Respiratory effects of four adrenergic blocking agents combined with a diuretic in treating hypertension with concurrent chronic obstructive lung disease.

The study was a comparison of the effects on respiratory function produced by four antihypertensive agents with receptor-blocking properties (atenolol, oxprenolol, labetalol, metoprolol), when used in combination with a diuretic (chlorthalidone) in four homogeneous groups of hypertensive patients also suffering from chronic obstructive lung disease. All the agents with the exception of labetalol caused systematic and considerable worsening of functional parameters monitored in the trial. Treatment with labetalol, on the other hand, led to an improvement in respiratory function. Labetalol thus proved to be the most reliable and selective of the drugs tested for administration to patients with severe chronic airflow limitation.