Clinical Evaluation of Drug–Drug Interactions in Polypharmacy Patients

Polypharmacy, defined as the use of multiple medications by a patient, particularly in elderly or comorbid populations, significantly increases the risk of drug–drug interactions (DDIs). These interactions can lead to altered drug efficacy, increased toxicity, and adverse clinical outcomes, making the clinical evaluation of DDIs crucial in managing polypharmacy patients. This review examines the mechanisms underlying DDIs, including pharmacokinetic interactions (e.g., absorption, distribution, metabolism, and excretion) and pharmacodynamic interactions (e.g., additive, synergistic, or antagonistic effects). We focus on how these interactions impact common polypharmacy scenarios, particularly in managing chronic conditions such as hypertension, diabetes, and cardiovascular diseases. The article explores the role of drug metabolism enzymes (e.g., CYP450 family) and transporters in DDIs, with special emphasis on drugs that are known to significantly alter the pharmacokinetics of other medications. We also discuss current strategies for identifying and mitigating DDIs, such as the use of drug interaction databases, therapeutic drug monitoring (TDM), and dose adjustments. The review highlights the importance of comprehensive medication reviews, patient education, and clinical decision support systems in minimizing risks. Additionally, we examine the challenges and opportunities in applying pharmacogenomics to predict DDIs in polypharmacy patients, aiming to further personalize therapy and reduce adverse drug reactions.