ISONIAZID OVERDOSE - 4 CASE-REPORTS AND REVIEW OF THE LITERATURE

Objectives: To review the pathophysiology, presentation and treatment of isoniazid (INH) intoxication. Data sources: Human, animal and model ing studies published since 1940 identified through MEDLINE and a revi ew of the bibliographies of relevant articles. Study selection and dat a extraction: The studies identified were reviewed with emphasis on th e most recent. Earlier studies were selected for their historical valu e and relevance to the clinical setting. Data synthesis: Isoniazid ove rdose is a potentially fatal intoxication. The incidence of tuberculos is has recently increased in the United States and therefore the frequ ency of INH overdose may also increase. Patients with INH overdose may present with nausea, vomiting, ataxia, symptoms reminiscent of atropi ne intoxication, coma and grand mal seizures. Lactic acidosis is revea led by laboratory evaluation. Treatment requires admission to the ICU for ventilatory support, and management of seizures and acid-base abno rmalities. Pyridoxine, in a dose equivalent to the amount of INH inges ted, is the only effective antidote. Conclusions: INH overdose should be suspected in any patient presenting with seizures and metabolic aci dosis. Prognosis is good when treatment is instituted early.