Treatment of neuropathic pain remains an enigmatic dilemma for most physicians.  Presently there are no drugs FDA approved for central neuropathic pain.  The use of drugs utilized for diabetic peripheral neuropathy and fibromyalgia, most notably Cymbalta (Eli Lilly), Lyrica (Pfizer) and Savella (Forest), as well as generics such as  gabapentin, tricyclic antidepressants and older anticonvulsants remain the mainstay of therapy.
Central neuropathic pain remains relatively treatment resistant, with most patients not achieving more than 30% pain relief.  Many patients with traumatic spinal cord injury with severe neuropathic pain choose no pain medication, given the minimal effect and high side effects of conventional (non-intrathecal) medications.  This double blind placebo controlled trial of Cymbalta (duloxetine, Eli Lilly) in patients with central neuropathic pain secondary to spinal cord injury or stroke, while showing a trend favoring Cymbalta, failed to show a statistically significant result for the primary endpoint.
The absence of a statistically significant endpoint means no clinically meaningful result, and no new label.
Nuedexta, Avanir's combination of ultra-low dose (10mg) quinidine with 20 mg of dextromethorphan showed a robust and rapid response in multiple sclerosis patient's with central neuropathic pain.  Although recently approved for PBA (Pseudobulbar affect), the effect seen in central neuropathic pain in MS patients was dramatic, and in additive to that achieved by concomitant use of narcotic or non-narcotic analgesics.  Avanir has released similar exemplary data for patients suffering diabetic peripheral neuropathy.
Central neuropathic pain remains an open field.  There are presently no drugs FDA approved for central neuropathic pain in the US, and only one (Lyrica) outside the US. With the upcoming launch of Nuedexta for PBA, and the positive data seen previously in double blind placebo controlled trials in MS pain, one can only hope that Avanir will follow Eli Lilly and soon fund trials in central neuropathic pain.  A successful trial of Nuedexta in central neuropathic pain could be expected to add markedly to Avanir's valuation.