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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.
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