Preparation and in vitro characterization of diltiazem hydrochloride loaded alginate microspheres.

The main objective of the present study was to improve bioavailability of diltiazem hydrochloride and decrease the frequency of dosage form administration by increasing the encapsulation efficiency of the drug, residence time of the dosage form at the site of absorption and sustained release of the drug from the delivery system. Alginate microspheres containing diltiazem hydrochloride were prepared by the emulsification-internal gelation method by using barium carbonate as a cross-linking agent with improved encapsulation efficiency. The effect of various factors (concentration of alginate and barium chloride) on the drug loading efficiency and in vitro release were investigated. Fourier transform infrared spectroscopy (FT-IR) analysis confirmed the absence of any drug polymer interaction. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) pattern showed that the crystallinity of the drug was decreased in the dosage forms. The in vitro drug release mechanism was non-Fickian type controlled by swelling and relaxation of polymer. The stability studies of drug-loaded microspheres showed that the drug was stable at different storage conditions.