Elacridar is primarily used to enhance the absorption and bioavailability of drugs that are substrates of P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). It acts as a potent inhibitor of these efflux transporters, which are often responsible for limiting the entry of certain medications into the brain and intestines. This property makes Elacridar valuable in research settings, especially in oncology and neuropharmacology, where it helps improve the effectiveness of chemotherapeutic agents by preventing their expulsion from cancer cells. It is also used in preclinical studies to investigate blood-brain barrier penetration, enabling a better understanding of drug distribution in the central nervous system.