Is 6-MP Safe in Breastfeeding

I am a breastfeeding mother and i want to know if it is safe to use 6-MP? Is 6-MP safe for nursing mother and child? Does 6-MP extracts into breast milk? Does 6-MP has any long term or short term side effects on infants? Can 6-MP influence milk supply or can 6-MP decrease milk supply in lactating mothers?

Antineoplastic and iImmunosuppressive agent. Active metabolite of Azathioprine. Just tiny amounts of this drug have been detected in breast milk ( ). Several breastfed infants whose mothers were treated with it have failed to show side effects.

Most sources consider breastfeeding to be contraindicated during maternal antineoplastic drug therapy, although antimetabolites such as 6-MP appear to pose the least risk to breastfed infants.[1] After high-dose chemotherapy, it might be possible to breastfeed safely during intermittent therapy with an appropriate period of breastfeeding abstinence. Although no data are available to determine an appropriate period to withhold breastfeeding, the drug's terminal half-life suggests that withholding breastfeeding for 1 to 2 days may be sufficient. Chemotherapy may adversely affect the normal microbiome and chemical makeup of breastmilk.[2] In the treatment of conditions such as ulcerative colitis and Crohn's disease, low doses of 6-MP (6-MP) for immunosuppression appear to be acceptable.[3][4][5][6][7][8] No active metabolites of 6-MP were found in the blood of breastfed infants whose mothers were taking azathioprine and no adverse effects attributable to 6-MP or azathioprine have been noted. See the Azathioprine record for details. Mothers with decreased activity of the enzyme that detoxifies 6-MP metabolites may transmit higher levels of drug to their infants in breastmilk. It might be desirable to monitor exclusively breastfed infants with a complete blood count with differential, and liver function tests if 6-MP is used during lactation, although some authors feel that monitoring is unnecessary.[9] Avoiding breastfeeding for 4 hours after a dose should markedly decrease the dose received by the infant in breastmilk.[10]

In The Netherlands, 30 infants of mothers taking either azathioprine (n = 28) or 6-MP (n = 2) for inflammatory bowel disease during pregnancy and postpartum were followed at 1 to 6 years of age using a 43-item quality of life questionnaire. Of this cohort, 9 infants were breastfed for a mean of 7 months (range 3 to 13 months) No statistically significant differences were found between breastfed and formula-fed infants in any of the 12 domains of the survey.[14] A prospective cohort study followed pregnant women with inflammatory bowel disease throughout pregnancy and for 12 months postpartum. Women were assigned to one of the following groups: unexposed (no thiopurines or anti-TNF agents); group A (azathioprine or 6-MP); group B (infliximab, adalimumab or certolizumab pegol) and group AB (both a thiopurine and an anti-TNF agent). Of 1052 women enrolled in the study, 72% breastfed their infants, although the extent and duration were not stated in the abstract. A total of 264 women were exposed to a thiopurine and 59 were exposed to a thiopurine plus an anti-TNF agent. The use of a thiopurine alone was not associated with any complication in the infants and their growth and development were normal throughout the 12 months. Infants exposed to both a thiopurine and an anti-TNF agent had a 50% increase in the number of infections between 9 and 12 months of age. The relationship of this increase with breastfeeding could not be determined from the available data.[15] A national survey of gastroenterologists in Australia identified 21 infants who were breastfed by mothers taking a combination of allopurinol and a thiopurine (e.g. azathioprine, 6-MP) to treat inflammatory bowel disease. All had taked the combination during pregnancy also. Two postpartum infant deaths occurred, both at 3 months of age. One was a twin (premature birth-related) and the other from SIDS. The authors did not believe the deaths were medication related.[16] No information was provided on the extent of breastfeeding, drug dosages or the outcomes of the other infants.