Emulsifying and Suspending Properties of Enterolobium cyclocarpum Gum
Background:The thermodynamic instability of emulsions and suspensions necessitate the incorporation of emulsifiers and suspending agents respectively, in order to stabilize the formulations and ensure administration of accurate doses.
Objective:Enterolobium cyclocarpum gum was characterized and evaluated for its emulsifying and suspending properties in comparison with official acacia gum.
Method:Physicochemical and phytochemical characterization of Enterolobium cyclocarpum gum (ENCG) were carried out. Emulsifying properties were assessed using creaming rate, globule-size distribution and viscosity measurements. Metronidazole suspensions containing 1.0 -5.0%w/v of ENCG (or acacia) were assessed by sedimentation volume, pH determinations, viscosity and flow rate. Primary emulsions containing ENCG (or acacia) were formulated. Polysorbate-80 was also incorporated in the formulations to enhance the surface activity of the system.
Results:ENCG contains anthraquinones, cardiac glycosides and flavonoids. It is a highly viscous, weakly acidic gum (pH 5.96 at 250C), with a high hydration power and swelling index of 15.14. Acacia emulsions were more stable than ENCG emulsions, however, polysorbate-80 at 8.95 %v/v, reduced the creaming rate of the emulsions. Globule size and viscosity (250C) ranked ENCG emulsions > acacia emulsions. Sedimentation volume decreased over time with ENCG suspensions demonstrating faster sedimentation rate. The pH of the suspensions remained relatively unchangedSuspensions containing ENGG were more viscous and the flow rates ranked ENCG suspensions < acacia emulsions.
Conclusion:The results suggest that Enterolobium cyclocarpum gum is a highly viscous, poorly emulsifying gum but it hassuspending properties comparable with official acacia gum.
Keywords: Enterolobium cyclocarpum, Emulsions, Suspensions, Pharmaceutical excipients.