Corneal permeability of ketorolac tromethamine when formulated with tobramycin

Abstract

In vitro rabbit corneal penetration studies were designed to determine the effect tobramycin (an antibiotic) has on the diffusion of ketorolac tromethamine (a nonsteroidal anti-inflammatory compound). Evaluation was performed in two vehicle solutions: (1) a simple sodium chloride vehicle and (11) a suitable ophthalmic formulation. Quantitation of both ketorolac tromethamine and tobramycin were performed to determine the corneal penetration of each drug. Tobramycin was found to penetrate rabbit cornea to a limited extent. Also, tobramycin proved neither to impede nor enhance ketorolac's corneal diffusion. Both compounds showed greater penetration in an ophthalmic formulation, presumably due to the effects of the preservative, benzalkonium chloride (a quaternary ammonium compound)—known for disrupting corneal integrity.