What are the contraindications of Nubain (nalbuphine) in pregnancy?

Contraindications of Nubain (Nalbuphine) in Pregnancy

Nubain (nalbuphine) is contraindicated in pregnant women with opioid use disorder (OUD) or those on medication-assisted treatment (MAT) with methadone or buprenorphine, as it can precipitate acute opioid withdrawal in both mother and fetus. 1

Absolute Contraindication: Opioid-Dependent Patients

Opioid agonist/antagonists such as nalbuphine must be avoided in pregnant women with OUD or chronic opioid therapy because they can trigger severe withdrawal. 1 This applies to:

• Women receiving methadone maintenance therapy 1
• Women on buprenorphine treatment 1
• Women taking chronic opioids for pain management 1

The mechanism involves nalbuphine's mixed agonist-antagonist properties at opioid receptors, which can displace full agonists and precipitate withdrawal symptoms that are harmful or potentially fatal to both mother and fetus. 1

Clinical Context for Use in Non-Opioid-Dependent Patients

When opioid dependence is absent, nalbuphine has been used as an obstetric analgesic during labor, though important caveats exist:

Fetal Effects

• Nalbuphine crosses the placenta readily, with newborn concentrations ranging from one-third to six times the maternal concentration 2
• Sinusoidal fetal heart rate patterns have been documented after nalbuphine administration, which can be concerning for fetal well-being 3
• Transient depressive effects on the fetal/neonatal central nervous system are possible 4

Neonatal Considerations

• Respiratory depression in the neonate can occur, similar to other opioids 3
• Apgar scores and umbilical venous pH should be monitored 4
• The drug has a terminal elimination half-life of 2.4 hours in the mother 2

Breastfeeding

• Nalbuphine excretion in breast milk is minimal (0.012% of maternal dose over 24 hours) 5
• Adverse opioid reactions in breastfed neonates are not expected 5

Critical Screening Algorithm

Before administering nalbuphine during pregnancy or labor:

1. Obtain detailed substance use history including prescription opioids, illicit opioids, and MAT 1
2. Perform urine toxicology screening to identify undisclosed opioid use 1
3. Verify absence of chronic opioid therapy for pain management 1
4. Confirm patient is not on methadone or buprenorphine maintenance 1

Common Pitfall

The most dangerous error is administering nalbuphine to a woman with unrecognized opioid dependence. Even women not formally enrolled in MAT programs may be using opioids regularly, and nalbuphine administration can precipitate acute withdrawal with serious maternal and fetal consequences. 1 Always screen for substance use before administering mixed agonist-antagonist opioids.