Tapentadol conversion and pharmacology
A centrally acting analgesic with a dual mode of action, pharmacologically distinct from tramadol.
Equianalgesic estimate
100mg Oral ≈ 20mg Oral Morphine (approx)
Published equianalgesic ratios vary between references and with clinical context. Read how to interpret conversion results before applying an estimate.
Mechanism of action
Mu-opioid receptor agonist and Norepinephrine Reuptake Inhibitor (NRI). Minimal serotonin reuptake inhibition.
Brand names: Nucynta, Nucynta ER
Pharmacokinetics
- Protein binding
- ~20%
- Volume of distribution
- ~540 L
- Half-life
- ~4 hours (IR), 5-6 hours (ER)
| Route | Form | Bioavailability | Onset | Peak | Duration |
|---|---|---|---|---|---|
| Oral | IR | 32% | 30-45 min | 1.25 hours | 4-6 hours |
| Oral | ER | — | — | 3-6 hours | 12 hours |
Metabolism
- Glucuronidation (UGT1A9, UGT2B7) (major, ~70%)
- CYP2C19/CYP2C9/CYP2D6 (minor)
Not a prodrug; analgesic activity resides in the parent compound. Primarily Phase II metabolism. Low risk of CYP-related drug interactions.
Renal and hepatic impairment
Renal
Mild/Moderate: No adjustment needed. Severe (CrCl <30): Not recommended.
Hepatic
Mild: No adjustment. Moderate: Reduce dose and frequency. Severe: Not recommended.
Clinical cautions
- Dual mechanism may provide better efficacy in neuropathic pain.
- Lower incidence of GI side effects compared to pure mu-agonists like oxycodone.
- Lower risk of serotonin syndrome compared to tramadol, but contraindicated with MAOIs (within 14 days).
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.
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Last updated 30 August 2026. Read how to interpret conversion results and the Terms of Service.