ArticlePharmacogenetics and genomics2019
Assessing the clinical impact of CYP2C9 pharmacogenetic variation on phenytoin prescribing practice and patient response in an integrated health system.
Article in Pharmacogenetics and genomics, 2019. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 11 papers, 1 of them a synthesis that pooled it.
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
11 citing papers in PubMed, 1 synthesis or guideline pooled it.
- Pharmacogenetic Variants and Plasma Concentrations of Antiseizure Drugs: A Systematic Review and Meta-Analysis.JAMA network open · 2024Pooled it
- Pharmacogenomics in epilepsy care across Asia.Epilepsia · 2026Review
- Association of decreased CYP2C9 function,Frontiers in pharmacology · 2026Article
- Model-based clinical utility of pharmacogenetic testing and its potential population impact on the use of essential medicines in Zimbabwe.Frontiers in pharmacology · 2026Article
- Sources of pharmacokinetic and pharmacodynamic variability and clinical pharmacology studies of antiseizure medications in the pediatric population.Clinical and translational science · 2024Review
- Exome sequencing allows detection of relevant pharmacogenetic variants in epileptic patients.The pharmacogenomics journal · 2022Article
- Analyzing Precision Medicine Utilization with Real-World Data: A Scoping Review.Journal of personalized medicine · 2022Article
- Review
- Participation of Monocarboxylate Transporter 8, But Not P-Glycoprotein, in Carrier-Mediated Cerebral Elimination of Phenytoin across the Blood-Brain Barrier.Pharmaceutical research · 2021Article
- Associations of CYP2C9 and CYP2C19 Pharmacogenetic Variation with Phenytoin-Induced Cutaneous Adverse Drug Reactions.Clinical and translational science · 2020Article
- Emerging strategies to bridge the gap between pharmacogenomic research and its clinical implementation.NPJ genomic medicine · 2020Review
Corrections and comments
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Authors and funding
10 authors.
Funding
Abstract
objectiveTo assess the impact of CYP2C9 variation on phenytoin patient response and clinician prescribing practice where genotype was unknown during treatment.
methodsA retrospective analysis of Resource on Genetic Epidemiology Research on Adult Health and Aging cohort participants who filled a phenytoin prescription between 1996 and 2017. We used laboratory test results, medication dispensing records, and medical notes to identify associations of CYP2C9 genotype with phenytoin blood concentration, neurologic side effects, and medication dispensing patterns reflecting clinician prescribing practice and patient response.
resultsAmong 993 participants, we identified 69% extensive, 20% high-intermediate, 10% low-intermediate, and 2% poor metabolizers based on CYP2C9 genotypes. Compared with extensive metabolizer genotype, low-intermediate/poor metabolizer genotype was associated with increased dose-adjusted phenytoin blood concentration [21.3 pg/mL, 95% confidence interval (CI): 13.6-29.0 pg/mL; P < 0.01] and increased risk of neurologic side effects (hazard ratio: 2.40, 95% CI: 1.24-4.64; P < 0.01). Decreased function CYP2C9 genotypes were associated with medication dispensing patterns indicating dose decrease, use of alternative anticonvulsants, and worse adherence, although these associations varied by treatment indication for phenytoin.
conclusionCYP2C9 variation was associated with clinically meaningful differences in clinician prescribing practice and patient response, with potential implications for healthcare utilization and treatment efficacy.
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