To explore the role of β1 -adrenoceptors (ARs) in the heart rate response to the selective β3 -adrenoceptor agonist mirabegron, 12 young male volunteers received single oral doses of the nonselective β1/2 -AR antagonist propranolol (160 mg), the selective β1 -AR antagonist bisoprolol (10 mg), or placebo on days 1 and 5 of each period in a 3-period crossover study. On day 5, dosing was followed by a supratherapeutic dose of mirabegron (200 mg). Vital signs, impedance cardiography, and plasma renin activity were collected. Mirabegron increased heart rate and systolic blood pressure and reduced stroke volume, whereas cardiac output and diastolic blood pressure were unaffected. Mirabegron-induced changes were attenuated by propranolol and bisoprolol. The data indicate that mirabegron has a positive chronotropic effect at supratherapeutic concentrations, which is at least partly mediated by stimulation of β1 -AR.
Keywords: cardiovascular; heart rate; impedance cardiography; mirabegron; β-adrenoceptor.
© 2017, The American College of Clinical Pharmacology.