This is a randomized, double-blind, crossover study to evaluate chlorthalidone and hydrochlorothiazide and their effects on endothelial function in hypertensive patients. Subjects will receive chlorthalidone 12.5 mg, hydrochlorothiazide 25 mg, and placebo each for 4 weeks with a 1 week washout between study periods. Sequence of study drugs will be randomized. Flow mediated vasodilatation will be measured at baseline and after each treatment period.
Chlorthalidone will result in improved endothelial function compared to hydrochlorothiazide as measured by flow mediated vasodilatation.