Isoniazid is one of the most commonly used antituberculous drugs. Acute intoxication is characterized by repetitious convulsions, high anion gap metabolic acidosis and coma. The basis of therapy consists of parenteral pyridoxine administration in a dose equivalent to that of isoniazid ingested. Here we present a case of acute isoniazid intoxication presenting with convulsions and metabolic acidosis with consequent rhabdomyolysis and discuss the clinical signs and pathophysiology of isoniazid intoxication.

Isoniazid is one of the most commonly used antituberculous drugs. Acute intoxication is characterized by repetitious convulsions, high anion gap metabolic acidosis and coma. The basis of therapy consists of parenteral pyridoxine administration in a dose equivalent to that of isoniazid ingested. Here we present a case of acute isoniazid intoxication presenting with convulsions and metabolic acidosis with consequent rhabdomyolysis and discuss the clinical signs and pathophysiology of isoniazid intoxication.