Tariquidar dihydrochloride is primarily utilized in the field of cancer research and treatment. It functions as a potent inhibitor of P-glycoprotein, a protein that contributes to multidrug resistance in cancer cells. By blocking this protein, it enhances the effectiveness of chemotherapeutic agents, allowing them to accumulate in cancer cells and exert their cytotoxic effects. This makes it a valuable tool in overcoming drug resistance, particularly in cancers like breast, ovarian, and lung cancer, where P-glycoprotein overexpression is common. Additionally, it is used in preclinical studies to investigate the mechanisms of drug transport and resistance, aiding in the development of more effective cancer therapies.