Study on glycolic acid delivery by liposomes and microspheres

Glycolic acid is used in many cosmetic products as exfoliant and moisturizer. Unfortunately, the greater glycolic acid cosmetic benefits the greater is the potential for skin irritation as far as burning. The aim of this work was to investigate the feasibility of topical controlled delivery systems loading glycolic acid in order to optimize the acid cosmetic properties lowering its side effects. For this purpose different types of microparticulate systems have been evaluated: liposomes, liposomes modified by chitosan addition and chitosan microspheres. Liposomes, composed of phosphatidylcholine and cholesterol (1:1 molar ratio) and with different glycolic acid/lipid molar ratio, were prepared by reverse phase evaporation method. Two types of interaction between liposomes and chitosan were investigated: chitosan addition into lipidic bilayer during liposome preparation and coating of already formed liposomes with chitosan. Glycolic acid loaded chitosan microspheres were prepared by the dry-in-oil emulsion method. The microparticulate systems were morphologically characterized by electron microscopy and particle size analysis. In vitro dissolution tests were performed to evaluate the feasibility of microparticulate systems in modulating glycolic acid release. The results obtained show that liposomes are always suitable to modulate glycolic acid release and that the best condition to achieve this control is obtained by the liposomal systems in which glycolic acid/lipid molar ratio is 5:1. Further significant release control is obtained by addition of chitosan into the liposomes, while chitosan microspheres are not able to control glycolic acid release even after crosslinking.