Objective: To assess the efficacy and safety of fomepizole, a competitive alcohol dehydrogenase inhibitor, in methanol poisoning and to test the hypothesis that fomepizole obviates the need for hemodialysis in selected patients.
Design and setting: Retrospective clinical study in three intensive care units in university-affiliated teaching hospitals.
Patients: All methanol-poisoned patients admitted to these ICUs and treated with fomepizole from 1987-1999 (n=14).
Measurements and results: The median plasma methanol concentration was 50 mg/dl (range 4-146), anion gap 22.1 mmol/l (11.8-42.2), arterial pH 7.34 (7.11-7.51), and bicarbonate 17.5 mmol/l (3.0-25.0). Patients received oral or intravenous fomepizole until blood methanol was undetectable. The median cumulative dose was 1250 mg (500-6000); the median number of twice daily doses was 2 (1-16). Four patients underwent hemodialysis for visual impairment present on admission. Four patients with plasma methanol concentrations of 50 mg/dl or higher and treated without hemodialysis recovered fully. Patients without pretreatment visual disturbances recovered, with no sequelae in any case. There were no deaths. Fomepizole was safe and well tolerated, even in the case of prolonged treatment. Analysis of methanol toxicokinetics in five patients demonstrated that fomepizole was effective in blocking methanol's toxic metabolism.
Conclusions: Fomepizole appears safe and effective in the treatment of methanol-poisoned patients. If our results are confirmed in prospective analyses, hemodialysis may prove unnecessary in patients presenting without visual impairment or severe acidosis.