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IDSA 2011: Capsaicin Patch Reduces Pain Due to HIV-Associated Neuropathy

A patch containing 8% capsaicin -- a compound derived from chili peppers -- significantly relieved the pain of nerve damage related to HIV or its treatment, investigators reported at the 49th Annual Meeting of the Infectious Diseases Society of America (IDSA 2011) last month in Boston.

HIV-associated neuropathy typically affects the feet and sometimes the lower legs or hands, causing pain or burning sensations that can potentially be debilitating. Some older nucleoside reverse transcriptase inhibitors (NRTIs) -- notably didanosine (ddI; Videx), stavudine (d4T; Zerit), and zidovudine (AZT; Retrovir) -- caused neuropathy thought to be related to mitochondrial toxicity. HIV infection itself or resulting inflammation may also contribute to nerve damage.

HIV-associated neuropathy does not always respond well to opiates and other oral pain medications, which can also have unwanted side effects. There are currently no treatments FDA-approved specifically for this condition.

Stephen Brown of the AIDS Research Alliance of West Hollywood and colleagues conducted a study of NGX-4010 (brand name Qutenza), a capsaicin patch developed by NeurogesX that is approved in the U.S. for management of nerve pain associated with post-herpetic neuralgia following shingles outbreaks.

NGX-4010 was tested in 2 randomized, double-blind, controlled trials of patients with painful HIV-associated neuropathy. The 2 studies combined included 239 participants who received a single 30-minute treatment with the 8% capsaicin NGX-4010 patch, and 100 control subjects who received a 0.04% capsaicin patch, a dose too low to be effective.

Participants recorded their average pain for the past 24 hours each day for 12 weeks using the Neuropathic Pain Rating Scale (NPRS), and completed the Patient Global Impression of Change (PGIC) scale at the conclusion of the study.

Results

• During weeks 2-12 after application, patients who received the NGX-4010 patch reported significantly lower NPRS scores compared with people who used the control patch (27% vs 16%, respectively).
• 39% of patients in the NGX-4010 arm reported a response compared with 23% in the control arm, a significant difference.
• At the end of the study, 36% of patients who used the NGX-4010 patch reported being much or very much improved on the PGIC scale, compared with 22% in the control arm, again a significant difference.
• NGX-4010 efficacy was superior to placebo regardless of sex, baseline pain score, or duration of neuropathy.
• NGX-4010 efficacy was also evident for patients who used additional neuropathic pain medications, although treatment differences were greater for those who used NGX-4010 alone.
• The most common adverse event was transient mild-to-moderate pain and redness at the patch application site.

Based on these findings, the investigators concluded, "These integrated analyses show that a single 30-minute NGX-4010 application can reduce neuropathic pain due to HIV-associated neuropathy for 12 weeks and is well tolerated."

This fall NeurogesX submitted a supplemental New Drug Application to the FDA seeking an additional indication for the Qutenza  capsaicin patch for HIV-associated neuropathy.

Investigator affiliations: AIDS Research Alliance, West Hollywood, CA; Mount Sinai School of Medicine, New York, NY; Chelsea and Westminster Hospital, London, UK; St Vincent's Hospital, Darlinghurst, Australia; University of Rochester, Rochester, NY; St Thomas' Hospital, London, UK; Barts and the London NHS Trust, London, UK; HIV/GUM Research Department, Elton John Centre, Brighton and Sussex University Hospitals NHS Trust, Brighton, UK; NeurogesX, Inc, San Mateo, CA.

11/4/11

Reference

S Brown, D Simpson, G Moyle, et al. Efficacy of NGX-4010 (Qutenza), a Capsaicin 8% Patch, Applied for 30 Minutes in Patients with HIV-Associated Neuropathy: Results of Integrated Analyses. 49th Annual Meeting of the Infectious Diseases Society of America (IDSA 2011). Boston, October 20-23, 2011. Abstract 449.