A thorough QT/QTc study in healthy white Caucasian subjects demonstrated that rupatadine has no proarrhythmic potential and raised no cardiac safety concerns. The present phase 1 study aimed to confirm the cardiac safety of rupatadine in healthy Japanese subjects. In this randomized, double-blind, placebo-controlled study, 27 healthy Japanese subjects were administered single and multiple escalating rupatadine doses of 10, 20, and 40 mg or placebo. Triplicate electrocardiogram (ECG) recordings were performed on days −1, 1, and 5 at several points, and time-matched pharmacokinetic samples were also collected. Concentration-effect analysis based on the change in the QT interval corrected using Fridericia's formula (QTcF) from average baseline was performed. Data from the formal TQT study in white Caucasian subjects was used for a comparison analysis. The ECG data for rupatadine at doses up to 40 mg did not show an effect on the QTc interval of regulatory concern. The sensitivity of this study to detect small changes in the QTc interval was confirmed by demonstrating a significant shortening of QTcF on days 1 and 5 four hours after a standardized meal. The data from this study exhibited no statistically significant differences in the QTc effect between Japanese and white Caucasian subjects. Keywords rupatadine, Japanese, cardiac safety, food effect, assay sensitivityThe International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guideline E14 recommends that the QTprolonging potential of a drug be evaluated primarily by a specific "thorough QT" (TQT) study. 1 In 2005, when the ICH was first adopted, it was not expected that the results of a TQT would be influenced by ethnic factors. However, emerging clinical experience has suggested that interethnic differences can be of particular relevance when assessing the safety of some drugs. 2 Since 2010, when the ICH E14 was fully adopted in Japan, the suitability of foreign data to provide proarrhythmic liability information concerning the Japanese population is still under assessment. Nevertheless, more efficient approaches to reduce the associated costs and alternatives to a conventional TQT study have been extensively discussed to modify the current regulatory requirements now allowing thorough QT assessments in other trials.