The dog's role in the preclinical assessment of QT interval prolongation

During the development of a new therapeutic, few pharmacodyamic outcomes currently receive as much scrutiny as the effect of a potential medication on the electrocardiographic QT interval. The recent withdrawal from marketing of several drugs due to potential drug-related cardiac arrhythmias have greatly increased concern about drug-related changes on the QT interval. In order to reduce the incidence of these idiosyncratic episodes, regulatory agencies have suggested that sponsors use more rigorous methodology during the safety evaluation of new pharmaceuticals. Along with enhanced electrocardiographic assessments during clinical trials, advanced preclinical examinations of effect on QT interval and ventricular repolarization have become de rigueur. In this arena, the beagle dog is the preclinical species often associated with the most reliable predictivity for human safety assessment. To this end, canine models of cardiovascular safety assessment are discussed along with the relevance of these assays to human electrocardiography.