Aldosterone and aldosterone antagonism in cardiovascular disease: focus on eplerenone (Inspra)

Finerenone: a breakthrough mineralocorticoid receptor antagonist for heart failure, diabetes and chronic kidney disease

Background

Aldosterone is categorized as a mineralocorticoid hormone produced in the zona glomerulosa of the adrenal cortex. Aldosterone has considerable action in sodium and water retention along with cardiac remodeling, promoting fibrosis and these detrimental effects have been counteracted by mineralocorticoid receptors antagonists over time. Spironolactone, a non-selective steroidal MRA used extensively is potent but has serious adverse effects like gynecomastia and hyperkalemia. Eplerenone another second generation MRA, though non-steroidal and selective causes hyperkalemia and adversely effecting renal functions.

Main body

Recently Finerenone- a novel MRA has been introduced which is as potent like spironolactone with less adverse effects and improved cardiovascular outcomes particularly in chronic kidney failure with diabetes. The article reviews the physical and chemical properties of Finerenone and compares it with MRAs already in use, and then about the patient specific uses of Finerenone and future avenues of it. Finerenone is non-steroidal selective MRA, with promising results in improving the deterioration of renal functions in CKD with DM, reducing albuminuria with less hyperkalemia along with improvement in cardiovascular outcomes by reducing heart failure events.

Conclusion

Mineralocorticoid receptor antagonists have a proven role in preventing the adverse effects of RAAS pathway on heart, kidneys and blood vessels. Non-selective steroidal MRAs have potent action but by virtue of their non-selectivity associated with adverse effects like gynecomastia, hirsutism along with hyperkalemia Finerenone is novel non-steroidal & highly selective MRA, with promising results in halting the deterioration of renal functions in CKD with DM, reducing albuminuria, improvement in cardiovascular outcomes by reducing heart failure events albeit with less hyperkalemia. More randomized studies in dedicated HF patients are ongoing with Finerenone to prove it is worth in this sector with huge unmet need despite GDMT. Finerenone alleviates the risk of adverse renal and cardiac outcomes in patients with diabetes and CKD despite baseline medical therapy.

Mechanisms of current therapeutic strategies for heart failure: more questions than answers?

Heart failure (HF) is a complex, multifactorial and heterogeneous syndrome with substantial mortality and morbidity. Over the last few decades, numerous attempts have been made to develop targeted therapies that may attenuate the known pathophysiological pathways responsible for causing the progression of HF. However, therapies developed with this objective have sometimes failed to show benefit. The pathophysiological construct of HF with numerous aetiologies suggests that interventions with broad mechanisms of action which simultaneously target more than one pathway maybe more effective in improving the outcomes of patients with HF. Indeed, current therapeutics with clinical benefits in HF have targeted a wider range of intermediate phenotypes. Despite extensive scientific breakthroughs in HF research recently, questions persist regarding the ideal therapeutic targets which may help achieve maximum benefit. In this review, we evaluate the mechanism of action of current therapeutic strategies, the pathophysiological pathways they target and highlight remaining knowledge gaps regarding the mode of action of these interventions.

EET enhances renal function in obese mice resulting in restoration of HO-1-Mfn1/2 signaling, and decrease in hypertension through inhibition of sodium chloride co-transporter

BACKGROUND

We have previously reported that epoxyeicosatrienoic acid (EET) has multiple beneficial effects on renal and adipose tissue function, in addition to its vasodilatory action; it increases insulin sensitivity and inhibits inflammation. In an examination of the signaling mechanisms by which EET reduces renal and peri-renal fat function, we hypothesized that EET ameliorates obesity-induced renal dysfunction by improving sodium excretion, reducing the sodium-chloride cotransporter NCC, lowering blood pressure, and enhancing mitochondrial and thermogenic gene levels in PGC-1α dependent mice.

