Nalbuphine (Nubain)

Pruritus Treatment - Best known perioperative use is treating neuraxial opioid-induced pruritus (OIP) — particularly after intrathecal or epidural morphine. Low-dose nalbuphine (2.5-5 mg IV) relieves the itch without fully reversing analgesia. Often more effective than diphenhydramine for this indication.

Ceiling Effect on Respiratory Depression - Unlike pure mu agonists, nalbuphine has a ceiling on respiratory depression, which makes it somewhat safer in monitored settings. That said, it still causes significant sedation and respiratory depression at clinical doses — don't get complacent.

Opioid Reversal Risk - If your patient is on chronic opioids or received large intraoperative doses of a full mu agonist, nalbuphine can precipitate acute withdrawal — agitation, tachycardia, hypertension, and pain. Use with caution or avoid in opioid-tolerant patients.

Analgesia Ceiling - Has a ceiling analgesic effect as well. Don't expect it to manage severe pain the way morphine or hydromorphone would — it's better suited as an adjunct or for mild-moderate pain.

Dysphoria - Kappa agonism can cause unpleasant psychotomimetic effects — dysphoria, anxiety, strange sensations. More likely at higher doses.

Excessive Effect - Sedation and respiratory depression: supportive care, airway management. Naloxone will reverse effects, but titrate carefully to avoid precipitating pain or full withdrawal.

Drug Interactions - Additive CNS and respiratory depression with other opioids, benzos, and sedatives. Antagonizes effects of pure mu agonists — don't give after full agonist opioids expecting additive analgesia; you may reduce it.

Pediatric Implications - Used for OIP in pediatric patients. Weight-based dosing (0.05-0.1 mg/kg IV). Generally well tolerated. Same ceiling effect and withdrawal precautions apply.

Obstetric Implications - Crosses the placenta. Has been used for labor analgesia, but neonatal respiratory depression and withdrawal are risks. Not commonly used in modern obstetric anesthesia. Caution if given near delivery.

Relative:

Opioid-dependent patients (risk of precipitating withdrawal)

Patients requiring full mu agonist analgesia

Caution:

Head injury or elevated ICP (sedation complicates neurological assessment)

Hepatic impairment

Emotional instability or history of substance use disorder (dysphoria risk)

Analgesia: 5-20 mg IV q3-6h PRN

Opioid-induced pruritus: 2.5-5 mg IV

5-20 mg IM q3-6h PRN

Kappa opioid receptor agonist and mu opioid receptor partial antagonist. Kappa agonism provides analgesia and sedation; mu antagonism partially reverses mu-mediated effects (pruritus, respiratory depression) while competing with full agonists at the receptor.

Hepatic

Renal and biliary

DEA Schedule: not scheduled (no federal abuse potential classification — one of its practical advantages)

Ceiling dose for respiratory depression approximately 30 mg; analgesic ceiling similar

Available as 10 mg/mL and 20 mg/mL concentrations — confirm before drawing up