Pimobendan (INN, or pimobendane; tradenames Vetmedin, Acardi, and Heartmedin) is a veterinary medication. Under the trade name Acardi, it is available for human use in Japan. Usually, this medicine is used to treat acute heart failure and chronic heart failure (mild to moderate in severity). By increasing the calcium ion sensitivity to protein regulating myocardial contraction and also by inhibiting phosphodiesterase (PDE-III) activity, this medicine dilates the blood vessels and improves the symptoms of heart failure such as shortness of breath and difficulty in breathing. Pimobendan is metabolized into an active metabolite (desmethylpimobendan) by the liver. The parent compound, pimobendan, is a potent calcium sensitizer while desmethylpimobendan is a more potent phosphodiesterase III inhibitor. Pimobendan is 90–95% bound to plasma proteins in circulation. This may have implications in patients suffering from low blood protein levels (hypoproteinemia/hypoalbuminemia) and in patients that are on concurrent therapies that are also highly protein bound.