Background The treatment of heart failure patients is very complex and includes lifestyle modification as well as different pharmacological therapies. Polypharmacy is very common in such patients and they are at increased risk of potential drug-drug interactions and associated effects such as poor adherence, compliance and adverse events. Objective The aim of the present study is to investigate retrospectively the prescribed pharmacotherapy of the hospital discharged heart failure patients for possible drug interactions. Settings Clinic for Cardiology of the "Saint Marina" University Hospital in Varna, Bulgaria. Method Lexicomp® Drug interaction software was used for screening potential drug-drug interactions. Logistic regression was applied to determine the odds ratio for the association between the age and number of drugs taken and the number of potential drug-drug interactions. Main outcome measure Incidence and type of pDDIs in geriatric heart failure patients. Results A retrospective study was conducted by reviewing the medical records of 248 selected heart failure patients for the prescribed medicines for a 1-year period (January 2015-December 2015). The total number of potential drug-drug interactions was 1532, or approximately 6.28 (± 4.72 SD) per one person. The range of prescribed drugs was between three and fourteen, 92% of them have been taking more than five medicines, an average of 7.12 (± 2.07 SD) per patient. The average age was 72.35 (± 10.16 SD). The results have shown stronger association between the number of drugs taken (more than 7) and the occurrence of potential drug-drug interactions (more than 10)-37.84 (95% CI 9.012-158.896, P ≤ 0.001). No statistically significant differences were found between age and occurrence of potential drug-drug interactions (more than 10)-1.008 (95% CI 0.441-2.308, P = 0.848). Conclusion The incidence of drug-drug interactions in heart failure patients is high. The clinical pharmacist, as a part of the multidisciplinary team, could reduce medication-related problems, such as drug interactions, and to optimize drug therapy by checking the treatment prescribed at the discharge of these patients.
Keywords: Bulgaria; Clinical pharmacist; Drug–drug interactions; Heart failure; Polypharmacy.