Transscleral drug delivery to the posterior eye: Prospects of pharmacokinetic modeling

Basic biological research has provided new approaches to treat severe diseases of the retina and choroid, such as age related macular degeneration. Although it is possible to deliver drugs from a subconjunctival drug depot to the retina and choroid, the barriers and kinetics of this route of drug administration are not well known. In this review we investigate the pharmacokinetic aspects of transscleral drug delivery into the posterior eye with emphasis on pharmacokinetic modeling. The existing simulation models related to the transscleral drug delivery are reviewed and future directions for the model development are discussed. In addition, a new simulation model for the transscleral drug delivery based on permeability data is introduced. This compartmental model contains several ocular tissues (sclera, choroid, retinal pigment epithelium and vitreous) and it takes into account the clearance of the drug via choroidal circulation. The model is used to simulate the vitreous delivery of macromolecules based on the available data on FITC-dextran 70 kDa.