Selection of suitable suspending agent for preparation of liquid oral dosage form using ion-exchange resin

The goal of this study was the selection of a suitable suspending agent to prepare a stable oral suspension for drug delivery by ion-exchange resins. Suspending agents are used to increase the viscosity of the media to maintain uniform dispersion during storage. To select the best suspending agent، some formulations with different concentration of HEC، xanthan gum and HPMC were prepared and evaluated for physicochemical characteristics such as sedimentation volume and redispersibility. Prepared suspensions by HEC and HPMC as suspending agents in low concentrations had low sedimentation volumes and increasing in concentration caused to enhance in sedimentation volume but the redispersibility was difficult. The prepared suspensions using xanthan gum have good sedimentation volume and redispersibility. In suspensions prepared by HPMC and HEC، enhancement in concentration caused to increase in viscosity and to be difficult redispersibility that is in according to stock''s law which the more viscosity the lower sedimentation rate. Prepared formulation using xanthan gum contrast with low concentrations، in high concentrations had good sedimentation volumes and ease of redispersibility due to form a flocculating system.