Following coadministration of the ABCB1 (P-gp) and ABCG2 (BCRP) inhibitor, elacridar (GF120918) at 100 to 1,000 mg with oral topotecan, the AUC0- ∞ of topotecan lactone and total topotecan increased approximately 2.5-fold (see section 4.5 for guidance).