The pharmacokinetics of vinblastine were studied in 16 patients with non-sm
all cell lung cancer after a bolus intravenous dose of 3 mg/m(2) given befo
re or after cisplatin (100 mg/m(2)). Venous blood was collected at 0, 10, a
nd 36 hr for analysis by radioimmunoassay. The mean plasma vinblastine conc
entration 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 pre
viously reported in patients given vinblastine alone. Patients with plasma
vinblastine concentrations less than 2.75 ng/ml at 10 hr experienced less s
evere 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 seve
rity of neutropenia and may be altered when given in conjunction with cispl
atin.