Low-Dose Triple Antihypertensive Combination Therapy in Patients with Hypertension: A Randomized, Double-Blind, Phase II Study

Purpose: We evaluated the dose-responsiveness, efficacy, and safety of low-dose triple antihypertensive combination therapies in patients with mild-to-moderate hypertension. Patients and Methods: After a 1 to 2-week placebo run-in period, 248 patients were randomized to the half-dose triple combination (amlodipine 2.5 mg + losartan 25 mg + chlorthalidone 6.25 mg), third-dose triple combination (amlodipine 1.67 mg + losartan 16.67 mg + chlorthalidone 4.17 mg), quarter-dose triple combination (amlodipine 1.25 mg + losartan 12.5 mg + chlorthalidone 3.13mg), amlodipine 10mg, amlodipine 5mg, losartan 100mg, and placebo groups for 8 weeks. The primary outcome was the mean change in systolic blood pressure (SBP) from baseline to week 8. Results: The placebo-corrected SBP reductions of the half-dose, third-dose, quarter-dose combination, amlodipine 10 mg, amlodipine 5 mg and losartan 100 mg treatments were -17.2, -19.5, -14.9, -18.5, -11.3 and -9.9 mmHg, respectively. The BP control and response rates were significantly higher in the half-dose, third-dose, and quarter-dose combination groups than in the placebo group (all p < 0.01). Despite no intergroup differences in study drug-related adverse events, ankle circumference increased significantly in the amlodipine group compared to those in the combination treatment groups. The quarter-dose combination, amlodipine 5 mg, and losartan 100 mg groups showed similar SBP reduction and BP response rates. The SBP reduction and BP response rate in the third-dose and half-dose combination groups were not significantly different from those in the amlodipine 10 mg group but superior to those in the losartan 100 mg group. Conclusion: Low-dose triple combination therapies could be effective as antihypertensive therapies.