A comparison of the tolerability of the direct renin inhibitor aliskiren and lisinopril in patients with severe hypertension

Neurological complications of cardiovascular drugs

Cardiovascular drugs are used to treat arterial hypertension, hyperlipidemia, arrhythmias, heart failure, and coronary artery disease. They also include antiplatelet and anticoagulant drugs that are essential for prevention of cardiogenic embolism. Most neurologic complications of the cardiovascular drugs are minor or transient and are far outweighed by the anticipated benefits of treatment. Other neurologic complications are more serious and require early recognition and management. Overtreatment of arterial hypertension may cause lightheadedness or fatigue but often responds readily to dose adjustment or an alternative drug. Other drug complications may be more troublesome as in myalgia associated with statins or headache associated with vasodilators. The recognized bleeding risk of the antithrombotics requires careful calculation of risk/benefit ratios for individual patients. Many neurologic complications of cardiovascular drugs are well documented in clinical trials with known frequency and severity, but others are rare and recognized only in isolated case reports or small case series. This chapter draws on both sources to report the adverse effects on muscle, nerve, and brain associated with commonly used cardiovascular drugs.

Renin inhibitors versus angiotensin converting enzyme (ACE) inhibitors for primary hypertension

BACKGROUND

Renin inhibitors (RIs) reduce blood pressure more than placebo, with the magnitude of this effect thought to be similar to that for angiotensin converting enzyme (ACE) inhibitors. However, a drug's efficacy in lowering blood pressure cannot be considered as a definitive indicator of its effectiveness in reducing mortality and morbidity. The effectiveness and safety of RIs compared to ACE inhibitors in treating hypertension is unknown.

OBJECTIVES

To evaluate the benefits and harms of renin inhibitors compared to ACE inhibitors in people with primary hypertension.

SEARCH METHODS

The Cochrane Hypertension Group Information Specialist searched the following databases for randomized controlled trials up to August 2020: the Cochrane Hypertension Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also contacted authors of relevant papers about further published and unpublished work. The searches had no language restrictions.

SELECTION CRITERIA

We included randomized, active-controlled, double-blinded studies (RCTs) with at least four weeks follow-up in people with primary hypertension, which compared renin inhibitors with ACE inhibitors and reported morbidity, mortality, adverse events or blood pressure outcomes. We excluded people with proven secondary hypertension.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected the included trials, evaluated the risks of bias and entered the data for analysis.

MAIN RESULTS

We include 11 RCTs involving 13,627 participants, with a mean baseline age from 51.5 to 74.2 years. Follow-up duration ranged from four weeks to 36.6 months. There was no difference between RIs and ACE inhibitors for the outcomes: all-cause mortality: risk ratio (RR) 1.05, 95% confidence interval (CI) 0.93 to 1.18; 5 RCTs, 5962 participants; low-certainty evidence; total myocardial infarction: RR 0.86, 95% CI 0.22 to 3.39; 2 RCTs, 957 participants; very low-certainty evidence; adverse events: RR 0.98, 95% CI 0.93 to 1.03; 10 RTCs, 6007 participants;  moderate-certainty evidence; serious adverse events: RR 1.21, 95% CI 0.89 to 1.64; 10 RTCs, 6007 participants; low-certainty evidence; and withdrawal due to adverse effects: RR 0.85, 95% CI 0.68 to 1.06; 10 RTCs, 6008 participants; low-certainty evidence. No data were available for total cardiovascular events, heart failure, stroke, end-stage renal disease or change in heart rate. Low-certainty evidence suggested that RIs reduced systolic blood pressure: mean difference (MD) -1.72, 95% CI -2.47 to -0.97; 9 RCTs, 5001 participants;  and diastolic blood pressure: MD -1.18, 95% CI -1.65 to -0.72; 9 RCTs, 5001 participants,  to a greater extent than ACE inhibitors, but we judged this to be more likely due to bias than a true effect.  AUTHORS' CONCLUSIONS: For the treatment of hypertension, we have low certainty that renin inhibitors (RI) and angiotensin converting enzyme (ACE) inhibitors do not differ for all-cause mortality and myocardial infarction. We have low to moderate certainty that they do not differ for adverse events. Small reductions in blood pressure with renin inhibitors compared to ACE inhibitors are of low certainty.  More independent, large, long-term trials are needed to compare RIs with ACE inhibitors, particularly assessing morbidity and mortality outcomes, but also on blood pressure-lowering effect.

The use of aliskiren as an antifibrotic drug in experimental models: A systematic review

Aliskiren is an oral antihypertensive medication that acts by directly inhibiting renin. High levels of circulating renin and prorenin activate the pathological signaling pathway of fibrosis. This drug also reduces oxidative stress. Thus, the aim of this systematic review is to analyze experimental studies that show the actions of aliskiren on fibrosis. PubMed and LILACS databases were consulted using the keywords aliskiren and fibrosis within the period between 2005 and 2017. Fifty-three articles were analyzed. In the heart, aliskiren attenuated remodeling, hypertrophy, inflammatory cytokines, collagen deposition, and oxidative stress. In the kidneys, there was a reduction in interstitial fibrosis, the infiltration of inflammatory cells, apoptosis, proteinuria, and in the recruitment of macrophages. In diabetic models, an improvement in the albumin/creatinine relationship and in the insulin pathway in skeletal muscles was observed; aliskiren was beneficial to pancreatic function and glucose tolerance. In the liver, aliskiren reduced fibrosis, steatosis, inflammatory cytokines, and collagen deposition. In the lung and peritoneal tissues, there was a reduction in fibrosis. Many studies have reported on the beneficial effects of aliskiren on endothelial function and arterial rigidity. A reduction in fibrosis in different organs is cited by many authors, which complies with the results found in this review. However, studies diverge on the use of the drug in diabetic patients. Aliskiren has antifibrotic potential in several experimental models, interfering with the levels of fibrogenic cytokines and oxidative stress. Therefore, its use in diseases in which fibrosis plays an important pathophysiological role is suggested.

