›Patient asymptomatic
›pH normal and anion gap resolving
›Caution: do NOT use polycarbonate syringes or needles with fomepizole
›Drug interaction with polycarbonate material
›Fomepizole alone prolongs methanol half-life to approximately 71 hours
›Extended hospitalization expected without HD
Antidotal therapy — IV ethanol (alternative)
›IV ethanol — if fomepizole unavailable
›Mechanism: preferential substrate for alcohol dehydrogenase
›Competes with methanol to block formate production
›Target serum ethanol: 100 mg/dL (21.7 mmol/L)
›Loading dose: 10% ethanol in D5W, 7.6 mL/kg IV over 30-60 minutes
›Adjust for estimated blood ethanol if already present
›Maintenance infusion:
›Non-drinker: 0.83 mL/kg/hour of 10% ethanol
›Chronic drinker: 1.4 mL/kg/hour of 10% ethanol
›Increase rate during hemodialysis (ethanol removed by HD)
›Monitoring requirements:
›Serum ethanol level every 1-2 hours
›Blood glucose every 1-2 hours (hypoglycemia risk)
›ICU-level nursing monitoring required
›Sodium bicarbonate
›Indication: pH < 7.3 or bicarbonate < 20 mmol/L
›Reduces ionized formate, decreasing CNS and optic nerve penetration
›Increases renal formate excretion
›Initial dose: 1-2 mmol/kg IV bolus
›Repeat as needed to maintain pH > 7.35
›Sodium bicarbonate infusion: 150 mmol in 1L D5W at 250 mL/h
›Titrate to serial ABG results
›Folic acid (leucovorin)
›Dose: 1 mg/kg IV (maximum 50 mg) every 4-6 hours
›Enhances formate metabolism via tetrahydrofolate pathway
›Promotes conversion of formate to CO2 and H2O
›Continue until methanol undetectable and patient asymptomatic
›If leucovorin unavailable, folinic acid acceptable alternative
›Hemodialysis — definitive elimination therapy
›Indications (EXTRIP 2015 consensus — Strong Recommendation):
›Coma or seizures
›New or worsening visual deficits
›pH <= 7.15
›Anion gap > 24 mmol/L refractory to treatment
›Serum methanol > 15.6 mmol/L (50 mg/dL)
›Impaired renal function
›Intermittent HD preferred over continuous renal replacement therapy
›Methanol half-life: 3.7 hours with intermittent HD vs 8.1 hours with CVVHD
›Zakharov et al., Kidney International 2014
›Session duration: 4-8 hours or until methanol < 6.2 mmol/L (20 mg/dL)
›Continue fomepizole (dosed q4h) and folic acid during HD
›Avoid systemic anticoagulation during HD if possible
›Risk of intracerebral hemorrhage in basal ganglia necrosis
›Terminate HD when:
›Methanol < 6.2 mmol/L (20 mg/dL)
›pH > 7.35 and anion gap normalized
›Clinical improvement confirmed
›Post-HD methanol rebound
›Check methanol level 1-2 hours post-HD (redistribution from tissues)
›If rebound > 6.2 mmol/L with symptoms, repeat HD session
›Activated charcoal — generally not recommended
›Methanol rapidly absorbed from GI tract (within 30-60 minutes)
›Charcoal does not bind alcohols well
›Risk of aspiration in obtunded patients outweighs benefit
›Gastric lavage — not routinely recommended
›Only if patient presents within 1 hour of ingestion and airway protected
›Evidence base weak