Formulation and Evaluation of Sustained release tablets of Tizanidine

The objective of this study is to formulate and evaluate the sustained release matrix tablet of Tizanidine Hydrochloride by direct compression method. In the present study, Tizanidine is chosen as a model drug which is Muscle relaxant. Because of its short half life (2.5hrs), its water solubility and less bioavailability (40%) it was chosen as a suitable candidate for sustain matrix tablet formulation. It was formulated in to matrix tablet using polymer such as iota-Carrageenan and Polyethylene oxide as releases retardants. All the pre-compression parameters, post-compression parameters were found to be within the standard IP limits. Matrix tablet with Carrageenan and Polyethylene oxide successfully sustained the release of Tizanidine for a period of 12hrs. The concentration of tizanidine was kept constant, MCC-101 and lactose (1:3 ratio) used as filler. The maximum in-vitro release (at 50rpm, temperature 37±0.5°C, and 0.1N HCl, pH 6.8 phosphate buffers) was found to be 97.8% and 98.6% over a period of 12hrs for formulations C4 and P4. The data of in-vitro release from tablets were fitted to different kinetic models to explain the release profile. Formulations C4 and P4 were best