see also: > [!important] Key Points > - **risk_dose**:: >10g (150mg/kg) may be fatal if untreated; <1.5g usually mild tox > - **Antidote**:: [[Pyridoxine]] 5g IV over 3-5 min > - **key_points**:: used for treating [[Tuberculosis]] > - [mnemonic::] # Risk assessment # Toxic Mechanism # Clinical features - 1/2-3 hrs following ingestion - nausea, vomiting - CNS - slurred speech - dizziness - ALOC - hyperreflexia - [[Seizures#Toxicological Seizures|seizures]] - metabolic - [[Blood gas#Metabolic acidosis]] - 2/2 seizure - inhibition of converting lactate → pyruvate - [[hyperglycaemia|hyperglycemia]] #hyperglycaemia - other - hypotension - resp depression - [[Heat-related illness|hyperthermia]] ## Seizures - due to depression of GABA levels by inhibition of pyridoxal-5-phosphate - lower doses can cause toxicity in pts with preexisting seizure disorders, vitamin B6 def, or chronic alcoholism # Treatment - activated charcoal - **[[Pyridoxine]]** - give to all patients with evidence of toxicity - tx seizures: benzos, then pyridoxine - avoid phenytoin b/g INH decreases its metabolism - [[haemodialysis]] in severe toxicity resistant to conventional therapy # Disposition - expectant inf no signs of toxicity 4 hours after ingestion of < 20mg/kg - admit to hospital if: - \> 80mg/kg ingested - features of toxicity