What are the effects of naltrexone on blood pressure in a breastfeeding woman with a history of substance use disorder?

Naltrexone and Blood Pressure

Naltrexone does not have clinically significant direct effects on blood pressure in most patients, though monitoring is recommended when used in combination formulations (particularly naltrexone-bupropion), which can elevate blood pressure and heart rate. 1, 2

Direct Effects of Naltrexone Monotherapy

• Naltrexone as a standalone medication for opioid use disorder has not been associated with significant blood pressure changes in clinical trials 3, 4
• The FDA label for naltrexone does not list hypertension or blood pressure elevation as a common adverse effect when used at standard doses (50 mg/day for opioid use disorder) 3
• In studies of naltrexone for substance use disorders, cardiovascular effects reported were limited to non-specific findings such as palpitations and tachycardia in less than 1% of subjects, with no consistent pattern of blood pressure elevation 3

Combination Formulations: Naltrexone-Bupropion

When naltrexone is combined with bupropion (as in naltrexone-bupropion ER for weight management), blood pressure monitoring becomes essential because bupropion can elevate both blood pressure and heart rate. 1, 2

• The American Heart Association recommends monitoring blood pressure and heart rate periodically during treatment with naltrexone-bupropion, especially in the first 12 weeks 1
• Uncontrolled hypertension is a contraindication to naltrexone-bupropion use 1, 2
• The blood pressure effects are attributable to the bupropion component, not naltrexone 1

Special Considerations for Breastfeeding Women with Substance Use Disorder

Naltrexone-bupropion ER is explicitly contraindicated during breastfeeding. 2

• The American College of Obstetricians and Gynecologists states that naltrexone-bupropion ER is contraindicated in breastfeeding women 2
• Bupropion is present in breast milk at low levels, and two case reports of seizures in breastfed infants warrant caution 1
• For breastfeeding women requiring treatment for opioid use disorder, methadone or buprenorphine (not naltrexone) are the recommended first-line medication-assisted treatments 5

Naltrexone Monotherapy in Pregnancy and Lactation

• While naltrexone has been studied in pregnancy with promising results (no increase in neonatal abstinence syndrome when maintained to delivery), data on its use during breastfeeding specifically are insufficient 6
• The Society for Maternal-Fetal Medicine notes that data are insufficient to recommend naltrexone for opioid use disorder treatment during pregnancy, though recent research suggests it may be viable for select patients who completely detoxify 5, 6
• Naltrexone crosses the placenta with concordant maternal-fetal levels and clears quickly from maternal circulation 6

Monitoring Recommendations

For any patient on naltrexone-containing medications, particularly combination products:

• Monitor blood pressure before initiating treatment and periodically during therapy, especially in the first 12 weeks 1
• The American College of Gastroenterology recommends surveillance of liver function tests every 3 to 6 months for patients on long-term naltrexone treatment 7
• Close monitoring (every 2-4 weeks) is necessary when using doses higher than 50 mg/day, as hepatotoxicity risk increases with supratherapeutic doses 7

Critical Clinical Pitfalls

• Do not confuse naltrexone monotherapy effects with naltrexone-bupropion combination effects – the blood pressure concerns are primarily related to the bupropion component 1
• Avoid naltrexone-bupropion in breastfeeding women – this is an absolute contraindication 2
• For breastfeeding women with opioid use disorder, prioritize methadone or buprenorphine over naltrexone, as these have more established safety profiles and efficacy data 5
• Ensure complete opioid detoxification before initiating naltrexone to avoid precipitated withdrawal, which can cause cardiovascular stress including tachycardia and blood pressure fluctuations 3, 8