CYP450 Metabolizer Phenotypes in a Turkish Emergency Cardiac Patient Cohort: A Descriptive Pharmacogenomic Study

Background/Objectives: Cytochrome P450 enzymes (CYP2D6, CYP2C19, CYP3A4) play a key role in interindividual variability in cardiovascular drug metabolism. This study aimed to describe metabolizer phenotype distributions in a Turkish emergency cardiac cohort and across diagnostic categories. Methods: This retrospective descriptive pharmacogenomic study included 250 patients. Genotyping was performed using TaqMan assays for CYP2D6 (*2, *4, *10, *41), CYP2C19 (*2, *17), and CYP3A4 (*22, *1B). Phenotypes were assigned according to CPIC guidelines. CYP2D6 copy-number variation was not assessed. Results: Non-normal metabolizer phenotypes were observed in 55.6% (CYP2D6), 84.4% (CYP2C19), and 30.4% (CYP3A4) of patients. For CYP2D6, normal (44.4%) and intermediate (42.0%) metabolizers predominated. For CYP2C19, intermediate metabolizers were most frequent (36.0%), followed by normal (22.8%), rapid (17.2%), poor (14.8%), and ultra-rapid metabolizers (9.2%). CYP3A4 showed predominantly normal activity (69.6%). Phenotype distributions varied across diagnoses without clear clustering. Conclusions: A high prevalence of CYP2D6 and CYP2C19 variability with predicted functional relevance based on CPIC was observed, whereas CYP3A4 activity was more stable. These findings provide descriptive pharmacogenomic data to support future genotype-guided cardiovascular therapy studies.