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

Aims: To assess efficacy, safety, and tolerability of NGX-4010, capsaicin 8% patch, in patients with peripheral neuropathic pain.

Methods: This 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.

Results: PDN 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.

Conclusions: NGX-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.