Vinblastine Pharmacokinetics in Patients with Non-Small Cell Lung Cancer Given Cisplatin

Abstract The pharmacokinetics of vinblastine were studied in 16 patients with non-small cell lung cancer after a bolus intravenous dose of 3 mg/m2 given before or after cisplatin (100 mg/m2). Venous blood was collected at 0, 10, and 36 hr for analysis by radio-immunoassay. The mean plasma vinblastine concentration at 10 hr was similar when vinblastine was given before (4.8 ng/ml; 95% CI, 3.2-6.3) or after cisplatin (4.9 ng/ml; 95% CI, 2.7-7.1). Plasma vinblastine concentrations in patients given cisplatin were higher than previously reported in patients given vinblastine alone. Patients with plasma vinblastine concentrations less than 2.75 ng/ml at 10 hr experienced less severe neutropenia (37% fall in neutrophil count; 95% CI, 18-55) than those with levels greater than 2.75 ng/ml (69% fall in neutrophil count; 95% CI, 62-77). In conclusion. the pharmacokinetics of vinblastine predict the severity of neutropenia and may be altered when given in conjunction with cisplatin.