Effect of fixed-dose ACE-inhibitor/calcium channel blocker combination therapy vs. ACE-inhibitor monotherapy on arterial compliance in hypertensive patients with type 2 diabetes.

Assessment of vascular compliance may be a useful measurement of the clinical effects of antihypertensive treatment. Both angiotensin-converting enzyme (ACE) inhibitors and calcium channel blockers are known to improve vascular elasticity. A study was performed to test the hypothesis that combined therapy with an ACE inhibitor and a calcium channel blocker would have additive benefits on vascular compliance at similar levels of blood pressure (BP), as compared with monotherapy with an ACE inhibitor. This 12-week, double-blind study was a substudy of a larger clinical hypertension study conducted in patients with hypertension and type 2 diabetes. Subjects (N = 20) were randomized to either a fixed-dose combination of amlodipine besylate/benazepril HCl or to enalapril monotherapy. BP, heart rate, large- and small-vessel compliance, systemic vascular resistance, and urinary microalbumin excretion were assessed at baseline and after treatment. Both treatments were similarly effective in lowering BP, reducing systemic vascular resistance, and decreasing urinary microalbumin excretion. Improvement in large-vessel compliance was significantly greater among subjects who received ACE-inhibitor/calcium channel blocker combination therapy (52%) as compared with those who received ACE-inhibitor monotherapy (32%; p < 0.05). No significant change in small-vessel compliance was observed with either treatment. Greater improvement in large-vessel compliance with combination therapy was independent of BP lowering.