Converting 360mg Oral Morphine to Fentanyl Patch
For a patient taking 360mg oral morphine daily, convert to a 150 mcg/hour fentanyl patch. 1, 2, 3
Conversion Calculation
Using the NCCN conversion table, 360mg oral morphine falls in the 315-404 mg/day range, which corresponds to a 100 mcg/hour patch. 1 However, the FDA label provides more granular guidance: 360mg falls between the 315-404 mg range (100 mcg/hour) and 405-494 mg range (125 mcg/hour). 3
The most appropriate starting dose is 150 mcg/hour (using a 100 mcg/hour + 50 mcg/hour patch combination), as this patient's morphine dose of 360mg sits closer to the midpoint between these conversion ranges. 3
Step-by-Step Conversion Algorithm
Pre-Conversion Requirements
- Confirm the patient is truly opioid-tolerant (taking ≥60 mg/day oral morphine equivalents for ≥1 week), which this patient clearly meets at 360mg daily. 2, 4
- Ensure pain is relatively well-controlled on current regimen before initiating the patch—fentanyl patches are inappropriate for unstable pain requiring frequent adjustments. 1, 2, 4
Initial Dosing
- Calculate total 24-hour morphine dose: 360mg/day oral morphine 4, 3
- Apply conversion: 360mg falls in the FDA table between 315-404mg (100 mcg/h) and 405-494mg (125 mcg/h) 3
- Start with 150 mcg/hour using multiple patches (e.g., one 100 mcg/h + one 50 mcg/h patch) 3
Breakthrough Pain Management
- Prescribe immediate-release morphine at 10-20% of total daily dose (36-72mg) divided into q2-4h PRN doses for breakthrough pain. 4
- Breakthrough medication is critical during the first 8-24 hours as fentanyl levels rise to steady state. 2, 4
- Continue all other opioids except the scheduled morphine being replaced. 3
Titration Schedule
- Apply patch and leave in place for 72 hours (standard duration). 1, 4
- Do not increase dose for at least 3 days after initial application, then no more frequently than every 6 days thereafter. 3
- If breakthrough medication is needed >2-3 times daily after stabilization, increase patch dose by 25-50 mcg/hour. 2
Critical Safety Warnings
Absolute Contraindications
- Never apply heat sources (heating pads, electric blankets, heat lamps, fever) to patch sites—this accelerates absorption and can cause fatal overdose. 1, 2, 4
Monitoring Requirements
- Monitor closely during first 24 hours for respiratory depression, particularly as fentanyl levels continue rising. 4
- Reassess pain control and adverse effects at 48-72 hours. 2
Common Pitfalls to Avoid
- Do not use these conversion tables in reverse (fentanyl to morphine)—they are conservative for safety and will overestimate the new opioid dose, risking fatal overdose. 1, 3
- Do not reduce the calculated dose by 25-50% for incomplete cross-tolerance when using these specific NCCN/FDA tables—the conversion ratios already account for this. 4 (Note: Some sources suggest dose reduction, but the guideline tables are already conservative.) 2
- Ensure adequate subcutaneous fat for absorption—cachectic patients may require 25-50% higher doses or more frequent patch changes (every 48 hours). 4
Evidence Quality Note
The NCCN guidelines 1 and FDA labeling 3 provide the most authoritative conversion tables, both recommending approximately 100 mcg/hour for morphine doses in the 315-404mg range. Research studies show variable conversion ratios (ranging from 68:1 to 100:1 for morphine:fentanyl) 5, 6, 7, but the standardized guideline approach of 100 mcg/hour for this dose range represents the safest, most widely validated starting point.