Capsaicin 8% Patch for Spinal Cord Injury Focal Neuropathic Pain, a Randomized Controlled Trial

Abstract

Background Neuropathic pain (NP) after spinal cord injury (SCI) exacerbates disability, decreases quality of life (QOL) and is often refractory to available therapies. Patients report willingness to trade potential recovery of strength, bowel, bladder, or sexual function for pain relief. One proposed mechanism causing NP is up-regulation of transient receptor potential vanilloid 1 (TRPV 1) proteins in uninjured C fibers and dorsal root ganglia causing neuronal excitability. Recent studies have found up-regulation of TRPV 1 proteins after SCI. Objective We hypothesize the application of Capsaicin 8% patch (C8P), FDA approved for NP in diabetic peripheral neuropathy and post herpetic neuralgia, will improve pain, function and QOL in persons with SCI. Design/Methods Randomized single-blind crossover design in which 11 persons with SCI and NP refractory to two oral pain medications received C8P or a control low dose Capsaicin 0.025% patch (CON) over two 12-week periods. Pain (VAS, MPI-SCI), quality of life (WHO-QOL), and functional status (SCIM) were measured at 2–4-week intervals. Results There was a main treatment effect of C8P over CON on VAS and MPI-SCI outcomes with pain reduction of 35% and 29% at weeks 2 and 4 respectively. C8P also demonstrated a main treatment effect over CON on the SCIM mobility subscale. WHO-QOL scores did not improve with C8P. Conclusion C8P improves pain and mobility for patients with SCI and refractory NP. Larger studies should be performed to evaluate impact of repeat applications and QOL outcomes.

Novel Drug Targets and Emerging Pharmacotherapies in Neuropathic Pain

“…The capsaicin 8% patch provided effective pain relief with reduced application frequency and minimal systemic side effects compared to oral medications, like gabapentinoids or TCAs, in patients with painful diabetic peripheral neuropathy [ 99 ]. In a randomized controlled trial, the application of the capsaicin 8% patch for neuropathic pain in individuals with spinal cord injury was investigated, showing significant pain reduction, with improvements observed for pain outcome and mobility, but not in quality of life, measures [ 100 ]. In a systematic review of 5 studies including 95 patients, the efficacy and tolerability of 8% capsaicin patch was evaluated for its effectivess in mitigating the effects of chemotherapy-induced peripheral neuropathy, providing significant pain relief [ 101 ].…”

Perineural Invasion in Pancreatic Ductal Adenocarcinoma: From Molecules towards Drugs of Clinical Relevance

“…In an animal study, the activation of TRPV1 in the spinal cord by capsaicin produced excessive glutamate liberation causing acute pain [ 108 ]. A randomized control trial on patients affected by neuropathic pain reported a reduction of pain after treatment with capsaicin patches [ 109 ]. Mice treated with the endocannabinoid-like molecule palmitoylethanolamide (PEA) showed a decrease in pain derived from peripheral neuropathy, while using synthetic antagonists to block PPAR-α and CB1 receptors reversed this effect, demonstrating the mediation of these receptors in this process [ 110 ].…”

A Silver Lining of Neuropathic Pain: Predicting Favorable Functional Outcome in Spinal Cord Injury

“…Spinal cord injury (SCI) is a debilitating condition which often leads to long-term or permanent mobility disability, chronic risk of various complications, and requires extensive medical resources. 1 , 2 An epidemiology study showed that the overall global incidence of SCI was 10.5 cases per 100,000 persons. 3 Although mobility is the most critical factor determining functional outcome, 4 additional sequelae such as neuropathic pain (NP), bladder and rectum dysfunctions also decrease quality of life considerably.…”