Clinical Implications of SARS-CoV-2 Interaction With Renin Angiotensin System: JACC Review Topic of the Week.

Severe acute respiratory-syndrome coronavirus-2 (SARS-CoV-2) host cell infection is mediated by binding to angiotensin-converting enzyme 2 (ACE2). Systemic dysregulation observed in SARS-CoV was previously postulated to be due to ACE2/angiotensin 1-7 (Ang1-7)/Mas axis downregulation; increased ACE2 activity was shown to mediate disease protection. Because angiotensin II receptor blockers, ACE inhibitors, and mineralocorticoid receptor antagonists increase ACE2 receptor expression, it has been tacitly believed that the use of these agents may facilitate viral disease; thus, they should not be used in high-risk patients with cardiovascular disease. Based on the anti-inflammatory benefits of the upregulation of the ACE2/Ang1-7/Mas axis and previously demonstrated benefits of lung function improvement in SARS-CoV infections, it has been hypothesized that the benefits of treatment with renin-angiotensin system inhibitors in SARS-CoV-2 may outweigh the risks and at the very least should not be withheld.

Mineralocorticoid receptor antagonists and kidney diseases: pathophysiological basis.

Chronic kidney disease (CKD) represents a global health concern, and its prevalence is increasing. The ultimate therapeutic option for CKD is kidney transplantation. However, the use of drugs that target specific pathways to delay or halt CKD progression, such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and sodium-glucose co-transporter-2 (SGLT-2) inhibitors is limited in clinical practice. Mineralocorticoid receptor activation in nonclassical tissues, such as the endothelium, smooth muscle cells, inflammatory cells, podocytes, and fibroblasts may have deleterious effects on kidney structure and function. Several preclinical studies have shown that mineralocorticoid receptor antagonists (MRAs) ameliorate or cure kidney injury and dysfunction in different models of kidney disease. In this review, we present the preclinical evidence showing a benefit of MRAs in acute kidney injury, the transition from acute kidney injury to CKD, hypertensive and diabetic nephropathy, glomerulonephritis, and kidney toxicity induced by calcineurin inhibitors. We also discuss the molecular mechanisms responsible for renoprotection related to MRAs that lead to reduced oxidative stress, inflammation, fibrosis, and hemodynamic alterations. The available clinical data support a benefit of MRA in reducing proteinuria in diabetic kidney disease and improving cardiovascular outcomes in CKD patients. Moreover, a benefit of MRAs in kidney transplantation has also been observed. The past and present clinical trials describing the effect of MRAs on kidney injury are presented, and the risk of hyperkalemia and use of other options, such as potassium binding agents or nonsteroidal MRAs, are also addressed. Altogether, the available preclinical and clinical data support a benefit of using MRAs in CKD, an approach that should be further explored in future clinical trials.

The Effects of Aldosterone Antagonists in Patients With Resistant Hypertension: A Meta-Analysis of Randomized and Nonrandomized Studies.

BACKGROUND: A few studies have shown aldosterone antagonists (AA) to be effective therapy in patients with resistant hypertension (RH). We performed a meta-analysis of randomized and nonrandomized studies of AA in patients with RH. METHODS: We searched PUBMED, EMBASE, and CENTRAL for studies on the use of AA in patients with RH. Meta-analysis was performed using random-effects model. The change in office and ambulatory blood pressures (BP), effects on biochemical profile, change in the number of antihypertensive agents, and adverse events were main outcomes. RESULTS: We included 15 studies (3 randomized controlled trials, 1 nonrandomized comparative study, and 11 single-arm studies) with 1,204 total patients in the meta-analysis. In comparative studies, AA reduced systolic BP (SBP) by 24.26 mm Hg (95% CI: 8.65-39.87, P = 0.002) and diastolic BP (DBP) by 7.79 mm Hg (3.79-11.79, P = 0.0001). Similarly, AA reduced SBP by 22.74 mm Hg (18.21-27.27, P < 0.00001) and DBP by 10.49 mm Hg (8.85-12.13, P < 0.00001) in single-arm studies. AA resulted in significant change in serum electrolytes in single-arm studies but not in comparative studies. Significantly more adverse events were noted in single-arm studies but not in comparative studies. CONCLUSIONS: On the basis of the current meta-analysis, we conclude that AA is safe and effective therapy in patients with RH.

Management of hypertension and heart failure in patients with Addison's disease.

