Efficacy of ibopamine in the treatment of heart failure.

Loss of myocardial contractility, reflexly enhanced vasoconstriction, and neuroendocrine excitation are the pathophysiologic hallmarks of low-output heart failure. Drugs that counter both consequences afford considerable therapeutic potential in retarding and perhaps even in staying the consequences of the syndrome. Ibopamine possesses such potential through its unique ability to stimulate both dopaminergic- and beta-adrenoreceptors in the heart and circulatory system. Stimulation of dopaminergic- receptors and beta 2-adrenoreceptors results in vasodilatation in all regional vascular territories. beta 2-Adrenoreceptor agonist activity also affords mild positive inotropic activity in the heart, whereas stimulation of presynaptic dopaminergic- receptors (DA2) attenuates the increased sympathetic neural outflow. The drug also suppresses the renin-angiotensin-aldosterone system in addition to having a direct natriuretic activity. The pharmacodynamic effects of ibopamine, exerted through its metabolite epinine, are translated into measurable therapeutic benefits in patients with chronic heart failure. The increase in peripheral blood flow induced in all regional vascular territories, including the kidneys, is associated with increased cardiac output and stroke volume and reduction in left ventricular pressure work, wall stress, and myocardial oxygen consumption. Plasma norepinephrine, angiotensin, and aldosterone are also reduced, and renal sodium excretion is enhanced. These hemodynamic and neuroendocrine activities, which are not subject to tolerance during sustained administration of the drug, are accompanied by clinically significant improvement in symptoms, exercise tolerance, and the New York Heart Association classification of disability. More important, no proarrhythmic effects have been observed during sustained treatment, and the minimal side effects observed during long-term treatment enhance the safety profile of the drug.(ABSTRACT TRUNCATED AT 250 WORDS)