METHODS

EET-agonist treatment normalized glucose metabolism, renal ENaC and NCC protein expression, urinary sodium excretion and blood pressure in obese (db/db) mice. A marked improvement in mitochondrial integrity, thermogenic genes, and PGC-1α-HO-1-adiponectin signaling occurred. Knockout of PGC-1α in EET-treated mice resulted in a reversal of these beneficial effects including a decrease in sodium excretion, elevation of blood pressure and an increase in the pro-inflammatory adipokine nephroblastoma overexpressed gene (NOV). In the elucidation of the effects of EET on peri-renal adipose tissue, EET increased adiponectin, mitochondrial integrity, thermogenic genes and decreased NOV, i.e. "Browning' peri-renal adipose phenotype that occurs under high fat diets. Taken together, these data demonstrate a critical role of an EET agonist in the restoration of healthy adipose tissue with reduced release of inflammatory molecules, such as AngII and NOV, thereby preventing their detrimental impact on sodium absorption and NCC levels and the development of obesity-induced renal dysfunction.

Mineralocorticoid Receptor Antagonists for Treatment of Hypertension and Heart Failure

Spironolactone and eplerenone are both mineralocorticoid-receptor antagonists. These compounds block both the epithelial and nonepithelial actions of aldosterone, with the latter assuming increasing clinical relevance. Spironolactone and eplerenone both affect reductions in blood pressure either as mono- or add-on therapy; moreover, they each afford survival benefits in diverse circumstances of heart failure and the probability of renal protection in proteinuric chronic kidney disease. However, as use of mineralocorticoid-blocking agents has expanded, the hazards inherent in taking such drugs have become more apparent. Whereas the endocrine side effects of spironolactone are in most cases little more than a cosmetic annoyance, the potassium-sparing effects of both spironolactone and eplerenone can prove disastrous, even fatal, if sufficient degrees of hyperkalemia emerge. For most patients, however, the risk of developing hyperkalemia in and of itself should not discourage the sensible clinician from bringing these compounds into play. Hyperkalemia should always be considered a possibility in patients receiving either of these medications; therefore, anticipatory steps should be taken to minimize the likelihood of its occurrence if long-term therapy of these agents is being considered.

Review: Aldosterone — the future challenge in cardiovascular disease?

Mineralocorticoid receptor activation plays a key role in cardiovascular disease and hypertension, which are particularly prevalent in diabetes mellitus; secondary hyperaldosteronism contributes to cardiac failure. Major intervention trials in heart failure have demonstrated unequivocal benefit from aldosterone receptor antagonism. Focused experimental studies in humans and in animal models of hypertension have shown that aldosterone blockade improves a number of pathogenic abnormalities including vascular endothelial dysfunction and altered baroreflex function, and prevents the development of cardiac hypertrophy and renal histological damage. Based on recent outcomes studies, the challenge is now to transfer the experimental evidence into clinical M practice.

Proinflammatory protein CARD9 is essential for infiltration of monocytic fibroblast precursors and cardiac fibrosis caused by Angiotensin II infusion

Background

Angiotensin II (Ang II)–induced cardiac remodeling with the underlying mechanisms involving inflammation and fibrosis has been well documented. Cytosolic adaptor caspase recruitment domain 9 (CARD9) has been implicated in the innate immune response. We aimed to examine the role of CARD9 in inflammation and cardiac fibrosis induced by Ang II.

Methods

Two-month-old CARD9-deficient (CARD9^−/−) and wild-type (WT) male mice were infused with Ang II (1,500 ng/kg/min) or saline for 7 days. Heart sections were stained with hematoxylin and eosin and Masson trichrome and examined by immunohistochemistry; and activity and protein levels were measured in macrophages obtained from mice.

Results

WT mice with Ang II infusion showed a marked increase in CARD9⁺ macrophages in the heart, but CARD9^−/− mice showed significantly suppressed macrophage infiltration and expression of proinflammatory cytokines, including interleukin-1β (IL-1β) and connective tissue growth factor (CTGF). Importantly, Ang II–induced cardiac fibrosis (extracellular matrix and collagen I deposition) was diminished in CARD9^−/− hearts, as was the expression of transforming growth factor-β (TGF-β) and level of myofibroblasts positive for α-smooth muscle actin (α-SMA). Furthermore, Ang II activation of nuclear factor-κB (NF-κB), JNK and p38 mitogen-activated protein kinases (MAPKs) in WT macrophages was reduced in CARD9^−/− macrophages.

