ABSTRACT:
Glyceryl monostearate and Stearic acid are waxy materials can be used in formulation of sustained release dosage form of water soluble drugs. It was decided to study the effect of these waxes at different drug: wax ratios, on the release profile of drug from matrix formulations prepared using Glyceryl monostearate, Stearic acid and both waxes in combination. Because of the high frequency of administration and short biological half-life, Verapamil HCl was considered as an ideal drug for designing sustained release formulation. The sustained release matrices of Verapamil HCl were prepared by melt granulation technique in different drug: wax ratios. Drug release was studied by using USP apparatus-I with pH 1.2 for one hour and pH 6.8 for seven hours. The drug release profile compared with marketed formulation and specifications given in USP for extended release Verapamil HCl tablets. During dissolution study different parameters such as effect of different drug: wax ratio and combination of waxes and effect of release enhancers such as MCC and Lactose were studied. The results of dissolution study showed that release of drug from matrices prepared from combination of both waxes gets more retarded than from Glyceryl monostearate and Stearic acid alone. Also study revealed that as concentration of waxes increases, release of drug from matrices decreases. Effect of release enhancers showed that use of lactose produces a higher release of drug compared to MCC. Dissolution of Verapamil HCl from matrices followed first order and Higuchi’s square root kinetic model.