Development and In vitro Evaluation of Swellable Floating Formulation of Captopril

The purpose of the present work was to formulate and evaluate the effervescent floating tablets of captopril using blend of natural and synthetic polymers. Ten formulations of floating tablets were prepared using Psyllium husk, Hydroxypropylmethylcellulose (HPMC K100M) and sodium bicarbonate (NaHCO3) by direct compression technology. Fourier transform infra red spectrometry (FTIR) and Differential scanning calorimetry (DSC) were performed to elucidate the interaction of drug with polymer and excipients. Floating units were evaluated for physicochemical parameters like hardness, diameter, thickness, swelling index, mass uniformity, percent drug content, buoyancy lag time and drug release. Swelling and in vitro release studies were carried out in 0.1 N HCl at 37 degrees C using paddle apparatus. The formulated tablets were optimized on the basis of buoyancy time and drug release. FTIR and DSC results showed no detectable incompatibility between drug and polymers. The diameter of all formulations was found to be in the range of 9.82-10.78 mm; thickness was in the range of 3.914-4.437 mm. The hardness was calculated to be in the range of 1.92-2.75 kg/cm(2). The buoyancy time remained less than 3.5 min and duration of floating did not exceed 12 h for all formulations. The results of swelling studies showed higher percent swelling on increasing the polymer concentration. The value of 'n' was in the range of 0.409-0.755 which is indicator of drug release by fickian as well as non-fickian or anomalous diffusion mechanisms. The study concluded, C4 as the best optimized formulation for the extent of drug release was found to be around 99.24 +/- 1.26% and showed buoyancy lag time at 114 +/- 10 s with floating duration of >= 12 h.