Preparation and evaluation of lactic acid liposomes

Abstract

In this study lactic acid, a hygroscopic alpha-hydroxy acid which is used topically for increasing skin moisture content and stimulating skin cell renewal, was encapsulated within liposomes to sustain action ad decrease skin irritation, Lactic acid liposomes were prepared from egg yolk lecithin by reverse phase evaporation method. The prepared vesicles of lactic acid were LUVs in the size range of 100-500 nm. The percentage of lactic acid entrapment increased when phospholipids concentration was increased, However, the encapsulation efficiency of lactic acid expressed as moles of lactic acid per mole of lipid did not differ. An increase in lactic acid concentration increased the encapsulation efficiency of lactic acid, which reached a limit at some point where lactic acid concentration was between 80- (µ =0.5) Liposomal charge, pH, and ionic strength had interaction effects on encapsulation efficiency (p<0.05). The positively charged liposomes at pH 4 (µ =0.1) gave the highest encapsulation efficiency which was similar to that of the neutral liposomes at pH 5(µ =0.5) Inclusion of cholesterol in both positive and neutral liosomes encapsulation efficiency. Lactic acid in positively charged liposomes was released faster than that in neutral liposomes. Inclusion of cholesterol into both types of liposomes resulted in faster release. The neutral liosomes retained lactic acid better than the positively charged liposomes when stored in refrigerator for one week. Leakage of lactic acid from neutral liosomes with cholesterol a-tocopherol was negligible.