Development and in vitro analysis of floating matrix tablets of metronidazole using Brachystegia eurycoma gum

Floating dosage forms aim to significantly increase the gastric residence time of drugs in the gastric region for several hours. Hence, this research was carried out to formulate and evaluate floating matrix tablets (FMT) of metronidazole using Brachystegia eurycoma (BE) gum as a matrix former. Floating matrix granules (FMG) were prepared by wet granulation method using the BE gum mucilage at different concentrations (2, 4, 6 and 8% w/w). Sodium bicarbonate (30%) and tartaric acid (5%) were added as the carbon (iv) oxide generating agents. Formulations were either prepared alone with the Brachystegia eurycoma or with the addition of 1.0% w/w of Eudragit RS100. All FMG were evaluated for micromeritic properties and compressed at an optimized compression pressure of 30 arbitrary unit on the tableting machine load scale. FMT were analyzed for hardness, friability, floating lag time (FLT), in vitro buoyancy test and drug release profiles. Data from the release studies were subjected to analysis by zero order flux, first order, Higuchi square root of time relationship and Korsmeyer equations. From the results obtained, all formulated FMG were flowed freely with angle of repose and Carr's index between 15.2o to 29.1o and 10 to 18% respectively. FLT for FMT was < 820 sec. The in vitro buoyancy test of FMT formulations using the BE gum mucilage alone (i.e. without the incorporation of Eudragit RS100) were <12 h while those with Eudragit RS100 were >12 h. All FMG were compressible with tablet hardness and percentage friability between 12.4-49.1 N and 0.77-0.97% respectively. There was a significant difference in tablet hardness with increase in binder concentration (p<0.05). All formulations fitted well into Higuchi model release kinetics. Formulations BE1-BE4 have their exponent values < 0.45, hence their release mechanism was by Fickian diffusion while for BE5 the exponent value was > 0.45, therefore the release mechanism for this formulation was by non Fickian diffusion. The indication is that FMT of metronidazole have been developed using BE gum mucilage as a matrix former, this can be exploited in the formulation of controlled release systems.