To Assess Allisartan Isoproxil/Amlodipine in Patients With Essential Hypertension Uncontrolled With Amlodipine or Allisartan Isoproxil

Inclusion Criteria:

• Patients 18-70 years old with mild to moderate essential hypertension;

• Untreated patients (either newly diagnosed essential hypertension or those patientswith a history of hypertension but have not been taking any antihypertensive drugsfor at least 2 weeks before the first visit) must have an office msSBP ≥ 150 mmHgand < 180 mmHg and DBP<110 mmHg;

• Patients who had not received regular treatment with Amlodipine Besylate (5 mg/day) (less than 4 weeks of medication intake or a history of missing doses for 5 or moredays within the 4 weeks before screening) with the mean sitting blood pressure of 140 mmHg≤ SBP <180 mmHg and DBP<110 mmHg;

• Patients currently receiving other antihypertensive agents (non-study medicationsfor at least 2 weeks prior to screening) with the mean sitting blood pressure of 140mmHg≤ SBP <180 mmHg and DBP<110 mmHg, and the clinician determined that it wasappropriate to switch to Amlodipine Besylate (5 mg/day);

• Patients who have been stably treated with Amlodipine Besylate (5 mg/day) for atleast 4 weeks with the mean sitting blood pressure of 140 mmHg≤ SBP <180 mmHg andDBP<110 mmHg. During randomization for the double-blind treatment period, meansitting blood pressure should be 140 mmHg≤ SBP <180 mmHg and DBP<110 mmHg;

• Participants enrolled in the ambulatory blood pressure monitoring (ABPM) studyshould have 24-hour mean ambulatory blood pressure ≥130/80 mmHg after 4 weeks ofmonotherapy treatment;

Exclusion Criteria:

• Patients with secondary hypertension;

• Patients with msSBP ≥180 mmHg and/or msDBP≥110 mmHg, or with hypertensive emergencyor hypertensive urgency.

• Patients with history of heart failure (New York Heart Association (NYHA) FunctionalClassification class III and IV), acute coronary syndrome, percutaneous coronaryintervention, or other serious heart diseases (such as cardiogenic shock, moderateor severe heart valvular disorders, atrioventricular block second or third degree,bradycardia (with a heart rate <50 beats per minute), severe arrhythmias) in thepast 6 months.

• Patients with history of severe cerebrovascular diseases (such as hypertensiveencephalopathy, cerebrovascular injury, stroke, transient ischemic attack) in thepast 6 months.

• Patients with aortic aneurysm, aortic dissection, or dissecting aneurysm.

• Patients with renal artery stenosis or severe renal insufficiency (Cr>1.5 times theupper limit of normal).

• Patients with blood potassium >5.5 mmol/L.