Nalbuphine
Nubain
Mixed opioid — κ-agonist / μ-antagonist
κ-receptor agonist + μ-receptor antagonist. Ceiling on respiratory depression. Reverses μ-mediated pruritus/respiratory depression while preserving some analgesia.
Indications
- •Opioid-induced pruritus (esp. neuraxial morphine)
- •Moderate analgesia
- •Partial reversal of respiratory depression keeping analgesia
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| Pruritus | 2.5–5 mg IV | — |
| Analgesia | 0.1 mg/kg IV (max ~10 mg) | — |
Pharmacokinetics
Onset 2–3 min IV, duration 3–6 h.
Hemodynamic effects
Minimal.
Respiratory effects
Ceiling effect — less risk of profound depression than pure agonists.
Side effects
- !Sedation
- !Dysphoria (κ effect)
- !Can precipitate withdrawal in opioid-dependent patients
Contraindications
- ×Opioid dependence (precipitates withdrawal)
Reversal / antidote
Naloxone
Clinical pearls
- ★Treats neuraxial-morphine pruritus without fully reversing analgesia.
- ★Ceiling on respiratory depression — but avoid in chronic opioid users (withdrawal).
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.
Suggested reading
- •Stoelting & Hines, Pharmacology & Physiology in Anesthetic Practice, 6e
- •Miller's Anesthesia, 9e
- •FDA package insert
