Abstract
Interleukin-23 (IL-23) inhibitors have rapidly become an essential component of the therapeutic armamentarium for inflammatory bowel disease (IBD). Risankizumab, mirikizumab, and guselkumab share broadly similar pharmacokinetic and pharmacodynamic properties, including linear clearance, long half-lives, and low immunogenicity. While therapeutic drug monitoring (TDM) is well established in the use of anti-TNF agents, its role in IL-23 inhibitors remains undefined. Emerging evidence, mostly for risankizumab, demonstrates dose-response relationships, suggests potential maintenance thresholds, and outlines possible dose optimization strategies. However, this preliminary data is predominantly retrospective, often single-center, and involves a small number of patients. Until more robust evidence supporting the efficacy of TDM and dose optimization emerges, routine use of this clinical practice in IBD remains investigational.