Suicide attempt with isoniazid in adolescents receiving tuberculous prophylaxis: three cases

An overdose of isoniazid (INH) is potentially fatal and attempts at suicide are very rare in children. Three patients aged 14-17 years who were receiving INH for tuberculosis prophylaxis were admitted to the emergency department with generalised tonic-clonic seizures. There was metabolic acidosis and elevated levels of blood creatine kinase, aminotransferases and lactate dehydrogenase following ingestion of excess INH in attempts at suicide. The presumed total amounts of INH ingested were 3 g (40 mg/kg), 9 g (160 mg/kg) and 6 g (100 mg/kg), respectively. They all improved with general supportive measures including airway protection, gastric lavage, activated charcoal administration, sodium bicarbonate infusion, fluid replacement, seizure control and pyridoxine administration. They were discharged without complications. Attempts to commit suicide by excess intake of INH is rare in children but should be considered in the differential diagnosis of acute intractable seizures and metabolic acidosis refractory to conventional anticonvulsant therapy in adolescents.