Abstract
The preparation of tritium-labelled vinblastine by the Wilzbach irradiation method is described. Tritiated dihydrovinblastine was concurrently formed and could not be detected or separated from tritiated vinblastine by previously available methods. It is now found that tritiated vinblastine can be freed from the contaminating dihydro compound by chromatography on cellulose phosphate. The rate of urinary excretion of radioactivity by rats given injections of the purified alkaloid has been studied. About 5% of the dose radioactivity is excreted in the urine collected in the 12 hour period after injection; thereafter only very minor amounts of radioactivity are eliminated by this route.