Capsaicin 8% Patch Repeat Treatment in Non-diabetic Peripheral Neuropathic Pain: A 52-week, Open-label, Single-arm, Safety Study.

OBJECTIVES: To investigate long-term safety and tolerability of capsaicin 8% patch repeat treatment in non-diabetic patients with peripheral neuropathic pain (NP).

METHODS: Prospective, open-label, observational study in patients with post-herpetic neuralgia, post-traumatic or post-surgical nerve injury, HIV-associated distal sensory polyneuropathy, or other peripheral NP, and average daily pain score ≥4, received ≤6 capsaicin 8% patch treatments over 52 weeks according to clinical need (retreatment at 9-12 wk intervals). Sensory testing and analgesic effectiveness were assessed using "bedside tests" and Brief Pain Inventory (question 5).

RESULTS: Overall, 306 patients received treatment. Treatment-emergent adverse events (TEAE) and drug-related TEAEs were reported by 252 (82.4%) and 207 (67.6%) patients. Application site pain was the most common drug-related TEAE (n=112, 36.6%); no drug-related serious TEAEs were reported. Sensory category shift analyses from baseline to end of study (EoS) in patients attending at least two sensory visits (n=278 for all tests except warm, n=277) found sensory deterioration/loss in at least one modality in 50.4% (n=140); deterioration/loss in one, two, three, four or five modalities occurred in 26.6% (n=74), 14.0% (n=39), 5.8% (n=16), 2.5% (n=7) and 1.4% (n=4). Newly emergent hyperaesthesia or allodynia was apparent in 1.1-3.6% (depending on modality) by EoS. Between 25.2 and 32.0% of patients reported improvement in a sensory modality by EoS. Average daily pain was 6.6 and 4.7 at baseline and Month 12.

CONCLUSIONS: Generally, capsaicin 8% patch repeat treatment over 52 weeks was well tolerated, with variable alteration in sensory function and minimal chance of complete sensory loss.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially. https://creativecommons.org/licenses/by-nc-nd/4.0.