A primer on cannabis for cosmeceuticals: The endocannabinoid system
The endocannabinoid system and skin health
The endogenous cannabinoid or endocannabinoid system includes cannabinoid receptors, associated endogenous ligands (such as arachidonoyl ethanolamide [anandamide or AEA], 2-arachidonoyl glycerol [2-AG], and N-palmitoylethanolamide [PEA], a fatty acid amide that enhances AEA activity),2 and enzymes involved in endocannabinoid production and decay.11,15,22,23 Research in recent years appears to support the notion that the endocannabinoid system plays an important role in skin health, as its dysregulation has been linked to atopic dermatitis, psoriasis, scleroderma, and skin cancer. Data indicate that exogenous and endogenous cannabinoids influence the endocannabinoid system through cannabinoid receptors, transient receptor potential channels (TRPs), and peroxisome proliferator–activated receptors (PPARs). Río et al. suggest that the dynamism of the endocannabinoid system buttresses the targeting of multiple endpoints for therapeutic success with cannabinoids rather than the one-disease-one-target approach.24 Endogenous cannabinoids, such as arachidonoyl ethanolamide and 2-arachidonoylglycerol, are now thought to be significant mediators in the skin.3 Further, endocannabinoids have been shown to deliver analgesia to the skin, at the spinal and supraspinal levels.25
Anti-inflammatory activity
In 2010, Tubaro et al. used the Croton oil mouse ear dermatitis assay to study the in vivo topical anti-inflammatory effects of seven phytocannabinoids and their related cannabivarins (nonpsychoactive cannabinoids). They found that anti-inflammatory activity was derived from the involvement of the cannabinoid receptors as well as the inflammatory endpoints that the phytocannabinoids targeted.26
In 2013, Gaffal et al. explored the anti-inflammatory activity of topical THC in dinitrofluorobenzene-mediated allergic contact dermatitis independent of CB1/2 receptors by using wild-type and CB1/2 receptor-deficient mice. The researchers found that topically applied THC reduced contact allergic ear edema and myeloid immune cell infiltration in both groups of mice. They concluded that such a decline in inflammation resulted from mitigating the keratinocyte-derived proinflammatory mediators that direct myeloid immune cell infiltration independent of CB1/2 receptors, and positions cannabinoids well for future use in treating inflammatory cutaneous conditions.20
Literature reviews
In a 2018 literature review on the uses of cannabinoids for cutaneous disorders, Eagleston et al. determined that preclinical data on cannabinoids reveal the potential to treat acne, allergic contact dermatitis, asteatotic dermatitis, atopic dermatitis, hidradenitis suppurativa, Kaposi sarcoma, pruritus, psoriasis, skin cancer, and the skin symptoms of systemic sclerosis. They caution, though, that more preclinical work is necessary along with randomized, controlled trials with sufficiently large sample sizes to establish the safety and efficacy of cannabinoids to treat skin conditions.27
A literature review by Marks and Friedman published later that year on the therapeutic potential of phytocannabinoids, endocannabinoids, and synthetic cannabinoids in managing skin disorders revealed the same findings regarding the cutaneous conditions associated with these compounds. The authors noted, though, that while the preponderance of articles highlight the efficacy of cannabinoids in treating inflammatory and neoplastic cutaneous conditions, some reports indicate proinflammatory and proneoplastic activities of cannabinoids. Like Eagleston et al., they call for additional studies.28
Conclusion
As in many botanical agents that I cover in this column, cannabis is associated with numerous medical benefits. I am encouraged to see expanding legalization of medical marijuana and increased research into its reputedly broad potential to improve human health. Anecdotally, I have heard stunning reports from patients about amelioration of joint and back pain as well as relief from other inflammatory symptoms. Discovery and elucidation of the endogenous cannabinoid system is a recent development. Research on its functions and roles in cutaneous health has followed suit and is steadily increasing. Particular skin conditions for which cannabis and cannabinoids may be indicated will be the focus of the next column.
