ATP-binding cassette sub-family B member 1 and ATP-binding cassette sub-family G member 2 (ABCB1 and ABCG2)

ABCB1 (P-glycoprotein, MDR1) and ABCG2 (breast cancer resistance protein, BCRP) are members of the ATP-binding cassette (ABC) transporter superfamily involved in cellular efflux of a wide range of structurally diverse xenobiotics and endogenous compounds. ABCB1 is found in tissues with barrier function (intestine, liver, kidney, blood–brain barrier, placenta) and plays a dominant role in extruding drugs and toxins, contributing significantly to multidrug resistance in cancer and influencing pharmacokinetics of many medications. ABCG2 has a similarly broad substrate specificity and is implicated in multidrug resistance in various cancers, the transport of urate and heme, and in the physiological excretion of toxins and metabolites. Both transporters are key determinants of drug absorption, distribution, and elimination, and genetic variation or overexpression is associated with clinical drug resistance and variable therapeutic responses.

Other names

ABCB1: P-glycoprotein (P-gp)MDR1ABCG2: Breast cancer resistance protein (BCRP)

- Efflux pump inhibition: Inhibitors (e.g., verapamil, tariquidar, elacridar) block drug export, increasing intracellular drug concentrations. - Substrate competition: Co-administered drugs compete for transporter-mediated efflux, altering pharmacokinetics and drug-drug interactions.