Comparative study of drug release behaviour of Diltiazem Hydrochloride using Guar gum and HPMC as a polymer

The present study aimed to formulate and evaluate of Diltiazem Hydrochloride using guar gum and hydroxypropyl methylcellulose (HPMC) as release-retarding polymers for controlled drug delivery. The pellets were prepared by a layering technique, where guar gum was applied onto drug-loaded pellets using a suitable binder, followed by coating with HPMC in selected formulations. Preformulation studies, including drug–excipient compatibility using FTIR spectroscopy, confirmed the absence of any significant interaction, indicating the stability of the drug within the formulation. Dissolution studies were carried out using USP Type II apparatus in phosphate buffer (pH 7.2) for a period of 8 hours. The results demonstrated that drug release was significantly influenced by the type and concentration of polymer used. Formulations containing guar gum exhibited relatively faster drug release due to rapid swelling and erosion, whereas HPMC-coated pellets showed a more controlled and sustained release profile owing to the formation of a strong gel barrier. Increasing polymer concentration multiparticulate pellets in both cases resulted in a decrease in drug release rate. Among all formulations, the 1:1 drug-to-polymer ratio exhibited a uniform and desirable release pattern. Comparative evaluation indicated that HPMC was more effective than guar gum in sustaining drug release. Overall, the study concludes that multiparticulate systems using appropriate polymer combinations can successfully modulate drug release and improve therapeutic efficacy.