In vitro percutaneous absorption studies of cannabidiol using human skin: Exploring the effect of drug concentration, chemical enhancers, and essential oils

Cannabidiol, a non-psychoactive constituent of cannabis, has garnered much attention after United States Food and Drug Administration approved Epidiolex (R) for oral use. Although therapeutic effect of cannabidiol after systemic absorption has been investigated extensively, its therapeutic potential in treating skin disorders after local delivery still needs further exploration. Our study has investigated the effect of cannabidiol concentration, chemical enhancers, and essential oils on percutaneous absorption of cannabidiol. In vitro permeation tests were conducted on human skin. The 24 h study results suggest no significant difference in amount of drug absorbed into skin, between 5% (242.41 +/- 12.17 mu g/cm(2)) and 10% (232.79 +/- 20.82 cm(2)) cannabidiol solutions. However, 1% delivered (23.02 +/- 4.74 mu g/cm(2)) significantly lower amount of drug into skin than 5% and 10%. Transcutol and isopropyl myristate did not enhance delivery of cannabidiol. However, oleic acid was found to be useful as chemical enhancer. Oleic acid (43.07 +/- 10.11 mu g/cm(2)) had significantly higher cannabidiol delivery into skin than the group without oleic acid (10.98 +/- 3.40 mu g/cm(2)) after a 4 h in vitro permeation study. Essential oils at concentrations tested had lower total cannabidiol delivery when compared to control. This study's findings will help guide future research on the pharmacological effect of percutaneously delivered cannabidiol on inflammatory skin disorders.