Alcohol and opioids: possible interactions of clinical importance.

The multiple areas of possible opioid-ethanol interaction are reviewed. Both ethanol and the major opioids are metabolized in part by the hepatic MEOS system. Both will augment MEOS activity governing their own rates of disposal. However produced, faster drug disposal rates of ethanol and the opioids may account for some clinical findings. Yet, when both drugs are used together, slower disposal rates and possibly higher toxicities may arise. Ethanol may modify some opiate receptors, and possibly change the brain tissue endogenous opiate peptide levels in some loci. It also may modify the effects of opioids in the animal. The functional and clinical significance of these observations remain unclear. Opioids may affect the drinking behavior of animals under some circumstances. Antagonists may affect the depth of alcohol intoxication, although the evidence is not conclusive. Usually significant differences from controls were small or lacking in human studies. Mixed opioid and alcohol abusers did poorly in standard alcohol abstinence treatment, compared to matched alcoholics without opiate abuse histories. Opiate addicts in general and on methadone maintenance treatment appear to have unusually high rates of recognized alcoholism. Methadone treatment per se was not documented to produce increasing rates of alcohol consumption or to cause large numbers of alcohol related problems in prospective studies. The relationship between alcohol and opioid abuse appears to be complex and multifactorial.