• Metabolism: Half Life: The plasma half-life of nalbuphine is 5 hours, and in clinical studies the duration of analgesic activity has been reported to range from 3 to 6 hours.
• Uses/Sources: Nalbuphine is indicated for the relief of moderate to severe pain. It can also be used as a supplement to balanced anesthesia, for preoperative and postoperative analgesia, and for obstetrical analgesia during labor and delivery. [Wikipedia]
• Health Effects: Medical problems can include congested lungs, liver disease, tetanus, infection of the heart valves, skin abscesses, anemia and pneumonia. Death can occur from overdose.
• Symptoms: Symptoms of overdose include primarily sleepiness and mild dysphoria.
• Treatment: The immediate intravenous administration an opiate antagonist such as naloxone or nalmefene is a specific antidote. Oxygen, intravenous fluids, vasopressors and other supportive measures should be used as indicated. (L1712)
• Route of Exposure: Intravenous. The mean absolute bioavailability was 81% and 83% for the 10 and 20 mg intramuscular doses, respectively, and 79% and 76% following 10 and 20 mg of subcutaneous nalbuphine.

• Carcinogenicity: No indication of carcinogenicity to humans (not listed by IARC).
• Toxicity: LD50: 1100 mg/kg (Oral, Dog) (A308)

Receptor studies show that nalbuphine exerts its action via binding to mu, kappa, and delta receptors, but not to sigma receptors. Nalbuphine is primarily a kappa agonist/partial mu antagonist analgesic. The exact mechanism of action is unknown, but is believed to interact with an opiate receptor site in the CNS (probably in or associated with the limbic system). The opiate antagonistic effect may result from competitive inhibition at the opiate receptor, but may also be a result of other mechanisms. Nalbuphine is thought primarily to be a kappa agonist. It is also a partial mu antagonist analgesic, with some binding to the delta receptor and minimal agonist activity at the sigma receptor.