Long-Acting Morphine Equivalent for Oxycodone 60 mg Q8 Hours
For a patient taking oxycodone extended-release 60 mg every 8 hours (180 mg/day total), the long-acting morphine equivalent is 270 mg/day oral morphine, typically administered as 135 mg every 12 hours of extended-release morphine. 1
Calculation Steps
Step 1: Calculate Total Daily Oxycodone Dose
- Oxycodone 60 mg × 3 doses per day (Q8 hours) = 180 mg/day total oxycodone 1
Step 2: Apply Conversion Ratio
- The standard conversion factor from oral oxycodone to oral morphine is 1.5:1 1
- 180 mg oxycodone × 1.5 = 270 mg oral morphine per day 1
Step 3: Divide into Extended-Release Dosing
- For extended-release morphine given every 12 hours: 270 mg ÷ 2 = 135 mg every 12 hours 2
- Alternatively, if using every 8-hour dosing: 270 mg ÷ 3 = 90 mg every 8 hours 2
Critical Safety Adjustment
If you are rotating between opioids (not just converting for reference), you must reduce the calculated equianalgesic dose by 25-50% to account for incomplete cross-tolerance. 2, 3
- If pain was well-controlled on oxycodone: reduce morphine dose to 135-202.5 mg/day (50-75% of calculated dose) 2
- If pain was poorly controlled: may use 100% of calculated dose (270 mg/day) or even increase by 25% 2
Breakthrough Pain Coverage
Prescribe immediate-release morphine at 10-20% of the 24-hour dose for breakthrough pain:
- 10-20% of 270 mg = 27-54 mg per day available for rescue dosing 2
- Divide into individual rescue doses: approximately 5-10 mg immediate-release morphine every 2-4 hours as needed 2
Important Clinical Caveats
Avoid morphine in patients with renal failure due to accumulation of renally cleared toxic metabolites 2
Monitor closely during the first 24-48 hours after conversion, with more frequent assessment if the patient has unstable pain or is actively dying 1, 3
Be prepared to titrate upward by 25-50% if pain control is inadequate after the initial conversion 2, 1