Cerebrospinal fluid concentrations of vincristine after bolus intravenous dosing - A surrogate marker of brain penetration

BACKGROUND. Vincristine (VCR) is used widely in oncology practice, and regular dosing is commonly associated with the development of sensorimotor or autonomic neuropathies. However, the incidence of VCR-related central nervous system (CNS) toxicity is comparatively low, suggesting that the blood-brain barrier may limit drug penetration into the brain parenchyma. This study determined whether measurable concentrations of VCR could be detected in the cerebrospinal fluid (CSF), as a surrogate marker of brain parenchyma penetration, after bolus intravenous injection in children without primary CNS pathology.METHODS. The authors studied 17 pediatric patients ages 2.5-14.1 years (median, 6.8 years) with acute lymphoblastic leukemia or non-Hodgkin lymphoma without evidence of leptomeningeal disease. Patients received VCR 1.5 mg/m(2) by intravenous bolus injection followed at varying intervals by lumbar puncture for scheduled intrathecal methotrexate administration under general anesthesia. Paired VCR concentrations in both plasma and CSF were measured in each patient simultaneously at times ranging from 8 minutes to 146 minutes after the VCR injection. Three patients were studied twice. The paired samples were stored at -40 degreesC until analysis using a high performance liquid chromatography assay with a sensitivity of 0.1 mug/L in CSF and 0.4 mug/L in plasma.RESULTS. Plasma VCR concentrations ranged from 2.2 mug/L to 91.2 mug/L. No measurable VCR concentrations were detected in the CSF samples.CONCLUSIONS. Measurable concentrations of VCR in CSF are not achieved after the administration of standard intravenous bolus doses of VCR. The current observations are consistent with the relative rarity of VCR-related CNS neurotoxicity compared with the commonly observed sensorimotor and autonomic neuropathies. These findings suggest that the penetration of VCR into the brain parenchyma of patients with a relatively intact blood-brain barrier is low and that VCR may have a limited role in the CNS-directed therapy of these patients. (C) 2002 American Cancer Society