A multicenter, randomized, double-blind, controlled study of NGX-4010, a high-concentration capsaicin patch, for the treatment of postherpetic neuralgia.

Objectives: To confirm the efficacy, tolerability, and safety of NGX-4010, an 8% capsaicin dermal patch (capsaicin 640 µg/cm(2) ), in patients with postherpetic neuralgia (PHN). PHN is a chronic pain disorder that can be difficult to treat and for which current treatment options are often limited by poor tolerability.

Design: A total of 418 patients were randomized to receive a single 60-minute application of NGX-4010 or a 0.04% capsaicin control patch (3.2 µg/cm(2) ) in a multicenter, double-blind, confirmatory, phase 3 study.

Patients: Patients were 18-90 years old with a diagnosis of PHN, pain for at least 6 months, and an average baseline Numeric Pain Rating Scale (NPRS) score of 3-9.

Outcome Measures: The primary efficacy end point was the percentage change in NPRS score from baseline to weeks 2-8.

Results: NGX-4010 recipients had a significantly greater mean reduction from baseline in pain during weeks 2-8 compared with the control group (32.0% vs 24.4%; P=0.011). A ≥ 30% reduction in mean NPRS scores was achieved in 46% of NGX-4010 recipients compared with 34% of controls (P=0.02). Pain was significantly lower in NGX-4010 recipients than controls by week 2, and greater pain reduction was maintained throughout the remaining 12-week study period. Most treatment-emergent adverse events were application site specific (notably erythema and pain), transient, and generally mild to moderate in severity.

Conclusions: In patients with PHN, a single 60-minute application of NGX-4010 produced significant reduction in pain that was maintained over a 12-week period.