Journal d'ophtalmologie clinique et expérimentale
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In vitro and In vivo Evaluation of Timolol Maleate Ocular Inserts Using Different Polymers

Mohamed Ali Attia Shafie and Mai Ahmed Hassan Rady

The present work focuses on treatment of glaucoma by formulating ocular inserts of different polymeric combination and Timolol maleate to enhance therapeutic effect through prolonging contact time with corneal surface, accurate, and sustain the release of the drug over a long period. The selected polymers for formulation of ocular inserts are Methyl Cellulose (MC), Hydroxypropyl cellulose (HPC), Eudragit RL100 (ERL100), Eudragit RS100 (ERS100), Ethylcellulose (EC), Polyvinylpyrrolidone (PVP). Films were plasticized using different plasticizers. The prepared ocular inserts were evaluated for their mechanical properties and physico-chemical properties. Accelerated stability studies were conducted to investigate the change in appearance, pH, and drug content after storage in drastic conditions. In vitro drug release and kinetics of drug release from different formulations were studied. In vitro permeation study was conducted on selected formulations showed better results in previous studies. In vivo release study was conducted on rabbits after sterilization of ocular inserts by gamma radiation. Intraocular pressure was measured at different time intervals using Schotz tonometer. The In vitro release data of Timolol maleate from the prepared formulations followed diffusion mechanism. The permeability studies data revealed that the permeability coefficient was found to be dependent on polymer type, the higher the solubility of the polymer the higher permeability coefficient. The reduction in IOP for F3 (HPC/ERL100 5:1), F7 (MC/ERL100 1:1), and F8 (MC/ERL100 1:3) was prolonged for 120 hours (5 days), and 96 hours (4 days) for F12 (HPC/EC 15:1).