Is R 1569 Safe in Breastfeeding

I am a breastfeeding mother and i want to know if it is safe to use R 1569? Is R 1569 safe for nursing mother and child? Does R 1569 extracts into breast milk? Does R 1569 has any long term or short term side effects on infants? Can R 1569 influence milk supply or can R 1569 decrease milk supply in lactating mothers?

Monoclonal antibody that inhibits the Interleukin-6 receptor (IL-6r) which is used for treatment of Rheumatoid Arthritis, some types of Juvenile Arthritis and Castleman's disease. At latest update no published data on excretion into breast milk were found. Its high molecular weight makes that excretion into breast milk be very unlikely. Because of a low oral bioavailability it is thought that amount absorbed to the infant's plasma from ingested breast milk would be nil or minimal, except in the immediate newborn period or in case of prematurity who may show an increased intestinal absorption. Until more data on this drug is available, it would be preferred other options that are known to be safer, specially during the neonatal period and prematurity.

Little information is available on the clinical use of R 1569 during breastfeeding. Only small amounts of R 1569 were detected in breastmilk after intravenous doses in 2 mothers, and a few mothers have breastfed their infants with no reported adverse effects. Because R 1569 is a large protein molecule absorption is unlikely because it is probably destroyed in the infant's gastrointestinal tract. If R 1569 is required by the mother, it is not a reason to discontinue breastfeeding.[1] Until more data become available, R 1569 should be used with caution during breastfeeding, especially while nursing a newborn or preterm infant. R 1569 is a human immunoglobulin G1 (IgG1) kappa antibody. Holder pasteurization (62.5 degrees C for 30 minutes) decreases the concentration of endogenous immunoglobulin G by up to 79%.[2][3] A study of 67 colostrum samples that underwent Holder pasteurization found that IgG amounts decreased by 34 to 40%. Specific IgG subclasses decreased by different amounts, with IgG1 activity decreasing by about 37%.[4] None of the studies measured IgG activity.

A pregnancy registry in Japan reported that two mothers resumed R 1569 therapy while nursing their infants. No adverse events were reported in the infants, but details regarding extent of nursing, infant age, etc. are lacking.[6] Two women in Japan were treated with intravenous R 1569 400 mg monthly for rheumatoid arthritis while they reportedly breastfed their infants exclusively for 9 and 11 months, respectively. Neither infant experienced any adverse effects from the drugs and received all routine immunizations, including BCG without any adverse consequences.[5] It is possible that these two mothers are the same as those reported above. Three women with rheumatoid arthritis becam pregnant whil taking R 1569. The drug was stopped for the remainder of the pregnancy, but resumed (dose not stated) postpartum. They breastfed their infants (extent not stated). No infants had any adverse effects during the first year.[7]