BioSpace reports on the results of a phase III, randomised, controlled, double blind, multicentre study published in the February issue of the journal “Pain Medicine” which investigated the efficacy and safety of a fixed dose combination product containing dextromethorphan (DM) and quinidine (Q), also known as AVP-923, at two dosage levels for diabetic neuropathic pain. The findings suggest that AVP-923 was effective for the treatment of diabetic peripheral neuropathy (DPN), with an acceptable safety profile.

In the 13-week, study 379 adults with daily symmetric 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. Certain exclusion criteria applied to the study and included exclusion of patients with certain cardiac conditions. The results found (direct from source):

• On all six pain rating scales, DMQ 45/30 mg was better than placebo, including the primary efficacy analysis, which used mixed-effects modelling to test all scores on an 11-point numerical Pain Rating Scale (p < 0.0001). Sensitivity analyses provided 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 better than 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.

Note: No further study details are available in the BioSpace story. The online February issue of the journal was unavailable at time of writing.