Evaluation of the Cardiac Safety of Long-Acting Endectocide Moxidectin in a Randomized Concentration-QT Study

Potential effects on cardiac repolarization of single doses of moxidectin, a potent long-acting macrocyclic lactone endectocide, were assessed in a concentration-QT (c-QT; exposure-response) study. This double-blind, placebo-controlled, parallel-group study in healthy male volunteers (n = 60) randomized subjects to a single oral dose of moxidectin (4 mg, 8 mg, 16 mg, 24 mg, or 36 mg) or matching placebo. Serial plasma samples for pharmacokinetic (PK) analysis and concurrent triplicate electrocardiogram measurements were taken at baseline and 14 prespecified time points over 72 hours, yielding 900 QT interval-plasma concentration time-matched pairs. Moxidectin had no statistically significant or clinically relevant impact on QT interval at any dose level. The primary mixed effects model analysis revealed no treatment-related impact on the Fridericia-corrected QT interval-plasma concentration gradient (-0.0077, 90% confidence interval (CI) -0.0255 to +0.0101).