Hydrophilic substances are most easily wetted by water or other polar liquids. Hydrophobic substances repel water but can generally be wetted with nonpolar liquids. Only the minimal amount of wetting agent compatible with producing an adequate dispersion should be used, as excessive amounts of surfactants may cause foaming or unacceptable taste. In most pharmacies, the method of preparation for all suspensions is the mortar and pestle. A common mistake in the compounding of suspensions is to use too much of the suspending liquid in the initial wetting step.
High shear is critical to the initial wetting step.
After thoroughly wetting the solids with minimal wetting agent, the suspension can be diluted with further portions of the vehicle. Foregoing a long, dry technical discussion, remember both situations may be mitigated by employing strategies that favor dispersion of the particles within the suspension. Basically, a flocculated suspension is the result of the formation of loose aggregates. Loose is the key word. The compounding pharmacist doesn't have this luxury of time to explore various options.