Renin Inhibition with Aliskiren: A Decade of Clinical Experience

The renin-angiotensin-aldosterone system (RAAS) plays a key role in the pathophysiology of arterial hypertension as well as in more complex mechanisms of cardiovascular and renal diseases. RAAS-blocking agents like angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers, have long been key components in the treatment of essential hypertension, heart failure, diabetic nephropathy, and chronic kidney disease, showing benefits well beyond blood pressure reduction. Renin blockade as the first step of the RAAS cascade finally became possible in 2007 with the approval of aliskiren, the first orally active direct renin inhibitor available for clinical use and the newest antihypertensive agent on the market. In the last decade, many clinical trials and meta-analyses have been conducted concerning the efficacy and safety of aliskiren in comparison to other antihypertensive agents, as well as the efficacy and potential clinical use of various combinations. Large trials with cardiovascular and renal endpoints attempted to show potential benefits of aliskiren beyond blood pressure lowering, as well as morbidity and mortality outcomes in specific populations such as diabetics, heart failure patients, and post-myocardial infarction individuals. The purpose of this review is to present the currently available data regarding established and future potential clinical uses of aliskiren.

Blood pressure lowering efficacy of renin inhibitors for primary hypertension

BACKGROUND

Hypertension is a chronic condition associated with an increased risk of mortality and morbidity. Renin is the enzyme responsible for converting angiotensinogen to angiotensin I, which is then converted to angiotensin II. Renin inhibitors are a new class of drugs that decrease blood pressure (BP) by preventing the formation of both angiotensin I and angiotensin II.

OBJECTIVES

To quantify the dose-related BP lowering efficacy of renin inhibitors compared to placebo in the treatment of primary hypertension.To determine the change in BP variability, pulse pressure, and heart rate and to evaluate adverse events (mortality, non-fatal serious adverse events, total adverse events, withdrawal due to adverse effects and specific adverse events such as dry cough, diarrhoea and angioedema).

SEARCH METHODS

The Cochrane Hypertension Information Specialist searched the following databases for randomized controlled trials (RCTs) up to February 2017: the Cochrane Hypertension Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (2017, Issue 2), MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. There was no restriction by language or publication status. We also searched the European Medicines Agency (EMA) for clinical study reports, the Novartis Clinical Study Results Database, bibliographic citations from retrieved references, and contacted authors of relevant papers regarding further published and unpublished work.

SELECTION CRITERIA

We included randomized, double-blinded, placebo-controlled studies evaluating BP lowering efficacy of fixed-dose monotherapy with renin inhibitor compared with placebo for a minimum duration of three to 12 weeks in adult patients with primary hypertension.

DATA COLLECTION AND ANALYSIS

This systematic review is a comprehensive update which includes four additional studies and extensive detail from nine clinical study reports (CSRs) of previously included studies obtained from EMA. The remaining three CSRs are not available.Two review authors independently assessed study eligibility and extracted data. In all cases where there was a difference between the CSR and the published report, data from the CSR was used. Dichotomous outcomes were reported as risk ratio (RR) with 95% confidence intervals (CIs) and continuous outcomes as mean difference (MD) with 95% CIs.

MAIN RESULTS

12 studies (mean duration of eight weeks) in 7439 mostly Caucasian patients (mean age 54 years) with mild-to-moderate uncomplicated hypertension were eligible for inclusion in the review. Aliskiren was the only renin inhibitor evaluated. All included studies were assessed to have high likelihood of attrition, reporting and funding bias.Aliskiren has a dose-related systolic/diastolic blood pressure (SBP/DBP) lowering effect as compared with placebo MD with 95% CI: aliskiren 75 mg (MD -2.97, 95% CI -4.76 to -1.18)/(MD -2.05, 95% CI -3.13 to -0.96) mm Hg (moderate-quality evidence), aliskiren 150 mg (MD -5.95, 95% CI -6.85 to -5.06)/ (MD -3.16, 95% CI -3.74 to -2.58) mm Hg (moderate-quality evidence), aliskiren 300 mg (MD -7.88, 95% CI -8.94 to -6.82)/ (MD -4.49, 95% CI -5.17 to -3.82) mm Hg (moderate-quality evidence), aliskiren 600 mg (MD -11.35, 95% CI -14.43 to -8.27)/ (MD -5.86, 95% CI -7.73 to -3.99) mm Hg (low-quality evidence). There was a dose-dependent decrease in blood pressure for aliskiren 75 mg, 150 mg and 300 mg. The blood pressure lowering effect of aliskiren 600 mg was not different from 300 mg (MD -0.61, 95% CI -2.78 to 1.56)/(MD -0.68, 95% CI -2.03 to 0.67). Aliskiren had no effect on blood pressure variability. Due to very limited information available regarding change in heart rate and pulse pressure, it was not possible to meta-analyze these outcomes.Mortality and non-fatal serious adverse events were not increased. This review found that in studies of eight week duration aliskiren may not increase withdrawal due to adverse events (low-quality evidence). Diarrhoea was increased in a dose-dependent manner (RR 7.00, 95% CI 2.48 to 19.72) with aliskiren 600 mg (low-quality evidence). The most frequent adverse events reported were headache, nasopharyngitis, diarrhoea, dizziness and fatigue.

AUTHORS' CONCLUSIONS

Compared to placebo, aliskiren lowered BP and this effect is dose-dependent. This magnitude of BP lowering effect is similar to that for angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs). There is no difference in mortality, nonfatal serious adverse events or withdrawal due to adverse effects with short term aliskiren monotherapy. Diarrhoea was considerably increased with aliskiren 600 mg.

Proteinuria and its relation to cardiovascular disease

Chronic kidney disease (CKD) and its associated morbidity pose a worldwide health problem. As well as risk of endstage renal disease requiring renal replacement therapy, cardiovascular disease is the leading cause of premature death among the CKD population. Proteinuria is a marker of renal injury that can often be detected earlier than any tangible decline in glomerular filtration rate. As well as being a risk marker for decline in renal function, proteinuria is now widely accepted as an independent risk factor for cardiovascular morbidity and mortality. This review will address the prognostic implications of proteinuria in the general population as well as other specific disease states including diabetes, hypertension and heart failure. A variety of pathophysiological mechanisms that may underlie the relationship between renal and cardiovascular disease have been proposed, including insulin resistance, inflammation, and endothelial dysfunction. As proteinuria has evolved into a therapeutic target for cardiovascular risk reduction in the clinical setting we will also review therapeutic strategies that should be considered for patients with persistent proteinuria.

Oral renin inhibitors in clinical practice: a perspective review

Hypertension is an important risk factor for cardiovascular morbidity and mortality. The importance of the renin-angiotensin-aldosterone system (RAAS) in cardiovascular and renal diseases has long been recognized: for this reason the conventional therapies, such as angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), β-blockers, and aldosterone antagonists represent the backbone of current antihypertensive therapy. Aliskiren is the first direct renin inhibitor (DRI) suitable for oral administration. By achieving more complete renin-angiotensin system inhibition, direct renin inhibitors may afford greater protection from hypertensive complications. Present evidence indicates that aliskiren reduces baseline systolic and diastolic blood pressure greater than placebo and that it is as effective as other first-line antihypertensive agents. Extra advantages can be reached when it is used in combination therapy. Clinical trials and in vitro studies also suggest that aliskiren has several cardioprotective and renoprotective effects. Therapy with aliskiren is well tolerated, but recently some concerns have arisen because of the early termination of the ALTITUDE study due to an increased incidence of adverse effects.

