Effect of ethanol on the pharmacokinetics of penicillin in the rat

The effect of a single intraperitoneal dose of ethanol (2 g/kg) given 30. min. prior to intravenous administration of benzylpenicillin (20, 40 and 80 mg/kg) was studied in rats. Ethanol pretreated animals showed lower blood and brain tissue levels of penicillin, 15 and 30 min. after the administration of the two lower penicillin doses. This difference was not observed when the penicillin dose was raised to 80 mg/kg. The quotient between brain and serum concentrations was increased 45 min. after the injection of 20 mg/kg of penicillin. Urine collection during the following 2 days showed an increased urine volume during the first 4-hour period in animals pretreated with ethanol. During the same time period they excreted less benzylpenicillin than the controls.