Oxycodone to Morphine ER Conversion
The equivalent dose of morphine extended release (ER) for a patient taking 60mg/day of oxycodone is 90mg/day of morphine ER, based on the CDC's conversion factor of 1.5 for oxycodone to morphine equivalents. 1
Calculation Process
- Determine total daily oxycodone dose: 60mg/day
- Apply conversion factor:
- According to the 2022 CDC Clinical Practice Guideline, oxycodone has a conversion factor of 1.5 1
- 60mg oxycodone × 1.5 = 90mg morphine equivalent
Important Considerations for Conversion
Dosing Caution
- When converting between opioids, start with a lower dose than the calculated morphine equivalent dose (typically 25-50% lower) to account for incomplete cross-tolerance 1
- Initial morphine ER dose might be 60-70mg/day rather than the full 90mg to reduce risk of overdose
Monitoring Requirements
- Monitor the patient closely for:
- Respiratory depression, especially in the first 24-48 hours after conversion
- Pain control adequacy
- Side effects (constipation, nausea, sedation)
Risk Assessment
- The calculated dose of 90mg/day morphine ER exceeds the CDC's 50 MME/day threshold, which warrants careful risk assessment 1
- Before prescribing this dose, clinicians should:
- Evaluate benefits versus risks
- Consider naloxone prescription
- Increase monitoring frequency
Dosing Schedule
- Morphine ER is typically administered every 12 hours
- A 90mg daily dose would typically be divided as 45mg twice daily
- Provide breakthrough pain medication as needed (typically 10-15% of total daily dose)
Common Pitfalls to Avoid
- Calculation errors: Double-check all conversion calculations
- Failure to account for incomplete cross-tolerance: Always reduce the calculated dose when switching between opioids
- Not providing breakthrough medication: Ensure appropriate rescue medication during transition
- Rapid titration: Allow adequate time (3-7 days) to assess response before further dose adjustments
Remember that equianalgesic dose conversions are estimates and cannot account for individual variability in genetics and pharmacokinetics 1. Close monitoring and dose adjustment based on clinical response are essential for safe and effective pain management.