Drug-drug interaction, adverse drug reaction and their determinants among adult hypertensive patients; Multicenter study in Ethiopia

Background Hypertensive patients are at high risk of adverse drug interaction (ADR) and drug-drug interaction (DDI) because of high tendency to use multiple drugs; this can undermine the quality of patients’ care. The aim of the study was to assess the magnitude of ADR, DDI, and their determinants among adult hypertensive patients at selected hospitals in Ethiopia. Methods A hospital-based cross-sectional study was conducted using chart reviews and patient interviews. DDIs were identified and classified using the Medscape online DDI checker. Written informed consent was obtained, and multivariate logistic regression was performed with statistical significance at p ≤ 0.05. Results Among a total of 543 hypertensive patients ADR was reported in 32.2%, with the most common being weakness (33.7%), followed by gastric irritation (33.1%), and headache (30.3%). Nearly half of the patients (47.9%) experienced at least one DDI. A total of 789 DDIs with mean of 3.03 ± 2.22 was identified in the study participants. Enalapril plus metformin was found as the most common contributing for DDI. Multivariable logistic regression analysis showed that patients with comorbid conditions, (AOR = 2.42; 95%CI: 1.25–4.67; p = 0.008), increasing number of concurrent medications use (AOR = 6.93; 95%CI: 4.50–10.69; p < 0.001), use of furosemide (AOR = 14.42; 95%CI: 4.38–47.48; p < 0.001), metformin (AOR = 23.57; 95%CI: 7.53–73.72; p < 0.001), and propranolol (AOR = 7.56; 95%CI: 1.12–50.61; p = 0.037) were significantly associated with higher odds of DDI. Increasing age (AOR = 1.017; 95%CI: 1.000–1.034; p = 0.044) and presence of comorbid conditions (AOR = 1.506; 95%CI: 1.001–2.264; p = 0.049) as well as, the use of enalapril (AOR = 1.751; 95%CI: 1.143–2.683; p = 0.010), nifedipine (AOR = 2.359; 95%CI: 1.013–5.492; p = 0.047), hydrochlorothiazide (AOR = 1.712; 95%CI: 1.112–2.635; p = 0.015) and increased number of concurrent medications (AOR = 1.287; 95%CI: 1.091–1.519; p = 0.003) were significantly associated with higher odds of ADRs. Conclusion This study found a high prevalence of DDI and ADR; with nearly half experiencing DDIs and about one-third reporting ADRs with different independent predictors. These findings highlight the need for regular medication review and close clinical monitoring to improve medication safety and optimize hypertension management.