Nalbuphine Hydrochloride Injection 10 mg/mL (Pfizer)

Nalbuphine hydrochloride is a synthetic opioid analgesic (an agonist–antagonist) and a prescription-only medication. This product is supplied as a sterile, preservative-free aqueous solution in 1 mL glass ampules, each containing 10 mg of nalbuphine (label strength 10 mg/mL). (Pfizer distributes it via Hospira; one common brand name was Nubain.) It is intended for parenteral use only (intravenous, intramuscular or subcutaneous injection), not for oral or topical use. Each ampule is single-use (single-dose) and must be discarded after opening; it does not contain any added preservatives.

Mechanism of Action and Analgesic Effects

Nalbuphine is a mixed opioid agonist–antagonist. It acts as a kappa-receptor agonist and a mu-receptor antagonist. This gives it potent pain-relieving effects (analgesia) with some differences from classic opioids. On a milligram-for-milligram basis, nalbuphine’s analgesic potency is roughly equivalent to morphine for doses up to about 30 mg. It produces the typical opioid effects of pain relief, sedation and respiratory depression, but it has certain unique features: it tends to cause less euphoria (since it blocks mu receptors) and exhibits a “ceiling effect” on respiratory depression – doses above about 30 mg do not cause proportionally more breathing suppression. Like other opioids, its analgesic effect begins rapidly (within 2–3 minutes after IV injection, less than 15 minutes after IM/SC) and lasts on the order of 3–6 hours.

Uses

Nalbuphine injection is indicated for moderate to severe pain when opioid analgesia is needed and other treatments are inadequate. It is commonly used:

• Pain management: as a parenteral analgesic in hospitals (e.g. for postoperative pain, trauma pain, or chronic pain) when non-opioid measures fail.
• Anesthesia adjunct: during surgery as part of balanced anesthesia protocols (supplement to general anesthesia) due to its analgesic and sedative properties (often given IV over 10–15 minutes in larger doses for anesthesia; maintenance dosing is then given as needed).
• Obstetrical analgesia: it can be used for labor analgesia (pain relief during childbirth), though use in pregnancy/labor requires caution (see Precautions).

Note: Nalbuphine should only be used when clearly needed and under medical supervision. It should not be given for mild pain or as a routine sedative. It is a prescription drug (Rx only), not available without a doctor’s order.

Dosage and Administration

Typical adult dosing: For most adults, the usual starting dose is 10 mg (i.e. 1 mL from one ampule) given IM, SC, or slowly IV, then titrated as needed. This dose can be repeated every 3–6 hours for pain control. Titrate slowly: use the lowest effective dose to balance pain relief against side effects. In patients not already tolerant to opioids, the max single dose is generally around 20 mg, with a maximum total daily dose of about 160 mg. (Higher doses may be used when managing anesthesia, as noted above. No adjustment is typically needed for mild renal or hepatic impairment, but use caution and monitor if organ function is poor.

Administration notes: Always inspect the solution visually – it should be clear, colorless (or slightly yellow) and free of particles before injection. Use aseptic technique. Ampules are single-dose; discard unused portion. Nalbuphine can be given by slow IV push (over several minutes), or by deep IM/SC injection. Do not administer orally. (It is not approved for epidural or intrathecal injection; only give by standard parenteral routes.)

Pharmacokinetics

After IV dosing, nalbuphine onset is rapid (analgesia in ~2–3 minutes) and duration ~3–6 hours. After IM or SC dosing, onset is usually within 15 minutes. Its plasma half-life is about 5 hours. Nalbuphine is metabolized (likely in liver) and eliminated via urine and feces. Small amounts of parent drug and metabolites may cross the placenta or into breast milk.

