These drugs have a wide margin of safety when taken alone. However, the risk of lethal consequences can be significantly enhanced when benzodiazepines are taken in combination with large doses of alcohol, barbiturates or other CNS depressants. Benzodiazepines are absorbed relatively rapidly and almost completely from the gastrointestinal tract. Clinical effects usually begins within 1 hour and peak within 1-4 hours after ingestion. Although the number of people who use benzodiazepines as their sole drug of abuse is low, ethanol and benzodiazepines are commonly used concurrently.
Alcoholic patients use benzodiazepines more commonly than the general population.
Ethanol, in the form of one cocktail, slows the rate of absorption of diazepam but has no effect on overall completeness of absorption. Benzodiazepines are metabolized in the liver by oxidation, conjugation or nitroreduction reactions. Metabolites have longer elimination half-lives and are less likely to be cleared effectively in patients with hepatocellular disease. Alcohol and other sedatives enhance the CNS depression caused by benzodiazepines in an additive manner. Psychological dependence is common.