Effect of Physiochemical Properties on the Release Profile of Diltiazem HCl and Naproxen from HPMC and Kollidon SR based Matrix Tablets

The present study was undertaken to investigate the effect of Physiochemical properties on the release profile of drug from matrix systems. As the physico-chemical nature of the active ingredients influence the drug retarding ability of these polymers, two different drugs were used to evaluate their comparative release characteristics in similar matrices. Matrix tablets of Naproxen (NPR) and Diltiazem HCl (DTZ) using Hydroxypropyl Methylcellulose (HPMC-15cps) were prepared separately by direct compression process. The USP Basket method was selected to perform the dissolution test carried out in 1000 ml phosphate buffer of pH 6.8 for 8 hours. Statistically significant differences were found among the drug release profile from different classes of polymeric matrices. The release kinetics was found to be governed by the type and content of polymer in the matrix system. Higher polymeric content in the matrix decreased the release rate of drug because of increased tortuosity and decreased porosity. At lower polymeric level, the rate and extent of drug release were elevated. Release rate was also found to be the function of physico-chemical nature of drug molecule. Diltiazem HCl, being soluble in nature, released faster than Naproxen from all matrix systems. The release mechanism was explored and explained with biexponential equation. Release profile showed a tendency to follow Korsmeyer kinetics from matrix systems. The mean dissolution time (MDT) was calculated for all the formulations and the highest MDT value was obtained with Naproxen. The results generated in this study showed that the profile and kinetics of drug release were functions of polymer type, polymer level and physico-chemical nature of drug.