Substance
Isoniazid (one of the anti-TB regimen, some are accidental.
Some are intentional)
- Accounts for 5% of Intoxication related seizure
Common name or Trade
name
INH
Involving system
- In adults, toxicity can occur
with the acute ingestion of as little as 1.5 g of isoniazid. [1]
- ingested in amounts of 80 to 150 mg
per kg or more, isoniazid can be rapidly fatal. [1]
- CNS: Doses larger than 30 mg per kg
often produce seizures. [1]
Mechanism: This reduction in GABA
levels increases the susceptibility to seizures. [1]
Presentation
- nausea, vomiting, slurred speech,
dizziness, tachycardia, and urinary retention
- stupor [1]
- seizure [1, 2]
- intractable seizure, acidosis, metabolic
acidosis and coma [1, 3, 4]
- dementia [5]
- status epilepticus in children [6]
- elevated anion gap and metabolic
acidosis, hyperglycemia, hypokalemia, glucosuria, and ketonuria [1]
Antidote and
Treatment
- Decontamination, irrigation, Charcoal
50 gm, 1gm/ kg
- BZD for seizure, valium IV.
- pyridoxine intravenously [6]
- If the amount of ingested isoniazid is
unknown, 5 g of pyridoxine
is given intravenously over five to 10 minutes [1]
(Dose: Given in gram-per-gram amounts of the isoniazid ingested,
pyridoxine (vitamin B6) usually eliminates seizure activity and helps to
correct the patient's metabolic acidosis. [1])
Mechanism: - pyridoxine is a necessary cofactor for the production of the
neurotransmitter gamma-aminobutyric acid (GABA). Pyridoxine must be activated to
produce GABA. [1]
- NaHCO3-, if the ABG pH is less than
7.1. A good starting dose is 1 to 3 mEq per kg
- continuous veno-venous
hemodiafiltration [2]
Disposition
- consult social worker, psychiatrist,
suicide prevention unit.
- Depends individualized.
REFERENCES
[1] Romero JA, Kuczler FJ Jr. Isoniazid
overdose: recognition and management. Am Fam Physician. 1998 Feb
15;57(4):749-52. PMID: 9490997.
[2]. Skinner K, Saiao A, Mostafa A,
Soderstrom J, Medley G, Roberts MS, Isbister GK. Isoniazid poisoning:
Pharmacokinetics and effect of hemodialysis in a massive ingestion. Hemodial
Int. 2015 Oct;19(4):E37-40. doi: 10.1111/hdi.12293. Epub 2015 Mar 16. PMID:
25779481.
[3]. Khoharo HK, Ansari S, Abro A, Qureshi
F. Suicidal Isoniazid poisoning. J Ayub Med Coll Abbottabad. 2009 Apr-Jun;21(2):178-9.
PMID: 20524502.
[4] Kürşad H, Kizilkaya M, Sahin M, Dogan N, Ilgaz A. Treatment of acute isoniazid toxicity of unknown dose. South Med J. 2003 Jan;96(1):101. doi: 10.1097/01.SMJ.0000049841.49028.41. PMID: 12602731.
[5]. McLay RN, Drake A, Rayner T.
Persisting dementia after isoniazid overdose. J Neuropsychiatry Clin Neurosci.
2005 Spring;17(2):256-7. doi: 10.1176/jnp.17.2.256. PMID: 15939987.
[6] Caksen H, Odabas D, Erol M, Anlar O,
Tuncer O, Atas B. Do not overlook acute isoniazid poisoning in children with
status epilepticus. J Child Neurol. 2003 Feb;18(2):142-3. doi:
10.1177/08830738030180021101. PMID: 12693784.
~~~~~~~ edited by Yu-Jang Su Oct 31, 2020 ~~~~~~
