Quinolone use and QT interval prolongation: Risk assessment and the possible role of clinical pharmacist

Quinolones have long been utilized for treatment of microbial diseases and their advers effects are well known. One of these advers effects is the prolongation of QT interval which may advance to torsades de pointes, a fatal arrhythmia. In addition to several drugs, non-drug factors (female sex, congenital heart disease, electrolyte imbalance, etc.) may increase the risk for QT interval prolongation. One needs to take all risk factors into consideration when evaluating drug-induced prolongation of QT interval. In this study, an algorithm has been developed using the Tisdale Risk Score by a PhD student in clinical pharmacy to be used in minimizing the risk of QT interval prolongation in patients who will receive quinolone therapy at the Department of Infectious Diseases and Clinical Microbiology in Ankara University. Within the scope of this algorithm, electrocardiogram (ECG) and electrolyte follow-up plans were created for all patients participated in this study. A total of 32 patients were included. Thirteen patients were female and 19 were male. Based on the initial assesment, one patient was at high-risk, 14 patients at middle-risk and 17 patients were at low-risk groups. The algorithm necessitated daily ECG monitoring for 11 patients. The most used quinolone was found to be levofloxacin. The QTc interval values in follow-up ECGs were positively correlated with the risk scores (p<0,05). A negative correlation was observed between the risk scores and potassium values (p<0,05). We believe that this study raised an awareness the risk of QT interval prolongation that may occur during quinolone therapy. Additionally, various interventions suggested by the pharmacist contributed to improving patient outcomes. Therefore, it is considered that the pharmacist may have an active role in the risk prediction and management of drug-induced QT interval prolongation.