Formulation and in-vitro bioequivalence evaluation of verapamil hydrochloride matrix tablets with Calan R

The purpose of the current work was to formulate Verapamil Hydrochloride (VH) sustained release matrix tablets by using natural polymers and comparison with leading national brand Calan SR of Searle Pharmaceuticals. Tragacanth and pectin were used in various concentrations. Pre compression studies i.e. angle of repose, bulk density, tapped density, Carr’s compressibility index and Hausner’s ratio were also performed and found within the Pharmacopoeial limits. Eight formulations (F1-F8) of (VH) were prepared by direct compression method. Post compression studies i.e. Thickness, Hardness, Diameter, Friability and Dissolution studies were conducted. Different kinetic models i.e. zero order, first order, Highuchi model and Korsmeyer Peppas were applied to study release patterns and similarity index was calculated. Dissolution studies were carried out in phosphate buffer of pH 6.8 showed that formulations (F4 and F8) formulated with higher polymers concentration showed comparatively better drug retardation. F5 was the most comparable with the reference product. Verapamil hydrochloride released was observed non-fickian as diffusion following Higuchi model.