Population Pharmacokinetic-Pharmacodynamic Analysis to Compare the Effect of Moxifloxacin on QT Interval Prolongation Between Healthy Korean and Japanese Subjects

PurposeThe goal of this study was to evaluate the moxifloxacin-induced QT interval prolongation in healthy male and female Korean and Japanese volunteers to investigate interethnic differences.MethodsThis multicenter, randomized, double-blind, placebo-controlled, 2-way crossover study was conducted in healthy male and female Korean and Japanese volunteers. In each period, a single dose of moxifloxacin or placebo 400 mg was administered orally under fasting conditions. Triplicate 12-lead ECGs were recorded at defined time points before, up to 24 hours after dosing, and at corresponding time points during baseline. Serial blood sampling was conducted for pharmacokinetic analysis of moxifloxacin. The pharmacokinetic-pharmacodynamic data between the 2 ethnic groups were compared by using a typical analysis based on the intersection-union test and a nonlinear mixed effects method.FindingsA total of 39 healthy subjects (Korean, male: 10, female: 10; Japanese, male: 10, female: 9) were included in the analysis. The concentration-effect analysis revealed that there was no change in slope (and confirmed that the difference was caused by a change in the pharmacokinetic model of moxifloxacin). A 2-compartment model with first-order absorption provided the best description of moxifloxacin's pharmacokinetic parameters. Weight and sex were selected as significant covariates for central volume of distribution and intercompartmental clearance, respectively. An Emax model (E[C]=[Emax⋅C]/[EC50+C]) described the QT interval data of this study well. However, ethnicity was not found to be a significant factor in a pharmacokinetic-pharmacodynamic link model.ImplicationsThe drug-induced QTc prolongations evaluated using moxifloxacin as the probe did not seem to be significantly different between these Korean and Japanese subjects. ClinicalTrials.gov identifier: NCT01876316.