The Combination of Chlorthalidone with Nifedipine Does Not Exert an Additive Antihypertensive Effect in Essential Hypertensives: A Crossover Multicenter Study

To evaluate whether the combination of nifedipine with chlorthalidone exerts an additive antihyperthensive effect when compared to single-drug treatment, 66 uncomplicated essential hypertensives, whose diastolic blood pressure was >100 and <115 mm Hg at the end of a 1-month washout placebo period, received, according to a randomized, double-blind, crossover design, nifedipine (20 mg b.i.), chlorthalidone (25 mg o.d.), the two drugs combined at the same doses, and the corresponding placebo.