Efficacy of Combination Antihypertensive Therapy with Low-Dose Indapamide: Assessment by Blood Pressure Self-Monitoring at Home

Abstract

We examined the effects of the addition of low-dose indapamide to antihypertensive drugs of other classes, as well as its duration of action, using blood pressure (BP) self-monitoring at home. Seventy-six patients undergoing monotherapy with a calcium channel blocker (CCB), angiotensin converting-enzyme inhibitor (ACEI), or angiotensin AT1-receptor blocker (ARB), but had an average morning home systolic BP (SBP) > or =135 mmHg or diastolic BP (DBP) > or =85 mmHg, were studied. Indapamide (1 mg) was added to their existing treatment once daily for 4 weeks. The additional hypotensive effects of indapamide were evaluated by casual and home BPs, and the results were compared among the three groups of subjects classified according to their initial drug treatment classes. The morning/evening (M/E) ratio of BP reduction was calculated to assess the duration of the effect. Overall, indapamide significantly (P < 0.001) lowered morning home BP (147 +/- 12/87 +/- 9 mmHg to 135 +/- 12/81 +/- 9 mmHg), evening home BP (138 +/- 15/79 +/- 10 mmHg to 126 +/- 12/73 +/- 9 mmHg), and casual BP (145 +/- 21/86 +/- 14 mmHg to 136 +/- 17/81 +/- 13 mmHg). All groups showed significant indapamide-induced home SBP/DBP decreases, whereas only the ACEI and ARB groups, but not the CCB group, showed a home pulse pressure (PP) reduction. Evening SBP and PP decreases were significantly greater in the ARB group than in the CCB group. The mean M/E ratio with indapamide was 0.95 for SBP and 0.85 for DBP. Low-dose indapamide used in combination can provide additional anti-hypertensive efficacy lasting for 24 h. The added effect of indapamide may be more prominent on ARBs than on CCBs.