Pharmacokinetics of biologics and the role of therapeutic monitoring.

Biologic therapies, including the anti-tumor necrosis factor-α and cell adhesion molecule inhibitor drugs, have revolutionized the treatment of moderate-to-severe inflammatory bowel disease. Since the introduction of anti-tumor necrosis factor therapies, the strategy of empiric dose-escalation, either increasing the dose or frequency of administration, has been used to recapture clinical response in inflammatory bowel disease. Disparate clinical outcomes have been linked to serum drug and antidrug antibody levels. Therapeutic drug monitoring has emerged as a framework for understanding and responding to the variability in clinical response and remission.