Regardless of your approach to thorough QT trials, key elements that must always be considered in study design include:

·         Parallel or crossover – Dependent on the half-life of the drug or population under evaluation, parallel or crossover study designs must be considered.

·         Number of subjects – Subject numbers can be determined by the variability of the QT measurement and the power needed, based on the estimated QT change. The number of groups participating can affect the variability of a study dramatically. One study split between several smaller groups and conducted at different sites may increase the variability of the QT measurement.

·         Timing of the baseline ECGs – These should be taken multiple times throughout the day before dosing and should correspond to the times of day that the ECGs are measured following dosing.

Regulatory agencies worldwide are increasingly requiring thorough QT studies as a component of marketing application submissions. Precise planning and proper execution can improve cost and time efficiencies of these studies.