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T. Tajika, M. Kimura, T. Kida, H. Sakaki, A. Ohtori; Ocular Distribution and Metabolism After Instillation of Difluprednate Ophthalmic Emulsion in Rabbits. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2654.
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To evaluate the pharmacokinetics of difluprednate (DFBA) ophthalmic emulsion after instillation to the rabbit eyes.
DFBA ophthalmic emulsion 0.05% was single instilled to both eyes of albino rabbits at a dose of 25 µg/ 50 µL/ eye. Concentrations of DFBA and its metabolite, deacetylated difluprednate (DFB), in the ocular tissues and blood were measured at 0.25, 0.5, 1, 2, 4, 8 h after instillation using HPLC method. 3H-DFBA ophthalmic emulsion 0.05% was instilled to the right eye of pigmented rabbits single or repeated (QID for 3 days or 7 days) at a dose of 25 µg/ 50 µL/ eye/ time. The radioactivities in the ocular tissues, the autoradiography of eyeball and the radioactivities in the urine and feces were examined.
DFBA concentrations in the ocular tissues (except 4 samples of cornea) were less than the quantitation limit at any collection time. Cmaxof DFB in the cornea, iris/ciliary body and aqueous humor were 2198.78±861.81 ng/g, 277.52±32.86 ng/g, and 39.09±31.66 ng/mL and Tmax were at 0.25 h, 0.5 h and 1 h, respectively. At single instillation of 3H-DFBA, the tissue showing the highest Cmax was the cornea, followed by the iris/ciliary body, conjunctiva, anterior retina/choroids, sclera, and aqueous humor. The radioactivity concentration in the untreated eye was low. The results of autoradiograph of eyeball were supported the radioactivity concentration data. The total radioactivity excreted in the urine and feces was 99.5% of the dose up to 168 h after single instillation. At 24 h after 1st, 12th and 28th instillation of 3H-DFBA, the radioactivity concentrations in all tissues did not increase remarkably with the increase in number of doses.
Radioactivity in rabbit tissue after instillation of 3H-DFBA ophthalmic emulsion was distributed at anterior segment of the treated eye and did not appear to remain for a long period. DFBA in the ocular tissues after instillation of difluprednate ophthalmic emulsion was not detected. DFB, an active metabolite, was observed in cornea, iris/ciliary body, conjunctiva and aqueous humor.
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