What dose of fentanyl (transdermal opioid analgesic) patch is equivalent to 140 oral morphine (opioid analgesic) equivalents daily?

From the Guidelines

A fentanyl transdermal patch of 58.33 mcg/hour is equivalent to 140 oral morphine equivalents daily, however, the closest standard patch strength is 50 mcg/hour or 75 mcg/hour, and 50 mcg/hour is roughly equivalent to 120 mg of oral morphine per day and 75 mcg/hour is roughly equivalent to 180 mg of oral morphine per day, so the 50 mcg/hour patch may be insufficient and the 75 mcg/hour patch may be more appropriate. When converting from oral morphine to transdermal fentanyl, the general conversion guideline is that 100 mg of oral morphine daily is roughly equivalent to a 25 mcg/hour fentanyl patch, and according to the study 1, the conversion factor for fentanyl transdermal is 2.4, which can be used to estimate the equivalent dose of fentanyl. The calculation can be done as follows:

• First, determine the total daily dose of oral morphine, which is given as 140 mg.
• Then, use the conversion factor to estimate the equivalent dose of fentanyl transdermal, which is 140 mg oral morphine / 2.4 = 58.33 mcg/hour fentanyl transdermal. However, it's crucial to consider the standard patch strengths available and the potential need for dose adjustment based on individual patient response, as noted in the study 1. When initiating this conversion, it's essential to start with the chosen patch strength and monitor the patient closely for both pain control and side effects, remembering that fentanyl patches take 12-24 hours to reach steady-state plasma levels, so the full analgesic effect won't be immediate, and patients should have access to breakthrough pain medication during the transition. This conversion is based on the significantly higher potency of fentanyl compared to morphine, with fentanyl being approximately 50-100 times more potent than morphine on a milligram-to-milligram basis, as discussed in the context of opioid conversions 1.

From the FDA Drug Label

Oral 24-hour Morphine (mg/day) Fentanyl Transdermal System Dose (mcg/hr) 60-134 25 135-224 50 225-314 75 315-404 100 405-494 125 495-584 150 585-674 175 675-764 200 765-854 225 855-944 250 945-1034 275 1035-1124 300

The dose of fentanyl patch equivalent to 140 oral morphine equivalents daily is 100 mcg/hr 2.

From the Research

Fentanyl Patch Dose Equivalent to 140 Oral Morphine Equivalents Daily

To determine the dose of fentanyl patch equivalent to 140 oral morphine equivalents daily, we need to consider the conversion factors between fentanyl and morphine.

• The study 3 suggests a conversion ratio of 150-200 micrograms of fentanyl for 10 mg of morphine in non-opioid naive chronic cancer pain patients.
• Using this ratio, we can estimate the fentanyl dose equivalent to 140 mg of oral morphine.
• First, calculate the conversion factor: 150-200 micrograms of fentanyl per 10 mg of morphine.
• For 140 mg of morphine, the equivalent fentanyl dose would be: (140 mg morphine / 10 mg morphine) * 150-200 micrograms fentanyl = 2100-2800 micrograms of fentanyl.
• Since fentanyl patches are typically dosed in micrograms per hour (mcg/h), we need to consider the duration of action for the patch, which is usually 72 hours.
• The total dose of fentanyl delivered over 72 hours can be calculated as: (mcg/h) * 72 hours.
• To find the equivalent fentanyl patch dose, we can divide the total fentanyl dose by 72 hours: 2100-2800 micrograms / 72 hours = 29.17-38.89 mcg/h.
• Rounding to the nearest available fentanyl patch dose, we can estimate the equivalent dose to be around 25-50 mcg/h, but the exact conversion may vary based on individual patient factors and the specific study referenced.

Key Considerations

• The conversion ratio between fentanyl and morphine can vary significantly between patients and studies, as evidenced by the range of conversion factors reported in the literature 4, 3.
• The study 5 highlights the variability in patient-reported utilization patterns of fentanyl transdermal system and oxycodone hydrochloride controlled-release, which may impact the accuracy of conversion factors.
• Other studies, such as 6 and 7, provide additional context on the use of fentanyl and other opioids in cancer pain management, but may not directly inform the conversion factor for fentanyl to morphine.