Pimobendane (UD-CG 115 BS) in chronic congestive heart failure. Short-term and one-month effects of a new inotropic vasodilating agent.

We studied the effects of oral administration of pimobendane on hemodynamics, blood gas levels, the renin-angiotensin system, and plasma catecholamines in 11 patients who were affected by severe chronic congestive heart failure. Following the administration of 5 mg, the cardiac index increased from 2.0 +/- 0.2 to 2.5 +/- 0.2 L/min/m2 (p less than 0.01), and the pulmonary wedge pressure decreased from 28 +/- 3 to 17 +/- 4 mm Hg (p less than 0.01). The maximal changes were noted five hours after intake of the drug. In spite of a significant decrease in arterial oxygen pressure (PaO2) (from 81 +/- 4 to 67 +/- 5 mm Hg; p less than 0.05), a significant increase in the oxygen delivery index was seen (from 322 +/- 32 to 436 +/- 38 ml/min/m2; p less than 0.01). The patients who were submitted to long-term treatment (5 mg twice daily) and who were reassessed after at least one month exhibited an improved cardiac index from 1.9 +/- 0.2 to 2.5 +/- 0.1 L/min/m2 (p less than 0.01), as well as a decreased pulmonary wedge pressure from 26 +/- 2 to 14 +/- 4 mm Hg (p less than 0.01). The norepinephrine levels were significantly reduced after one month (from 1,496 +/- 185 to 678 +/- 95 pg/ml; p less than 0.01), whereas the plasma renin activity was not. One patient died suddenly during the one-month follow-up period. With the exception of one case, which was also treated with heparin, a transient cutaneous rash and a drop in the level of blood platelets were observed, pimobendane was well tolerated. This new inotropic and vasodilating drug thus seems to have promise for the treatment of chronic congestive heart failure.