Background Residents in long-term care facilities take many medications concomitantly, including antibacterials, which increases the risk of drug-drug interactions. Objectives The aims of the study were to investigate the prevalence of severe potential interactions between antibacterials and other medications in Slovenian long-term care facilities and to compare the performance of two different drug-drug interaction checkers in these settings. Setting Residents in long-term care facilities in Slovenia. Method A point-prevalence study was conducted from April 2016 to June 2016. Residents' characteristics, antibacterial treatment, and concomitant medications were obtained from their medical charts. Potential drug-drug interactions were determined using Lexicomp Online™ 3.0.2 and the online Drugs.com Drug Interactions Checker. The study only included potential drug-drug interactions categorized as type MA (major interactions) by the Drugs.com checker and as type X (should be avoided) by Lexicomp Online™. The study calculated the differences in the number of type X and MA potential drug-drug interactions between different antibacterial classes and between the two drug-drug interactions checkers. Main outcome measure Number of medications per patient, number of potential drug-drug interactions with antibacterial, and differences between two drug-drug interactions checkers. Results Eighty (68.4%) of Slovenian general long-term care facilities with 13,032 residents responded to the invitation. 317 (2.4%) of the residents received antibacterial treatment and 212 residents were included in the analysis. On average, they received 10.9 medications (SD = 3.9). Antibacterials were involved in 24.1% type MA potential drug-drug interactions and 26.4% type X potential drug-drug interactions. A significant difference in the total number of potential drug-drug interaction between the two checkers was found for all antibacterials, co-trimoxazole and fluoroquinolones (p < 0.005). Type X and MA potential drug-drug interactions were more common with fluoroquinolones than with beta-lactams or co-trimoxazole (p < 0.005). Conclusion Potential interactions between antibacterials, especially fluoroquinolones and other drugs, were common in long-term care facility residents treated with antibacterials. Differences in the number of potential drug-drug interactions between the two checkers indicate that if available the use of several sources of information is recommended in clinical practice. The results call for a collaborative approach to address the risks of drug-drug interactions.
Keywords: Antibacterials; Drug–drug interactions; Elderly; Interactions checkers; Long-term care; Slovenia.