Objective: Flow-mediated dilation (FMD) and nitroglycerin-mediated dilation (NMD) in the brachial artery are well-known indices for evaluating endothelial function (ECF). The blood pressure-lowering effects of the combination of losartan (ARB) and low-dose hydrochlorothiazide (H: ARB-H; ARB, 50 mg and H, 12.5 mg) are useful. The aim of the present study was to examine whether the combination of losartan and low-dose hydrochlorothiazide could improve ECF.
Methods: To investigate the effect of ARB-H on ECF in patients with uncontrolled hypertension despite the use of amlodipine (2.5 mg daily), we performed a randomized controlled open-labeled study by using the envelope method and assigned 42 patients to either a control (CTRL) group or an ARB-H combination group, both of which received amlodipine 2.5 mg daily during the treatment period. In addition, both the CTRL (n=21, 69±7 years old) and ARB-H groups (n=21, 69±7 years old) received additional behavioral modification. Before and after 8 weeks of therapy, FMD and NMD were measured in both groups using novel FMD equipment (UNEXEF18G).
Results: Although baseline FMD was not different between the two groups, post-therapy FMD increased in the ARB-H group (2.97±1.56 to 3.95±1.86%, p<0.05) but did not change significantly in the CTRL group (2.95±1.43 to 3.11±1.27%, NS). No significant change was seen in NMD when comparing baseline and post-therapy values in either group. No treatment complications were observed.
Conclusion: A fixed-dose combination of losartan and hydrochlorothiazide enhances ECF, suggesting that this combination might have both anti-hypertensive and anti-atherosclerotic effects in patients with hypertension.