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Converts between different types and routes of opiates. This calculator is for double-checking opiate conversion, and should NOT be used as the primary means for ordering. Select the opiate and route that you wish to convert from. Input the total daily dose in milligrams of the opiate you are converting from.
Dose-dependent conversions: The conversion ratio of certain opioids can be dependent on the dose of the original opioid. In the case of converting morphine to methadone, methadone has a relative potency of 4:1 at lower morphine doses, but becomes much more potent (12:1) in patients converting from very high morphine doses. 5 , 7
Purpose of Oral Morphine Equivalence (OME) calculations. OME calculations help identify opioid tolerance in individual patients. The FDA defines an opioid-tolerant patient as receiving for 1 week or longer at least 60 mg oral morphine/day or an equianalgesic dose of another opioid.
The calculator provides conversions from one opioid to another and/or from one route of administration to another, to be used as a guide only. It is not tailored to any specific pain syndrome or for utilisation by specific healthcare professionals.
Where dose equivalence is expressed as a range, use the value that produces the lowest equivalent dose and titrate as necessary. Particular care is required when dealing with high doses of opiates.
For example, if your reduced IV morphine dose was 50mg, the equivalent IV hydromorphone dose is 10mg. Divide this number by the bioavailability of the new drug to get a bigger number, that being the oral 24 hour dose of the new drug.
Use the conversion chart to work out the equivalent doses of different opioid drugs by different routes. The formula to work out the dose is under each drug name. Examples are given as a guide. Renal failure/impairment GFR<30mL/min: Morphine/Diamorphine metabolites accumulate and should be avoided. Fentanyl patch if pain is stable.
