title: The pharmacokinetics of [3H]-vincristine in man.
abstract: The pharmacokinetics, metabolism, and excretion of aromatically labeled tritiated vincristine (VCR) was examined in 4 patients. Clearance of radioactivity from the blood was triphasic with half-life t1/2 values of 0.85, 7.4, and 164 min. The initial phases probably represent distribution and binding to formed blood elements which exceeded 50% of the administered dose by 20 min. Excretion of radioactivity was principally fecal, with 33% recovered in the feces by 24 hr and 69% by 72 hr. Considerably less radioactivity (12%) was excreted in the urine over the 72-hr period. Approximately 40% of fecally excreted and 46% of urinary excreted radiolabel represented metabolites, which suggests that at least 34% of the VCR dose was excreted as metabolies. Plasma metabolites represented from less than 1% to 30% or more of radioactivity in plasma. Ultraviolet spectral analysis of all metabolites revealed preservation of the intact VCR dimer, which suggests that metabolism involves alteration of side groups.
mesh_terms: D000328:Adult; D005243:Feces / Q000032:analysis; D005260:Female; D006207:Half-Life; D006801:Humans; D007700:Kinetics; D008223:Lymphoma / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D014316:Tritium; D014750:Vincristine / Q000097:blood / Q000378:metabolism* / Q000652:urine
chemical_list: D014316:Tritium; D014750:Vincristine