Detection and identification of some metabolites of <i>iso</i>nicotinic acid hydrazide (isoniazid) in human urine

Kelly, Poet & Chesner (1952) have investigated the metabolic fate of isoniazid (pyridine-4-carboxy- hydrazide)' in dogs. After the oral administration of isoniazid (5 and 20 mg./kg. body weight), 20-50 % of the drug was excreted unchanged in the first and 1-5 % in the second 24 hr. isoNicotinic acid was isolated and identified as a major metabolite, 20-40 % ofthe dose being excreted in this form. They