Drugs
Conditions
News and resources| Approximate Potency Equivalence with Oral Morphine | |||
|---|---|---|---|
| ORAL | |||
| ANALGESIC | CONVERSION RATIO TO ORAL MORPHINE | RECOMMENDED DOSING FREQUENCY | AVAILABLE FORMULATIONS |
| Codeine | 0.1 | 4-hourly | Tabs, oral soln |
| Dihydrocodeine | 0.1 | 4–6-hourly (or 12-hourly if SR tabs) | Tabs, SR tabs, oral soln |
| Hydromorphone | 5–7.5 | 4-hourly (or 12-hourly if SR caps) | Caps, SR caps |
| Methadone | Variable | 6–8-hourly | Tabs |
| Morphine | 1 | 4-hourly (or 12-hourly if SR prep) | Tabs, SR tabs, SR caps, oral soln, granules for susp |
| Oxycodone | 1.5–2 | 4–6-hourly (or 12-hourly or once daily for SR tabs) | SR tabs, caps, oral soln |
| Pethidine* | 0.1 | 4-hourly | Tabs |
| Tramadol | 0.1 | 4–6-hourly (or 12-hourly or once daily for SR preps) | SR tabs, caps, SR caps, oral soln, orodispersible tabs, sol tabs |
| SUBLINGUAL | |||
| ANALGESIC | CONVERSION RATIO TO ORAL MORPHINE | RECOMMENDED DOSING FREQUENCY | AVAILABLE FORMULATIONS |
| Buprenorphine | 80 | 6–8-hourly or prn | Sublingual tabs |
| SUBCUTANEOUS | |||
| ANALGESIC | CONVERSION RATIO TO ORAL MORPHINE | RECOMMENDED DOSING FREQUENCY | AVAILABLE FORMULATIONS |
| Diamorphine | 3 | 4-hourly | Inj |
| Methadone | Variable | 6–8-hourly | Inj |
| Morphine | 2 | 4-hourly | Inj |
| Oxycodone | 2 | 4-hourly | Inj |
| INTRAMUSCULAR | |||
| ANALGESIC | CONVERSION RATIO TO ORAL MORPHINE | RECOMMENDED DOSING FREQUENCY | AVAILABLE FORMULATIONS |
| Morphine | 2 | 4-hourly | Inj |
| TRANSDERMAL | |||
| Refer to separate table Initiating Treatment with Transdermal Opioids | |||
Multiply by the potency ratio to convert an opioid dose to the equivalent dose of oral morphine
e.g. oral dihydrocodeine 30mg qds = 120mg/day; 120mg x 0.1 = 12mg oral morphine/day
Divide by the potency ratio to convert an oral morphine dose to the equivalent dose of another opioid
e.g. oral morphine 30mg bd = 60mg/day; 60mg/2 = 30mg subcutaneous oxycodone/day
- The conversion ratios in the above table are approximate and are included to provide guidance only.
- Doses will need to be titrated up or down for individual patients.
- When converting at high doses (eg, morphine or equivalent doses of ≥1g/24 hrs) it is recommended to use a lower than calculated dose (eg, ≥50% lower) – prn doses may be used to make up any deficit while titrating to a satisfactory dose of the new opioid.
- These ratios may differ from local formularies or guidance.
Approximate relative potencies taken from Twycross R, Wilcock A, Howard P. Palliative Care Formulary (5th ed). Nottingham: Palliativedrugs.com Lyd, 2014. www.palliativedrugs.com
*Use of pethidine in palliative care is discouraged.
