QT interval prolongation caused by concomitant use of moxifloxacin hydrochloride injection and amiodarone hydrochloride for injection

Abstract

A 75-year-old male received an IV infusion of moxifloxacin hydrochloride injection (moxifloxacin) 400 mg/d once daily for valvular heart disease complicated with heart failure and pulmonary infection. On the second day, the electrocardiogram showed that the corrected QT interval (QTc) was prolonged from 455 ms before treatment to 490 ms. On the third day, amiodarone hydrochloride for injection (amiodarone) 150 mg was given by slow intravenous injection in the early morning due to atrial fibrillation and 300 mg of amiodarone was continuously pumped at the speed of 30 mg/h at noon. In the afternoon of the 4th day, amiodarone 300 mg was given again via a pump at a speed of 30 mg/h. About 20 minutes later,the QTc was prolonged to 607 ms. On the 5th day, amiodarone was not given again, but the QTc continued to be prolonged up to 674 ms. On the 6th day, the QTc gradually returned to be within the normal range after discontinuation of moxifloxacin. The prolongation of QT interval in the patient was considered to be associated with moxifloxacin and amiodarone. Key words: Moxifloxacin; Amiodarone; Long QT syndrome