An anthranilamide derivative with multidrug resistance properties. Tariquidar non-competitively binds to the p-glycoprotein transporter, thereby inhibiting transmembrane transport of anticancer drugs. Inhibition of transmembrane transport may result in increased intracellular concentrations of an anticancer drug, thereby augmenting its cytotoxicity. or A substance that is being studied in the treatment of cancer. It may help tumor cells respond again to drugs they have become resistant (unable to respond) to. Tariquidar is a type of multidrug resistance inhibitor and a type of P-glycoprotein antagonist. Also called XR9576.