From the Guidelines
The morphine milligram equivalent (MME) for methadone 22.5mg is approximately 225 MME. Methadone has a variable conversion factor that increases with higher doses, typically ranging from 3:1 to 10:1 depending on the dose, as noted in the CDC clinical practice guideline for prescribing opioids for pain - United States, 2022 1. For doses between 20-40mg, a conversion factor of 10:1 is commonly used, meaning each milligram of methadone equals 10 milligrams of morphine equivalent. Therefore, 22.5mg of methadone multiplied by the conversion factor of 10 equals 225 MME. It's essential to consider that methadone has a complex pharmacokinetic profile with a long and variable half-life, which makes it more potent than its MME might suggest, as highlighted in the guideline 1. This is why methadone requires careful dosing, monitoring, and should only be prescribed by clinicians experienced with its use, taking into account its unique risk profile, including the risk of QT prolongation and overdose, especially in patients with renal or hepatic dysfunction 1. Patients on this dose of methadone should be monitored closely for side effects such as respiratory depression, QT prolongation, and sedation. Key considerations for prescribing methadone include:
- Its potential for increased risk of overdose, particularly in the first two weeks of therapy 1
- The need for careful patient selection, education, and monitoring 1
- The importance of using predictable pharmacokinetics and pharmacodynamics to minimize unintentional overdose risk 1
From the Research
Methadone Equivalent Dosage
To determine the Morphine Milligram Equivalent (MME) for methadone 22.5mg, we need to consider the conversion factors between different opioids. However, the provided studies do not directly address the conversion of methadone to MME.
Available Information
- The studies provided focus on the management of pain with methadone 2, evidence-based treatment for opioid disorders 3, the effectiveness of naltrexone in preventing recurrence of methadone poisoning in opioid-naive children 4, treatment of opioid overdose 5, and the contributions of fentanyls to the rise in opioid overdose deaths 6.
- None of the studies provide a direct conversion factor from methadone to MME.
Limitations
- Without specific conversion factors or studies directly addressing the MME for methadone 22.5mg, it is not possible to provide an accurate calculation.
- The available studies do not provide sufficient information to determine the MME for the given dose of methadone.