Development and optimization of Diltiazem hydrochloride loaded microspheres by using different Eudragit polymers

The problems of frequent administration and variable low bioavailability (40%-60%) after an oral administration of the conventional dosage forms of Diltiazem hydrochloride can be attenuated by designing it in the form of microspheres which would prolong the residence time at the absorption site to facilitate intimate contact with the absorption surface and thereby improve and enhance the bioavailability. Microspheres of Diltiazem hydrochloride were formulated using Eudragit S 100 and Eudragit L 100 alone by solvent evaporation methods with an aim to prolong its release. Six formulations prepared by using different drug to polymer ratios were evaluated for relevant parameters. The scanning electron microscopic study indicated that the microspheres were spherical in shape and the drug remained dispersed in the polymer matrix at amorphous state. In vitro studies were carried out at different pH for a period of 12 hours. Drug polymer interaction was absent as evidenced by FT-IR.