AVANIR Presents Positive Phase II/III Data for Neurodex at ALS/MND Conference

Study Achieved Statistical Significance in All Primary and Secondary Efficacy Parameters

SAN DIEGO, Nov. 19 /PRNewswire-FirstCall/ -- AVANIR Pharmaceuticals (Amex: AVN), a biopharmaceutical drug discovery and development company with a commercialized, FDA-approved product on the market, reported results of a Phase II/III clinical trial using Neurodex for the treatment of pseudobulbar affect (PBA) in patients with Lou Gehrig's disease (amyotrophic lateral sclerosis or ALS) during a presentation at the 13th Annual Symposium of ALS/MND. Dr. Richard A. Smith, founder of the Center for Neurologic Study and the drug's inventor, presented the data at the conference in Melbourne, Australia. PBA is a symptom of neurodegenerative diseases that manifests itself in abrupt, inappropriate or excessive displays of tearfulness or laughter.

"We are very encouraged by the favorable outcome of this pivotal trial. All of the efficacy parameters were achieved and Neurodex's side affects were as anticipated, based on the pharmacology of the active ingredient, dextromethorphan," said President and Chief Executive Officer Gerald J. Yakatan, Ph.D. "I congratulate our clinical development team and all the investigators, and commend their dedication to this first ever multicenter study of pseudobulbar affect. It is very difficult to get statistically significant results in any clinical trial where you must compare a combination drug to each of its components," continued Dr. Yakatan. "To successfully do so in a first time trial suggests that the trial design was well-planned and well-executed."

The double-blind, controlled multi-center study examined the safety and efficacy of Neurodex, an orally administered combination of dextromethorphan (DM) and quinidine sulfate (Q). Patients with Lou Gehrig's disease, who also have PBA were enrolled at 17 academic study sites throughout the U.S. A total of 140 patients were randomized to receive Neurodex capsules twice daily for four weeks or receive DM alone, or Q alone. Patients in the one-month study were assessed at screening and on the first, fifteenth and 29th day of the study.

The Neurodex arm showed statistically and clinically greater improvements than the DM only arm or the Q only arm in the primary efficacy endpoint. The primary efficacy variable for the study was change from baseline in a patient's score on the CNS-Lability Scale (CNS-LS), which is a validated scale that measures the severity and frequency of a subject's episodes of pathological laughing and/or crying. In the intent-to-treat population, adjusted mean improvement in CNS-LS for Neurodex was 1.8-fold greater than for DM (p=0.0013) and 2.0-fold greater than for Q (p=0.0002).

The laughing/crying episode rate, one of the key secondary endpoints, was significantly lower for patients treated with Neurodex than for DM or Q alone. The other secondary endpoints were the improvements in quality of life and quality of relationships. Adjusted mean improvement in overall quality of life scores for Neurodex-treated patients was 2.2-fold and 2.0-fold greater than for patients treated with DM (p=0.0015) or Q (p=0.0013) alone. Adjusted mean improvement in quality of relationship scores for Neurodex patients was 3.4-fold and 2.6-fold greater than for DM (p

Four serious adverse events (including one death attributed to the progression of ALS) were reported during the study. All four serious adverse events were considered to be unrelated to the study drug by the physician investigator who reported them. Early withdrawal due to adverse events occurred in 24% of Neurodex patients, 6% of DM patients, and 8% of Q patients. Expected Neurodex adverse events reported included nausea, dizziness, somnolence, and diarrhea. All of these adverse events resolved when therapy was discontinued.

"The positive data from this clinical trial regarding the efficacy of Neurodex provides us with the scientific rationale to proceed with clinical development in other disease states and conditions," said James E. Berg, AVANIR's Vice President of Clinical and Regulatory Affairs. "Accordingly, we have initiated a second Phase III clinical trial of Neurodex, this time in multiple sclerosis (MS) patients suffering from PBA. To broaden the scope of Neurodex's potential utility in different diseases, we are currently conducting an open label, dose-ranging Phase II study examining Neurodex in the treatment of neuropathic pain."

PBA is a symptom experienced by an estimated one million patients with various neurological conditions including ALS, Alzheimer's disease, MS, stroke and traumatic brain injury. According to a market opportunity assessment conducted by a leading provider of information solutions to the pharmaceutical and healthcare industries, the market for PBA is expected to be over $450 million in 2005 and could reach $700 million by the year 2010. Neurodex is the first drug candidate in clinical development specifically intended to treat PBA, and there are no drugs approved for PBA currently on the market. If favorable results are achieved in 2003 from the second Phase III trial of Neurodex, the Company intends to file a new drug application for review by the U.S. Food and Drug Administration (FDA) in 2004.

AVANIR Pharmaceuticals, based in San Diego, is engaged in research, discovery and development of innovative drug products for chronic diseases and, through its subsidiary Xenerex Biosciences, antibody generation services. Further information about AVANIR and Xenerex can be found at www.avanir.com and www.xenerex.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 AVANIR 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 and the Company can make no assurances that the Neurodex clinical trials will yield positive results. 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.

For further information, please contact Kristen McNally, General Information, +1-310-407-6548, kmcnally@webershandwick.com, or Tricia Ross, Analyst/Investor, +1-310-407-6540, tross@webershandwick.com, or Tim Grace, Media, +1-312-640-6667, tgrace@webershandwick.com, all of FRB|Weber Shandwick, for AVANIR Pharmaceuticals; or Patrice Saxon, Investor Relations of AVANIR Pharmaceuticals, +1-858-622-5202, psaxon@avanir.com.

SOURCE AVANIR Pharmaceuticals

/CONTACT: Kristen McNally, General Information, +1-310-407-6548, kmcnally@webershandwick.com, or Tricia Ross, Analyst/Investor, +1-310-407-6540, tross@webershandwick.com, or Tim Grace, Media, +1-312-640-6667, tgrace@webershandwick.com, all of FRB|Weber Shandwick, for AVANIR Pharmaceuticals; or Patrice Saxon, Investor Relations of AVANIR Pharmaceuticals, +1-858-622-5202, psaxon@avanir.com/

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