(-)-Pimobendan

(-)-Pimobedan is an isomer of pimobedan. It has the property of stereoselective partitioning or distribution into erythrocytes. The clearance of (-)-pimobedan from erythrocytes is significantly lower than that of (+)-pimobedan, which is entirely due to its stereoselective distribution into erythrocytes. This stereoselective property of (-)-pimobedan may explain the phenomenon previously reported that it produces a 1.5-fold greater contractile force than the (+)-isomer in detergent-treated myocardial specimens of guinea pigs and dogs. These properties suggest that (-)-pimobedan may have unique advantages in terms of in vivo distribution and pharmacological action, which may have important implications for its clinical use.