low affinity for muscarinic acetylcholine receptors and a high ED100(mydriasis)/ED50(antiarrhythmicactivity) ratio, was selected for further development and clinical evaluation as KW-3407. The synthesis and antiarrhythmicactivity of optically active 9 is described. The order of potency of antiarrhythmicactivity in ouabain-induced ventricular arrhythmias in dogs was (-)-9, (+/-)-9, and (+)-9.