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 compa re the tolerability of isradipine and amlodipine, specifically, the si de-effects known to be related to the use of dihydropyridine calcium a ntagonists. 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 effi cacy of the two drugs. 3 Adverse reactions were assessed in two ways: a) spontaneously reported adverse events were recorded and investigate d in depth for severity, duration, relation to the study drug, and out come; 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 dr ug, 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%). 6 The incidence of spontaneously reported ankle oedema was statistically significantly greater with amlodipine than with isradipine (14.7% vs, 5.8%, respectively, P = 0.04). In addition, the severity (P = 0.02) a nd duration (P = 0.03) of the ankle oedema was greater with amlodipine than with isradipine. Moreover, eight patients taking amlodipine disc ontinued treatment due to this side-effect compared with none of the p atients taking isradipine. 7 By questionnaire, the severity (P = 0.03) and duration (P = 0.02) of nausea as well as the severity of ankle oe dema (P = 0.04) were greater with amlodipine than with isradipine. 8 I n conclusion, at equipotent antihypertensive doses, isradipine compare d with amlodipine treatment resulted in a statistically significantly lower incidence of spontaneously reported adverse events in general an d of ankle oedema in particular.