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Isoniazid Poisoning
Aka: Isoniazid Poisoning, Isoniazid Overdose, Isoniazid Toxicity
- See Also
- Isoniazid
- Pharmacokinetics
- Absorption rapid
- Peak levels: 1 to 2 hours
- Toxic Levels: >20 mg/kg
- Mechanism: Toxicity
- Pyridoxine Deficiency
- Glutamic Dehydrogenase inhibition
- Blocks conversion of glutamate to GABA
- Results in GABA deficiency
- Symptoms
- Nausea
- Vomiting
- Altered Mental Status
- Ataxia
- Seizures or Status Epilepticus
- Ingestions >20 mg/kg
- Rhabdomyolysis
- Labs
- See Unknown Ingestion for broad based lab evaluation after ingestion
- Labs in isolated Isoniazid ingestion
- Bedside Glucose
- Basic metabolic profile
- Creatinine Phosphokinase
- Imaging
- CT Head
- Consider in unknown cause of Altered Level of Consciousness or Status Epilepticus
- Diagnostics
- Electroencephalogram (EEG) monitoring
- Indicated in persistant or recurrent Seizures
- Management
- Decontamination
- Activated Charcoal 1 g/kg if presenting within one hour of ingestion, and airway protected
- Consider Hemodialysis if started early in large ingestions
- Pyridoxine
- Give same dose of Pyridoxine of the Isoniazid ingestion if known OR
- Pyridoxine 70 mg/kg (up to 5 g) IV over 3 to 5 minutes
- May repeat dosing for recurrent Seizures
- Seizures
- See Status Epilepticus
- Lorazepam 0.5 to 1 mg/kg (up to 2 mg/dose) as needed
- Disposition
- Observe or admit all patients with recurrent Seizures or persistent Altered Mental Status
- May discharge after 4 to 6 hours following ingestion if asymptomatic
- References
- Tomaszewski (2018) Crit Dec Emerg Med 32(7):28