Systematic Review of Combined Angiotensin-Converting Enzyme Inhibition and Angiotensin Receptor Blockade in Hypertension

Trajectories of adherence to ACEI/ARB medications following a motivational interviewing intervention among Medicare Advantage beneficiaries in Texas

OBJECTIVES

To assess the impact of student telephone motivational interviewing intervention on angiotensin-converting enzyme inhibitors/angiotensin-receptor blockers (ACEI/ARBs) adherence trajectories and identify predictors of each trajectory.

METHODS

The intervention group included continuously enrolled Medicare Advantage Plan patients non-adherent to ACEI/ARBs vs the control group (1:2 ratio). The intervention was tailored by pre-intervention trajectories and included an initial and five follow-up calls. Adherence was measured 6 months after initial calls using the proportion of days covered (PDC). Monthly PDCs were integrated into a group-based trajectory model and categorized patients into 4-groups. A multinomial logistic regression model was used to evaluate trajectory predictors.

RESULTS

The study comprised 240 intervention patients and 480 controls with four trajectories: adherent trajectory 44.2%, gradual improvement in adherence 13.4%, slow decline in adherence 24.1%, and discontinuation 18.3%. Patients with the intervention were less likely to experience a slow decline in adherence than controls (OR: 0.627 [0.401-0.981]). Patients with specialty prescribers' visits, ≥ 1 previous hospitalization, rapid decline in adherence as pre-intervention trajectory, and higher CMS risk score were associated with discontinuation trajectory.

CONCLUSION

Intervention patients vs controls had a lower likelihood of following a slow decline in adherence pattern.

PRACTICE IMPLICATIONS

This study underscores the importance of individualized interventions and the association between past adherence patterns and post-intervention trajectories.

Role of hypertension in progression of pediatric CKD

Hypertension is frequent in children with chronic kidney disease (CKD). Its prevalence varies according to CKD stage and cause. It is relatively uncommon in children with congenital kidney disease, while acquired kidney disease is associated with a higher prevalence of hypertension. Studies in children with CKD utilizing ambulatory blood pressure monitoring also showed a high prevalence of masked hypertension. Uncontrolled and longstanding hypertension in children is associated with progression of CKD. Aggressive treatment of high blood pressure should be an essential part of care to delay CKD progression in children.

The association between dual RAAS inhibition and risk of acute kidney injury and hyperkalemia in patients with diabetic kidney disease: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

Dual renin-angiotensin-aldosterone system (RAAS) blockade involves dual therapy with a combination of angiotensin-converting enzyme inhibitors (ACEis), angiotensin-receptor blockers (ARBs), direct renin inhibitors (DRIs), or mineralocorticoid receptor antagonists (MRAs). It is hypothesized that dual RAAS blockade would result in a more complete inhibition of the RAAS cascade. However, large clinical trials on dual RAAS inhibition have shown increased risk of acute kidney injury (AKI) and hyperkalemia without additional benefit on mortality, cardiovascular events, or chronic kidney disease (CKD) progression compared to RAAS inhibitor monotherapy in patients with diabetic kidney disease (DKD). The development of newer, more selective non-steroidal MRAs as cardiorenal protective therapies has created a new opportunity for dual RAAS inhibition. We conducted a systematic review and meta-analysis of the risks of AKI and hyperkalemia with dual RAAS blockade in patients with DKD.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

This is a systematic review and meta-analysis of the randomized controlled trials (RCT) published from 1 January 2006 to 30 May 2022. The study population included adult patients with DKD receiving dual RAAS blockade. A total of 31 RCTs and 33 048 patients were included in the systematic review. Pooled risk ratios (RRs) and 95% confidence intervals (CIs) were calculated using random effects.

RESULTS

There were 208 AKI events in 2690 patients on ACEi + ARB versus 170 in 4264 patients with ACEi or ARB monotherapy (pooled RR 1.48, 95% CI: 1.23-1.39). There were 304 hyperkalemia events in 2818 patients on ACEi + ARB versus 208 in 4396 patients with ACEi or ARB monotherapy (pooled RR 1.97, 95% CI: 1.32-2.94). A non-steroidal MRA + ACEi or ARB showed no increase in the risk of AKI (pooled RR 0.97, 95% CI: 0.81-1.16) compared to ACEi or ARB monotherapy but had a 2-fold higher risk of hyperkalemia with 953 events in 7837 patients in dual therapy versus 454 events in 6895 patients in monotherapy (pooled RR 2.05, 95% CI: 1.84-2.28). A steroidal MRA + ACEi or ARB had a 5-fold higher risk of hyperkalemia with 28 events in 245 at risk in dual therapy versus five events in 248 at risk in monotherapy (pooled RR 5.42 95% CI: 2.15-13.67).

CONCLUSION

Dual therapy with RAASi is associated with an increased risk of AKI and hyperkalemia compared to RAASi monotherapy. Conversely, dual therapy with RAAS inhibitors and non-steroidal MRAs have no additional risk of AKI but a similar risk of hyperkalemia, which is lower than dual therapy with RAAS inhibitors and steroidal MRAs.

Neurogenic Hypertension, the Blood-Brain Barrier, and the Potential Role of Targeted Nanotherapeutics

Hypertension is a major health concern globally. Elevated blood pressure, initiated and maintained by the brain, is defined as neurogenic hypertension (NH), which accounts for nearly half of all hypertension cases. A significant increase in angiotensin II-mediated sympathetic nervous system activity within the brain is known to be the key driving force behind NH. Blood pressure control in NH has been demonstrated through intracerebrovascular injection of agents that reduce the sympathetic influence on cardiac functions. However, traditional antihypertensive agents lack effective brain permeation, making NH management extremely challenging. Therefore, developing strategies that allow brain-targeted delivery of antihypertensives at the therapeutic level is crucial. Targeting nanotherapeutics have become popular in delivering therapeutics to hard-to-reach regions of the body, including the brain. Despite the frequent use of nanotherapeutics in other pathological conditions such as cancer, their use in hypertension has received very little attention. This review discusses the underlying pathophysiology and current management strategies for NH, as well as the potential role of targeted therapeutics in improving current treatment strategies.

Effect of Sequential Nephron Blockade versus Dual Renin-Angiotensin System Blockade Plus Bisoprolol in the Treatment of Resistant Hypertension, a Randomized Controlled Trial (Resistant Hypertension on Treatment - ResHypOT)

Introduction

Hypertension is the most important modifiable risk factor for cardiovascular disease and a leading public health concern.

Objectives

The primary aim was to compare sequential nephron blockade (SNB) versus dual renin-angiotensin system blockade (DRASB) plus bisoprolol in patients with resistant hypertension to observe reductions in systolic and diastolic blood pressure (SBP and DBP) levels after 20 weeks of treatment.

Material and Methods

This trial was an open-label, prospective, randomized, parallel-group, clinical study with optional drug up-titration. Participants were evaluated during five visits at 28-day intervals.

