Evaluation of the suspending properties of Parkia biglobosa mucilage in a metronidazole suspension formulation

Abstract

Objectives: The aim of this work is to assess the suitability of Parkia biglobosa mucilage (PBM) as a suspending agent in metronidazole suspension. Methods and Materials: Metronidazole suspension was formulated with mucilage (0.1%, 0.5%, 1%, and 2% w/v) from P. biglobosa seeds as the suspending agent. Similar suspensions of metronidazole that contained (0.1%, 0.5%, 1%, and 2% w/v) tragacanth or gelatin were also prepared for comparison to PBM-based formulations. The suspensions were assessed for rheological properties, sedimentation volume, degree of flocculation, ease of redispersion, flow rate (flowability), and drug-excipient compatibility using Fourier-transform infrared spectroscopy. Results: Brownish metronidazole suspensions with a smooth and elegant appearance were obtained. After 2 weeks of storage at ambient temperature (28 ± 2°C), the ease of redispersion was in the following order: tragacanth < PBM < gelatin-containing formulations. The optimal pH of the formulation was slightly acidic and did not significantly change (p > 0.05) after 3 months of storage at ambient temperature (28 ± 2°C). However, the viscosity of the formulations was reduced by more than 30%, and the flow rate was significantly increased (P < 0.05). Suspensions formulated with 2% PBM were well-flocculated and easily redispersible. Furthermore, the sedimentation volume and sedimentation rate of suspensions formulated with 2% PBM were comparable to that of tragacanth- and gelatin-containing suspensions. Conclusion: PBM hence has great promise as a suspending agent for pharmaceutical preparations.