<abstract><sec>
<title>Objective</title>
<p>This study was aimed to evaluate polypharmacy and drug interactions in intensive care units.</p>
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<title>Materials and methods</title>
<p>This epidemiologic-descriptive study was performed on the records of 80 patients admitted to the intensive care unit with a duration of more than 48 hours from 2018-10-23 to 2019-01-21. The patients' records, including polypharmacy, type and number of drug interactions as well as factors such as age, gender, hospitalization duration, number of drug-prescribing physicians were investigated. To determine drug interactions, Free <italic>Lexi-Comp</italic> <italic>iOS</italic> software version 4.0.1 was used.</p>
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<title>Findings</title>
<p>Of 80 participants in this study, 58, and 22 patients (72.5%, and 27.5%) were respectively male and female, with a mean age of 39.9 years; besides, 46.2%, and 25.3% of patients were hospitalized due to trauma, and non-traumatic cerebral hemorrhage, respectively. The average hospitalization was six days. The average number of drug-prescribing physicians and medications received was 5 and 10, respectively. The majority of patients (91.2%) received over five drugs. The majority of drug interactions (70%) were in C-Class, and 1.2% were in X-Class. Also, 85% of the studied samples had at least one drug interaction.</p>
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<title>Conclusion</title>
<p>Polypharmacy and drug interactions were common in patients hospitalized in the intensive care unit ward. Risk factors for increasing drug interactions were the length of stay and number of medications prescribed, and for polypharmacy, length of stay, number of medications-prescribing physicians, and number of prescription medications.</p>
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