Prescribing prevalence and trends of medications with pharmacogenetic implications: a study based on primary care data in Manitoba, Canada

Aims To characterize prescribing prevalence and temporal trends of medications with pharmacogenetic (PGx) implications in Manitoba primary care and identify frequently implicated pharmacogenes.Methods We conducted a retrospective, repeated annual analysis of electronic medical record data from the Manitoba Primary Care Research Network (MaPCReN) between 2017 and 2021. Prescribing patterns and unadjusted relative risks (RRs) according to demographic characteristics were assessed.Results Among 223,630 eligible patients, 42.4% received ≥ 1 medication with PGx implications. Greater exposure was observed among adults aged ≥ 65 years (RR 1.75, 95% CI 1.74–1.77), females (RR 1.24, 95% CI 1.23–1.26), and rural residents (RR 1.23, 95% CI 1.22–1.25) (all p < 0.0001). The aggregate prescribing prevalence of the 10 most common medications with clinically actionable PGx recommendations decreased by 8.0% from 2017 to 2021 (p < 0.001). Pantoprazole (+55.4%) and sertraline (+30.0%) increased, whereas codeine (−33.2%), citalopram (−26.5%), and omeprazole (−20.6%) declined. Frequently implicated pharmacogenes included CYP2D6, CYP2C19, CYP2B6, SLCO1B1, and ABCG2.Conclusions Medications with PGx implications were commonly prescribed within MaPCReN. These patterns may inform future studies evaluating PGx testing in Manitoba primary care.