Side Effects and Precautions

Like all opioids, nalbuphine can cause serious side effects. The most common adverse effect is sedation or drowsiness – in clinical studies about one-third of patients experienced significant sedation. Patients often feel lightheaded, dizzy or sleepy. Other frequent reactions include sweating, nausea, vomiting, headache, and dry mouth. Nalbuphine often causes pruritus (itching) or skin flushing in sensitive individuals (it can actually reverse opioid-induced itching). Respiratory depression (slowed, shallow breathing) is a dangerous potential effect, especially if doses are too high or given with other sedating drugs. Because of its kappa-agonist action, nalbuphine can also produce dysphoria or mood changes (unlike the euphoria of pure mu-agonists) – some patients report hallucinations, confusion, or unpleasant dreams.

Important precautions:

• Respiratory depression: This is the most serious risk. Nalbuphine can cause respiratory arrest, particularly when starting therapy or after dose increases. Monitor breathing closely (e.g. pulse oximetry) during initiation and titration. Have oxygen and resuscitation equipment available.
• Drug interactions: Concomitant use with other CNS depressants (e.g. benzodiazepines, alcohol, sleeping pills, antipsychotics, other opioids) can greatly intensify sedation and respiratory depression. Avoid or minimize such combinations.
• Opioid dependent patients: Because nalbuphine is a mu-opioid antagonist, giving it to someone physically dependent on mu-agonist opioids (like morphine, oxycodone) can precipitate acute withdrawal (agitation, sweating, nausea, etc.). Use extreme caution if switching an opioid-tolerant patient to nalbuphine.
• Pregnancy and labor: Nalbuphine crosses the placenta. It may cause neonatal respiratory depression and/or fetal heart rate changes if given during labor. Use only if clearly needed and never habitually. Infants should be monitored if mother received nalbuphine during childbirth. It is not recommended for chronic use in pregnancy or while nursing.
• Respiratory conditions: Do not give nalbuphine to patients with significant respiratory depression, acute or severe asthma, or hypercapnia. Avoid use in unmonitored settings.
• Gastrointestinal: Like other opioids, nalbuphine can cause constipation and aggravate conditions like paralytic ileus. It is contraindicated if a patient has known or suspected GI obstruction.
• Head injury/neurological: Avoid in patients with head injuries or raised intracranial pressure: opioid-induced CO₂ retention may further raise intracranial pressure.
• Hypotension: Nalbuphine may cause vasodilation and hypotension, especially in hypovolemic patients. Use with caution in patients with cardiac disease or on blood pressure medications.

Abuse potential: Nalbuphine is an opioid, but because it has mixed agonist–antagonist activity, it tends to have lower abuse potential than pure mu agonists. It is not classified as a controlled substance under U.S. federal law. However, it can still be misused or cause dependence. Use it only in patients where the benefits outweigh the risks. Warn patients against sharing or taking extra doses.

Storage and Handling

Store nalbuphine ampules at controlled room temperature (20–25 °C [68–77 °F]). Keep the solution in its original carton until use (the carton shields it from light). Protect from excessive light. Do not freeze. Since ampules are single-dose, do not save opened or partially used ampules. Dispose of any unused ampule or solution per medical waste regulations. Keep out of reach of children and pets (ingestion can be fatal).

Packaging (Label)

This Pfizer product comes as colorless glass ampules (often packaged 10 per tray) of 1 mL each, labeled “Nalbuphine Hydrochloride Injection 10 mg/mL – Rx only.” There are no added preservatives or latex. Ampules are typically in trays of 10, with each amp containing sterile, buffered solution (pH ~3.7). The package is labeled for single-use only, and the solution must be used under medical supervision only.

Summary: Nalbuphine HCl 10 mg/mL in 1 mL ampules is a potent opioid analgesic for injection. It provides rapid pain relief similar to morphine but with a mixed agonist–antagonist profile It is used by healthcare providers (IV/IM/SC) to treat moderate-to-severe pain, as an anesthetic adjunct, and sometimes for labor analgesia. Because of the serious risks (respiratory depression, sedation, withdrawal, etc.), it must be used cautiously with precise dosing, under close monitoring. Fully understanding its pharmacology, proper dosing, and the patient’s conditions is essential to using nalbuphine safely and effectively.