[Adverse drug reactions and drug interactions in analgesic therapy]

Nowadays multiple pharmacotherapeutic options are available to treat pain. The diverse analgesics differ not only in their mechanism, potency, and efficacy but vary also in adverse drug reactions and drug interactions. Knowledge about the clinically relevant aspects in this field is essential to fit pain therapy to the individual patient. Non-opioids such as acetaminophen are hepatotoxic at high doses or may induce agranolcytosis such as dipyrone. Non-steroidal anti-inflammatory drugs (e.g. diclofenac) have a high risk of toxic effects particularly affecting stomach and kidneys. Especially the reasonable combination with other drugs that were frequently used in pain therapy, such as glucocorticoids, can induce gastrointestinal toxicity and bleeding. Also the use of WHO-II opioids (e.g. tramadol) should be carefully monitored for drug-related problems because of their individual drug metabolism and multiple drug-drug interactions. WHO-II as well as WHO-III opioids (e.g. morphine) provoke constipation, nausea, vomiting, and flush as adverse drug reactions of particular clinical relevance. An appropriate supportive therapy is mandatory, particularly regarding laxatives.