Effects of dibutyryl cyclic AMP on patients with severe heart failure.

Dibutyryl cyclic AMP was administered to 2 patients with severe congestive heart failure. After an intravenous drip infusion of dibutyryl cyclic AMP (300 mg/40 min), marked diuresis and mild improvement of the patients' physical activity occurred. The cardiac index increased and both systemic vascular resistance and pulmonary capillary wedge pressure decreased. Blood glucose and plasma insulin increased simultaneously, while plasma free fatty acid decreased during the infusion. A continuous intravenous micro-infusion of dibutyryl cyclic AMP (300 mg/24 h) also exerted diuresis and improved physical activity. The hemodynamic and metabolic effects of dibutyryl cyclic AMP are expected to be beneficial to a failing heart.