A recent Community Pharmacy Foundation (CPF) project delved into the fascinating world of pharmacogenomics. Stephanie Davis, PharmD, BCACP, part-owner of Goodrich Pharmacy in Anoka, Minnesota, worked on the project with Elise Durgin, PharmD, BCPS, and Emily Hulke, PharmD, who were residents at the time.

Davis and her team have collaborated with CPF in the past and generally participate in many projects. “We had the idea to perform and interpret pharmacogenomic testing, and when we have a new idea and need help financially or with a collaboration, we reach out to CPF for a grant and to make sure the program is sustainable,” she explained.

Initially, the plan was for a 12-month study on pharmacogenomic testing in patients taking opioids. However, at the 9-month mark, only 3 patients had enrolled in the study. Davis explained that some of these patients were afraid that their test results would lead to their physician taking away their opioids.

With CPF approval, the team decided to shift their focus to mental health care, which attracted many referrals from primary care providers in the area. Candidates were patients who were unsatisfied with their mental health treatment due to adverse effects (AEs) or ineffective medications.

How did the process work? Hulke explained that after receiving a referral for pharmacogenomic testing, she set up an initial appointment with the patient. During this appointment, the pharmacist or resident performed a full comprehensive medication review, including current medications and previous medications and what occurred when the patient took these medications.

Althouh pharmacogenomic testing might not reveal all of their answers, the team explained to patients that it could provide a piece to the puzzle in helping to identify the most appropriate medication. After obtaining consent, they took a cheek swab from the patient and sent the sample to OneOme for testing. 

The resulting lab report provides information on the genes that may affect how the patient responds to certain medications. For example, in an ultrarapid metabolizer of a particular enzyme, a drug metabolized by that enzyme may not work, or the patient may need higher doses to achieve the desired response. On the other hand, a poor metabolizer may have an increased risk of AEs.

For example, citalopram is metabolized by cytochrome P450 (CYP) 2C19, which reduces activity in the body. An ultrarapid metabolizer of CYP2C19 would have lower levels of citalopram in the plasma and thus a higher probability of medication failure with citalopram. On the other hand, a CYP2C19 poor metabolizer would have higher levels of citalopram in the plasma, and patients would be more likely to experience AEs from this medication.

The pharmacists and residents would consider the patient’s entire profile, looking at enzyme pathways for all of their medications, and provide the report, along with a recommendation, to the patient’s physician. The results of the testing were also discussed with each patient individually.

The results of the project varied. “The majority of patients liked having this information. It made them not feel like guinea pigs––like there was more information being used to decide which medication they should take rather than just throwing different medications at them,” Hulke explained. “They felt empowered and wanted to know more, even if the reports didn’t show exactly what they wanted or expected.” Moreover, the physicians were grateful for the information and interpretation of results, and many patients ended up on a different medication as a result of the report and recommendation.

Insurance coverage for the test kit varied, as did coverage for the interpretation, which could be billed as an office visit or medication therapy management (MTM) visit. Goodrich Pharmacy pharmacists are hopeful that billable opportunities will increase in the future.

Even though the grant has ended, the pharmacists at Goodrich Pharmacy still offer pharmacogenomic testing services and interpretation. In addition to adults, they have had an increasing number of referrals for pediatric patients with attention deficit hyperactivity disorder.

In addition to gaining a wealth of knowledge about mental health medications, the pharmacists and residents learned about other drugs from pharmacogenomic testing, too. For example, “[clopidogrel (Plavix)] is a prodrug that is converted to its active metabolite through the 2C19 pathway,” Davis explained. “In patients who are poor metabolizers of 2C19, [clopidogrel] would not be as effective, leading to a higher risk of cardiovascular events. The patient would have to take [ticagrelor (Brilinta)] or a different antiplatelet medication.”

Hulke mentioned that many medications could be affected by enzymes, such as warfarin, which is metabolized by multiple enzymes, and protein pump inhibitors like omeprazole. However, there isn’t always a change in medication therapy that is recommended because of this.

Can pharmacists apply pharmacogenomics to their practice? Absolutely, but it may take a lot of studying, Davis and Hulke said.

They recommend obtaining a pharmacogenomics certificate, which can be done through programs such as the National Association of Chain Drug Stores’ “Test2Learn” program. Pharmacists can also attend conferences and classes on the topic for more information. By doing so, pharmacists can help patients make sure their medications are working based on genetics.

Davis and Hulke have a call to action for pharmacists. “Never stop learning. Pharmacogenomics is a great service we can offer to our patients,” Davis said.

“If you are interested in and passionate about pharmacogenomics, take the time to learn about it and consider offering it as a service to your patients,” Hulke added.

The Community Pharmacy Foundation (CPF) funds innovative ideas to advance the practice of pharmacy in the community setting. CPF is committed to transforming community-based pharmacy practice beyond filling prescriptions to a focus on providing patient care as a founding sponsor of the national Flip the Pharmacy program.