The Effect of Electrolyte Concentration and Polymer Content on the Rheological Behavior of Magnesium Hydroxide Suspension

Aims: Magnesium hydroxide (Mg (OH)2) is an alkaline compound that is used as an anti-acid and laxative agent. The objective of the study was to find the effect of electrolyte concentration and polymers on the rheological behavior of Mg (OH)2 suspension.
Place and Duration of Study: Department of Pharmaceutics, Faculty of Pharmacy and Nanotechnology Research Center Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
Methodology: To evaluate the effect of structural vehicle, some suspending agents such as carboxymethyl cellulose (CMC), polyvinyl pyrrolidone (PVP), tragacanth and magnesium aluminum silicate (Veegum) alone or in combination were utilized. NaCl (0.01 and 0.05 wt/vol %) was employed as flocculating agents. Physical stability parameters such as sedimentation volume, and the ease of redispersion of the suspensions were evaluated. After incorporation of structural vehicles, the rheological properties of formulations were also studied to find out their rheological behavior.
Results: The results showed that the combination of suspending agents had the most physical stability and pseudoplastic behavior with some degree of thixotropy. NaCl as flocculating agent (0.01 wt/vol %) in formulations containing tragacanth and CMC improved the rheological behavior of suspensions and sedimentation volume, while the presence of PVP could not affect these properties.
Conclusion: The results showed that viscosity and thixotropy measurement are a reliable factor to study suspension stability.