In Vitro Characterization of Renal Transporters OAT1, OAT3, and OCT2

The human transporters organic anion transporter 1 (OAT1), organic anion transporter 3 (OAT3) and organic cation transporter 2 (OCT2) are membrane proteins involved in the renal clearance of substances from the body. While the original purpose of these clearance pathways was likely the removal of naturally occurring metabolism byproducts, they are also responsible for secretion of many drugs. Various assay systems have been developed to study the interactions of drugs with these transporters as either substrates or inhibitors, since a reduction in drug clearance (due to inhibition of transport of one drug by a co-administered drug) could result in elevated exposure and toxicity. This chapter will provide a brief background on the transporters and how they function, highlight the importance of using in vitro test systems to evaluate the potential for drug-drug interactions (DDIs), and provide a detailed procedure for an assay using transfected human embryonic kidney (HEK293) cells.