Influence of Different Bisoprolol Doses on Hemodynamics, Plasma Catecholamines, Platelet Aggregation, and α2- and β-Receptors in Hypertensive Patients

This study was designed to evaluate the effects of the beta 1-selective adrenoceptor antagonist bisoprolol on blood pressure, heart rate, plasma catecholamines, platelet aggregation, and alpha 2- and beta-adrenoceptor density in 45 male hypertensive patients (WHO stages I-II). Following a two-week placebo phase, the patients received either 5, 10, or 20 mg bisoprolol in a double-blind randomized fashion, once daily for 12 weeks. On days - 14, 0, 1, 7, 28, 56, 84, and 1 and 2 weeks after discontinuation of treatment (administration of placebo), blood pressure and heart rate were measured in the supine and sitting position, as well as during and after a 15-min exercise period on a bicycle ergometer. Simultaneously with the hemodynamic measurements, blood samples were obtained for the determination of plasma catecholamines. Blood samples for the assessment of beta-receptor density on lymphocytes and alpha 2-receptor density on thrombocytes, as well as thrombocyte aggregation sensitivity, were collected before bicycle ergometry. Five, 10, and 20 mg bisoprolol caused dose-dependent reductions of blood pressure and heart rate at rest and at peak exercise. The responder rates (diastolic BP less than or equal to 90 mm Hg) were 33%, 67%, and 100% with 5, 10, and 20 mg bisoprolol, respectively. After discontinuation of active treatment, blood pressure and heart rate gradually returned to pretreatment values within 1-2 weeks. Plasma epinephrine and norepinephrine levels in patients in the supine position remained unchanged during the whole course of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)