Irbesartan/Amlodipine in Hypertensive Patients Uncontrolled on Irbesartan 150 mg Monotherapy

Primary Objective: To demonstrate that the antihypertensive efficacy of the fixed combination irbesartan/amlodipine 300/5 mg is superior to that of irbesartan 300 mg monotherapy in lowering systolic blood pressure (SBP) as measured by home blood pressure measurement (HBPM) after 10 weeks of treatment (W10) Secondary Objective: * To compare the antihypertensive efficacy of the fixed combination irbesartan/amlodipine 300/5 mg with that of irbesartan 300 mg monotherapy after 10 weeks of treatment (W10) * To compare the antihypertensive efficacy of the fixed combination therapy irbesartan/amlodipine 150/5 mg with that of irbesartan 150 mg monotherapy after 5 weeks of treatment (W5) * To examine in each treatment group the change from week 5 to week 10 in SBP and diastolic blood pressure (DBP) assessed by HBPM and by office blood pressure measurement (OBPM) * To determine the incidence and severity of adverse events