Results

The mean age was 55.5 years in the SNB and 58.4 years in the DRASB + bisoprolol group (p=NS). Significant office BP reductions were observed in both groups. SNB group, SBP decreased from 174.5±21.0 to 127.0±14.74 mmHg (p<0.0001), and DBP decreased from 105.3±15.5 to 78.11±9.28 mmHg (p<0.0001). DRASB group, SBP decreased from 178.4±21.08 to 134.4 ± 23.25 mmHg (p<0.0001) and DBP decreased from 102.7±11.07 to 77.33±13.75 mmHg (p<0.0001). Ambulatory blood pressure monitoring (ABPM) showed also significant SBP and DBP reductions in both groups (p<0.0001).

Conclusion

In patients with RHTN adherent to treatment, SNB and DRASB plus bisoprolol showed excellent therapeutic efficacy, although SNB was associated with earlier SBP reduction.

Antiproteinuric and Hyperkalemic Mechanisms Activated by Dual Versus Single Blockade of the RAS in Renovascular Hypertensive Rats

This study aimed to investigate the antiproteinuric and hyperkalemic mechanisms activated by dual renin-angiotensin system (RAS) blockade in renovascular hypertensive rats (2-kidney 1-clip model [2K-1C]). Six weeks after clipping the left renal artery or sham operation (2K), rats were treated with losartan, enalapril, or both drugs for two weeks. We found that 2K-1C rats displayed higher tail-cuff blood pressure (BP), increased non-clipped kidney Ang II concentration, and more pronounced urinary albumin excretion than 2K. BP was decreased by the treatment with either enalapril or losartan, and the combination of both drugs promoted an additional antihypertensive effect in 2K-1C rats. Renal Ang II content and albuminuria were reduced by either enalapril or losartan in monotherapy and restored to control levels by dual RAS blockade. Albuminuria in 2K-1C rats was accompanied by downregulation of the glomerular slit protein podocin, reduction of the endocytic receptors megalin and cubilin, and a marked decrease in the expression of the ClC-5 chloride channel, compared to 2K animals. Treatment with losartan and enalapril in monotherapy or combination increased the expression of podocin, cubilin, and ClC-5. However, only the combined therapy normalized podocin, cubilin, and ClC-5 protein abundance in the non-clipped kidney of 2K-1C rats. Renovascular hypertensive 2K-1C rats had a lower concentration of plasma potassium compared to 2K rats. Single RAS blockade normalized potassium plasma concentration, whereas 2K-1C rats treated with dual RAS blockade exhibited hyperkalemia. Hypokalemia in 2K-1C rats was accompanied by an increase in the cleaved activated forms of α-ENaC and γ-ENaC and the expression of β-ENaC. Combined RAS blockade but not monotherapy significantly reduced the expression of these ENaC subunits in 2K-1C rats. Indeed, double RAS blockade reduced the abundance of cleaved-α-ENaC to levels lower than those of 2K rats. Collectively, these results demonstrate that the antiproteinuric effect of dual RAS blockade in 2K-1C rats is associated with the restored abundance of podocin and cubilin, and ClC-5. Moreover, double RAS blockade-induced hyperkalemia may be due, at least partially, to an exaggerated downregulation of cleaved α-ENaC in the non-clipped kidney of renovascular hypertensive rats.

Modeling the Molecular Impact of SARS-CoV-2 Infection on the Renin-Angiotensin System

SARS-CoV-2 infection is mediated by the binding of its spike protein to the angiotensin-converting enzyme 2 (ACE2), which plays a pivotal role in the renin-angiotensin system (RAS). The study of RAS dysregulation due to SARS-CoV-2 infection is fundamentally important for a better understanding of the pathogenic mechanisms and risk factors associated with COVID-19 coronavirus disease and to design effective therapeutic strategies. In this context, we developed a mathematical model of RAS based on data regarding protein and peptide concentrations; the model was tested on clinical data from healthy normotensive and hypertensive individuals. We used our model to analyze the impact of SARS-CoV-2 infection on RAS, which we modeled through a downregulation of ACE2 as a function of viral load. We also used it to predict the effect of RAS-targeting drugs, such as RAS-blockers, human recombinant ACE2, and angiotensin 1-7 peptide, on COVID-19 patients; the model predicted an improvement of the clinical outcome for some drugs and a worsening for others. Our model and its predictions constitute a valuable framework for in silico testing of hypotheses about the COVID-19 pathogenic mechanisms and the effect of drugs aiming to restore RAS functionality.

Reversion of cardiovascular remodelling in renovascular hypertensive 2K-1C rats by renin-angiotensin system inhibitors

OBJECTIVES

Evaluate whether the RAS dual blockade would induce additional beneficial effects on cardiovascular remodelling when compared to monotherapy in renal hypertensive two kidneys-one clip (2K-1C) rats.

METHODS

Hypertensive 2K-1C and normotensive (2K) rats were treated for 14 days with submaximal doses of losartan (LOS), enalapril (ENA), losartan plus enalapril (LOS + ENA) or vehicle (water). Blood pressure and some parameters of cardiovascular remodelling were evaluated.

RESULTS

Systolic blood pressure (SBP) was higher in 2K-1C (209 ± 3 mm Hg, P < .05) than in 2K (113 ± 1 mm Hg) rats. There was an additional effect in 2K-1C treated with LOS + ENA (153 ± 9 mm Hg) on lowering SBP when compared to LOS (184 ± 12 mm Hg) or ENA (177 ± 9 mm Hg). None of the treatments had effect on SBP in 2K rats. In 2K-1C, cardiomyocyte hypertrophy was reduced by all treatments, although the cardiac hypertrophy indexes remained unchanged. 2K-1C aortas presented medial thickening that was partially reduced by the treatments. Intimal hyperplasia observed in 2K-1C (15.56 ± 0.89 µm vs 8.24 ± 0.80 µm) was reversed by ENA (9.52 ± 0.45 µm) or LOS + ENA (8.17 ± 0.53 µm). Collagen deposition was increased in 2K-1C hearts (1.77 ± 0.16 vs 1.28 ± 0.09) and aortas (8.1 ± 0.6 vs 5.2 ± 0.2). Treatment with LOS reduced (1.12 ± 0.14%) and ENA (0.81 ± 0.11%) or LOS + ENA (0.86 ± 0.11%) additionally diminished collagen only in 2K-1C hearts.

CONCLUSIONS

Submaximal doses of ACEi and/or ARB have inhibitory actions on cardiac remodelling and vascular hypertrophy not entirely dependent on their effects on blood pressure normalization in renovascular hypertensive rats. Combined therapy produced additional reduction in blood pressure than monotherapy despite a similar inhibition on cardiovascular remodelling.

Efficacy and Safety of Dual Blockade of the Renin-Angiotensin-Aldosterone System in Diabetic Kidney Disease: A Meta-Analysis

INTRODUCTION

Current guidelines recommend renin-angiotensin-aldosterone system (RAAS) inhibitors in the treatment of diabetic kidney disease (DKD). However, evidence suggests that the combined use of RAAS blockers may be associated with increased rates of adverse events.

