Used to reverse multidrug resistance in cancer therapy by inhibiting P-glycoprotein, a drug efflux pump that reduces the effectiveness of chemotherapy agents. By blocking this pump, it helps increase the intracellular concentration of anticancer drugs, enhancing their cytotoxic effects. Investigated in clinical trials for use with chemotherapeutics in resistant forms of leukemia, solid tumors, and other malignancies. Also employed in research to study drug transport mechanisms and improve delivery of therapeutics across biological barriers.