Prevalence and Patterns of Polypharmacy and Potential Drug-Drug Interactions Among Older Adults Attending a Primary Care Center in Iran: A Cross-Sectional Study

Background Polypharmacy, a critical geriatric syndrome, is associated with adverse outcomes like drug-drug interactions (DDIs) and hospitalizations. In Iran, fragmented healthcare may exacerbate its prevalence among older adults. This study aimed to investigate polypharmacy prevalence, predictors, and potential DDI profiles in Iranian older adults in primary care. Methods This retrospective cross-sectional study analyzed electronic health records of patients aged ≥ 65 from an Iranian primary care center. Data included demographics, chronic medications, and potential DDIs identified via Lexicomp®. Polypharmacy and hyper-polypharmacy were defined as 5–9 and ≥ 10 medications, respectively. Statistical analyses included descriptive statistics, chi-square tests, and binary logistic regression. A detailed qualitative DDI analysis was performed. Results The analysis included 230 older adults (mean age 73.5 ± 6.2 years). Polypharmacy prevalence was 68.3%, with hyper-polypharmacy at 22.2%. Each year of age increased polypharmacy odds by 10% (aOR = 1.10, 95% CI: 1.05–1.16, p < 0.001). Gender showed no significant association. Analysis identified 189 unique potential DDI pairs. The most frequent/severe interactions involved Aspirin-NSAIDs and cardiovascular-renal drugs (e.g., ACE inhibitors with potassium-sparing diuretics). Conclusion Polypharmacy and hyper-polypharmacy are highly prevalent among Iranian older adults in primary care and are strongly age-dependent. The high burden of potentially severe DDIs underscores the urgent need for systematic medication reviews and pharmacist-led interventions to optimize prescribing and enhance medication safety in this vulnerable population.