Zenvia is a drug that is a combination of the therapeutically active ingredient dextromethorphan and quinidine, the enzyme inhibitor for increasing the bioavailability of dextromethorphan. Zenvia is used for treating Involuntary Emotional Expression Disorder (IEED) and DPN pain.

Though the company received an approvable letter for using Zenvia to treat IEED in October 2006, the company has initiated a confirmatory Phase III study to cater for new lower quinidine dose formulation of Zenvia. AVANIR had managed to complete the first part of their studies in diabetic peripheral neuropathic pain in April 2007. This study found that all primary endpoints successfully met. AVANIR is now considering another study for a lower dose of quinidine in the second PHASE III trial for DPN plan.

The company then held studies where two doses of Zenvia, were compared to placebo that was based on the dietary entries of the Pain Rating Scale. This was referred to as the primary endpoint as defined in Special Protocol Assessment with U.S. Food and Drug Administration. In this study, it was found that the people in the Zenvia treatment group had lower pain ratings than the placebo patients.

This study was also effective in proving improvements in key secondary endpoints like the Pain Relief Ratings Scale and Pain Intensity Ratings Scale. Moreover, safety data from this study proved to be consistent with data provided from previous studies. The only side effects reported from these studies were diarrhea, fatigue, nausea, dizziness and somnolence which were mild to moderate in nature.