The field of pharmacogenomics was established in the 1950s, but physicians and pharmacists have long been aware of the subtle differences in drug response between patients.[i]
By John Papastergiou, BSc, BSc Phm
Photo by Brandon Gray
Inter-patient variability in drug response can result in lack of efficacy, intolerance, or even serious adverse reactions (ADRs). Severe ADRs have become the fourth leading cause of morbidity and mortality in the developed world.[ii] In Canada alone, there are an estimated 200,000 severe ADRs annually, with 5-10% being fatal. One-fourth of general admissions to Canadian hospitals are drug related, and 70% of those are thought to be preventable. This costs the healthcare system a staggering $17 billion each year.[iii]
It is routine for physicians and pharmacists to consider factors such as age, body mass, renal function and drug interactions in an attempt to avoid unintentional drug consequences. Nonetheless, genetic factors alone can account for anywhere between 20 and 95% of the variability in drug response.
These factors often go unrecognized[iv] and, historically, there was no easy way for clinicians to screen or assess patients for these differences. It was not until very recently that the technology for pharmacogenetic testing has been made available to practitioners in frontline clinical settings. This availability, in combination with the pharmacist’s expertise in pharmacology and kinetics, makes pharmacists ideally suited to champion implementation of this novel technology in order to optimize therapy. In fact, the ASHP recently published a position statement on the pharmacist’s role in clinical pharmacogenomics and challenged pharmacists to take the lead in this area.[v]
In response to this, a talented group of community pharmacists has set out to be the first to evaluate the feasibility of implementing personalized medication services into community practice and to quantify the type of drug therapy problems identified as a result of screening. In order to do this, the team partnered with an industry leader in pharmacogenomics, GeneYouIn Inc.
The unique collaboration between community pharmacist and geneticists led to the initiation of the ICANPIC (Innovative Canadian Pharmacogenomic Screening Initiative in Community Pharmacy) Study. The full results of the study are expected to be published later this year, but a snapshot of the preliminary results was presented at this years’ Canadian Pharmacists Conference in Calgary.
The study was designed as open-label, non-randomized, and observational. Two community pharmacies in Toronto, Ont. offered pharmacogenomic screening as part of their professional services program. Before initiation, participating pharmacists received structured, comprehensive training in pharmacogenetics. Pharmacists then facilitated voluntary subject enrolment among patients who they believed would benefit from screening and met inclusion criteria. Eligible patients received a simple buccal swab followed by DNA analysis using PillCheck®.
PillCheck® is Geneyouin’s proprietary genotyping assay that translates genomic data and generates a personalized, evidence-based, report that provides insight into patients’ inherited drug metabolic profile. Upon receiving the report, pharmacists invited patients back to the clinic for interpretation of the results. Clinically significant drug therapy problems were identified and recommendations for medication optimization were forwarded to the primary care physician.
One hundred patients were enrolled in the study. Average age was 57.4 years, and patients were taking a mean of 5.6 chronic medications. Pharmacists cited the most common reasons for testing as ineffective therapy (44.6%), to address an adverse reaction (35.5%), and to guide initiation of therapy (11.8%). An average of 1.3 drug therapy problems were identified per patient. Pharmacist recommendations included change in therapy (57.1%), dose adjustment (14.3%), discontinuation of a drug (7.1%), and increased monitoring (19.6%). Generally, physician feedback was positive, but did reveal an opportunity for a broader understanding of the technology.
The results of this novel study highlight the readiness of community pharmacists to adopt pharmacogenetic screening into practice and their ability to leverage this technology to positively impact medication management. The team’s findings suggest that community pharmacists are ideally suited to offer both personalized medication services and interpretation of genomic results.
[i]ScottSA. Personalizing medicine with clinical pharmacogenetics. Genet Med. 2011; 13(12): 987–995
[ii]Lazarou J, Pomeranz B, Corey PN. Incidence of adverse drug reactions in hospitalized patients: A meta-analysis of prospective studies. JAMA 1998;279:1200–1205.
[iii] University of British Columbia – Centre for Molecular Medicine and Therapeutics. Genetic Contributions to Adverse Drug Reactions. Available at: www.cmmt.ubc.ca/research/investigators/hayden/projects/adr. Accessed July 25, 2016
[iv]Evans WE, McLeod HL. Pharmacogenomics–drug disposition, drug targets, and side effects. N Engl J Med. 2003;348(6):538–549
[v]American Society of Health-System Pharmacists.ASHP statement on the pharmacist’s role in clinical pharmacogenomics. Am J Health-Syst Pharm. 2015; 72:579–81
John Papastergiou, BSc, BSc Phm is head of the research study examining how to help more patients achieve enhanced outcomes by using their prescription meds more effectively. He is also is a pharmacist-owner of two Shoppers Drug Marts in Toronto, Assistant Professor at the Leslie Dan Faculty of Pharmacy, University of Toronto, and Adjunct Professor at the School of Pharmacy, University of Waterloo.