Asian Journal of Research and Reports in Gastroenterology

Background: Inflammatory bowel disease (IBD) includes two major disorders: ulcerative colitis (UC) and Crohn's disease (CD). Infliximab is a monoclonal antibody that targets tumor                   necrosis factor (TNF) and is used to treat UC and CD. The aim of this study was to evaluate the fecal and blood levels of infliximab and the response to treatment of IBD patients after induction period.

Methods: This was a cross-sectional study conducted at the Imam Khomeini Hospital Complex (January to May 2021). All patients who were candidate for anti-TNF therapy received 5 mg/kg given as an IV induction regimen at 0, 2, and; 6 weeks, followed by a maintenance regimen of 5 mg/kg IV every 8 weeks. At the end of second week (day 14), Patient’s response to treatment with either CDAI or MAYO score, fecal levels of infliximab, serum CRP and albumin level were measured. At the end of 14th week, fecal levels of Infliximab, serum levels of Infliximab serum albumin and CRP level were assessed again.

Results: A total of 28 patients (75% male and 25% female) were included into the study (14 patients with Ulcerative colitis and 14 patients with Crohn's disease). The mean age of the population was 34 ± 10. The distribution of Serum Infliximab after 14 weeks was not the same across clinical response (P < 0.05). Specifically, after adjusting for the Fecal Infliximab concentration day 14, UC patients had higher level of Serum Infliximab level at week 14 (3.853 ± 1.803) compared to the Crohn's disease patients.

Conclusion: Measurement of serum infliximab is widely recommended now and can be used for therapeutic monitoring of patients. The presence of higher serum infliximab is associated with a higher clinical response. In spite of early fecal loss of infliximab, which is an indicator of low serum infliximab level, late fecal infliximab is not a good marker for response since the inflammation is reduced.