Abstract
Abstract: :
Purpose: To study the effect of intraocular pressure changes on transcorneal penetration of topically applied drugs. Methods: Eight Albino rabbits (2.0–2.5 kg) were sacrificed and their eyes enucleated. The freshly excised corneas were mounted horizontally beneath a humidity controlled donor chamber and above a pressure controlled acceptor chamber of an ex vivo diffusion apparatus, with the endothelial side facing balanced salt solution (BSS–plus, Alcon Labs. Inc., Fort Worth, TX, USA) filled acceptor chamber. One microliter of 4% gentamicin as sulphate (Rafa Labs. Ltd., Jerusalem, Israel) was applied on the center of the epithelial surface of the mounted cornea at various pressure levels of acceptor chamber (0, 20, 40, 60 mm Hg; 4 corneas for each pressure level). After 60 minutes, the concentration of gentamicin in the acceptor chamber fluid was measured by fluorescence polarization immunoassay using a TDx System Analyzer (Abbott labs., Irving, TX, USA). Results: Best transcorneal gentamicin sulphate penetration was achieved at acceptor chamber pressure of 20 mm Hg, with less penetration at higher pressure levels. When the pressure in the acceptor chamber was lowered to the zero level, the drug penetration was relatively poor. Conclusions: Ex vivo transcorneal drug penetration studies should include transcorneal pressure setting that simulates physiological intraocular pressure.
Keywords: pharmacology • cornea: basic science • intraocular pressure