What is the equivalent dose of OxyContin (oxycodone) for a patient taking 5 mg of morphine every 8 hours?

OxyContin Equivalent Dose for 5 mg Morphine Every 8 Hours

The equivalent OxyContin dose is 10 mg every 12 hours (total daily dose of 20 mg).

Conversion Calculation

• The patient is currently taking 5 mg morphine every 8 hours, which equals 15 mg total daily morphine dose 1
• Oxycodone has an oral potency ratio of approximately 1.5-2:1 compared to morphine, meaning oxycodone is roughly twice as potent as morphine 2
• Using the conservative 2:1 conversion ratio: 15 mg morphine ÷ 2 = 7.5 mg oxycodone daily 2
• Round up to 10 mg OxyContin every 12 hours (20 mg total daily) to ensure adequate analgesia, as this represents the lowest available controlled-release formulation 2

Dosing Schedule Considerations

• OxyContin (controlled-release oxycodone) is designed for 12-hourly administration and maintains stable plasma levels within 24 hours, which is faster than morphine's 2-7 days 2
• The 12-hour formulation provides consistent analgesia throughout the dosing interval when properly titrated 3, 4
• Approximately 93% of patients achieve satisfactory analgesia on a 12-hour regimen with appropriate dose titration 5

Breakthrough Pain Management

• Provide immediate-release oxycodone for breakthrough pain at a dose of 10-20% of the total 24-hour dose, which would be 2-4 mg as needed 6
• If the patient requires more than 3-4 breakthrough doses daily, increase the scheduled OxyContin dose by 25-50% rather than shortening the dosing interval 6

Critical Safety Points

• Do not break, chew, or crush OxyContin tablets, as this destroys the controlled-release mechanism and can lead to rapid drug release and potential overdose 2
• Institute prophylactic bowel regimen with stimulant laxatives, as constipation is universal with opioid therapy 6
• Monitor for common side effects including nausea, constipation, and drowsiness, though oxycodone causes somewhat less nausea and pruritus than morphine 2

Dose Titration Strategy

• If pain returns consistently before the next 12-hour dose, increase the regular OxyContin dose rather than shortening the dosing interval 1
• There is no advantage to increasing dosing frequency and considerable disadvantage in terms of convenience and compliance 1
• Re-evaluate within 24 hours after any dose adjustment, as steady state is reached within this timeframe 6