Qutenza 8% Capsaicin Topical System for the Treatment of Neuropathic Axial Lower Back Pain and Lumbosacral Radiculopathy

Chronic lower back pain (LBP) and lumbosacral radiculopathy are common, disabling, and costly conditions. The lifetime prevalence of LBP is estimated to be greater than 70% in industrialized countries, with a 1-year prevalence of 15-45% and LBP is the most common cause of years lived with disability worldwide. Chronic LBP (defined as LBP lasting less than 3 months) is a complex and heterogeneous condition with nociceptive and neuropathic components.

The goals of treatment of chronic LBP and lumbosacral radiculopathy are to reduce pain, maintain function, and prevent future exacerbation. Guidelines advocate for a multimodal approach to the management of these conditions, combining pharmacological therapies for symptomatic relief with nonpharmacological approaches, such as physical rehabilitation. Choice of treatment is individualized according to the nature and severity of symptoms, the presence of comorbid conditions, potential for adverse effects and drug interactions, and cost. At this time, there are no specific recommendations for treatment of the neuropathic components of chronic LBP and neuropathic pain medications for painful radiculopathy have limited response rates. Furthermore, current pharmacologic approaches for the treatment of neuropathic pain are associated with a risk of significant adverse effects, which can have a serious impact on patients' quality of life. As such, there is a pressing need for safe and effective therapeutic options in treating neuropathic LBP and painful lumbosacral radiculopathy.

Capsaicin is the main compound in chili peppers and acts mechanistically as a selective agonist of the transient receptor potential vanilloid 1 (TRPV1) channel, which is highly expressed on nociceptors. High concentrations of capsaicin have been effectively utilized for the treatment of neuropathic pain. Additionally, whereas many pharmacologic and interventional pain relief options for chronic LBP and radiculopathy cause weight gain, capsaicin has been widely studied for its weight loss potential.

Emerging evidence suggests the use of topical capsaicin may be a safe and efficacious treatment for chronic LBP and radiculopathy. With regards to LBP, a 2010 double-blind multi-center randomized clinical trial on the use of 0.05% topical capsaicin cream for the treatment of chronic LBP demonstrated a significantly higher number of patients experiencing at least 50% pain sum score improvement at 3 weeks compared to placebo. A 2016 open-label study of 90 patients with lumbosacral neuropathic pain who received treatment with a topical 8% capsaicin patch found statistically significant reductions in pain at 2, 8, and 12 weeks follow-up. With regards to lumbosacral radiculopathy, a 2017 randomized controlled trial of 50 participants with chronic lumbosacral radiculopathy treated with a topical 8% capsaicin patch found at least a 30% improvement of pain in 71.4% and 39.1% of patients with 3 months to 2 years duration of pain and greater than 2 years duration of pain, respectively. A prospective study investigating the use of a single 8% capsaicin patch in patients with a variety of neuropathic pain conditions, including radiculopathy noted that the proportions of patients achieving a 30% and 50% decrease in pain at 12 weeks were 43% and 24%, respectively. Additionally, a small retrospective analysis of patients with painful radiculopathy found that the capsaicin 8% patch provided rapid and sustained pain relief, with a significant reduction in prescribed concomitant pain medications. In brief, the current literature is limited by small sample sizes and short follow up periods but does suggest topical capsaicin is a rational choice for the treatment of neuropathic lumbosacral pain.