II. Pharmacokinetics
- Absorption rapid
- Peak levels: 1 to 2 hours
- Toxic Levels: >20 mg/kg
III. Mechanism: Toxicity
- Pyridoxine Deficiency
- Glutamic Dehydrogenase inhibition
IV. Symptoms
- Nausea
- Vomiting
- Altered Mental Status
- Ataxia
-
Seizures or Status Epilepticus
- Ingestions >20 mg/kg
- Rhabdomyolysis
V. Labs
- See Unknown Ingestion for broad based lab evaluation after ingestion
- Labs in isolated Isoniazid ingestion
- Bedside Glucose
- Basic metabolic profile
- Creatinine Phosphokinase
VI. Imaging
-
CT Head
- Consider in unknown cause of Altered Level of Consciousness or Status Epilepticus
VII. Diagnostics
-
Electroencephalogram (EEG) monitoring
- Indicated in persistant or recurrent Seizures
VIII. 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
IX. References
- Tomaszewski (2018) Crit Dec Emerg Med 32(7):28