Capsaicin 8% Patch Safe for Peripheral Neuropathic Pain
The capsaicin patch allows for “significant systemic absorption [and] limits the potential for drug-drug interactions.”
The use of capsaicin 8% patch repeat treatment is well tolerated and may provide effective long-term benefit in patients with peripheral neuropathic pain, according to an open-label, prospective, observational study published in The Clinical Journal of Pain.1
Investigators analyzed treatment-emergent adverse events (TEAEs) and drug-related TEAEs in nondiabetic patients receiving up to 6 capsaicin 8% patch treatments over a 52-week period for post-herpetic neuralgia, HIV-associated distal sensory polyneuropathy, posttraumatic or postsurgical nerve injury, and peripheral neuropathic pain. The average daily pain score was ≥4, and retreatment occurred at 9- to 12-week intervals, depending upon clinical need.
Of 306 patients receiving treatment, TEAEs and drug-related TEAEs were observed in 252 (82.4%) and 207 (67.6%) patients, respectively. The most frequent drug-related TEAE was application site pain (n=112, 36.6%).
Sensory category shift analyses conducted from baseline to the end of the study, allowed to detect sensory deterioration/loss in up to 1 modality in 140 patients (50.4%) and deterioration/loss in 1, 2, 3, 4, or 5 modalities in 74 (26.6%), 39 (14.0%), 16 (5.8%), 7 (2.5%), and 4 (1.4%) patients, respectively. Depending on the modality, new cases of hyperesthesia or allodynia were observed in 1.1% to 3.6% of cases by the end of the study. Improvement in sensory modality by the end of the study was observed in 25.2% to 32.0% of patients. In addition, researchers found that the average daily pain level, as assessed by question 5 in the Brief Pain Inventory, was 6.6 at baseline and 4.7 at 12 months.
According to the researchers, the use of capsaicin may also be well tolerated in other patient populations, as this therapy reduces “significant systemic absorption [and] limits the potential for drug-drug interactions or the need for dose adjustment in the elderly or patients with hepatic or renal impairment.”
Considering that this phase IV study had an open-label design and patients knew which treatments they were receiving, there is potential for the placebo effect to have played a role in the findings.
- Gálvez R, Navez ML, Moyle G, et al. Capsaicin 8% patch repeat treatment in nondiabetic peripheral neuropathic pain: a 52-week, open-label, single-arm, safety study. Clin J Pain. 2017;33(10):921-931.