Intraocular fate of dexamethasone disodium phosphate topically applied to the eyes of rabbits

After instillation of ³H-dexamethasone into the eyes of a rabbit, ³H-9α-fluoro-11β-hydroxy-16α-methyl-1,4-androstadiene-3,17-dione was found in the aqueous humor. The same metabolite was also formed by incubating ³H-dexamethasone with the anterior ocular tissues of rabbit. Identification of ³H-9α-fluoro-11β-hydroxy-16α-methyl-1, 4-androstadiene-3, 17-dione was performed by its mobility on a thin layer plate and by proving its radiochemical homogeneity after recrystailization with the unlabeled sample which had been synthesized from dexamethasone by oxidation with sodium bismuthate.When dexamethasone disodium phosphate was instilled into rabbit's eyes, it was hydrolyzed to free dexamethasone and then metabolized to 9α-fluro-11β-hydroxy-16α-methyl-1, 4-androstadiene-3,17-dione.