Skip to 0 minutes and 9 secondsOpioids and renal failure is a very important topic. We see quite a bit of this in our practice in palliative care, and it can make our patients really very unwell. Are there any key take home messages that you want to get across to clinicians? It's a very important topic, because our patients are very vulnerable. They have a lot of comorbidities and polypharmacy. When you use strong opiates in renal impairment, there is a very high chance of side effects. So the take home message is very much to have a high index of suspicion of it. I always advise and say, take a baseline renal function.
Skip to 0 minutes and 54 secondsAnd with that renal function, decide on your appropriate opiate, because a lot of the advice when you're prescribing in renal failure is done on expert opinion. So it's like everything. Seek advice if you're struggling, and refer to your local guidelines on depending on that renal function.
Opioids in renal failure
Prescribing opioids in renal failure is informed by knowledge of the pharmacology of the drug, in particular the production and accumulation of any toxic metabolites. The priority is always to ensure patient safety.
In this video Dr Paul Coulter and Dr Victoria Hewitt discuss prescribing and managing opioids in patients with renal failure.
Many factors have to be considered, including the patient’s diagnosis, comorbidities, concurrent prescribing and logistical issues. Furthermore, patients with cancer in renal failure may be very poorly and their disease advanced. These situations are often complex and specialist support may be required.
Steady state in renal impairment
The half life of most opioids is increased in renal impairment due to reduced clearance of the drug and its metabolites from the plasma. It therefore takes longer for the drug to reach steady state. The time between dose titrations may need to be increased and the signs of opioid toxicity may take longer to become clinically evident.
Assessing renal function
Clinical signs and symptoms of chronic kidney disease, such as peripheral oedema, anaemia and loss of appetite, are non-specific and may be attributed to the underlying cancer.
In most clinical settings, renal function is assessed using the estimated glomerular filtration rate (eGFR) as part of the urea and electrolytes blood panel. It is calculated from patient’s serum creatinine, sex, age and race. Remember, the eGFR is an estimation and is notoriously inaccurate at extremes of body weight. The eGFR must never be taken in isolation as the sole determinant of opioid prescribing.
Stages of renal impairment
It is useful in practice to refer to the stage of kidney disease, according to eGFR, when considering opioids.
Stage 1: eGFR >90 ml/min
Normal renal function. Morphine is the strong opioid of choice.
Stage 2: eGFR 60-89 ml/min
Mild renal impairment. Based on clinical experience, morphine is safe to prescribe provided the dose is carefully titrated in small increments and the patient is monitored. If the patient experiences opioid toxicity, conversion to oxycodone is appropriate.
Stage 3a: eGFR 45-59 ml/min
Mild to moderate renal impairment. The same advice for Stage 2 applies. However, if the renal function is rapidly declining a pre-emptive opioid change is appropriate.
Stage 3b: eGFR 30-44 ml/min
Moderate to severe renal impairment. The same advice Stage 3a applies. As the potential for toxic metabolites increases (even with oxycodone), consider conversion to immediate release formulations and increasing dosing intervals. Careful monitoring is required and the patient should be converted to alfentanil at first signs of toxicity.
Stage 4: eGFR 15-29 ml/min
Severe renal impairment. The patient should be prescribed an opioid which is safe in renal failure. Alfentanil is the opioid of choice in this situation, accepting it is only available in injection form. For practical reasons, oral IR oxycodone for rescue analgesia may be prescribed under caution and the patient monitored closely. Oxycodone MR may also be continued if there are no signs of opioid toxicity. Fentanyl patches should continue if the pain is stable and a dose reduction considered. Conversion from another opioid to a fentanyl patch is not recommended as cases of respiratory depression have been reported. If a patient becomes toxic with a transdermal opioid patch in situ it must be removed immediately and converted to alfentanil.
Stage 5: eGFR <15 ml/min
End stage renal disease. Alfentanil is the opioid of choice. It has a very short duration of action so must be given as a continuous subcutaneous infusion to achieve background analgesia with alfentanil injections for break through pain. Specialist advice may be required.
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