CAUTION: This calculator is intended for calculating the Morphine Equivalent Dose (MED) dose for a patient taking one or more opioid medications. It should not be used to determine doses when converting a patient from one opioid to another. Equianalgesic dose ratios are only approximations and do not account for genetic factors, incomplete cross-tolerance, and pharmacokinetics.
Instructions: Fill in the mg per day for the patient’s opioid medications. The daily morphine equivalent dose is calculated automatically.
Opioid:
mg per day:
Morphine Equivalent Dose:
Codeine
Fentanyl transdermal (in mcg/hr)
Hydrocodone
Hydromorphone
Methadone
Methadone has been associated with disproportionate numbers of overdose deaths relative to the frequency with which it is prescribed for chronic pain, due in part to its long and variable half-life. In addition, methadone is associated with cardiac arrhythmias along with QT prolongation on the electrocardiogram. Methadone should not be the first choice for an ER/LA opioid. Increasing methadone doses over 30 mg/day is not recommended.
Conversion Factor
There is limited evidence and no consensus on the conversion factors to use for methadone. We use a 3 to 1 ratio that is consistent with CMS, the State of Oregon PDMP, and research studies by Von Korff (Clin J Pain 2008;24:521-7) and Krebs (Pain 2011;152:1789-95). The WA State AMDG calculator uses higher conversion ratios that increase at higher doses (0-20 mg 4:1 ratio, 21-40 mg 8:1 ratio, 41-50 mg 10:1, over 51 mg 12:1 ratio)
For the dose entered, these two conversion ratios are:
mg (this calculator)
mg (AMDG calculator)
Morphine
Oxycodone
Oxymorphone
Tapentadol
Taptentadol ER: maximum daily dose of 500 mg (250 mg PO twice daily). Consider lower doses in geriatric patients.
Tapentadol IR: maximum of 700 mg on day 1 and 600 mg per day thereafter.
Tramadol
Tramadol ER: Maximum: 300 mg PO once daily. Dose no more frequently than every 24 hours. Consider lower doses in geriatric patients over 65 years of age.
Tramadol IR: Maximum (age up to 75 years): 400 mg/day; Maximum (75 years and older): 300 mg/day.
Use caution when prescribing opioids at any dosage
Reassess benefits and harms when increasing dosage to ≥50 mg MED/day and decrease dose if benefits do not outweigh harms.
Avoid increasing dosage to ≥90 MED/day or carefully justify a decision to titrate dosage to ≥90 MED/day
Considering offering naloxone when factors that increase risk for opioid overdose, such as history of overdose, history of substance use disorder, higher opioid dosages (≥50 MME/day), or concurrent benzodiazepine use, are present
Concurrent use of opioid pain medication and benzodiazepines is likely to put patients at greater risk for potentially fatal overdose, as both medications can cause central nervous system depression and decreased respiratory drive. (CDC guideline recommendation #11)
Buprenorphine is not included in the calculator because it is a partial agonist and morphine equivalent doses are uncertain. Please refer to the label for dosing parameters.