[Opioids during anesthesia in liver and renal failure].

The pharmacokinetics of opioids are impaired in patients with liver and renal failure. Fentanyl, sufentanil, and alfentanil are metabolized in the liver. The extrahepatic metabolism by renal enzymes is gaining more importance in patients with severe liver disease. Pharmacokinetic effects of single doses of fentanyl and sufentanil are not affected in liver and renal failure; however, continuous infusion of fentanyl may result in accumulation and prolonged opioid effects. Plasma clearance and elimination of alfentanil are reduced in patients with liver failure and its clinical use can therefore not be recommended. A reduction in alfentanil dosing is not necessary in patients with renal failure. Remifentanil is the opioid of choice in patients with liver and renal failure. The clearance of morphine is reduced in liver failure. In renal failure an accumulation of morphine metabolites has been demonstrated, and thus, application of morphine is not recommended in patients with liver and renal failure. A reduction in piritramide dosing is necessary in patients with liver failure.