OBJECTIVES

Our objective was to examine the efficacy and safety of dual blockade of the RAAS in patients with DKD.

METHODS

This was a systematic review and meta-analysis of randomized controlled trials (RCTs) published between January 1990 and January 2018 sourced via the PubMed, EMBASE, and Cochrane Library databases. RCTs were included if they investigated the efficacy and safety of dual blockade therapy compared with monotherapy in patients with DKD. Random effects models were used in meta-analysis to account for heterogeneities in effect sizes across the reviewed studies. Analyses were stratified by blood pressure and albuminuria. We further conducted subgroup analyses by considering various combinations of RAAS inhibitors.

RESULTS

Based on 42 RCTs with 14,576 patients, dual RAAS blockade therapy was associated with significant decreases in blood pressure, albuminuria, and proteinuria. However, dual therapy was not superior to monotherapy in terms of reductions in all-cause mortality, cardiovascular mortality, or progression to end-stage renal disease (ESRD). Significant increases in serum potassium and rates of hyperkalemia and hypotension were more common in patients treated with dual therapy. However, glomerular filtration rates (GFR) did not decrease significantly with dual therapy. In subgroup analysis, an angiotensin-converting enzyme inhibitor (ACEI) plus an angiotensin-receptor blocker (ARB) or a direct renin inhibitor (DRI) plus an ACEI/ARB did not significantly increase the risk of hyperkalemia, hypotension, and adverse events, and the risk of hypotension increased significantly within the normotensive subgroup but not within the hypertensive subgroup. The risk of hyperkalemia increased significantly in patients with DKD with macroalbuminuria but not in those with microalbuminuria.

CONCLUSION

Dual inhibition therapy is superior to monotherapy for blood pressure control and urine protein reduction, though such superiority does not translate into improvements in longer-term outcomes, such as reduced progression to ESRD, all-cause mortality, and cardiovascular mortality. An ACEI plus an ARB or a DRI plus an ACEI/ARB may be a safe and effective therapy for patients with DKD, and combination therapy may be suitable for patients with DKD and hypertension and microalbuminuria.

Angiotensin-converting enzyme inhibitors or angiotensin receptor blocker monotherapy retard deterioration of renal function in Taiwanese chronic kidney disease population

It remains unclear how different uses of angiotensin-converting inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) influence the progression of chronic kidney disease (CKD). This study explored CKD progression in a multicentre, longitudinal cohort study that included 2639 patients with CKD stage 1–5 and hypertension. Patients treated with ACEI or ARB for ≥90 days during a 6-mo period comprised the study group, or no treatment, comprised the control group. The study group was subdivided on the basis of treatment: ACEI monotherapy or ARB monotherapy. Progression of renal deterioration was defined by an average eGFR decline of more than 5 mL/min/1.73 m²/yr or the commencement of dialysis. With at least 1-year follow up, a progression of renal deterioration was demonstrated in 29.70% of the control group and 25.09% of the study group. Patients in the study group had significantly reduced progression of CKD with adjusted odds ratio 0.79 (95% confidence interval: 0.63–0.99). However, when ACEI monotherapy and ARB monotherapy were analyzed separately, none of their associations with CKD progression was statistically significant. In conclusion, ACEI or ARB monotherapy may retard the deterioration of renal function among patients with CKD and hypertension.

А theoretical study on ionization of sartans in aqueous media and on interactions with surfactant micelles

The ionization order of sartans in aqueous media and possible way of interactions between their equilibrium forms and surfactant micelles have been theoretically investigated. The examined sartans are ampholytes (irbesartan and losartan) and a diacid (valsartan) with the close values of ionization constants. In order to get a better insight in the overlapped protolytic equilibria of sartans and to predict an affinity of the equilibrium forms interacting with micelles as biomembrane mimetic systems, the theoretical study was performed. Energy calculation of the optimized structures of the equilibrium forms was performed at the B3LYP/6-31G (d,p) level of the Density Functional Theory (DFT). The results of the theoretical study helped to assign the experimentally determined pK_a values to the corresponding ionizable centers and confirmed that in all examined compounds, the higher pK_a values can be attributed to ionization of tetrazole. The molecular descriptor values showed that sartans interact predominantly with the micelle surfaces. The equilibrium forms of ampholytes demonstrate higher affinity to the micelles, as compared to the forms of the diprotic acid. Additionally, it was shown that the uncharged molecular forms of ampholytes are more lipophylic then their zwitterionic forms.

Additive effect of simultaneous continuous administration of degarelix and TAK-448 on LH suppression in a castrated rat model

Gonadotropin releasing hormone (GnRH) analogs have long been used in androgen deprivation therapy (ADT) in the treatment of prostate cancer. Chronic administration of either GnRH agonists or antagonists leads to suppression of testosterone production in the testes via either downregulation or direct blockade of the GnRH receptor in the pituitary, respectively. Chronic administration of kisspeptin analogs has more recently been shown to lead to testosterone suppression via desensitization of GnRH neurons in the hypothalamus and an optimized kisspeptin analog, TAK-448, was proven effective in a small phase 1 trial. The current study explored the hypothesis that co-administration of TAK-448 and the GnRH antagonist, degarelix, would have an additive effect on hormonal suppression, as a result of simultaneous intervention in separate steps in the same pathway. TAK-448 or degarelix were first administered individually to castrated rats in order to identify low doses capable of partial or no suppression of luteinizing hormone (LH). In the second step, combinations of the low doses of TAK-448 and degarelix were assessed in a 14 day study and compared to the drugs administered separately. The results showed that simultaneous intervention at the kisspeptin and GnRH receptors caused a more pronounced LH suppression than either drug alone, demonstrating an additive or potentiating effect. These results suggest that such a drug combination may hold promise as novel forms of androgen deprivation therapy in the treatment of prostate cancer.

The effects of single and combined application of ramipril and losartan on renal structure and function in hypertensive rats

The objective of the present study was to investigate the effects of single and combined administration of ramipril and losartan on renal structure and function in spontaneously hypertensive rats (SHRs). Thirty-two 9-week-old SHRs and eight Wistar-Kyoto (WKY) rats were randomly divided into five groups: the WKY control group, the SHR control group, the SHR-ramipril group, the SHR-losartan group, and the SHR-combined mediation group. The rat body weight, SBP, heart rate, and urinary albumin excretion rate (UAER) were measured. (1) The SBP was reduced to the normal level in all groups of rats except for the SHR control group. Combined administration of ramipril and losartan can be reduced to the normal level earlier than single (P < 0.01). (2) The SHR-ramipril group and the SHR-losartan group still experienced a higher UAER than that in the WKY control group (P < 0.01). (3) The renal mass/BW ratio was decreased in the SHR-ramipril group, SHR-losartan group, and SHR-combined medication group compared to that in the SHR control group (P < 0.01). (4) Compared with the SHR control group, the SHR-ramipril group, the SHR-losartan group, and the SHR-combined medication group had a lower percentage of the IOD of glomerular collagen relative to the glomerular area (P < 0.01). (5) The reduction in tubulointerstitial injury score was more significant in the SHR-combined medication group than in the SHR-ramipril group and the SHR-losartan group (P < 0.01). The combination of ramipril and losartan is superior to either single drug in reducing the UAER, resisting glomerular collagen deposition, and protecting renal tubular structure.

