Formulation and evaluation of floating matrix tablets of diltiazem hydrochloride

Abstract

This study was performed to design floating tablets of diltiazem as a model drug for prolongation of gastric residence time. A simple visible spectrophotometric method was employed for the estimation of diltiazem at 236 nm and Beer’s law is obeyed in the concentration range of 2-20 mg/ml. Preformulation studies were carried out to optimize the ratios required for various grades of HPMC-SCMC and HPMC- Carbopol P934. Total 10 formulations (five each) were prepared using HPMC (K4M). The prepared floating tablets were evaluated for hardness, weight variation, thickness, friability, drug content uniformity, buoyancy lag time, total floating time, water uptake (swelling index), and in vitro dissolution studies. SEM and stability studies were carried out only for best release formulations (A1 and B1). Among the five formulations with HPMC K4M and A1-A4 showed drug release ranging from 99.89 to 77.52%. Similarly five formulations with HPMC K4M and Carbopol P934 (B1-B4) showed drug release ranging from 97.9 to 80.35% in 0.1 N HCl dissolution medium.Formulations A1 and B1 gave maximum drug release upto 100% within 12 hrs. SEM for A1 and B1 formulations revealed that surface was smooth upto 4 hrs after that swelling and porosity of tablet increased indicating the diffusion and erosion mechanism of release.