Advances in the study of blood-retinal barrier transporters

Drug deliver to the posterior eye segment (retinal tissue and vitreous) via systemic administration is constrained due to the presence of blood-retinal barrier (BRB), which regulates the permeation of many substances from blood to retina selectively.Two major transporters have been identified in the human genome, and they are solute carrier superfamilies and ATP-binding cassette.As the function of transporters is being revealed, it has been clarifed that the transporters are very important in pharmacokinetics.This article reviewed the expression and functional activity of various BRB transporters, including amino acid, oligopeptide, monocarboxylate, folate, nucleoside transporters etc., updated the current knowledge about the BRB transporters and elucidated the urgent need for the development of optimal and efficient drug delivery systems.Any approach to further improving the ocular bioavailability of drugs will be of significant clinical relevance.