The multi-center study will be conducted in more than 50 US sites recruiting around 400 patients. One-half of the postherpetic neuralgia (PHN) patients will be assigned to receive NGX-4010 for 60 minutes. The other half of the study participants will receive a control patch containing a very low concentration of capsaicin, also for 60 minutes.
Assignments will be randomized with both physician and patients blinded to which type of patch is received. Following this single-treatment, patients will record their pain scores daily in personal diaries using a scale of 0 (no pain) to 10 (worst possible pain). The primary endpoint of this study is percent change in average pain level from baseline to weeks two to eight.
“Postherpetic neuralgia, which is chronic pain persisting after a shingles outbreak, is a debilitating disease that represents a large unmet medical need,” said John Jermano, NeurogesX director of clinical research. “NGX-4010 may prove to have significant advantages over oral PHN treatments that have considerable side effects such as drowsiness or constipation.”
Last month, NeurogesX announced positive phase II results for NGX-4010 in painful HIV-associated sensory neuropathy (HIV-AN). The company has been granted fast track status as well as orphan drug designation for NGX-4010 in HIV-AN by the FDA.
NGX-4010 is a topical, physician-administered patch containing a high concentration of trans-capsaicin, a synthetic form of the naturally occurring capsaicin and the ingredient that makes chili peppers hot. The patch is designed to act peripherally, or in the skin, where the pain frequently originates, unlike current treatment approaches for neuropathic pain that include opioids and other agents acting on the central nervous system that can cause drowsiness or other systemic side effects.