Avanir Pharmaceuticals has received priority review status for Neurodex from the US Food and Drug Administration (FDA). Neurodex is indicated for the treatment of involuntary emotional expression disorder (IEED), also known as pseudobulbar affect or emotional lability, the company said in a press release.

The FDA grants priority review status to products that, if approved, would address an unmet medical need or are considered to be potentially significant therapeutic advancements over existing approved therapies in the treatment, diagnosis or prevention of a disease. Avanir completed the submission of its NDA to the FDA on January 27, 2006 and expects the FDA will take action on the NDA by July 30, 2006 (the "PDUFA date").

Neurodex, a combination of dextromethorphan and low dose quinidine, is safe and effective in reducing the frequency and severity of unpredictable and uncontrollable episodes of IEED that occur as a consequence of neurological disease or injury.

Two controlled, multicenter Phase III clinical trials were conducted; one in amyotrophic lateral sclerosis (ALS) patients with IEED, and the other in multiple sclerosis (MS) patients with IEED. In the clinical studies Neurodex achieved a statistically significant reduction in the Center for Neurologic Study Lability Scale (CNS-LS), a validated instrument that assesses frequency and severity of IEED episodes which was the primary efficacy endpoint in both studies.

Additionally, Neurodex achieved statistical significance in all secondary endpoints, including reduction in episodes of IEED. In these clinical trials, the most common adverse events (AEs) associated with Neurodex were nausea, dizziness, fatigue, diarrhea and headache. The majority of AEs reported were mild or moderate, most occurring in the first week of treatment. More patients on Neurodex discontinued due to adverse events than patients in control groups.

Involuntary emotional expression disorder can occur when disease or injury damages the area of the brain that controls normal expression of emotion. This damage can disrupt brain signaling, causing a "short circuit", triggering episodes of involuntary emotional expressions. IEED episodes are often sudden, unpredictable, and contrary to the patient's mood.

Patients who experience unpredictable involuntary emotional displays are often anxious and embarrassed by them, and avoid social situations, which can result in isolation. It is hypothesized that neurological diseases and traumatic brain injuries may lead to excessive signaling via glutamate, an excitatory neurotransmitter, which can manifest itself as IEED. Currently, there is no approved product indicated for the treatment of IEED which occurs in patients with neurological disorders including ALS, MS, Parkinson's disease, dementias including Alzheimer's disease, and brain injuries such as stroke and traumatic brain injury.

Neurodex is a combination of two well-characterized compounds, the active ingredient dextromethorphan, and the enzyme inhibitor quinidine, which serves to increase the bioavailability of dextromethorphan. The first-in-class drug candidate is believed to help regulate excitatory neurotransmission in two ways, through presynaptic inhibition of glutamate release via sigma-1 receptor agonist activity, and through postsynaptic glutamate response modulation via uncompetitive, low-affinity NMDA antagonist activity.

Avanir had previously announced positive results in the second of two required Phase III clinical trials of Neurodex, an investigational new drug for the treatment of involuntary emotional expression disorder (IEED). Additionally, Avanir has initiated a phase III clinical trial for Neurodex as a potential treatment in patients with diabetic neuropathic pain, a second indication for Neurodex.