Detection and quantitation of a ring-hydroxylated metabolite of the antidepressant drug tranylcypromine.

The formation of p-hydroxytranylcypromine from intraperitoneally injected tranylcypromine was confirmed using two types of experiments. In the first, tranylcypromine levels were shown to be increased in brains of rats pretreated with agents known to be inhibitors of ring hydroxylation compared to rats pretreated with physiological saline. For the second set of experiments, p-hydroxytranylcypromine was identified in brain and urine (following intraperitoneal injection) by derivatizing with perfluoroacylating reagents and analyzing by electron-capture gas chromatography and by combined gas chromatography-mass spectrometry. In experiments in vitro, p-hydroxytranylcypromine was demonstrated to inhibit monoamine oxidase, although it was weaker than TCP in this regard and was a much stronger inhibitor of MAO-A than of MAO-B.