Dual Blockade of the Renin-angiotensin-aldosterone System in Type 2 Diabetic Kidney Disease

Objective:

To examine the efficacy and safety of dual blockade of the renin-angiotensin-aldosterone system (RAAS) among patients with type 2 diabetic kidney disease.

Data Sources:

We searched the major literature repositories, including the Cochrane Central Register of Controlled Trials, MEDLINE and EMBASE, for randomized clinical trials published between January 1990 and October 2015 that compared the efficacy and safety of the use of dual blockade of the RAAS versus the use of monotherapy, without applying any language restrictions. Keywords for the searches included “diabetic nephropathy,” “chronic kidney disease,” “chronic renal insufficiency,” “diabetes mellitus,” “dual therapy,” “combined therapy,” “dual blockade,” “renin-angiotensin system,” “angiotensin-converting enzyme inhibitor,” “angiotensin-receptor blocker,” “aldosterone blockade,” “selective aldosterone blockade,” “renin inhibitor,” “direct renin inhibitor,” “mineralocorticoid receptor blocker,” etc.

Study Selection:

The selected articles were carefully reviewed. We excluded randomized clinical trials in which the kidney damage of patients was related to diseases other than diabetes mellitus.

Results:

Combination treatment with an angiotensin-converting enzyme inhibitor supplemented by an angiotensin II receptor blocking agent is expected to provide a more complete blockade of the RAAS and a better control of hypertension. However, existing literature has presented mixed results, in particular, related to patient safety. In view of this, we conducted a comprehensive literature review in order to explain the rationale for dual blockade of the RAAS, and to discuss the pros and cons.

Conclusions:

Despite the negative results of some recent large-scale studies, it may be immature to declare that the dual blockade is a failure because of the complex nature of the RAAS surrounding its diversified functions and utility. Further trials are warranted to study the combination therapy as an evidence-based practice.

Perivascular adipose tissue as a regulator of vascular disease pathogenesis: identifying novel therapeutic targets

Adipose tissue (AT) is an active endocrine organ with the ability to dynamically secrete a wide range of adipocytokines. Importantly, its secretory profile is altered in various cardiovascular disease states. AT surrounding vessels, or perivascular AT (PVAT), is recognized in particular as an important local regulator of vascular function and dysfunction. Specifically, PVAT has the ability to sense vascular paracrine signals and respond by secreting a variety of vasoactive adipocytokines. Due to the crucial role of PVAT in regulating many aspects of vascular biology, it may constitute a novel therapeutic target for the prevention and treatment of vascular disease pathogenesis. Signalling pathways in PVAT, such as those using adiponectin, H₂ S, glucagon-like peptide 1 or pro-inflammatory cytokines, are among the potential novel pharmacological therapeutic targets of PVAT.

LINKED ARTICLES

This article is part of a themed section on Molecular Mechanisms Regulating Perivascular Adipose Tissue - Potential Pharmacological Targets? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.20/issuetoc.

Review: Managing cardiovascular risk in patients with diabetes

The increasingly large number of patients with diabetes in the UK are at greatly increased risk of cardiovascular disease, including coronary heart disease and stroke, compared to the general population. Many diabetes patients exhibit metabolic syndrome and these additional risk factors, such as raised hypertension and cholesterol, multiply the overall risk. Reducing these risk factors to target levels is essential and requires a multifactorial approach. Lifestyle changes, tight glycaemic control, antiplatelet drugs (aspirin) and control of lipid levels, e.g. using statins, can all have significant beneficial effects. Blood pressure control is another vital aspect in reducing risk and a number of recent studies have provided evidence supporting the use of angiotensin-converting enzyme inhibitors as first-line treatment in patients with diabetes.

Dual renin-angiotensin-aldosterone blockade: promises and pitfalls

Single renin-angiotensin-aldosterone system (RAAS) blockade has been shown to be effective and safe for the treatment of hypertension, coronary heart disease (CHD), heart failure (HF), diabetes, and chronic kidney disease (CKD) with proteinuria. Due to the action of RAAS blockers at various levels of the RAAS cascade, it was hypothesized that dual RAAS blockade would result in more complete inhibition of angiotensin II (Ang II) production and be more effective in blocking its detrimental cardiovascular remodeling effects. Unfortunately, several clinical trials in patients with hypertension, CHD, HF, and CKD with proteinuria have demonstrated no superiority of dual versus single RAAS blockade, but a higher incidence of adverse events. Based on these findings, dual RAAS blockade is no longer recommended for the routine treatment of various cardiovascular diseases, except diabetic nephropathy with proteinuria and HF with reduced ejection fraction. All the new information gathered from studies within the last 3 years will be presented in this review.

Emerging drugs for chronic kidney disease

INTRODUCTION

Chronic kidney disease (CKD) is a worldwide health problem. Despite remarkable headway in slowing the progression of kidney diseases, the incidence of end-stage renal disease (ESRD) is increasing in all countries with a severe impact on patients and society. The high incidence of diabetes and hypertension, along with the aging population, may partially explain this growth. Currently, the mainstay of pharmacological treatment for CKD, aiming to slow progression to ESRD are ACE inhibitors and angiotensin II receptor blockers for their hemodynamic/antihypertensive and anti-inflammatory/antifibrotic action. However, novel drugs would be highly desirable to effectively slow the progressive renal function loss.

AREAS COVERED

Through the search engines, PubMed and ClinicalTrial.gov, the scientific literature was reviewed in search of emerging drugs in Phase II or III trials, which appear to be the most promising for CKD treatment.

EXPERT OPINION

The great expectations for new drugs for the management of CKD over the last decade have unfortunately not been met. Encouraging results from preliminary studies with specific agents need to be tempered with caution, given the absence of consistent and adequate data. To date, several agents that showed great promise in animal studies have been less effective in humans.

