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Aims: Information on breastfeeding and safety of biologics in infants is lacking due to difficulties in case collection. We evaluated methods for determining the concentration of biologics in breast milk using a dry filter method that can simplify the collection, storage and transport of breast milk. Methods: To generate dried filter paper (DFP) samples, approximately 30 μL of breast milk was placed onto a Whatman 903 card and punched out. After extraction, the supernatant was measured using an enzyme‐linked immunosorbent assay. Three concentrations of each drug were prepared in liquid breast milk (LBM) and DFP samples to determine their stability up to 28 days after storage at 2–8°C or −20°C for LBM and 25 ± 5°C for DFP. LBM and DFP samples were also provided by nursing mothers using biologics during lactation, and drug concentrations in both samples were compared. The agreement between the two measurement methods was confirmed by Bland–Altman analysis. Results: Breast milk was provided by 12 mothers who used biologics (tocilizumab, abatacept, etanercept, golimumab, sarilumab and belimumab). The coefficients of variation for within‐run and between‐run precision for the six drugs were within 15% for both LBM and DFP, and accuracy was within 90%–110% of the quality controls. After 28 days, concentrations remained at more than 90%. The difference between the values obtained by each method was within the acceptable range of error (−12.1 to +16.6 ng/mL). Conclusions: A method for determining the concentration of biologics using DFP is expected to help improve pharmacotherapy for lactating women. [ABSTRACT FROM AUTHOR]

The demand for tocilizumab is increasing in women who wish to bear children and who have active rheumatoid arthritis. Described here is a woman with rheumatoid arthritis who discontinued her tocilizumab therapy at the end of the first trimester and resumed it after delivery and where tocilizumab levels in maternal serum, infant serum, and the breast milk were measured. Tocilizumab was not detected in maternal serum just before delivery, or in umbilical cord blood or infant serum after birth. Tocilizumab levels in colostrum after intravenous injection were 0.57% of those in serum. Tocilizumab treatment in the first trimester was not associated with a significant drug level in the fetus at delivery and no fetal complications were noted. [ABSTRACT FROM AUTHOR]

The article discusses a study that measured abatacept concentrations in the breast milk of a 41-year-old nursing mother with rheumatoid arthritis and examined the safety of her breastfed infant. Highlights include the approval of the study by the ethics committee of the National Center for Child Health and Development, her treatment with tocilizumab and certolizumab pegol before switching to abatacept treatment, and the infant Apgar scores at one and five minutes.