Optimizing thiopurine therapy in inflammatory bowel disease.

Despite recent advances, the therapeutic armamentarium for inflammatory bowel disease (IBD) is still limited. In addition, a step-up approach is recommended for most IBD patients. Thus, optimizing each medical therapy before switching to another drug class is the rule in clinical practice. Conventional therapies for IBD have not received the same amount of attention as biologic therapies over the last decade. However, due to their efficacy, safety, and low cost the thiopurine drugs azathioprine and 6-mercaptopurine remain the backbone of therapy for IBD. Pharmacogenomic advances and increased knowledge of their metabolism are allowing dosage optimization. Herein, after describing the pharmacogenetics and pharmacokinetics of thiopurines, we will discuss how to optimize thiopurine therapy. We will then underscore the need to take into account safety issues when optimizing thiopurine treatment.