Conclusion

CARD9 plays an important role in regulating cardiac inflammation and fibrosis in response to elevated Ang II.

Use of diuretics in the treatment of heart failure in the elderly

Diuretics are tools of considerable therapeutic importance. First, they effectively reduce blood pressure, while at the same time decreasing the morbidity and mortality associated with hypertension. Diuretics are currently recommended as first-line therapy for the treatment of hypertension. In addition, they remain an important component of heart failure therapy, in that they improve the symptoms of congestion, which typify the more advanced stages of heart failure. This article reviews the mode of action of the various diuretic classes and the physiologic adaptations that follow; sets up the basis for their use in the treatment of volume-retaining states, particularly as applies to the elderly; and reviews diuretic-related side effects that are normally encountered.

NF-kappaB-dependent transcriptional regulation of the cardiac scn5a sodium channel by angiotensin II

Angiotensin II (ANG II) increases oxidative stress and is associated with increased risk of sudden cardiac death. The cardiac Na(+) channel promoter contains elements that confer redox sensitivity. We tested the hypothesis that ANG II-mediated oxidative stress may modulate Na(+) channel current through altering channel transcription. In H9c2 myocytes treated for 48 h with ANG II (100 nmol/l) or H(2)O(2) (10 micromol/l) showed delayed macroscopic inactivation, increased late current, and 59.6% and 53.8% reductions in Na(+) current, respectively (P < or = 0.01). By quantitative real-time RT-PCR, the cardiac Na(+) channel (scn5a) mRNA abundance declined by 47.3% (P < 0.01) in H9c2 myocytes treated for 48 h with 100 nmol/l ANG II. A similar change occurred with 20 micromol/l H(2)O(2) (46.9%, P < 0.01) after 48 h. Comparable effects were seen in acutely isolated ventricular myocytes. The effects of ANG II could be inhibited by prior treatment of H9c2 cells with scavengers of reactive oxygen species or an inhibitor of the NADPH oxidase. Mutation of the scn5a promoter NF-kappaB binding site prevented decreased activity in response to ANG II and H(2)O(2). Gel shift and chromosomal immunoprecipitation assays confirmed that nuclear factor (NF)-kappaB bound to the scn5a promoter in response to ANG II and H(2)O(2). Overexpression of the p50 subunit of NF-kappaB in H9c2 cells reduced scn5a mRNA (77.3%, P < 0.01). In conclusion, ANG II can decrease scn5a transcription and current. This effect appears to be through production of H(2)O(2) resulting in NF-kappaB binding to the Na(+) channel promoter.

Medical management of the failing Fontan

The Fontan operation accomplishes complete separation of systemic venous blood from pulmonary venous circulation in patients with single ventricle anatomy. Operative survival since the first description of the Fontan operation is excellent in the current era through modifications in surgical techniques, identification of patient-specific risk factors, and advances in postoperative care. Improved early outcomes have also resulted in a decline in late mortality for patients who have undergone staged palliation with the Fontan operation. As the number of late survivors from the Fontan operation increases, caregivers will be evermore faced with the challenge of recognizing and managing the patient with failing Fontan physiology. Even after excellent early results, patients with single ventricle lesions remain at risk of progressive ventricular dysfunction, dysrhythmias, progressive hypoxemia, elevated pulmonary vascular resistance, and protein-losing enteropathy, which can result in morbidities including but not limited to, myocardial failure, thromboembolism, and stroke. Consequently, continued long-term survival of patients who undergo the Fontan operation is dependent upon preservation of single ventricle function, avoidance of late complications, and, in the patient with a failing Fontan, recognition and treatment of the underlying pathophysiologic process that has resulted in Fontan failure.

