Influence of metoprolol on hemodynamics and respiratory function in asthmatic patients.

Studies of metoprolol in asthmatic patients showed beta 1-selective blocking properties on the adrenergic receptor. Metoprolol in a dose of 40 mg given orally to 9 asthmatic patients significantly decreased the pulse rate at 60 and 120 minutes and the systolic blood pressure at 120 minutes but did not cause any increase of respiratory impedance, measured by the forced oscillation technique. A double-blind test was carried out to compare the effects of metoprolol and inactive placebo on the respiratory response to isoproterenol in 24 asthmatic patients. In the metoprolol group, systolic blood pressure decreased significantly and pulse rate at rest also tended to decrease. There was no significant difference between the metoprolol and placebo groups in the respiratory response to an isoproterenol aerosol.