What alternative to subcutaneous morphine (opioid analgesic) is recommended for a patient with impaired renal function requiring pain relief, according to UK guidelines?

From the Guidelines

For a patient with poor renal function requiring an alternative to subcutaneous morphine, fentanyl would be the most appropriate opioid choice in the UK, as it is minimally affected by renal impairment and has no active metabolites that accumulate in renal failure. This recommendation is based on the most recent and highest quality study available, which emphasizes the importance of choosing an opioid that is safe for patients with renal impairment 1. Fentanyl is primarily metabolized in the liver, making it a suitable option for patients with impaired renal function.

Some key points to consider when using fentanyl in patients with renal impairment include:

• Starting with a low dose, such as fentanyl 12.5-25 micrograms subcutaneously as needed every 1-2 hours, titrating carefully according to response
• Alternatively, considering a fentanyl patch starting at 12 micrograms/hour for more stable pain
• Close monitoring is essential when initiating these medications, watching for signs of opioid toxicity such as excessive sedation or respiratory depression
• Dose reductions of 25-50% compared to normal renal function are typically recommended initially

Other options, such as buprenorphine, may also be considered, particularly for patients with stable opioid requirements, as it is mainly excreted in the stool and does not require dose reduction in renal impairment 1. However, the dose conversion from other opioids to buprenorphine can be complex, and palliative care advice is recommended. Methadone is another alternative, but its use requires caution due to marked interindividual differences in its plasma half-life and duration of action 1.

It is essential to avoid opioids that produce active metabolites that accumulate in renal impairment, such as morphine, as they can cause prolonged sedation, confusion, and respiratory depression 1.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

Alternative to Subcutaneous Morphine for Patients with Impaired Renal Function

According to UK guidelines, the following alternatives to subcutaneous morphine are recommended for patients with impaired renal function requiring pain relief:

• Fentanyl, alfentanil, and buprenorphine are considered safe options for patients with renal impairment 2, 3, 4, 5
• Methadone and oxycodone may be used with caution and in reduced doses 3, 6
• Hydromorphone can be used as an alternative to morphine, but with reduced dose 3, 6
• Tramadol is the least problematic of the Step 2 analgesics, but dose reduction and increased dosing interval are required, and caution should be exercised 2
• Acetaminophen (paracetamol) is recommended at Step 1 of the World Health Organization ladder 2

Opioids to Avoid in Patients with Impaired Renal Function

The following opioids should be avoided or used with caution in patients with impaired renal function:

• Morphine and diamorphine are not recommended due to the accumulation of potentially toxic metabolites 2, 4
• Codeine and pethidine should be avoided entirely 3, 5
• NSAIDs may be used in CKD and ESKD for short durations with careful monitoring 6