Safety and efficacy of aliskiren in the treatment of hypertension: a systematic overview

INTRODUCTION

Aliskiren is the first orally active direct renin inhibitor approved for the treatment of hypertension. Aliskiren's inhibitory effect on angiotensin I generation, through renin blockade, is highly specific and long-lasting (24 hours). This feature differentiates aliskiren from traditional antihypertensive drugs.

AREAS COVERED

This paper reviews the results of various clinical trials which investigate the safety and efficacy of aliskiren on blood pressure (BP) reduction and clinical end points.

EXPERT OPINION

Aliskiren is suitable for once-daily administration. Its antihypertensive effect is comparable or superior to that of other antihypertensive agents at recommended doses. The tolerability profile of aliskiren is placebo-like at the licensed doses of 150 and 300 mg. In particular, the discontinuation of therapy due to clinical adverse events occurs similarly among patients treated with either aliskiren or placebo. Aliskiren is not recommended in association with ACE-inhibitors or angiotensin II receptor blockers in patients with type 2 diabetes and renal impairment. Pending disclosure of full results, the early termination of the ALTITUDE seems to confirm previous concerns about the safety of the dual pharmacological blockade of the renin-angiotensin system in these patients. Aliskiren is a well-tolerated antihypertensive drug that may help to achieve the recommended targets of BP control.

Efficacy of aliskiren/hydrochlorothiazide combination for the treatment of hypertension: a meta-analytical approach

BACKGROUND

Single-pill combinations of aliskiren/hydrochlorothiazide have recently been approved by the European Medicines Agency for the treatment of hypertension.

OBJECTIVE

This study aimed to assess the antihypertensive efficacy of aliskiren/hydrochlorothiazide combination in reducing systolic and diastolic blood pressure in hypertensive patients.

METHODS

A search in International Pharmaceutical Abstracts, MEDLINE, The Cochrane Library and ISI Web of Knowledge was performed from 2000 to November 2009, to identify randomized, double-blind, clinical trials using aliskiren/hydrochlorothiazide for the treatment of hypertension. Studies were included if they evaluated the antihypertensive efficacy of aliskiren/hydrochlorothiazide in patients with mild or moderate essential hypertension and age ≥ 18 years. The meta-analytical approach calculated the weighted average reductions of systolic and diastolic blood pressure for each daily dosage combination.

RESULTS

We included 5 clinical trials testing several combinations of aliskiren/hydrochlorothiazide and containing data on 5448 patients. In all studies blood pressure was assessed at inclusion (baseline) and after 8 weeks of therapy. Blood pressure reductions and control rates were significantly (p < 0.05) higher with the aliskiren/hydrochlorothiazide combinations than with placebo and the same doses of aliskiren or hydrochlorothiazide alone. The weighted mean reductions (mm Hg) from baseline of systolic and diastolic blood pressure for each aliskiren/hydrochlorothiazide combination were: -15.8/-10.3 (150/25 mg); -15.9/-11.8 (300/12.5 mg); -16.9/-11.6 (300/25 mg). Blood pressure control rates (%) for the above combinations were, at least, respectively: 43.8, 50.1 and 51.9.

CONCLUSIONS

Aliskiren/hydrochlorothiazide provided clinically significant additional blood pressure reductions and improved blood pressure control rates over aliskiren or hydrochlorothiazide monotherapy.

Renin and cardiovascular disease: Worn-out path, or new direction

Inhibition of the renin angiotensin system has beneficial effects in cardiovascular prevention and treatment. The advent of orally active direct renin inhibitors adds a novel approach to antagonism of the renin-angiotensin system. Inhibition of the first and rate-limiting step of the renin angiotensin cascade offers theoretical advantages over downstream blockade. However, the recent discovery of the (pro)renin receptor which binds both renin and prorenin, and which can not only augment catalytic activity of both renin and prorenin in converting angiotensinogen to angiotensin I, but also signal intracellularly via various pathways to modulate gene expression, adds a significant level of complexity to the field. In this review, we will examine the basic and clinical data on renin and its inhibition in the context of cardiovascular pathophysiology.

First-line treatment of hypertension: critical appraisal of potential role of aliskiren and hydrochlorothiazide in a fixed combination

Arterial hypertension is one of the major diseases in the Western world. It is an independent cardiovascular risk factor and is associated with increased morbidity and mortality. Several drug classes have been shown to be effective in the treatment of hypertension. Aliskiren is a direct renin inhibitor and belongs to the class of renin-angiotensin-aldosterone system inhibitors. Several large studies have shown that aliskiren is effective in lowering blood pressure, and equivalent in this respect to the angiotensin-converting enzyme (ACE) inhibitors and the angiotensin receptor-1 blockers (ARBs). Furthermore, aliskiren has a safety and tolerability profile comparable with that of the ARBs and slightly better than that of the ACE inhibitors. From a pathophysiologic perspective, it can be combined with hydrochlorothiazide successfully, because it can block the diuretic-induced increase in plasma renin activity. Its combination with hydrochlorothiazide in a single pill has been investigated and shown to be superior to monotherapy with respect to blood pressure control and improvement in patient compliance with therapy. Further studies are needed to show whether aliskiren and its combination with hydrochlorothiazide is effective in preventing cardiovascular events and mortality when end organ damage is present.

New class of agents for treatment of hypertension: focus on direct renin inhibition

Aliskiren, the first orally active direct renin inhibitor, is an effective antihypertensive drug with distinctive characteristics, including good blockade of the renin-angiotensin system, a prolonged duration of action, pharmacologic effects that persist after drug discontinuation, and favorable tolerability comparable with placebo. The blood pressure-lowering effect of aliskiren monotherapy is similar, if not superior, to that of other first-line antihypertensive agents, and is greatly enhanced when aliskiren is combined with various other antihypertensive medications, without any adverse drug interactions. Aliskiren is also an effective and well tolerated therapy in special populations, including diabetic, obese, and elderly hypertensives. Beyond its blood pressure-lowering efficacy, results from experimental and clinical trials suggest that aliskiren has positive effects on markers of cardiovascular and renal damage. The ASPIRE (Aliskiren Study in Post-MI patients to Reduce rEmodelling) HIGHER clinical trials program is further assessing whether the promising pharmacologic properties of aliskiren translate into reduced risk of adverse cardiovascular and renal outcomes.

