A novel transdermal fomulation of 18β-glycyrrhetic acid with lysine for improving bioavailability and efficacy.

The aim of this study was to develop a novel topical liposomal system entrapping 18β-glycyrrhetic acid (GA) for the treatment of chronic allergic dermatitis. A novel liposomal system with molar ratios of GA to lysine from 1:1 to 1:3 was prepared by high-pressure homogenization. The liposomes at the optimized molar ratio of GA to lysine of 1:2 significantly improved GA loading (1.2%) and penetration in vitro. Liposomal gels containing GA 0.3, 0.6 and 0.9% were prepared to investigate the dosage effect on transdermal delivery and anti-inflammatory activity. In vivo pharmacokinetic studies were carried out by nonocclusive application of GA liposomal gels to ICR mouse ears. GA concentrations in skin and plasma increased proportionally with dose over the dose range of 0.3-0.9%. A 2,4-dinitrofluorobenzene-induced contact dermatitis mouse model was made up to evaluate the pharmacodynamics of GA liposomal gels. The liposomal gel with GA 0.9% showed a stronger anti-inflammatory activity than triamcinolone acetonide and econazole nitrate cream, while few side effects were observed in the present model. The topical administration of gel containing novel elastic liposomes of GA was safe and effective in the treatment of chronic allergic dermatitis.