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-9alpha-fluoro-11beta-hydroxy-16alpha-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-9alpha-fluoro-11beta-hydroxy-16alpha-methyl-1,4-androstadiene-3,17-dione was performed by its mobility on a thin layer plate and by proving its radiochemical homogeneity after recrystallization 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 9alpha-fluro-11beta-hydroxy-16alpha-methyl-1,4-androstadiene-3,17-dione.