CYP2E1 and alcohol dependence: In addition, since chronic alcoholics have higher basal activity of cytochrome P450 2E1 (CYP2E1), which also accelerates the metabolic rate of volatile anesthetics, the main reason of PONV within the first two hours after surgery moderate- or heavy-drinkers (including alcohol dependence patients) may expect a reduced incidence of PONV post-LSG (56, 57).