Oxymorphone conversion and pharmacology
Potent semi-synthetic opioid analgesic.
Equianalgesic estimate
1mg Parenteral ≈ 10mg Oral ≈ 10mg Parenteral Morphine
Published equianalgesic ratios vary between references and with clinical context. Read how to interpret conversion results before applying an estimate.
Mechanism of action
Potent agonist, primarily acting on mu-opioid receptors.
Brand names: Opana, Opana ER
Pharmacokinetics
- Protein binding
- 10-12%
- Volume of distribution
- ~4 L/kg
- Half-life
- 7-9 hours (IR), 9-11 hours (ER)
| Route | Form | Bioavailability | Onset | Peak | Duration |
|---|---|---|---|---|---|
| Oral | IR | ~10% | 30 min | 0.5-1 hour | 4-6 hours |
| Parenteral | IV | — | 5-10 min | — | 3-6 hours |
Metabolism
- Glucuronidation (Phase II)
Metabolites
- 6-hydroxyoxymorphone Active, but present in low concentrations and unlikely to contribute significantly.
Extensive first-pass metabolism results in very low oral bioavailability. Not significantly metabolized by CYP enzymes.
Renal and hepatic impairment
Renal
Use with caution; metabolites accumulate. CrCl <50: initiate at lowest dose and titrate slowly.
Hepatic
Bioavailability increases significantly. Moderate/Severe impairment: Contraindicated or requires significant dose reduction.
Clinical cautions
- Must be taken on an empty stomach (food, especially high-fat meals, increases absorption significantly).
- Alcohol significantly increases plasma levels (especially with ER formulation), risking fatal overdose.
For qualified healthcare professionals. This page is an educational reference, not prescribing advice. Check medicine information and conversion factors against a current clinical source and local guidance.
Other opioids in this reference
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Last updated 30 August 2026. Read how to interpret conversion results and the Terms of Service.