Topical administration of cannabidiol: Influence of vehicle-related aspects on skin permeation process

Cannabidiol (CBD) is a non-psychoactive cannabinoid isolated from Cannabis sativa which, given its claimed beneficial properties and therapeutic potential, has lately aroused considerable attention from the scientific community. Starting from the little literature evidence, the main purpose of this study was to investigate the topical administration of CBD, with particular focus on the influence of vehicle-related aspects on the skin permeation process. This could provide useful information for the design of suitable drug delivery systems which could be used in developing topical medicines and cosmetics. In vitro human skin permeation studies were conducted using modified Franz diffusion cells to compare the performance of four solutions and two semisolid formulations. The Hildebrand solubility parameter was used to better understand the thermodynamic aspects implied in the partitioning process of the cannabinoid compound into the skin. It was interestingly found that a hydrophilic gel, mostly consisting of propylene glycol (79%, w/w), can be an optimal choice for the topical administration of CBD. Moreover, the feasibility of the preparation of CBD-loaded (trans)dermal patches, made with new printing technology, was also demonstrated.