Is Penbutolol safe while breastfeeding?

Summary of use during breastfeeding

Penbutolol is not marketed in the United States. Based on its physicochemical properties, penbutolol appears to present a low-risk to the breastfed infant. Because there is no published experience with penbutolol during breastfeeding, other agents may be preferred, especially while nursing a newborn or preterm infant.

Effects on the breastfed infant

Relevant published information on penbutolol was not found as of the revision date. A study of mothers taking beta-blockers during nursing found a numerically, but not statistically significant increased number of adverse reactions in those taking any beta-blocker. Although the ages of infants were matched to control infants, the ages of the affected infants were not stated. None of the mothers were taking penbutolol.[2]

Effects on milk supply

Relevant published information on the effects of beta-blockade or penbutolol during normal lactation was not found as of the revision date. A study in 6 patients with hyperprolactinemia and galactorrhea found no changes in serum prolactin levels following beta-adrenergic blockade with propranolol.[3]

Levels in milk

The excretion of beta-adrenergic blocking drugs into breastmilk is largely determined by their protein binding. Those with low binding are more extensively excreted into breastmilk.[1] Accumulation of the drugs in the infant is related to the fraction excreted in urine. With 80 to 90% protein binding, 5% renal excretion and a moderate half-life, penbutolol presents a low risk for accumulation in infants.

Maternal Levels. Relevant published information was not found as of the revision date.

Infant Levels. Relevant published information was not found as of the revision date.

Alternatives LactMed lists

• Propranolol
• Labetalol
• Metoprolol