Objectives. To confirm the efficacy, tolerability, and safety of NGX-4010, an 8% capsaicin dermal patch (capsaicin 640 µg/cm2), 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/cm2) 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.