These conversions are a guide only (1,2,3,4) - seek expert advice and consult local guidelines
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 |
Buprenorphinesublingual - 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)
NHS tool to calculate estimated dose equivalences of oral morphine to other oral opioids (4)
Reference:
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