A patient on long-term oral morphine for chronic cancer pain requires opioid rotation to transdermal fentanyl due to intolerable side effects. The oral morphine dose equivalent of transdermal fentanyl 25 mcg/h is approximately:

• A 60 mg/day oral morphine ✓
• B 30 mg/day oral morphine
• C 90 mg/day oral morphine
• D 120 mg/day oral morphine

Explanation

The established equianalgesic conversion for transdermal fentanyl is: fentanyl patch 25 mcg/h ≈ 60–90 mg oral morphine/day (most guidelines use 60 mg/day as the conservative anchor for rotation). Oral to transdermal conversion uses oral morphine equivalents (OME): 100 mg oral morphine ≈ 40 mcg/h fentanyl patch. When rotating opioids, a 25–30% dose reduction is often applied for incomplete cross-tolerance. The patch has an onset of 12–24 hours and reaches steady state in 36–48 hours; overlap with existing opioids for the first 12 hours prevents pain breakthrough during initiation.

Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.