Formulation and In-Vitro Evaluation of Controlled Release Matrix Tablets of Diltiazem Hydrochloride Using Different Rate Controlling Polymers

In present study, directly compressed controlled released matrix tablets of Diltiazem Hydrochloride were formulated at drug-to-polymer ratios (D: P) of 10:1, 10:2, 10:3 using polymers Ethocel 45 Premium, K100 LV Methocel, K15M EP Premium Methocel as rate controlling agents. In some formulations of Diltiazem hydrochloride and Ethocel 45 Premium matrices, 30% of filler was replaced by Co-excipient like HPMC, CMC-Na and Starch. The in vitro dissolution studies were performed according to USP Method-I (rotating basket method). Phosphate buffer (pH 7.4) was used as dissolution medium and the rotation speed of baskets were kept constant at 100rpm and temperature of the medium was maintained at 37 ± 0.1°C. In order to determine the drug release kinetics various models such as Ist-order, Zero-order, Hixon Crowell, Highuchi and Power Law were applied. Herbesser tablets were used as reference standard for comparison of dissolution profiles of standard and tests formulation by applying difference factor (f1) and similarity factor (f2). The rate controlling agents extended the drug release rates but Ethocel 45 Premium extended more efficiently than the K100 LV Methocel and K15M EP Premium Methocel containing matrices. These newly prepared formulations released the drug mostly by anomalous non Fickian drug diffusion. The drug release profiles of the test formulations were different from the drug release profile of reference standard formulation (Herbesser tablets). The Co-excipients increased the drug released from the matrices containing Ethocel 45 premiums. Ethocel 45 Premium, K100 LV Methocel and K15M EP Premium Methocel can be effectively used as rate controlling agents in formulation of directly controlled release matrix tablets.