Elacridar is primarily used to enhance the effectiveness of certain drugs by inhibiting efflux pumps in cells, particularly P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). This inhibition helps increase the absorption and bioavailability of co-administered drugs that are substrates of these transporters. It is commonly used in research to overcome multidrug resistance in cancer cells, allowing chemotherapy agents to accumulate more effectively inside tumor cells. Elacridar is also employed in preclinical studies to improve the brain penetration of drugs, making it valuable in central nervous system drug development. Additionally, it supports pharmacokinetic studies by modulating drug distribution and elimination, thereby helping scientists understand the role of efflux transporters in drug behavior.