Therapeutic Drug Monitoring in Inflammatory Bowel Disease

Abstract Inflammatory bowel disease (IBD) is a problem that directly affects the quality of life of patients suffering from this condition. Monitoring the serum level of infliximab (IFX) (TDM) is an important tool for guiding therapeutic decisions in IBD patients. The purpose of this study was to determine the significance of quantitatively measuring the serum level of IFX (TDM) and antibody to IFX (ATI). Methods and materials: Prospective observational study involving 40 IBD patients on IFX therapy, including 14 Proactive (week 06 of the induction phase) and 26 Reactive (maintenance phase). Immediately prior to the infusion, blood samples were drawn and measured using a Bulhlmann rapid test instrument. Serum concentrations of IFX were categorized as supratherapeutic (>7.0 micrograms/ml), therapeutic (between 3.0 and 7.0 micrograms/ml), and subtherapeutic (3.0 micrograms/ml). When the serum concentration of IFX was 3 mcg/ml (subtherapeutic), the ATI was measured. 25 patients with CD and 15 patients with UC were evaluated. Only three of the twenty patients with subtherapeutic serum levels had a positive ATI, and both were reactive; two had CD and one had UC. There was a statistically significant difference between reactive and proactive patients with respect to levels of CRP (p = 0.042), with proactive DNS patients suffering greater alterations in CRP and albumin.