FDB Pharmacist-Led Research Sheds New Light on FDA Pharmacogenetics Prescribing Data
Peer-Reviewed Study Published in Annals of Pharmacotherapy Offers New Organized View of Pharmacogenetic Information in FDA Resources
The study, “Characterization of Pharmacogenetic Information in Food and Drug Administration Drug Labeling and the Table of Pharmacogenetic Associations,” was published in the peer-reviewed journal Annals of Pharmacotherapy and is authored by Christine M. Cheng, PharmD; Thomas W. So, PharmD; and Jeff L. Bubp, PharmD, all clinical pharmacists at FDB. Based on analysis of FDA data, the authors created a new categorization schema for pharmacogenetic information and clinical outcomes associated with drug-gene pairs recognized in the FDA resources.
“A plethora of pharmacogenomic information is available from the FDA to support clinician use of genetic test results to optimize drug therapy for their patients,” said Dr. Cheng, the study’s lead author. “Our study attempts to provide an organized view of the types and outcomes of clinically relevant FDA-reviewed pharmacogenetic information. Our methodology can facilitate the evaluation of the ever-growing body of pharmacogenetic knowledge that clinicians use to determine a safe and effective drug and dose for a patient who has relevant genetic test results available.”
Pharmacogenetics Guidance Evolving
There are several prescription drugs where the safety and effectiveness of the medication are known to vary among individuals based on their genetic makeup. One of the earliest examples was warfarin, a prescription blood thinner that requires individualized dosing in order to prevent excessive bleeding or increased clotting. Another example is abacavir, an HIV medication, which can cause potentially life-threatening hypersensitivity reactions including multiple organ failure and anaphylactic shock in patients with a certain genetic variant. For these reasons, all patients must be tested for the high-risk genetic variant before starting abacavir therapy.
In early 2020, the FDA released the Table of Pharmacogenetic (Pgx) Associations, which lists gene-drug interactions that the agency has determined to have sufficient scientific evidence to suggest that there are gene-based differences in drug response. The FDA created the table as the result of some pharmacogenetic testing firms making claims about their tests that were “not adequately supported by sound science,” according to a statement from the agency.
The introduction of the new table prompted FDB pharmacists to compare it to pharmacogenetic information that existed in FDA-approved drug labeling. The authors reviewed labeling for more than 300 prescription drugs used in a variety of therapeutic areas including oncology, psychiatry, neurology, cardiology and infectious disease. Authors then categorized the agency’s guidance across six broad categories: (1) drug disposition including drug metabolism (the way the body breaks down a drug) and drug transport (the way the body moves a drug into cells), (2) drug target, (3) high-risk susceptibility to adverse reactions, (4) therapeutic failure, (5) biomarker-defined indication, and (6) biomarker-defined adverse reactions.
Of the 308 drug-gene pairs studied, authors determined 87% were associated with a gene-based impact on safety, efficacy, or both. The remaining drugs had a possible or theoretical impact on outcomes.
“Although important and clinically meaningful, pharmacogenetics is just one of the many factors that prescribers and pharmacists consider in order to determine a safe and effective medication and dosage for their patients,” Dr. Cheng said. “However, as more pharmacogenetic research is conducted and genetic testing becomes more accessible, we believe that more genetic test results will be included in the electronic health record and available for incorporation into evidence-based clinical decision-making to help optimize patient experiences and outcomes.”
About FDB
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About Hearst Health
The mission of Hearst Health is to help guide the most important care moments by delivering vital information into the hands of everyone who touches a person’s health journey. Each year in the U.S., care guidance from Hearst Health reaches 85 percent of discharged patients, 205 million insured individuals, 103 million home health visits and 3.2 billion dispensed prescriptions. The Hearst Health network includes FDB (First Databank), Zynx Health, MCG, Homecare Homebase and MHK (formerly MedHOK). Hearst also holds a minority interest in the precision medicine and oncology analytics company M2Gen. Follow Hearst Health on Twitter @HearstHealth or LinkedIn @Hearst-Health.