Equivalence of 5 mg IV Oxycodone to IV Morphine
A 5 mg intravenous dose of oxycodone is equivalent to 7.5 mg of intravenous morphine.
Conversion Factors and Ratios
- The CDC establishes a conversion factor of 1.5 for oxycodone to morphine, meaning oxycodone is 1.5 times more potent than morphine 1
- To convert from oxycodone to morphine, multiply the oxycodone dose by 1.5 (5 mg × 1.5 = 7.5 mg) 2
- For intravenous administration, this same conversion factor applies, with 5 mg IV oxycodone being equivalent to 7.5 mg IV morphine 3
- The potency ratio between oxycodone and morphine is consistently reported as 1:1.5-2 across multiple guidelines 3, 2
Clinical Considerations
- Both morphine and oxycodone are full μ-opioid receptor agonists with similar clinical efficacy profiles 4
- When converting between opioids, caution is advised as equianalgesic dose conversions are only estimates and cannot account for individual variability in genetics and pharmacokinetics 1
- The American Thoracic Society clinical policy statement includes oxycodone and morphine in their recommended starting dosages for opioid-naïve patients with moderate to severe pain 1
- For intravenous administration in opioid-naïve patients, morphine is typically started at 2-10 mg IV, which aligns with the calculated equivalent dose of oxycodone 1
Special Considerations and Precautions
- When converting between different opioids, the new opioid is typically dosed at a lower dose than the calculated equivalent to avoid overdose due to incomplete cross-tolerance 1
- Patients with renal impairment may require dose adjustments, with particular caution needed with morphine due to the accumulation of active metabolites 3
- Oxycodone metabolism is reported to be more predictable than morphine, which may make titration easier in some patients 4
- For patients with intolerances to opioids, starting with lower doses (1-2 mg of IV oxycodone) is recommended 5
Monitoring Recommendations
- After administration of either IV oxycodone or morphine, patients should be monitored for efficacy and adverse effects 5
- Common side effects include nausea, constipation, drowsiness, with oxycodone potentially causing somewhat less nausea, hallucinations, and pruritus than morphine 4
- The peak respiratory depressant effect may vary between opioids, necessitating careful monitoring during administration 3
Remember that while these conversion factors provide a useful guideline, clinical judgment and individual patient response should guide dosing decisions in practice.