Advances in the Diagnosis and Management of Inflammatory Bowel Disease: Biologics, Small Molecules, and Beyond

This chapter examines the rapidly expanding therapeutic landscape of Crohn’s disease and ulcerative colitis, with a focus on the mechanisms of action, clinical efficacy, and comparative effectiveness of approved biologic agents — including anti-TNF, anti-integrin, and anti-IL-12/23 therapies — alongside emerging small-molecule inhibitors such as Janus kinase inhibitors and sphingosine-1-phosphate receptor modulators. It also addresses evolving treat-to-target strategies, therapeutic drug monitoring, optimisation of combination therapy, and the challenges of managing refractory and complex disease phenotypes.