AVANIR Reports Positive Interim Phase I Safety Data on Asthma/Allergy Drug Candidate; Potential Asthma/Allergy Product Modulates IgE and Th2 Cytokines Orally

SAN DIEGO--(BUSINESS WIRE)--Oct. 21, 2003--AVANIR Pharmaceuticals (AMEX: AVN) said interim results show its experimental asthma/allergy drug, AVP 13358, was well-tolerated at single rising doses in a randomized, placebo-controlled Phase I clinical trial for safety and bioavailability. Presence of the drug in the bloodstream, or exposure, was demonstrated at all four oral dose levels from 1 to 5 mg.

"We are pleased that AVP 13358 was well tolerated at each of these initial doses," noted Laura Pope, Ph.D., AVANIR'S senior director of clinical and regulatory affairs. "It also is significant that exposure to the drug was demonstrated at each of the tested doses. We are clearly encouraged by these results and look forward to continuing the trial with higher dose levels."

AVANIR is developing AVP 13358 as a potential treatment for allergy and asthma by targeting IgE and other known mediators of allergy and asthma. AVANIR's orally active compound acts early in the body's response to allergens by inhibiting the production or release of mediators involved in allergy and asthma. The approach is considered unique because it selectively down regulates not only the production of IgE released by the immune system in response to allergen exposure, but also a critical group of cytokines -- called Th2 -- thought to regulate the physiological processes that ultimately manifest as allergies or asthma.

"The recently approved injectable antibody Xolair(R) has been reported to target only IgE, and doesn't inhibit its synthesis or release," said Gerald J. Yakatan, Ph.D., president and CEO of AVANIR Pharmaceuticals. "There are no orally active drugs currently marketed for the treatment of excess IgE and Th2 cytokines. AVANIR believes that a compound that acts on these critical mediators could provide a valuable new therapy for the treatment of allergy and asthma."

In allergic asthma, IgE production is triggered when the substance one is allergic to, the allergen, enters the blood stream. The IgE binds with the allergen and forms a complex that causes inflammatory cells to release chemicals that fight off the invading agents. The chemicals released by these cells are what causes the wheezing and other symptoms seen in asthma. These can also trigger symptoms such as sneezing and hives. The majority of currently available therapeutics counteract the symptoms of the disease but are considered palliative because they do not treat the underlying cause of disease, IgE and Th2 cytokines.

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 (IL-4Ra) 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 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.

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. 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: At Redington Inc.
Thomas Redington, 203-222-7399
tredington@redingtoninc.com
or
AVANIR Pharmaceuticals
Investor Relations:
Patrice Saxon, 858-622-5202
psaxon@avanir.com

SOURCE: AVANIR Pharmaceuticals