[Therapeutic benefit of a low dose of indapamide: results of a double-blind against placebo European controlled study]. / Bénéfice thérapeutique d'une faible dose d'indapamide: résultats d'une étude européenne contrôlée en double aveugle contre placebo.

Indapamide is a diuretic prescribed in the treatment of hypertension at the dosage of 2.5 mg per day. In accordance with international recommendations concerning the need to use low doses of antihypertensives, a new lower-dose form of indapamide has been developed to achieve the best safety/efficacy ratio by decreasing the incidence of hypokalemia. A new pharmaceutical sustained-release (SR) form was developed to give a smooth pharmacokinetic profile in comparison with the indapamide instant release (IR) form. The aim of this study was to determine the lowest new dosage of the SR form producing similar hypertensive efficacy as the LR form, and decreasing the percentage of patients with a serum potassium concentration below 3.4 mmol/l. This multicenter study was designed as a single-blind, run-in, placebo period of 1 month, followed by a double-blind, active treatment period of 2 months, using parallel groups: 285 patients with essential uncomplicated mild-to-moderate hypertension (95 mmHg < or = supine diastolic blood pressure (sDBP) < or = 114 mmHg) were included and randomly treated by either IR indapamide (2.5 mg) or SR indapamide (1.5, 2.0, 2.5 mg). After 2 months of active treatment, the one-way analysis of variance on the principal criterion (difference in sDBP between M2 and M0) revealed a significant treatment effect (p = 0.016). The mean drop in sDBP (+/- standard deviation) was 5.8 mmHg (+/- 8.6) after 2 months of placebo; 10.1 mmHg (+/- 7.0) after indapamide IR 2.5 mg; and 11.0 mmHg (+/- 9.4), 8.9 mmHg (+/- 9.4), and 10.5 mmHg (+/- 8.5) after indapamide SR 1.5 mg, 2 mg, and 2.5 mg, respectively. The difference between the placebo and indapamide treatment was significant (p < or = 0.05). No significant difference was detected between the various indapamide treatments, i.e., no difference between the IR and SR formulations, no difference between the various dosages of the SR form, and therefore no dose/effect relationship in the dose interval tested (SR 1.5, 2, and 2.5 mg). The incidence of patients with a serum potassium concentration less than 3.4 mmol/l was lower with indapamide SR 1.5 mg (11%) than with indapamide 2.5 mg, SR 2 mg, and SR 2.5 mg, respectively: 29%, 18% and 14%. These results show the interest of a low dose of indapamide in improving the safety while producing the same antihypertensive efficacy.