Addition of an angiotensin receptor blocker to full-dose ACE-inhibition: controversial or common sense?

Lessons learned from early-stage clinical trials for diabetic nephropathy

INTRODUCTION

The evolution of treatment for diabetic nephropathy illustrates how basic biochemistry and physiology have led to new agents such as SGLT2 inhibitors and mineralocorticoid blockers. Conversely, clinical studies performed with these agents have suggested new concepts for investigational drug development. We reviewed currently available treatments for diabetic nephropathy and then analyzed early clinical trials of new agents to assess the potential for future treatment modalities.

AREAS COVERED

We searched ClinicalTrials.gov for new agents under study for diabetic nephropathy in the past decade. Once we have identified investigation trials of new agents, we then used search engines and Pubmed.gov to find publications providing insight on these drugs. Current treatments have shown benefit in both cardiac and renal disease. In our review, we found 51 trials and 43 pharmaceuticals in a number of drug classes: mineralocorticoid blockers, anti-inflammatory, anti-fibrosis, nitric oxide stimulatory, and podocyte protection, and endothelin inhibitors.

EXPERT OPINION

It is difficult to predict which early phase treatments will advance to confirmatory clinical trials. Current agents are thought to improve hemodynamic function. However, the coincident benefit of both myocardial function and the glomerulus argues for primary effects at the subcellular level, and we follow the evolution of agents which modify fundamental cellular processes.

Cardiac hypertrophy in mice submitted to a swimming protocol: influence of training volume and intensity on myocardial renin-angiotensin system

Exercise promotes physiological cardiac hypertrophy and activates the renin-angiotensin system (RAS), which plays an important role in cardiac physiology, both through the classical axis [angiotensin II type 1 receptor (AT1R) activated by angiotensin II (ANG II)] and the alternative axis [proto-oncogene Mas receptor (MASR) activated by angiotensin-(1–7)]. However, very intense exercise could have deleterious effects on the cardiovascular system. We aimed to analyze the cardiac hypertrophy phenotype and the classical and alternative RAS axes in the myocardium of mice submitted to swimming exercises of varying volume and intensity for the development of cardiac hypertrophy. Male Balb/c mice were divided into three groups, sedentary, swimming twice a day without overload (T2), and swimming three times a day with a 2% body weight overload (T3), totaling 6 wk of training. Both training groups developed similar cardiac hypertrophy, but only T3 mice improved their oxidative capacity. We observed that T2 had increased levels of MASR, which was followed by the activation of its main downstream protein AKT; meanwhile, AT1R and its main downstream protein ERK remained unchanged. Furthermore, no change was observed regarding the levels of angiotensin peptides, in either group. In addition, we observed no change in the ratio of expression of the myosin heavy chain β-isoform to that of the α-isoform. Fibrosis was not observed in any of the groups. In conclusion, our results suggest that increasing exercise volume and intensity did not induce a pathological hypertrophy phenotype, but instead improved the oxidative capacity, and this process might have the participation of the RAS alternative axis.

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.

Angiotensin-(1-7) counteracts angiotensin II-induced dysfunction in cerebral endothelial cells via modulating Nox2/ROS and PI3K/NO pathways

Angiotensin (Ang) II, the main effector of the renin-angiotensin system, has been implicated in the pathogenesis of vascular diseases. Ang-(1-7) binds to the G protein-coupled Mas receptor (MasR) and can exert vasoprotective effects. We investigated the effects and underlying mechanisms of Ang-(1-7) on Ang II-induced dysfunction and oxidative stress in human brain microvascular endothelial cells (HbmECs). The pro-apoptotic activity, reactive oxygen species (ROS) and nitric oxide (NO) productions in HbmECs were measured. The protein expressions of nicotinamide adenine dinucleotide phosphate oxidase 2 (Nox2), serine/threonine kinase (Akt), endothelial nitric oxide synthase (eNOS) and their phosphorylated forms (p-Akt and p-eNOS) were examined by western blot. MasR antagonist and phosphatidylinositol-3-kinase (PI3K) inhibitor were used for receptor/pathway verification. We found that Ang-(1-7) suppressed Ang II-induced pro-apoptotic activity, ROS over-production and NO reduction in HbmECs, which were abolished by MasR antagonist. In addition, Ang-(1-7) down-regulated the expression of Nox2, and up-regulated the ratios of p-Akt/Akt and its downstream p-eNOS/eNOS in HbmECs. Exposure to PI3K inhibitor partially abrogated Ang-(1-7)-mediated protective effects in HbmECs. Our data suggests that Ang-(1-7)/MasR axis protects HbmECs from Ang II-induced dysfunction and oxidative stress via inhibition of Nox2/ROS and activation of PI3K/NO pathways.

