As a healthcare professional, are you aware of the pharmacogenomic information on FDA-approved drug labels?
Pharmacogenomic information can appear in different sections of the labeling depending on the actions. Drug labeling may contain information that describes risk for adverse events, drug exposure and clinical response variability along with many other things.
The FDA has a number of drugs with pharmacogenomic labeling. Below are a few that are prevalent in elderly patients.
Clopidogrel:
Taken by about 40 million patients worldwide, is used to prevent atherothrombotic events and cardiac stent thrombosis when given along with aspirin. Clopidogrel is activated by CYP2C19.
The FDA-approved drug label for clopidogrel (Plavix) warns that patients who are CYP2C19 poor metabolizers may have diminished effectiveness of the drug, leading to higher cardiovascular event rates following acute coronary syndrome or percutaneous coronary intervention, as compared to patients with normal CYP2C19 function. The drug label suggests that alternative treatment or treatment strategies are considered in patients identified as CYP2C19 poor metabolizers.
Excerpt from the Clopidogrel (Plavix) drug labeling:
The effectiveness of Plavix is dependent on its activation to an active metabolite by the cytochrome P450 (CYP) system, principally CYP2C19…Plavix at recommended doses forms less of that metabolite and has a smaller effect on platelet function in patients who are CYP2C19 poor metabolizers. Poor metabolizers with acute coronary syndrome or undergoing percutaneous coronary intervention treated with Plavix at recommended doses exhibit higher cardiovascular event rates than do patients with normal CYP2C19 function. Tests are available to identify a patient’s CYP2C19 genotype; these tests can be used as an aid in determining therapeutic strategy. Consider alternate treatment or treatment strategies in patients identified as CYP2C19 poor metabolizers. pharmgkb.org
Codeine:
Codeine also depends on the CYP2D6 gene, as it must be activated to its more potent opioid metabolites, including morphine. Poor CYP2D6 metabolizers do not benefit from codeine therapy.
Codeine is an opiod analgesic pro-drug, typically used for pain relief. It is metabolized by CYP2D6 into morphine, which is the active drug form. CYP2D6 poor and ultra-rapid metabolizers may experience different efficacy.
Excerpt from the codeine sulfate drug label:
Some individuals may be ultra-rapid metabolizers due to a specific CYP2D6*2×2 genotype. These individuals convert codeine into its active metabolite, morphine, more rapidly and completely than other people. This rapid conversion results in higher than expected serum morphine levels. Even at labeled dosage regimens, individuals who are ultra-rapid metabolizers may experience overdose symptoms such as extreme sleepiness, confusion, or shallow breathing.
For a complete list of Pharmacogenomic Biomarkers in Drug Labeling, go to FDA
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For more information on our metabolic validation, via pharmacogenomic testing, contact:
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Source: FDA, ncbi, pharmgkb.org