Overview of switching opioids in palliative care
When switching opioids, ensure patients have adequate immediate-release opioid therapy available to manage any breakthrough symptoms.
Switching opioids involves determining equianalgesic opioid doses. Calculating equianalgesic doses is an inexact science. Equivalent opioid doses vary across resources; they are based on average equianalgesic doses calculated from pooled adult samples. Exercise caution when using equianalgesic doses because there are significant pharmacokinetic and pharmacodynamic variations between individuals; review patients frequently.
Confirm manual calculations of opioid doses by using a digital conversion calculator1 (eg eviQ calculator or the Australian and New Zealand College of Anaesthetists (ANZCA) Faculty of Pain Medicine opioid calculator and application), or check them with a palliative care specialist, pharmacist or colleague.
Not all opioids are easily converted to an equianalgesic dose.
- When changing from morphine to methadone, the conversion factor varies considerably depending on the morphine dose. Methadone should only be prescribed by practitioners experienced in its use.
- Tapentadol and tramadol have reduced mu-receptor agonism compared to other opioids and the analgesic effect is partly due to noradrenaline or serotonin reuptake inhibition. If changing from an opioid to tapentadol or tramadol, take an individualised approach and consider cross-tapering to avoid opioid withdrawal
- Transmucosal fentanyl formulations (eg lozenges, sublingual or orally disintegrating tablets) are not interchangeable because they have different pharmacokinetics; start the new formulation at its usual starting dose (see product information) and increase as appropriate.
- Switching to or from a transdermal fentanyl formulation requires caution—for discussion, see Considerations when switching routes of administration or formulations of opioids in palliative care.
- When switching from an oxycodone+naloxone formulation to another opioid formulation (including oxycodone as a single drug):
- at high doses, naloxone may be systemically absorbed—consider starting with a lower equivalent dose of the new opioid (eg 50 to 75% of the approximate equianalgesic dose), and closely monitor the patient for adverse effects or toxicity
- in patients with liver impairment, the bioavailability of oral naloxone is increased thus reducing the efficacy of opioids given concurrently. When switching to another opioid formulation, start with a lower equivalent dose of the new opioid (eg 50% of the approximate equianalgesic dose), and closely monitor the patient for adverse effects or toxicity.
After switching opioids, adjust the regular opioid dose according to patient response, and monitor for adverse effects. Advice on monitoring and adjusting regular opioid therapy is available in these guidelines for:
- pain—see Regular oral opioids for background pain in palliative care, Increasing the dose of regular opioid therapy in palliative care and Monitoring analgesic therapy in palliative care
- breathlessness—see Regular opioid therapy for chronic breathlessness in palliative care.
For information on opioids used in palliative care, see Principles of opioid use in palliative care.
|
Opioid [NB2] |
Approximate equianalgesic doses |
|---|---|
|
Oral | |
|
morphine (mg/day) |
30 mg |
|
codeine (mg/day) [NB3] |
230 mg |
|
hydromorphone (mg/day) [NB4] |
6 mg |
|
oxycodone (mg/day) |
20 mg |
|
tapentadol (mg/day) [NB5] |
100 mg |
|
tramadol (mg/day) [NB5] |
150 mg |
|
Parenteral [NB6] | |
|
buprenorphine (micrograms/day) |
300 micrograms |
|
fentanyl (micrograms/day) |
150 micrograms |
|
hydromorphone (mg/day) [NB4] |
2 mg |
|
morphine (mg/day) |
10 mg |
|
oxycodone (mg/day) |
10 mg |
|
tramadol (mg/day) |
100 mg |
|
Sublingual | |
|
buprenorphine (micrograms/day) |
750 micrograms |
|
Transdermal [NB7] | |
|
buprenorphine (micrograms/hr) |
15 micrograms per hour |
|
fentanyl (micrograms/hr) |
10 micrograms per hour |
|
Note:
NB1: This table provides a summary of approximate equianalgesic opioid doses. An opioid conversion calculator available from eviQ, and an opioid calculator and application from the Australian and New Zealand College of Anaesthetists (ANZCA) Faculty of Pain Medicine are available to help with dose calculations. NB2: Equianalgesic doses of methadone are not included in this table because, when changing from methadone to morphine, the conversion factor varies considerably depending on the morphine dose. Methadone should only be prescribed by practitioners experienced in its use. NB3: Codeine has no role in symptom management. Its inclusion in this table is to assist with changing from codeine to an opioid that is suitable for symptom management. NB4: Hydromorphone should only be prescribed by practitioners experienced in its use. NB5: Doses of tapentadol or tramadol are not easily converted to equianalgesic opioid doses. Tapentadol and tramadol have reduced mu-receptor agonism compared to other opioids and the analgesic effect is partly due to noradrenaline or serotonin reuptake inhibition. If changing from an opioid to tapentadol or tramadol, take an individualised approach and consider cross-tapering to avoid opioid withdrawal. NB6: Administration by different routes results in different times to peak concentration. When using the intravenous route, start with lower doses and titrate to effect. NB7: Transdermal doses are expressed per hour, in line with available formulations. Source: The Pain and Analgesia guidelines, based on the Faculty of Pain Medicine, Australian and New Zealand College of Anaesthetists (ANZCA). Opioid dose equivalence–Calculation of oral morphine equivalent daily dose (oMEDD). Melbourne: ANZCA; 2019. URL | |
|
Original dose |
|
A patient with frequent breakthrough pain when taking morphine modified-release 100 mg orally, twice daily has the dose increased to 120 mg twice daily. The pain is managed, but the patient now has significant nausea despite taking adequate regular doses of antiemetics. A change to a different opioid, such as oxycodone, may reduce adverse effects. |
|
Calculation [NB1] |
|
morphine modified-release 120 mg twice daily gives a total of morphine 240 mg in 24 hours morphine 240 mg in 24 hours is approximately equivalent to oxycodone 160 mg in 24 hours (see Approximate equianalgesic doses of opioids in palliative care for approximate equianalgesic doses of different opioids)
75% of the calculated 24-hour oxycodone dose is oxycodone 120 mg in 24 hours [NB2] use half of this oxycodone amount for the regular twice daily dose use one-twelfth to one-sixth of the 24-hour oxycodone amount for a breakthrough pain dose |
|
New dose |
|
For the regular oxycodone modified-release dose oxycodone modified-release 60 mg orally, twice daily, starting 12 hours after the last twice-daily morphine dose was taken [NB3] For the breakthrough oxycodone immediate-release dose oxycodone immediate-release 10 to 20 mg orally, 1-hourly as required |
|
Note:
NB1: Confirm manual calculations using a digital opioid conversion calculator (eg eviQ calculator or the Australian and New Zealand College of Anaesthetists (ANZCA) Faculty of Pain Medicine opioid calculator and application), or check them with a palliative care specialist, pharmacist or colleague. Seek expert advice when switching opioids in patients taking more than 100 mg oral morphine (or equivalent) in 24 hours. NB2: Start with 75% of the calculated equianalgesic dose because the patient had good pain control, and the change is being made because of adverse effects from morphine. NB3: See Suggestions for how to time the switch between opioid formulations and/or routes of administration in palliative care for how to time the switch between different opioid formulations and routes of administration.
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