Micelles-in-Liposome Systems Obtained by Proliposomal Approach for Cannabidiol Delivery: Structural Features and Skin Penetration

Deformable liposomes represent valuable drug carriers for cutaneous administration. Nevertheless, the fluid lipid membrane can favor the drug leakage during storage. Proliposomes may represent a suitable strategy to solve this issue. As an alternative, a novel carrier, which encloses hydrophobic drugs in the inner core of vesicles, namely, a drug-in-micelles-in-liposome system (DiMiL), has been proposed. In this work, we investigated the possible advantages of combining these two approaches to obtain a formulation able to enhance the skin penetration of cannabidiol (CBD). Proliposomes were prepared by spray-drying or slurry method testing lactose, sucrose, and trehalose as carriers at different sugar/lipid weight ratios. The ratio between soy-phosphatidylcholine (main lipid) and Tween 80 was instead fixed at 85:15 w/w. DiMiL systems were extemporaneously obtained by the hydration of proliposomes with a Kolliphor HS 15 micellar dispersion (containing CBD, when appropriate). Based on the technological properties, sucrose and trehalose at 2:1 sugar/lipid ratio resulted in the best carriers for spray-dried and "slurried" proliposomes, respectively. Cryo-EM images clearly showed the presence of micelles in the aqueous core of lipid vesicles and the presence of sugars did not alter the structural organization of DiMiL systems, as demonstrated by SAXS analyses. All formulations were highly deformable and able to control CBD release regardless of the presence of sugar. The permeation through human epidermis of CBD carried by DiMiL systems was significantly improved compared to that obtained loading the drug in conventional deformable liposomes with the same lipid composition or in an oil solution. Furthermore, the presence of trehalose led to a further slight increase of the flux. Altogether, these results demonstrated that proliposomes may be a valuable intermediate for the preparation of deformable liposome-based cutaneous dosage forms, improving the stability without compromising the overall performances.