[Comparative pharmacoclinical study of 2 beta-blockers: atenolol and betaxolol in slight-to-moderate arterial hypertension]

Abstract

Sixteen patients with mild to moderate hypertension were randomized to receive either atenolol 100 mg a day (group A: 2 females, 6 males, mean age 42.3 years) or betaxolol 20 mg a day (group B: 8 males, mean age 49.3 years), both drugs given once daily for one month with a wash out on the 5th day. Pretreatment blood pressure was significantly higher in group B than in group A: this disparity, linked with randomization, hampered the comparison of the antihypertensive efficacy of both drugs but not the comparison of their pharmacodynamics. The maximal effect on resting supine blood pressure occurred later with betaxolol (4th day) than with atenolol (1st day), while the effect on peak exercise-blood pressure and heart rate was rapidly maximal (1st day) for both beta-blockers. The duration of the antihypertensive action at rest seemed to be nearly similar, while the effects of betaxolol on exercising heart rate and blood pressure were more prolonged than those of atenolol: on the wash out day, plasma atenolol and betaxolol levels fell in a same way but the increase in peak systolic blood pressure was more marked in group A than in group B, so that the positive correlation we found between the plasma drug levels and the percentage of peak systolic blood pressure reduction, was much closer with atenolol (p less than 0.001) than with betaxolol (p less than 0.05).