Tofacitinib concentrations in plasma and breastmilk of a lactating woman with ulcerative colitis.

JAK inhibitors are used to treat immune-mediated diseases among people of childbearing age. The US Food and Drug Administration, European Medicines Agency, American Gastroenterological Association, and European Crohn's and Colitis Organization recommend avoiding breastfeeding while on JAK inhibitors, including tofacitinib, because there are no human data. 1 Torres J Chaparro M Julsgaard M et al. European Crohn's and Colitis guidelines on sexuality, fertility, pregnancy, and lactation. J Crohn's Colitis. 2023; 17: 1-27 Crossref PubMed Scopus (19) Google Scholar , 2 Mahadevan U Robinson C Bernasko N et al. Inflammatory bowel disease in pregnancy clinical care pathway: a report from the American Gastroenterological Association IBD Parenthood Project Working Group. Gastroenterology. 2019; 156: 1508-1524 Summary Full Text Full Text PDF PubMed Scopus (177) Google Scholar The concentration of tofacitinib in milk from lactating rats was two times higher than maternal blood concentrations at all measured timepoints. 3 PfizerPrescribing Information, section 8.2: lactation. https://labeling.pfizer.com/showlabeling.aspx?id=959Date: 2020 Date accessed: May 12, 2023 Google Scholar Therefore, Pfizer (New York, NY, USA), the manufacturer, recommends that breastfeeding in humans should be avoided for at least 18 h after the last dose. 3 PfizerPrescribing Information, section 8.2: lactation. https://labeling.pfizer.com/showlabeling.aspx?id=959Date: 2020 Date accessed: May 12, 2023 Google Scholar In this Correspondence, we report the first human concentrations of tofacitinib in breastmilk.