Introduction: Effective treatment of HIV-associated distal sensory polyneuropathy remains a significant unmet therapeutic need.
Methods: In this randomized, double-blind, controlled study, patients with pain due to HIV-associated distal sensory polyneuropathy received a single 30-minute or 60-minute application of NGX-4010—a capsaicin 8% patch (n = 332)—or a low-dose capsaicin (0.04%) control patch (n = 162). The primary endpoint was the mean percent change from baseline in Numeric Pain Rating Scale score to weeks 2–12. Secondary endpoints included patient global impression of change at week 12.
Results: Pain reduction was not significantly different between the total NGX-4010 group (−29.5%) and the total control group (−24.5%; P = 0.097). Greater pain reduction in the 60-minute (−30.0%) versus the 30-minute control group (−19.1%) prevented intended pooling of the control groups to test individual NGX-4010 treatment groups. No significant pain reduction was observed for the 30-minute NGX-4010 group compared with 30-minute control (−26.2% vs.−19.1%, respectively, P = 0.103). Pain reductions in the 60-minute NGX-4010 and control groups were comparable (−32.8% vs. −30.0%, respectively; P = 0.488). Posthoc nonparametric testing demonstrated significant differences favoring the total (P = 0.044) and 30-minute NGX-4010 groups (P = 0.035). Significantly, more patients in the total and 30-minute NGX-4010 group felt improved on the patient global impression of change versus control (67% vs. 55%, P = 0.011 and 65% vs. 45%, P = 0.006, respectively). Mild to moderate transient application site pain and erythema were the most common adverse events.
Conclusions: Although the primary endpoint analyses were not significant, trends toward pain improvement were observed after a single 30-minute NGX-4010 treatment.