Aldosterone blockade: an emerging strategy for abrogating progressive renal disease

In recent years, there has been a striking paradigm shift with respect to our understanding of the widespread effects of aldosterone. Whereas the role of angiotensin II in mediating progressive renal disease and heart failure has been documented extensively, more recent evidence has implicated aldosterone as an important pathogenetic factor in addition to angiotensin II in the development of these diseases. The focus of this review is aldosterone and progressive renal dysfunction. The extensive preclinical and clinical evidence supporting the efficacy of aldosterone blockade in abrogating proteinuria is summarized. The frequency and clinical importance of aldosterone "escape" is reviewed. Therapeutic considerations to reduce the incidence of hyperkalemia with aldosterone blockade are discussed. The studies reviewed have several important clinical implications for considering new treatment algorithms for patients with incipient nephropathy. Because full doses of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers attenuate but do not abrogate progression of renal dysfunction, add-on aldosterone blockade therapy may constitute a rational therapeutic strategy for retarding progression of renal disease.

Aldosterone antagonists in the treatment of heart failure

PURPOSE

The clinical benefits, adverse effects, pharmacokinetics, and recommendations for the appropriate use of the aldosterone antagonists spironolactone and eplerenone in patients with heart failure are reviewed.

SUMMARY

Heart failure is a clinical syndrome characterized by the functional inability of the ventricle to meet the metabolic demands of the body. Renal hypoperfusion occurs as a result of reduced cardiac output, resulting in the activation of the renin-angiotensin-aldosterone system, which compensates for the hypoperfusion. However, this contributes to the pathology of the disease by, among other actions, increasing the release of aldosterone. Aldosterone has been shown to cause coronary inflammation, cardiac hypertrophy, myocardial fibrosis, ventricular arrhythmias, and ischemic and necrotic lesions. There are currently two aldosterone antagonists commercially available in the United States, spironolactone and eplerenone. Spironolactone is a nonselective aldosterone antagonist, and eplerenone is selective to the aldosterone receptor. Although numerous clinical trials have evaluated the efficacy of each drug, no studies have directly compared spironolactone and eplerenone. Both have been shown to improve morbidity and mortality in patients with advanced heart failure. Adverse effects of both spironolactone and eplerenone include potentially life-threatening hyperkalemia, which can be induced by renal insufficiency, diabetes mellitus, advanced heart failure, advanced age, and concurrent drug therapy.

CONCLUSION

Spironolactone and eplerenone are life-saving agents in patients with advanced heart failure and may benefit patients with mild heart failure. Potassium and renal function must be routinely assessed to minimize the risk of life-threatening hyperkalemia.

A look between the cardiomyocytes: the extracellular matrix in heart failure

The extracellular matrix (ECM) of the heart dynamically interacts with various cellular components of the myocardium, including the myocytes and connective tissue cells. With the development and progression of heart failure, left ventricular (LV) myocardial remodeling occurs. The progression of LV remodeling is accompanied by alterations in the structure and function of the ECM that occur after injury resulting from neurohormonal activation, changes in LV loading conditions, and alterations in myocardial perfusion and metabolism and is secondary to a host of nonmyocyte signaling pathways that affect repair and remodeling of the myocardium as a whole. This article attempts to review some of these processes and their interactions and to provide a focus to the often overlooked contribution of the ECM to the development and progression of heart failure and thereby its potential role as a target for therapy for heart failure.

Diastolic Heart Failure in the Elderly and the Potential Role of Aldosterone Antagonists

