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S. M. Hariprasad, M. Sanders, J. Chastain, M. Curtis, R. Faulkner, D. Dahlin; Periocular Distribution of Nepafenac and Amfenac after Topical Administation of Nepafenac in the Rabbit. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5999.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the periocular distrubtion of the amide prodrug, nepafenac, and its active metabolite, amfenac, following topical ocular administration.
Single topical ocular doses of 0.1% nepafenac ophthalmic suspension were instilled unilaterally in New Zealand White rabbits. Ocular tissue samples were collected from both dosed (OD) and undosed (OS) eyes at intervals out to 48 hours. Nepafenac and amfenac tissue concentrations were determined by a validated LC/MS/MS method.
Peak amfenac concentrations were reached within 1 hour in the anterior segment and within 1-4 hours in the posterior segment. Unilateral dosing showed higher tissue levels in the dosed eye versus the undosed eye indicating appreciable local periocular distribution. A concentration-gradient was observed in the posterior segment, with highest peak concentrations in sclera followed by choroid and then retina. High and sustained concentrations of the prodrug were observed in the conjunctiva, cornea, and sclera, suggesting a depot for continued hydrolysis to the potent COX inhibitor amfenac. Very low vitreous concentrations of both drugs indicate that the posterior segment likely received drug via trans-scleral penetration.
Following topical instillation, nepafenac and amfenac are readily available to ocular tissues, including the posterior segment, reaching pharmacologically relevent concentrations through scleral and corneal penetration.
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