Development of Thermosensitive Ophthalmic in situ Gels of Bimatoprost for Glaucoma Therapy

Background: In recent years, ophthalmic in situ gels have gained wide importance for the sustained delivery of drugs into the eye by overcoming the demerits of conventional eye drops. Objectives: The present investigation was undertaken to formulate and evaluate Bimatoprost loaded thermosensitive ophthalmic in situ gels for providing prolonged drug release pattern with good patient acceptance. Methods: Bimatoprost thermosensitive ophthalmic in situ gels were prepared by the cold method using temperature dependent polymers, Poloxamer 188/poloxamer 407 in combination with HPMC K4M as viscosifier used in three different concentrations. The prepared in situ gels were evaluated for appearance, clarity, pH, gelling capacity, gelation temperature, drug content and drug release study. The optimized batch of the formulation was subjected to drug release kinetics, ex vivo drug permeation, sterility, isotonicity, in vitro ocular irritancy test and short-term stability studies for 3 months. Results: From the drug release study, it was found that formulation; BT-5 had the highest drug release with higuchi release kinetic mechanism. The formulation (BT-5) was found to be sterile and the HET- CAM test confirmed that there was no ocular irritation and the formulation was stable for a period of 3 months without any significant changes in the evaluation parameters. Conclusion: Bimatoprost thermosensitive ophthalmic in situ gels can be a better alternative approach to provide sustained delivery of the drug by reducing the frequent drug instillation for the treatment of glaucoma.