ABSTRACT:
The present study was undertaken to find out the potential of Xanthan gum to act as a release retardant in tablet formulations and the effect of calcium sulphate dihydrate (water insoluble) or lactose (water soluble) as diluent on the release of Diltiazem hydrochloride was studied. Tablets were prepared by wet granulation method containing calcium sulphate dihydrate as excipient, diltiazem hydrochloride as model drug using 10%, 20% and 30% of gum as release retardant, magnesium stearate was used as lubricant. Similarly tablets were prepared replacing lactose with calcium sulphate dihydrate. Physical and technological properties of granules and tablets like flow rate, carr index, hausner’s ratio, angle of repose, hardness, friability and disintegration time were determined and found to be satisfactory. The drug release increased with decreased proportion of the gum irrespective of the solubility characteristics of the excipient. The values of release exponent ‘n’ are between 0.37 and 0.54. This implies that the release mechanism is Fickian. The t50% values for tablets containing calcium sulphate dihydrate were on an average 10%-15% longer than the tablets containing lactose as excipient. These relatively small differences in t50% values suggest that the nature of excipient used appeared to play a minor role in regulating the release, while the gum content was a major factor.