Oritavancin, a new lipoglycopeptide antibiotic: results from a thorough QT study

Oritavancin is a lipoglycopeptide with broad activity against gram-positive bacteria. To exclude an effect on cardiac repolarization, oritavancin was studied in a thorough QT study. In vitro assays have demonstrated a 10-fold safety margin between the concentration that resulted in 50% block of the cardiac potassium current and therapeutic plasma levels in patients and no safety margin for block of the sodium currents. In a parallel-group study, 240 male and female subjects received treatment with either the clinical dose (200 mg intravenously) or a supratherapeutic dose (800 mg intravenously) of oritavancin, placebo, or a positive control (400 mg of oral moxifloxacin). Electrocardiograms were recorded in triplicate at several time points after dosing. The primary end point was the largest baseline-adjusted, placebo-corrected QTcI observed at any point after oritavancin dosing. The study's sensitivity to demonstrate a sufficiently small QTc change was confirmed by the moxifloxacin effect. The baseline-adjusted, placebo-corrected QTcI was between -3 milliseconds and 3 milliseconds after 800 mg of oritavancin, and an effect exceeding 6 milliseconds was confidently excluded. Other electrocardiographic parameters were unaffected by the treatment. It was concluded that oritavancin did not cause QTc prolongation in this thorough QT study.