Capsaicin for Neuropathic Pain: Linking Traditional Medicine and Molecular Biology

Abstract

Capsaicin has long been used as a traditional medicine to treat pain and, recently, its mechanism of analgesic action has been discovered. This review article documents the clinical development of capsaicin to demonstrate that pharmacognosy still has a profound influence on modern-day drug development programs. Capsaicin is a highly selective agonist for the transient receptor potential channel vanilloid-receptor type 1 (TRPV1), which is expressed on central and peripheral terminals of nociceptive primary sensory neurons. Knockout studies have revealed the importance of TRPV1 as a molecular pain integrator and target for novel analgesic agents. Topical application of capsaicin at the peripheral terminal of TRPV1-expressing neurons superficially denervates the epidermis in humans in a highly selective manner and results in hypoalgesia. In three recent randomized controlled trials, a patch containing high-concentration capsaicin demonstrated meaningful efficacy and tolerability relative to a low-concentration capsaicin control patch in patients with peripheral neuropathic pain. Data from clinical practice will determine if the high-concentration capsaicin patch is effective in real-world settings.

High concentration capsaicin for treatment of peripheral neuropathic pain: effect on somatosensory symptoms and identification of treatment responders

“…At single symptom level a weak association was found between burning and pressure-evoked pain at baseline and response. Since the burning quality is frequently associated with the presence of TRPV1 receptors on nociceptors this association is in line with the proposed mechanism of action of capsaicin 21 .…”

Capsaicin Used on Skin Influences Ion Transport Pathways: An in vitro Study

“…Capsaicin (8-methyl-N-vanillyl-6-nonenamide), a lipophilic alkaloid found in hot red chili peppers of the genus Capsicum (hot chili peppers), has long been used to treat persistent pain, such as osteoarthritic pain, postherpetic neuralgia of the trigeminal nerve, cluster headache, diabetic neuropathy, HIV-associated distal sensory neuropathy, and intractable pain in cancer patients [1,2,3,4,5,6,7,8,9,10,11,12]. Capsaicin is an agonist of transient receptor potential cation channel, subfamily V, member 1 (TRPV1), which provides the sensation of pain (nociception).…”

Plant-Derived Anti-Inflammatory Compounds: Hopes and Disappointments regarding the Translation of Preclinical Knowledge into Clinical Progress

“…It is activated by chemical and physical stimuli, such as heat, low pH, capsaicin, and certain inflammatory mediators [57]. Prolonged activation of TRPV1 by capsaicin is discussed to cause desensitization and, thus, reduced pain sensation [58]. Beyond pain, some few studies also found an anti-inflammatory potential of capsaicin: it can inhibit paw inflammation in arthritic rats [59] and ethanol-induced inflammation of the gastric mucosa in rats [60].…”