From the Guidelines
To convert from IV fentanyl to IV morphine, multiply the daily fentanyl dose by a factor of 60 to calculate the equipotent dose of morphine, then divide this dose by 4 and administer it in 6 divided doses every 4 hours, titrating as needed for adequate effect. This conversion method is based on the study by 1, which provides a step-by-step approach to converting continuous intravenous fentanyl to intermittent intravenous morphine. The key steps in this process include:
- Calculating the 24-hour fentanyl dose based on the target hourly infusion rate
- Multiplying the daily fentanyl dose by 60 to determine the equipotent dose of morphine, assuming a fentanyl: morphine ratio of 60:1
- Dividing the calculated morphine dose by 4 to account for the longer half-life of morphine
- Administering the resulting dose in 6 divided doses every 4 hours, with titration as needed over 12 to 24 hours to achieve adequate pain control. It's essential to monitor the patient closely after conversion for potential side effects, such as respiratory depression, sedation, and hypotension, and to adjust the morphine dose accordingly.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Conversion from IV Fentanyl to IV Morphine
- The conversion between IV fentanyl and IV morphine is not directly established in the provided studies.
- However, a study 2 mentions the conversion ratios for IV:EP:IT fentanyl and conversion from IT morphine/hydromorphone to IT fentanyl, but it does not provide a direct conversion ratio from IV fentanyl to IV morphine.
- Another study 3 compares the effects of low-dose ketamine, fentanyl, and morphine on hemorrhagic tolerance and analgesia in humans, but it does not provide information on conversion ratios between these opioids.
- A study 4 discusses the amplification of established neuropathic pain in male rats by oxycodone, fentanyl, and morphine, but it does not provide information on conversion ratios between these opioids.
Available Conversion Information
- The study 2 provides information on the conversion of IT opioids from morphine/hydromorphone to fentanyl in patients with IT pumps, but it does not provide a direct conversion ratio from IV fentanyl to IV morphine.
- The mean IT morphine equivalent dose at initial conversion was 15.8 mg/day, and the mean fentanyl IT starting dose was 0.73 mg/day.
- The mean fentanyl dose at the end of titration was 0.94 mg/day, which represented a significant 25.1% mean dose increase.
Limitations
- There are no direct conversion ratios from IV fentanyl to IV morphine available in the provided studies.
- The available information is limited to specific studies and may not be generalizable to all patients or clinical settings.