Drug Levels and Effects:

Summary of Use during Lactation:

Limited information indicates that maternal doses of imatinib up to 400 mg daily produce low levels in milk. Although one breastfed infant apparently experienced no adverse effects during maternal use of imatinib, no long-term data are available and some authors warn against nursing during imatinib use. Until more data are available, imatinib should be used only with careful monitoring during breastfeeding. Avoiding nursing for 8 to 9 hours after a dose would probably reduce the dosage that the infant receives.

Drug Levels:

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 its active metabolite (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).[1] 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 an its metabolite. Imatinib concentration 15 hours after a dose was 596 mcg/L and CGP 74588 was 1513 mcg/L. 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.[2]

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.[3]

A woman with chronic myeloid leukemia was begun on imatinib 400 mg daily immediately after delivery. She did not breastfeed, but5breastmilk samples were obtained over the 7 days after the first dose, on days 1, 2, 3 and 7 postpartum, apparently 3 hours after the daily doses (exact times not stated). Imatinib milk levels were about half of maternal plasma levels and ranged from 151 to 1153 mcg/L. Milk levels of the metabolite, N-desmethylimatinib were about 3 times those in maternal plasma and ranged from 409 to 1052 mcg/L.[4]

Infant Levels.

Relevant published information was not found as of the revision date.

Effects in Breastfed Infants:

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.[1]

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.[5]

Possible Effects on Lactation:

Relevant published information was not found as of the revision date.


1. Gambacorti-Passerini CB, Tornaghi L, Marangon E et al. Imatinib concentrations in human milk. Blood. 2007;109:1790. PMID:17284536
2. Russell MA, Carpenter MW, Akhtar MS et al. Imatinib mesylate and metabolite concentrations in maternal blood, umbilical cord blood, placenta and breast milk. J Perinatol. 2007;27:241-3. PMID:17377606
3. Ali R, Ozkalemkas F, Kimya Y et al. Imatinib use during pregnancy and breast feeding: a case report and review of the literature. Arch Gynecol Obstet. 2009;280:169-75. PMID:19083009
4. Kronenberger R, Schleyer E, Bornhauser M et al. Imatinib in breast milk. Ann Hematol. 2009;88:1265-6. PMID:19462170
5. Jiang Q, Jiang B, Chen SS et al. [Pregnancy outcome among patients with chronic myelogenous leukemia treated with tyrosine kinase inhibitors]. Zhonghua Xue Ye Xue Za Zhi. 2012;33:6-9. PMID:22575184

Substance Identification:

Substance Name:


CAS Registry Number:


Drug Class:

  • Antineoplastic Agents

  • Protein Kinase Inhibitors

  • Administrative Information:

    LactMed Record Number:


    Last Revision Date:

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