What is the morphine equivalent of a 100 microgram (mcg) fentanyl patch?

From the Guidelines

A 100 microgram per hour fentanyl patch is equivalent to 240 mg of oral morphine per day, based on the conversion factor of 2.4 provided by the CDC clinical practice guideline for prescribing opioids for pain - United States, 2022 1. This means that over a 24-hour period, the fentanyl patch delivers an amount of opioid analgesia similar to what you would get from taking 240 mg of oral morphine spread throughout the day.

Key Considerations

• Fentanyl is significantly more potent than morphine, which is why such a small amount of fentanyl provides pain relief equivalent to a much larger amount of morphine.
• These are approximate equivalences, and individual responses to opioids can vary 1.
• When converting between opioids, healthcare providers typically start with a lower equivalent dose to account for incomplete cross-tolerance and to reduce the risk of overdose.

Clinical Application

• Fentanyl patches are typically changed every 72 hours (3 days) and provide continuous pain relief during that time.
• It's essential to use particular caution with transdermal fentanyl because it is dosed in mcg/hr instead of mg/day, and its absorption is affected by heat and other factors 1.

Important Notes

• Equianalgesic dose conversions are only estimates and cannot account for individual variability in genetics and pharmacokinetics 1.
• The conversion factors should not be applied to dosage decisions related to the management of opioid use disorder 1.

From the FDA Drug Label

TABLE E* RECOMMENDED INITIAL FENTANYL TRANSDERMAL SYSTEM DOSE BASED UPON DAILY ORAL MORPHINE DOSE 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

To determine how much morphine 100 micrograms of fentanyl patch equals, we need to find the corresponding oral morphine dose.

• According to Table E, a fentanyl transdermal system dose of 100 mcg/hr corresponds to a daily oral morphine dose of 315-404 mg. Therefore, 100 micrograms of fentanyl patch equals 315-404 mg of oral morphine per day, or approximately 13.1-16.8 mg of oral morphine per hour, since there are 24 hours in a day. 2

From the Research

Fentanyl and Morphine Comparison

• Fentanyl is a synthetic opioid that is more potent than morphine, but the exact equivalent dose is not directly stated in the provided studies 3, 4, 5, 6, 7.
• However, it is known that fentanyl is approximately 50-100 times more potent than morphine 4.
• To determine the equivalent dose of morphine for a 100 microgram fentanyl patch, we need to consider the potency ratio between the two opioids.
• Assuming a potency ratio of 50-100, a 100 microgram fentanyl patch would be equivalent to 5-10 milligrams of morphine per hour, but this is not explicitly stated in the provided studies.

Pharmacokinetics and Pharmacodynamics

• The pharmacokinetics and pharmacodynamics of fentanyl and morphine are different, which can affect their clinical efficacy and safety profiles 5, 6.
• Fentanyl has a faster onset of action and a shorter duration of action compared to morphine, which can influence its potential for abuse and overdose 4, 6.
• The studies suggest that fentanyl interacts with non-opioid receptors and transporters, which may contribute to its unique clinical effects, including rapid onset muscular rigidity and vocal cord closure 6.

Clinical Implications

• The differences in potency, pharmacokinetics, and pharmacodynamics between fentanyl and morphine have important clinical implications for pain management and overdose risk 3, 4, 5, 6, 7.
• Healthcare providers should be aware of these differences when prescribing opioids and monitor patients closely for signs of overdose or adverse effects.
• Further research is needed to fully understand the clinical effects of fentanyl and morphine and to develop safer and more effective pain management strategies.