Tramadol
Ultram
Weak μ-opioid agonist + serotonin/norepinephrine reuptake inhibitor
Weak μ-agonist plus SNRI. Active metabolite (M1, O-desmethyltramadol) via CYP2D6 is the stronger μ-agonist.
Indications
- •Mild–moderate pain
- •Opioid-sparing multimodal analgesia
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| Oral/IV | 50–100 mg q6h (max 400 mg/day) | — |
Pharmacokinetics
Onset ~1 h PO, duration 4–6 h. Hepatic CYP2D6/CYP3A4.
Respiratory effects
Less respiratory depression than equianalgesic pure opioids.
Side effects
- !Lowers seizure threshold
- !Serotonin syndrome (with SSRIs/SNRIs/MAOIs)
- !N/V, dizziness
Contraindications
- ×Seizure disorder
- ×MAOI within 14 days
- ×Concurrent serotonergic drugs (relative)
Reversal / antidote
Naloxone (partial — and may unmask seizures)
Clinical pearls
- ★Dual seizure + serotonin-syndrome risk — screen concurrent serotonergic drugs.
- ★Efficacy is CYP2D6-dependent; a weak choice for severe acute pain.
Other drugs in Narcotics & Analgesics
- Fentanyl
μ-opioid receptor agonist. ~100× potency of morphine.
- Remifentanil
μ-opioid agonist. Ester linkage hydrolyzed by nonspecific tissue + plasma esterases — no organ-dependent clearance.
- Morphine
μ-opioid receptor agonist. Active metabolite morphine-6-glucuronide (M6G) is analgesic and renally cleared — accumulates in renal failure → prolonged sedation/respiratory depression. Causes histamine release.
- Hydromorphone
μ-opioid agonist ~5–7× more potent than morphine. No clinically significant active metabolites → safer than morphine in renal failure. Less histamine release.
- Sufentanil
Most potent opioid in common clinical use — ~1000× morphine, ~10× fentanyl. High lipid solubility.
- Alfentanil
μ-opioid agonist ~1/5–1/10 the potency of fentanyl but FASTEST onset of the family — low pKa means a high non-ionized fraction at physiologic pH.
- Meperidine
μ-opioid agonist ~1/10 morphine, plus κ-agonism (anti-shivering). Active metabolite normeperidine is renally cleared, proconvulsant, and neurotoxic.
- Methadone
μ-opioid agonist with NMDA-receptor antagonism (blunts tolerance + opioid-induced hyperalgesia) and monoamine reuptake inhibition. Very long, variable half-life.
Browse all classes: /reference/drugs
Suggested reading
- •Stoelting & Hines, Pharmacology & Physiology in Anesthetic Practice, 6e
- •Miller's Anesthesia, 9e
- •FDA package insert
