PROPERTIES OF ACYCLOVIR-CONTAINING LIPOSOMES FOR POTENTIAL OCULAR DELIVERY

Loading efficiency and release characteristics of ac iclovir-containin g liposomes were investigated in this study. It was found that positiv ely charged liposomes gave the highest loading efficiency. The neutral liposomes showed a loading efficiency in between those of the positiv ely charged and negatively charged liposomes. Liposomes prepared with an acyclovir concentration of 5 mg/ml demonstrated a loading efficienc y greater than that with an acyclovir concentration of 1 mg/ml. Liposo mes prepared by the method of drug-lipid film hydration with medium pr esented a higher loading efficiency than that prepared by lipid rilm h ydration with drug solution. For all liposomes, the release rate was f aster at pH 7.4 than at pH 8.0. For positively charged liposomes, the release rate was faster at higher molar ratios of stearylamine. Howeve r, for negatively charged liposomes, the release rate with a molar rat io of dicetylphosphate at 0.15 was greater than at 0.3. Decrease of mo bility was found for positively charged liposomes after loading with a cyclovir, whereas, no significant change in mobility was observed for negatively charged and neutral liposomes. (C) 1998 Elsevier Science B. V.