Efficacy, safety, and tolerability of NGX-4010, capsaicin 8% patch, in an open-label study of patients with peripheral neuropathic pain

AimsTo assess efficacy, safety, and tolerability of NGX-4010, capsaicin 8% patch, in patients with peripheral neuropathic pain.MethodsThis open-label, uncontrolled, 12-week study enrolled 25 patients with postherpetic neuralgia (PHN), one with HIV-distal sensory polyneuropathy, and 91 with painful diabetic neuropathy (PDN). Patients received pre-treatment with one of three 4% lidocaine topical anesthetics (L.M.X.41, Topicaine Gel2, or Betacaine Enhanced Gel 43) followed by a single 60- or 90-min NGX-4010 application. The primary efficacy variable was the percentage change in Numeric Pain Rating Scale scores from baseline to Weeks 2–12. Adverse events (AEs), laboratory parameters, vital signs, neurosensory examinations, dermal assessments, treatment-related pain scores, and medication use for treatment-related pain were collected.ResultsPDN and PHN patients achieved a 31% and 28% mean pain decrease from baseline during Weeks 2–12, respectively, and 47% and 44%, respectively, were responders (≥30% pain decrease). Mild or moderate treatment-site-related burning and pain were the most common AEs and there was no evidence of impaired neurosensory function.ConclusionsNGX-4010 in conjunction with any of the three topical anesthetics tested was generally safe and well tolerated and reduced pain over a 12-week period in patients with PDN and PHN.