Tocilizumab drug levels during pregnancy and lactation: A woman who discontinued tocilizumab therapy until the end of the first trimester and resumed it after birth

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 .