Isoniazid toxicity: A treatable cause of status epilepticus

Article type: Research Article

Authors: Basu, Biswanath

Affiliations: Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India

Note: [] Correspondence: Biswanath Basu, MD, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India. Tel.: +91 9236123377; E-mail: [email protected]

Abstract: A 4-year-old child with history of accidental ingestion of 13 tablets isoniazid-rifampicin (89 mg/kg isoniazid), 1 hr earlier, presented with generalized tonic-clonic seizure, which was refractory to diazepam, phenytoin and phenobarbitone. Given in gram per gram amounts of the isoniazid ingested, intravenous pyridoxine (vitamin B_{6}) ultimately terminated the seizure activity. Isoniazid inhibits brain pyridoxal-5-phosphate, the active form of pyridoxine, resulting in decrease in the brain level of gamma aminobutyric acid causing decrease in seizure threshold. Isoniazid toxicity should be suspected in any patient who presents with refractory seizure and physicians must be prepared to counteract the potentially fatal toxic effects with pyridoxine.

Keywords: Isoniazid, status epilepticus, pyridoxine

DOI: 10.3233/JPN-2009-0305

Journal: Journal of Pediatric Neurology, vol. 7, no. 3, pp. 315-316, 2009