Evaluation of ibopamine plus prazosin in congestive heart failure

To determine the acute haemodynamic response of a single dose co-administration of ibopamine plus prazosin in patients with congestive heart failure.

A double-blind, placebo-controlled randomised crossover study followed by a 2-week, open safety evaluation.

Wentworth Hospital, Durban.

12 patients with congestive heart failure who were in functional class (NYHA) II-III.

All patients underwent right heart catheterisation. On days 1 and 2 they received study drug or placebo plus prazosin and underwent haemodynamic recordings for 4 hours.

Single-dose (200 mg) ibopamine plus prazosin augmented cardiac output (and index) and an early (0-60 minute) phasic response in the pulmonary capillary wedge pressure (PCWP) that did not appear to be influenced by the presence of prazosin. The increase in cardiac output was accompanied by a moderate decline in systemic vascular resistance (P = NS) without a change in heart rate. In the open evaluation, 8/14 patients reported adverse events. Six events were considered to be related to study medication of which one (dizziness) occurred in the haemodynamic phase.

This study shows that ibopamine has beneficial haemodynamic effects in patients with moderate to severe heart failure. The increase in cardiac output was mild and sustained but with little change in systemic vascular resistance. The early rise in PCWP is not mediated by the alpha-agonistic vasoconstrictor effects of ibopamine.