After adding neomycin sulfate to a water diluted Beconase aqua, a flake-like precipitation occurs.

Beconase Aqua is a suspension in which Avicel is used to increase viscosity. This type of Avicel contains 10% CMC and this negatively charged macromolecule is incompatible with neomycin (+). Given the active ingredient of Beconase is available in bulk, there is the possibility to prepare a "loco" Beconase with a non-Ionogen thickening agent such as e.g. Hydroxyethylcellulose (Natrosol mV).