Two drugs are better than one for reducing moderate hypertension, a two-part multinational experiment shows.The parallel studies compared the effects of varying dosages of the calcium channel blocker amlodipine and and the angiotensin II receptor blocker (ARB) valsartan (Diovan)—separately and in tandem—with a placebo. Both studies lasted eight weeks and enrolled patients, mean age 55 years, with mild-to-moderate hypertension (diastolic BP [DBP] >95-<110 mm Hg). The first study included 1,911 patients in six countries, who received 2.5 mg or 5 mg of amlodipine and/or 40-320 mg of valsartan, or a placebo.

The second trial enrolled 1,250 patients in 10 countries and explored higher dosages. American patients were included in both trials.

In both studies, the combination therapy almost always resulted in a significantly greater decrease in BP than either medicine alone or the placebo. The sharpest declines were evident at the highest doses. When 320 mg valsartan was paired with 10 mg amlodipine, patients experienced an 18.6 mm Hg reduction in DBP and a 28.4 mm Hg drop in systolic BP (SBP). That compared with declines of 15.6 mm Hg in DBP and 24.1 mm Hg in SBP with 10 mg amlodipine alone and 13.3 mm Hg in DBP and 19.8 mm Hg in SBP with 320 mg of valsartan. In addition, the combination therapy caused fewer side effects than monotherapy. Peripheral edema occurred in 5.4% of patients who took both drugs, vs. 8.7% who took only amlodipine.

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Headache followed a similar pattern of 4.3% vs. 7.6%. “The combination therapy was generally well tolerated, even at high doses,” the researchers said (Clin Ther. 2007;29:563-580).