RUBUPHINE 20 mg

Indications

• Moderate to severe pain management
• Postoperative pain relief
• Labor analgesia

Dosage

Children: For paediatric patients, nalbuphine should be dosed based on weight and clinical judgment. Refer to the BNF for Children for specific

Adults: The typical adult dosage of nalbuphine for pain management ranges from 10 to 20 mg administered intravenously or intramuscularly every 3 to 6 hours as needed, not to exceed 160 mg per day.

Mechanism of action

The exact mechanism of action of nalbuphine is unknown, but it is believed to interact with opiate receptor sites in the central nervous system, likely in or associated with the limbic system. It acts primarily as a kappa receptor agonist and exhibits partial agonist activity at mu receptors, while also having minimal activity at delta and sigma receptors. This mechanism may result in both analgesic effects and opioid antagonist activity, particularly in the presence of full mu agonists.

Pharmacodynamics

Nalbuphine has analgesic potency comparable to that of morphine on a milligram basis. Its opioid antagonist activity is significantly lower than that of nalorphine and pentazocine, but it has the capacity to block or reverse opioid-induced respiratory depression when used alongside mu agonist opioids. Nalbuphine may induce withdrawal symptoms in patients with opioid dependence, thus necessitating careful use in such populations.

Pharmacokinetics

Nalbuphine is administered via various routes, including intravenous, intramuscular, and subcutaneous injections. It is rapidly absorbed, with peak plasma concentrations generally occurring within an hour. The drug is metabolized primarily in the liver and excreted in urine, with a half-life that allows for effective pain management over a defined period. Its pharmacokinetics can be influenced by individual patient factors, including liver function and concurrent medications.

Contra-indications

• Hypersensitivity to nalbuphine or any of its components
• Patients with known or suspected gastrointestinal obstruction
• Acute or severe bronchial asthma or hypercapnia
• Concurrent use with other opioid agonists

Adverse effects

• Nausea
• Vomiting
• Sedation
• Constipation
• Dizziness
• Headache
• Respiratory depression
• Withdrawal symptoms in opioid-dependent patients

Interactions

• Concomitant use with other central nervous system depressants may increase the risk of respiratory depression
• Opioid agonists may have their effects reversed by nalbuphine
• Caution is advised when administered with other medications that can affect respiratory function

Precautions

• Use with caution in patients with a history of substance use disorder
• Monitor for signs of respiratory depression, especially in the elderly or those with respiratory conditions
• Adjust dosing in patients with hepatic or renal impairment

Pregnancy

Nalbuphine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. It is classified as Category C.

Breast-feeding

Nalbuphine is excreted in breast milk, and caution should be exercised when administering to nursing mothers.

Storage

Store at room temperature, away from moisture and heat. Keep out of reach of children.

Formulations

• Injectable solution

Mechanism of action

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.

Pharmacodynamics

Nalbuphine is a synthetic opioid agonist-antagonist analgesic of the phenanthrene series. Nalbuphine's analgesic potency is essentially equivalent to that of [morphine] on a milligram basis. The opoioid antagonist activity of nalbuphine is about one-fourth to that of [nalorphine] and 10 times to that of [pentazocine]. Nalbuphine by itself has potent opioid antagonist activity at doses equal to or lower than its analgesic dose. When administered following or concurrent with mu agonist opioid analgesics (e.g., morphine, oxymorphone, fentanyl), nalbuphine may partially reverse or block opioid-induced respiratory depression from the mu agonist analgesic. Nalbuphine may precipitate withdrawal in patients dependent on opioid drugs. Nalbuphine should be used with caution in patients who have been receiving mu opioid analgesics on a regular basis.