Abstract:
Liposomes are well known to alter the biodistribution of entrapped substances by protecting the enclosed material. They are widely used as vehicles to target the specific molecule to specific organ especially in conditions of viral infections. A development of system which controls the release and enhances the bioavailability of Acyclovir an antiviral agent with low oral bioavailability (10-30%) is in demand. Thus present work is focused on design and development of acyclovir liposomes by reverse phase evaporation method using various ratios of phosphatidyl choline with cholesterol and Cephalin (phosphatidyl ethanolamine) with cholesterol. Based on evaluation of entrapment efficiency, the best formulations were subjected to physicochemical studies i.e., photo microscopy, in vitro drug release and stability studies. The % entrapped drug in soya lecithin liposomes of batch F17 and F21 are 60.51 and 59.69 and cephalin liposomes of F41 and F45 are 58.23 and 57.38 respectively. The formulations F17, F21, F41 and F45 sustained the release and at the end of 12 hr the % drug release was 73.89, 79.48, 76.78 and 79.77 % respectively. Short-term stability studies were carried out for the selected formulations (F17, F21, F41 and F45) for a period of two months at 4°C, 25±2°C/ 60±5% RH and 30±2°C/ 65±5% RH.  The liposomes stored at 4°C were found to be stable for duration of two months compared to other storage conditions. Hence it can be concluded that four formulations can be used for controlled release of acyclovir.

Keywords: Liposomes, Acyclovir, Phosphatidyl Choline, Cholesterol, Cephalin, Reverse Phase Evaporation.