Is Imatinib safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Imatinib. This is a summary of that source — not our own verdict.
Effects on the breastfed infant
A woman receiving oral imatinib 400 mg daily for chronic myeloid leukemia breastfed her infant. No adverse effects were noted in the infant during the first 2 months of nursing.[ 4 ] One woman with chronic myelogenous leukemia received imatinib 400 mg daily throughout pregnancy and during breastfeeding (extent not stated) for nearly 6 months postpartum. Her infant reportedly grew and developed normally.[ 11 ] A woman with chronic myeloid leukemia received imatinib 400 mg daily starting at week 8 of pregnancy and continuing throughout 8 months of breastfeeding (extent not stated). The infant was healthy, but an atrial septal defect was repaired at 30 months of age. It was thought to be unrelated to imatinib therapy.[ 12 ] A pregnant woman with Philadelphia chromosome-positive chronic myelogenous leukemia was started on imatinib 400 mg daily during pregnancy. After delivery, her preterm infant was fed colostrum until the middle of the fifth day postpartum when exclusive formula feeding was instituted. The infant was treated for apnea of prematurity and discharged on day 25 of life. No adverse effects on growth or development were noted during the first year of life.[ 10 ]
Effects on milk supply
Relevant published information was not found as of the revision date.
Levels in milk
Imatinib is metabolized to an equally active metabolite, CGP 74588. The half-lives of the drug and its active metabolite are 18 and 40 hours, respectively, so accumulation might occur in the infant. Maternal Levels. A woman receiving oral imatinib 400 mg daily for chronic myeloid leukemia breastfed her infant. During week 4 postpartum, serum and milk levels of imatinib and CGP 74588 were measured before and at several times during the 9 hours after the dose. The highest concentrations of imatinib and its metabolite were at 2 and 4 hours after the dose. Peak concentrations of imatinib ranged between 1.1 and 1.4 mg/L and were 0.8 mg/L for the metabolite. The concentrations of both were 25 to 50% lower 9 hours after the dose. Milk and serum levels were also measured during the second month of breastfeeding with similar results (details not reported).[ 4 ] Using these data, the estimated maximum dosage of the drug and metabolite that a fully breastfed infant would receive is 0.3 mg/kg daily or 4.5% of the maternal weight-adjusted dosage. A woman who was 7 days postpartum and had been taking imatinib 400 mg daily since the middle of her pregnancy had a single milk sample analyzed for the drug and its metabolite. Milk concentration 15 hours after a dose was 596 mcg/L for imatinib and 1513 mcg/L for the metabolite. The authors estimated that a fully breastfed infant would receive between 1.2 and 2 mg of the drug and metabolite daily with this maternal dose.[ 5 ] A woman who took imatinib 400 mg daily during pregnancy and postpartum delivered a normal infant, but did not breastfeed. Breastmilk imatinib concentrations were measured on the 7th, 14th, 15th and 16th days postpartum at times ranging from 10 to 16 hours after the previous dose. Breastmilk concentrations ranged between 1.4 and 2.6 mg/L.[ 6 ] A woman with chronic myeloid leukemia was begun on imatinib 400 mg daily immediately after delivery. She did not breastfeed, but 5 breastmilk samples were obtained over the 7
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.