Renoprotection, renin inhibition, and blood pressure control: the impact of aliskiren on integrated blood pressure control

Hypertension (HTN) is an important factor in progressive loss of renal function. The kidney can be both a contributor to and a target of HTN. The functional integrity of the kidney is vital for the maintenance of cardiovascular homeostasis. Chronic activation of the renin system causes HTN and, ultimately, end-organ damage. Direct renin inhibitors (DRIs) inhibit plasma renin activity (PRA), thereby preventing the conversion of angiotensinogen to angiotensin I; consequently, the levels of both Ang I and Ang II are reduced. There is no compensatory increase in PRA activity with DRIs as seen with angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs). There are reasons to speculate that renin inhibition might prove to be a superior strategy for blocking the renin-angiotensin-aldosterone system compared with ACEIs or ARBs. Evidence for the efficacy of aliskiren (a DRI) is considered to be relatively strong, based on published, short-term, double-blind, randomized, controlled trials showing that aliskiren is as effective as other antihypertensive agents in reducing blood pressure (BP), with no rebound effects on BP after treatment withdrawal. When combined with diuretics, fully additive BP reduction is seen. When given with an ACEI or ARB, aliskiren produces significant additional BP reduction indicative of complimentary pharmacology and more complete renin-angiotensin system blockade.

Aliskiren versus ramipril in hypertension

Aliskiren is an orally active direct renin inhibitor which inhibits the synthesis of angiotensin I by linking to active renin on a deep cleft of its molecular structure, the site of hydrolysis of the Leu10-Val11 bond of angiotensinogen. At variance with angiotensin-converting enzyme (ACE) inhibitors, aliskiren eliminates the main substrate for the 'escape' phenomenon (synthesis of angiotensin II from angiotensin I through alternative enzymatic pathways). The possibility that the antihypertensive effect of aliskiren differs from that of ACE inhibitors needs to be proved in specifically designed clinical trials. Over the past 2 years, three studies have been published which directly compared aliskiren with ramipril, in patients with hypertension. We made a pooled analysis of these studies. In order to avoid interference with additional drugs, analysis was restricted to trial periods when the two drugs were given as monotherapy. In each individual study, systolic blood pressure (BP) was slightly lower with aliskiren. Overall, systolic BP was lower with aliskiren than with ramipril (weighted mean difference between the treatments 1.84 mmHg; fixed effect model; p < 0.0001; and 1.87 mmHg; random effect model; p = 0.0055). The standardized mean difference between the treatments was 2.58 (fixed effect model; p < 0.0001) and 2.92 (random effect model; p = 0.0017) in favor of aliskiren. Compared with ramipril, aliskiren may have induced a more complete 'upstream' inhibition of the renin-angiotensin-aldosterone system, with consequent greater suppression of angiotensin II. Another potential explanation may be the longer terminal elimination halflife of aliskiren (about 40 hours) compared with ramiprilat (13-17 hours). These data provide further evidence that aliskiren monotherapy provides a sustained BP reduction over the 24 hours.

Renal and cardio-protective effects of direct renin inhibition: a systematic literature review

BACKGROUND

Blockade of the renin-angiotensin-aldosterone system (RAAS) at its rate-limiting step by means of renin inhibition has led to the development of direct renin inhibitors (DRIs). Given the renal and cardioprotective effects of RAAS blockade by angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers, DRIs may increase the armamentarium for further organ protection. Over the last two decades the effects of DRIs on biomarkers for renal and cardiovascular disease have been investigated. This systematic review aims to delineate the effects of DRIs on surrogate markers of renal and cardiovascular function.

METHODS

MEDLINE and previous systematic reviews were searched for articles reported between 1980 and 2008. A standardized dataset was extracted from articles describing the effects of DRIs on markers of renal and cardiac damage and hard outcomes.

RESULTS

Fifty-two articles were included. Blood pressure reductions were generally insufficient using early generation DRIs. However, recent DRIs have greater blood pressure-lowering effects. Preclinical and clinical studies showed profound effects of DRIs on markers of renal function, including clear increases in renal plasma flow and reductions in albuminuria. These effects were observed either alone or in combination with other RAAS inhibitors and suggest potential large renal protective benefit. DRIs improved hemodynamic cardiovascular parameters, such as total peripheral resistance, arterial pressure and left ventricular mass index, to a similar extent as those observed with other RAAS inhibitors. Furthermore, addition of DRIs to optimal heart failure treatment resulted in further reductions in B-type natriuretic peptide.

CONCLUSIONS

Evidence from preclinical and clinical studies suggests that DRIs may have renal and cardiovascular effects beyond their ability to lower blood pressure. Results of ongoing hard outcome trials are awaited to definitively assess the renal and cardio-protective effects of these agents.

Direct inhibition of renin: a physiological approach to treat hypertension and cardiovascular disease

Despite the last three decades of progress in improving cardiovascular outcomes via renin–angiotensin–aldosterone system (RAAS) blockade in hypertensive patients, substantial residual morbidity/mortality remains. Attempts to improve clinical outcomes by combining angiotensin-converting enzyme inhibitors and angiotensin receptor blockers have yielded mixed results. Adverse effects of RAAS blockade with angiotensin-converting enzyme inhibitors and angiotensin receptor blockers may relate to compensatory increases in plasma renin activity (PRA). The first-in-class direct renin inhibitor, aliskiren, blocks the RAAS at its point-of-activation, suppressing PRA and attenuating increases associated with other antihypertensives. Aliskiren (with or without other agents) provides significant and prolonged blood pressure reductions in a broad range of hypertensive patients and is well tolerated. Initial results from organ-protection studies are promising. Long-term outcomes studies should yield valuable information regarding the significance of direct renin inhibition in clinical practice.

Aliskiren, the first approved renin inhibitor: Clinical application and safety in the treatment of hypertension

Hypertension is one of the most important risk factors for, and causes of, cardiovascular disease. The difficulty in achieving a normal blood pressure range in some patients makes the rate of cardiovascular disease high. For some years renin-angiotensin system inhibitors such as angiotensin-converting enzyme (ACE) and angiotensin receptor blockade have been objects of interest for treatment of cardiovascular disease. Aliskiren, the first approved renin inhibitor to reach the market, is a low molecular weight, orally active, hydrophilic nonpeptide molecule, which blocks angiotensin I generation. However it might also become a reasonable therapeutic choice in a broad number of clinical conditions, as stable coronary artery disease, cerebrovascular and cardiorenal disease, diabetes, and peripheral arterial disease. The aim of this review is to describe the effectiveness and safety of aliskerin in the treatment of hypertension.