Effects of Losartan-based therapy on the incidence of end-stage renal disease and associated costs in type 2 diabetes mellitus: A retrospective cost-effectiveness analysis in the United Kingdom

BACKGROUND

In the Reduction of Endpoints in Non-Insulin-Dependent Diabetes Mellitus with the Angiotensin II Antagonist Losartan (RENAAL) study, the primary composite end point was the 2-fold increase in baseline serum creatinine concentration, the development of end-stage renal disease (ESRD), or death. The effects of losartan used for the prevention or delay of progression of diabetic nephropathy to ESRD were compared with those of conventional anti-hypertensive treatment (control) (calcium channel blockers, diuretics, α-blockers, β-blockers, and centrally acting agents), but not angiotensin-converting enzyme (ACE) inhibitors or angiotensin II antagonists (AIIAs), in 1513 adults with type 2 diabetes mellitus (DM-2) and nephropathy. Both treatment groups received conventional antihypertensive therapy (calcium channel blockers, diuretics, α-blockers, β-blockers, and/or centrally acting agents). ACE inhibitors and AIIAs were not allowed during the study period. The relative risk (RR) for composite outcome was 25% less, and the RR for ESRD was 28% less, in the losartantreated group compared with the control group.

OBJECTIVE

The aim of this retrospective cost-effectiveness analysis was to use data from the RENAAL study to determine the survival benefits and lifetime direct medical costs of a losartan-based regimen for the prevention of ESRD in patients with DM-2 and nephropathy in the setting of the UK National Health Service (NHS).

METHODS

This analysis used life-years saved as the effectiveness measure. The effect of losartan-based treatment on ESRD risk was confined to the trial period (3.5 years). However, survival and the lifetime direct medical costs of managing ESRD were projected beyond the trial period to incorporate the full effects of ESRD on survival and resource use. The effect of altering key variables was examined using 1-way sensitivity analyses.

RESULTS

ESRD-related costs were significantly lower in patients receiving losartan-based treatment compared with those in the control group (savings per patient, 7390 [95% CI, 11,366-3414; P< 0.001] [1 = US -$1.75]). Incorporation of the cost of losartan into the assessment found reduced net costs (savings per patient, 6622 [95% CI, 10,591-2653; P= 0.001]). The projected mean number of life years saved due to ESRD risk reduction with losartan was 0.44 years (95% CI, 0.16-0.71; P = 0.002). Losartan treatment was found to save costs in all cases, even if the cost of renal replacement therapy for patients with ESRD was reduced by 50%.

CONCLUSION

In this retrospective cost-effectiveness analysis using data from the RENAAL study, losartan-based treatment for the prevention or delay of progression of diabetic nephropathy to ESRD in patients with DM-2 and nephropathy was found to be potentially cost saving compared with conventional anti-hypertensive therapy from the perspective of the UK NHS.

Definition, identification and treatment of resistant hypertension in chronic kidney disease patients

Resistant hypertension, the inability to achieve goal blood pressure despite the use of three or more appropriately dosed antihypertensive drugs (including a diuretic), remains a common clinical problem, especially in patients with chronic kidney disease (CKD). While the exact prevalence and prognosis of resistant hypertension in CKD patients remain unknown, resistant hypertension likely contributes significantly to increased cardiovascular risk and progression of kidney disease in this population. We review the identification and evaluation of patients with resistant hypertension, including the importance of 24-h ambulatory blood pressure monitoring in the identification of 'white-coat', 'masked' and 'non-dipper' hypertension, the latter of which has particular clinical and therapeutic importance in patients with resistant hypertension and CKD. We then discuss treatment strategies for resistant hypertension that target the pathophysiologic mechanisms underlying resistance to treatment, including persistent volume excess, incomplete renin-angiotensin-aldosterone system blockade and inadequate nocturnal blood pressure control. Finally, we propose a treatment algorithm for evaluation and treatment of resistant hypertension in patients with CKD.

Renin inhibitors and cardiovascular and renal protection: an endless quest?

Renin-angiotensin system (RAS) blockade with angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) has become a major therapeutic approach in medicine since the end of the 1970's. Although these molecules were the first RAS blockers to be developed, it would have been physiologically and pharmacologically more pertinent to selectively inhibit renin itself. Indeed, the reaction between renin and its unique substrate, angiotensinogen, is the highly regulated and rate-limiting step of the RAS. The development of direct renin inhibitors (DRI) has been a slow and complex process and the synthesis of the first orally active DRI, aliskiren, was only achieved in the 2000's. Its pharmacological profile in patients with hypertension, diabetic nephropathy or heart failure, in addition to experimental evidence, suggests that aliskiren may be of value for the management of cardiovascular and renal diseases. However, the long-term, randomized, placebo-controlled, morbidity/mortality trial, ALTITUDE, which included 8,600 patients with type 2 diabetes, proteinuria and a high cardiovascular risk already treated with ACE inhibitors or ARBs was terminated in December 2011 because of futility and an increased incidence of serious adverse events in the aliskiren 300 mg arm. Other long-term studies are still ongoing to demonstrate the safety and efficacy of aliskiren to reduce cardiovascular morbidity and mortality in patients with heart failure and in elderly individuals (≥65 years) with systolic blood pressure of 130 to 159 mmHg, no overt cardiovascular disease, and a high cardiovascular risk profile. In the meantime, according to the European Medicines Agency recommendations, aliskiren should not be prescribed to diabetic patients in combination with ACE inhibitors or ARBs.

Dual renin-angiotensin system inhibition for prevention of renal and cardiovascular events: do the latest trials challenge existing evidence?

Circulatory and tissue renin-angiotensin systems (RAS) play a central role in cardiovascular (CV) and renal pathophysiology, making RAS inhibition a logical therapeutic approach in the prevention of CV and renal disease in patients with hypertension. The cardio- and renoprotective effects observed with angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARBs) monotherapy, together with the availability of a direct renin inhibitor (DRI), led to the investigation of the potential benefits of dual RAS inhibition. In small studies, ARB and ACE inhibitor combinations were shown to be beneficial in patients with CV or renal disease, with improvement in surrogate markers. However, in larger outcome trials, involving combinations of ACE inhibitors, ARBs or DRIs, dual RAS inhibition did not show reduction in mortality in patients with diabetes, heart failure, coronary heart disease or after myocardial infarction, and was in fact, associated with increased harm. A recent meta-analysis of all major trials conducted over the past 22 years involving dual RAS inhibition has clearly shown that the risk-benefit ratio argues against the use of dual RAS inhibition. Hence, the recent evidence clearly advocates against the use of dual RAS inhibition, and single RAS inhibition appears to be the most suitable approach to controlling blood pressure and improving patient outcomes.

Effectiveness and safety of dual renin-angiotensin system blockade: a comparison between younger and older cohorts

OBJECTIVE

The purpose of this review was to evaluate blood pressure (BP) reductions and adverse events between patients younger than 65 and older than 65 years of age receiving a combination of an angiotensin converting enzyme inhibitor (ACE-I) and an angiotensin receptor blocker (ARB).

DESIGN

A retrospective cohort study comparing the effectiveness of ACE-I and ARB combination in patients < 65 (younger) and ≥ 65 years of age (elderly).

SETTING

This study was conducted at the VA Western New York Healthcare System.

PARTICIPANTS

A total of 176 patients: 54 patients in the younger group and 122 in the elderly cohort.

INTERVENTIONS

No specific interventions were performed.

