Pharmaceuticals play an important role in healthcare disease management strategies, and represent one of the primary tools used by physicians in treating patients. A major advance that has recently burst onto the healthcare landscape to help physicians prescribe safer and more effective medications for their patients is pharmacogenetic (PGx) testing. This simple and easy testing strategy can analyze a patient’s genetic makeup and accurately predict which pharmaceuticals have the highest likelihood of being effective, and at what dose.
Why is PGx testing important for physicians, their practices and their patients?
In the United States, there are over 2 million adverse drug reactions (ADR’s) per year, with 106,000 of those resulting in death. ADR’s are reported to be the fourth leading cause of death in the United States and cost as much as $136 billion dollars annually. The larger number of drugs a patient takes, the higher the risk of an ADR. Patients taking over 11 drugs have a 96% chance of an ADR, and the average Medicare patient is on 5-8 drugs.
A growing body of PGx studies has provided overwhelming evidence regarding the influence of genetic variations on drug responses. PGx testing analyzes the genes responsible for regulating the drug metabolizing pathways and predicts: 1) how individuals are likely to respond to a variety of commonly prescribed drugs; 2) what dosage level is needed, based on the speed with which drugs are broken down; and 3) whether or not a patient is at risk of an ADR. A simple and convenient non-invasive cheek swab is easily collected in the physician office and submitted to the lab for PGx testing.
The PGx test need only be administered once to obtain the patient’s DNA “fingerprint” that predicts their drug-metabolizing profile; this can support the safest and most effective prescribing of some of the most common drugs prescribed by physicians throughout a patient’s lifetime. Awareness of a patient's unique genetic makeup that can predict the response to certain drugs can help physicians decide which type of drug therapy may be most appropriate and most effective for patients, and can also help the physician avoid drugs and drug combinations that may cause ADR’s.
What clinical value should a physician expect from PGx testing?
With advances in medicine, the future of healthcare is heading toward having physicians provide more personalized medicine, especially with regard to prescription drug therapy. Until recently, drugs had been developed with the idea that each drug works pretty much the same in all individuals. But genomic research has changed that “one size fits all” approach and has opened the door to more sophisticated prescribing practices.
PGx testing will surely become part of the standard of care regarding the use of pharmaceuticals, since testing will provide physicians critical new information that will help:
- produce a safer and more effective approach to drug therapy
- reduce the risks of side effects and overdose
- minimize adverse drug reactions and drug-drug interactions
- physicians choose an optimal dose to improve clinical outcomes
- reduce exposure to liability and litigation related to drug prescribing
The FDA has established a compilation of over 150 medications that include warning labels regarding pharmacogenetic variations. This list includes a wide range of some of the most commonly prescribed medications, and according to the FDA, "pharmacogenomics can play an important role in identifying responders and non-responders to medications, avoiding adverse events and optimizing drug dose."
The FDA indicates that this type of drug labeling contains information on genomic biomarkers that can indicate:
- drug exposure and clinical response variability
- risk for adverse events
- genotype-specific dosing
- mechanisms of drug action
- polymorphic drug target and disposition genes
The Clinical Pharmacogenetics Implementation Consortium (CPIC), formed in 2009, was established because, according to CPIC, "one barrier to the clinical implementation of pharmacogenetics is the lack of freely available, peer-reviewed, updatable, and detailed gene/drug clinical practice guidelines.” CPIC provides guidelines for translating genetic test results into appropriate prescribing practices for specific drugs. CPIC guidelines can help clinicians use genetic test results to optimize drug therapy.
A key assumption underlying the CPIC guidelines is that pre-emptive (pre-prescription) genotyping will rapidly become more widespread, and that clinicians will be faced with having patient genotypes available, even if they have not explicitly ordered a test with a specific drug in mind.
Who should physicians test?
It would be prudent and valuable for physicians to test any patient who:
- requires a higher-than-standard dose to achieve the desired result
- has had a severe adverse drug reaction
- has had unexpected or unexplained responses to medications
- has had multiple unsuccessful drug trials
- has health issues in multiple organ systems
- has had multiple drug types prescribed
With the recent emphasis on delivering more personalized medicine, PGx testing is here to stay because it can contribute so much to physicians and their patients. As physicians understand the use of patient-specific DNA profiles, this will help fundamentally guide medication selection and dosing. Many of our nation's top-tier clinical institutions now use PGx testing as a valuable new addition to their knowledge base, because physicians can harness specific genetic information to individualize drug therapy. This helps physicians be even more effective in their prescribing practices, and provides a win-win for them and their patients.
The promise that PGx testing fulfills is to provide physicians and their patients with the right information, the right drug, the right dose, right from the beginning. It is gratifying when the drug prescribing practice of physicians can be fine-tuned to benefit their patients through the use of a simple, yet powerful new tool - pharmacogenetic testing*.