Development and investigation of Niosomes of Brimonidine tartrate and Timolol maleate for the treatment of glaucoma

Due to the drawback of conventional therapy for ocu lar delivery like poor bioavailability of drugs due to tear production, non productive absorption, transient residence time, impermeability of corneal epithelium. These problems can be minimized by the application of niosomal vesicular system as well as combination of drugs provides the additive effect o n reduction of IOP. The aim of the present study wa s to develop niosomal combination formulation of timolol maleate and brimonidine tartrate for the treatment of glaucoma. Niosomal formulations of brimonidine tart r te and timolol maleate were prepared by film hydr ation method. Span 60 and cholesterol used as an excipien t. White rabbits of both sexes, weighing between 2 to 3 kg were used for the study . The prepared vesicles were evaluated for photomicro scopic characteristics, entrapment efficiency, in vitro, exin vitro drug release, in vivo intra ocular pressure lowering activity. Methods em ployed for the preparation of vesicles were found to be si mple and reproducible, produced vesicles of accepta ble shape and size with unimodal frequency distribution patte rn. The in vitro, ex-in vitro drug release studies showed that there was a slow and prolonged release of drug whic h followed zero order kinetics. The intra ocular pr essure lowering activity of prepared formulations were det ermined and compared with pure drug solution. It wa s found that intra ocular pressure lowering action was sust ained for longer period of time which provides addi tive effect with combination. Stability study data revealed tha t the formulations were found to be stable when sto red at refrigerator temperature (2 °C to 8 °C) and at 25 ° C with no change in shape and drug content. Results of the study indicated that it is possible to develop a sa fe and physiological effective topical niosomal for mulation which is patient compliance. IOP lowering activity of the combination of timolol maleate and brimonidi e tartrate in niosomes was better as compared to alon e medication, which shows the additive effect of combination medication.