Design and Evaluation of Matrix Tablets of Ambroxol Hydrochloride using Guargum

The objective of the study was to develop guargum matrix tablets for oral controlled release of Ambroxol hydrochloride. Matrix tablets of Ambroxol hydrochloride, using various viscosity grades of guar gum in three proportions, were prepared by wet granulation method. The granules were evaluated for angle of repose, bulk density, compressibility index, total porosity and drug content. The tablets were subjected to thickness, weight variation test, drug content, hardness, friability and in vitro release studies. The granules showed satisfactory flow properties, compressibility and drug content. All the tablet formulations showed acceptable pharmacotechnical properties and complied with in-house specifications for tested parameters. According to the theoretical release profile calculation, a twice daily sustainedrelease formulation should release 19.6 mg of ambroxol hydrochloride in 1 hour like conventional tablets, and 5.2 mg per hour upto 12 hours. Ambroxol hydrochloride matrix tablets containing either 30%wt/wt of low viscosity (F-III), 25% wt/wt medium viscosity (F-VI) or 20%wt/wt high viscosity (F-IX) guar gum showed sustained release. The results of dissolution studies indicated that formulation F-IX is the most successful formulation of the study and exhibited satisfactory drug release in the initial hours and the total release pattern was very close to the theoretical release profile as well as marketed sustained release ambroxol hydrochloride tablets. Applying exponential equation, the selected formulations F-III and F-VI showed diffusion-dominated drug release and followed first order kinetics.The mechanism of drug release from F-IX was diffusion coupled with erosion. Guar gum matrix tablets F-IX showed no change in physical appearance, drug content, or in dissolution pattern after storage at 40°C/relative humidity 75% for 6 months.