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.