• Change From Baseline in Mean Trough Clinic Sitting Systolic Blood Pressure. [ Time Frame: Baseline and Week 24. ] [ Designated as safety issue: No ]
  The change in mean trough clinic sitting systolic blood pressure measured at final visit or week 24 relative to baseline. Systolic blood pressure is the arithmetic mean of the 3 trough sitting systolic blood pressure measurements.
  
  

• Change From Baseline in Mean Trough Clinic Sitting Diastolic Blood Pressure [ Time Frame: Baseline and Week 24. ] [ Designated as safety issue: No ]
  The change in mean trough clinic sitting diastolic blood pressure measured at final visit or week 24 relative to baseline. Diastolic blood pressure is the arithmetic mean of the 3 trough sitting diastolic blood pressure measurements.
  
  
• Change From Baseline in 24-hour Mean Systolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring. [ Time Frame: Baseline and Week 24. ] [ Designated as safety issue: No ]
  The change in 24-hour mean systolic blood pressure measured at week 24 relative to baseline. Ambulatory blood pressure monitoring measures blood pressure at regular intervals throughout the day and night. The 24-hour mean is the average of all measurements recorded for 24 hours after dosing.
  
  
• Change From Baseline in 24-hour Mean Diastolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring. [ Time Frame: Baseline and Week 24. ] [ Designated as safety issue: No ]
  The change in 24-hour mean diastolic blood pressure measured at week 24 relative to baseline. Ambulatory blood pressure monitoring measures blood pressure at regular intervals throughout the day and night. The 24-hour mean is the average of all measurements recorded for 24 hours after dosing.
  
  
• Change From Baseline in the 12-hour Mean Systolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring [ Time Frame: Baseline and Week 24. ] [ Designated as safety issue: No ]
  The change in the 12-hour mean systolic blood pressure measured at week 24 relative to baseline. Ambulatory blood pressure monitoring measures blood pressure at regular intervals throughout the day and night. The 12-hour mean is the average of all measurements recorded in the first 12 hours after dosing.
  
  
• Change From Baseline in the 12-hour Mean Diastolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring [ Time Frame: Baseline and Week 24. ] [ Designated as safety issue: No ]
  The change in the 12-hour mean diastolic blood pressure measured at week 8 relative to baseline. Ambulatory blood pressure monitoring measures blood pressure at regular intervals throughout the day and night. The 12-hour mean is the average of all measurements recorded in the first 12 hours after dosing.
  
  
• Change From Baseline in Daytime (6am to 10 pm) Mean Systolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring. [ Time Frame: Baseline and Week 24. ] [ Designated as safety issue: No ]
  The change in daytime (6am to 10pm) mean systolic blood pressure measured at week 24 relative to baseline. Ambulatory blood pressure monitoring measures blood pressure at regular intervals throughout the day and night. Daytime mean is the average of all measurements recorded between the hours of 6 am and 10 pm.
  
  
• Change From Baseline in Daytime (6am to 10 pm) Mean Diastolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring. [ Time Frame: Baseline and Week 24. ] [ Designated as safety issue: No ]
  The change in daytime (6am to 10pm) mean diastolic blood pressure measured at week 8 relative to baseline. Ambulatory blood pressure monitoring measures blood pressure at regular intervals throughout the day and night. Daytime mean is the average of all measurements recorded between the hours of 6 am and 10 pm.
  
  
• Change From Baseline in the Nighttime (12 am to 6 am) Mean Systolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring. [ Time Frame: Baseline and Week 24. ] [ Designated as safety issue: No ]
  The change in nighttime (12am to 6am) mean systolic blood pressure measured at week 24 relative to baseline. Ambulatory blood pressure monitoring measures blood pressure at regular intervals throughout the day and night. Nighttime mean is the average of all measurements recorded between the hours of 12 am and 6 am.
  
