Viscosity builders (thickening agents) are substances that increase the viscosity of liquid or semisolid pharmaceutical preparations such as suspensions, syrups, and gels.
Significance
Stability and Uniform Dispersion: Increased viscosity helps suspend solids evenly (in suspensions) and prevents phase separation (in emulsions).
Patient Acceptability: Controlled viscosity can improve mouthfeel and ease of administration.
Controlled Release: In certain formulations (like gels or ointments), thickening agents can modulate the release of active ingredients.
Examples & Uses
Guar gum: Derived from guar beans, thickening agent in suspensions and emulsions.
Xanthan gum: Fermentation-based thickener, stabilizer for syrups, gels, and suspensions.
Pectin: Extracted from citrus peels or apples, used for thickening, stabilization, and controlled drug release.
Agar or Carrageenan (from seaweeds) – Used in gel formulations; common in food (e.g., “agar-agar”) but also suitable for pharmaceutical use.
