A Lesson in Pharmacogenomics

Pharmacogenomics, known as the study of how human genes affect a person’s response to medication, blends pharmacology (the study of drugs) with genomics (the study of genes and their functions). This combination aids in the development of safe, effective medication therapy and doses that are tailored to each individual’s genetic makeup. Medicine is not “one size fits all,” and it is difficult to predict who may benefit from specific medicine, who will not respond, or who may experience adverse side effects.

The Human Genome Project helped researchers learn a great deal about how these inherited genes affect response to medication. The observed differences in genetic makeup can help predict which patients will benefit or be harmed by different medication regimens. Although pharmacogenomics is still a somewhat novel idea, new studies are continuously being conducted. In the future, researchers hope to develop tailored drugs for conditions such as cardiovascular disease, Alzheimer’s Disease, cancer, HIV/AIDs, and asthma.

Doctors are beginning to use genetic information to prescribe certain medications; however, tests are limited to very few health conditions due to both cost and lack of experience. For example, before prescribing abacavir (Ziagen) for patients with HIV (Human Immunodeficiency Virus), doctors routinely test for a genetic variant that makes them more likely to experience a severe reaction. This testing could prevent adverse reactions from the drug which could lead to potential hospitalization.


Pharmacogenomics has already proven beneficial in several types of cancer. Trastuzumab (Herceptin) is now only given to women with breast cancer tumors that overproduce the HER2 protein. The FDA recommends genetic testing before giving the chemotherapy drug mercaptopurine (Purinethol) in acute lymphoblastic leukemia patients. Some patients with a genetic variant are unable to process the drug, leading to severe side effects and increased risk of infection. FDA also recommends testing colon cancer patients before receiving irinotecan (Camptosar) because certain patients do not clear the drug from the body quickly enough, leading to severe diarrhea.

Pharmacogenomics is revolutionizing the field of medicine as we know it today. Research is ongoing, and the future of pharmacogenomics is promising.

At Mac’s LTC Pharmacy Solutions, we love to educate and inform consumers. If you would like to sign up for any on-site educational classes or clinics, contact us today!