Cadralazine versus prazosin as second-step treatment in hypertensive patients on beta-blockers: a randomized...

A randomized multicentre between-patient study comparison has been made of the efficacy and tolerability of cadralazine and prazosin, both administered for 6 weeks to hypertensive patients with a supine diastolic blood pressure (DBP) greater than or equal to 95 mmHg whilst on a beta-adrenoceptor-blocker. The doses of the beta-adrenoceptor-blocker (metoprolol SR 200 mg once daily) and cadralazine (10 mg once daily) were held constant during the study, while prazosin was individually titrated from 0.5 mg to a maximum of 2 mg tds. 108 patients (50 m and 58 f; mean age 54 y) were enrolled in 12 centres. Twelve patients withdrew due to adverse effects or poor efficacy (5 patients on prazosin and 7 on cadralazine). Both treatments induced a similar significant reduction in systolic blood pressure (SBP) and DBP, allowing normalization of BP in 58% of subjects on cadralazine and 55% on prazosin. Heart Rate (hR) increased significantly from 67 to 72 beats.min-1 in those on cadralazine and from 65 to 69 beats.min-1 on prazosin. Body weight was unchanged. Adverse effects were mild and typical of vasodilators, such as headache, flushing and dizziness. Physician evaluation of drug efficacy was not different between drugs, and cadralazine was rated better in terms of tolerability. Thus, in this multicentre study, cadralazine in the fixed dose of 10 mg once daily, as a second-step antihypertensive treatment in patients not satisfactorily controlled by a beta-adrenoceptor-blocker, was as effective and showed a similar side effect profile to prazosin given three times daily.