A comparative study of gellan gum and xanthan gum versus commercial vehicles as pharmaceutical thickening agents in oral suspensions

Pharmaceutical oral suspensions are the main form used for patients with dysphagia. Compounding these forms is challenging because they are thermodynamically unstable but must remain physically stable. Ready-to-use vehicles such as Inorpha® or Orablend® exist but these are not optimal, and physical stability can be improved using a thickening or suspending agent. High-acyl gellan gum is a European food additive (E418), also used in pharmaceutical preparations, as a gelling agent, stabilizer or thickener but never as a suspending agent. This study aimed to investigate and characterize the properties of high-acyl gellan gum as a suspending agent and to compare it with ready-to-use vehicles and with another suspending agent, xanthan gum. Rheological behaviour, sedimentation and resuspension of vehicles were studied with and without irbesartan used as a model insoluble drug. Viscosity stability was studied for 90 days at room temperature and controlled temperature. We show that the high-acyl gellan gum vehicle offers the best viscosity and stability results for use in pharmaceutical suspensions because it exhibits stable homogeneity and viscosity in time, regardless of storage temperature, and is compatible with safe administration in dysphagic patients after 90 days. High-acyl gellan gum appears to be a good suspending agent for pharmaceutical suspensions.