High-concentration Capsaicin Patch Is Beneficial for Treatment of Painful HIV-related Neuropathy

HIV-associated distal sensory polyneuropathy, a form of peripheral neuropathy, is a painful condition with limited effective treatment. One therapy under study is capsaicin, derived from hot peppers, which desensitizes cutaneous nociceptors (pain receptors in the skin), resulting in reduced pain.

In the June 10, 2008 issue of Neurology, researchers at the Mount Sinai Medical Center in New York City reported results of a placebo-controlled study of a high-concentration capsaicin dermal patch (NGX-4010) for the treatment of painful neuropathy.

In this double-blind multicenter study, the investigators randomized 307 patients with painful HIV-related distal sensory polyneuropathy to receive NGX-4010 or a control low-concentration capsaicin patch. After application of a topical anesthetic, NGX-4010 or the control patch was applied once for 30, 60, or 90 minutes to painful areas on the feet.

The primary efficacy endpoint was percent change from baseline in mean Numeric Pain Rating Scale "average pain for past 24 hours" scores from weeks 2 through 12.

Results

• A single NGX-4010 application resulted in a mean pain reduction of 22.8% during weeks 2 through 12, as compared with a 10.7% reduction for the control patch (P = 0.0026).

• Following a transient treatment-related pain increase, neuropathy pain was reduced.

• Significant improvement in pain was apparent by week 2 and continued throughout the 12-week observation period.

• Mean pain reductions in participants receiving NGX-4010 were:

• 27.7% in the 30 minute group (P = 0.0007 vs control group);

• 15.9% in the 60 minute group (P = 0.287);

• 24.7% in the 90 minute group (P = 0.0046).

• One-third of patients treated with NGX-4010 reported a 30% or greater decrease in pain from baseline, compared with 18% of controls (P = 0.0092).

• Self-limited mild-to-moderate local skin reactions were commonly observed.

In conclusion, the authors wrote, "A single NGX-4010 application was safe and provided at least 12 weeks of pain reduction in patients with HIV-associated distal sensory polyneuropathy. These results suggest that NGX-4010 could provide a promising new treatment for painful HIV neuropathy."

Clinical Neurophysiology Laboratories and Neuro-AIDS Program, Mount Sinai Medical Center, New York, NY; AIDS Research Alliance, West Hollywood, CA; NeurogesX, Inc., San Carlos, CA.

6/17/08

Reference

DM Simpson, S Brown, J Tobias, and others. (NGX-4010 C107 Study Group: 31Collaborators). Controlled trial of high-concentration capsaicin patch for treatment of painful HIV neuropathy. Neurology 70(24): 2305-2313. June 10, 2008.

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