NON-IONIC SURFACTANT VESICLES (NIOSOMES) BASED NOVEL OPHTHALMIC FORMULATION OF TIMOLOL MALEATE

Abstract

The objective of the present work was to develop drug loaded niosomal ophthalmic formulation of timolol maleate (an antiglaucomal drug) for enhanced trans-corneal drug permeation and better ocular bioavailability. Timolol loaded niosomes were prepared by thin film hydration method using rotary evapoarator and ultra-sonicated for size reducation using probe sonicator. The nano-vesicle (niosomal) formulation was optimized by selecting surfactant content, cholesterol content and sonication time as independent variables and particle (vesicle) size, drug entrapment efficiency and % drug release as response variables for optimization studies. The timolol maleate niosomal (TMN) formulation was evaluated for particle size, pH and osmolality  and was found to possess the desired properties. The developed TMN formulation was studied for % cumulative in-vitro drug release using bottle rotating apparatus (electrolab) and was found to be 79.98% over 8 hr period exhibiting sustained drug release profile. The ex-vivo trans-corneal drug permeation profile of developed TMN was studied using modified franz-diffusion cell apparatus (Permegear) and the % cumulative drug permeation across freshly excised goat cornea was found to be 65.90 % in 8 hrs duration, which was approximately 1.5 times higher than the conventional eye drop formulation. The developed TMN was also proved to be isotonic and non-irritant in HET-CAM ocular irritancy test. It was therefore, concluded from above studies, that the developed timolol maleate niosomal (TMN) formulation is better than conventional eye drops due to longer corneal retention, sustained drug release and better trans-corneal drug permeation and thereby higher ocular bioavailability, hence, would need less frequent administration.