  
• Change From Baseline in the Nighttime (12 am to 6 am) Mean Diastolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring. [ Time Frame: Baseline and Week 24. ] [ Designated as safety issue: No ]
  The change in nighttime (12am to 6am) mean diastolic blood pressure measured at week 24 relative to baseline. Ambulatory blood pressure monitoring measures blood pressure at regular intervals throughout the day and night. Nighttime mean is the average of all measurements recorded between the hours of 12 am and 6 am.
  
  
• Change From Baseline in the Trough (22-24-hr) Mean Systolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring. [ Time Frame: Baseline and Week 24. ] [ Designated as safety issue: No ]
  The change in trough mean systolic blood pressure measured at week 24 relative to baseline. Ambulatory blood pressure monitoring measures blood pressure at regular intervals throughout the day and night. The trough mean is the average of all measurements recorded from 22 to 24 hours after dosing.
  
  
• Change From Baseline in the Trough (22-24-hr) Mean Diastolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring. [ Time Frame: Baseline and Week 24. ] [ Designated as safety issue: No ]
  The change in trough mean diastolic blood pressure measured at week 24 relative to baseline. Ambulatory blood pressure monitoring measures blood pressure at regular intervals throughout the day and night. The trough mean is the average of all measurements recorded from 22 to 24 hours after dosing.
  
  

A major component of blood pressure regulation is the renin-angiotensin-aldosterone system, a system of hormone-mediated feedback interactions that results in the relaxation or constriction of blood vessels in response to various stimuli. Angiotensin II, a polypeptide hormone, is formed from angiotensin I in a reaction catalyzed by angiotensin-converting enzyme as part of the renin-angiotensin-aldosterone system. Angiotensin II is the principal pressor agent of the renin-angiotensin-aldosterone system with a myriad of effects on the cardiovascular system and on electrolyte homeostasis. Two receptors for angiotensin II have been identified. Angiotensin II type 1 receptors are located predominantly in vascular smooth muscle, where activation by angiotensin II results in vasoconstriction, hypertrophic proliferation, and inflammation. In contrast, stimulation of angiotensin II type 2 receptors by angiotensin II results in vasodilatation, antiproliferative effects that are opposite from those of angiotensin II type 1 receptor stimulation.

Drugs that modulate the renin-angiotensin-aldosterone system are used commonly worldwide for the treatment of hypertension. Of these, some block the synthesis of angiotensin II by inhibiting angiotensin-converting enzymes, while others inhibit the action of angiotensin II by binding directly to the angiotensin II type 1 receptor (called angiotensin II receptor blockers), thereby causing vasodilatation of blood vessels, resulting in a reduction in blood pressure. The effects of angiotensin II receptor blockers on other conditions in which the renin-angiotensin-aldosterone system plays a significant role, such as congestive heart failure, postmyocardial infarction management and diabetic nephropathy have also been investigated.

Although antihypertensive agents are effective at the appropriate dose, the majority have side effects that limit their use. Angiotensin-converting enzyme inhibitors are commonly associated with cough and more rarely with angioedema. Beta-blockers are associated with fatigue and erectile dysfunction, calcium antagonists with peripheral edema and diuretics with metabolic complications. As a class, angiotensin II receptor blockers generally are considered more tolerable than other classes of hypertensive agents, although there is still a need for compounds with improved tolerability and efficacy for the treatment of hypertension.

TAK-491 (azilsartan medoxomil) is an angiotensin II receptor blocker with high affinity for, and selective antagonistic activity at, the angiotensin II type 1 receptor, and is being developed for clinical use as an antihypertensive agent.

Ramipril is an angiotensin-converting enzyme inhibitor widely prescribed in Europe and Asia for the treatment of mild to moderate essential hypertension.

This study is designed to compare the efficacy and safety/tolerability of azilsartan medoxomil and ramipril for the treatment of hypertension.

Participants in this study will be seen twice during the first month, then once a month for five months. Participants will also be required to fast for 8 hours prior to each visit to the study center. Total duration of study participation is 24-weeks, plus a safety follow up phone call after the study has ended.