Irbesartan/Hydrochlorothiazide and Irbesartan in the Treatment of Mild to Moderate Hypertension

Study Objectives : * To demonstrate the reduction in office Blood Pressure following a 8-week regimen of irbesartan / hydrochlorothiazide using irbesartan as a reference. * To demonstrate the reduction in office Blood Pressure after 4-week regimen of irbesartan / hydrochlorothiazide using irbesartan as a reference. * To compare the response rate (defined as office Systolic Blood Pressure/Diastolic Blood Pressure reduce more than 10mmHg from Week 0) of patients after 4-week and 8-week regimen of irbesartan / hydrochlorothiazide versus irbesartan. * To compare the proportion of patients requiring titration after 4-week regimen of irbesartan/hydrochlorothiazide versus irbesartan * To ascertain the safety and tolerability of irbesartan / hydrochlorothiazide versus irbesartan when administered once daily