Cadralazine, a new vasodilator, in addition to a beta-blocker for long-term treatment of hypertension.

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.