Managing Opioids

Key points

  • Opioid analgesics are frequently needed by palliative care patients whose pain is moderate to severe.
  • 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. The Abbey pain scale measures pain in those who can not verbalise. 
  • The aim is to achieve a stable regimen using a long-acting opioid, plus an as-needed short-acting opioid for the patient to use in episodes of incident or breakthrough pain.
  • Morphine, oxycodone or hydromorphone are appropriate opioids to use when initiating treatment.
  • Transdermal patches are an option for stable pain, but due to slow onset and long duration of action are not suitable for initial titration of analgesia 
    • Transdermal buprenorphine is suitable for patients with stable mild pain only. A 20 mcg/hour buprenorphine transdermal patch is equivalent to 30 mg morphine daily orally
    • The lowest dose available (12 mcg/hour) of fentanyl transdermal patch is equivalent to 45 mg morphine daily orally.
  • Some analgesics are inappropriate for use in palliative care, either because of their 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 they have a therapeutic ceiling which may make them less suitable for pain management in a palliative care patient.
  • Pain which is not responding to opioids despite titration should be reassessed, as an opioid switch may be required or the mechanism of the pain may require alternative analgesic strategies, including interventional and/or non-pharmacological approaches. Consult a specialist pain medicine physician, or palliative medicine physician.
  • When switching from an oral opioid to a continuous subcutaneous opioid infusion  a dose conversion table can be helpful to calculate the needed change in medication. See palliAGED Symptoms and Medicines for more on this or use the Faculty of Pain Medicine ANZCA Opioid calculator.
  • Safe Care Victoria has developed guidance on opioid conversion for use by specialist palliative care clinicians. This includes conversion tables. they also provide the following guidance:

Prescribing tips - How to start an opioid

Information on how to initiate and titrate an opioid, and ongoing management 

Titrating an opioid

  • For patients with normal renal and hepatic function, start with a low dose (eg, morphine 20-30mg per day [10-15mg sustained release every 12 hours or 5mg immediate release every 4 hours] with 5mg immediate release rescue doses 1 hourly as needed for breakthrough pain
    • For elderly or frail patients, the starting doses should be halved
    • Advise the patient to seek health care professional advice if 3 consecutive rescue doses have not relieved pain
  • Patients with severe, unstable pain should be reviewed frequently until their pain is controlled. Increase the regular dose until there is adequate relief, taking into account the use of rescue (breakthrough) doses.
  • When stable analgesia is achieved, the opioid requirement over a 24 hour period can be estimated. This should be converted to the equivalent dose of a long-acting preparation, either as a once or twice daily dose depending on the medication used, to provide background analgesia. 
  • Patients should always be prescribed a short-acting rescue opioid medication to use for breakthrough pain alongside the long-acting (background) opioid. 
Preventing opioid side-effects
  • Regular laxatives must be prescribed when starting regular opioids, and the patient should be educated about managing constipation. 
  • 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 the case of nausea and vomiting, bowel obstruction, or difficulty swallowing, use the subcutaneous route.
  • In renal failure - use lower doses and increase the dose interval to at least six hours. Observe carefully for side effects, especially drowsiness, respiratory depression, or myoclonus, until a safe dosage regime is established. Consider opioids which accumulate less in renal failure (hydromorphone, fentanyl).
  • Counsel about driving issues associated with opioid use - especially during the titration phase or after rescue doses have been used.
    See Assessing Fitness to Drive
Ongoing Management
  • Regularly assess and treat opioid side effects (especially constipation).
  • Regularly review the effectiveness of the current analgesics and number of rescue doses required, and adjust the background dosage accordingly.
  • Educating patients about pain management, their opioids and side effects can improve compliance and analgesia.
    See Patient Information - Overcoming Cancer Pain
  • Providing written information or encouraging the use of a pain diary may be very helpful.
    See Patient / Caregiver resource - Pain diary
Incident pain
  • Ensure the patient has access to a breakthrough at an effective dose. 
  • Pre-emptive doses of pain relief can be given half an hour before an activity which usually causes pain may prevent incident pain. Offer this in addition to regular background pain relief. 
    • Use caution in up-titrating analgesics if the reason for extra rescue doses is incident pain, and if rescue doses are taken pre-emptively. If these patients are comfortable at other times, increasing their background dose may not be needed.
  • Patients who are bedbound or in a residential care facility may need a planned rescue dose charted for 'prior to nursing care or procedures'. Ensure it is being given 20-30 mins prior to the care activity.
Switching opioids
  • Reasons why opioid switching may sometimes be needed include:
    • Severe renal failure
    • Adverse effects thought to be due to a particular opioid
    • If a 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 significant inter-individual variation
    See EviQ Opioid Conversion Calculator
    • Different conversion factors may be used in different settings
    • Equianalgesic tables should only serve as a guideline to estimating equivalent opioid doses
    • Clinical judgement should always be used, and doses must be titrated to both pain and side effects
    • Frequent assessment of the patient is required to ensure a safe opioid switch.

From: CareSearch

Assessing fitness to drive - Medical standards for licensing and clinical management guidelines

The national guidelines provide general advice about prescription drugs and driving (see section 4.8.1). The specific advice about opioids is: 

Opioids
There is little direct evidence that opioid analgesics such as hydromorphone, morphine or oxycodone have direct adverse effects on driving behaviour. Cognitive performance is reduced early in treatment, largely due to their sedative effects, but neuroadaptation is rapidly established. This means that patients on a stable dose of an opioid may not have a higher risk of a crash. This includes patients on buprenorphine and methadone for their opioid dependency, providing the dose has been stabilised over some weeks and they are not abusing other impairing drugs. Driving at night may be a problem due to the persistent miotic effects of these drugs reducing peripheral vision.

Ref: Austroads. Assessing Fitness to Drive [Internet]. 2015 [updated 2015; cited 2015 Mar 05].
From: Austroads

 

Last updated 17 February 2020