Assessment of Potential Drug–Drug Interactions and Associated Factors Among Pulmonary Inpatients in a Tertiary Care Hospital: A Cross-Sectional Study

BACKGROUND: Potential Drug-drug interactions (pDDIs) are a significant cause of adverse drug events and can compromise treatment outcomes, especially in hospitalized patients who are prescribed multiple medications. Pulmonary patients are especially vulnerable due to polypharmacy and the presence of multiple co-morbid conditions. This study aimed to determine the prevalence of pDDIs and identify associated risk factors among hospitalized pulmonary patients. METHODS: A cross-sectional study was conducted among pulmonary patients admitted to a tertiary care hospital in Nepal between July 2024 and December 2025. Patients with a hospital stay of ≥ 24 h and receiving two or more medications were included. Data on socio-demographics, clinical conditions, and medications were collected using a structured form. pDDIs were identified using Lexicomp and IBM Micromedex. Descriptive statistics, bivariate analysis, and binary logistic regression were performed using SPSS V16, with p < 0.05 considered statistically significant. RESULTS: Out of 377 patients who met the inclusion criteria, Lexicomp and Micromedex identified 36.1% and 19.9% pDDIs, respectively. A moderate agreement was observed between Lexicomp and Micromedex in identifying pDDIs (Cohen's Kappa = 0.547). Micromedex classified most interactions as major (53.33%), while Lexicomp classified 66.18% as major severity; however, these classifications were based on screening databases and not confirmed clinical adverse events. Polypharmacy, longer hospital stays, presence of co-morbidities, alcohol consumption, and advanced age were significantly associated with an increased risk of pDDIs. CONCLUSION: pDDIs are prevalent among hospitalized pulmonary patients and are closely linked to polypharmacy and complex clinical profiles. Routine medication review and the use of drug interaction screening tools are essential to minimize the risk of harmful interactions.