In vitro anti-inflammatory efficacies of liposomal suspensions of acetylsalicylic acid

Egg phosphatidylcholine (EPC) liposome containing acetylsalicylic acid (ASA) (EPC/ASA liposome) was prepared by a film hydration and sonication method, and the effect of liposome on the in vitro anti-inflammatory efficacy and the in vitro skin permeation of ASA was investigated. The mean diameter of EPC liposome and EPC/ASA liposome was about 271 and 175 nm, respectively. Both of liposomes were multi-lamellar vesicles on transmission electron microscopy photos. The in vitro viability of cell (Raw264.7) treated with EPC/ASA liposome suspension was significantly lower than the viability of cell treated with ASA solution. The amount of nitrite and prostaglandin E2 produced by cell treated with EPC/ASA liposome suspension was significantly lower than the amount produced by cells treated with ASA solution, indicating EPC liposome boosted the anti-inflammatory efficacy of ASA. The amount of ASA permeated through hairless mouse skin was inappreciable for 24 h when ASA solution was applied, whereas the permeation amount markedly increased to about 185 μg/cm² for 24 h when EPC/ASA liposome suspension was applied. EPC liposome also enhanced the permeation into stratum corneum and epidermis/dermis.