The pharmacokinetics of vinblastine in humans was examined using a radioimmunoassay specific for both the Vinca alkaloids and aromatic ring [3H]vinblastine. The data were consistent with a three-compartment open model system with the following values. α phase: t1/2 = 3.90 ± 1.46 min; Vc = 16.8 ± 7.1 liters. β phase: t1/2 = 53.0 ± 13.0 min; Vβ = 79.0 ± 52.0 liters; γ phase: t1/2 = 1173.0 ± 65.0 min; Vγ = 1656.0 ± 717.0 liters. Most significant was the finding that vinblastine is metabolized to deacetylvinblastine and that this compound is more biologically active on a weight basis than the parent. No other biologically active metabolites appeared to be present in urine or in stool.
This research was supported in part by USPHS Grant CA-16157 from the National Cancer Institute, NIH, and in part by The Eli Lilly and Co., Indianapolis, Ind.