RESUMO
OBJECTIVE: To prepare berberine hydrochloride liposomes and investigate the influence of different factors on the entrapment efficiency. METHODS: Berberine hydrochloride liposomes were prepared by a novel pH gradient method. The transmembrane gradient was set up by ion exchange resin. UV-visible spectrophotometry and laser particle analyzer were applied to determine the entrapment efficiency and the size of berberine hydrochloride liposomes, respectively. The influences of various factors, including exterior pH values, the basic solutions of external water phase, phospholipids, incubation temperature and time, adding sequence and the ratio of drug to lipid, on the entrapment efficiency were investigated. RESULTS: Entrapment efficiency increaced with higher pH values, the best basic solution is phosphate buffer and HSPC is the most suitable phospholipid, the entrapment efficiency was enhanced by increacing incubation temperature and time, not affected by adding sequence, and the optimal ratio of drug to lipid was 1: 10. The entrapment efficiency of berberine hydrochloride liposomes under the optimum conditions was (98.6 ± 0.68)% (n = 3), and the mean diameter was 124.1 nm. CONCLUSION: The berberine hydrochloride liposomes with high entrapment efficiency are prepared by a novel pH gradient method, and the method is proved to be feasible. Copyright 2013 by the Chinese Pharmaceutical Association.