Basic Principles of Prescribing Analgesia in Patients with Renal Impairment

CONCERN

CONSIDER

Drug Accumulation

Many drugs accumulate in CKD, because of reduced renal excretion and hepatic metabolism

DOSE REDUCTION and INCREASED DOSE INTERVAL

Drug Toxicity

Accumulation may lead to increased toxicity

REGULAR AND FREQUENT REVIEW OF PRESCRIPTIONS

Slower equilibration

Reduced excretion/metabolism leads to slower equilibration

TITRATE DOSES UP/DOWN SLOWLY

Co-morbidities

CKD is associated with multiple comorbidities which affect prescribing

SEEK SPECIALIST/SENIOR ADVICE (TEAM APPROACH)

Specific advice if dialysis or transplant

For patients with CKD Stage 5 including those on dialysis or with a kidney transplant

SEE SPECIFIC GUIDANCE (see tables below)

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The following tables are based on information from the Renal Drug Handbook [1,2].

The doses recommended are safe initial doses and must be titrated up (with careful observation) if pain is not controlled.
Patients who have had surgery are likely to need higher doses (guided by the anaesthetist).
Oxycodone is preferred over morphine in renal failure, and Tramadol is preferred over codeine, although for eGFR less than 30 it is safer to use a small dose of Oxycodone rather than a weak opioid.
Sublingual Buprenorphine 200-400mcg could be used prn for breakthrough pain instead of prn oxycodone
Do NOT use modified release (long-acting) opioids
The eGFR is an estimate and needs to be placed in the clinical context. eGFR will be most inaccurate at extremes of body weight, changes in muscle mass (eg after amputation or paraplegia), or in severe liver disease. In these circumstances it would be more appropriate to calculate GFR using the Cockcroft-Gault formula.
If the creatinine is rising steadily over several days, i.e. there is a progressive deterioration in kidney function, the true GFR will be much lower than the eGFR. For example, oligo-anuric patients with acute kidney injury (AKI) have little GFR and should be dosed as per CKD stage 5 (eGFR less than 10ml/min) whilst the AKI persists.
Give opioids with regular laxatives: many dialysis patients are constipated (haemodialysis reduces stool water content) and peritoneal dialysis works poorly if patients are constipated [3]. Management of constipation MIL: http://ouh.oxnet.nhs.uk/Pharmacy/Mils/MILV8N10.pdf
Caution with NSAIDs: NSAIDs cause reduced renal perfusion and fluid retention. They can be considered in patients on dialysis or in patients with well-functioning kidney transplants. However, their use should be discouraged in people with chronic kidney disease. The renal team would always be happy to advise.
Opioids are appropriate for acute pain - after surgery, infection or trauma - or palliative pain. Opioids generally do not work for chronic pain (pain that lasts longer than 3 months representing a dysfunctional pain system) so should not be continued long-term.
Preservation of venous access: all dialysis patients must have cannulas placed away from potential sites of dialysis venous access (i.e. avoid the wrist, forearms and antecubital fossae; instead use back of the hands, upper arms and lower limbs).

Contact the pain team Useful Contact Details within OUH for more support and advice, or consult The Renal Drug Handbook[1].

Important notes: