- Opioids are used in a wide variety of clinical settings and are well established for the treatment of both acute and chronic pain. Renal impairment (RI) not only alters the clearance of the parent compound but also affects the accumulation of its metabolites. Elimination may be prolonged.
- Absolute recommendations on reductions of opioid doses are difficult as a clear relationship between renal function and removal of opioid metabolites has yet to be identified.
- Recommendations for adjustment of doses are based on pharmacokinetic studies and clinical experience.
- Dihydrocodeine and pethidine should be avoided in RI; codeine should be used cautiously in mild to moderate RI and avoided in severe RI, although it is used in practice in some renal units.
- Tramadol, diamorphine, morphine, hydromorphone, methadone and oxycodone should be used with caution in RI. Patients should be started on low doses and/or with extended dosage intervals. The dose should be slowly titrated upwards depending on response and any observed adverse effects.
- Fentanyl, alfentanil and buprenorphine exhibit the safest pharmacological/pharmacokinetic profile in RI. Whilst there is limited evidence for the use of these drugs in RI, on the basis of their pharmacokinetics they can be used cautiously but the risk of an unfamiliar opioid should be considered. Dose titration of fentanyl and alfentanil should be supervised by a specialist familiar with their use as they are highly potent opioids. Monitoring for signs of toxicity is required.
A table of dosage recommendations for opioids in RI is included.