1997 Volume 12 Issue supplement Pages 100-101
The purpose of this study is to characterize the ocular membrane permeability and absorption of ophthalmic drug. Male albino rabbits were used throughout the study.
The in vitro penetrations of beta-blockers were measured across the isolated corneal and conjunctival membranes using a two-chamber glass diffusion cell. The lipophilic character of the corneal barrier was determined by the partition parameter of beta-blockers, not by the diffusion parameter. Ocular permeability coefficients of peptide drugs and hydrophilic macromolecules were extremely lower than those of beta-blockers. Ocular membranes have been also characterized by in situ absorption of beta-blockers using a cylindrical cell. As the results, the corneal route was a dominant route of access to the aqueous humor. A pharmacokinetic model including the diffusion process for ocular drug delivery was demonstrated. Distribution volume and elimination rate of tilisolol and timolol in tear fluid and aqueous humor were estimated by instillation of drug and injection of drug into the anterior chamber. The in vivo permeability parameters for tilisolol and timolol were estimated from the model.
