Inhibition of the rate of 14CO2 production from [14C]ethanol in rats given beta-lactam antibiotics with disulfiram-like effects.

An animal model has been developed to investigate the potentials of various beta-lactam antibiotics for inducing (or producing) disulfiram-like effects. The method, which measures the rate of 14CO2 production in rats after [14C]ethanol administration, is simple to operate and sensitive. On the basis of available clinical information the model appears to be highly predictive for the likely incidence of disulfiram-like side effects in humans. Rats were pretreated intravenously with beta-lactam antibiotics (420 or 500 mg/kg-1) 18 h before ethanol administration or with N-methyl tetrazole thiol (NMTT; 1-methyl-5-mercaptotetrazole) at 96 mg kg-1, 6 h before ethanol administration. The rate of 14CO2 production was decreased to 70 to 80% of control levels by NMTT and the NMTT-containing beta-lactam antibiotics moxalactam, cefamandole, and cefoperazone. Cefotaxime, cephalothin, and cefuroxime which do not contain the NMTT side chain had no significant effect on 14CO2 production. Oral administration of moxalactam (500 mg kg-1) and NMTT (96 mg kg-1) 18 and 6 h, respectively, before ethanol administration significantly decreased 14CO2 production. Intravenous administration of moxalactam (500 mg kg-1) to rats with cannulated bile ducts 18 h before ethanol administration had no statistically significant effect on 14CO2 production, although the rate of 14CO2 production was decreased to 89% of the control level. The effect of dose level and dose interval was also investigated by using moxalactam. The results obtained support the hypothesis that disulfiram-like side effects associated with beta-lactam antibiotics are mediated by NMTT which is released and reabsorbed from the gut after biliary elimination of the parent beta-lactam antibiotic. The time course of inhibition of ethanol metabolism by moxalactam appears to differ from that of disulfiram.