Oxycodone to Morphine Conversion
Roxicodone (oxycodone) 10 mg every 6 hours (40 mg/day total) is equivalent to 60 mg/day of oral morphine, calculated using the CDC's conversion factor of 1.5 for oxycodone. 1
Calculation Method
- Total daily oxycodone dose: 10 mg × 4 doses = 40 mg/day 1
- Apply CDC conversion factor: 40 mg × 1.5 = 60 MME (morphine milligram equivalents) per day 1
- This equals: Morphine 15 mg every 6 hours, or 20 mg every 8 hours 1
The 2022 CDC Clinical Practice Guideline provides the standardized conversion factor of 1.5 for oxycodone, meaning oxycodone is approximately 1.5 times more potent than morphine. 1 This conversion factor is consistent with clinical research showing an oxycodone-to-morphine ratio of 1:1.5-2. 2
Critical Clinical Caveats
Important: These conversion factors should NOT be used directly when switching a patient from oxycodone to morphine. 1 The CDC explicitly warns that when converting between opioids, the new opioid should be dosed at a substantially lower dose (typically 25-50% reduction) than the calculated MME to avoid overdose due to incomplete cross-tolerance and individual pharmacokinetic variability. 1
If Actually Converting This Patient to Morphine:
- Calculated equivalent: 60 mg/day morphine 1
- Reduce by 25-50%: Start at 30-45 mg/day morphine 1
- Practical dosing: Begin with morphine 10 mg every 6-8 hours (30-40 mg/day) 1
- Provide breakthrough medication: Short-acting morphine 5-10 mg every 2 hours as needed 1
Context for This Dose
This patient's current regimen of 40 mg/day oxycodone (60 MME/day) exceeds the CDC's recommended threshold of 50 MME/day, which triggers the need for careful reassessment of benefits versus risks. 1 The CDC notes that many patients do not experience additional benefit in pain or function from doses ≥50 MME/day but are exposed to progressively increasing risks. 1
Additional Considerations
Equianalgesic conversions are estimates only and cannot account for individual variability in genetics and pharmacokinetics. 1 Research demonstrates significant variability in how clinicians perform opioid conversions, with standard deviations often exceeding 30% of mean values. 3 Oxycodone has more predictable metabolism than morphine, making titration easier, and may be associated with less toxicity including less nausea, hallucinations, and pruritus. 2