RU28318, an aldosterone antagonist, in combination with an ACE inhibitor and angiotensin receptor blocker attenuates cardiac dysfunction in diabetes

AIMS

We evaluated the effects of RU28318 (RU), a selective mineralocorticoid receptor (MR) antagonist, Captopril (Capt), an angiotensin converting enzyme inhibitor, and Losartan (Los), an angiotensin receptor blocker, alone or in combination with ischemia/reperfusion- (I/R-) induced cardiac dysfunction in hearts obtained from normal and diabetic rats.

METHODS

Isolated hearts were perfused for 30 min and then subjected to 30 min of global ischemia (I) followed by a period of 30 min of reperfusion (R). Drugs were administered for 30 min either before or after ischemia. Drug regimens tested were RU, Capt, Los, RU + Capt, RU + Los, Capt + Los, and RU + Capt + Los (Triple). Recovery of cardiac hemodynamics was evaluated.

RESULTS

Recovery of cardiac function was up to 5-fold worse in hearts obtained from diabetic animals compared to controls. Treatment with RU was generally better in preventing or reversing ischemia-induced cardiac dysfunction in normal hearts compared to treatment with Capt or Los alone. In diabetic hearts, RU was generally similarly effective as Capt or Los treatment.

CONCLUSIONS

RU treatment locally might be considered as an effective therapy or preventative measure in cardiac I/R injury. Importantly, RU was the most effective at improving -dP/dt (a measure of diastolic function) when administered to diabetic hearts after ischemia.

Blocking the RAAS at different levels: an update on the use of the direct renin inhibitors alone and in combination

The renin–angiotensin–aldosterone system (RAAS), an important regulator of blood pressure and mediator of hypertension-related complications, is a prime target for cardiovascular drug therapy. Angiotensin-converting enzyme inhibitors (ACEIs) were the first drugs to be used to block the RAAS. Angiotensin II receptor blockers (ARBs) have also been shown to be equally effective for treatment. Although these drugs are highly effective and are widely used in the management of hypertension, current treatment regimens with ACEIs and ARBs are unable to completely suppress the RAAS. Combinations of ACEIs and ARBs have been shown to be superior than to either agent alone for some, but certainly not all, composite cardiovascular and kidney outcomes, but dual RAAS blockade with the combination of an ACEI and an ARB is sometimes associated with an increase in the risk for adverse events, primarily hyperkalemia and worsening renal function. The recent introduction of the direct renin inhibitor, aliskiren, has made available new combination strategies to obtain a more complete blockade of the RAAS with fewer adverse events. Renin system blockade with aliskiren and another RAAS agent has been, and still is, the subject of many large-scale clinical trials and furthermore, is already available in some countries as a fixed combination.

Addressing the theoretical and clinical advantages of combination therapy with inhibitors of the renin-angiotensin-aldosterone system: antihypertensive effects and benefits beyond BP control

AIMS

This article reviews the importance of the renin-angiotensin-aldosterone system (RAAS) in the cardiometabolic continuum; presents the pros and cons of dual RAAS blockade with angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs); and examines the theoretical and practical benefits supporting the use of direct renin inhibitors (DRIs) in combination with ACEIs or ARBs.

MAIN METHODS

The author reviewed the literature for key publications related to the biochemical physiology of the RAAS and the pharmacodynamic effects of ACEIs, ARBs, and DRIs, with a particular focus on dual RAAS blockade with these drug classes.

KEY FINDINGS

Although ACEI/ARB combination therapy produces modest improvement in BP, it has not resulted in the major improvements predicted given the importance of the RAAS across the cardiorenal disease continuum. This may reflect the fact that RAAS blockade with ACEIs and/or ARBs leads to exacerbated renin release through loss of negative-feedback inhibition, as well as ACE/aldosterone escape through RAAS and non-RAAS-mediated mechanisms. Plasma renin activity (PRA) is an independent predictor of morbidity and mortality, even for patients receiving ACEIs and ARBs. When used alone or in combination with ACEIs and ARBs, the DRI aliskiren effectively reduces PRA. Reductions in BP are greater with these combinations, relative to the individual components alone.

