At equipotent doses, isradipine is better tolerated than amlodipine in patients with mild-to-moderate hypertension: a double-blind, randomized, parallel-group study.

1. The objective of this double-blind parallel-group study was to compare the tolerability of isradipine and amlodipine, specifically, the side-effects known to be related to the use of dihydropyridine calcium antagonists. 2. A total of 205 patients with mild-to-moderate essential hypertension were randomized to receive either the sustained-release (SRO) formulation of isradipine (n = 103) or amlodipine (n = 102), both at dosages of 5 mg once daily. Blood pressure measurements were taken at the end of the dosing interval to assess the antihypertensive efficacy of the two drugs. 3. Adverse reactions were assessed in two ways: a) spontaneously reported adverse events were recorded and investigated in depth for severity, duration, relation to the study drug, and outcome; b) a questionnaire was used to elicit specific adverse reactions known to be related to the use of dihydropyridine calcium antagonists which were evaluated for severity, duration, relation to the study drug, and outcome. 4. After 6 weeks of active treatment, both isradipine and amlodipine reduced mean sitting systolic/diastolic blood pressure: from 165.1/100.1 to 145.2/89.7 mm Hg with isradipine; and from 164.1/100.6 to 145.7/90.5 mm Hg with amlodipine. There was no difference in antihypertensive effect between isradipine and amlodipine (95% CI: -3.73 to 4.73 and -1.89 to 3.49 for differences in systolic and diastolic blood pressure, respectively). 5. The number of patients spontaneously reporting adverse events was significantly higher (P = 0.02; 95% CI: 3.1 to 26.7%) with amlodipine (33.3%) than with isradipine (18.4%).(ABSTRACT TRUNCATED AT 250 WORDS)