Ventilatory effects of beta 1-receptor-selective blockade with bisoprolol and metoprolol in asthmatic patients

In a double blind, placebo-controlled study the ventilatory effects of the beta 1-selective receptor blockers bisoprolol (EMD 33512) and metoprolol and their interactions with the beta 2-adrenoceptor agonist terbutaline were investigated in 8 asthmatic patients. Both beta-blockers, in all the doses given, caused a significant decrease in peak expiratory flow rate (PEFR). Vital capacity (VC) and forced expiratory volume in one second (FEV1) were significantly decreased only after 10 mg bisoprolol. Terbutaline inhalation caused the same significant improvements in FEV1 and PEFR during placebo as during bisoprolol 10 mg, bisoprolol 20 mg and metoprolol 100 mg. Both beta-blockers caused equal changes in heart rate (HR) at rest. Systolic and diastolic blood pressure (BP) decreased significantly after bisoprolol 20 mg and metoprolol 100 mg, but not after bisoprolol 10 mg. Inhalation of terbutaline up to a dose of 3.5 mg had no influence on HR and BP. The results point to good beta 1-selectivity of bisoprolol 10 mg and 20 mg and metoprolol 100 mg in asthmatic patients. No correlation was found between the plasma levels of the beta-blockers and the changes in the ventilatory indices, HR or BP.