Effects of ethanol on drug and metabolite pharmacokinetics.

Pharmacokinetic interactions of ethanol with other drugs, including its effects upon drug metabolite disposition, are reviewed in terms of clearance concepts. This approach is particularly useful in understanding the mechanisms of ethanol-drug interactions, i.e. in separating the effects of ethanol upon drug clearance, volume of distribution and plasma protein binding. The application of clearance concepts provides the basis for understanding the qualitative differences in ethanol interactions with low and high hepatic extraction ratio drugs. The effects of short and long term ethanol consumption upon different types of drug metabolism (oxidative, acetylation and glucuronidation) have been considered. Long term ethanol consumption may increase the clearance of a drug by induction of oxidative metabolism whereas short term consumption may decrease the clearance of such a drug. Clearance by N-acetylation appears to be increased in the presence of ethanol, and clearance by conjugation to glucuronic acid is decreased for some drugs by single-dose consumption of ethanol.