Unable to align the study questions with a complementary trial

The purpose of this study is to develop a predictive model that will allow optimized dosing of infliximab for individual patients

The use of pharmacokinetic analyses incorporating relevant determinants of the infliximab serum concentration can be used to develop a predictive model that will allow optimized dosing for individual patients.

Inclusion Criteria:

• a diagnosis of CD or UC by usual criteria,
• moderate to severely active CD defined by a CDAI ≥ 220, with confirmed endoscopic activity (CDEIS ≥ 6) or moderate to severely active UC, defined by a Mayo Score ≥ 6, with a Mayo endoscopic subscore ≥ 2,
• a need for treatment with IFX for induction of remission as clinically indicated
• patients previously exposed to adalimumab and/or certolizumab who are naïve to infliximab will be allowed to participate.

Exclusion Criteria:

• perianal CD exclusively
• disease limited to the rectum in patients with UC (i.e., disease must extend ≥ 15 cm from the anal verge)
• patients with known antibodies to IFX (ADAs) at baseline
• a contraindication to infliximab therapy
• a contraindication to endoscopy
• an ostomy
• planned surgery
• evidence of severe or unstable hepatic, gastrointestinal, cardiovascular, respiratory, neurological, psychiatric, hematological or renal disease at the discretion of the investigator,
• Pregnancy or breastfeeding,
• treatment with any investigational drug in the past 30 days, or 5 half lives (whichever is longer).

50 patients with Crohn's Disease and 50 patients with Ulcerative Colitis from 10 centres (Canada, United States, Netherlands and Spain).