Maximum Fentanyl Dosing in 24 Hours
There is no absolute maximum dose of fentanyl in a 24-hour period, as dosing should be titrated based on patient response, opioid tolerance, and pain control requirements, with multiple patches being used for dosage requirements exceeding 100 mcg/h. 1
Transdermal Fentanyl Dosing Guidelines
- Transdermal fentanyl should only be used in patients who are already tolerant to opioid therapy to reduce the risk of respiratory depression 2
- Pain should be relatively well controlled on short-acting opioids before initiating the fentanyl patch, as patches are not recommended for unstable pain requiring frequent dose changes 1, 2
- For fentanyl dosage requirements exceeding 100 mcg/h, multiple patches are used 1
- When converting from continuous parenteral infusion fentanyl to transdermal fentanyl, straight 1:1 ratios are appropriate (e.g., the mcg of parenteral fentanyl should be approximately equal to the mcg/h of transdermal fentanyl) 1
Conversion from Other Opioids to Transdermal Fentanyl
The following conversion table can be used when switching from other opioids to transdermal fentanyl 1, 2:
| Transdermal Fentanyl | Oral Morphine | Oral Oxycodone | Oral Hydromorphone |
|---|---|---|---|
| 25 mcg/h | 60 mg/day | 30 mg/day | 7.5 mg/day |
| 50 mcg/h | 120 mg/day | 60 mg/day | 15.0 mg/day |
| 75 mcg/h | 180 mg/day | 90 mg/day | 22.5 mg/day |
| 100 mcg/h | 240 mg/day | 120 mg/day | 30.0 mg/day |
- When converting to fentanyl from other opioids, an as-needed (PRN) dose of morphine or other short-acting opioid should be prescribed and will be needed particularly during the first 8 to 24 hours 1
- Once levels have reached steady state after at least 2-3 days, increase the patch dosage based on the average amount of stable daily PRN opioid required 1
Important Considerations for Fentanyl Administration
- The fentanyl patch analgesic duration is usually 72 hours, but some patients require fentanyl patch replacement every 48 hours 1, 2
- Application of heat (e.g., fever or topical heat from heat lamps, electric blankets) may accelerate transdermal fentanyl absorption and is contraindicated with transdermal fentanyl 1, 2
- Fentanyl levels continue to rise for 12-24 hours after initial application, which is an important consideration when initiating therapy 2, 3
- When converting from continuous parenteral infusion fentanyl of longer duration (>7-14 days), dose adjustments may be needed due to accumulated tolerance 1
Safety Considerations
- A significant number of new fentanyl transdermal system users may not have evidence of prior opioid tolerance, especially at higher strengths, increasing the risk of respiratory depression 4
- Depot accumulation of fentanyl within skin tissue results in a significant delay (17 to 48 hours) before maximum plasma concentration is achieved 5
- The most serious adverse event associated with fentanyl is hypoventilation, which occurred in approximately 2% of cancer patients in clinical studies 5
Rescue Dosing for Breakthrough Pain
- Allow rescue doses of short-acting opioids of 10%-20% of 24-hour oral dose (mg) as needed 1
- For transmucosal fentanyl (for breakthrough pain), initiate with the lowest dose (200-mcg lozenge or 100-mcg buccal tablet or 200-mcg buccal soluble film) and titrate to effect 1
- Ongoing need for repeated rescue doses may indicate the need to increase the baseline fentanyl dose 1