Electrophysiological Effects of Potential QT Prolonging Drugs

Since 2005, FDA has required almost all new drugs be tested for their ability to prolong the QT interval through clinical studies. This requirement stems from the increased TdP risk QT interval prolongation can cause. However, the QT interval is an imperfect biomarker, as there are multiple drugs that can prolong the QT interval, without causing increased TdP occurrence. As such, numerous drugs labeled as causing QT prolongation, may in fact have no impact on TdP occurrence. To address this problem, FDA, in collaboration with multiple external partners, has led an initiative to combine novel preclinical in vitro experiments within silico modeling and simulation followed by pharmacodynamic electrocardiographic (ECG) biomarkers. The goal is to use these novel computational and analytical tools to better predict TdP risk (beyond just the QT interval) by focusing on understanding the underlying mechanisms and applying an integrated biological systems approach. This clinical study consists of 2 parts: a 3-arm, 22-subject crossover study (Part 1) and a 4-arm, 22-subject crossover study (Part 2). These parts are included in the same protocol and study due to the similarity of the inclusion and exclusion criteria, similar procedures, and similar primary goals.