Patient selection: patient with cirrhosis treated with morphine
Metabolites: morphine-3; morphine-6
Effect of cirrhosis on morphine metabolism include:
(1) increased half-life (decreased metabolism in the liver)
(2) drug accumulation with repeat dosing
(3) increased bioavailability (decreased first pass metabolism due to portal shunting)
These effects may not be seen in early or mild cirrhosis, but should be more common in Child-Pugh class C cirrhosis.
Recommendations:
(1) monitor blood levels of morphine and its metabolites
(2) monitor the patient for signs of morphine toxicity
(3) reduce the dose of morphine or increase the dosing interval
(4) use another analgesic not impacted by cirrhosis
(5) monitor serum albumin
(6) monitor for evidence of renal failure, which may impact drug elimination