Managing cardiovascular and renal risk: the potential of direct renin inhibition

Aliskiren is the first direct renin inhibitor for the treatment of hypertension. Clinical experience from studies in over 14,000 patients has shown that aliskiren, alone or in combination with other antihypertensive therapies, provides effective blood pressure lowering with a good safety and tolerability profile.The ultimate aim of antihypertensive therapy, however, is to reduce the risk of adverse cardiovascular and renal outcomes.The effect of aliskiren on surrogate markers of organ damage and clinical outcomes is being assessed in the ongoing ASPIRE HIGHER programme, the largest clinical trials programme in the cardio-renal disease area. Results from the ALOFT, AVOID and ALLAY studies suggest that aliskiren has positive effects on markers of cardiovascular and renal damage in patients with type 2 diabetes and nephropathy, heart failure and left ventricular hypertrophy.ASPIRE HIGHER also includes four large-scale studies assessing the potential outcome benefits of aliskiren, and the results of these trials will help define the clinical utility of aliskiren in the treatment of cardiovascular and renal diseases. In this article, we review the antihypertensive efficacy of aliskiren and explore its potential in the management of cardiovascular and renal risk.

Aliskiren: the next innovation in renin–angiotensin–aldosterone system blockade

Blockade of the renin–angiotensin–aldosterone system (RAAS) with angiotensin-converting enzyme inhibitors or Ang II-receptor blockers has been demonstrated to lower blood pressure and to be effective in heart failure and postmyocardial infarction. It is also beneficial in renal disease. These RAAS blockers further activate the RAAS, leading to an increase of plasma renin activity and plasma renin concentration. Aliskiren, the first orally active direct renin inhibitor, is an effective and well-tolerated antihypertensive agent when used as monotherapy or in combination with other antihypertensive agents in patients with mild-to-moderate hypertension. In contrast with angiotensin-converting enzyme inhibitors and Ang II-receptor blockers, aliskiren reduces plasma renin activity. A number of clinical trials with aliskiren are ongoing or completed and provide us with objective evidence regarding the clinical importance of direct renin inhibition in the treatment of cardiovascular disease.

Renin inhibition with aliskiren in hypertension: focus on aliskiren/hydrochlorothiazide combination therapy

Hypertension is a major risk factor for the development of cardiovascular and renal disease. The incidence of hypertension is increasing globally and the rate of blood pressure control remains inadequate. Renin-angiotensin-aldosterone system (RAAS) plays a crucial role in volume regulation and maintenance of blood pressure. Pathological activation of RAAS results in chronic hypertension and consequent end organ damage. Most patients with hypertension require combination therapy using agents with complimentary mechanisms of action. Hydrochlorothiazide (HCTZ) together with an agent blocking the RAAS such as an angiotensin converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) are widely used effective anti-hypertensive therapy. Aliskiren is an orally effective direct renin inhibitor that blocks the generation of angiotensin I from angiotensinogen, the rate limiting step of RAAS activation. Studies have shown equivalent antihypertensive efficacy of aliskiren when compared to existing medications such as HCTZ, ACE inhibitors and ARBs. Aliskiren has also been tested in combination therapies. The current review aims to look at the efficacy of aliskiren therapy in hypertension and the evidence for using aliskiren in combination with HCTZ.

Improving microvascular outcomes in patients with diabetes through management of hypertension

Diabetes mellitus is an independent risk factor for cardiovascular disease (CVD) and current opinion holds that hyperglycemia directly damages smaller blood vessels, resulting in microvascular complications of nephropathy, retinopathy, and neuropathy. In a patient with diabetes, hypertension compounds and greatly increases the risk of microvascular complications, and thus the risk of end-stage kidney disease, vision loss, and nontraumatic limb amputations. Hypertension and hyperglycemia directly damage the microvasculature, leading to small vessel dysfunction that manifests as the clinical disease states of diabetic retinopathy and nephropathy. Early recognition and treatment of both hyperglycemia and hypertension may prevent vision loss and chronic kidney disease, the devastating outcomes of these microvascular complications. One of the pathogenic mechanisms for microvascular dysfunction is upregulation of the angiotensin II type 1 receptor, the most physiologically common receptor for the vasoconstrictor properties of angiotensin II. In patients with diabetic retinopathy and nephropathy, tight control of blood pressure (BP) (< 130/80 mm Hg) delays the progression of retinopathy and nephropathy in addition to reducing cardiovascular morbidity and mortality. Aggressive treatment with 2 or more antihypertensive agents, selected from different drug classes, is often needed to reach the optimal BP target level. A PubMed search was conducted to identify randomized controlled trials that evaluated hypertension control and microvascular outcomes in patients with diabetes. Several clinical trials have yielded promising data with renin-angiotensin-aldosterone system (RAAS) inhibitors (the direct renin inhibitor aliskiren, angiotensin-converting enzyme inhibitors, and angiotensin receptor blockers). Attainment of BP control with RAAS inhibitors reduces the risk for CVD, nephropathy, and retinopathy. In addition, RAAS inhibitors have demonstrated renoprotective effectiveness independent of the BP reduction achieved. This review will examine the results of clinical trials in the context of BP control, diabetes, and the microvascular complications of retinopathy and nephropathy.

Antihypertensive efficacy and tolerability of aliskiren/hydrochlorothiazide (HCT) single-pill combinations in patients who are non-responsive to HCT 25 mg alone

OBJECTIVE

Thiazide diuretics such as hydrochlorothiazide (HCT) are a widely used first-line treatment for hypertension, but most patients will not achieve blood pressure (BP) control with HCT alone and so will require combination therapy. In this study the efficacy, safety and tolerability of a single-pill combination (SPC) of the direct renin inhibitor aliskiren with HCT were investigated in patients non-responsive to HCT 25 mg therapy.

METHODS

In this study, 722 patients with hypertension and an inadequate response to 4 weeks of HCT 25 mg (mean sitting diastolic BP > or =90 and <110 mmHg) were randomized to once-daily, double-blind treatment for 8 weeks with an SPC of aliskiren/HCT 300/25 mg or 150/25 mg, or continued HCT 25 mg monotherapy. Least-squares mean changes in mean sitting systolic/diastolic BP (msSBP/DBP) from double-blind baseline were analyzed for the ITT population at week 8 endpoint.