MAIN OUTCOME MEASURES

The purpose was to evaluate differences in BP reductions and incidence of adverse events in younger and elderly patients receiving a combination of an ACE-I and an ARB.

RESULTS

In the elderly group (mean age 76), the mean reduction in standing blood pressure (SBP) was 14.2 ± 15.6 mmHg (95% confidence interval [CI] 11.2-17.3; P < 0.0001). Similar results were obtained in the younger group (mean age 59), with a mean SBP reduction of 10 ± 14.9 (95% CI 5.6-14.5; P < 0.0001). The mean SBP reduction was not significantly different between the two age cohorts (P = 0.57). The incidence of adverse events was not different between the two age groups (cough P = 0.67, hyperkalemia P = 1.0, angioedema P = 0.31).

CONCLUSION

There was no significant difference in effectiveness or safety between the elderly and younger cohorts. The pharmacist monitoring elderly patients on combination therapy should still closely follow these patients; however it is reassuring that elderly patients do not experience adverse reactions at rates higher than do younger patients.

Is there benefit in dual renin-angiotensin-aldosterone system blockade? No, yes and maybe: a guide for the perplexed

Since the initial discovery of Angiotensin converting enzyme inhibitors (ACEI) in the 1960s and the launch of Captopril as the first available for clinical use in the 1970s, there now exist three other classes of drugs that block the renin angiotensin aldosterone system (RAAS): the angiotensin II receptor blockers (ARB), aldosterone antagonists (AA) and direct renin inhibitors (DRI). With the proven efficacy of RAAS blockers as monotherapy in many arenas there has been considerable interest in the use of dual therapy combinations of these medications that target different points in the pathway. By potentially offering a more complete RAAS blockade with a commensurate enhanced clinical effect, the strong biological rationale for dual therapy has led to it being embraced by clinicians as a treatment option, for hypertension and nephroprotection in particular. However, the initial enthusiasm for this treatment has been tempered by the recent results from several large trials such as ONTARGET and ALTITUDE, which do not support a specific dual therapy approach. In contrast, there is supportive evidence for dual blockade of specific combinations in selected patient groups and data are lacking for others. In the wake of this complex contemporary evidence, the conundrum now faced by clinicians committed to individualised care is, for which patients dual therapy could still be of benefit. This review examines for the practising clinician the current 'state of play' for dual blockade of various combinations and a perspective on its use in cardio-renal disease and diabetic complications.

To RAS or not to RAS? The evidence for and cautions with renin-angiotensin system inhibition in patients with diabetic kidney disease

Substantial morbidity, mortality, and costs are associated with progressive diabetic kidney disease (DKD). A goal of Healthy People 2020 is to reduce kidney disease attributable to diabetes mellitus and increase the proportion of patients who receive agents that interrupt the renin-angiotensin system (RAS), such as angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs). The mechanisms that contribute to progressive loss of kidney function in patients with diabetes are disrupted by inhibition of the RAS. ACEIs, ARBs and direct renin inhibitors (DRIs) all reduce the effect of angiotensin II, yet each works through a different mechanism and displays properties that may or may not be replicated by the others. As single agents, RAS inhibitors and blockers have been shown to slow the rate of progression of DKD and to reduce new cases of end-stage renal disease in various subsets of patients with diabetes and proteinuria (e.g., albuminuria). However, even with contemporary use of ACEIs, ARBs, and, more recently, DRIs, the burden of kidney disease remains high. Thus investigators sought to explore the utility of combining agents (e.g., dual RAS therapy) in various regimens for cardiovascular and kidney end points. Recent data from the Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial (ONTARGET) and Aliskiren Trial in Type 2 Diabetes Using Cardio-Renal Endpoints (ALTITUDE) studies suggest that kidney-related outcomes (composite of dialysis initiation, doubling serum creatinine concentration, or death) were increased with ACEI plus ARB or DRI plus ARB combinations. Consequently, dual therapy should not be routinely prescribed in patients with diabetes until further data become available from other future studies. This review provides an introduction to DKD and a rationale for using RAS inhibition; discusses screening, detection, and monitoring of patients with DKD; and summarizes results from meta-analyses and critical reviews and from recent large randomized controlled studies published since the meta-analyses or reviews. Finally, we suggest a clinical approach for using RAS agents in patients with DKD.

Living high training low induces physiological cardiac hypertrophy accompanied by down-regulation and redistribution of the renin-angiotensin system

AIM

Living high training low" (LHTL) is an exercise-training protocol that refers living in hypoxia stress and training at normal level of O2. In this study, we investigated whether LHTL caused physiological heart hypertrophy accompanied by changes of biomarkers in renin-angiotensin system in rats.

METHODS

Adult male SD rats were randomly assigned into 4 groups, and trained on living low-sedentary (LLS, control), living low-training low (LLTL), living high-sedentary (LHS) and living high-training low (LHTL) protocols, respectively, for 4 weeks. Hematological parameters, hemodynamic measurement, heart hypertrophy and plasma angiotensin II (Ang II) level of the rats were measured. The gene and protein expression of angiotensin-converting enzyme (ACE), angiotensinogen (AGT) and angiotensin II receptor I (AT1) in heart tissue was assessed using RT-PCR and immunohistochemistry, respectively.

RESULTS

LLTL, LHS and LHTL significantly improved cardiac function, increased hemoglobin concentration and RBC. At the molecular level, LLTL, LHS and LHTL significantly decreased the expression of ACE, AGT and AT1 genes, but increased the expression of ACE and AT1 proteins in heart tissue. Moreover, ACE and AT1 protein expression was significantly increased in the endocardium, but unchanged in the epicardium.

CONCLUSION

LHTL training protocol suppresses ACE, AGT and AT1 gene expression in heart tissue, but increases ACE and AT1 protein expression specifically in the endocardium, suggesting that the physiological heart hypertrophy induced by LHTL is regulated by region-specific expression of renin-angiotensin system components.

Sequential nephron blockade versus sequential renin-angiotensin system blockade in resistant hypertension: a prospective, randomized, open blinded endpoint study

OBJECTIVE

To compare two drug regimens to treat resistant hypertension.

METHODS

In a prospective, randomized, open blinded endpoint study, 167 patients with mean baseline daytime ambulatory blood pressure 135 mmHg or more and/or 85 mmHg or more, despite 4 weeks' treatment with irbesartan 300 mg/day, hydrochlorothiazide 12.5 mg/day and amlodipine 5 mg/day, were randomized to sequential nephron blockade (group 1, n = 85) or sequential renin-angiotensin system blockade (group 2, n = 82). First, spironolactone 25 mg/day in group 1 or ramipril 5 mg/day in group 2 were added for 4 weeks. Treatment was increased at weeks 4, 8 or 10 if home blood pressure was 135 mmHg or more and/or 85 mmHg or more by sequentially administering furosemide 20 mg/day, furosemide 40 mg/day and amiloride 5 mg/day in group 1, or ramipril 10 mg/day, bisoprolol 5 mg/day and bisoprolol 10 mg/day in group 2. The primary endpoint was change in systolic daytime ambulatory blood pressure at week 12.

