DESIGN OF DOUBLE LAYER TABLETS OF VALETHAMATE BROMIDE BY USING VARIOUS POLYMERS BY DIRECT COMPRESSION METHOD

Abstract

Double layer of valethamate bromide tablets containing 10 mg initial dose and 30 mg maintaining dose in the first and second layers were designed in order to prolong drug release. Xanthan gum, sodium alginate, hydroxypropylmethyl cellulose and carbomer were used for the second matrix layer at various concentrations. Physical controls were made for characterization of tablets and their powder mixtures. Drug:excipient compatibility was investigated by Fourier Transform Infrared Spectroscopy and Differential Scanning Calorimetry. Results indicated that double layer tablets met compendial requirements in order to provide pharmaceutical quality. Drug release was observed to be faster from sodium alginate tablets followed by xanthan gum, hydroxypropylmethyl cellulose and carbomer at the same concentrations in the second layer (50%) (p0.5). The initial drug release could be obtained within 2 hours except tablets containing 50% carbomer. However, consistent drug release could not be obtained with sodium alginate tablets that released more than 80% of drug up to 3rd hour. The non-Fickian kinetics correspond to coupled diffusion/polymer relaxation that was clear with HPMC and carbomer tablets. Polymer relaxation resulted in tablet erosion was faster for tablets containing xanthan gum. Swelling and erosion study on tablets were supported drug release data. Tablets containing carbomer and HPMC were observed to be suitable for prolonged drug delivery. HPMC tablets released about 75% of drug at the 8th hour when tablets containing 30% and 40% carbomer released about 65% of drug.