From the Guidelines
The methadone to Dilaudid (hydromorphone) conversion ratio is approximately 1:5, meaning 1 mg of hydromorphone is equivalent to about 0.2 mg of methadone, based on the morphine milligram equivalent (MME) conversion factors. This is derived from the MME conversion factors provided in the CDC clinical practice guideline for prescribing opioids for pain - United States, 2022 1, where hydromorphone has a conversion factor of 5.0 and methadone has a conversion factor of 4.7.
When converting between these medications, it's crucial to consider the complexities and variabilities involved, particularly with methadone's unique pharmacology. Methadone has a long and variable half-life, and its peak respiratory depressant effect occurs later and lasts longer than its peak analgesic effect 1. Therefore, a conservative approach is recommended, using equianalgesic tables as a starting point and reducing initial doses by 25-50% from the calculated equianalgesic dose to prevent overdose while maintaining pain control.
Key considerations in this conversion include:
- Methadone's long half-life (15-60 hours) and cumulative effects, which necessitate careful monitoring and dose adjustments 1.
- The risk of QT prolongation associated with methadone use, requiring careful patient selection and monitoring 1.
- Incomplete cross-tolerance between opioids, which demands a cautious approach to avoid overdose 1.
- The need for frequent assessments, particularly in the first week of conversion, as methadone's full effect may take 5-7 days to stabilize 1.
Given these complexities, methadone conversions should ideally be managed by pain specialists or physicians experienced with opioid rotation, ensuring that patients receive the safest and most effective pain management possible 1.
From the Research
Methadone Opioid Equivalent with Dilaudid (Hydromorphone)
- The methadone opioid equivalent with Dilaudid (hydromorphone) is not directly stated in the provided studies, but some studies provide dose ratios between methadone and hydromorphone 2.
- A retrospective study found that the hydromorphone/methadone ratio was 1.14:1, which is 5 to 10 times higher than expected 2.
- The dose ratio between hydromorphone and methadone correlated with total opioid dose, with a ratio of 1.6 in patients receiving more than 330 mg of hydromorphone per day prior to the change, versus 0.95 in patients receiving less than or equal to 330 mg of hydromorphone per day 2.
- Another study discussed the concept of opioid equianalgesia and limitations in current dose conversion systems, but did not provide a specific dose ratio between methadone and hydromorphone 3.
- A study on switching from methadone to a different opioid found that the mean dose ratio for oral methadone to oral morphine equivalent daily dose (MEDD) was 1:4.7, but did not provide a direct comparison with hydromorphone 4.