RESULTS

At week 12, the mean between-group difference in daytime ambulatory blood pressure was 10/4 mmHg (95% confidence interval: 7-14/2-7; P < 0.001/P = 0.0014) in favour of the group 1. The blood pressure goal (daytime ambulatory blood pressure <135/85 mmHg) was achieved in 58% in the group 1 and 20% in the group 2 (P < 0.0001). Discontinuation for drug-related adverse events was low (group 1, n = 7; group 2, n = 6).

CONCLUSION

In patients with resistant hypertension, sequential nephron blockade induces a large and well tolerated reduction in blood pressure via a progressive increase in sodium depletion, and is more effective than sequential renin-angiotensin system blockade.

Strategies for combination therapy in hypertension

PURPOSE OF REVIEW

To achieve the target blood pressure (BP) mandated by current guidelines, a large majority of patients require simultaneous administration of multiple antihypertensive agents. The purpose of this review is to focus attention on the rational selection of effective drug combinations, and upon ways to use them efficiently to achieve therapeutic objectives. The topic is widely relevant given that more than 46  million ambulatory care visits are conducted in the United States annually for hypertension management.

RECENT FINDINGS

Recommended drug combinations exhibit complimentary pharmacology and additive BP reduction, are well tolerated, and include components with demonstrated endpoint reduction in long-term clinical trials. Recently, the choice of diuretics has emerged as a controversial issue with some evidence favoring the long-acting agent, chlorthalidone, in preference to hydrochlorothiazide. For resistant hypertension, mineralocorticoid antagonists are increasingly used as preferred add-on agents. Practical strategies for the optimal use of combination therapy continue to evolve from the older stepped-care approach to the use of low-dose combinations, and to initiation of combination therapy in a broader range of hypertensive patients.

SUMMARY

Thoughtful use of drug combinations is critical for achieving therapeutic objectives in hypertensive individuals and populations - more rapid BP control and more effective endpoint reduction. Practical strategies for the optimal use of combination therapy continue to evolve from the older stepped-care approach to more recent recommendations favoring the use of low-dose combinations, and initiation therapy of combination treatment, particularly in patients with Stage 2 hypertension.

Dynamic changes in the secondary structure of ECE-1 and XCE account for their different substrate specificities

Background

X-converting enzyme (XCE) involved in nervous control of respiration, is a member of the M13 family of zinc peptidases, for which no natural substrate has been identified yet. In contrast, it’s well characterized homologue endothelin-converting enzyme-1 (ECE-1) showed broad substrate specificity and acts as endopeptidase as well as dipeptidase. To explore the structural differences between XCE and ECE-1, homology model of XCE was built using the complex structure of ECE-1 with phosphoramidon (pdb-id: 3DWB) as template. Phosphoramidon was docked into the binding site of XCE whereas phosphate oxygen of the inhibitor was used as water molecule to design the apo forms of both enzymes. Molecular dynamics simulation of both enzymes was performed to analyze the dynamic nature of their active site residues in the absence and presence of the inhibitor.

Results

Homology model of XCE explained the role of non-conserved residues of its S2’ subsite. Molecular dynamics (MD) simulations identified the flexible transitions of F149/I150, N566/N571, W714/W719, and R145/R723 residues of ECE-1/XCE for the strong binding of the inhibitor. Secondary structure calculations using DSSP method reveals the folding of R145/R723 residue of ECE-1/XCE into β-sheet structure while unfolding of the S2’ subsite residues in aECE-1 and sustained compact folding of that of aXCE. The results evaluated are in good agreement with available experimental data, thus providing detailed molecular models which can explain the structural and specificities differences between both zinc peptidases.

Conclusions

Secondary structure changes of both enzymes during the simulation time revealed the importance of β-sheet structure of R145/R723 for its binding with the terminal carboxylate group of the inhibitor. Unfolding of the α-helix comprising the S2’ subsite residues in aECE-1 correlate well with its endopeptidase activity while their compact folding in aXCE may account for the inactivity of the enzyme towards large C-terminal containing substrates.

Educational paper: Progression in chronic kidney disease and prevention strategies

Chronic kidney disease (CKD) in children is a rare but devastating condition. Once a critical amount of nephron mass has been lost, progression of CKD is irreversible and results in end-stage renal disease (ESRD) and need of renal replacement therapy. The time course of childhood CKD is highly variable. While in children suffering from congenital anomalies of the kidneys and the urinary tract, progression of CKD in general is slow, in children with acquired glomerulopathies, disease progression can be accelerated resulting in ESRD within months. However, irrespective of the underlying kidney disease, hypertension and proteinuria are independent risk factors for progression. Thus, in order to prevent progression, the primary objective of treatment should always aim for efficient control of blood pressure and reduction of urinary protein excretion. Blockade of the renin-angiotensin-aldosterone system preserves kidney function not only by lowering blood pressure, but also by reducing proteinuria and exerting additional anti-proteinuric, anti-fibrotic, and anti-inflammatory effects. Besides, intensified blood pressure control, aiming for a target blood pressure below the 50th percentile, may exert additive renoprotective effects. Additionally, other modifiable risk factors, such as anemia, metabolic acidosis, dyslipidemia, and altered bone-mineral homeostasis may also contribute to CKD progression. In conclusion, beyond strict blood pressure control and reduction of urinary protein excretion, identification and treatment of both, renal disease-related and conventional risk factors are mandatory in children with CKD in order to prevent deterioration of kidney function.

Comparison of the effects of aliskiren/valsartan in combination versus valsartan alone in patients with stage 2 hypertension

The extent to which the combination of a renin inhibitor with an angiotensin receptor blocker (ARB) lowers clinic and ambulatory blood pressure (BP) versus an ARB alone in stage 2 hypertension is not well known. Hence, we performed an 8-week, randomized, double-blind study in 451 patients with stage 2 hypertension to compare the efficacy of the combination of aliskiren/valsartan 300/320 mg versus valsartan 320 mg. The primary endpoint was change in seated systolic BP from baseline to week 8 analyzed on the intent-to-treat (ITT) population using the last-observation-carried-forward (LOCF) approach; patients completing the entire treatment period (per-protocol completers) were similarly analyzed. For the predefined primary analysis, systolic BP reductions for aliskiren/valsartan (n = 230) and valsartan (n = 217) were -22.1 and -20.5 mm Hg, respectively (P = .295). In per-protocol completers, aliskiren/valsartan (n = 201) lowered BP significantly greater than valsartan (n = 196); -23.7 mm Hg versus -20.3 mm Hg, respectively (P = .028). Although limited by a small sample size (n = 76) using ambulatory BP monitoring, aliskiren/valsartan lowered the 24-hour BP significantly more than valsartan alone (-14.6/-9.0 mm Hg versus -5.9/-4.2 mm Hg; P < .01). Safety and tolerability were similar for the two treatment groups. These data demonstrate the importance of multiple modalities to assess BP changes in clinical trials of antihypertensive therapies, particularly in stage 2 hypertension.