The overall incidence of heart failure increases with age, affecting up to 10% of people >65 years of age. Diastolic heart failure is also age-dependent, increasing from <15% in middle-aged patients to >40% in patients > or =70 years of age. Elderly patients usually have other co-morbid conditions such as hypertension, diabetes mellitus, coronary artery disease and atrial fibrillation that can adversely affect the diastolic properties of the heart. The clinical manifestations of diastolic heart failure are similar to those of systolic heart failure. In practice, the diagnosis is generally based on the finding of typical symptoms and signs of heart failure with preserved left ventricular ejection fraction and no valvular abnormalities on echocardiography. Altered ventricular relaxation and abnormal ventricular filling are the hallmarks of diastolic heart failure. Cardiac fibrosis and cellular disarray lead to the alterations in the diastolic properties of the heart. Diffuse foci of fibrosis in the myocardium have been reported with advancing age. Aldosterone has been shown to play a crucial role in the development of cardiac fibrosis via a direct effect on the mineralocorticoid receptors within the myocardium. Unlike the situation with treatment of systolic heart failure, few clinical trials are available to guide the management of patients with diastolic heart failure. In the absence of controlled clinical trials, patient management is based on control of the physiological factors (blood pressure, heart rate, blood volume and myocardial ischaemia) that are known to exert important effects on ventricular relaxation. Aldosterone antagonists inhibit the deposition of collagen matrix in the myocardium, thereby targeting the basic pathophysiological mechanism of diastolic dysfunction. Thus, they appear to represent a promising therapeutic approach for this condition. Currently, only small clinical trials supporting this therapy are available and large clinical trials evaluating long-term outcomes in diastolic dysfunction are therefore needed.

Aldosterone receptor antagonism in heart failure

The renin-angiotensin-aldosterone system plays a major role in the pathophysiology of heart failure. Aldosterone is one of the central mediators involved in the cardiac remodeling process. Its classic effect in heart failure is attributed to mineralocorticoid receptor-mediated salt and fluid retention leading to increased afterload. New evidence demonstrates nonclassic effects of increased collagen synthesis and myocardial fibrosis resulting in left ventricular hypertrophy. Antagonism of aldosterone receptors with spironolactone benefits patients with severe heart failure, and eplerenone benefits those after myocardial infarction who have left ventricular dysfunction. Future research is directed at aldosterone antagonism in patients with mild-to-moderate heart failure, coronary artery disease treated with percutaneous coronary intervention, and nephropathy complicated by diabetes mellitus.

The risks and benefits of aldosterone antagonists

Spironolactone and eplerenone are mineralocorticoid- blocking agents used for their ability to block a host of epithelial and nonepithelial actions of aldosterone. These compounds are of proven benefit in reducing blood pressure and urine protein excretion, and in conferring cardiovascular gain in diverse circumstances of heart failure. However, as enthusiasm grows for use of mineralocorticoid-blocking agents, the risks inherent to use of such drugs become more pertinent. Whereas the endocrine side effects of spironolactone are in reality little more than a cosmetic disfigurement, the potassium-sparing properties of spironolactone and eplerenone can prove life-threatening if hyperkalemia develops. However, for most patients the risk of developing hyperkalemia should not dissuade the prudent clinician from use of these compounds. Hyperkalemia should be considered as a possibility in any patient receiving these medications and as such is best addressed preemptively.

Stress triggered rise in plasma aldosterone is lessened by chronic nicotine infusion

The ability of nicotine infusion to modulate plasma aldosterone levels in response to different stressors was investigated. Sprague-Dawley rats given nicotine (5 mg/kg/day) or saline for 14 days were subjected to stress. Baseline plasma aldosterone (86+/-17 pmol/l) was unaffected by nicotine. Aldosterone was significantly elevated by restraint (450+/-72 pmol/l) and especially with cold (1249+/-172 pmol/l) or immobilization (1779+/-247 pmol/l) stress. Nicotine infusion attenuated the rise in aldosterone with restraint and cold stress, but not immobilization. These results reveal that nicotine infusion can attenuate the aldosterone response, depending on the type of stress.

Pharmacokinetics and Pharmacodynamics of Mineralocorticoid Blocking Agents and their Effects on Potassium Homeostasis

Spironolacotone and eplerenone are mineralocorticoid-blocking agents used for their ability to block both the epithelial and non-epithelial actions of aldosterone. Spironolactone is a non-selective mineralocorticoid receptor antagonist with moderate affinity for both progesterone and androgen receptors. The latter property increases the likelihood of endocrine side effects with spironolactone including loss of libido, menstrual irregularities, gynecomastia and impotence. Eplerenone is a next generation aldosterone receptor antagonist selective for aldosterone receptors alone. This lesser affinity for progesterone and androgen receptors was arrived at by replacing the 17-alpha -thioacetyl group of spironolactone with a carbomethoxy group. Eplerenone is further distinguished from spironolactone by its shorter half-life and the fact that it does not have any active metabolites. Both eplerenone and spironolactone are effective antihypertensive agents and each has been shown to improve the morbidity and mortality of heart failure. Eplerenone or spironolactone use can increase serum potassium values and occasionally results in clinically relevant hyperkalemia. This is more apt to occur with spironolactone due to the very long half-life of several of its active metabolites.

