Methotrexate concentration in cerebrospinal fluid of the space created by tumor removal

This paper investigates the post-surgical pharmacokinetics of methotrexate (MTX) in the plasma, the cerebrospinal fluids (CSF), and the spaces created by tumor removal (STR) in patients with glioblastoma, during hyperosmotic disruption of the blood brain barrier (HODBBB) and intra-arterial chemotherapy with MTX. Eight Japanese patients with glioblastoma, three with open STRs and five with closed STRs, received a total of thirteen courses of HODBBB and intra-arterial combination chemotherapy with MTX. The patients were initially administered mannitol, then the anticancer drugs were infused into the carotid artery. Samples of blood and CSF from the STRs were obtained. MTX concentrations were measured by fluorescence polarization immunoassay and the pharmacokinetic parameters of MTX in plasma and CSF were estimated. The plasma concentrations of MTX peaked at the end of drug infusion, and then decayed bi-exponentially during the remainder of the treatment period. The CSF concentration of MTX in the STR peaked 2 h after drug administration, then mono-exponentially decreased. The area under the concentration-time curve (AUC) for plasma and CSF MTX concentrations increased in parallel with the MTX dose. In patients with open STRs, the mean AUC of MTX in CSF was 4.44% of that found in plasma, while in patients with closed STRs, the mean was 61.2% of that found in plasma. In the latter group, the MTX administered using HODBBB and intra-arterial chemotherapy was maintained in the STRs for long periods.