Switching between morphine and other opioids in palliative care

A NICE Clinical Knowledge Summary on Palliative Cancer Care – pain advises primary care healthcare professionals to:

“Seek specialist advice or consult local guidelines (where available) when selecting the opioid and dose to switch to. This is because experience in primary care is likely to be limited and alternative oral opioids are best initiated by a person with experience in palliative care.”

It is important to consider other strategies if people are suffering from, or are at risk of, side effects, such as:

• non-pharmacological pain relief
• reducing the opioid dose (and possibly adding adjuvant analgesics)
• symptomatic management of the side effect

You may also find information on switching opioids and dose equivalences in national or local  palliative care guidelines, such as the Scottish Palliative Care Guidelines. Or in specialist palliative care reference sources, such as The Palliative Care Formulary (subscription required).

Refer to the Summary of Product Characteristics (SmPC) for the specific opioid you are switching from or to. Most opioid SmPCs include dose equivalence or potency relative to morphine. The SmPC may offer specific prescribing advice for patients previously on morphine or other opioids.

You can find SmPCs for opioid medicines on the eMC or MHRA websites. The information on dose equivalences or switching will usually be in section ‘4.2 Posology and Method of Administration’ or ‘5.1 Pharmacodynamic effects’.

Use our tool (SPS page), along with steps 4 to 6 of our stepped process.

The total daily dose of the current opioid(s), including all long-acting and regular breakthrough doses, must be determined prior to conversion.

Use our tool (SPS page) to identify the approximate potency equivalence, and follow the directions given in the tool to calculate an equivalent morphine or non-morphine opioid dose. If the patient is on multiple opioids, you will need to repeat this step for each opioid before calculating a daily dose.

The usual starting point is to reduce the calculated dose of the new opioid by 25 to 50%.

Consider individual patient factors when deciding whether or not to apply a dose reduction.

High risk patients

A dose reduction is particularly important when:

• using high doses
• people are at increased risk from opioids, such as, elderly or frail patients
• people have not tolerated or have had side effects from the original opioid
• there has been a rapid dose escalation of the original opioid

In these cases, a dose reduction of at least 50% would be recommended.

Low risk patients

Dose reduction may not be necessary in younger patients or for patients taking low doses.

Patients with severe pain

Consider current pain control and severity of pain when deciding whether or not to apply a dose reduction.

Consider:

• asking a colleague to double-check your calculation
• seeking specialist advice

Patients on a regular strong opioid should also have an opioid prescribed ‘as required’ (‘prn’) for breakthrough pain.

Scottish Palliative Care Guidelines suggest an appropriate ‘prn’ dose is typically one-sixth to one-tenth of the regular daily opioid dose.

Refer to the relevant SmPC or BNF for further prescribing advice, including dose intervals and frequency.

NICE Clinical Knowledge Summary on palliative cancer care – pain provides advice on titrating oral morphine doses.

NICE advises frequent review, particularly in the titration to ensure

• pain is adequately controlled
• serious side effects are minimised

Seek specialist advice if, after a few dose adjustments, a good balance between pain control and side effects is not reached.

Make sure patients and family or carers are advised of the signs and symptoms of opioid overdose (drowsiness, shallow breathing, pinpoint pupils). Advise to seek immediate medical help if they occur.