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2437 pages added, reviewed or updated during the last month (last updated: 22/4/2021)


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approximate relative potencies of opioids (opiates) in chronic usage in comparison to morphine

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These conversions are a guide only - seek expert advice and consult local guidelines

  • at high doses, conversion from one opiate to another must always be reviewed cautiously to avoid sudden opiate toxicity.Take particular care if converting high doses of oral opiates to subcutaneous (s.c.) infusions
Analgesic Potency ratio to oral morphine approximate equivalence to 10mg oral morphine on repeat dosing for oral dose approximate equivalence to 10mg oral morphine on repeated dosing for subcutaneous dose/IM dose Duration of action (hours)
Morphine

1

PR (rectal route) 1

10mg 5mg 3-6

Buprenorphine sublingual

- see manufacturer's SPC

60 0.2 mg = 200 micrograms - 6-8
codeine* 1/10 100mg - 3-5
Diamorphine 1 10mg 3mg 3-4
Dihydrocodeine 1/10 100mg - 4-6
Dextropropoxyphene (1) ** 1/10 100mg - 4-6
Tramadol (3) 1/10 100mg - 4-5
Fentanyl see linked item below      
phenazocine (1) 5 2mg - 6-8
Alfentanil    

0.3mg = 300 micrograms

Seek specialist palliative care advice

 

30 minutes IM

60 minutes SC

Hydromorphone   1.3mg 0.6 mg = 600 microgram 3-4 hours
Oxycodone   5mg*** 2.5 4 -6 hours

* determined for parenteral but also appears to apply to oral route

** methadone and dextropropoxyphene have prolonged half lives leading to accumulation when given repeatedly (1)

*** manufacturers guidelines of 2:1 ratio of oxycodone : morphine (note other conversions use a 1.5:1 ratio for oxycodone : morphine) (3)

Reference:

  • (1) West Midlands Palliative Care Physicians (2003). Palliative care - guidelines for the use of drugs in symptom control.
  • (2) West Midlands Palliative Care Physicians (2007). Palliative care - guidelines for the use of drugs in symptom control.
  • (3) West Midlands Palliative Care Physicians (2012). Palliative care - guidelines for the use of drugs in symptom control.

Last reviewed 11/2019

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