Tramadol conversion and pharmacology
A synthetic (codeine analog) analgesic with a dual mechanism of action.
Equianalgesic estimate
120mg Oral ≈ 30mg Oral Morphine (Variable)
Published equianalgesic ratios vary between references and with clinical context. Read how to interpret conversion results before applying an estimate.
Mechanism of action
Weak mu-opioid receptor agonist (parent drug and M1 metabolite). Inhibitor of serotonin and norepinephrine reuptake (SNRI).
Brand names: Ultram, ConZip
Pharmacokinetics
- Protein binding
- ~20%
- Volume of distribution
- 2.6-2.9 L/kg
- Half-life
- ~6.3 hours (parent), ~7.4 hours (M1)
| Route | Form | Bioavailability | Onset | Peak | Duration |
|---|---|---|---|---|---|
| Oral | IR | ~75% | ~1 hour | 2-3 hours | 4-6 hours |
Metabolism
- CYP2D6 (O-demethylation)
- CYP3A4/CYP2B6 (N-demethylation)
Metabolites
- O-desmethyltramadol (M1) Significantly higher affinity for mu-receptor (6x more potent) than parent drug; primary driver of opioid effect.
Acts as a prodrug for opioid activity. Metabolism highly dependent on CYP2D6 genotype. CYP2D6 inhibitors reduce analgesic efficacy.
Renal and hepatic impairment
Renal
CrCl <30 mL/min: Increase dosing interval to q12h (IR), max 200mg/day. ER not recommended.
Hepatic
Metabolism reduced. In severe cirrhosis, reduce dose (e.g., 50mg q12h for IR).
Clinical cautions
- Lowers seizure threshold, even at recommended doses.
- Significant risk of Serotonin Syndrome, especially with other serotonergic drugs (SSRIs, SNRIs, MAOIs, triptans).
- Risk of hypoglycemia.
- Withdrawal can include both opioid and SNRI symptoms.
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.