This study comprises a 3- to 6-week hydrochlorothiazide run in phase, followed by a 12 week double-blind treatment phase, followed by a 2 week single-blind follow-up hydrochlorothiazide treatment phase. The combined total duration of patient participation is approximately 17-20 weeks. Four double-blind treatment groups approximately equal in size (98) will comprise the study population: placebo or various alagebrium dose groups (10, 50, or 150 mg/day).

Inclusion Criteria:

• Men or women at least 45 years of age with uncontrolled systolic hypertension measured by office cuff and by an ambulatory blood pressure monitoring device
• Willingness to be taken off any current antihypertensive treatment to be placed on hydrochlorothiazide in combination with study medication.

Exclusion Criteria:

• Any significant history, systemic illnesses, or medical condition(s) that could lead to difficulty complying with the protocol or that could confound interpretation of the data.