Prolonged opioid antagonism with naloxone in chronic renal failure.

Respiratory depression secondary to morphine intoxication occurred in an elderly patient with chronic renal failure (CRF). It was reversed with a continuous infusion of naloxone. Approximately 11 hours after the infusion was discontinued, the patient relapsed into respiratory depression consistent with opioid intoxication. He was rechallenged with a naloxone infusion with resolution of the opioid effects. This case suggests prolonged antagonism of opioid effects inconsistent with naloxone's reported pharmacologic effects. Serum naloxone concentrations measured after the end of the infusion suggest that the drug's pharmacokinetics were significantly altered. Further research is necessary to characterize pharmacokinetic changes that occur in CRF. In the absence of this information, similar patients should be closely monitored for relapse of respiratory depression after naloxone is discontinued.