Genetic Testing for Clopidogrel

R. David Anderson, M.D., and Julie A. Johnson, Pharm.D., review an alert that appears in a cardiac patient’s electronic medical record when genetic results suggest a prescribed drug may not be effective. (Photo by Jesse Jones/University of Florida)

R. David Anderson, M.D., and Julie A. Johnson, Pharm.D., review an alert that appears in a patient’s electronic medical record when genetic results suggest a prescribed drug may not be effective. (Photo by Jesse Jones/University of Florida)

Interventional cardiologists at UF Health order a CYP2C19 genetic test through the UF Health Personalized Medicine Program and UF Health Pathology Laboratories to help determine the right medicine and the right dose to reduce a patient’s risk of blood clots forming. The test is often ordered when patients have a stent placed in a blood vessel of the heart, but it may also be ordered in other situations.

Clopidogrel (Plavix®) is a medication that prevents blood cells from sticking together and forming a harmful clot. It can be given to reduce the risk of heart attacks or strokes in some individuals. For clopidogrel to work, a protein in the body called CYP2C19 (pronounced “SIP-2-see-19”) has to help convert the medication to an active form. This protein works faster or slower depending on a patient’s genetics. If the protein works slower, clopidogrel might not work as well as it should. In 2009, the U.S. Food and Drug Administration added a warning about these genetic factors to the drug’s label.

The UF Health Personalized Medicine Program collaborated with the interventional cardiology team at UF Health Shands Hospital to implement this test as a routine part of patient care in June 2012. The clinical lead for the collaboration is R. David Anderson, M.D., FACC, FSC.

Of the more than 1,000 interventional cardiology patients tested during the first year of the program, approximately 28 percent had a genetic variation for which a different medication is recommended. Among the 291 patients who went on to have a stent placed in the heart, 80 patients had a genetic variation and were eligible for a medication change. A total of 56 of these individuals had their medication switched as a result of the genetic testing.

Information on Genetic Testing for Clopidogrel (Plavix)