What is the role of direct renin inhibitors in the treatment of the hypertensive diabetic patient?

The renin-angiotensin system (RAS) is the most important mechanism leading to cardiovascular and renal damage in diabetic patients. Studies conducted until now have unequivocally demonstrated that antihypertensive treatment with RAS blockers (angiotensin-converting enzyme (ACE) inhibitors or angiotensin-receptor blockers) improve the prognosis of patients with diabetes, by reducing rates of cardiovascular events and preventing or delaying the progression of diabetic nephropathy. However, despite the benefits of such treatment, cardio-renal events are still very frequent in diabetics. Several strategies for reducing this cardiovascular and renal risk have been proposed, but among them, a more complete blockade of the RAS seems the most attractive. Direct renin inhibitors are RAS blockers with some particularities, such as their ability to reduce plasma renin activity or the possibility to modulate tissue and intracellular RAS, which could represent a theoretical advantage when treating diabetic patients. In experimental and clinical studies conducted until now, aliskiren is able to reduce blood pressure in diabetics, alone or in combination with ACE inhibitors or angiotensin-receptor blockers. Moreover, aliskiren reduces markers of cardiac and renal disease, such as left ventricular hypertrophy or post-infarction ventricular remodeling, as well as proteinuria in diabetics already treated with other RAS blockers. The translation of these promising results to the clinical arena is currently being investigated in the Aliskiren Trial in Type 2 Diabetes Using Cardio-Renal Endpoints (ALTITUDE), where more than 8600 diabetic patients with chronic kidney disease and at high-risk of cardio-renal events are treated with aliskiren or placebo added to the current treatment consisting of another RAS blocker. If positive, aliskiren will be the treatment of choice in the prevention of cardiorenal disease in diabetics.

Rationale for combining a direct renin inhibitor with other renin- angiotensin system blockers. Focus on aliskiren and combinations

Inhibition of the renin-angiotensin system has been a highly successful therapeutic approach for the prevention of hypertension-related end organ damage. Angiotensin converting enzyme inhibitors and angiotensin II receptor blockers lower blood pressure and reduce morbidity and mortality in patients with cardiovascular and kidney disease. However, progression to end-stage disease remains common in these patient populations. A compensatory increase in plasma renin activity occurs with the use of either angiotensin converting enzyme inhibitors or angiotensin II receptor blockers, thus causing increased levels of angiotensin II, which may limit the therapeutic effectiveness of these agents. The direct renin inhibitor, aliskiren, suppresses the renin-angiotensin system by inhibiting its first and rate-limiting step. This early inhibition reduces the production of all downstream components of the system. In this review, recent clinically relevant advances in the understanding of renin-angiotensin system biology are explored as a rationale for combining aliskiren with other blockers of the renin-angiotensin system. These combinations more fully inhibit the renin-angiotensin system, with the goal of providing additional therapeutic benefits in diseases associated with chronic activation of the renin-angiotensin system.

Characterization of the genomic structure and function of regions influencing renin and angiogenesis in the SS rat

Impaired regulation of renin in Dahl salt-sensitive rats (SS/JRHsdMcwi, SS) contributes to attenuated angiogenesis in this strain. This study examined angiogenic function and genomic structure of regions surrounding the renin gene using subcongenic strains of the SS and BN/NHsdMcwi (BN) rat to identify important genomic variations between SS and BN involved in angiogenesis. Three candidate regions on Chr 13 were studied: two congenic strains containing 0.89 and 2.62 Mb portions of BN Chr 13 that excluded the BN renin allele and a third strain that contained a 2.02 Mb overlapping region that included the BN renin allele. Angiogenesis induced by electrical stimulation of the tibialis anterior muscle was attenuated in the SS compared with the BN. Congenics carrying the SS renin allele had impaired angiogenesis, while strains carrying the BN renin allele had angiogenesis restored. The exception was a congenic including a region of BN genome 0.4 Mb distal to renin that restored both renin regulation and angiogenesis. This suggests that there is a distant regulatory element in the BN capable of restoring normal regulation of the SS renin allele. The importance of ANG II in the restored angiogenic response was demonstrated by blocking with losartan. Sequencing of the 4.05 Mb candidate region in SS and BN revealed a total of 8,850 SNPs and other sequence variants. An analysis of the genes and their variants in the region suggested a number of pathways that may explain the impaired regulation of renin and angiogenesis in the SS rat.

Albuminuria: is it time to screen the general population?

Albuminuria has been associated with increased risk of multiple adverse outcomes, including ESRD, acute kidney injury, cardiovascular disease, and death. Some clinicians advocate for population-based screening of this condition, as a means of identifying individuals at high risk for morbidity and mortality. Several factors influence the potential implementation of screening for albuminuria in the general population, including the type of test used, the threshold for albuminuria, the validity and prognostic value of testing, frequency of follow-up testing, and associated costs of screening. This review discusses the available literature addressing these issues, and suggests an approach to screening patients for albuminuria.

Renin-angiotensin-aldosterone blockade for cardiovascular disease prevention

The renin-angiotensin-aldosterone system (RAAS) plays a significant role in pathophysiology of multiple disease states. RAAS blockade is beneficial in patients with hypertension, acute myocardial infarction, chronic heart failure, stroke, and diabetic renal disease. RAAS blockade with the combination angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) has demonstrated conflicting results in recent clinical trials. This article reviews the latest evidence of isolated ACEI or ARB use, their combination, and the role of aldosterone blockers and direct renin inhibitors in patients at risk, and makes recommendations for their use in the prevention of morbidity and mortality in cardiovascular disease.

Renin Angiotensin Aldosterone System Blockade: Little to No Rationale for ACE Inhibitor and ARB Combinations

Our understanding of the complexities and inter-related pathways of the renin-angiotensin-aldosterone system continues to evolve. Which drugs to use, when, and how, are everyday questions faced by clinicians in the ambulatory setting. Combining these classes, for the purpose of enhancing renin-angiotensin-aldosterone system blockade and incremental blood pressure, nephroprotective, and cardioprotective effects, logically has emerged as an area for scientific inquiry and clinical use. Despite the lack of evidence on safety and efficacy in most disease states, dual therapy has been embraced as a treatment option. Most studies of angiotensin-converting enzyme (ACE) inhibitor and angiotensin receptor blocker (ARB) combination therapy in the treatment of hypertension have limitations. In contrast, combination ACE inhibitor-ARB therapy in systolic heart failure has been addressed in several large randomized controlled trials. Until recently, there has been limited and conflicting evidence for the use of combination therapy for the prevention or management of nephropathy. Based on the new evidence, combination ACE inhibitor-ARB therapy in the treatment and management of hypertension, heart failure, and nephropathy should be limited.