When to start an opioid
Opioid analgesics are frequently needed by palliative care patients whose pain does not respond to simple analgesics, weak opioids, adequate doses of adjuvants, and other measures. Adjuvants should be continued.
Persistent pain should be treated promptly. A high index of suspicion about the presence of pain is needed in agitated patients who are unable to verbalise their experiences, due to dementia, communication problems or reduced level of consciousness.
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TIP - There is now evidence supporting the use of opioids for dyspnoea as safe and effective, both for patients with lung malignancies and those with other primary lung diseases, including COPD. |
About specific opioids
Morphine, oxycodone or hydromorphone are appropriate strong opioids to start. Fentanyl transdermal patches are an option for stable pain, but they are long-acting and take 12 – 24 hours to full effect, and are therefore often not suitable for initiating analgesia.
Some analgesics are less suitable for use in palliative care, either because of their inappropriate pharmacokinetics, potential for drug interactions, or other problems. These include:
- Pethidine
- Dextropropoxyphene (Capadex, Digesic, Paradex, Doloxene)
- Dextromoramide
- Pentazocine.
Tramadol and buprenorphine are commonly used in primary care, however their place in long-term palliative care prescribing is still being defined.
Initiation and titration
Basic principles for opioid prescribing have been developed by World Health Organization (WHO Pain Ladder) and these continue to be fundamental:
- By mouth
- By the clock
- By the ladder
- Individual dose titration
- Use adjuvant drugs
- Attention to detail.
Patients who are opioid naïve should have their opioid doses titrated carefully. A safe practice is to start with short-acting opioids prescribed at four-hourly intervals, with extra as-needed (breakthrough) doses of the same amount if pain is still not controlled. Starting doses recommended by the Therapeutic Guidelines are 5 – 10 mg po every four hours, or 2 – 5mg po every four hours in frail patients.
Patients with severe, unstable pain should be reviewed frequently until their pain is controlled. Increase the regular dose until there is adequate relief through the four hour period, taking into account the use of as-needed (breakthrough) doses.
When stable analgesia is achieved, the opioid requirement over a 24 hour period can be estimated. This should be converted to a long-acting preparation, usually divided into a twice daily dose, to provide background analgesia. Patients should also be prescribed a short-acting “breakthrough” opioid medication to use for exacerbations of pain.
Laxatives must be prescribed when initiating regular opioids. Nausea and drowsiness can be a problem at first, and antiemetics may initially be required, but most patients rapidly become tolerant to these symptoms.
In renal failure - use lower doses and increase the dose interval to at least six hours. Observe carefully for side effects, especially drowsiness and respiratory depression, until a safe dosage regime is established.
Counsel about driving issues associated with opioid use – especially during the titration phase.
Ongoing management
Good pain management involves:
- Regularly assessing and treating opioid side effects (especially constipation)
- Regularly reviewing the effectiveness of the current analgesics and number of breakthrough doses required, and adjusting the background dosage accordingly
- Educating patients about pain management, their opioids and side effects which can improve compliance and analgesia. Providing written information may be very helpful.
Incident pain
Use caution in titrating analgesics when the reason for extra as-needed doses is incident pain - ie pain predictably associated with physical activity of some kind. These patients may be comfortable at other times, and increasing their background dose may not be needed.
One-off doses of pain relief given half an hour before an activity which usually causes pain may prevent it. Use this in addition to regular background pain relief.
Switching opioids
Reasons why opioid switching may sometimes be needed include:
- Severe renal failure
- Adverse effects thought to be due to a particular opioid
- Change in route of administration is required
- Problems with large volumes needing to be given orally or subcutaneously.
Published guidelines for opioid conversion are based on estimates, often from single dose studies rather than chronic use, and there is also inter-individual variation. Different conversion factors may be favoured by different clinicians. A recent systematic review by Shaheen,Walshe et al in 2009 points out that equianalgesic tables should only serve as a general guideline to estimate equivalent opioid doses. Clinical judgement should always be used, and doses must be titrated to pain and side effects.
Click here to go to an online opioid conversion calculator from Palliative Medicine Handbook.
Opioid non-responsive pain
Pain which is not responding to opioids should be reassessed, as the mechanism of the pain may suggest alternative analgesic strategies, including non-pharmacological approaches.
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This page was created on 26 May 2009 and is due for review in May 2011.
Last updated 5 February 2010