IOPIDINEŽ 0.5% Ophthalmic Solution contains apraclonidine hydrochloride, an alpha adrenergic agonist, in a sterile isotonic solution for topical application to the eye. Apraclonidine hydrochloride is a white to off-white powder and is highly soluble in water. Its chemical name is 2-[(4-amino-2,6 dichlorophenyl) imino]imidazolidine monohydrochloride with an empirical formula of C9H11Cl3N4 and a molecular weight of 281.57. The chemical structure of apraclonidine hydrochloride is: