Amiodarone is metabolized to desethylamiodarone a pharmacologically active substance, so that potential adverse effects are the sum of both products. Must consider not only the effects on the heart, but of iodinated substances because it can release a significant amount of iodine during the metabolism of amiodarone. It is estimated that for each 100 mg of amiodarone administered to the mother is released 6 mg of iodine.
The concentration of the drug and its metabolite in human milk and baby's blood can be high, and may have toxic effects on heart or thyroid gland, as has been reported previously. Should be noted that the impact of the taking of amiodarone can last up to several weeks after discontinuation of treatment, due to the long half life of the drug, more than three months in adult subjects.
It is considered that an exclusively breastfed infant may receive a dose between 3 and 45% of the maternal dose, including the fraction corresponding to desethylamiodarone, with an average dose of 11% of the amount given to the mother, that can reach levels between 14 and 74% of this. There may be signs of hypothyroidism during the neonatal period, which in part could be due to transplacental passage rather than breastfeeding itself.
Warning of the manufacturer:
Due to amiodarone pass into breast milk in significant quantities and the iodine content of this drug, its administration is contraindicated during lactation.