Alcohol Metabolism

Ethanol (also called alcohol or ethyl alcohol) is the most commonly abused psychoactive drug. Its metabolism is the cause of a vast array of pathologic manifestations which affects almost all organs. The goal of this article is to describe and update the pathways responsible for the metabolism of ethanol and understand the factors which regulate its metabolism. Most alcohol is oxidized in the liver and general principles and overall mechanisms for alcohol oxidation will be summarized including the enzymatic pathways responsible for this metabolism. Rate-limiting steps in the overall metabolism of ethanol, including the activity of alcohol dehydrogenase isoforms, and the necessity to reoxidize NADH by substrate shuttle pathways and the mitochondrial respiratory chain will be discussed. Other ethanol-metabolizing pathways such as catalase and the microsomal ethanol-oxidizing system/CYP2E1 system will be characterized. The metabolism and role of acetaldehyde in the toxic actions of alcohol and ethanol drinking behavior will be discussed. Despite much knowledge of alcohol pharmacokinetics and metabolism, numerous questions which remain for further evaluation are presented and future research directions are suggested.