Study of the binding properties of hydroxypropyl guar and its utilization in the formulation and evaluation of metoprolol tartarate tablets

Derivatization of guar to hydroxypropyl guar enhances the interaction coeffi cient and checks the hydration rate of the polymer molecule. Hydroxypropyl guar is investigated for its binding property along with sodium carboxymethylcellulose (1% w/w) as the parallel binding agent. Tablets of metoprolol tartarate were prepared by wet granulation. Pre-compression parameters such as rate of fl ow, angle of repose, Carr’s index, Hausner’s ratio, residual moisture content and assay determinations were carried out. Hydroxypropyl guar bound granules revealed lower Carr’s index value and Hausner’s ratio in comparison to sodium carboxymethylcellulose bound granules thereby indicating better free fl owing properties. In respect to post compression parameters, tablets made with hydroxypropyl guar displayed superior hardness, lesser deviation of tablet weight about the mean, a higher value of (Crushing strength: Friability)/Disintegration time, a faster drug dissolution in comparison to sodium carboxymethylcellulose bound tablets. While guar with its high intrinsic viscosity restricts its use as a retardant component in matrix tablets, hydroxypropyl guar with its enhanced interaction coeffi cient and controlled hydration rate has yielded a promising adjuvant for binding metoprolol tartarate tablets with improved in vitro performance.