RESULTS

Aliskiren/HCT 300/25 mg and 150/25 mg SPCs lowered msSBP/DBP from baseline by 16.7/10.7 and 12.9/8.5 mmHg, respectively, both significantly greater reductions than HCT 25 mg alone (7.1/4.8 mmHg; both p < 0.001). Rates of BP control (<140/90 mmHg) were also significantly higher with aliskiren/HCT 300/25 mg (58%) and 150/25 mg (49%) than with HCT (26%; both p < 0.001). Aliskiren/HCT 300/25 mg provided significantly greater msSBP/DBP reductions and rates of BP control than the 150/25 mg SPC dose (all p < 0.05). Aliskiren/HCT SPC treatment showed similar tolerability to HCT alone and a numerically lower incidence of hypokalemia (serum potassium <3.5 mmol/L; aliskiren/HCT, 1.3-2.2%: HCT alone, 3.4%).

CONCLUSION

Aliskiren/HCT SPCs provide clinically significant BP reductions and improved BP control rates in patients who are non-responsive to HCT 25 mg monotherapy. Limitations of the study were the mainly Caucasian patient population and the non-responder design.

Macrovascular Complications of Diabetes Mellitus

Adults with diabetes mellitus frequently develop macrovascular complications. Vascular disease is a frequent cause of morbidity and mortality among patients with diabetes. Diabetes and vascular diseases remain among the most common causes of death in the United States. A number of clinical trials and practice guidelines have been published addressing the management of macrovascular complications. The cornerstone of preventing or delaying the progression of macrovascular complications of diabetes is aggressive management of hypertension and cholesterol. Angiotensin-converting enzyme inhibitors have proven effective in managing hypertension and avoiding other complications of diabetes. The body of evidence for angiotensin receptor blockers is growing in this area as well. Statins have been repeatedly proven to be the first-line agents in the management of dyslipidemia. Lifestyle modification strategies and antiplatelet therapy also remain essential. This review will focus on the role of newer diagnostic techniques, clinical trial evidence, and appropriate pharmacotherapy for macrovascular complications of diabetes.

Aliskiren: an oral direct renin inhibitor for the treatment of hypertension

Aliskiren is the first member of the new class of orally active direct renin inhibitors to receive approval from the United States Food and Drug Administration for the treatment of hypertension. In patients with hypertension, aliskiren can be used either as monotherapy or in combination with other antihypertensive agents. By inhibiting renin, aliskiren blocks the conversion of angiotensinogen to angiotensin I, which subsequently results in a reduction in angiotensin II concentrations. Unlike the angiotensin-converting enzyme inhibitors and the angiotensin II receptor blockers (ARBs), which reactively stimulate an increase in plasma renin activity, aliskiren suppresses the effects of renin and leads to a reduction in plasma renin activity. In clinical trials involving patients with mild-to-moderate hypertension, aliskiren provided antihypertensive efficacy that was comparable to that of an ARB. Combination therapy with aliskiren and an ARB may provide additional blood pressure-lowering effects compared with the respective monotherapies with each of the agents. The results from surrogate outcome studies have also alluded to the potential for aliskiren to prevent target organ damage. Because aliskiren does not significantly affect the cytochrome P450 system, it has been associated with few drug interactions. In clinical studies, aliskiren was well tolerated, and its adverse-effect profile was similar to that of placebo. Fatigue, headache, dizziness, diarrhea, nasopharyngitis, and back pain were the most commonly reported adverse events. Overall, aliskiren appears to be a reasonable treatment option for patients with mild-to-moderate hypertension who are intolerant of first-line antihypertensive therapies. Aliskiren may also be a promising renoprotective strategy in patients with concomitant hypertension and diabetes mellitus. Its potential as a first-line antihypertensive agent will have to be further examined once studies evaluating its effects on long-term clinical outcomes are completed.

Factors correlated with plasma renin activity in general Japanese population

BACKGROUND

The renin-angiotensin-aldosterone system plays a pivotal role in regulation of blood pressure and electrolyte homeostasis and is a target in the treatment of hypertension and renal diseases. However, the factors correlated with plasma renin activity (PRA) are unclarified in general Japanese population. To examine this point, we conducted a community-based cross-sectional study.

METHODS

Subjects of this study were 2,056 individuals (mean age, 61 years; 934 men; 1,122 women) over 40-year-old without antihypertensive medication in Takahata town, Japan. PRA was measured by radioimmunoassay. Estimated 24-h urine sodium (e24hUNa) and potassium excretion were calculated from morning spot urine.

RESULTS

The median value of PRA was higher in men compared to women (1.1 ng/ml/h vs. 0.7 ng/ml/h, P < 0.001). The increased PRA (>2.0 ng/ml/h) were detected in 248 men (26.3%) and 142 women (12.7%). One-factor analysis of variance showed that PRA was correlated with blood pressure, uric acid, hemoglobin, total protein, total cholesterol, low-density lipoprotein cholesterol, serum adiponectin and e24hUNa in men. In women, PRA was correlated with age, blood pressure, total protein, high-density lipoprotein cholesterol (HDL-C), serum insulin, e24hUNa and obesity. Multivariate logistic regression analysis showed that high PRA (>2.0 ng/ml/h) was independently associated with low blood pressures, low e24UNa and high serum total protein both in men and women, smoking only in men and high HDL-C only in women, respectively.

CONCLUSIONS

This study revealed that PRA was higher in men than women and was associated negatively with blood pressures and urine sodium excretion, and positively with total protein, smoking and HDL-C in Japanese population.

Aliskiren and valsartan in stage 2 hypertension: subgroup analysis of a randomized, double-blind study

INTRODUCTION

Patients with stage 2 hypertension require large absolute reductions in blood pressure (BP) to achieve recommended BP goals. Combination therapy with the direct renin inhibitor, aliskiren, and the angiotensin receptor blocker, valsartan, has been shown to produce greater BP reductions than either agent alone in a double-blind study in 1797 hypertensive patients.

METHODS

This post-hoc analysis evaluated the BP-lowering efficacy of aliskiren in combination with valsartan in a subset of patients (n=581) with stage 2 hypertension (baseline mean sitting systolic BP [msSBP] > or =160 mmHg). Patients were randomized to receive aliskiren/valsartan 150/160 mg, aliskiren 150 mg, valsartan 160 mg, or placebo once daily for 4 weeks followed by 4 weeks at double the initial dose. Mean changes from baseline in msSBP and mean sitting diastolic BP were assessed at week-8 endpoint (intent-to-treat population).

