Stabilizing effect of inorganic phosphate salts on antibiotic-steroid ophthalmic preparations

Drocinonide phosphate potassium forms an insoluble complex with neomycin sulfate in aqueous solution. Dibasic sodium phosphate can be employed in an ophthalmic formulation to prevent the formation of this precipitate without affecting the stability of the steroid or the bioactivity of the antibiotic. Other phosphate steroid salts behaved in a like manner.