Biologic therapy in Crohn's disease.

Crohn's disease is a complex disease process causing transmural inflammation of the gastrointestinal tract, which produces a constellation of symptoms including abdominal pain, frequent loose stools, fistula formation, and extraintestinal manifestations. Biologic therapy, including tumor necrosis factor alpha inhibitors, are a growing class of agents, which have demonstrated efficacy in the treatment of moderate to severe Crohn's disease. Their indications for use have grown, as has the understanding of their associated safety concerns.