RESULTS

Aliskiren/valsartan 300/320 mg reduced BP from baseline by 22.5/11.4 mmHg at week-8 endpoint. BP reductions with combination therapy were significantly greater than with aliskiren 300 mg (17.3/8.9 mmHg, P<0.05), valsartan 320 mg (15.5/8.3 mmHg, P<0.01), or with placebo (7.9/3.7 mmHg, P<0.0001). BP control rates (<140/90 mmHg) were also significantly higher (P<0.05) with aliskiren/valsartan 300/320 mg (29.8%) compared with either aliskiren 300 mg (19.0%) or valsartan 320 mg (13.8%) monotherapy, or placebo (8.9%). All treatments were generally well tolerated.

CONCLUSION

Combination therapy with aliskiren and valsartan provided significantly greater BP reductions over aliskiren or valsartan monotherapy and is an appropriate option for management of BP in patients with stage 2 hypertension.

Blood pressure lowering efficacy of renin inhibitors for primary hypertension

BACKGROUND

Hypertension is a chronic condition associated with an increased risk of mortality and morbidity. The renin-angiotensin-aldosterone system is an important target site for five antihypertensive drug classes: beta blockers, renin inhibitors, ACE inhibitors, angiotensin receptor blockers (ARBs) and aldosterone inhibitors. Renin is the enzyme responsible for converting angiotensinogen to angiotensin I, which is then converted to angiotensin II. Renin inhibitors prevent the formation of both angiotensin I and angiotensin II . Renin inhibitors do not affect kinin metabolism and may produce fewer adverse effects than ACE inhibitors such as dry cough or angioedema.

OBJECTIVES

To quantify the dose-related blood pressure lowering efficacy of renin inhibitors versus placebo in the treatment of primary hypertension.

SEARCH STRATEGY

We searched the following databases for randomised, double blind, placebo-controlled trials of renin inhibitors: Medline (1966-March 2008), EMBASE (1988-March 2008), Cochrane CENTRAL, and bibliographic citations from retrieved references. No language restrictions were applied.

SELECTION CRITERIA

Study design had to meet the following criteria: double-blinded, placebo-controlled; random allocation to a specific dose of renin inhibitor group and parallel placebo group; duration of follow-up of at least three weeks.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed trial quality using risk of bias tables. Disagreements were resolved by discussion or a third reviewer. Data synthesis and analyses were done using the Cochrane Review Manager software, RevMan 5. Data for continuous variables were combined using a weighted mean difference method. Dichotomous variables were analysed using relative risk.

MAIN RESULTS

Six trials (N=3694) met the inclusion criteria for this review. Aliskiren was the only renin inhibitor studied in these studies. The meta-analysis shows that aliskiren has a dose-related both systolic/diastolic blood pressure lowering effect as compared to placebo: aliskiren 75 mg -2.9/-2.3 mmHg, aliskiren 150 mg -5.5/-3.0 mmHg, aliskiren 300 mg -8.7/-5.0, aliskiren 600 mg -11.4/-6.6 mmHg. Aliskiren 300 mg significantly lowered both SBP and DBP as compared to aliskiren 150 mg (SBP:-2.97 (95% CI -3.99, -1.95) and DBP: -1.66 (95% CI -2.32, -1.0). Aliskiren has no effect on blood pressure variability. No data was available to assess the effect of aliskiren on heart rate and pulse pressure. This review found weak evidence that with short- term use, aliskiren does not increase withdrawals due to adverse effects as compared to placebo.

AUTHORS' CONCLUSIONS

Aliskiren has a dose-related blood pressure lowering effect better than placebo. This effect is similar to that determined for ACE inhibitors and ARBs.

Direct renin inhibition: an evaluation of the safety and tolerability of aliskiren

BACKGROUND

Aliskiren, an antihypertensive drug approved in the United States and Europe, is the first in a new class known as direct renin inhibitors. Aliskiren has been evaluated for safety and tolerability in more than 6400 patients. It has demonstrated a favorable safety and tolerability profile alone or in combination with other drugs.

OBJECTIVE

This article reviews the currently available safety and tolerability data for aliskiren.

METHODOLOGY

Using the search term aliskiren, MEDLINE (no timeframe set) and major cardiovascular congresses (2005-2008) were searched. Articles and abstracts with safety and drug interaction data were included.

FINDINGS

Aliskiren may share common adverse effects observed with angiotensin-converting enzyme (ACE)-inhibitor and angiotensin receptor blocker (ARB) therapy. In placebo-controlled trials, those commonly reported for aliskiren at the approved dosage were headache, diarrhea, for personal and fatigue, with incidences similar to those of placebo. Aliskiren has been well tolerated in black, geriatric, diabetic, or obese patients and patients with renal or hepatic impairment. Aliskiren neither inhibits nor induces the cytochrome P450 system; it does not inhibit P-glycoprotein, but is a substrate for this drug transporter. Adding a direct renin inhibitor to another renin-angiotensin-aldosterone system (RAAS) inhibitor may further improve cardiovascular outcomes, renal outcomes, or both, without increasing the incidence of adverse effects.

CONCLUSIONS

Aliskiren is well tolerated, has an adverse effect profile comparable to that of placebo, and has a low potential for drug interactions. Data from ongoing trials evaluating the effects of aliskiren on surrogate markers, morbidity, and mortality will further define the role of direct renin inhibition in the antihypertensive armamentarium.

Aliskiren

Aliskiren is the first orally active inhibitor of renin to be approved for clinical use as an antihypertensive agent. The development program has established that at the licensed doses of 150 mg and 300 mg, there are dose-related falls in blood pressure comparable to those seen with other major classes of antihypertensive drugs and that these falls are associated with a placebo level of side effects. Aliskiren was found to be effective either as monotherapy or in combination with drugs from the other major classes. As expected, there was a greater benefit from adding aliskiren to natriuretic drugs than to other blockers of the renin system. However, there was also some consistent benefit from dual renin blockade. Aliskiren is likely to be of most value in patients uncontrolled by, or intolerant of, other classes. Rational understanding of the renin system will maximize its value, for instance, by encouraging greater use of natriuretic agents in patients with resistant hypertension to render their hypertension renin dependent. Whether there are cardiovascular benefits other than blood pressure control in blocking the renin system remains to be demonstrated. It is hoped that long-term outcome studies with aliskiren will finally allow this question to be answered.

