Investigation of Modified Rice Starch for Sustained Release Dosage Form

Abstract

The aim of this study was to modify the rice starch to prolong the release of drug in gastric fluid and intestinal fluid. Various types of Vietnamese rice were introduced in the study as the matrix of sustained release dosage form. Rice was thermally modified in water for a determined time at different temperatures. The rice starch was first ground and sieved. Then the powder was physically modified by heat and finally dried. The modified rice starch appeared as an odorless fine white powder. The tablet containing modified rice starch and isradipine were prepared by solid dispersion method. Scanning electron microscopy (SEM) was used to determine differences between rice starch granules within native and modified rice starch. The flow properties of modified rice starch was analyzed by Hausner ratio and Carr’s indices .The dissolution rate of tablets was evaluated in simulated gastric fluid without pepsin (buffer pH 1.2) and simulated intestinal fluid (buffer pH 6.8) at 37 ± 0.5°C. HPLC method was used to determine the amount of drug release. Swelling and erosion studies of tablets were carried out in various media. The matrix tablet containing thermally modified starch showed sustained release as compared to the control. Moreover release studies showed that the swelling and erosion of matrices influenced the drug release. The thermally modified starch could be a novel pharmaceutical excipient for sustained release dosage form design. Keywords: modified rice starch, isradipine, sustained release.