Optimization and in Vitro Evaluation of 5-fluorouracil – Loaded Long – Circulating Liposomes

5-Fluorouracil (5-FU) is an anticancer drug widely used in the treatment of colorectal cancers. In this work, long-circulating liposomes (LCL) were proposed as carriers able to improve the therapy with 5-FU. The objective was to optimize the formulation of 5-FU-loaded long circulating liposomes (LCL-5-FU) using the method of experimental design and to evaluate the in vitro drug release and cytotoxicity on C26 murine colon carcinoma cells cultivated in monoculture as well as in coculture with murine peritoneal macrophages. The influence of phospholipids concentration and phospholipids to cholesterol molar ratio was studied on 5-FU liposomal concentration, entrapment efficiency and liposomes’ size. The optimized formulation (LCL-5-FU-OPT) had liposomal 5-FU concentration of 331.4 μg/mL, entrapment efficiency of 3.18 % and liposomes’ size of 200 nm. The in vitro release test has shown a diffusion of 5-FU of 90% in 3 hours. The cytotoxicity data indicated that LCL-5-FU-OPT exerted strong and similar inhibitory effects on the proliferation of C26 tumour cells under both culture conditions as those exerted by free 5-FU administration. In conclusion, the liposomal 5-FU formulation optimized within our studies might offer promise for future anti-cancer therapies based on passive tumour targeting by using LCL.