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Azathioprine and breastfeeding

I frequently get asked about the compatibility of azathioprine during breastfeeding . It is used for several auto-immune diseases including inflammatory bowel disease and sometimes rheumatoid arthritis. It is actually quite widely taken by breastfeeding mothers from the questions I receive.

This information is taken from Breastfeeding and Medication

“Azathioprine is an immunosuppressive anti-metabolite. It is converted to mercaptopurine in the body. It has a corticosteroid-sparing effect and is widely used to produce and maintain remission in IBD, as well as conditions such as lupus and rheumatoid arthritis.

Traditionally, breastfeeding by mothers have been discouraged from continuing to breastfeed if taking azathioprine because of the theoretical risks of infant bone marrow suppression, susceptibility to infection, growth retardation and pancreatitis.

According to recent research (Gardiner et al. 2007) breastfeeding need not be withheld in infants whose mothers are taking azathioprine. Gardiner et al. studied four mothers taking azathioprine. The metabolites 6-MP and 6-TGN were undetectable in neonatal blood and no clinical signs of immunosuppression were observed in the infants. Similarly Moretti et al. (2006) studied four babies and measured levels of 6-MP in breastmilk and neonatal blood for drug levels, white cell and platelet counts. Levels of metabolites were below the level of detection in the neonates and no clinical signs of immunosuppression were observed. Sau et al. (2007) studied ten women and similarly found no immunosuppression. Women taking azathioprine should therefore not be discouraged from breastfeeding.

It is licensed to be given to children over the age of 2 years at a dose of 2 mg per day initially for severe UC and CD. Relative infant dose is quoted as 0.07% to 0.3% (Hale 2017 online access).

The BNF states that it is present in milk in low concentrations, that there is no evidence of harm in small studies and the drug may be considered if the potential benefit outweighs the risk.

Compatible with breastfeeding according to more recent studies; metabolites undetectable in infant’s blood and no signs of immunosupression in studies.

  • Gardiner SK, Gearry RB, Roberts RL, Zhang M, Barclay ML, Begg EJ, Exposure to thiopurine drugs through breastmilk is low based on metabolite concentrations in mother-infant pairs, Br J Obstet Gynecol, 2007;114:498–501.
  • Sau A, Clarke S, Bass J, Kaiser A, Marinaki A, Nelson-Piercy C, Azathioprine and breastfeeding – is it safe?, BJOG, 2007;114:498–501.
  • Moretti ME, Verjee Z, Ito S, Koren G, Breastfeeding during maternal use of azathioprine, Ann Pharmacother, 2006;40:2269–72.
  • Hale TW Medications and Mother’s Milk”

Any queries please contact me on wendy@ breastfeeding-and-medication.co.uk

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