The purpose of this study is to evaluate the effectiveness and safety of azilsartan medoxomil compared to placebo, once daily (QD), in African-American participants with essential hypertension.

Hypertension affects approximately 50 million individuals in the United States. As the population ages, the prevalence of hypertension will continue to increase if broad and effective preventive measures are not implemented. According to the World Health Organization, hypertension is the most common attributable cause of preventable death in developed nations, as uncontrolled hypertension greatly increases the risk of cardiovascular disease, cerebrovascular disease, and renal failure. Despite the availability of antihypertensive treatments, hypertension remains inadequately controlled; only about one third of patients continue to maintain control successfully.

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.

In the United States, a disproportionate number of African-Americans have hypertension compared to age-matched non-Hispanic Caucasians and Mexican Americans. Earlier onset and greater severity of hypertension in African-Americans contribute to greater target organ damage and may be a factor in shorter life expectancy in this population compared to Caucasian-Americans. Although genetic factors have been invoked to explain these racial differences, environmental factors probably play a more important role. Improved management of hypertension through both lifestyle intervention and pharmacotherapy, including combination therapy, are necessary to achieve target blood pressure in African Americans.

Takeda Global Research & Development Center, Inc. is developing TAK-491 (azilsartan medoxomil) to treat patients with essential hypertension. Azilsartan medoxomil is a prodrug that is hydrolyzed to the active moiety, TAK-536 (azilsartan), which is a selective antagonist of the angiotensin II type 1 receptor subtype.

This study is being conducted to evaluate the effectiveness and safety of oral azilsartan medoxomil compared with placebo in African-American participants with essential hypertension. Participation in this study is anticipated to be approximately 10 weeks.

Inclusion Criteria:

1. The participant has essential hypertension (defined as sitting trough clinic systolic blood pressure between 150 and 180 mm Hg, inclusive at Day -1) and 24-hour mean systolic blood pressure 130-170 mm Hg, inclusive, at Day 1.
2. Females of childbearing potential who are sexually active must agree to use adequate contraception, and can neither be pregnant nor lactating from Screening throughout the duration of the study.
3. Clinical laboratory evaluations within the reference range for the testing laboratory unless the results are deemed not clinically significant for inclusion into this study by the investigator.
4. Willing to discontinue current antihypertensive medication.

Exclusion Criteria:

1. Has sitting trough clinic diastolic blood pressure greater than 114 mm Hg.
2. Baseline 24 hour ambulatory blood pressure monitor reading of insufficient quality.
3. Hypersensitive to angiotensin II receptor blockers.
4. History of myocardial infarction, heart failure, unstable angina, coronary artery bypass graft, percutaneous coronary intervention, hypertensive encephalopathy, cerebrovascular accident, or transient ischemic attack.
5. Clinically significant cardiac conduction defects.
6. Hemodynamically significant left ventricular outflow obstruction due to aortic valvular disease.
7. Secondary hypertension of any etiology.
8. Non-compliant with study medication during run-in period.
9. Severe renal dysfunction or disease (based on calculated creatinine clearance less than 30 mL/min/1.73 m2) at Screening.
10. Known or suspected unilateral or bilateral renal artery stenosis.
11. History of drug abuse or a history of alcohol abuse within the past 2 years.
12. Previous history of cancer that has not been in remission for at least 5 years prior to the first dose of study drug.
13. Type 1 or poorly controlled type 2 diabetes mellitus.
14. Alanine aminotransferase level of greater than 2.5 times the upper limit of normal, active liver disease, or jaundice.
15. Hyperkalemia.
16. Upper arm circumference less than 24 cm or greater than 42 cm.
17. Works night (3rd) shift.
18. Currently is participating in another investigational study or has participated in an investigational study within 30 days prior to randomization.
19. Any other serious disease or condition at Screening (or Randomization) that would compromise participant safety, might affect life expectancy, or make it difficult to successfully manage and follow the participant according to the protocol.
20. Randomized in a previous azilsartan medoxomil study.
21. Is required to take or continues taking any disallowed medication, prescription medication, herbal treatment or over-the counter medication that may interfere with evaluation of the study medication.