Original Articles: 2012 Vol: 4 Issue: 3
In vitro release kinetic study of ambroxol hydrochloride sustained release matrix tablets using hydrophilic and hydrophobic polymers
The purpose of the present investigation was to design and evaluate sustained release tablets of a sparingly water soluble drug Ambroxol Hydrochloride, employing hydrophilic and hydrophobic polymers and to select the formulation based on pharmacokinetic of Ambroxol Hydrochloride. Two hydrophilic polymers Methocel K15M CR and Methocel K100M CR and hydrophobic Eudragit RL100 were used in tablets prepared by direct compression. The granules were evaluated for angle of repose, loose bulk density, tapped bulk density, compressibility index, total porosity and drug content. The tablets were subjected to various tests for physical parameters such as thickness, hardness and friability, and in vitro release studies. The in vitro dissolution study was carried out for 12 hours; in 0.1 N hydrochloric acid (pH 1.2) for first 2hrs followed by phosphate buffer at pH 6.8 ±0.2. The results of dissolution studies indicated that formulations containing Methocel K100M CR showed better dissolution properties compared to formulations containing Methocel K15M CR. The drug release data fit well to the Higuchi expression, but a close relationship was also noted with zero order kinetics. Korsmeyer’s plot indicated that the drug release mechanism from the matrix tablet followed Fickian mechanism. It was found that Methocel K 15M CR and Methocel K100M CR matrices except one formulation followed first-order kinetics at all proportions whereas Eudragit RL100 matrices followed zero-order kinetics at higher concentration (at 40%). Hydrophilic and hydrophobic matrix tablets (F-3, F-6 and F-9) showed no change in physical appearance, drug content or dissolution pattern after storage at 40Ã¢ÂÂ°C temperature and relative humidity 75% for 6 months.