DESIGN AND EVALUATION OF SUSTAINED RELEASE MULTIPARTICULATE SYSTEM OF TIZANIDINE HYDROCHLORIDE

The aim of the present investigation is to formulate and evaluate Tizanidine hydrochloride sustained release pellets. Tizanidine hydrochloride is an immadazole α₂-adrenergic agonist used in the management of increase in muscle tone associated with spasticity. It has short biological half-life of 2- 2.5 hrs and is rapidly eliminated from the body. Sustained release dosage form of Tizanidine hydrochloride was developed for reduction in total amount of dose administration, to improve patient compliance, and increase efficiency in the treatment. The pellets were prepared by pan coating and fluidized bed coating technique (Wurster type) using hydroxy propyl methyl cellulose E₅ (HPMC E₅), Ethyl cellulose N-50, Eudragit L-100 as polymers and Isopropyl alcohol, Methylene dichloride as solvents. The pellets are filled in capsules and evaluated for weight variation, content uniformity, moisture content, lock length, disintegration and in-vitro dissolution tests and the results were found to be within the limits. A comparative study of dissolution profile of different batches with marketed product was performed. The optimized batch showed good similarity with the marketed product (Zanaflex Capsules). The dissolution data was fitted with various kinetic models, and the optimized formulation followed zero order kinetics by non-Fickian case-II diffusion process. Stability studies were conducted for 3 months according to ICH guidelines and found to have good results.