Using Therapeutic Drug Monitoring to Identify Variable Infliximab Metabolism in an Individual Patient With Ulcerative Colitis.

Biological drugs have significantly improved the quality of life of patients with inflammatory bowel disease. However, after 15 years of using these drugs in practice, we just now are beginning to better understand how to use them most effectively. It has become evident that antitumor necrosis factor agents, such as infliximab, have variable drug clearance across individuals, mostly related to the disease burden at the time of an infusion. In this case report, we demonstrate how therapeutic drug monitoring can be used to personalize a dosing regimen to ensure appropriate induction, and to safely deescalate therapy after remission is achieved. By identifying a change in drug clearance in an individual patient over time, we were able to attain significant cost savings despite the high price of serially measured drug and antibody concentrations.