From the Guidelines
Metoprolol is considered compatible with breastfeeding at standard therapeutic doses, with a recommended dose during lactation of 25-100 mg twice daily for immediate-release formulations or 50-200 mg once daily for extended-release formulations, depending on the condition being treated and individual response. The decision to use metoprolol during lactation is supported by its relatively low risk of adverse effects on the infant, as indicated by a limited amount of data suggesting it is likely low risk 1. Although there is limited safety data available for metoprolol tartrate, its use is considered likely low risk, similar to other beta-blockers like labetalol, which has a relative infant dose (RID) of 3.6% 1.
When initiating metoprolol therapy in lactating women, it is essential to start at the lower end of the dosing range and titrate as needed for blood pressure or heart rate control. Monitoring the breastfed infant for potential side effects such as bradycardia, hypotension, or lethargy is crucial, although these are rarely reported 1. If possible, timing the medication doses so that peak blood levels occur after breastfeeding sessions can help minimize infant exposure.
The choice of metoprolol over other beta-blockers during lactation may be influenced by its pharmacokinetic properties, including a relatively short half-life and limited milk transfer. However, the primary consideration should always be the balance between the therapeutic benefits of metoprolol for the mother and the potential risks to the breastfed infant. Given the current evidence, metoprolol appears to be a reasonable option for lactating women who require beta-blocker therapy, with careful monitoring and dose adjustment as needed to ensure both maternal and infant well-being.
From the FDA Drug Label
Metoprolol is excreted in breast milk in a very small quantity. An infant consuming 1 liter of breast milk daily would receive a dose of less than 1 mg of the drug
The recommended dose of metoprolol during lactation is not explicitly stated in the drug label. However, it is mentioned that metoprolol is excreted in breast milk in a very small quantity, with an infant consuming 1 liter of breast milk daily receiving a dose of less than 1 mg of the drug 2.
- Key points:
- Metoprolol is excreted in breast milk in small quantities.
- The dose received by an infant through breast milk is less than 1 mg per liter of breast milk consumed. No specific dose recommendation for metoprolol during lactation can be made based on the provided information.
From the Research
Metoprolol Dose in Lactation
- The recommended dose of metoprolol during lactation is not explicitly stated in the provided studies, but we can look at the pharmacokinetics of metoprolol during lactation to inform our understanding.
- A study published in the Journal of Clinical Pharmacology 3 found that the relative infant exposure to metoprolol through breast milk was <1.0% of maternal weight-adjusted dose, suggesting that metoprolol is relatively safe during lactation.
- However, the same study noted that metoprolol apparent oral clearance was significantly higher during mid- and late pregnancy compared to postpartum, which may affect the dose required during lactation.
- Another study published in the European Journal of Clinical Pharmacology 4 found that the apparent oral clearance of metoprolol was 4.4 times higher during pregnancy than after pregnancy, which may also impact the dose required during lactation.
- It's worth noting that the studies provided do not offer a specific dose recommendation for metoprolol during lactation, and the dosing may need to be individualized based on the patient's response and clinical circumstances.
Factors Affecting Metoprolol Dose
- A study published in Pharmacoepidemiology and Drug Safety 5 found that women are often started on a lower daily dose of metoprolol than men, despite non-sex specific guideline recommendations.
- The study suggests that this difference in dosing may be a potential source of confounding by contraindication in pharmacoepidemiology.
- However, this study does not provide specific guidance on metoprolol dosing during lactation.
Clinical Considerations
- A study published in the Journal of Clinical Pharmacology 3 suggests that clinicians who prescribe metoprolol during pregnancy should be prepared to make aggressive changes in dosage (dose and frequency) or consider using an alternate beta-blocker if inadequate clinical responses are encountered.
- This may also be relevant during lactation, although the specific dosing recommendations are not provided.