Eplerenone in the treatment of chronic heart failure

There has been a recent revival of interest in aldosterone receptor antagonists for the treatment of chronic heart failure. This was largely triggered by fresh insights into the role of aldosterone in a number of key pathophysiological processes, including fibrosis and remodeling, inflammation, and the potentiation of catecholamine effects. The therapeutic efficacy of spironolactone (Aldactone), Pfizer) in severe chronic heart failure was established by the Randomized Aldactone Evaluation Study, but hormonal side effects (gynecomastia) associated with the drug posed a problem. More recently, the Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study has provided firm support for the use of eplerenone (Inspra, Pfizer) in heart failure following acute myocardial infarction in addition to neurohormonal blockade with angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers and beta-blockers. This strategy can be expected to benefit both mortality and morbidity. Due to the fact that eplerenone is a selective aldosterone receptor antagonist, it does not cause troublesome hormonal side effects. This is an important feature of the drug that is likely to help maintain compliance.

Brain mineralocorticoid receptors: orchestrators of hypertension and end-organ disease

PURPOSE OF REVIEW

'New' tasks have been discovered for aldosterone and its receptor, the mineralocorticoid receptor, within both epithelial tissues of vectorial ion and water transport, such as the kidney, and non-epithelial organs, including the brain, heart and vessels. Promising results of clinical trials using low doses of mineralocorticoid receptor antagonists to forestall end-organ disease is resulting in an increase in their use, yet the biology of the mineralocorticoid receptor is far from clear.

RECENT FINDINGS

Mineralocorticoid receptors within the kidney, heart and blood vessels mediate direct effects of aldosterone, including tissue inflammation, hypertrophy and fibrosis, that are independent of blood pressure. Activation, by aldosterone, of mineralocorticoid receptors in the brain increases central sympathetic nervous system drive to the periphery, thereby producing hypertension through multiple mechanisms, and increases levels of proinflammatory cytokines in both the circulation and peripheral tissues. Blocking of the mineralocorticoid receptor of the forebrain lowers the levels of peripheral tissue cytokines, including those induced by ischemic injury in the heart. Aldosterone is produced within the heart, blood vessels and brain, potentially liberating regulation of local concentrations of the steroid from peripheral mechanisms of control. A conundrum yet to be explained is the ligand-dependent functional specificity of the mineralocorticoid receptor in some non-epithelial tissues, which may be crucial to our understanding the end-organ pathophysiology of hypertension.

SUMMARY

New technology is rapidly adding layers of complexity to, rather than simplifying, our understanding of the facile terms 'hemodynamic homeostasis' and 'end-organ' disease, but within this new knowledge lies the promise of better, more precise treatment of hypertension and its sequelae.

Aldosterone and aldosterone antagonism in systemic hypertension

Aldosterone mediates both water and electrolyte balance by acting on the renal mineralocorticoid receptors. Recent experimental studies have also documented the presence of these receptors in other body organs, including the brain, blood vessels, and heart, suggesting that aldosterone plays a larger role in normal physiologic function and in cardiovascular diseases such as systemic hypertension and congestive heart failure (CHF). The nonspecific aldosterone inhibitor spironolactone, and the selective aldosterone inhibitor eplerenone, are both approved for clinical use in treating patients with hypertension and/or symptomatic CHF. Studies have shown that spironolactone lowers blood pressure, improves endothelial function, reduces myocardial hypertrophy and fibrosis, and lowers the incidence of fatal arrhythmias. Eplerenone, which is more specific for the mineralocorticoid receptor, appears to provide all the beneficial effects of spironolactone in hypertensive patients, with the potential to modify many of the side effects related to nonspecific steroid-receptor blockade. Hyperkalemia remains a potential problem with all aldosterone antagonists.

