Ability of Late Sodium or Calcium Current Block to Balance the ECG Effects of Potassium Current Block

Exclusion Criteria

• •1\. Subject has a 12 lead safety ECG result at Screening or Check in of Period 1 with evidence of any of the following abnormalities:
• •* QT corrected interval (QTc) using Fridericia correction (QTcF) \>430 milliseconds (ms)
• •* PR interval \>220 ms or \<120 ms
• •* QRS duration \>110 ms
• •* Second- or third-degree atrioventricular block
• •* Complete left or right bundle branch block or incomplete right bundle branch block
• •* Heart rate \<50 or \>90 beats per minute
• •* Pathological Q-waves (defined as Q wave \>40 ms)
• •* Ventricular pre-excitation
• •2\. Subject has more than 12 ectopic beats during the 3 hour Holter ECG at Screening.
• •3\. Subject has a history of unexplained syncope, structural heart disease, long QT syndrome, heart failure, myocardial infarction, angina, unexplained cardiac arrhythmia, torsades de pointes, ventricular tachycardia, or placement of a pacemaker or implantable defibrillator. Subjects will also be excluded if there is a family history of long QT syndrome (genetically proven or suggested by sudden death of a close relative due to cardiac causes at a young age) or Brugada syndrome.
• •4\. Subject has a history or current evidence of any clinically significant (as determined by the investigator) cardiovascular, dermatologic, endocrine, gastrointestinal, hematologic, hepatic, immunologic, metabolic, neurologic, psychiatric, pulmonary, renal, urologic, and/or other major disease or malignancy (excluding nonmelanoma skin cancer). The investigator may allow exceptions to these criteria (e.g., stable mild joint disease \[that will not interfere with or influence the activities required by the protocol, in the opinion of the investigator\], cholecystectomy, childhood asthma) following discussion with the medical monitor.
• •5\. Subject has a history of thoracic surgery.
• •6\. Subject has any condition possibly affecting study drug absorption (e.g., gastrectomy, Crohn's disease, irritable bowel syndrome).
• •7\. Subject has a skin condition likely to compromise ECG electrode placement.
• •8\. Subject is a female with breast implants.
• •9\. Subject's laboratory test results at Screening or Check in of Period 1 are outside the reference ranges provided by the clinical laboratory and considered clinically significant (as determined and documented by the investigator or designee).
• •10\. Subject's laboratory test results at Screening or Check in of Period 1 indicate hypokalemia, hypocalcemia, or hypomagnesemia according to lower limits of the reference ranges provided by the clinical laboratory.
• •11\. Subject's laboratory test results at Screening or Check in of Period 1 are \>2 × the upper limit of normal (ULN) for alanine aminotransferase or aspartate aminotransferase, \>1.5 × ULN for bilirubin, or \>1.5 × ULN for creatinine.
• •12\. Subject has a positive test result at Screening for human immunodeficiency virus, hepatitis C antibodies, or hepatitis B surface antigen.
• •13\. Subject has a mean systolic blood pressure \<90 or \>140 mmHg or a mean diastolic blood pressure \<50 or \>90 mmHg at either Screening or Check in of Period 1.