Tehran University of Medical Sciences Journal of Pharmaceutical Care 2322-4630 13 3 2025 12 01 171 179 EN Mahdiye Abiyarghamsari Department of Clinical Pharmacy, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran Farshad Hoseini-Shirazi Pharmaceutical Sciences Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran Mohammad Sistanizad Department of Clinical Pharmacy, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran 2025 05 04 2025 08 19 Background: Cytochrome P450 2C19 (CYP2C19) exhibits polymorphism, with about 21 known allelic variants. Notably, the *17 allele is associated with increased enzymatic activity, culminating in enhanced CYP2C19 activity and the ultra-rapid metabolizer (UM) phenotype. This genetic variation has a profound impact on an individual's response to a wide range of medications. The primary objective of this study was to ascertain the prevalence of the CYP2C19*17 allele among Iranian patients who have received drug-eluting stents. Methods: This study was conducted to examine the genetic polymorphism of the CYP2C19 enzyme in 100 patients with drug-eluting stents (DESs) at Imam Hossein Hospital, Tehran, Iran. All participants were selected based on pre-defined inclusion criteria. Blood samples were obtained for DNA extraction, and CYP2C19 genotypes were subsequently analyzed through polymerase chain reaction (PCR) and gel electrophoresis. Results: The *17 polymorphism was detected in 11% of the cohort. Of this group, 11 individuals were heterozygous carriers of the CYP2C19*17 allele, whereas the homozygous *17/*17 genotype was not observed in any participant. Conclusion: Our findings demonstrate a low prevalence of the CYP2C19*17 allele and an absence of the homozygous *17/*17 genotype in the Iranian population. Despite its lower prevalence compared to other populations, the clinical implications of this allele are still considered highly significant. https://jpc.tums.ac.ir/index.php/jpc/article/view/837 https://jpc.tums.ac.ir/index.php/jpc/article/download/837/428