The cardiovascular effects of eplerenone, a selective aldosterone-receptor antagonist

BACKGROUND

The role of the renin-angiotensin-aldosterone system in the pathophysiology and treatment of hypertension and heart failure has been extensively studied. Angiotensin-converting enzyme inhibitors and angiotensin II-receptor blockers have been shown to effectively reduce blood pressure, protect the kidney, and reduce morbidity and mortality in patients with heart failure. Therefore, there is increased interest in the effects of aldosterone and the use of aldosterone-receptor antagonists in the treatment of cardiovascular disease. Eplerenone is the first selective aldosterone-receptor antagonist approved for the treatment of hypertension and left ventricular (LV) dysfunction after acute myocardial infarction (AMI).

OBJECTIVE

The goal of this article was to review the pharmacologic properties, clinical efficacy, and tolerability of eplerenone in the treatment of hypertension, LV dysfunction, and proteinuria.

METHODS

Relevant English-language articles were identified through searches of MEDLINE (1966-May 2003), Current Contents, and International Pharmaceutical Abstracts (1970-May 2003) using the terms hypertension, heart failure, eplerenone, aldosterone, and aldosterone antagonist. Other pertinent publications were identified from the reference lists of the identified articles. Information was also obtained from abstracts presented at national meetings and data on file with the manufacturer.

RESULTS

In clinical trials, eplerenone alone and in combination with renin-angiotensin blockade significantly reduced both systolic and diastolic blood pressure compared with placebo (P < 0.05 to P < 0.001). In EPHESUS (Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study), the addition eplerenone to optimal medical therapy reduced morbidity and mortality in patients with AMI and LV dysfunction, although the incidence of serious hyperkalemia was also significantly greater. In comparisons with spironolactone, eplerenone was associated with a lower incidence of gynecomastia and other sex hormone-related adverse effects.

CONCLUSIONS

Either alone or in combination with other antihypertensive agents, eplerenone appears to be effective for the treatment of hypertension. Morbidity and mortality were reduced when eplerenone was added to standard therapy for LV dysfunction complicating AMI. The use of eplerenone for hypertension or heart failure may be limited in patients at risk for hyperkalemia.

Eplerenone

Aldosterone has been implicated for many years as an important substance in the pathogenesis of heart disease. Elevated aldosterone concentrations have been documented in patients with hypertension and heart failure, leading to the use of aldosterone antagonists for the treatment of these conditions. Spironolactone has been used for nearly 2 decades for the treatment of hypertension, and more recently, has become a standard agent for the treatment of systolic heart failure. Spironolactone, however, is a nonselective antagonist of the aldosterone receptor, binding also to other steroid receptors and causing a significant percentage of patients to have sex hormone-related adverse effects such as gynecomastia. Eplerenone is the first of a new class of drugs known as selective aldosterone receptor antagonists, which selectively block the aldosterone receptor with minimal effect at other steroid receptors, thereby minimizing many of the hormonal side effects seen with spironolactone. Eplerenone has been shown to be beneficial both as monotherapy and combination therapy for lowering elevated blood pressure in patients with hypertension. The antihypertensive efficacy of eplerenone is roughly similar to that of other antihypertensive agents, although in 1 study black patients responded better with eplerenone than losartan. In addition, eplerenone has demonstrated some renoprotective effects in diabetic patients with hypertension. Recently, eplerenone was shown to significantly reduce mortality and cardiovascular morbidity in post-myocardial infarction patients with systolic heart failure currently taking standard heart failure medications. Eplerenone is generally well tolerated, although hyperkalemia with this agent is of some concern. Eplerenone is metabolized by CYP3A4 and administration with potent inhibitors of this enzyme is contraindicated because of the risk of hyperkalemia. In summary, eplerenone has proven to be beneficial in treating hypertension and post-myocardial infarction heart failure. Its exact place in therapy will in large part be determined by its cost and whether or not future studies will be able to demonstrate a clinical benefit of this agent over spironolactone or other currently available treatments.