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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]

Aims: Tocilizumab (TCZ), a humanized anti‐interleukin‐6 receptor monoclonal antibody, is used to treat rheumatic diseases. There is limited information about the administration of TCZ during lactation. The dried spot method, a simple technique for processing biological samples which involves placement of a drop of specimen onto filter paper, has been used in clinical pharmacology to determine various drug concentrations. This study examined the feasibility of sample collection using the dried milk spot (DMS) method for obtaining data about the transfer of TCZ into breast milk. Methods: Concentrations of TCZ determined using DMSs prepared by patients were compared with those using liquid breast milk. Results: In an enzyme‐linked immunosorbent assay of TCZ in DMSs, the accuracy ranged from 93.0% to 113.8% and the precision ranged from 0.3% to 8.4%. All concentrations of TCZ were within 15% of the reference value when analyzed on separate days. TCZ in DMSs at room temperature, 4°C, and −20°C were stable for 28 days. Extracted TCZ concentrations from patient‐prepared DMSs were strongly correlated with those of liquid samples (r = 0.996). In a pharmacokinetic study, the median (range) maximum and minimum concentrations were 113 ng/mL (68‐205) and 8.5 ng/mL (4.8‐13.4), respectively. The milk‐to‐serum ratio at the trough TCZ concentration of 3 lactating mothers were 0.0015, 0.00082 and 0.0014. Conclusions: The DMS method for measuring TCZ transfer into breast milk may be reliable and feasible, and should contribute to evaluating the safety of breast‐fed infants whose mothers receive TCZ during lactation. [ABSTRACT FROM AUTHOR]

The infant dose I via i breast milk was 0.95% of the maternal daily dose, that was considered to be acceptable,8 even though the drug information states that etizolam use should be avoided during breastfeeding.5 To clarify more accurate information about etizolam excretion into breastmilk, a detailed etizolam concentration profile including maximum concentration in breastmilk following oral etizolam administration will be required. Anxiety disorders may require pharmacological treatment, and it has been estimated that 10% to 26% of pregnant women with these disorders are prescribed benzodiazepines or benzodiazepine-like hypnotic drugs.1,2 These medications cross the placental and blood-brain barriers, may affect fetal growth and development,3 and have been associated with increased risks of preterm birth, low Apgar score, neonatal intensive care unit admission, and neonatal respiratory distress syndrome.4 Etizolam, a benzodiazepine-class anxiolytic, is prescribed for the treatment and management of agitation, tension, insomnia and anxiety.5 Due to the limited market distribution and use of etizolam worldwide, only one report from Japan published the information on etizolam transfer into breast milk.6 Furthermore, the information on etizolam transfer into the fetal circulation is limited. Benzodiazepine concentrations in the breast milk and plasma of nursing mothers: Estimation of relative infant dose. [Extracted from the article]