Pirenoxine which is a preparation of 1-hydroxy-5-oxo-5h-pyrido(3,2-a)-phenoxazine-3-carboxylic acid, a compound having a chemical structure similar to xanthommatin, an eye pigment of the insect, with a pyridophenoxazone nucleus.pirenoxine is found to competitively inhibit the action of the quinone substances. extensive experiments, both basic and clinical, have proven that this agent prevents the progress of cataract.indications:senile cataract, diabetic cataractdirection:dissolve a tablet in 15 ml of the solvent. a clear yellow ophthalmic solution is obtained. instil 1-2 drops of the prepared solution into the eye 5 times daily.