The effect of bucindolol on the airway function of asthmatics

The airway and cardiovascular effects of separate single oral doses of 50, 100 and 200 mg of bucindolol were compared to those of placebo in a double-blind trial in 16 patients with mild to moderately severe asthma. Heart rate (HR), blood pressure (BP), forced vital capacity (FVC), forced expired volume in one second (FEV1), maximum expiratory flow at 50% of vital capacity (FEF50) and maximum expiratory flow at 75% of expired vital capacity (FEF75) were measured before and at intervals for 4h, when salbutamol (200 micrograms) was inhaled and the measurements repeated 15 min later. There was an interval of at least 4 days between each drug treatment day. Four of the 16 patients developed clinically significant bronchoconstriction with 50 mg (3) or 100 mg (1) of bucindolol and were withdrawn from the study. The remaining patients showed impaired bronchodilator response to salbutamol for each bucindolol dose as compared to placebo. No significant BP or HR effects were measured. Two patients withdrew because of circumstances unrelated to bucindolol induced bronchoconstriction. The development of bucindolol induced bronchoconstriction in this group of mild to moderate asthmatics was not predicted by the level of baseline pulmonary function, or the level of histamine responsiveness. However, there was a weak relationship between bucindolol induced bronchoconstriction and salbutamol induced bronchodilation. There are no definitive asthmatic characteristic to predict the likelihood of significant bucindolol induced bronchoconstriction in this asthmatic population.