Metabolic and pharmacodynamic tolerance to ethanol in rats.

The development of tolerance to ethanol was studied in rats fed nutritionally adequate liquid diets containing ethanol or sucrose for up to 5 weeks. Tolerance was shown to be due to both metabolic and pharmacodynamic factors. Tolerance began to develop after 3 days of ethanol intake, reached a plateau by 16 days and persisted for up to 22 days after stopping the ethanol intake. The rate of onset and decay of both components of tolerance was similar.