Tissue levels and some pharmacological properties of an acetylated metabolite of phenelzine in the rat. 
The metabolic generation of N2-acetylphenelzine by rats treated with phenelzine, and the activity of this metabolite as an inhibitor of monoamine oxidase enzymes in vivo were confirmed.  The isomeric amide N1-acetylphenelzine was not a metabolic product of phenelzine and also did not inhibit monoamine oxidase enzymes.  Levels of N2-acetylphenelzine in rat blood, after treatment with a dose (0.1 mmol.kg-1) of N2-acetylphenelzine sufficient to inhibit monoamine oxidase enzymes but not to increase brain levels of dopamine or noradrenaline, were higher than those generated metabolically from a higher dose (0.38 mmol.kg-1) of phenelzine which did increase brain levels of these biogenic amines.  Metabolically derived N2-acetylphenelzine, therefore, probably does not contribute in any significant way to monoamine oxidase inhibition by phenelzine.