Administration of oral cyclosporine A (15 mg/ kg), an inhibitor of transporters ABCB1 (P-gp) and ABCC1 (MRP-1) as well as the metabolising enzyme CYP3A4, within 4 hours of oral topotecan increased the dose normalised AUC0-24h of topotecan lactone and total topotecan approximately 2.0- and 2.5-fold respectively (see section 4.5).