Evaluation of potential and clinically significant drug interactions observed with psychotropic medications causing QT interval (QTc) prolongation in palliative care patients

This study aimed to describe the differences in the severity levels of potential drug-drug interactions (pDDIs) found by two drug interaction programs for psychotropic drugs and to find clinically relevant drug-drug interactions that cause QTc prolongation in patients receiving palliative care. A prospective study was conducted in the palliative care unit at the state hospital between October 2023 and May 2024. Micromedex® and Lexicomp® drug interaction programs were used to identify pDDIs and their severities. Electrocardiogram (ECG) was performed on patients who were observed to have a QTc prolongation risk warning in drug interaction programs. Additionally, the Drug Interaction Probability Scale (DIPS) criteria were utilized to identify clinically relevant drug interactions that result in QTc prolongation. 120 patients were included in this study. The interrater reliability was poor (kappa= −0.034) for major pDDI; in addition, the overall interrater reliability was only poor (kappa= −0.052). QTc prolongation was observed in 66.7% of the patients (n=38) who had an ECG performed (n=58). According to the DIPS evaluation, 122 clinically relevant DDIs (63 different pairs) were identified. The physician accepted only 4 (10.5%) out of 38 patients' recommendations from the clinical pharmacist. The patients underwent another ECG one week later, showing no signs of QTc prolongation. This study's results demonstrate that a considerable number of palliative care patients receive drug combinations that may result in drug interactions with psychotropic drugs, which are linked to a risk of QTc prolongation. Keywords: psychotropic drugs, clinical pharmacist, drug interactions, palliative care