Design and synthesis of orally bioavailable Kv1.5 antagonists for the treatment of atrial fibrillation

MEDI 449

B. Wesley Trotter, bwesley_trotter@merck.com, Department of Medicinal Chemistry, Merck Research Laboratories, West Point, PA 19486
The development of ion channel blockers for the treatment of atrial fibrillation (AF) has attracted widespread interest in recent years. The prevalence of AF is rising as the population ages, and the disease has been identified as a major contributor to stroke and resultant morbidities and mortalities. Because current therapies can promote potentially lethal ventricular proarrhythmia, we have focused on antagonists of the Kv1.5 potassium channel and its associated current, IKur, which is observed in the human atrium but not in ventricle. We present here the synthesis and optimization of Kv1.5 antagonists guided by ion channel assay data, pharmacokinetic evaluation, and in vivo rat and dog cardiac electrophysiological experiments. Studies of key compounds have led to the identification of orally bioavailable antagonists that selectively increase atrial refractory period in a dog pharmacodynamic model.