We are very pleased to see the level of exposure, tolerability and the promising pharmacokinetic profile that our compound has exhibited in this clinical trial," said Jagadish Sircar, Ph.D., Vice President of Drug Discovery at AVANIR Pharmaceuticals.

AVANIR is developing AVP 13358 as a potential treatment for allergy and asthma by targeting IgE and other known mediators of allergy and asthma. Immunoglobulin epsilon or IgE, is released by the immune system in response to allergen exposure. AVANIR's approach is considered unique because it selectively down-regulates the production of allergen specific IgE as well as another critical group of mediators called Th2 cytokines that are up-regulated during asthma or allergic episodes.

About AVP 13358

AVP 13358 is a novel drug molecule discovered by scientists at AVANIR that is intended to inhibit the production of IgE, a well-known mediator of allergy and asthma. In addition to its effect on IgE, this compound has demonstrated an ability to suppress the antigen-stimulated IL-4 and IL-5 responses with potencies similar to those observed for IgE suppression. AVP 13358 also suppresses markers of disease in mouse models of asthma, including pulmonary lavage levels of IL-4, IL-5, eosinophils, and lymphocytes, as well as expression of CD23 and the IL-4 receptor (IL4R(alpha)) on leukocytes. No inhibitory effects on antigen-specific IgG responses were observed. AVP 13358 is orally active and appears to be selective for the suppression of antigen specific IgE and Th2 cytokine-mediated diseases.

About the Company

AVANIR Pharmaceuticals is a drug discovery and development company focused on the development of treatments for chronic diseases. The Company's lead product candidate, Neurodex(TM), is in Phase III clinical development for the treatment of pseudobulbar affect. Neurodex(TM) is also in Phase II clinical development for the treatment of neuropathic pain. The Company's first commercialized product, Abreva(R), is marketed in North America by GlaxoSmithKline 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." The Company disclaims any intent or obligation to update these forward-looking statements. AVP 13358 is at a very early stage of clinical development. 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. Final review decisions made by the FDA and other regulatory agencies concerning clinical trial results of AVP 13358 and the Company's other development programs are unpredictable and outside the influence and/or control of the company. The company disclaims any intent or obligations to update these forward-looking statements.

CONTACT: AVANIR Pharmaceuticals
Patrice Saxon (Investor Relations), 858-622-5202
psaxon@avanir.com

SOURCE: AVANIR Pharmaceuticals