Transplacental transfer of immunosuppressants and biologics used for the treatment of inflammatory bowel disease.

The aim of the present article was to review the role of the placenta function in the transfer of immunosuppressants and monoclonal antibodies used for the treatment of inflammatory bowel disease, as well as the available data regarding the safety of these therapies during pregnancy. Methotrexate can cause congenital abnormalities and is contraindicated during pregnancy. Available data suggest that thiopurines are safe and well tolerated during pregnancy. Treatment with cyclosporine for steroid refractory ulcerative colitis during pregnancy can be considered effective and safe. Biological therapies appear to be safe during pregnancy, as no increased risk of malformations has been demonstrated. Transplacental exchanges are known to involve passive transfer, active transport and facilitated diffusion. Thiopurines are transported by passive transfer. The transport across the placenta of corticosteroids, methotrexate and cyclosporine is modulated by protein "pumps". Infliximab and adalimumab bind the FcRn-receptor as other IgG proteins do. The mechanisms of the diffusion of certolizumab across the placenta barrier remain unknown.