4-(Phenylmethyl)-1-piperazineacetic Acid 2-[[3-(2,3-Dihydroxypropyl)-2-hydroxyphenyl]methylene]hydrazide-d8 is deuterium labelled4-(Phenylmethyl)-1-piperazineacetic Acid 2-[[3-(2,3-Dihydroxypropyl)-2-hydroxyphenyl]methylene]hydrazide (P479905)and has been employed to characterize the in vivo and in vitro metabolic profile of PAC-1 (P132000), an anti-tumor agent that induces apoptosis.