Propranolol reaches low levels in human milk, so the possible amount of drug ingested by the infant may be considered irrelevant. The pharmacokinetic profile of propranolol predicts this low level, since its plasma protein binding is high (87%) and renal excretion is low, being less than 1%.The urinary excretion correlates well with the accumulation of the substance in the infant. In this case, is illustrative of the low risk of influence of propranolol on breastfed babies.
Confirming the above, pharmacokinetic studies have shown that drug quantities transferred to the child are negligible. It is estimated that an exclusively breastfed baby could receive an amount of less than 0.1% and maximum of 0.9% of the maternal dose weight-adjusted of propranolol.
The administration of propranolol to the nursing mother does not require special precautions and is considered compatible with breastfeeding.
Warning of the manufacturer:
Most beta blockers, particularly lipophilic, are passing to the breast milk though varying concentration from one to other. Therefore, breastfeeding is not advised after administration of these drugs.