Mixed-Methods Study With a Systematic Review of Personalized Drug Therapy Approaches and Survey Analysis of...

Pharmacogenomics is the study of how an individual's genetic constitution affects their response to drugs. In internal medicine, pharmacogenomics has the potential to transform prescribing practices, making them more precise, effective, and safe for patients. On the other hand, factors that pose barriers to its use include cost implications, limited access to genetic testing, and a lack of strong clinical guidelines. This project seeks to analyze the impact of pharmacogenomics on internal medicine by examining its implications for prescribing, personalized treatment, and the barriers it encounters. It also aims to assess the integration of pharmacogenomics into healthcare systems and to analyze how it can be used to enhance treatment outcomes, minimize adverse drug reactions, and maximize patient protection. A mixed-methods approach was used, combining a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-guided systematic review with a quantitative clinician survey, and including validity, reliability, correlation, and regression analyses. This study was conducted according to PRISMA guidelines and included 23 studies: 15 review articles, five cohort studies, and three case studies. The analysis involved searching all key databases, including PubMed, Scopus, ScienceDirect, and Web of Science, for peer-reviewed articles published from January 2019 to September 2025. The eligibility criteria scoped for the application were based on pharmacogenomics literature in internal medicine, clinical trials, observational studies, and systematic reviews. Exclusion criteria included articles unrelated to pharmacogenomics, publications without peer review, and studies deemed clinically irrelevant. Trends, barriers, and prospective pathways in pharmacogenomics were synthesized from the extracted data. As pharmacogenomics is integrated into clinical practice, it is increasingly applied in drug prescribing, playing prominent roles in predicting medication efficacy, guarding against adverse drug reactions, and tailoring doses for individuals. The application of pharmacogenomics in internal medicine helps refine predictions of therapeutic responses, reduce adverse effects, and "precision" the medicine given, making it a crucial asset for personalized medicine. As a mixed-methods design, generalizability of survey findings is limited by purposive sampling and sample size, although triangulation with systematic review evidence strengthens validity. Constraints such as costs, ethical considerations, and limited clinical applicability hinder the realization of its potential. The results of the study are essential for medical professionals, healthcare system administrators, and researchers interested in applying pharmacogenomics in practice to serve patients optimally.