Assessment of Potential Drug‐Drug Interactions in Hospitalized Patients With Cardiovascular Diseases at Kenyatta National Hospital, Nairobi, Kenya: A Cross‐Sectional Study

ABSTRACT Background and Aim Drug–drug interactions (DDIs) occur when the pharmacological effect of one medication is altered by the concurrent administration of another, potentially leading to reduced therapeutic efficacy or increased risk of adverse effects. Hospitalized patients with cardiovascular diseases are particularly vulnerable due to complex treatment regimens and polypharmacy. This study aimed to assess the prevalence, severity, and management of potential drug–drug interactions (pDDIs) among cardiovascular inpatients at Kenyatta National Hospital (KNH), Kenya. Methods This retrospective cross‐sectional study included 100 medical records of adult cardiovascular inpatients (hypertension, cerebrovascular accident, coronary artery disease, heart failure) at Kenyatta National Hospital (September 2022–April 2023), selected using systematic sampling. Socio‐demographic, comorbidity, and medication data were extracted using a structured abstraction tool. Potential drug–drug interactions were identified using Lexicomp® and Medscape®. Data were analyzed in SPSS version 20, using descriptive statistics and chi‐square tests to assess associations between patient characteristics and the occurrence of pDDIs. Results Among 100 hospitalized cardiovascular patients (56% male, 44% female; mean age 62.5 ± 10.2 years), a high prevalence of pDDIs was observed, with 91% of patients experiencing at least one interaction (95% CI: 83.8–95.2%). Among affected patients, the majority were classified as moderate severity based on each patient's single most severe interaction (62.6%), followed by minor (24.2%) and severe (13.2%). Hypertension was the most common comorbidity. An exact Freeman‐Halton test showed a statistically significant association between the number of prescribed medications and the occurrence of pDDIs (p < 0.001), with a Cochran‐Armitage trend test confirming a dose‐response relationship (Z = 3.54, p < 0.001), whereas no significant association was observed with age or sex. Commonly prescribed cardiovascular drug combinations, particularly involving antiplatelets, anticoagulants, and antihypertensive agents, were frequently associated with clinically relevant interactions. Conclusion Potential drug–drug interactions are highly prevalent among hospitalized cardiovascular patients at Kenyatta National Hospital, with most interactions requiring monitoring or therapeutic adjustment. Strengthening routine medication review, integrating drug interaction screening tools, and promoting interdisciplinary collaboration may enhance medication safety and optimize patient care in this population.