Methanol elimination in non-alcoholics: inter- and intraindividual variation

Area of Science:

• Toxicology
• Pharmacokinetics

Background:

• Methanol is a toxic alcohol requiring metabolic clearance.
• Ethanol competitively inhibits alcohol dehydrogenase, the primary enzyme in methanol oxidation.

Purpose of the Study:

• To assess the duration of methanol oxidation inhibition by ethanol.
• To determine methanol elimination kinetics independent of ethanol.
• To evaluate the influence of administration route and alcohol use history on methanol elimination.

Main Methods:

• Five male subjects (25-40 years) received methanol (10 mg/kg) orally and intravenously.
• Ethanol was administered to block methanol oxidation.
• Blood ethanol concentration was monitored to assess inhibition duration.
• Methanol elimination rates and half-lives were calculated.

Main Results:

• Methanol elimination commenced at blood ethanol concentrations of 0.04-0.13 g/kg.
• Methanol elimination constants ranged from 0.406-0.267 h-1, with half-lives of 1.71-2.60 h.
• Including prior data (total n=9), mean elimination constant was 0.298 ± 0.470 h-1 and mean half-life was 2.37 ± 0.357 h.
• No significant differences in elimination kinetics were observed between alcoholics and non-alcoholics, or based on administration route.
• Intraindividual variation in methanol elimination was 3-25%.

Conclusions:

• Ethanol effectively inhibits methanol oxidation, with elimination resuming at specific blood ethanol levels.
• Methanol elimination kinetics are consistent regardless of alcohol use history or route of administration.
• Individual variations in methanol elimination are comparable to those of ethanol elimination.