Pharmacogenomics in Personalized Therapy: How Genetic Testing is Redefining Drug Safety and Efficacy

Background The field of pharmacogenomics (PGx) deals with the study of the impact of genetic variability on drug responsiveness. PGx serves as the scientific backbone of personalized medicine, providing clinicians with the ability to choose appropriate treatments for patients in accordance with their genetic make-up, thus minimizing the risk of adverse drug events (ADEs). Objective To present a systematic review of the scientific evidence on the scientific basis, clinical utility, safety considerations, barriers to implementation, and the future of pharmacogenomics across various medical fields. Methods Narrative review of peer-reviewed articles written between 2000 and 2024, from such databases as PubMed, Scopus, Embase, Web of Science, and Google Scholar. Results Clinical variation in drug metabolism is caused by polymorphisms in the genes that code for CYP450 enzymes (CYP2D6, CYP2C19, CYP2C9) and other pharmaco genes. Several important gene/drug combinations such as CYP2C19/clopidogrel, VKORC1CYP2C9/warfarin, HLA-B*57:01/abacavir, CYP3A5/tacrolimus, and TPMT/azathioprine have CPIC-approved guidelines for pharmacogenomics. PGx-based prescriptions reduce the need for trial and error, reduce ADR frequency, and improve treatment efficacy in oncology, psychiatry, cardiology, infectious disease management, and transplantation. The recognition by the regulatory authorities is increasing, with FDA including PGx biomarkers in the label of hundreds of drugs. Some challenges that exist include lack of clinician education, absence of standard guidelines, lack of EHR integration and ethical issues regarding genetic privacy and discrimination. Conclusion Pharmacogenomics is changing the approach to medication prescriptions from one based on populations towards individually-tailored genetic prescriptions. Integration into clinical practice, along with AI, EHR, and standardized guidelines will be necessary.