Effects of Combination Therapy With Alpha-1 Blocker (Bunazosin or Doxazosin) in the Treatment of Patients With Mild to Moderate Essential Hypertension

Subjects with mild to moderate essential hypertension, with the following criteria:

1. Washout period (Week -2)

   • Male or female subjects aged 20 to 80 years
   • Systolic blood pressure (SBP):140 mm Hg but \<180 mm Hg and/or diastolic blood pressure (DBP):90 mm Hg but \<110 mm Hg
   • Subjects who have given written informed consent prior to participation in the trial and who undertake to comply with the protocol

2. Angiotensin II antagonist mono-therapy period (week 0)

   • Subjects with systolic blood pressure >= 140 mm Hg but \<180 mm Hg and/or diastolic blood pressure >= 90 mm Hg but \<110 mm Hg
   • Presence of any 2 of the following 4 risk factors
   • Waist circumference: male > 90 cm, female > 80 cm
   • Triglycerides >= 150 mg/dl
   • HDL cholesterol: male \< 40 mg/dl, female \< 50 mg/dl
   • Fasting glucose >= 110 mg/dl

3. Angiotensin II antagonist with add-on Bunazosin or Doxazosin treatment period (Week 5)

   • SBP >=140 mm Hg or decrease \< 10 % OR
   • DBP >=90 mm Hg or decrease \< 10 % comparing the blood pressure at the entry of the Angiotensin II antagonist mono-therapy period.

Exclusion Criteria:

Subjects with the following conditions are not eligible for participation：

a) Washout period (Week -1 or -2)

• Subjects with severe hypertension (SBP>=180 mm Hg or DBP>=110 mm Hg).
• Subjects who have proven or suspected hypersensitivity to quinazoline derivatives
• Subjects who have a history of alcohol or drug abuse.
• Subjects with past or present evidence of cancer
• Subjects who have a past history of arterial fibrillation, heart failure (LVEF\<40%), acute coronary syndrome, myocardial infarction, stroke or severe arrhythmia.
• Subjects who are severely obese (BMI>30 kg/m2)
• Women who are pregnant or lactating or suspected of being pregnant.
• Subjects who have previously participated in any clinical trial of new or unapproved substances within the 12 weeks before starting of washout period
• Subjects on other anti-hypertensive or lipid-lowering medication
• Inability to return for scheduled visits or comply with any other aspect of the Protocol
• Subjects with poorly controlled diabetes mellitus (HbA1c > 10%)
• Subjects with concurrent serious hepatic or renal disorders (defined as AST and/or ALT > 3 times upper normal limit or Cr > 2mg/dl).
• Subjects who, in the opinion of the investigators, are poor medical candidates or pose any other risk for therapy with an investigational drug.