51 hypertensive outpatients, whose diastolic blood pressure exceeded 100 mmHg after a 2-week period on
atenolol alone (100 mg once daily) participated in this long-term study. They received, in addition to
atenolol, the
vasodilator cadralazine (
ISF 2469; 10 to 30 mg once daily) for a standard period of 24 weeks, according to an open design.
Cadralazine caused a progressive and important decrease in both systolic and diastolic blood pressure, from 173/111 mmHg (end of
atenolol alone) to 154/99 mmHg (12th week, p less than 0.01/p less than 0.01; mean dose, 24.5 mg/day). At this time a
diuretic was added as a third-step
drug in 15/51 initial patients (29%), and final blood pressure in all patients was 150/96 mmHg (p less than 0.01/p less than 0.01), with positive results in 88% of the cases. During
cadralazine treatment, heart rate was always significantly lower than before
atenolol alone; the most common side effects, many of which were already present during treatment with
atenolol alone, included
headache,
asthenia,
dizziness, palpitation and
flushing, and tended to disappear spontaneously as
therapy progressed. Routine laboratory tests did not show important changes;
sodium excretion was not reduced. In conclusion, the therapeutic efficacy of
cadralazine, its low or absent
salt and water retention effects, its good tolerability, and the high compliance obtained with once daily administration allowed the use of this
vasodilator as a second-step
drug for long-term treatment of
hypertension.