Der Schmerz
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In patients with renal or hepatic failure, the pharmacokinetics of opioids may be affected in several ways, leading to the necessity to correct the dose. The liver is the major site for biotransformation of most opioids. The major metabolic pathway is oxidation. ⋯ On the other hand, the analgesic activity of codeine and tilidine depends on transformation into the active metabolites, morphine and nortilidine. In the case of reduced metabolism in chronic liver disease, the analgesic action of these drugs may be compromised. Lastly, the disposition of a few opioids, such as fentanyl, sufentanil, and remifentanil, appears to be unaffected in liver disease.