WEDNESDAY, Oct. 14 (HealthDay News) -- The addition of diuretics as a second-line approach to another anti-hypertensive agent further lowers systolic and diastolic blood pressure, providing the same effect as when used as first-line monotherapy, according to a review published online Oct. 7 in the Cochrane Database of Systematic Reviews.
Jenny M.H. Chen, M.D., of the University of British Columbia in Vancouver, Canada, and colleagues reviewed 53 trials in which 15,129 hypertensive patients with a mean baseline blood pressure of 156/101 mm Hg were randomly assigned to receive either a second-line thiazide diuretic or placebo. In 49 studies (92 percent), hydrochlorothiazide was used. They also reviewed three trials in which patients were randomly assigned to receive either a second-line loop diuretic or placebo.
The researchers found that second-line thiazide therapy at the manufacturer's recommended starting dose and two times the manufacturer's recommended starting dose was associated with blood pressure reductions of 6/3 mm Hg and 8/4 mm Hg, respectively. These reductions were similar to those seen with thiazide monotherapy. In addition, researchers found a starting dose of loop diuretics was associated with a blood pressure reduction of about 6/3 mm Hg.
"Thiazides when given as a second-line drug have a dose related effect to lower blood pressure that is similar to when they are added as a first-line drug. This means that the blood pressure lowering effect of thiazides is additive. Loop diuretics appear to have a similar blood pressure lowering effect as thiazides at one times the recommended starting dose," the authors conclude.