Omalizumab concentrations in pregnancy and lactation: A case study

If increasing doses of antihistamines or agents with other mechanisms are required, omalizumab is considered.2 According to a registry-based prospective cohort study of pregnancy exposure, more than 99% of pregnancies led to live births in both the exposure (n = 250, 246 patients with first-trimester exposure) and control groups (n = 1153), and the rate of major congenital anomalies in registry infants was similar to that in infants in the comparator cohort (approximately 8.0% in both groups).3 Regarding omalizumab secretion into breast milk, because omalizumab is a large protein molecule, the amount in milk is likely to be very low. Omalizumab concentrations were measured in the maternal blood in the third trimester of pregnancy and in the cord blood immediately after delivery (Figure 1). Because the calibration range for omalizumab quantification was 0.5 to 200.0 ng/mL, samples were diluted 1 to 10,000 times and fell within the range of the standard curve. The infant was exclusively breastfed, at a frequency of 6-12 times per day until at least 4 months after birth. Because omalizumab concentrations in breast milk were low compared with those in maternal serum (Figure 1), omalizumab exposure due to breastfeeding is likely also low.