ON THE METABOLIC FATE OF ISONIAZID

¹ The Christ Hospital Institute of Medical Research, Cincinnati, Ohio

This report deals with studies on the excretion and metabolism of isoniazid in the rhesus monkey. These studies have demonstrated that the equivalent of from 50 to 100 per cent of orally administered isoniazid is eliminated in the urine. The major component of this excretion has been isolated and identified as 1-isonicotinyl-2-acetylhydrazine. It was found in the urine of one patient to the extent of 91 per cent of the isoniazid-like materials excreted, so it is not unlikely that this acetyl derivative is the major metabolic product in man. The significance of this finding as it relates to the toxicity and chemotherapeutic activity of isoniazid and to previous work on the metabolic fate of this drug has been discussed.