Prenalterol, an oral beta-1 adrenoceptor agonist, in the treatment of chronic heart failure.

The haemodynamic effects of prenalterol, a new beta-1 agonist, were studied in 10 patients with chronic heart failure. Following intravenous prenalterol infusions of 1 mg, 2.5 mg and 5 mg at 15 min intervals, oral slow release prenalterol 20 mg, 30 mg and 50 mg was given at 2 h intervals and then 50-100 mg bid for one month. There were no significant changes in heart rate or blood pressure. Cardiac output increased significantly from control of 4.4 +/- 0.91/min to a maximum of 5.8 +/- 1.81/min (p less than 0.01) following the 5 mg prenalterol infusion and this increase was maintained following oral prenalterol on Days 1 and 2 and at 1 month. Significant increases in stroke volume and stroke work indices and reduction in systemic vascular resistance were also observed. Maximum increases in cardiac output and stroke work index following intravenous prenalterol correlated significantly with maximum increases observed following oral prenalterol on Day 2. Non-invasive evaluation showed no change in echocardiographic left ventricular end-diastolic dimension but a significant reduction in left ventricular end-systolic dimension on Day 30. PEP/LVET was significantly reduced from control of 0.56 +/- 0.15 to 0.47 +/- 0.12 (p less than 0.05) on Day 2 and 0.49 +/- 0.09 (p less than 0.05) at 1 month. Treadmill exercise duration was significantly improved for the group at 1 month and no adverse effects were noted. Oral slow release prenalterol is a potentially useful new drug for patients with chronic heart failure.