ALISO VIEJO, Calif., Feb. 8, 2012 /PRNewswire/ -- Avanir Pharmaceuticals, Inc. (NASDAQ: AVNR) announced today that the results of the study entitled "Efficacy and Safety of Dextromethorphan/Quinidine (AVP-923) at Two Dosage Levels for Diabetic Neuropathic Pain: A Double-Blind, Placebo-Controlled, Multicenter Study" have been published in the February edition of the journal Pain Medicine. "Throughout a 13-week trial, AVP-923 was effective, with an acceptable safety profile, for treatment of diabetic peripheral neuropathic pain. The findings indicate that other fixed-dose combinations of AVP-923 should be studied to improve overall tolerability while maintaining significant efficacy," said Aziz Shabaini, MD, Medical Director of the Nerve and Muscle Center, Texas. AVP-923 is a combination of dextromethorphan (DM) and quinidine (Q). AVP-923 is currently being studied in a Phase II clinical trial (the PRIME study) in central neuropathic pain in patients with multiple sclerosis. "Today's publication in a leading peer-review medical journal complements a body of scientific literature suggesting that dextromethorphan could be efficacious in neuropathic pain," said Joao Siffert, MD, senior vice president of research and development at Avanir. "These results provide additional rationale in support of the ongoing PRIME study, which is evaluating the combination of dextromethorphan and quinidine in central neuropathic pain in patients with multiple sclerosis." Study Design In a 13-week, phase III, randomized, controlled trial, 379 adults with daily symmetric diabetic peripheral neuropathy (DPN) leg pain for >3 months received double-blind placebo, DMQ 45/30 mg, or DMQ 30/30 mg, administered once daily for 7 days and twice daily thereafter. Efficacy measures included four pain rating scales applied daily using patient diaries, and another two applied at five clinic visits. Safety and tolerability were assessed by adverse event reports, physical examination, electrocardiogram and clinical laboratory tests. Patients with certain cardiac conditions were excluded from the study along with patients taking certain medications. Study Results On all six scales, DMQ 45/30 mg was significantly superior to placebo, including the primary efficacy analysis, which utilized mixed-effects modeling to test all scores on an 11-point numerical Pain Rating Scale (p < 0.0001). Sensitivity analyses gave consistent results. Efficacy versus placebo was also seen for diary ratings of present pain intensity, and pain interference with sleep and with activities (all p < 0.0001). Among clinic-visit assessments, DMQ 45/30 mg demonstrated greater leg-pain relief (p = 0.0002) and greater reduction of leg-pain intensity (p = 0.0286) versus placebo. The efficacy of DMQ 30/30 mg was numerically less than for 45/30 mg but for most outcomes remained significantly greater versus placebo. Adverse events were mostly mild or moderate and of expected types. Discontinuation for adverse events in the DMQ groups was at least twice as common as placebo.