• A randomized, parallel, controlled study was conducted to evaluate the safety and efficacy of isradipine, 2.5 to 10 mg orally twice a day, compared with propranolol hydrochloride, 60 to 240 mg orally twice a day, in 78 hypertensives whose supine diastolic blood pressure was greater than 95 mm Hg while receiving 50 mg/d or more of hydrochlorothiazide. Isradipine or propranolol was titrated during a 10-week double-blind phase to achieve a supine diastolic blood pressure below 90 mm Hg while a fixed dose of hydrochlorothiazide was maintained. Supine diastolic blood pressure was reduced by 10 mm Hg in 88% of the isradipine/hydrochlorothiazide-treated and 83% of the propranolol/hydrochlorothiazide-treated groups and to less than 90 mm Hg in 55% of the isradipine/hydrochlorothiazide-treated and 69% of the propranolol/hydrochlorothiazide-treated patients. There was no significant difference in supine blood pressure reduction between either group, but there was a 3- to 4–beats per minute increase in supine heart rate in isradipine-treated patients and an expected 15- to 20–beats per minute decrease in heart rate in propranolol-treated patients. Five of 7 patients in the isradipine-treated group and 8 of 9 patients in the propranolol-treated group discontinued the therapy because of adverse reactions or treatment failure. Using Fisher's Exact Test, we found no significant difference in the relative frequency of individual adverse reactions between groups, although the absolute adverse reaction frequency was significantly higher with isradipine. This study demonstrates the effectiveness and safety of supplemental isradipine in the treatment of hypertension not controlled by hydrochlorothiazide alone.
(Arch Intern Med. 1989;149:2453-2457)