CT-1 Mechanistic Evaluation of the Effects of Ranolazine on Ventricular Repolarization Luiz Belardinelli, MD VP, Drug Research and Pharmacological Sciences CV Therapeutics, Inc.

CT-2 QT Prolongation Alone Does Not Predict Torsade de Pointes (TdP) Increase in QTc Interval, msec Incidence of TdP, % A better surrogate of pro-arrhythmic potential is needed. Canine chronic AV node block model—Vos MA, et al. Circulation. 1998;98: Almokalant d-SotalolDofetilide Amiodarone

CT-3 Repolarizing current Action Potential Duration (APD) Early afterdepolarizations ↑ Dispersion of repolarization Torsade de Pointes SubstrateTrigger Drug-Induced Torsade de Pointes— Relationship to EADs and Dispersion   2 Long QT 3 4 (EADs) 1 I Kr Long QT EADs ↑ DISPERSION Torsade de Pointes

CT-4 3 EADs  Ectopic Beats Extrasystoles Initiating beats for torsade EADs  APD (  QT) EADs AP Ectopic beats ECG  Inward current (eg. I Na, I Ca )

CT-5 I Kr blocker † †d-Sotalol (I Kr blockers) 100 µM. LV wall Epicardium Mid-myocardium Endocardium LV chamber Transmural Differences of Ventricular Repolarization—A Mechanism for Arrhythmias Normal 4 APD, msec Arrhythmias enabled Shimizu et al. JCE. 1999;10: Dispersion 59

CT-6 The Effects of Ranolazine On: Ion currents Ventricular AP (and QT) EADs Dispersion of ventricular repolarization Models Single myocytes Cardiac tissue Isolated hearts Anesthetized dogs Humans Conditions (risk factors) Bradycardia (pauses) Electrolytes (  K o,  Mg o ) Gender (female) “Ion channel mutations” With Isoproterenol Disease (eg, CHF, ischemia)

CT-7 Ion current Effect on action potential Effect on ECG Ranolazine potency IC 50 I Kr inhibitionLengthens  QT 12 µM Late I Na inhibitionShortens  QT ≥ 5 µM Average therapeutic concentration range 850 to 2500 ng/mL (~2 to 6 µM) Late I Na effect mitigates I Kr effect Ion Current Effects—I Kr and Late I Na 1

CT-8 Ranolazine Prolongs APD and QT Interval but This Effect Is Not Heart Rate Dependent 2 ↑APD 90, msec Pacing rate, b/min Ranolazine (5 µM) E-4031 (1 µM) Slope = Slope = †Okada et al. J Am Coll Cardiol. 1996;27: MARISA (CVT 3031). A. Isolated hearts E-4031DofetilideRanolazine Change with drug,  slope QT vs heart rate B. Humans † Dofetilide-like I Kr blocker

CT-9 EADs Ectopic beats torsade  Ranolazine Does Not Induce Early Afterdepolarizations (EADs) 3 XXX †With 3 nM ATX. 1. I Kr blockers (d-sotalol, E-4031) - LQT2 2. I Ks blocker (chromanol 293B † ) - LQT1 3. Late I Na enhancer (anemone toxin, ATX-II) - LQT3 Ranolazine reverses APD (and QT) prolongation, suppresses EADs and ventricular tachycardia (VT) caused by

CT-10 Ranolazine suppresses EADs induced by: quinidine, anenome toxin (ATX II), E-4031 Suppression by Ranolazine of d-Sotalol- Induced EAD in Purkinje Fiber Preparation Control d-Sotalol 50 µM EAD Ranolazine 5 µM Ranolazine 10 µM

CT-11 Ranolazine Suppresses Ectopic Beats, EADs, and VT Induced by I Kr Block in Female Rabbit Hearts B. Ranolazine (30 µM) Multi-channel Blocker A. Control 3-sec pause CT-11

CT-12 Ranolazine Suppresses Ectopic Beats, EADs, and VT Induced by I Kr Block in Female Rabbit Hearts C. E-4031 (60 nM) I Kr Blocker A. Control 3-sec pause CT-12

CT-13 d-Sotalol, 100 µM ATX-II, 20 nM Ranolazine ATX-II d-Sotalol Canine LV wedge. BCL = 2000 msec. Ranolazine Does Not Increase Transmural Dispersion of Repolarization (TDR) NS TDR, msec 4 mM [K] o Ranolazine, µM

CT-14 EADs and Increased Dispersion of Ventricular Repolarization Predicts the Occurrence of TdP in Humans Drug evaluated Drug action in canine LV myocardium TdP reported in humans Induces EADs Increases TDR Quinidine (≤ 5 µM) +++ d-Sotalol +++ Terfenadine +++ Erythromycin +++ Cisapride +++ Sodium pentobarbital ––– Ranolazine –– ↓I Kr → ↑APD and QT

CT-15 Summary  Drugs that cause torsade de pointes –Prolong APD/QT –Induce EADs –Augment the dispersion of repolarization present in the normal heart  Ranolazine, 1 to 100 µM, prolongs APD & QT, but –Does not induce EADs –Does not increase dispersion of ventricular repolarization –Suppresses the arrhythmic effects of a number of QT-prolonging drugs –Would not be expected to cause torsade de pointes