Shares of Avanir Pharmaceuticals, Inc. (Nasdaq: AVNR) were up more than 15 percent in after-hours trading on Friday after it was reported on TheStreet.com that the U.S. Food and Drug Administration approved Avanir’s Nuedexta for the treatment of pseudobulbar affect.

Pseudobulbar affect (PBA), sometimes called emotional incontinence refers to a neurologic disorder characterized by involuntary crying or uncontrollable episodes of crying and/or laughing, or other emotional displays. Prevalence estimates place the number of people with PBA between 1.5 million and 2 million in the United States alone. However, given the fact that PBA is a relatively common disorder among patients with various neurologic conditions, its actual prevalence may be higher.
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Carol Werther of SummerStreet Research Partners, an independent healthcare research firm, predicted the approval in an Oct. 15 note to clients.

“We expect a label to treat the signs and symptoms of PBA with warnings not to use with drugs that increase QTc wave prolongation,” the note stated. “Data from the advanced cardiac safety study (ACSS) indicates that AVP-923, even using a 10mg dose of quinidine, still prolongs the QTc (mean of 8.9 ms), just above the level the FDA considers no risk for Torsades de Pointes. (5 msec). Nevertheless, we do not think this will stop approval as many marketed drugs have similar profiles. AVNR submitted a risk map program to prevent abuse of AVP-923.”

Nuedexta, formerly known as AVP-923 and the trade name Zenvia™, 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. Avanir is developing Nuedexta for use in PBA and diabetic peripheral neuropathic pain.

“The FDA approval of NUEDEXTA marks an important milestone for people living with PBA, an under-recognized and debilitating neurologic condition,” said Keith Katkin, president and chief executive officer of Avanir in a statement. “The approval of NUEDEXTA also marks AVANIR’s transition toward becoming a commercial enterprise, ready to support the successful launch of the first FDA-approved treatment for PBA. We expect that NUEDEXTA will be available by prescription during the first quarter of 2011.”

Shares of Avanir Pharmaceuticals are down about 13 percent in the past three months.