SIGNIFICANCE

It is possible that aliskiren plus either an ACEI or ARB may provide greater RAAS blockade than monotherapy with ACEIs or ARBs, and lead to additive improvement in BP and clinically important outcomes.

Dual renin-angiotensin system blockade in the ONTARGET study: clinically relevant risk for the kidney?

Inhibition of the renin-angiotensin system contributes to reductions in proteinuria and in progression of chronic kidney disease. Indeed, monotherapy with either an angiotensin-converting enzyme (ACE) inhibitor or an angiotensin receptor blocker (ARB) has been shown to decrease proteinuria and slow the decline of chronic kidney disease, but incompletely. Therefore, there is increasing interest in whether combination strategies will provide more complete blockade of the renin-angiotensin system, which may translate into superior renoprotective and cardioprotective effects compared with either agent alone. There have been several reports on combination strategies. However, the recent report of the Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial (ONTARGET) has received much of the attention. The renal outcomes in ONTARGET suggest that combined ACE inhibitor and ARB therapy contributes to a higher rate of adverse renal outcomes than monotherapy. Therefore, this review explores data from ONTARGET in relation to other available evidence on the use of combination therapies.

Current possibilities of ACE inhibitor and ARB combination in arterial hypertension and its complications

The renin-angiotensin-aldosterone system (RAAS) plays a crucial role in blood pressure regulation and hypertension-related complications. Angiotensin-converting enzyme inhibitors (ACEIs) were the first to be used to block the RAAS and now have many compelling indications in the treatment of hypertension and its cardiovascular and renal complications. Angiotensin II receptor blockers (ARBs), introduced 20 years later, have been shown to be equally as effective as antihypertensive treatment and are also associated with a lower number of side effects. Furthermore, in clinical trials ARBs and ACEIs were associated with comparable benefits for their most typical indications. This was confirmed in the 2007 New European Society of Hypertension/European Society of Cardiology (ESH/ESC) guidelines for the management of hypertension by comparable specific recommendations for ARB and ACEI treatment. There is sufficient theoretical background and, in some cases, also clinical evidence that combination therapy with ACEIs and ARBs may be more beneficial than monotherapy with either of the groups alone, both in uncomplicated hypertension and with concomitant heart failure or renal dysfunction. However, the combination of ACEI and ARB was not recommended in the ESH/ESC 2007 Guidelines. This may change after the publication of the Ongoing Telmisartan Alone and in Combination with Ramipril Global End point Trial (ONTARGET) study, the preliminary results of which have just been presented. In heart failure, recent studies have shown that the combination of ACEI and ARB decreases cardiovascular mortality and the number of hospitalizations due to aggravation of heart failure. These results have been reflected in the newest ESC guidelines of the heart failure treatment. Nephroprotective properties of the combination of ACEs and ARBs have been proved both in studies on nondiabetic and diabetic nephropathy. The potential benefits, indications in prespecified groups of patients, the most recent data from clinical trials and latest research regarding dual blockade of RAAS will be reviewed in this article.

Effects of dual blockade of Renin-Angiotensin system on concentric left ventricular hypertrophy in essential hypertension: a randomized, controlled pilot study

BACKGROUND

The renin-angiotensin system (RAS) plays a major role in promoting left ventricular (LV) remodeling in essential hypertension. We designed a controlled, randomized pilot study aimed to test the hypothesis that the dual RAS blockade with angiotensin-converting enzyme (ACE) inhibitor (ACEi) + angiotensin II receptor blocker (ARB) can be more effective in decreasing LV hypertrophy and improving diastolic function than a largely employed association such as ACEi + calcium-antagonist (Ca-A).

METHODS

Twenty-four never-treated hypertensive patients with LV concentric hypertrophy were randomized to ramipril + candesartan or ramipril + lercanidipine. Before and after the 6-month treatment they underwent a 24-h blood pressure (BP) monitoring and echocardiographic examination.

