Hemodynamic Profile of the Cardiotonic Agent Pimobendan

Abstract

Pimobendan (UD-CG 115 BS) is a potent positive inotropic agent with vasodilatory properties. This hemodynamic profile was demonstrated in conscious rabbits chronically instrumented with Doppler flow probes. Pimobendan (10, 30, 100, and 300 micrograms/kg i.v.) increased cardiac output, stroke volume, heart rate, and mesenteric, renal, and hindquarter blood flow velocities, and decreased diastolic blood pressure. The positive inotropic effects of pimobendan and its effects on pre- and afterload were also shown in dogs with propranolol-induced depressed myocardial function. Pimobendan exhibited strong effects on stroke volume (up to 59%) and pulmonary capillary wedge pressure (up to -84%). The substance increased left ventricular (LV) dp/dtmax up to 150% and also had favorable effects on renal blood flow. Left ventricular function curves showed the usefulness of pimobendan in this acute heart failure model. Pimobendan is well absorbed and its duration of action is long. Positive inotropic effects of pimobendan were observed for 8-12 h after oral administration of 0.1-1 mg/kg to conscious dogs. It is concluded that pimobendan produces cardiovascular effects that may be useful in the treatment of congestive heart failure.