Amiodarone Pregnancy and Breastfeeding Warnings
Amiodarone Pregnancy Warnings
Amiodarone has been assigned to pregnancy category D by the FDA. Animal studies have revealed evidence of embryotoxicity. There are no data from controlled human pregnancy studies. Amiodarone should only be given during pregnancy when there are no alternatives and benefit outweighs risk.
Amiodarone and its metabolite cross the human placenta. The average umbilical cord to maternal plasma drug concentration ratio ranges from 0.1 to 0.6. While there are numerous reports describing the safety of amiodarone during pregnancy, some reports of congenital goiter, hypothyroidism and hyperthyroidism, fetal bradycardia, and growth or psychomotor retardation have also been reported. A single case of congenital hypothyroidism with goiter, hypotonia, bradycardia, enlarged fontanels, macroglossia, immature bone age, and psychomotor retardation has been reported in a neonate whose mother was taking amiodarone 200 mg per day from gestation week 13 through delivery at week 38. The infant's plasma amiodarone and desethylamiodarone concentrations averaged 0.14 and 0.26 mcg per mL, respectively, five days postpartum. In three case reports of human pregnancies in which amiodarone was given throughout gestation, one major and two minor congenital anomalies were observed. The major defect was a large muscular ventricular septal defect associated with congestive heart failure in a premature (35 weeks) neonate whose mother was receiving amiodarone 200 mg per day. The infant also had an umbilical hernia (considered minor). The mother's amiodarone and desethylamiodarone levels were 1.26 and 1.72 mcg per mL, respectively, at steady state. The other minor defect was bradycardia in a euthyroid infant that was delivered by a woman who was receiving amiodarone 600 mg per day. The third pregnancy was electively terminated, but was normal for gestational age. Because of these reports and the limited experience with amiodarone during pregnancy, two expert reviews of the use of amiodarone during pregnancy recommend that amiodarone be restricted to refractory cases of maternal or fetal tachyarrhythmias. Avoidance of amiodarone during pregnancy in a woman already taking the drug necessitates stopping therapy several months before conception due to its prolonged elimination half-life. It is recommended that neonates whose mothers received amiodarone have complete thyroid function tests performed because of the iodine burden introduced by amiodarone. Furthermore, it is recommended that fetal echocardiography be considered in all pregnancies exposed to amiodarone in the embryonic period.
Amiodarone Breastfeeding Warnings
Data reveal the average milk to maternal serum amiodarone concentration ratio varies greatly, ranging from 1.7 to 13. One case in which a mother was taking amiodarone 200 mg per day, milk amiodarone and desethylamiodarone levels ranged from 0.5 to 1.8 mcg per mL and 0.4 to 0.8 mcg per mL, respectively. Another case in which a mother was taking 400 mg per day, levels were up to nine times higher. These data indicate there is a significant drug and iodine exposure to the nursing infant.
Amiodarone is excreted into human milk. Adverse effects in nursing infants have not been reported. Because of the significant concentration of amiodarone in human milk, the prolonged elimination half-life, and the significant iodine burden amiodarone poses to the nursing infant, breast-feeding should not be initiated or should not be continued by a woman receiving amiodarone.
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