Dose-response relationship of the ?-adrenoceptor antagonist bisoprolol in patients with coronary heart disease and chronic obstructive bronchitis

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Abstract
The effects of single, consecutively increased, oral doses of the β-adrenoceptor antagonist bisoprolol (5, 10, 15, 20, 30 and 40 mg) on blood pressure, heart rate and bronchomotor tone were investigated in an open acute trial with 16 patients suffering from angina pectoris due to coronary heart disease and reversible chronic obstructive bronchitis. Even the lowest dose of bisoprolol (5 mg) caused a marked, long-lasting reduction in blood pressure and heart rate. After doses exceeding 20 mg, the incidence of an exaggerated pharmacodynamic effect on heart rate (β1-blockade) increased with dose. At doses above 30 mg, bisoprolol showed incipient impairment of bronchomotor function (β2-blockade) in individual patients. It is concluded that bisoprolol exhibits high β1-selectivity, i.e. a wide β1/β2 split, since blockade of bronchial β2-receptors only occurred at doses well above the therapeutically relevant dose range. The results may not be applicable to chronic treatment.