PIMOBENDAN - A REVIEW OF ITS PHARMACOLOGY AND THERAPEUTIC POTENTIAL IN CONGESTIVE-HEART-FAILURE

Pimobendan is a novel cardiotonic vasodilator (inodilator) which deriv es its inotropic activity from a combination of phosphodiesterase III inhibition and sensitisation of myocardial contractile proteins to cal cium. The acute haemodynamic benefits of pimobendan (2.5 to 10mg orall y; 5 to 10mg intravenously) seen in patients maintained on conventiona l diuretic, digitalis and vasodilator therapy for chronic heart failur e (increases in cardiac output nod stroke volume, and reductions in le ft ventricular preload and afterload) persisted on short term (1 month ) therapy, and showed only limited evidence of attenuation on longer t erm (6 months) oral therapy with pimobendan 2.5 or 5mg twice daily. Ad junctive therapy on with pimobendan 1.25 to 5mg twice daily for period s of 3 to 6 months improved exercise tolerance on symptom-limited exer cise testing, New York Heart Association (NYHA) functional class, and quality of life, and additionally reduced the need for hospitalisation in patients with moderate to severe chronic heart failure. Pimobendan appears to be well tolerated at therapeutic doses (1.25 to 5mg twice daily) in patients with chronic heart failure, and preliminary indicat ions suggest that it is largely devoid of the proarrhythmic effects of classical phosphodiesterase III inhibitors. Although information rega rding the long term effects of pimobendan on mortality is currently la cking, the drug nevertheless shows potential benefit as an adjunctive therapy in patients with chronic heart failure.