Potential drug-drug interactions in ICU patients: a retrospective study.

Objectives A "potential drug-drug interaction" (pDDI) is the possibility one drug has to alter the effects of another when both are administered simultaneously. Intensive care unit (ICU) patients are especially prone to these pDDIs. This study aimed to determine the frequency and severity of pDDIs during the hospitalization of patients in the ICU. Methods This study was conducted retrospectively in three hospitals, including both governmental and non-governmental hospitals in Nablus, Palestine, over the course of six months; starting in January 2018 and ending in June 2018. The sample size included 232 ICU patients, and medications prescribed during the hospitalization of these patients were evaluated for pDDIs using the drugs.com application. Results A total of 167 patients (72%) were found to have at least one pDDI, while the total number of pDDIs in the study was 422, resulting in an average of 1.82 pDDIs per patient. Out of the total identified pDDIs, 41 interactions (9.7%) were major interactions, 281 (66.6%) were moderate interactions and 100 (23.7%) were minor interactions. The past medical history of these patients showed that many had hypertension (29%), diabetes mellitus (25%) and ischemic heart disease (10%). A serious combination, enoxaparin and aspirin, was found in six patients. Furthermore, as the number of administered drugs increased, the number of interactions increased as well. Conclusions The pDDIs are common in ICU patients. The most common and clinically most important pDDIs require special attention. Polypharmacy significantly increases the number and level of pDDIs, especially in patients with multiple chronic illnesses. Adequate knowledge regarding the most common pDDIs is necessary to enable healthcare professionals to implement ICU strategies that ensure patient safety.