HII mesophase as a drug delivery system for topical application of methyl salicylate.

The main objective of this study was to develop reversed hexagonal (HII) mesophase for transdermal delivery of methyl salicylate. The formulation was prepared, characterized and evaluated for its skin penetration in vitro and skin retention in vivo. Preliminary pharmacodynamics and skin irritation were also investigated. The formulation was identified as hexagonal structure. In vitro study exhibited that HII mesophase enhanced the skin permeation by delivering 2.61 times more methyl salicylate than the commercially available cream. Meanwhile, HII mesophase presented higher bioavailability as AUC(0-24) and AUC(0-∞) were 32.894μg·mL-1 and 32.935μg·mL-1 respectively, while the cream were 12.791μg·mL-1 and 12.970μg·mL-1. Preliminary pharmacodynamics studies demonstrated that HII mesophase possessed anti-inflammatory and analgesic effects for inhibiting paw edema, granuloma and pain. MeSa HII mesophase showed no skin irritation on the normal rat skin. Thus, HII mesophase was considered as an effective delivery system for MeSa.