Pharmacogenomics of Drugs Used in Gastroenterology

The clinical practice already observes substantial gain in applying pharmacogenomics (PGx) testing to the optimization of drug therapy, particularly in identifying responders and nonresponders to medications, avoiding adverse events, and optimizing drug doses. Dosage adjustments according to the patient’s genotype for certain drugs and drug classes have been already implemented in relevant clinical guidelines. For example, many pharmacogenomic biomarkers’ genetic variants that demonstrated clinical utility are already incorporated into drug labels. In recent years, personalized management of gastrointestinal disorders based on pharmacogenomics has become a reality. In this chapter, we review the clinical pharmacogenomics of drugs used for the treatment of nonmalignant disorders of the gastrointestinal tract such as proton pump inhibitors, antiemetics, and drugs used to treat inflammatory bowel diseases. For some drugs, such as serotonin 5-HT3 antagonists, proton pump inhibitors, and thiopurines, evidence-based guidelines recommend dosage adjustment according to a patient genotype, while for others, the role of PGx testing to improve therapy outcomes is still a matter of investigation.