Benzodiazepines are commonly prescribed for anxiety, insomnia, seizures, muscle spasms, and alcohol withdrawal syndrome. Their metabolism primarily involves the CYP450 enzymes, mainly CYP3A4 and CYP2C19, and glucuronidation via UGT enzymes (or only glucuronidation) (267). Accordingly, due to competition for these metabolic pathways, it is likely that when consumed together, ethanol would raise blood concentrations of benzodiazepines. Several studies suggest that ethanol mostly affects the pharmacokinetics of benzodiazepines metabolized by CP450 but not those metabolized by glucuronidation alone. For example, the co-administration of alcohol with triazolam or diazepam increased AUC by 21–27% (268, 269). However, the pharmacokinetics of oxazepam, temazepam, and lorazepam remain largely unaffected (266). Nevertheless, even when pharmacokinetics is unaffected, the concomitant ingestion of alcohol and benzodiazepine can have synergistic sedative effects, suggesting that pharmacodynamic effects are at play (270, 271).
