Comparison of the antihypertensive activity of cadralazine (ISF 2469) and dihydralazine during chronic treatment.

The antihypertensive activity of a new vasodilating agent (ISF 2469) cadralazine (CD) was compared in a randomized, crossover, intrapatient study with that of hydralazine (HD) in 20 hypertensive patients whose diastolic blood pressure (BP) was greater than 95 mmHg during treatment with atenolol (AT), 100 mg 1 X daily. The initial dose of CD was 15 mg 1 X daily; after 15 days in case of poor response, the dose was increased to 20 mg 1 X daily. HD was given at a dose of 25 mg 3 X daily and was increased to 50 mg 2 X daily in case of poor response. BP values (standing) during AT were 174/108; they fell to 144/88 during CD and to 138/88 during HD. No significant difference was detected between the two drugs for both systolic and diastolic BP (supine and standing). Heart rate increased with both drugs, with a greater increase during CD. The difference was clinically nonsignificant. A total of 24 patients were enrolled, but 4 had to cease treatment because of side effects during HD. The overall prevalence of side effects was much higher during HD, especially during the first days of therapy. Also the severity of side effects was greater during HD. Our data show that CD has the same antihypertensive activity as HD with a lesser incidence of side effects and with a single dose/day administration in contrast with three administrations of HD. This can result in greater patient compliance.