ABSTRACT
Introduction: Drug-drug interactions (DDI) are generally a significant cause of morbidity and mortality, as well as increased costs and length of hospital stay. In Sweden today, electronic health records with integrated DDI warnings have been implemented in virtually all hospitals, with the exception of the intensive care units, where the medications charts are either still on paper or, if electronic, still not connected to DDI warning systems. However, in the ICU, it may well be that the clinical relevance of interaction warnings differ from ordinary care, due to the type of medications used, as well as the close monitoring of the patients. Objectives: This study aimed to determine the frequency of potential DDIs and clinically relevant DDIs during the hospitalization of patients in three different Swedish ICUs at the same university hospital. Methods: This observational pilot study was conducted at a mixed ICU, a cardiothoracic ICU and a neurosurgical ICU over the course of a total of 5 months during the covid-19 pandemic year 2021. The investigator visited the ward once weekly and checked all prescribed medications on that day for each patient against the DDI database SFINX/Janusmed Interactions. The result was communicated to the physician in charge. Results: The sample size included 172 patients. A total of 53 patients (31%) were found to have at least one potential DDI (pDDI). The most common pDDIs in all three ICUs were drugs with risk of QT prolongation and drugs with increased risk of serotonergic toxicity. 29-41% of the pDDIs in the different ICUs were drugs with risk of QTprolongation, the most frequent drugs being amiodarone, antibiotics (erythromycin, moxifloxacin and ciprofloxacin) and ondansetrone. 7-24% of the pDDIs in the different ICUs were drugs with increased risk of serotonergic toxicity, the most frequent drugs being selective serotonin reuptake inhibitors (SSRI), fentanyl, remifentanil, pethidine and metoclopramide. Neurosurgical intensive care patients were exposed to higher frequency of pDDI with serotonergic toxicity compared with the other intensive care unit-patients. Observed pDDIs led to dose-adjustment in 6 cases and exchange of drugs in 4 cases. No adverse drug reactions (ADRs) were observed. Conclusion: Potential DDIs are common in ICU patients, but far from all are clinically relevant.We need to learn more about the clinical relevance of the pDDIs in this patient setting, as a basis for customized either manual or computerized decision support algorithms to decrease the risk of unfavorable outcomes due to DDIs.