In methanol poisoning, when the initial course of antidote-based management does not achieve the expected reduction in serum methanol or restoration of normal arterial pH, a defined escalation step is indicated. The following outlines the failure condition and the goals that guide the next intervention.
First-line management — inhibition of methanol metabolism with an antidote together with folinic acid and correction of metabolic acidosis — is considered insufficient when serum methanol concentration has not been reduced to below 20 mg/dL with the patient asymptomatic, or when arterial pH has not been corrected to the normal range of 7.35–7.45. Meeting neither target signals the need for escalation.
Escalation centres on an extracorporeal blood-purification procedure that works to correct the acid–base imbalance and accelerate elimination of the circulating toxic metabolite. The antidote must be continued at adjusted dosing during the procedure to account for altered clearance. The complete protocol — including precise indications, dosing adjustments, and management sequence — is available via the link below.
Serum methanol concentration undetectable or below 25 mg/dL, with disappearance of the acid–base imbalance and full correction of metabolic acidosis.
Hemodialysis has been used routinely to correct acidosis, to remove the toxic metabolite, formate, and to shorten the course of hospitalization by removing methanol.
Increased administration of ethanol (or the addition of 95% ethanol to the dialysate) is necessary to counteract its loss during dialysis.
Increased fomepizole dosing is also necessary during this procedure.
Table 4 outlines the U.S. manufacturer's recommended dosing schedule of fomepizole during hemodialysis when the dosing interval of fomepizole should be 4-hourly.
The traditional endpoint for dialysis is an undetectable serum methanol concentration or a concentration below 25 mg/dL (250 mg/L) with the disappearance of acid–base imbalance.
Correction of the anion gap metabolic acidosis and the osmolar gap are adequate endpoints for dialysis, particularly when the patient is receiving fomepizole or ethanol and the serum methanol or formate concentrations are unavailable.
View source ↗