Phenelzine in urine: assay and relation to acetylator status.

Phenelzine cannot be extracted as such from biological fluids. Formation of the acetonide derivative prior to extraction allows phenelzine to be extracted and assayed by gas chromatography at levels down to 0.5 microg/ml. At this sensitivity the drug can be detected in urine but not in plasma, after therapeutic doses. Persons typed as slow acetylators of sulphadimidine excreted approximately twice as much unmetabolized phenelzine in urine compared to fast acetylators.