Absolute bioavailability studies of a new oral topotecan formulation in Chinese patients using UHPLC-MS/MS

► The absolute bioavailability of a new oral topotecan formulation was estimated. ► The pharmacokinetics of oral topotecan in Chinese patients was first studied. ► A sensitive and time saving UPLC-MS/MS assay has been developed. ► The conversion between the lactone and carboxylate forms of topotecan was studied. ► The present study builds a bridge for further clinical research of oral topotecan.