RESULTS

At baseline, age, body mass index (BMI), 24-h BP, and LV morpho-functional parameters were similar between the two groups. The 6-month treatment induced in both groups a significant decrease of 24-h BP, septal and posterior wall thickness, and LV mass index (LVMi) (ACEi + ARB 155 +/- 19 to 122 +/- 17 g/m(2), P < 0.0001; ACEi + Ca-A 146 +/- 18 to 127 +/- 20 g/m(2), P < 0.0001). Systolic function remained unchanged; LV diastolic parameters increased significantly in both groups. The extent of 24-h BP decrease was similar between the two groups (-13.3/16.3% vs. -12.3/15.8%, P = 0.63/P = 0.71), whereas the decrease of LV mass (-22% vs. -12.8%, P < 0.005) and the improvement of diastolic function were greater in ACEi + ARB group.

CONCLUSIONS

In comparison with ACEi + Ca-A, ACEi + ARB treatment showed a greater antiremodeling effect, that can be reasonably ascribed to a BP-independent effect of the dual RAS blockade.

Reducing cardiovascular risk by blockade of the renin-angiotensin-aldosterone system

Many factors contribute to the overall risk of cardiovascular disease (CVD) in a given patient. Activation of the renin-angiotensin-aldosterone system (RAAS) is pivotal in the pathophysiology of CVD and renal disease and appears to place individuals at high risk for cardiovascular (CV) and renal events. Results from many large-scale, long-term clinical trials have demonstrated that RAAS blockade with an angiotensin-converting-enzyme inhibitor (ACEI) or an angiotensin receptor blocker (ARB) can significantly decrease CV and renal morbidity and mortality in a wide range of patients. Some of the clinical benefits derived from use of these agents appears to be independent of their ability to lower blood pressure. The combined use of an ACEI and an ARB for antihypertensive therapy has begun to receive considerable attention. Such an approach may seem counterintuitive, but ACEIs and ARBs have distinct and potentially complementary pharmacologic effects. Results from clinical trials thus far suggest that combination therapy with an ACEI plus an ARB may be a rational choice in patients with chronic activation of the RAAS, including those with heart failure or impaired left ventricular systolic function, diabetes, proteinuria, impaired renal function, recent myocardial infarction, or multiple CV risk factors. Results from ongoing, large-scale, clinical endpoint trials will provide important additional information about the benefits of dual RAAS inhibition in patients at high risk for CV morbidity and mortality.

Angiotensin converting enzyme inhibition in cardiovascular risk populations: a practical approach to identify the patient who will benefit most

PURPOSE OF REVIEW

Evidence from clinical trials suggests that angiotensin converting enzyme (ACE) inhibition has the broadest impact of any class of drugs in cardiovascular medicine, reducing cardiovascular morbidity and mortality. This beneficial effect varies across different patient populations, however. This review will summarize the current literature about the therapeutic potential of ACE inhibition and provide a practical approach for clinicians to identify patients who benefit most from ACE inhibition.

RECENT FINDINGS

ACE inhibition has been shown to benefit patients with heart failure, left ventricular dysfunction, postmyocardial infarction, nephropathy, peripheral vascular disease, diabetes, stroke or transient ischemic attack. The absolute clinical benefit varies across different risk populations, however, depending on the patient characteristics. ACE inhibitors are most effective in patients with an increased cardiovascular risk associated with an activated renin-angiotensin system and less effective in patients with classical cardiovascular risk factors, but without an activated renin-angiotensin system.

SUMMARY

We argue that markers of an activated renin-angiotensin system, such as left ventricular dysfunction, left ventricular hypertrophy, renal dysfunction, as assessed by estimated glomerular filtration rate, or urinary albumin excretion, may be used as targets and act as indicators for ACE-inhibition therapy and also for monitoring purposes. This will help clinicians to guide their therapy and identify patients who benefit most from ACE inhibition.

Combination ACE Inhibitor and Angiotensin Receptor Blocker Therapy-Future Considerations

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are regularly prescribed for the management of hypertension. Each of these drug classes has also been shown to provide survival benefits for patients with heart failure, proteinuric chronic kidney disease, and/or a high cardiac risk profile. The individual gains seen with each of these drug classes have led to speculation that their combination might offer additive if not synergistic outcome benefits. The foundation of this hypothesis, although biologically possible, has thus far not been sufficiently well proven to support the everyday use of these 2 drug classes in combination. Additional outcomes trials, which are currently proceeding to their conclusion, may provide the necessary proof to support an expanded use of these 2 drug classes in combination.