CP-671,305 is identified as a substrate of MRP2 and BCRP, but not MDR1. CP-671,305 is a substrate of human OATP2B1 with a high affinity (Km=4 μM) but not a substrate for human OATP1B1 or OATP1B3. CP-671,305 displays high affinity (Km=12 μM) for rat hepatic Oatp1a4. CP-671,305 does not exhibit competitive inhibition of the five major cytochrome P450 enzymes, namely CYP1A2, 2C9, 2C19, 2D6 and 3A4 (IC50s > 50 μM). Likewise, no time-dependent inactivation of the five major cytochrome P450 enzymes is discernible with CP-671,305.