Interaction of paracetamol in chronic alcoholic patients. Importance for odontologists.

For social, cultural and historical motives alcohol (ethanol or isopenthanol) is considered to be just a beverage rather than a liquor. However, from a pharmatherapeutic point of view alcohol is a depressor of the central nervous system. The effects of alcohol consumption can range from raised loquacity to drunkenness, loss of consciousness and death as a result of insufficient respiration. Probably the most frequent pharmacological interaction is the combination of alcohol with other depressors of the central nervous system which increases the depression even further. Some medicaments which more frequently produce an interaction are antihistamines, analgesics, antidepressants and medicaments for coughs, common cold and influenza. Paracetamol or acetaminophen is an analgesic medicament similar to acetylsalicylic acid lacking anticoagulatory properties and gastric irritation. However, its major drawback is hepatic toxicity as a result of a toxic metabolite produced in the liver by cytochrome P-450, principally cytochrome CYP2E1, which is detoxified under normal conditions by hepatic glutathione. Ethanol is also detoxified by CYP2E1, which is an inducer of ethanol such that chronic ingestion increases the level of this enzyme. When the ingestion of alcohol is stopped, CYP2E1 is greatly increased and only metabolises the paracetamol giving rise to high quantities of hepatotoxic metabolites so that the hepatic glutathione is unable to detoxify resulting in irreversible hepatic damage. Therefore for odontologists it is important that in chronic alcoholic patients the consumption of alcohol should not be suspended on prescribing paracetamol.