December 5, 2017
October 27, 2017
Topical cannabinoids are increasingly utilized by dermatology patients for a range of disorders; however, the acceptance of these over-the-counter products has far outpaced scientific investigation into their safety and efficacy. Here, we review the studies of topical cannabinoids in skin conditions and assess their current place in dermatology practice.
Cannabis is designated as a Schedule I drug, according to the Controlled Substances Act of 1970. This listing is given to substances with no therapeutic value and a high potential for abuse. However, as of 2017, 29 states and the District of Columbia have laws legalizing cannabis in some capacity. These regulations typically apply to medicinal use, though several states have now legalized recreational use.
Cannabinoids represent a broad class of chemical compounds derived from the cannabis plant. Originally, this class only comprised phytocannabinoids, cannabinoids produced by the cannabis plant. Tetrahydrocannabinol (THC) is the most well-known phytocannabinoid and leads to the psychoactive effects typically associated with cannabis use. Later investigation led to the discovery of endocannabinoids, cannabinoids that are naturally produced by human and animal bodies, as well as synthetic cannabinoids.1Cannabidiol is a phytocannabinoid that has been investigated in neurologic and anti-inflammatory conditions.2-4
Cannabinoids act as agonists on 2 principal receptors— cannabinoid receptor type 1 (CB1) and cannabinoid receptor type 2 (CB2)—which are both G protein–coupled receptors (Figure).5 Both have distinct distributions throughout different organ systems, to which cannabinoids (eg, THC, cannabidiol, endocannabinoids) show differential binding.6,7Importantly, the expression of CB1 and CB2 has been identified on sensory nerve fibers, inflammatory cells, and adnexal structures of human skin.8 Based on these associations, topical application of cannabinoids has become a modality of interest for dermatological disorders. These formulations aim to influence cutaneous morphology without producing psychoactive effects.