Transporter targeted drug delivery

The pharmacological behavior of various drugs is severely affected by biological barriers such as epithelial tight junctions, efflux proteins and metabolizing enzymes. Apart from the biological barriers, physicochemical properties of drug molecules such as molecular weight, lipophilicity, surface charge and solubility also play an important role in absorption characteristics of drug candidates. Pharmacological properties affected by efflux pumps such as P-gp and MRPs include bioavailability, hepatobiliary and urinary excretion of drugs as well as drug metabolites. This leads to sub-therapeutic concentrations of various potential drugs at the target site. One of the strategies to overcome these biological barriers is transporter targeted prodrug design. Prodrug derivatization targeting membrane transporters and receptors improves drug absorption. Various prodrugs which have been synthesized so far demonstrated enhanced bioavailability and tissue specificity. This review mainly focuses on the efflux pumps which play an important role in drug absorption and a few strategies to overcome these efflux pumps.