Ambrisentan (alternative Names: BSF 208075; GSK 1325760; GSK1325760A; Letairis) is an endothelin receptor antagonist that is selective for the endothelin type-A (ETA) receptor. The chemical name of ambrisentan is (+)-(2S)-2-[(4,6-dimethylpyrimidin-2-yl)oxy]-3-methoxy-3,3-diphenylpropanoic acid. Ambrisentan is indicated for the treatment of pulmonary arterial hypertension. It is approved in Europe, Canada and the United States for use as a single agent to improve exercise ability and delay clinical worsening. In addition, it is approved in the United States for use in combination with tadalafil to reduce the risks of disease progression, hospitalization and to improve exercise ability. As an endothelin receptor antagonist, ambrisentan prevents endogenous endothelin peptide from constricting the muscles in blood vessels, allowing them to relax and permit a reduction in blood pressure. Endothelin-1 (ET-1) is a potent autocrine and paracrine peptide. Two receptor subtypes, ETA and ETB, mediate the effects of ET-1 in the vascular smooth muscle and endothelium. The primary actions of ETA are vasoconstriction and cell proliferation, while the predominant actions of ETB are vasodilation, antiproliferation, and ET-1 clearance. In patients with PAH, plasma ET-1 concentrations are increased as much as 10-fold and correlate with increased mean right atrial pressure and disease severity. ET-1 and ET-1 mRNA concentrations are increased as much as 9-fold in the lung tissue of patients with PAH, primarily in the endothelium of pulmonary arteries. These findings suggest that ET-1 may play a critical role in the pathogenesis and progression of PAH. Ambrisentan is a high-affinity (Ki=0.011 nM) ETA receptor antagonist with a high selectivity for the ETA versus ETB receptor (>4000-fold). The clinical impact of high selectivity for ETA is not known.

Aliskiren – the only direct renin inhibitor which is clinically used as an antihypertensive drug. Aliskiren is the first of a new class of antihypertensive agents. Aliskiren is a new renin inhibitor of a novel structural class that has recently been shown to be efficacious in hypertensive patients after once-daily oral dosing. In short-term studies, it was effective in lowering blood pressure either alone or in combination with valsartan and hydrochlorothiazide, and had a low incidence of serious adverse effects. It was approved by the Food and Drug Administration in 2007 for the use as a monotherapy or in combination with other antihypertensives. Aliskiren is marketed under the trade name Tekturna. Aliskiren effectively reduces functional plasma renin activity by binding to renin with high affinity, preventing it from converting angiotensinogen to angiotensin I. The inhibition of renin by aliskiren is associated with a reduction in circulating levels of angiotensin I and II, with a resultant increase in plasma renin concentration and inhibit activation of mitogen-activated protein kinases ERK1 (p44) and ERK2 (p42).

Ranolazine is a metabolic modulator developed by Syntex (Roche) and sold under the trade name Ranexa by Gilead Sciences. Ranexa has antianginal and anti-ischemic effects that do not depend upon reductions in heart rate or blood pressure. The mechanism of action of ranolazine is unknown. It does not increase the rate-pressure product, a measure of myocardial work, at maximal exercise. In vitro studies suggest that ranolazine is a P-gp inhibitor. Ranolazine is believed to have its effects via altering the trans-cellular late sodium current. It is by altering the intracellular sodium level that ranolazine affects the sodium-dependent calcium channels during myocardial ischemia. Thus, ranolazine indirectly prevents the calcium overload that causes cardiac ischemia. Because Ranexa prolongs the QT interval, it should be reserved for patients who have not achieved an adequate response with other antianginal drugs. Ranexa should be used in combination with amlodipine, beta-blockers or nitrates. The effect on angina rate or exercise tolerance appeared to be smaller in women than men.

Treprostinil (marketed under the trade names Remodulin for infusion) is a vasodilator that is used for the treatment of pulmonary arterial hypertension. Pulmonary arterial hypertension (PAH) is a disease in which blood pressure is abnormally high in the arteries between the heart and lungs. PAH is characterized by symptoms of shortness of breath during physical exertion. The condition can ultimately lead to heart failure. Treprostinil is a potent oral antiplatelet agent. The major pharmacologic actions of treprostinil are direct vasodilation of pulmonary and systemic arterial vascular beds and inhibition of platelet aggregation. In animals, the vasodilatory effects reduce right and left ventricular afterload and increase cardiac output and stroke volume. Other studies have shown that treprostinil causes a dose-related negative inotropic and lusitropic effect. No major effects on cardiac conduction have been observed. Treprostinil had high affinity for the Prostaglandin D2 receptor (DP1), Prostaglandin E2 receptor EP2 subtype (EP2) and Prostaglandin D2 receptor (IP) receptors (Ki 4.4, 3.6 and 32 nM, respectively), low affinity for EP1 and EP4 receptors and even lower affinity for EP3, Prostaglandin F (FP) and thromboxane (TP) receptors. Treprostinil has demonstrated a unique effect on PPAR gamma, a transcription factor important in vascular pathogenesis as a mediator of proliferation, inflammation and apoptosis. Through a complementary, yet cyclic AMP-independent pathway, treprostinil activates PPARs, another mechanism that contributes to the anti-growth benefits of the prostacyclin class.

