Azathioprine and breastfeeding—is it safe?

Abstract

Traditionally, women receiving azathioprine have been discouraged from breastfeeding because of theoretical potential risks of neonatal bone marrow suppression, susceptibility to infection, and pancreatitis. The aims of this study were to measure the concentration of 6-mercaptopurine (6-MP) in breast milk of mothers receiving azathioprine and in the blood of their babies and to investigate any immunosuppressive effects on the babies. Women receiving azathioprine, who after appropriate counselling wished to breastfeed their babies, were approached for inclusion in the study. Breast milk samples were obtained from recruited women, and 6-MP levels were measured in each breast milk sample. Haemoglobin level, white cell and platelet counts, and 6-MP and 6-thioguanine nucleotides (6-TGN) levels were measured in the respective neonatal blood samples. Clinical signs of immunosuppression in the neonates were noted. Thirty-one breast milk samples were collected from ten women. Low concentrations of 6-MP (1.2 and 7.6 nanograms/ml, compared with therapeutic immunosuppressant level of 50 nanograms/ml in serum) were detected in two breast milk samples obtained from one woman. 6-MP was not detected in any of the other 29 samples. 6-MP and 6-TGN were undetectable in the neonatal blood. There were no clinical or haematological signs of immunosuppression in any of the ten neonates. We conclude that breastfeeding should not be withheld in infants of mothers receiving azathioprine.

Pregnancy and Breastfeeding in Patients with Crohn’s Disease

“…Expert opinion differs regarding the use of azathioprine and 6-MP during lactation, but recent data support the view that these drugs may be prescribed on an individual basis and with caution during breastfeeding, as they are transmitted at very low levels in breast milk [74,75,76,77]. 6-Thioguanine concentration measurement offers a valuable means of objectively assessing infant exposure.…”

Review article: a decision‐making algorithm for the management of pregnancy in the inflammatory bowel disease patient

“…The concentration of MP was 1.2 and 7.6 ng/mL, compared with the therapeutic immunosuppressant level of 50 ng/ mL in serum. 115 In a study of 11 mothers taking AZA during pregnancy and lactation compared with 12 patients without any immunosuppressive therapy, there was no increased risk of infections in babies exposed to AZA in utero and via breastfeeding. 116 The ECCO consensus supports that breastfeeding under maintenance AZA therapy could be advised for women who wish to nurse their infants.…”

“…The risks and benefits of continuing treatment with thiopurines should be discussed with the mother 114,117 and the infants should receive continued monitoring and long-term assessment. 115,118 Corticosteroids. Corticosteroids are secreted into breast milk, and foetal levels are 10-12% of the maternal levels, depending on the steroid preparation.…”

Management of inflammatory bowel disease in pregnancy

“…Several small studies have shown very low levels of drug excretion in breast milk that do not amount to clinically significant concentrations in the healthy breastfeeding infant [88][89][90]. Caution should be used in infants with compromised immune systems.…”