AVANIR Reports Positive Phase II Clinical Data With Neurodex for Neuropathic Pain

SAN DIEGO, Jun 12, 2003 /PRNewswire-FirstCall via COMTEX/ -- AVANIR Pharmaceuticals (Amex: AVN) announced today the results of a four week open label dose escalation study of Neurodex in patients with painful diabetic neuropathy. Results indicated that Neurodex was well tolerated up to the highest target dose, and patients reported decreased pain intensity that was significantly different from baseline (p < 0.0001). In addition, by Day 8, 91% of the patients reported pain relief compared to baseline, and 97% reported pain relief by Day 15. The degree of pain relief increased with duration of the study.

The clinical trial was conducted at six U.S. sites in 36 adult volunteers with diabetic neuropathy who experience pain on a daily basis in the lower extremities. The study was designed to evaluate the safety and tolerability of escalating doses of Neurodex for future clinical trials. Various pain assessments were included as a preliminary evaluation of pain relief. The 5-point Likert Pain Intensity Rating Scale was administered on Days 1, 8, 15, 22 and 29 where mean pain intensity was reduced from moderate-to-severe at baseline to none-to-mild at Day 29. The Pain Relief Rating Scale (a 6-point Likert scale) administered on Days 8, 15, 22, and 29 showed a statistically significant difference (from 0) at all time points. Also administered in the clinic on Days 1 and 29 was a Peripheral Neuropathy Quality of Life Scale that showed statistically significant improvement at Day 29 compared to Day 1. Additional assessments from daily patient diary records including a sleep rating scale and an activity rating scale showed similar patterns of change.

Three patients did not complete the study, two due to adverse events (one serious and not related, one serious and possibly related) and one due to inability to comply with the protocol. Commonly reported adverse events (reported by 3 or more individuals) included nausea, constipation, diarrhea, dry mouth, fatigue, dizziness, insomnia, headache, upper respiratory tract infection, and somnolence. Most adverse events were either mild or moderate in intensity, and 92% of participants completed the study. There was minimal need for rescue pain medication; rescue medications were taken on a mean of 1.3 days during the study.

Gerald J. Yakatan, Ph.D., AVANIR's President and Chief Executive Officer, said the study's results support the Company's plans to develop Neurodex as a viable competitor in the $1 billion plus neuropathic pain market.

"Results of a recently commissioned market opportunity assessment indicated physicians are far from satisfied with existing treatments for their patients suffering from chronic pain," said Dr. Yakatan. "Physicians surveyed indicated high interest in a new product specifically indicated for neuropathic pain, especially for their highly motivated pain patients."

About Diabetic Neuropathy

At least half of the 15.7 million Americans who have diabetes are estimated to suffer from nerve damage caused by the disease, according to the American Diabetes Association. The damaged nerves can alter the sensitivity of pain centers in the spinal cord and consequently intensify pain transmission within the central nervous system.

Diabetic neuropathic pain currently is most commonly treated with tricyclic antidepressants, anticonvulsants, opioid analgesics and local anesthetics. Most of these treatments have limited effectiveness and undesirable side effects. There is no drug approved in the U.S. specifically for diabetic neuropathic pain.

About Neurodex

AVANIR has the exclusive license to develop, manufacture and market Neurodex for four potential indications: pseudobulbar affect, neuropathic pain, chronic cough and weaning drug-dependent patients from narcotics and anti-depressants. The Company is conducting a second Phase III clinical trial for pseudobulbar affect, having completed one of the two pivotal clinical trials required for submission of a new drug application to the U.S. Food and Drug Administration (FDA). Neurodex for pseudobulbar affect could reach the FDA for review by 2004. Neurodex is protected by six issued U.S. patents.

Neurodex is comprised of dextromethorphan (DM) and an enzyme inhibitor that significantly slows the metabolism of DM and is administered in capsule form. Although DM is considered to be neuroprotective and could be useful in treating certain central nervous system disorders based on key receptor interactions, the therapeutic utility of DM alone is limited due to its rapid metabolism. Blocking the metabolism with the inhibitor makes it possible to maintain therapeutic levels of DM for a longer period of time with relatively small doses.

About the Company

AVANIR Pharmaceuticals, based in San Diego, is a drug discovery and development company with a commercialized FDA-approved product (Abreva(R)) and products in clinical development for the treatment of pseudobulbar affect (Phase III), neuropathic pain (Phase II), and allergy and asthma (Phase I). AVANIR is engaged in small-molecule research to develop treatments for central nervous system disorders and inflammatory diseases. Through the use of its 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 .

AVANIR press releases and presentations, including any forward-looking statements contained therein, 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 as "estimate," "anticipate," "intend," "plan" or "expect." Research findings are not always supportable by evidence obtained from subsequent clinical trials. This Phase II open label study was a non-placebo controlled trial and, therefore, will not be acceptable as one of the two clinical trials required for FDA approval. The Company can make no assurances that the Neurodex Phase III clinical trials will yield positive results. Final review decisions made by the FDA and other regulatory agencies concerning Neurodex clinical trial results are unpredictable and outside the influence and/or control of the company.

SOURCE AVANIR Pharmaceuticals

Media, Vince Heald of Beck Ellman Heald, +1-858-453-9600, vheald@behmedia.com, for AVANIR Pharmaceuticals; or Patrice Saxon, Investor Relations of AVANIR Pharmaceuticals, +1-858-622-5202, psaxon@avanir.com