Comparative Evaluation of Metronidazole Suspensions Formulated with Raphia africana Hydrocolloid and other Natural Polymers

The suspending properties of Raphia africana hydrocolloid were assessed comparatively with some natural polymers - compound tragacanth powder, acacia gum and gelatin in metronidazole suspension formulations. The gum was extracted from the exudates of R. africana palm, and then characterized. Different batches of metronidazole suspension were prepared using the polymers at 0.5 – 4.0 %w/w concentrations. Various properties including sedimentation volume, redispersibility, viscosity, flow rate, degree of flocculation and particle size for all the polymers were evaluated comparatively. It was discovered that their suspending ability was in the order of R. africana gum > compound tragacanth > acacia > gelatin. Generally, the higher the concentration of these polymers, the higher the sedimentation volume, redispersibility number, viscosity, degree of flocculation and particle size, and vice versa for the flow rate. From statistical analysis using SPSS statistical package, R. africana gum exhibited significantly higher sedimentation volume, viscosity and flocculation (p<0.05), and lower flow rate (p<0.05) than other tested materials. The results suggest that R. africana gum has strongest and best suspending properties of all the investigated natural polymers at all employed concentrations and thus has good potential as a novel suspendant in pharmaceutical suspensions.