This drug is related to serious side effects in some babies. By this reason If a nursing mother needs acebutolol, caution should be used, specially on preterm or very young babies.
Acebutolol and diacetolol, his active metabolite, are extensively excreted into breastmilk. A fully breastfed infant would receive about 3.5% of the maternal weight-adjusted dosage of acebutolol. If is needed a beta-blocker, the best choice is an alternate drug, especially in first 60 days of life.
Has been published a case report of hypotension, bradycardia, and tachypnea in a newborn infant, probably because of acebutolol (and diacetolol) in breastmilk.
Warning of the manufacturer:
Acebutolol and its active metabolite are excreted in breast milk and the half-life of acebutolol in the neonate is double that in adult. Have not been assessed adequately the risks of hypoglycaemia and bradycardia in the nursing infant. Therefore, breast-feeding is not recommended during treatment.