Preparation and evaluation of liposomes of brimonidine tartrate as an ocular drug delivery system

Abstract

Liposomes of brimonidine tartrate were prepared by film hydration method. The prepared vesicles were evaluated for photomicroscopic characteristics, entrapment efficiency, in vitro, ex- in vitro drug release, in vivo intraocular pressure lowering activity. Method employed for preparation of vesicles was found to be simple and reproducible, produced vesicles of acceptable shape and size with unimodal frequency distribution pattern. The size of sonicated liposomes was found to be approximately 210 nm and drug loading was approximately 30- 40%. The in vitro, ex- in vitro drug release studies showed that there was a slow and prolonged release of drug which followed zero order kinetics. The intra ocular pressure lowering activity of prepared formulations were determined and compared with pure drug solution. It was found that intraocular pressure lowering action was sustained for longer period of time than the pure drug solution. Stability studies data revealed that the formulations were found to be stable when stored at refrigerator temperature (2 °C to 8 °C) with no change in shape and drug content. Results of the study indicated that it is possible to develop a safe and physiological effective topical liposomal formulation which is patient compliance.