Opioid Morphine Equivalents Including Fentanyl
For converting to transdermal fentanyl, use the following conversions: 60 mg/day oral morphine = 25 mcg/hour fentanyl patch, 120 mg/day oral morphine = 50 mcg/hour patch, 180 mg/day oral morphine = 75 mcg/hour patch, and 240 mg/day oral morphine = 100 mcg/hour patch. 1, 2
Conversion Table: Oral Morphine to Transdermal Fentanyl
The NCCN guidelines provide specific conversion ratios for transdermal fentanyl based on 24-hour oral morphine requirements 1:
- 25 mcg/hour fentanyl patch = 60 mg/day oral morphine 1, 2
- 50 mcg/hour fentanyl patch = 120 mg/day oral morphine 1, 2
- 75 mcg/hour fentanyl patch = 180 mg/day oral morphine 1, 2
- 100 mcg/hour fentanyl patch = 240 mg/day oral morphine 1, 2
For doses requiring >100 mcg/hour, multiple patches should be used 2.
Conversion Table: Oral Hydromorphone to Transdermal Fentanyl
Direct conversions from oral hydromorphone to transdermal fentanyl are provided in NCCN guidelines 1:
- 25 mcg/hour fentanyl patch = 7.5 mg/day oral hydromorphone 1
- 50 mcg/hour fentanyl patch = 15 mg/day oral hydromorphone 1
- 75 mcg/hour fentanyl patch = 22.5 mg/day oral hydromorphone 1
- 100 mcg/hour fentanyl patch = 30 mg/day oral hydromorphone 1
Parenteral Morphine to Transdermal Fentanyl
For IV/subcutaneous morphine conversions 1:
- 25 mcg/hour fentanyl patch = 20 mg/day IV/SubQ morphine 1
- 50 mcg/hour fentanyl patch = 40 mg/day IV/SubQ morphine 1
- 75 mcg/hour fentanyl patch = 60 mg/day IV/SubQ morphine 1
- 100 mcg/hour fentanyl patch = 80 mg/day IV/SubQ morphine 1
Parenteral Hydromorphone to Transdermal Fentanyl
For IV/subcutaneous hydromorphone 1:
- 25 mcg/hour fentanyl patch = 1.5 mg/day IV/SubQ hydromorphone 1
- 50 mcg/hour fentanyl patch = 3.0 mg/day IV/SubQ hydromorphone 1
- 75 mcg/hour fentanyl patch = 4.5 mg/day IV/SubQ hydromorphone 1
- 100 mcg/hour fentanyl patch = 6.0 mg/day IV/SubQ hydromorphone 1
IV Fentanyl to Transdermal Fentanyl
When converting from continuous IV fentanyl infusion to transdermal fentanyl, use a straight 1:1 ratio (e.g., 50 mcg/hour IV fentanyl = 50 mcg/hour transdermal fentanyl patch). 1
Critical Safety Considerations
When converting to transdermal fentanyl, reduce the calculated equianalgesic dose by 25-50% to account for incomplete cross-tolerance between opioids. 1 This dose reduction is essential because the conversion tables are conservative when converting TO fentanyl but would overestimate doses when converting FROM fentanyl to other opioids 2.
Pain must be relatively well-controlled on short-acting opioids before initiating the fentanyl patch. 1 Transdermal fentanyl is not appropriate for unstable pain requiring frequent dose adjustments 1.
Prescribe short-acting opioid rescue medication (typically morphine or equivalent) for breakthrough pain, particularly during the first 8-24 hours after patch application. 1, 3 Continue breakthrough medication even after the patch dose stabilizes 3.
Do not titrate the fentanyl patch dose for at least 3 days after initial application, and wait at least 6 days between subsequent dose adjustments to allow fentanyl levels to reach steady state. 2
After 2-3 days at steady state, increase the patch dosage based on the average daily requirement of rescue opioid medication. 1, 3 The FDA recommends using a ratio of 45 mg/24 hours of oral morphine to justify a 12 mcg/hour increase in fentanyl patch dose 2.
Important Contraindications and Warnings
Use fentanyl patches only in opioid-tolerant patients. 1 The patches are contraindicated in opioid-naïve patients due to risk of fatal respiratory depression 2.
Avoid heat application (fever, heating pads, electric blankets, heat lamps) as this accelerates fentanyl absorption and can cause overdose. 1
The fentanyl patch typically lasts 72 hours, though some patients require replacement every 48 hours. 1