Treprostinil (marketed under the trade names Remodulin for infusion) is a vasodilator that is used for the treatment of pulmonary arterial hypertension. Pulmonary arterial hypertension (PAH) is a disease in which blood pressure is abnormally high in the arteries between the heart and lungs. PAH is characterized by symptoms of shortness of breath during physical exertion. The condition can ultimately lead to heart failure. Treprostinil is a potent oral antiplatelet agent. The major pharmacologic actions of treprostinil are direct vasodilation of pulmonary and systemic arterial vascular beds and inhibition of platelet aggregation. In animals, the vasodilatory effects reduce right and left ventricular afterload and increase cardiac output and stroke volume. Other studies have shown that treprostinil causes a dose-related negative inotropic and lusitropic effect. No major effects on cardiac conduction have been observed. Treprostinil had high affinity for the Prostaglandin D2 receptor (DP1), Prostaglandin E2 receptor EP2 subtype (EP2) and Prostaglandin D2 receptor (IP) receptors (Ki 4.4, 3.6 and 32 nM, respectively), low affinity for EP1 and EP4 receptors and even lower affinity for EP3, Prostaglandin F (FP) and thromboxane (TP) receptors. Treprostinil has demonstrated a unique effect on PPAR gamma, a transcription factor important in vascular pathogenesis as a mediator of proliferation, inflammation and apoptosis. Through a complementary, yet cyclic AMP-independent pathway, treprostinil activates PPARs, another mechanism that contributes to the anti-growth benefits of the prostacyclin class.

Olmesartan medoxomil, a prodrug, is hydrolyzed to olmesartan during absorption from the gastrointestinal tract. Olmesartan is a selective AT1 subtype angiotensin II receptor antagonist. Olmesartan blocks the vasoconstrictor effects of angiotensin II by selectively blocking the binding of angiotensin II to the AT1 receptor in vascular smooth muscle. Oral olmesartan medoxomil 10-40 mg once daily is recommended for the treatment of adult patients with hypertension, this dosage has consistently helped achieve a double-digit reduction both in systolic and diastolic blood pressure, a reduction which is maintained for one year. Extensive clinical evidence from several large well designed trials and the clinical practice setting has confirmed the antihypertensive efficacy and good tolerability profile of oral olmesartan medoxomil, as monotherapy in patients with hypertension. Olmesartan medoxomil has shown no clinically important pharmacokinetic interactions with digoxin, warfarin or antacid (aluminium magnesium hydroxide). Adverse events were infrequent in clinical studies of olmesartan medoxomil and were similar to those attributed to placebo.

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.

Trandolapril is a non-sulhydryl prodrug that belongs to the angiotensin-converting enzyme (ACE) inhibitor class of medications. It is metabolized to its biologically active diacid form, trandolaprilat, in the liver. Trandolaprilat inhibits ACE, the enzyme responsible for the conversion of angiotensin I (ATI) to angiotensin II (ATII). ATII regulates blood pressure and is a key component of the renin-angiotensin-aldosterone system (RAAS). Trandolapril may be used to treat mild to moderate hypertension, to improve survival following myocardial infarction in clinically stable patients with left ventricular dysfunction, as an adjunct treatment for congestive heart failure, and to slow the rate of progression of renal disease in hypertensive individuals with diabetes mellitus and microalbuminuria or overt nephropathy. Trandolapril is marketed by Abbott Laboratories under the brand name Mavik.

Moexiprilat is the pharmacologically active metabolite of Moexipril. Formation of Moexiprilat is caused by hydrolysis of a Moexipril’s ethyl ester group. Moexiprilat competitively inhibits ACE, thereby blocking the conversion of angiotensin I to angiotensin II. This prevents the actions of the potent vasoconstrictor angiotensin II and leads to vasodilatation. This agent also prevents angiotensin II-induced aldosterone secretion by the adrenal cortex, thereby promoting diuresis and natriuresis. Moexiprilat showed an extended duration of action owing to a long terminal pharmacokinetic half-life and produced a persistent ACE inhibition.

Moexiprilat is the pharmacologically active metabolite of Moexipril. Formation of Moexiprilat is caused by hydrolysis of a Moexipril’s ethyl ester group. Moexiprilat competitively inhibits ACE, thereby blocking the conversion of angiotensin I to angiotensin II. This prevents the actions of the potent vasoconstrictor angiotensin II and leads to vasodilatation. This agent also prevents angiotensin II-induced aldosterone secretion by the adrenal cortex, thereby promoting diuresis and natriuresis. Moexiprilat showed an extended duration of action owing to a long terminal pharmacokinetic half-life and produced a persistent ACE inhibition.