Aliskiren

PURPOSE

The pharmacology, bioavailability and pharmacokinetics, clinical efficacy, adverse effects and toxicity, drug interactions, and dosage and administration of aliskiren as well as safety and economic issues related to its use are reviewed.

SUMMARY

Aliskiren is the first of a new class of antihypertensive agents, direct renin inhibitors, that act by blocking the rate- limiting step of the renin-angiotensin- aldosterone system (RAAS). It was approved by the Food and Drug Administration in 2007 for use as monotherapy or in combination with other antihypertensives. Clinical studies comparing aliskiren monotherapy with placebo indicated a dose-dependent reduction in both systolic and diastolic blood pressure (BP). Greater reductions in BP have been achieved when aliskiren was used in combination with hydrochlorothiazide or an angiotensin-receptor blocker. The most common adverse effects reported in clinical trials were headache, fatigue, dizziness, diarrhea, and nasopharyngitis. Aliskiren has not been studied in patients with moderate renal dysfunction; as a RAAS-acting drug, it should be prescribed for such patients only with caution.

CONCLUSION

Aliskiren at a dosage of 150 or 300 mg daily may be a good option for control of mild-to-moderate hypertension in patients with or without diabetes in whom first-line antihypertensives have failed to adequately control BP; comparative studies with other antihypertensives are needed to determine which patients can most benefit from aliskiren therapy.

Treating hypertension while protecting the vulnerable islet in the cardiometabolic syndrome

Hypertension, a multifactorial-polygenic disease, interacts with multiple environmental stressors and results in functional and structural changes in numerous end organs, including the cardiovascular system. This can result in coronary heart disease, stroke, peripheral vascular disease, congestive heart failure, end-stage renal disease, insulin resistance, and damage to the pancreatic islet. Hypertension is the most important modifiable risk factor for major health problems encountered in clinical practice. Whereas hypertension was once thought to be a medical condition based on discrete blood pressure readings, a new concept has emerged defining hypertension as part of a complex and progressive metabolic and cardiovascular disease, an important part of a cardiometabolic syndrome. The central role of insulin resistance, oxidative stress, endothelial dysfunction, metabolic signaling defects within tissues, and the role of enhanced tissue renin-angiotensin-aldosterone system activity as it relates to hypertension and type 2 diabetes mellitus are emphasized. Additionally, this review focuses on the effect of hypertension on functional and structural changes associated with the vulnerable pancreatic islet. Various classes of antihypertensive drugs are reviewed, especially their roles in delaying or preventing damage to the vulnerable pancreatic islet, and thus delaying the development of type 2 diabetes mellitus.

Renin inhibition with aliskiren

1. Initial attempts to inhibit renin in humans have faced numerous difficulties. Molecular modelling and X-ray crystallography of the active site of renin have led to the development of new orally active renin inhibitors, such as aliskiren. 2. Aliskiren has a low bioavailability (between 2.6 and 5.0%) compensated by its high potency to inhibit renin (IC50: 0.6 nmol/L) and a long plasma half-life (23-36 h), which makes it suitable for once-daily dosing. 3. The once-daily administration of aliskiren to hypertensive patients lowers BP as strongly as standard doses of established angiotensin II type 1 (AT1) receptor blockers (losartan, valsartan, irbesartan), hydrochlorothiazide, angiotensin converting enzyme inhibitors (ramipril and lisinopril) or long acting calcium channel blockers (amlodipine). In combination therapy, aliskiren further decreases blood pressure when combined with either hydrochlorothiazide, amlodipine, irbesartan or ramipril. 4. The biochemical consequences of renin inhibition differ from those of angiotensin I-converting enzyme (ACE) inhibition and Ang II antagonism, particularly in terms of angiotensin profiles and interactions with the bradykinin-nitric oxide-cyclic guanosine monophosphate pathway and possibly the (pro)renin receptor. 5. Blockade of the renin angiotensin system (RAS) with ACE inhibitors, AT1 receptor blockers or a combination of these drugs has become one of the most successful therapeutic approaches in medicine. However, it remains unclear how to optimize RAS blockade to maximize cardiovascular and renal benefits. In this context, renin inhibition to render the RAS fully quiescent is a new possibility requiring further study.

Renin inhibitors, clinical experience

The inhibition of the renin-angiotensin system is one of the most commonly utilized ways to lower blood pressure in patients with arterial hypertension. Up till now, angiotensin-converting enzyme inhibitors as well as angiotensin receptor blockers are the established inhibitors of this system, and both classes are used in clinical routine. There is a wealth of information about those classes, which are known not only to lower blood pressure, but also to prevent end-organ damage and, ultimately, reduce mortality in patients. Direct renin inhibition was already targeted 30 years ago to inhibit the renin-angiotensin system, but low bioavailability and short duration of action of the first generations of renin inhibitors withheld their clinical success. With the new generation of non-peptide orally available renin inhibitors, a third substance to inhibit the renin-angiotensin system is on the market, and the prototype of this class, aliskiren, has now been tested in various clinical trials in arterial hypertension. We review the studies of aliskiren and discuss its current role in the contemporary treatment of arterial hypertension as well as the possible new fields of action for aliskiren in treating heart failure and diabetic nephropathy.

The renin angiotensin system in the development of cardiovascular disease: role of aliskiren in risk reduction

An association has been shown between plasma renin activity (PRA) and the risk of cardiovascular disease. There is also evidence that angiotensin II exerts detrimental effects on progression and instabilization of atherosclerotic plaque. The renin-angiotensin system (RAS) can be inhibited through inhibition of angiotensin I (Ang I) generation from angiotensinogen by direct renin inhibitors, inhibition of angiotensin II (Ang II) generation from angiotensin I by angiotensin-converting enzyme inhibitors and finally by direct inhibition of the action of Ang II receptor level. Aliskiren, the first direct renin inhibitor to reach the market, is a low-molecular-weight, orally active, hydrophilic nonpeptide. Aliskiren blocks Ang I generation, while plasma renin concentration increases because the drugs blocks the negative feed-back exerted by Ang II on renin synthesis. Because of its long pharmacological half-life, aliskiren is suitable for once-daily administration. Its through-to-peak ratio approximates 98% for the 300 mg/day dose. Because of its mechanism of action, aliskiren might offer the additional opportunity to inhibit progression of atherosclerosis at tissue level. Hypertension is an approved indication for this drug, which is also promising for the treatment of heart failure. The efficacy of this drug in reducing major clinical events is being tested in large ongoing clinical trials.