Double-blind comparison of tiapamil and atenolol in patients with mild to moderate hypertension: a multicenter trial

The efficacy and safety of tiapamil, a new calcium-channel blocker, was compared with the cardio-selective beta-blocker atenolol in a 16-week double-blind, multicenter trial with an initial 4-week placebo run-in period. Eighty-one outpatients with WHO stage I or II hypertension, 55 men and 26 women, entered the study. There was a total of nine drop-outs, six in the tiapamil group and three in the atenolol group. Five were due to side effects (four in the tiapamil group and one in the atenolol group). Sixty-one patients performed a graded exercise test sitting on a ergometer bicycle before and after completion of the therapy. Patients eligible for the study after the placebo period received either tiapamil 450 mg b.i.d. or atenolol 100 mg daily. Both drugs lowered systolic and diastolic blood pressure significantly. After 12 weeks of therapy, supine blood pressure in the tiapamil group fell from 167/104 mmHg to 154/91 mmHg (p less than 0.005), and in the atenolol group from 166/102 mmHg to 151/89 mmHg (p less than 0.005). A satisfactory reduction in diastolic blood pressure, defined as a reduction of more than 10 mmHg and/or values below or equal to 90 mmHg at the end of the study, was achieved in 29 of 35 patients in the tiapamil group and in 27 of 37 in the atenolol group. No changes in heart rate were observed in the tiapamil group, whereas there was a significant fall in heart rate in the atenolol group. The maximal exercise workload tolerated increased equally in both groups, from 135 to 147 watts.