TABLE 1

IC50 and Ki values of some representative ABCB1 inhibitors

InhibitorhABCG2cABCB1Ki Ratio (Ki,ABCG2/Ki,cABCB1)
IC50KiIC50Ki
μM
Tariquidar2.192.170.4910.4824.51
Cyclosporine A4.694.650.7880.7746.01
Zosuquidar>10>9.80.6170.606>16.2
Verapamil4174142.212.17191
  • Ki values for hABCG2 and cABCB1 were calculated by using the Km value of prazosin toward hABCG2 (i.e., 128 µM) and the Km value of digoxin toward cABCB1 (i.e., 53.9 µM), estimated from the Papp from the apical to basolateral side in MDCKII/hABCG2 and MDCKII/WT cells, respectively.