[Interactions between alcohol and drugs].

Interactions between ethanol and drugs are probably frequent, but few quantitative data are available on the magnitude of the problem. The interactions may be either pharmacodynamic (interactions at the site of drug action) or pharmacokinetic (interactions connected to drug absorption, distribution, metabolism and elimination). The most important interactions occur when ethanol and the drug are present in the organism at the same time. These direct interactions usually lead to supratherapeutic effects and unwanted side-effects, caused mainly by pharmacodynamic but also by pharmacokinetic mechanisms. The most serious interactions are seen with drugs which act on the central nervous system, and with anti-inflammatory drugs, anti-hypertensives and warfarin. Chronic drinking (above 50 g ethanol per day) for months may reduce the response to the drug in sober periods. These indirect interactions (increased tolerance to the drug) are due both to pharmacodynamic and pharmacokinetic mechanisms. Ceasing drinking will be followed by an increase in the efficacy of the drug in question. Long-term intake of ethanol (for years) may cause damage to organs, followed by increased sensitivity to many drugs.