Duration of Action for Oxycodone Immediate Release (Oxy IR)
Immediate release oxycodone (Oxy IR) has a duration of action of 3-6 hours, with an apparent elimination half-life of 3.5 to 4 hours following oral administration. 1, 2
Pharmacokinetic Profile of Oxycodone IR
- Oxycodone IR has an onset of action within 10-30 minutes after oral administration 1
- Peak effects typically occur within 1-2 hours after administration 2
- The duration of analgesic effect lasts 3-6 hours for immediate release formulations 1, 3
- The elimination half-life ranges from 3.5 to 4 hours 2
- It takes approximately 18 to 24 hours to reach steady-state plasma concentrations with regular dosing 2
Clinical Implications
- Due to its 3-6 hour duration of action, immediate release oxycodone is typically dosed every 4-6 hours for pain management when needed 1, 3
- For breakthrough pain in patients on controlled-release oxycodone, immediate release formulations provide rescue analgesia within the same timeframe 1
- When converting from immediate release to controlled release formulations, the total daily dose can be divided into two doses given 12 hours apart 4, 5
Pharmacological Considerations
- Oxycodone has high oral bioavailability (60-87%) compared to other oral opioids due to lower first-pass metabolism 2, 3
- The drug is primarily metabolized in the liver via CYP3A4 and CYP2D6 pathways 2
- Food intake can enhance the extent of absorption (27% increase in AUC) but not the rate, and may delay the time to maximum concentration 2
Special Population Considerations
- In patients with hepatic impairment, clearance may decrease, potentially extending the duration of action 2
- Patients with renal impairment may experience increased adverse effects as the drug and its metabolites are primarily excreted via the kidney 2
- In patients with end-stage liver disease, oxycodone should be avoided according to European Association for the Study of the Liver (EASL) recommendations 1
Comparison with Extended-Release Formulations
- While immediate release oxycodone lasts 3-6 hours, controlled-release formulations provide 10-12 hours of analgesia 1
- Extended-release formulations should not be used for as-needed pain relief or for acute pain management 1
- Immediate release formulations are preferred for dose titration and management of breakthrough pain 1, 6
Common Pitfalls to Avoid
- Administering immediate release oxycodone more frequently than every 4 hours can lead to accumulation and increased risk of adverse effects 1
- Crushing or breaking controlled-release formulations can destroy their extended-release properties and lead to rapid absorption, potentially causing overdose 1
- Immediate release oxycodone should not be used with other CNS depressants without appropriate dose adjustments due to increased risk of respiratory depression 1