Background and Importance Anti-TNF drugs are often considered the primary treatment for most patients with inflammatory bowel disease. However, there is a significant interindividual variability in the therapeutic response. Approximately 30% of patients do not respond to induction (primary failure) and more than 50% of patients lose response over time (secondary failure). Given that there is a strong correlation between anti-TNF drug levels and its efficacy, pharmacokinetic monitoring of plasma levels has become a useful strategy to optimise the treatments.

Aim and Objectives To analyse the percentage of pharmacokinetic recommendations accepted by the physician to optimise anti-TNF treatment in patients with inflammatory bowel disease

Material and Methods Prospective, observational study, which included patients with inflammatory bowel disease treated with adalimumab and infliximab from february to october 23. Demographic variables (age, sex), diagnosis (Crohn’s disease or ulcerative colitis), treatment (adalimumab or infliximab) and type of recommendation (dose intensification, interval intensification or both, regimen maintenance, treatment change, treatment de-intensification or suspension) were collected. The measurement of drug levels was conducted using a rapid determination system (RIDA®Quick System) followed by interpretation using a computer application based on analysis by Bayesian methods. (PKS® Abbott). The data analysis was based on pharmacokinetic models published in the literature.^1,2 Subsequently, the pharmacokinetic recommendation was provided to the physician, who made the final decision.

Results Twenty-eight patients (50% men and 50% women) with a mean age of 40 years were included. Regarding diagnosis, 53,6% was ulcerative colitis and 46,4% was Crohn’s disease. Thirty-three determinations were made (17 adalimumab and 13 infliximab). The total percentage of acceptance of the pharmacokinetic recommendations was 84,8% and was distributed as follows: Maintenance of regimen (33.3%), interval intensification (27.7%), dose intensification (12.12%), dose and interval intensification (12.12%), change of treatment (9.09%), de-intensification (3.03%) and discontinuation of treatment (3.03%).

Conclusion and Relevance The degree of acceptance of the pharmacokinetic recommendations was high. It remains to be determined in the long term whether this type of intervention will yield a positive clinical impact, potentially enhancing treatment persistence.

References and/or Acknowledgements 1. Adedigbo A Fasanmade, Omoniyi J Adedokun, et al. Eur J Clin Pharmacol (2009) 65:1211–1228.

2. Niels Vande Casteele, Filip Baert, et al. Journal of Crohn’s and Colitis. 2019, 1248–1256.

Conflict of Interest No conflict of interest.