Clinical Guidance

When it comes to prescribing drugs and evaluating patients for potential drug interactions, pharmacogenetic testing is no longer a future consideration.

  • The American Medical Association advocates that physicians become familiar with genetic variations that can affect patients’ drug metabolism, and be able to recognize when testing should be used to inform prescribing.
  • The U.S. Food and Drug Administration currently recommends testing in specific instances (to determine the starting dose for warfarin, for example), and is laying the groundwork for routine testing in early phase clinical drug trials.
  • A report from the U.S. Department of Health and Human Services states: “Pharmacogenetic testing for potential adverse drug events (ADEs) or ineffective drug responses may reduce health care costs over the long term by diminishing the duration and severity of illness and the costs associated with ineffective treatment and avoidable ADEs.”

Genelex DNA pharmacogenetic testing powered by YouScript is the alternative to “one size fits all” drug prescribing that can lead to potentially serious side effects, treatment failure, and poor patient compliance. Pharmacogenetic testing combined with the YouScript Precision Prescribing Software reveals drug-metabolizing gene variants—found in more than one-half of patients—to help physicians and pharmacists determine the appropriateness and dosage of commonly prescribed drugs such as beta blockers, opioid analgesics, and warfarin.

The Role of Genetics in Drug Metabolism

Virtually every pathway of drug metabolism, transport, and action is susceptible to genetic influence. It is estimated that 20%-95% of an individual’s variation in drug response is based on genetics. Among the top-selling prescription drugs, 59% of the 27 medicines most frequently cited as leading to ADEs are metabolized by at least one enzyme known to have gene variants that code for reduced-functioning or non-functioning proteins.

Healthcare providers can account for factors such as age, physiologic function, and concomitant disease, but patient genotype remains a major unknown in most drug prescribing. All too often, this results in an ADE.

ADE risk increases exponentially in patients taking 4 or more drugs. Polypharmacy is common in patients with cancer, cardiovascular disease, chronic pain, diabetes, and psychiatric conditions. Patients with chronic medical conditions taking multiple medications – in particular, those over 65 years of age – face the highest ADE risk.

Pharmacogenetic Testing

Pharmacogenetic testing powered by YouScript provides information on the highly polymorphic cytochromes CYP2D6, CYP2C9 (includes VKORC1), CYP2C19, CYP3A4, and CYP3A5. Knowing a patient’s unique genetic make-up enables physicians to:

  • Individualize patient therapies
  • Optimize the safety and efficacy of prescription regimens
  • Improve treatment compliance, especially in patients requiring long-term or multi-drug therapy
  • Minimize liability by reducing “trial and error” prescribing
  • Keep their practice current with the latest advances in genetic science