Use of Two Biologics During Pregnancy: Infliximab and Vedolizumab: A Case Study.

BACKGROUND: Pregnancy is associated with altered pharmacokinetics for several drugs.The blood concentration of infliximab increases during pregnancy, whereas that of vedolizumab tends to decrease. As autoimmune disease activity during pregnancy can lead to adverse pregnancy outcomes, monitoring drug concentrations during pregnancy is important. METHODS: This study reports a 32-year-old female patient with severe juvenile idiopathic arthritis and Crohn disease who was treated with dual biologic therapy throughout her pregnancy. The measurements were performed as part of routine care. RESULTS: The patient was treated with vedolizumab and infliximab during the course of her pregnancy. Both autoimmune diseases remained unaffected throughout pregnancy, and therapeutic drug concentrations were monitored to guide treatment. The patient had gestational diabetes and mild polyhydramnios. Ultimately, the pregnancy was complicated by preterm delivery at 33 weeks and 5 days of gestation, with a good birth weight of 2425 g at p85 without growth retardation. CONCLUSIONS: Therapeutic drug monitoring (TDM) supports optimal dosing and effective disease control, highlighting the importance of individual interpretations. All TDM-initiated dosing changes were based on expert opinions, owing to the lack of validated guidelines on dosing during pregnancy. However, preterm birth could not be avoided and may be influenced by underlying autoimmune diseases, gestational diabetes, and mild polyhydramnios. Multidisciplinary care is essential in pregnant women with autoimmune disorders. Prospective research focusing on drug concentrations, disease activity, and the risk of adverse pregnancy outcomes is needed to understand the safety and implications of dual biologic therapies during pregnancy.