Morphine Equivalent Dose for Nubain (Nalbuphine) 10 mg IV
Nubain (nalbuphine) 10 mg IV is approximately equivalent to 10 mg of IV morphine, using a 1:1 potency ratio.
Equianalgesic Conversion
- Nalbuphine and morphine demonstrate roughly equivalent potency when comparing gastrointestinal effects and analgesic properties at equal milligram doses 1
- In a controlled study examining gastric emptying and small bowel transit times, nalbuphine 10 mg produced effects similar to morphine 5 mg, while nalbuphine 5 mg had effects approximately equal to morphine 5 mg, suggesting the potency ratio of nalbuphine appears roughly equivalent to morphine on a milligram-per-milligram basis 1
- For practical clinical conversion, use a 1:1 ratio: 10 mg IV nalbuphine = 10 mg IV morphine 1
Important Clinical Considerations
Key Pharmacological Differences
- Nalbuphine is a mixed agonist-antagonist opioid, not a pure mu-opioid agonist like morphine, which means it has a ceiling effect for respiratory depression and may precipitate withdrawal in opioid-dependent patients 2
- The National Comprehensive Cancer Network recommends avoiding mixed agonist-antagonist opioids in combination with pure agonists as this could precipitate withdrawal in opioid-dependent patients 3
Onset and Duration
- IV morphine has peak effects within 15-30 minutes after administration with a duration of action of approximately 4 hours 4
- A 10 mg bolus dose of IV morphine provides rapid onset of analgesic effect (approximately 5 minutes) when given to patients with moderate pain 5
Safety Profile
- A 10 mg bolus dose of IV morphine given to patients with moderate pain does not cause severe respiratory depression and is well tolerated if there is a certain level of pain at administration 5
- IV morphine 10 mg may cause a slight but significant increase in PaCO2 (approximately 5.2-5.5 kPa) within the first 15 minutes, along with mild sedation 5
Common Pitfall to Avoid
Do not assume nalbuphine can be freely substituted for morphine in all clinical scenarios. While the analgesic potency may be similar at equianalgesic doses, nalbuphine's mixed agonist-antagonist properties make it fundamentally different from pure mu-agonists like morphine, particularly in patients already receiving opioid therapy 2, 3.