Clinical pharmacology in inflammatory bowel disease: Optimizing current medical therapy

Effective therapy of inflammatory bowel disease (IBD) often requires the implementation of diverse pharmacologic strategies (Fig. 1). Unlike, for example, the treatment of an acid-peptic disease where blockade of the proton pump, a specific target enzyme, is highly effective in inhibiting the pathogenic process, investigators have been unable to identify a specific unifying etiologic or pathogenic factor in IBD to pharmacologically target. For this reason, current therapy of ulcerative colitis (UC), Crohn's disease (CD) and pouchitis often requires the use of more than one drug that belong to different therapeutic classes, and that are non-specific in action. In this chapter the clinical pharmacology of drugs that are effective in IBD is reviewed. The pharmacokinetics and mechanisms of action of these agents are discussed, with particular reference to their use in IBD patients. Although the list of medicines available to treat IBD is expanding, none is universally effective or safe. Therefore, we also explore various strategies to individualize and optimize drug therapy in IBD, including therapeutic drug monitoring and the potential use of pharmacogenetic data to guide therapeutic decision-making. Several agents recently introduced for use in IBD, such as mycophenolate mofetil, interleukin (IL)-10 and thalidomide are not discussed because of a paucity of information on their use. (Figure presented).