Conclusion
Data from artificial membrane-based assays support that CBD is a skin permeable cannabinoid and the permeability and stability of its formulations may be influenced by several factors such as surfactant and pH environment. Findings from our study suggest that CBD may have suitable skin permeability for the development of dermatological and/or cosmeceutical applications but further studies using in vivo models are warranted to confirm this.
Methods
CBD and two CBD-incorporated topical formulations (cream and gel) were prepared for this study. Computational predictions (SwissADME and DERMWIN™) and the parallel artificial membrane permeability assay (PAMPA) were used to evaluate the skin permeability of CBD isolate. The Franz cell diffusion (in vitro release testing) assay was used to evaluate the skin permeability of CBD formulations. The solubility and stability of CBD in surfactants were assessed by high-performance liquid chromatography and mass spectrometry analysis.
Results
CBD isolate showed favorable skin permeability in the SwissADME and DERMWIN™ predictions (-Log Kp of 3.6 and 5.7 cm/s, respectively) and PAMPA (-LogPe value of 5.0 at pH of 6.5 and 7.4). In addition, CBD had higher solubility (378.4 μg/mL) in surfactant Tween 20 as compared to its solubility in polyisobutene. In an acidic environment (pH 5 and 6), Tween 20 maintained the CBD content at 81% and 70% over 30 days, respectively. CBD in the formulations of cream and gel also had moderate skin permeability in the Franz cell diffusion assay.