| Abstrakt: |
Pirbuterol (PB), an oral beta-adrenergic-receptor agonist, has the pharmacologic effects of vasodilation and positive inotropy. The present studies were undertaken to determine the value of PB in the long-term therapy of chronic cardiac failure. A double-blind, randomized, 7-week trial comparing PB (20 mg three times daily) with placebo in 12 patients was followed by 12 weeks of open PB therapy. Dose-dependent nervousness and tremulousness limited the unit PB dose to less than 20 mg in six patients. In all patients, clinical status, exercise tolerance and maximal oxygen uptake, left ventricular echocardiographic dimension and cardiothoracic ratio were unchanged from control after 7 weeks of placebo or PB or after 12--19 weeks of PB. To assess the adequacy of 20 mg of PB, the dose-response relations of cardiocirculatory effects to 10, 15, 20 and 30 mg of PB were compared in seven of the above patients and nine other patients. Cardiac output was significantly elevated and wedge pressure reduced after all four doses, but these changes were sustained from 6 hours after 20- and 30-mg doses only. Thus, the role of PB in the management of chronic cardiac failure appears limited; judgment of its utility must await the results of additional controlled trials. |
