The cardioselective and hypotensive effects of bisoprolol in hypertensive asthmatics

The cardioselectivity and hypotensive properties of the beta 1-specific beta-blocker bisoprolol were investigated using a single-dose comparison of 10 and 20 mg bisoprolol, 100 mg atenolol, and placebo in 12 hypertensive asthmatic patients. The study was of a randomised four-way crossover design with 1 week's washout between each treatment. beta 1-Selectivity was determined by using lung function parameters--vital capacity (VC), airway resistance (AWR), peak expiratory flow rate (PEFR), forced expiratory volume (FEV1)--at baseline and at predetermined intervals following each medication and salbutamol challenge. Potency of beta-blockade was determined using heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP). 100 mg atenolol and 10 and 20 mg bisoprolol reduced HR, SBP, and DBP 2 h postmedication. All active treatments produced only small nonsignificant reductions in PEFR, FEV1, and VC, compared with baseline, without any significant differences between the four groups. Bisoprolol at both dose levels had only a minor nonsignificant influence on AWR. 100 mg atenolol significantly increased AWR, compared with placebo. Following all treatments, salbutamol did not affect cardiovascular parameters, but significantly reduced AWR and increased PEFR, FEV1, and VC without any significant differences between groups. Bisoprolol, at both dose levels tested, was found to possess a strong beta 1-adrenoceptor-blocking activity without affecting bronchial beta 2-adrenoceptors. An equipotent beta 1-adrenoceptor-blocking dose of atenolol (100 mg), compared with 10 and 20 mg bisoprolol, was found to increase airway resistance in the population of asthmatic patients studied. Bisoprolol has been shown to exhibit a greater beta 1-selectivity than atenolol.