Topotecan lactone pharmacokinetic variables (A) Area under the plasma concentration-time curve (AUCinf) (B) Systemic clearance (CL) and (C) Volume of distribution (Vd) in male C57BL/6 WT, Abcc2−/−, Abcc4−/−, Abcb1−/−, Abcg2−/−, Abcc2;Abcg2, Abcc4;Abcg2−/− and Abcc2;Abcb1−/− mice, after IV administration of 1 mg/kg and 4 mg/kg topotecan. The pharmacokinetic parameters were estimated by noncompartmental analysis using WinNonlin Professional Version 5.2. The statistical differences were determined using the One-Way ANOVA with Tukey's multiple comparison (GraphPad Prism version 5.04) tests to compare inter-strain differences. Data are expressed as mean values of the AUC, CL or Vd ± SD (n = 5–9; *, P < 0.05; **, P < 0.01; ***, P < 0.001 compared with wild-type; #, P < 0.05; ##, P < 0.01; ###, P < 0.001 compared with Abcc2−/−).