Capsaicin: A review of its pharmacology and clinical applications

SummaryCapsaicin is a naturally occurring alkaloid derived from chillies that is responsible for its hot pungent taste. It is an odourless fat soluble compound that is rapidly absorbed through the skin. Capsaicin is thought to produce analgesia by depleting substance P in small fibre nociceptor neurons on which Transient Receptor Potential action channel (subfamily V), type 1 (TRPV1) is predominantly located. It binds to the vanilloid receptor TRPV1, which acts as a molecular integrator of chemical and physical painful stimuli.Topically applied capsaicin is useful in alleviating pain associated with diabetic neuropathy and chronic musculoskeletal pain. It is used to increase the bladder capacity and reduce incontinence in patients with bladder hyperactivity. Capsaicin can reduce post-operative nausea and vomiting when applied at acupressure points. It may be used to treat pruritis associated with renal failure and protect the stomach against non-steroidal anti-inflammatory drug induced gastritis. The development of capsaicin analogues and TRPV1 antagonists may provide more effective and better tolerated therapeutic agents in the future. Synthetic agents that are less pungent and target the TRPV1 receptor may prove to be more efficacious and more tolerable than naturally occurring capsaicin for the treatment of pain and inflammatory disease states.