Monoclonal antibody against immunoglobulin E (IgE).It is an immunoglobulin G (IgG) of huge molecular weight that binds with great affinity to IgE, blocking it, forming IgG-IgE complexes of even larger size and molecular weight. Since the last update, we have not found published data on its excretion in breast milk. Its high molecular weight makes its excretion in milk very unlikely. Its low oral bioavailability would hinder its transfer to infant plasma from ingested breast milk since, due to its protein nature, it degrades in the gastrointestinal tract, and is not absorbed, except in premature infants and the immediate neonatal period, when there may be greater intestinal permeability. It is known that in non-human primates (cynomolgus monkeys) it is excreted in very small amounts: levels of omalizumab in milk were 0.15% (EMA 2016) or 1.5% (Grunewald 2015, FDA 2007) with respect to maternal serum concentration. Its use is authorized in children from 6 years of age (EMA 2016, Pediamecum 2015). Other monoclonal antibodies of similar structure and molecular weight (adalimumab, certolizumab, infliximab) are known not to be excreted in breast milk in clinically significant amounts and do not harm the infant, and are therefore considered compatible with breastfeeding. See below the information of these related products: