NALBUPHINE
Clinical safety rating: safe
Animal studies have demonstrated safety
Mixed opioid agonist-antagonist; agonist at κ-opioid receptors and antagonist/partial agonist at μ-opioid receptors.
| Metabolism | Hepatic metabolism primarily via glucuronidation and oxidative pathways; minor involvement of CYP450 enzymes. |
| Excretion | Primarily hepatic metabolism; <5% excreted unchanged in urine; about 70% excreted in feces via biliary elimination. |
| Half-life | Terminal elimination half-life is 5 hours; clinically, in hepatic impairment or elderly, half-life may be prolonged up to 8-10 hours. |
| Protein binding | Approximately 50% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | 2.3 L/kg; indicates extensive tissue distribution, consistent with moderate lipophilicity. |
| Bioavailability | Intravenous: 100%; Intramuscular: approximately 80%; Oral: negligible (<20%) due to extensive first-pass metabolism. |
| Onset of Action | Intravenous: 2-3 minutes; Intramuscular: <15 minutes; Subcutaneous: <15 minutes; Oral: not clinically used due to high first-pass metabolism. |
| Duration of Action | Analgesic effect: 3-6 hours; with longer duration for IM/SC vs IV; ceiling effect for respiratory depression limits dose escalation. |
| Molecular Weight | 357.46 |
10-20 mg IV/IM/SC every 3-6 hours as needed for pain; maximum single dose 20 mg, maximum total daily dose 160 mg.
| Dosage form | SOLUTION |
| Renal impairment | CrCl 30-50 mL/min: administer 75% of normal dose every 6 hours; CrCl <30 mL/min: administer 50% of normal dose every 8 hours. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 25%; Child-Pugh C: reduce dose by 50% or use alternative. |
| Pediatric use | 0.1-0.2 mg/kg IV/IM/SC every 3-6 hours as needed; maximum single dose 20 mg. |
| Geriatric use | Initiate at 50% of adult dose (5-10 mg) and titrate cautiously due to increased sensitivity and risk of respiratory depression. |
| 1st trimester | Limited data; avoid unless benefit outweighs risk. Considered relatively safe in short-term use but may be associated with congenital malformations in some studies. |
| 2nd trimester | May cause maternal sedation and respiratory depression; use only if clearly needed. No known teratogenicity. |
| 3rd trimester | Prolonged use may lead to neonatal opioid withdrawal syndrome. Avoid near term due to risk of neonatal respiratory depression. |
Clinical note
CNS depressants may enhance sedative effects Can cause withdrawal in patients dependent on other opioids.
| Placental transfer | Crosses placenta; extent not fully quantified but expected due to low molecular weight and lipid solubility. |
| Breastfeeding | Small amounts excreted in breast milk. Monitor infant for drowsiness, respiratory depression. Generally acceptable for short-term use; avoid chronic use. |
■ FDA Black Box Warning
Risk of respiratory depression, particularly in opioid-naive patients; risk of dependence and abuse; concomitant use with benzodiazepines or CNS depressants may cause profound sedation, respiratory depression, coma, and death.
| Common Effects | Sedation |
| Serious Effects |
Hypersensitivity to nalbuphine or any componentUse of MAO inhibitors within 14 daysAcute or severe bronchial asthma in non-monitored settingGastrointestinal obstructionRespiratory depression in absence of resuscitative equipment
| Precautions | Respiratory depression may occur, especially in elderly, cachectic, or debilitated patients, Avoid use in patients with head injury or increased intracranial pressure, May precipitate withdrawal in opioid-dependent patients, Hypotension, biliary tract spasm, and seizure risk |
| Food/Dietary |
Loading safety data…
| Lactation Rating | L2 (Probably Compatible) |
| Teratogenic Risk | FDA Category C. First trimester: Limited human data, no evidence of major malformations in animal studies at 4-6x MRHD. Second/third trimester: Chronic use may cause neonatal opioid withdrawal syndrome (NOWS) including irritability, hypertonia, tremors, poor feeding. Use only if benefit outweighs risk. |
| Fetal Monitoring | Maternal: Respiratory rate, sedation level, blood pressure, heart rate. Fetal: Continuous fetal heart rate monitoring during labor; assess for bradycardia or non-reassuring patterns. Newborn: Observe for respiratory depression and withdrawal symptoms for at least 48 hours after delivery. |
| Fertility Effects | No known direct effect on fertility in humans. Animal studies show no impairment of fertility at doses up to 4x MRHD. May cause hyperprolactinemia and reversible menstrual irregularities with chronic use. |
| No significant food-drug interactions. Avoid alcohol and grapefruit juice as they may enhance CNS depression. |
| Clinical Pearls | Nalbuphine is a mixed agonist-antagonist opioid with a ceiling effect for respiratory depression, making it safer than pure agonists. It can precipitate withdrawal in opioid-dependent patients. Monitor for sedation and hypotension. Reversal with naloxone may be less effective. Use with caution in hepatic impairment. Not recommended for chronic pain due to psychotomimetic effects. |
| Patient Advice | Take exactly as prescribed; do not increase dose or frequency without consulting your doctor. · Avoid alcohol and other central nervous system depressants (e.g., benzodiazepines, sleep aids) as they can increase dizziness and drowsiness. · Do not drive or operate heavy machinery until you know how nalbuphine affects you. · Report any signs of withdrawal (e.g., restlessness, tearing, runny nose, yawning, sweating) if you have been taking other opioids. · Seek emergency care if you experience trouble breathing, severe dizziness, or hallucinations. · Do not stop abruptly; tapering may be needed to avoid withdrawal symptoms. |