Pharmacogenomics: The right med, the right dose, every time

For pharmacists who want to “practice at the top of their license,” pharmacogenomics (PGx) offers an opportunity whose time has come, said Rebecca W. Chater, RPh, MPH, FAPhA, and Brad Tice during“Precision Medicine: Integrating Genomics into Pharmacy Practice,” their recent presentation at the NACDS Total Store Expo.

Citing projections that by 2020, 75% of all healthcare payments will be value-based, Chater, an executive healthcare strategist at Raleigh-based Ateb Inc., called this scenario a "tremendous opportunity for the community pharmacist to take the lead in pharmacogenomic testing and precision medicine.” 

Top pick: Pharmacogenomics could boost community pharmacy sales

Rebecca ChaterShe continued, “If medication use were thought of as a disease, it would be the fourth leading cause of death in the U.S.” Ineffective drug therapy occurs at a staggering rate of up to 75% with medications prescribed for conditions such as depression, asthma, diabetes, arthritis, Alzheimer’s disease, and cancer, she said, and most often is due to genetic variations in the patients taking these drugs.

“We know that four out of five people have genetic variations that impact how their bodies process drugs, and these common variances affect metabolism of at least 150 common prescription medicines. Due to poor metabolism, some people require a lower dose than usually recommended, while others are rapid metabolizers and need a higher than normal dose of medicine; others experience toxicity and cannot take the medication at all. Pharmacogenomics allows us to accurately predict this response and get the medication right the first time,” she said.

Precision therapies

The terms pharmacogenomics, pharmacogenetics, personalized medicine, and precision medicine are virtually interchangeable and reflect a personalized approach to medication use based on the premise that “one size does not fit all.” The terms are used “to convey a process of leveraging actionable information gained from the study of an individual’s genetic makeup as the key to safe and effective medication use,” said Chater.

See also: Genomic testing for warfarin therapy

She cited two examples of genomic variances, CYP2D6 and CYP2C19, as important mutations. Among individuals with the first variance, 5%-10% may be poor metabolizers of codeine, for whom the pain medicine has no effect. In the case of the latter variance, three out of 10 people who are prescribed the antiplatelet medication clopidogrel cannot convert the drug to its active form and derive no benefit at all.

“The downstream cost-avoidance from detecting patient-specific genetic mutations that impact medication use and making the necessary changes to ensure that therapy is tailored to be safe and effective at the individual patient level is a game-changer,” said Chater, “and presents a new frontier in pharmacy practice.”

Destination: Pharmacy

In light of the fact that costs connected with genetic testing have dropped significantly, pharmacogenomic testing is a service that further strengthens pharmacy’s position as a healthcare destination, said Chater.

“Pharmacies already offer patient care services such as medication therapy management, vaccinations, point-of-care testing, and adherence solutions. Pharmacogenomics is a natural extension of these services. Pharmacists have a unique role here as the one healthcare professional who knows and understands the entire scope of medications a patient is taking and is qualified to recommend appropriate drug-therapy changes.”

Chater encouraged members of the profession to take advantage of educational courses, professional membership learning courses, and industry opportunities for collaboration that will help them to facilitate and adopt PGx.

“Pharmacogenomics is an opportunity to truly transform patient care as it relates to medication use. Genomic testing, in its full scope, can allow us to provide patients the right medication, at the right dose, every time.”

Barbara Hesselgrave is a freelance writer in Baltimore, Md.

Genomic testing in the pharmacy

Genomic testing involves a simple cheek swab of the patient that the pharmacist sends to a qualified laboratory. Using very sophisticated equipment, the patient sample undergoes testing by exposure to various chemical and biological agents. Analysis of the reactions confirms variances (mutations) in the DNA. These mutations are identified as altered genetic pathways on specific genes, and when compared to a set of standards, help the pharmacist and physician, working together, to make the best informed medication choices for that individual’s therapy.
- Barbara Hesselgrave