Background: Older adults are more likely to have multiple chronic diseases, leading to simultaneous use of many medications. This situation results in increased drug-related problems (DRPs) which causes of adverse health outcomes. Objective: The aim of study was to assess the prevalence and associated risk factors of DRPs among older adults admitted to a tertiary care hospital. Methods: We conducted a cross-sectional study involving 357 participants age > 60 years admitted to Ramathibodi Hospital during February 1st to November 30th 2022. Participants were evaluated for baseline characteristics, medications and DRPs. The participants were classified into two groups according to their exposure to DRPs: “exposure to >1 and ≤ 1 criteria of DRPs”. Multivariate logistic regression analysis was performed to identify the independent predictors of exposure to > 1 DRPs. Results: Overall, 205 (57.4%) exposed to >1 criteria of DRPs. Over a half of populations experienced at least one potentially inappropriate medications (PIMs) [242; 67.8%] and potential drug-drug interactions (pDDIs) [256; 71.7%]. Adverse drug reactions (ADRs) were considered to be the cause of hospital admission in 27 patients (7.6%). Polypharmacy and the use of proton pump inhibitors, hypoglycemics, diuretics, psycholeptics, psychoanaleptics and cardiac therapy medications were greater risks of exposure to > 1 criteria of PPI, DDI or ADR. Conclusion: The risk factors associated with exposure to > 1 criteria of PPI, DDI or ADR were specific types of medications and polypharmacy. Therefore, comprehensive medication reviews and careful medication prescriptions in geriatric population should be recommended.

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