Can you take amiodarone while breastfeeding?

How much amiodarone gets into breastmilk

Amiodarone is an iodine-containing compound that is active and is also metabolized to the active metabolite desethylamiodarone. Metabolism also releases 6 mg of free iodine for each 100 mg of amiodarone which can affect thyroid function. The drug has an exceptionally long half-life of 100 days in adults because of extensive storage in body fat. It requires weeks to months to attain steady state and to be cleared from the body.

Maternal Levels. After having taken amiodarone 200 mg twice daily 5 days weekly for 4 years, the milk of a mother was completely expressed 4 times during the first 2 days postpartum. The average milk amiodarone concentration was 3.5 mg/L. The authors calculated that her infant would have received an average of 18% and a maximum of 26% of the maternal weight-adjusted dosage of amiodarone.

A woman who took amiodarone with reducing doses of 600, 400 and 200 mg daily for one week at each dosage level during the last 3 weeks of pregnancy had milk amiodarone and desethylamiodarone levels of 0.5 to 1.8 mg/L and 0.4 to 0.8 mg/L, respectively, in 5 samples of colostrum obtained during days 2 and 3 postpartum.

In a mother who took amiodarone 200 mg daily for the last 5 weeks of pregnancy and for one week after delivery, milk amiodarone and desethylamiodarone levels were 0.55 and 0.44 mg/L, respectively, at 4 weeks postpartum and 0.030 and 0.002 mg/L at 6 weeks postpartum.

A mother who took amiodarone 200 mg daily throughout pregnancy and during breastfeeding had milk amiodarone and desethylamiodarone levels of 1.7 and 0.75 mg/L, respectively, 2 weeks postpartum and 3.0 and 1.8 mg/L 3 weeks postpartum.

Another mother who took amiodarone 200 mg daily throughout pregnancy had milk amiodarone and desethylamiodarone levels of 2.2 and 0.77 mg/L, respectively, at birth. Her infant was breastfed, but no infant serum levels were measured.

A woman who took amiodarone 400 mg daily from week 14 of pregnancy and throughout nursing had milk amiodarone levels that varied from 1.06 to 3.65 mg/L (average 2.52 mg/L) and milk desethylamiodarone levels that varied from 0.5 to 1.24 mg/L (average 0.9 mg/L) on 5 occasions during the month following delivery. Her breastfed infant's thyroid function tests remained normal.

A woman who took amiodarone 800 mg daily for 1 week starting at week 34 of pregnancy, then 400 mg daily for the rest of her pregnancy and during breastfeeding had milk amiodarone levels that varied from 3.6 to 14.4 mg/L (average 10.4 mg/L) and milk desethylamiodarone levels that varied from 1.3 to 5.7 mg/L (average 4.1 mg/L) on days 9, 11 and 13 postpartum.

A woman took amiodarone 200 mg three times daily for 11 days, then 200 mg twice daily during her pregnancy. She discontinued the drug at the time of delivery and breastfed her infant. The milk amiodarone level was 0.6 mg/L on day 5 and increased to 2.1 mg/L on day 11. The increase between days 5 and 11 could have been due to sampling times (fore- vs hindmilk) or because of an increase in fat content as lactation progressed. Amiodarone was undetectable in milk by day 25.

A postpartum woman was given a single intravenous dose of amiodarone 450 mg for a tachyarrhythmia. Milk samples were collected 3, 4 and 10 days after the dose. At 3 days after the dose, the milk amiodarone concentration was about 185 mcg/L. On day 4, the milk concentration was 233 mcg/L and on day 10, it had fallen to 132 mcg/L. Desethylamiodarone concentrations were not reported. The author estimated that the amiodarone dose that a fully breastfed infant would receive would be 35 mcg/kg daily, which represents a maximum of 0.18% of the pediatric dosage or 0.6% of the weight-adjusted dose maternal dose.

A woman with peripartum cardiomyopathy and severe nonsustained ventricular tachycardia gave birth to twins. Amiodarone was initiated on the second day after birth, initially intravenously, then orally and by intravenous drip until day 4 after birth for a total dosage of 1087 mg intravenously and 400 mg by mouth over the 4 days. Bisoprolol, edoxaban, vonoprazan, febuxostat, imidapril, and pitavastatin were also started postpartum. Two milk samples were collected at 14 and 39 days after the end of amiodarone therapy. On day 14, milk concentrations of amiodarone and its active metabolite mono-N-desethylamiodarone were 111 mcg/L and 143 mcg/L, respectively. On day 39, milk concentrations of amiodarone and its active metabolite mono-N-desethylamiodarone were 118 mcg/L and 36.6 mcg/L, respectively. From these points, the authors estimated the half-lives of amiodarone and mono-N-desethylamiodarone in breastmilk to be 7.8 and 12.6 days, respectively.

Infant Levels. A mother took amiodarone 200 mg daily throughout pregnancy and during breastfeeding. Her breastfed infant had serum amiodarone and desethylamiodarone levels of 30 and 320 mcg/L (4.5 and 51% of maternal plasma levels), respectively, at 3 weeks postpartum.

A mother took amiodarone 200 mg daily for the last 5 weeks of pregnancy and for one week after delivery. At 4 weeks postpartum, the breastfed infant's plasma amiodarone and desethylamiodarone levels were 10 and 160 mcg/L, respectively. At 6 weeks postpartum, her breastfed infant's drug and metabolite plasma levels were 10 and 30 mcg/L.

A woman took amiodarone 400 mg daily from week 14 of pregnancy and throughout nursing. Her breastfed infant's serum amiodarone and desethylamiodarone levels were 200 and 50 mcg/L (60% and 14% of maternal levels), respectively, at one day of age and undetectable (<100 and <50 mcg/L, respectively) at 1 and 2 weeks of age.

A woman took amiodarone 800 mg daily for 1 week starting at week 34 of pregnancy, then 400 mg daily for the rest of her pregnancy and during breastfeeding. Her breastfed infant's serum amiodarone level remained constant at 400 mcg/L (about 25% of maternal serum levels) during the first 9 weeks of life, while desethylamiodarone levels slowly decreased from 0.3 (22% of maternal serum levels) to 150 mcg/L (10% of maternal serum levels) during the same time period.

One group reported amiodarone breastmilk levels in 2 patients. The first mother received a total of 7.6 grams of amiodarone over the first 7 days postpartum for ventricular tachycardia and ventricular fibrillation. She collected breastmilk samples between days 10 and 18 postpartum. Back-extrapolation of the sample values indicated an initial amiodarone concentration of 24.8 mg/L that fell with a half-life of 4.4 days. The second patient received a single amiodarone dose of 150 mg intravenously on day 1 postpartum. Breastmilk samples collected on days 4 and 5 postpartum contained amiodarone 0.19 mg/L and 0.17 mg/L, and desethylamiodarone, 0.084 mg/L and 0.085 mg/L, respectively. The authors concluded that breastmilk cessation is probably not necessary after a single dose of 150 mg.

What has been seen in breastfed infants

One mother took amiodarone during the last 5 weeks of pregnancy and until one week after delivery. She was also taking metoprolol throughout pregnancy and at the time of delivery. Possible signs of hypothyroidism occurred transiently in her breastfed infant at 9 and 24 days of age. This was possibly caused by amiodarone or iodine from amiodarone in breastmilk, although residual amiodarone from transplacental passage is also a possible contributing factor; no abnormalities in cornea or the lungs were found.

A pair of twins was born to a woman who received a total of 1487 mg of amiodarone over the first 4 days postpartum. Breastfeeding began 35 days after the end of amiodarone administration when amiodarone and mono-N-desethylamiodarone were still measurable in milk. At that time, the daily intake of breastmilk was 160 mL for the first infant and 120 mL for the second, smaller infant. Breastmilk was mixed with infant formula and accounted for approximately one-quarter of their total daily milk intake. The mother breastfed in infants for approximately two months after starting breastfeeding. At 3 years of age, both infants had a tendency toward obesity, but no other complications or developmental delay.

Effects on milk supply

Relevant published information was not found as of the revision date. However, if amiodarone causes hypothyroidism in the mother, her milk supply could be diminished.