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CYP2E1 is an enzyme that plays a significant role in the metabolism of alcohol, particularly when there is chronic alcohol consumption. When an individual regularly consumes alcohol, the expression of CYP2E1 is increased, leading to enhanced metabolism of ethanol and also contributing to the metabolism of various other substances. This is particularly notable since CYP2E1 is responsible for the bioactivation of procarcinogenic compounds and the metabolism of numerous drugs.

In chronic drinkers, the increased activity of CYP2E1 can result in higher production of acetaldehyde, a toxic metabolite associated with alcohol consumption. This reaction is part of the reason why individuals who consume alcohol chronically may experience altered drug metabolism and potentiation of drug effects or toxicity.

While other enzymes like alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase are also involved in alcohol metabolism, their activities do not increase to the same extent with chronic use as CYP2E1 does. ADH does metabolize ethanol effectively in the liver, but CYP2E1 becomes the dominant pathway for alcohol metabolism with increased substance use.