Factorial Study of Metoprolol Succinate TOPROL-XL (324A)

A Phase III, Multi-Center, Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Factorial Study of Metoprolol Succinate Extended Release Tablets (TOPROL-XL) Hydrochlorothiazide and Their Combination in Patients With Essential Hypertension.

The purpose of this research study is to determine if treatment with the combination of metoprolol succinate and hydrochlorothiazide is more effective at lowering blood pressure than treatment with either of the two drugs alone. The study will also determine which combined doses of metoprolol succinate and hydrochlorothiazide are most effective at lowering blood pressure (without unacceptable side effects), and whether it is possible to combine both drugs in a single tablet to simplify blood pressure treatment.

Inclusion Criteria:

• Diastolic blood pressure between 95 and 114 mm at screening and start of treatment

Exclusion Criteria:

• Significant conditions which in the opinion of the investigator place the subject at undue risk, eg Renal impairment, hepatitis
• Known secondary causes of hypertension, eg, Cushing's syndrome, renal artery stenosis, pheochromocytoma, hyperaldosteronism
• Systolic blood pressure greater or equal to 180 mm Hg at start of trial