The elimination kinetics of methanol and the influence of ethanol.

Four male subjects aged between 20 and 29 years were given intravenous injections of methanol at a dosage of 10 mg per kg body weight, once without prior administration of ethanol, and once after oral ingestion of 0.3 g ethanol per kg body weight. The serum methanol concentration was monitored over the next 5 h (after methanol administration alone) and 6-7 h (after methanol administration following ethanol ingestion). The elimination of methanol administered alone was found to follow first-order kinetics with a rate constant for the elimination phase of 0.475-0.259 h-1, corresponding to an elimination half-life of 1.8-3.0 h. When ethanol was also administered methanol oxidation was found to be completely blocked until the blood ethanol concentration had fallen to 0.2 g/kg. When the ethanol concentration had dropped to zero, methanol elimination followed exactly the same course as that observed in the experiment without prior administration of ethanol (k: 0.378-0.231 h-1; t1/2: 1.5-2.7 h).