In vitro release kinetics study of diltiazem hydrochloride from wax and Kollidon SR based matrix tablets

Extended-release matrix tablets of diltiazem hydrochloride (DTZ) were prepared using waxy materials alone or in combination with Kollidon SR. Matrix waxy materials were carnauba wax (CW), bees wax (BW), cetyl alcohol (CA) and glyceryl monostearate (GMS). Dissolution studies were carried out by using a six stations USP XXII type 1 apparatus. The in vitro drug release study was done in 1000 ml phosphate buffer of pH 6.8 for 12 h. Initial burst release was observed in case of waxy granules. Tablets prepared in combination of waxy granules and Kollidon SR sustained the drug release for more than 12 h. Addition of ludipress instead of Kollidon SR caused the drug release faster (for less than 12 h). Fitting the in vitro drug release data to Korsmeyer equation indicates that diffusion along with erosion could be the mechanism of drug release. Significant differences were found among the drug release profile from different polymeric matrices.