The hemodynamic effects of ibopamine (SB-7505), the orally active 3,4-diisobutyryl ester of N-methyldopamine, were studied in 12 patients with congestive heart failure (CHF) after acute dosing, after 20 days of maintenance therapy and after 20 days of drug discontinuation. Acute ibopamine administration increased at rest cardiac index (CI p less than 0.05) and stroke work index (SWI p less than 0.05), and reduced pulmonary capillary wedge pressure (PCWP), mean pulmonary arterial pressure (PAP), total systemic (SVR p less than 0.05) and pulmonary vascular resistance (PVR). These beneficial hemodynamic effects were maintained during supine bicycle exercise: CI and SWI increased more markedly (p less than 0.05) and PCWP increased at a lower extent (p less than 0.05) after ibopamine than on control conditions. PVR exhibited a more pronounced decrease (p less than 0.02), while SVR showed superimposable reductions before and after ibopamine. After chronic therapy with the drug, hemodynamics and left ventricular function again improved during exercise, while withdrawal of ibopamine resulted in hemodynamic deterioration. Heart rate and systemic arterial pressure did not change significantly after the drug. This study demonstrates that ibopamine is able to improve cardiac performance during exercise in CHF patients after both acute and chronic administration.