Clinical trial NCT00696384
Conditions: Hypertension
Keywords: Essential Hypertension Cardiovascular Disease High Blood Pressure Drug Therapy
Sponsor: Takeda
Start date: 2007-06-01; Completion date: 2009-04-01
Enrollment: 418 participants; Allocation: RANDOMIZED; Intervention model: PARALLEL

Brief summary:
The purpose of this study is to determine the long term safety and tolerability of azilsartan medoxomil, once daily (QD), in participants with Essential Hypertension.

Detailed description:
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.

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. AII 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 (AT1) 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 (AT2) receptors by angiotensin II results in vasodilation, antiproliferative effects, and other effects that are opposite from those of AT1 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 enzyme inhibitors, while others inhibit the action of angiotensin II by binding directly to the AT1 receptor (angiotensin II receptor blockers), thereby allowing blood vessels to dilate, 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, post-myocardial infarction management, and diabetic nephropathy, also are being investigated.

Takeda Global Research \& Development Center, Inc. is developing TAK-491 (azilsartan medoxomil) to treat mild to moderate essential hypertension. Nonclinical studies have indicated that azilsartan medoxomil is an antagonist of the AT1 receptor subtype.

This study consists of 2 phases. The first phase will be a 26-week, open-label, multicenter phase to evaluate the safety and tolerability of TAK-491 in participants with essential hypertension. Investigators were instructed to manage participants according to a protocol-specified treatment algorithm to achieve target blood pressure. All participants who completed the open-label phase then were randomized into a 6-week double-blind, placebo-controlled (azilsartan medoxomil \[maintained at the final dose from the open-label phase\] or placebo, in addition to their current other antihypertensive medications including chlorthalidone, as applicable) reversal phase to evaluate maintenance/durability of azilsartan medoxomil -mediated blood pressure reduction, as well as potential rebound following the cessation of azilsartan medoxomil.

Study participation is anticipated to be about 8.5 Months. Multiple procedures will occur at each visit which may include fasting, blood collection, urine collection, vital signs including sitting and standing blood pressure and pulse, body height and weight, physical examinations and electrocardiograms.

Arms: arm 1: None arm 2: None arm 3: None
Interventions: intervention 1: Azilsartan medoxomil intervention 2: Azilsartan medoxomil, with or without chlorthalidone and other non-angiotensin II receptor blocker antihypertensive medications. intervention 3: Placebo
Intervention descriptions: intervention 1: All subjects initiated azilsartan medoxomil 40 mg, tablets, orally, once daily for four weeks, force-titrated to 80 mg, tablets, orally, once daily. After Week 8, chlorthalidone, 25 mg, tablets, orally, once daily as needed and other antihypertensive medications as needed to achieve target blood pressure (defined as \<140/90 mm Hg for participants without diabetes or chronic kidney disease (CKD) and \<130/80 mm Hg for participants with diabetes or CKD) for up to 26 weeks.

Study medication could have been up-titrated only after the subject had been at the previous dose level for a minimum of 2 weeks. Study medication could only have been up- or down-titrated by 1 dose level per scheduled or unscheduled visit. intervention 2: Azilsartan medoxomil at the final dose received during the open-label phase: (20 mg, 40 mg or 80 mg), tablets, orally, once daily with or without chlorthalidone 25 mg, tablets, orally once daily and other non-ARB antihypertensive medications (if currently taking), for 6 weeks/Week 32. intervention 3: Azilsartan medoxomil placebo-matching tablets, orally, once daily with or without chlorthalidone 25 mg or other non-ARB antihypertensive (if currently taking), tablets, orally, once daily for 6 weeks/Week 32.

Protocol documents: