Genotype influences antidepressant discontinuation in a pre-emptive pharmacogenetic testing population.

CYP2C19/CYP2D6 pharmacokinetic phenoconversion

In this retrospective cohort of 5,808 patients enrolled in a preemptive pharmacogenetic testing program, 51% of antidepressants prescribed before PGx testing were discontinued. Multivariate analysis showed a significant association between CYP2C19 increased metabolizer status (ultrarapid + rapid) and higher discontinuation risk for CPIC-recommended drugs (citalopram, escitalopram, sertraline) compared to normal metabolizers (HR = 1.17 [1.08–1.27], p < 0.001). CYP2D6 status was similarly associated with discontinuation for other antidepressants. These findings support preemptive CYP2C19/CYP2D6 genotyping to reduce antidepressant therapy interruptions.

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This study provides concrete evidence of the clinical utility of preemptive genotyping in psychiatry: CYP2C19 status predicts discontinuation, an event often interpreted as treatment failure. With nearly 6,000 patients, the statistical signal is robust. This adds to the growing case for routine preemptive PGx programs in primary care.

Clinical impact: 2/3 · Evidence strength: 2/3 · Novelty: 1/2 · Sample size: 1/1 · Journal quality: 1/1 → Total: 7/10