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Oxymorphone extended release does not affect CYP2C9 or CYP3A4 metabolic pathways
Michael Adams1, Henry J Pieniaszek, Arnold R Gammaitoni
1SFBC-New Drug Services Inc, Kennett Square, Pennsylvania, USA.
Journal of Clinical Pharmacology
|February 11, 2005
Summary
Extended-release oxymorphone showed minimal impact on CYP2C9 and CYP3A4 metabolic activities in healthy individuals. This suggests a low potential for drug-drug interactions when using oxymorphone ER.
Area of Science:
- Pharmacology
- Drug Metabolism
- Clinical Pharmacology
Background:
- Cytochrome P450 enzymes, specifically CYP2C9 and CYP3A4, are crucial for drug metabolism.
- Understanding drug-drug interactions (DDIs) is essential for safe and effective pharmacotherapy.
- Oxymorphone is an opioid analgesic, and its metabolic profile requires investigation for potential DDIs.
Purpose of the Study:
- To evaluate the effects of extended-release (ER) oxymorphone on the metabolic activities of CYP2C9 and CYP3A4 in healthy subjects.
- To assess the potential for metabolic drug-drug interactions involving ER oxymorphone.
Main Methods:
- Two 14-day, randomized, open-label, parallel-group studies were conducted.
- Subjects received CYP2C9 (tolbutamide) or CYP3A4 (midazolam, erythromycin breath test) probes.
- Participants were randomized into five groups: high-dose oxymorphone ER + naltrexone, low-dose oxymorphone ER, rifampin (CYP inducer), naltrexone, or controls.
Main Results:
- Rifampin significantly altered probe metabolism on days 7 and 14 (P < .05).
- Low-dose oxymorphone ER did not significantly affect probe metabolism.
- High-dose oxymorphone ER combined with naltrexone also did not significantly impact probe metabolism.
Conclusions:
- Extended-release oxymorphone demonstrates a minimal potential for causing metabolic drug-drug interactions mediated by CYP2C9 or CYP3A4.
- These findings suggest that ER oxymorphone can be safely co-administered with drugs metabolized by these key enzymes with a low risk of significant interactions.