Isoniazid overdose: four case reports and review of the literature.
OBJECTIVE
To review the pathophysiology, presentation and treatment of isoniazid (INH) intoxication.


METHODS
Human, animal and modeling studies published since 1940 identified through MEDLINE and a review of the bibliographies of relevant articles.


METHODS
The studies identified were reviewed with emphasis on the most recent. Earlier studies were selected for their historical value and relevance to the clinical setting.


RESULTS
Isoniazid overdose is a potentially fatal intoxication. The incidence of tuberculosis has recently increased in the United States and therefore the frequency of INH overdose may also increase. Patients with INH overdose may present with nausea, vomiting, ataxia, symptoms reminiscent of atropine intoxication, coma and grand mal seizures. Lactic acidosis is revealed by laboratory evaluation. Treatment requires admission to the ICU for ventilatory support, and management of seizures and acid-base abnormalities. Pyridoxine, in a dose equivalent to the amount of INH ingested, is the only effective antidote.


CONCLUSIONS
INH overdose should be suspected in any patient presenting with seizures and metabolic acidosis. Prognosis is good when treatment is instituted early.
Pulmonary/Critical Care Department, Ben Taub General Hospital, Houston, Texas 77030, USA.
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FG
Alvarez
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Guntupalli
D000138:Acidosis / Q000209:etiology / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000995:Antitubercular Agents / Q000494:pharmacology / Q000506:poisoning*; D062787:Drug Overdose; D005260:Female; D006801:Humans; D007538:Isoniazid / Q000494:pharmacology / Q000506:poisoning*; D008297:Male; D011379:Prognosis; D011736:Pyridoxine / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D012640:Seizures / Q000188:drug therapy / Q000209:etiology
D000995:Antitubercular Agents; D011736:Pyridoxine; D007538:Isoniazid