Evaluation of the Suspending Properties of a Novel Hydrophilic Biopolymer Derived from the Tubers of Ipomoea batatas on Sulphamethoxazole Suspension

Aims: This work examines a novel hydrophilic biopolymer, I-polygel derived from Ipomoea batatas tubers (Convolvulaceae) as a suspending agent in sulphamethoxazole suspension using acacia and tragacanth respectively as comparing standards.

Methods: Aqueous suspensions of sulphamethoxazole containing 1, 2, 4 or 5% w/v of I-polygel, acacia or tragacanth respectively were prepared and evaluated using sedimentation volume, rheology, viscosity, free-thaw cycle and redispersibility tests.

Results: Sedimentation volume was proportional to the concentrations of suspending agents across the preparations with the suspensions containing I-polygel exhibiting more consistency: I-polygel > acacia > tragacanth > control (P = 0.000). The flow rates were inversely proportional to the concentrations of the respective suspending agents whereas the reverse was the case with viscosity. There was no impediment to the flow of the suspensions at the concentrations of the suspending agents employed. The suspensions containing I-polygel indicated higher viscosities in all the concentrations: I-polygel > acacia > tragacanth > control (P = 0.000). There was no significant particle size increase before and after the freeze-thaw cycle test, showing that sulphamethoxazole may be stable in the presence I-polygel, acacia and tragacanth. All the preparations containing I-polygel was redispersed with the minimal shear stress: I-polygel < acacia < tragacanth < control (P = 0.000).

Conclusion: The application of a newly developed hydrophilic polymer, I-polygel as a suspending agent in comparison to acacia and tragacanth in the formulation of sulphamethoxazole suspensions yielded a more consistent and stable suspension with statistically proven higher sedimentation volume, better rheological properties, higher viscosities and ease of redispersion of suspension with minimal shear stress.