Elastic liposomes-in-vehicle formulations destined for skin therapy: the synergy between type of liposomes and vehicle.

Objective: The present study is focused on optimization of elastic liposomes-in-vehicle formulations in respect to drug release and formulation properties. By combining penetration potential of elastic liposomes containing high ratio of entrapped drug and physicochemical properties of vehicles, both affecting the release and texture properties, optimal formulation could be achieved.

Materials And Methods: Deformable, propylene glycol-containing or conventional liposomes with hydrophilic model drug (diclofenac sodium) were incorporated into the following vehicles appropriate for skin application: a hydrogel, a cream base and derma membrane structure base cream (DMS base). Each formulation was assessed for in vitro drug release and mechanical properties.

Results And Discussion: The composition and type of both liposomes and the vehicle affected the rate and amount of the released drug. The cream base exhibited the slowest release, followed by the hydrogel and DMS base. Similar release profiles were achieved with both types of elastic vesicles (deformable and propylene glycol liposomes); the slowest release was observed for conventional liposomes, regardless of the vehicle used. The drug release profiles from different liposomes-in-vehicle formulations were in agreement with the physicochemical properties of the formulations. All of the liposomes were found to be compatible with the hydrogel preserving its original textures, whereas a significant decrease in all texture parameters was observed for liposomes-in-DMS base, regardless of liposome type.

Conclusion: Propylene glycol liposomes-in-hydrogel is considered as the optimal formulation for improving skin delivery of hydrophilic drug. Further investigations involving in vivo animal studies are necessary to confirm its applicability in skin therapy.