TAK-536 (generic name: azilsartan) is an angiotensin II type 1 receptor blocker, discovered by Takeda and its mechanism of action is to lower blood pressure by inhibiting action of a vasopressor hormone Angiotensin II. Angiotensin II type 1 receptor antagonists have become an important drug class in the treatment of hypertension and heart failure. TAK-536 is in phase III clinical trial for treatment hypertension. This drug also known as active metabolite of the prodrug azilsartan medoxomil (also known as azilsartan kamedoxomil), but in some countries azilsartan rather than its prodrug is used for oral treatment.

Candesartan is classified as an angiotensin II receptor type 1 antagonist. Candesartan is an orally active lipophilic drug and possesses rapid oral absorption. It causes a reduction in blood pressure and is used in the treatment of hypertension. It is also used in the treatment of congestive heart failure and given as prophylaxis to reduce the severity and duration of migraine. Candesartan cilexetil, a prodrug of Candesartan, is available in the market under the trade names Atacand, Amias. Candesartan cilexetil is rapidly converted to candesartan, its active metabolite, during absorption from the gastrointestinal tract. Candesartan confers blood pressure lowering effects by antagonizing the hypertensive effects of angiotensin II via the RAAS (renin–angiotensin–aldosterone system). RAAS is a homeostatic mechanism for regulating hemodynamics, water, and electrolyte balance. During sympathetic stimulation or when renal blood pressure or blood flow is reduced, renin is released from granular cells of the juxtaglomerular apparatus in the kidneys. Renin cleaves circulating angiotensinogen to angiotensin I, which is cleaved by angiotensin converting enzyme (ACE) to angiotensin II. Angiotensin II increases blood pressure by increasing total peripheral resistance, increasing sodium and water reabsorption in the kidneys via aldosterone secretion, and altering the cardiovascular structure. Angiotensin II binds to two receptors: type-1 angiotensin II receptor (AT1) and type-2 angiotensin II receptor (AT2). Candesartan selectively blocks the binding of angiotensin II to AT1 in many tissues including vascular smooth muscle and the adrenal glands. This inhibits the AT1-mediated vasoconstrictive and aldosterone-secreting effects of angiotensin II and results in an overall decrease in blood pressure. Candesartan is greater than 10,000 times more selective for AT1 than AT2.

Losartan is a selective, competitive angiotensin II receptor type 1 (AT1) antagonist. Losartant is recommended as one of several preferred agents for the initial management of hypertension. Administration of losartan reduces the risk of stroke in patients with hypertension and left ventricular hypertrophy. Losartan is indicated for the treatment of diabetic nephropathy with an elevated serum creatinine and proteinuria in patients with type 2 diabetes and a history of hypertension.

Amlodipine is a dihydropyridine calcium antagonist (calcium ion antagonist or slow-channel blocker) that inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle. Experimental data suggest that amlodipine binds to both dihydropyridine and nondihydropyridine binding sites. The contractile processes of cardiac muscle and vascular smooth muscle are dependent upon the movement of extracellular calcium ions into these cells through specific ion channels. Amlodipine inhibits calcium ion influx across cell membranes selectively, with a greater effect on vascular mooth muscle cells than on cardiac muscle cells. Amlodipine is indicated for the treatment of hypertension and coronary artery disease.

Propagermanium, a newly introduced hydrophilic polymer of 3-oxygermanium propionic acid (3,3’-(1,3- dioxo-1,3-digermoxanediyl) bispropionic acid) has been reported to have antiinflammatory, antiviral and antineoplastic properties. In Japan propagermanium is approved for the treatment of HBe positive chronic hepatitis B. A postmarketing survey, however, revealed the occurrence of moderate to severe liver damage after the treatment in about 4% of patients. In most countries propagermanium falls under the regulations of dietary supplements. An import alert on germanium products was imposed by the U.S. FDA in 1988, because of possible injury to health. In Germany governmental institutions warned consumers of possibly fatal kidney damage.