Is Elexacaftor, Tezacaftor and Ivacaftor safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Elexacaftor, Tezacaftor and Ivacaftor. This is a summary of that source — not our own verdict.
Effects on the breastfed infant
A survey was sent to lead clinicians of adult CF centers in Europe, the United Kingdom, United States of America, Australia and Israel requesting anonymized data on pregnancy outcomes in women using CFTR modulators during pregnancy and lactation. Responses were received from 31 centers and one woman with CF for a total of 64 pregnancies in 61 women resulting in 60 live births. Thirteen infants were breastfed on ivacaftor alone, 9 infants were breastfed on lumacaftor and ivacaftor, and 5 infants were breastfed on tezacaftor and ivacaftor for a total of 27 infants exposed to ivacaftor in breastmilk, all with no reported complications. The extent of breastfeeding was not reported.[ 11 ] An updated survey by the same authors asked CF clinicians to report on pregnant women exposed to the elexacaftor, tezacaftor and ivacaftor combination during pregnancy and breastfeeding. Twenty-six infants were breastfed (extent not stated) during maternal use of the combination. No adverse effects were reported in the breastfed infants.[ 12 ] An infant was born to a mother taking elexacaftor, ivacaftor and tezacaftor for cystic fibrosis. The infant was breastfed (extent not stated). Although the infant had cystic fibrosis-causing CFTR mutations, the infant was healthy and tested negative for cystic fibrosis on newborn screening. The authors expressed concern that the drugs received transplacentally and in breastmilk caused a false negative screening test.[ 13 ] A mother who was a heterozygous carrier of the F508del gene became pregnant with a homozygous infant. At 32 weeks of pregnancy, the mother began elexacaftor, ivacaftor and tezacaftor in the usual adult dosage to treat her fetus who had evidence of meconium ileus. The infant was born at 36 weeks and given pancreatic enzyme replacement therapy with breastfeeding while maternal treatment continued. The infant s fecal elastase, transaminases and bilirubin were normal at about 1 month of age. The infant s sweat chloride, although low
Effects on milk supply
A retrospective review was performed on prospectively collected data at a cystic fibrosis center in England of women with cystic fibrosis who delivered between 2010 and 2023. Twenty-four women who were taking elexacaftor, tezacaftor and ivacaftor (ETI) were compared to 26 women with cystic fibrosis who were not taking the combination. Fifty percent of babies in the ETI group were breastfed compared to 35% in non-ETI group. The difference was statistically significant.[ 21 ]
Levels in milk
Maternal Levels. Two nursing mothers with cystic fibrosis who were taking elexacaftor, ivacaftor and tezacaftor, had their milk samples analyzed 2 or 3 times between 15 and 60 days postpartum. Milk levels were all 1 micromolar in one woman at 15 and 60 days postpartum. The other woman had milk levels of the 3 drugs 1 micromolar at 30 days postpartum, milk ivacaftor and tezacaftor levels of 1 micromolar and elexacaftor level of about 1 micromolar at 45 days postpartum. Milk levels of all drugs tended to increase slightly over time.[ 3 ] Two nursing mothers with cystic fibrosis were taking elexacaftor, ivacaftor and tezacaftor in unspecified dosages. The concentrations in milk at unreported times after a dose were ivacaftor 0.03 micromolar (11.8 mcg/L) and 0.26 micromolar (102 mcg/L); tezacaftor levels were 0.12 micromolar (62.5 mcg/L) and 0.39 micromolar (203 mcg/L); and elexacaftor levels were 0.74 micromolar (442 mcg/L) and 1.29 micromolar (771 mcg/L).[ 4 ] A woman with cystic fibrosis received elexacaftor 100 mg, tezacaftor, 50 mg, ivacaftor 75 mg and additional ivacaftor 150 mg daily while exclusively breastfeeding her 3-month-old infant. Fasting breastmilk samples were collected 12 hours after the last dose of ivacaftor 150 mg and before the morning dose of elexacaftor, tezacaftor, and ivacaftor. Concentrations in milk were elexacaftor 1049 mcg/L, tezacaftor 761 mcg/L and ivacaftor 1795 mcg/L.[ 5 ] A woman who was a cystic fibrosis carrier took ETI postpartum to treat her infant with cystic fibrosis. After 9 days of therapy, milk levels were: elexacaftor 25 mcg/L, tezacaftor 30 mcg/L and ivacaftor 25 mcg/L. The sample and dosage times were not reported. The authors speculated that the low milk levels might have been related to the mother s weight (170 kg; BMI 34.5), because her blood levels were low, but within the usual range.[ 6 ] A woman who was a CF carrier began ETI at 24 weeks and 4 days gestation to protect her fetus and newborn who was diagnosed with CF
Source: NIH LactMed (National Library of Medicine).
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.