Transporter-mediated drug uptake and efflux: important determinants of adverse drug reactions.

Transporter proteins mediate the cellular uptake and efflux of a broad variety of endogenous compounds, drugs, and their metabolites. Their systemic plasma concentrations are determined, in particular, by drug transporters expressed in the small intestine, liver, and kidney. In addition, drug transporters expressed in peripheral tissues (e.g., skeletal muscle) are likely to influence organ-specific drug concentrations and side effects. This review summarizes current findings regarding the association between adverse drug reactions in humans and modification of the functions of certain transporters caused by genetic factors or simultaneously administered inhibitors. We focus on adverse drug reactions occurring in humans due to transport in the small intestine, liver, kidneys, and blood-brain barrier.