An antiarrhythmic agent; a stereoisomer of quinine; blocks Nav1.5 in a use-dependent manner; decreases the amplitude and duration of action potentials in isolated canine ventricular myocytes; inhibits KKr, peak INa, and late INa (IC50s = 4.5, 11, and 12 μM) and can induce torsade de pointes in isolated rabbit hearts at 1 μM; induces QT prolongation in dogs; binds to M2 muscarinic acetylcholine receptors (Ki = 7.5 μM)