Nalbuphine hydrochloride is a semi-synthetic opioid agonist-antagonist analgesic of the phenanthrene series. It is a potent analgesic with a potency approximately equal to morphine on a milligram basis. It is used for the relief of moderate to severe pain. In the Indian context, it is a valuable option for post-operative pain, trauma, and cancer pain, offering a ceiling effect on respiratory depression which provides a wider safety margin compared to pure mu-opioid agonists.
Adult: Usual dose: 10 mg (1 ml of 10 mg/ml solution) administered IV, IM, or SC every 3-6 hours as needed for pain. For severe pain, a dose of 20 mg may be required. Single doses should not exceed 20 mg. Total daily dose should not exceed 160 mg.
Note: Can be administered undiluted by slow IV injection over 2-3 minutes. For IM/SC, inject into a large muscle mass or subcutaneous tissue. Rotate injection sites. Do not mix in same syringe with other drugs unless compatibility is known. Aspirate before injection to avoid intravascular administration.
Nalbuphine binds with high affinity to kappa-opioid receptors (agonist) and with lower affinity to mu-opioid receptors (partial antagonist). Its analgesic effect is primarily mediated through agonist activity at kappa receptors in the brain and spinal cord. The antagonistic activity at mu receptors limits its euphoric effects, abuse potential, and provides a ceiling on respiratory depression.
Pregnancy: Category B (US FDA). Can be used during labor. Crosses the placenta. May cause transient fetal bradycardia. Use during pregnancy only if clearly needed. Avoid prolonged use; can cause neonatal opioid withdrawal syndrome (NOWS) if used chronically.
Driving: IMPAIRED ABILITY. Causes significant drowsiness, dizziness, and blurred vision. Patients must NOT drive or operate heavy machinery for at least 6-8 hours after a dose or until clear of effects.
| Other CNS Depressants (e.g., Alcohol, Benzodiazepines, Barbiturates, Sedative Antihistamines) | Additive CNS depression, profound sedation, respiratory depression, hypotension, coma, or death. | Major |
| Pure Mu-Opioid Agonists (e.g., Morphine, Fentanyl, Pethidine) | Nalbuphine may antagonize the analgesic and respiratory depressant effects of pure agonists. May precipitate withdrawal in physically dependent patients. | Major |
| Monoamine Oxidase Inhibitors (MAOIs) e.g., Phenelzine, Selegiline | Risk of serotonin syndrome or exaggerated opioid effects (coma, severe respiratory depression). | Major |
| Mixed Agonist-Antagonists (e.g., Pentazocine, Butorphanol) | May reduce analgesic effect of nalbuphine and/or precipitate withdrawal symptoms. | Moderate |
| Anticholinergic Drugs | Increased risk of urinary retention and severe constipation. | Moderate |