Addison's disease may be complicated by hypertension and less commonly by heart failure. We review the pathophysiology of the renin-angiotensin-aldosterone axis in Addison's disease and how this is altered in the setting of hypertension and heart failure. An essential first step in management in both conditions is optimizing glucocorticoid replacement and considering dose reduction if excessive. Following this, if a patient with Addison's disease remains hypertensive, the fludrocortisone dose should be reviewed and reduced if there are clinical and/or biochemical signs of mineralocorticoid excess. In the absence of such signs, where the renin is towards the upper end of the normal range or elevated, an angiotensin II (AII) receptor antagonist or angiotensin converting enzyme (ACE) inhibitor is the treatment of choice, and the fludrocortisone dose should remain unchanged. Dihydropyridine calcium channel blockers are clinically useful as second line agents, but diuretics should be avoided. In the setting of heart failure, there is an increase in total body sodium and water; therefore, it is appropriate to reduce and rarely consider ceasing the fludrocortisone. Loop diuretics may be used, but not aldosterone antagonists such as spironolactone or eplerenone. Standard treatment with ACE inhibitors, or as an alternative, AII receptor antagonists, are appropriate. Measurements of renin are no longer helpful in heart failure to determine the volume status but plasma levels of brain natriuretic peptide (BNP/proBNP) may help guide therapy.

Eplerenone : a review of its use in left ventricular systolic dysfunction and heart failure after acute myocardial infarction.

Eplerenone (Inspra) is a selective aldosterone blocker. Oral eplerenone is approved for use in patients with left ventricular (LV) systolic dysfunction and clinical evidence of heart failure following acute myocardial infarction (MI) in the US and in European countries (e.g. the UK and The Netherlands). The addition of eplerenone to standard medical therapy significantly improved mortality and morbidity in patients with LV systolic dysfunction and clinical evidence of heart failure following acute MI in the large, well designed EPHESUS (Eplerenone Post-acute myocardial infarction Heart failure Efficacy and SUrvival Study) trial. The beneficial effects of eplerenone on all-cause mortality and cardiovascular mortality were seen within 30 days of randomisation. Eplerenone was generally well tolerated. Although a higher incidence of hyperkalaemia occurred with eplerenone than with placebo, the incidence of hypokalaemia was significantly lower with eplerenone treatment. Thus, the addition of eplerenone to standard medical therapy is an important new strategy for further improving mortality and morbidity in post-MI patients with LV systolic dysfunction and heart failure.

Assessment of the novel selective aldosterone blocker eplerenone using ambulatory and clinical blood pressure in patients with systemic hypertension.

Eplerenone is a highly selective aldosterone blocking agent, which was recently approved for the treatment of hypertension and has also been shown to reduce mortality in post-myocardial infarction patients with heart failure. To assess its usefulness in patients with essential hypertension, we performed a 12-week, double-blind, placebo-controlled, parallel-arm, fixed-dose study over a range of doses using clinic and ambulatory blood pressure (BP). After single-blind placebo therapy for 3 to 4 weeks to obtain baseline measures, 400 patients were randomized to receive placebo or 1 of 4 doses of eplerenone (25, 50, 100, and 200 mg once daily). In addition, changes from baseline in serum potassium, active renin activity, and serum aldosterone were assessed. After 12 weeks of therapy, reductions in clinic BP showed a significant dose response in which 25 mg of eplerenone achieved statistical significance compared with placebo for systolic BP; maximum clinic BP reduction was achieved with the 100 mg dose. Ambulatory BP monitoring showed that all doses of eplerenone (25 to 200 mg/day) lowered BP significantly greater than placebo with a significant dose response. The 24-hour mean BP reductions ranged from 6.4/4.4 to 10.3/5.7 mm Hg on eplerenone compared with 1.3/0.8 mm Hg on placebo. One patient on placebo and 1 patient on 200 mg of eplerenone had episodes of elevated serum potassium levels (>5.5 mEq/L). Increases in serum aldosterone were related to dose but not to reductions in 24-hour BP. Side effects and withdrawal rates attributed to eplerenone were similar to those of placebo. These data show that eplerenone is an effective antihypertensive agent at doses as low as 25 mg/day. The top effective dose in stage 1 to 3 hypertension based on clinic and ambulatory BP was 100 mg once daily. The incidence of elevated serum potassium levels was not increased across doses of eplerenone in this study.

Spironolactone in heart failure--a revived role for an old drug.

Spironolactone is an aldosterone antagonist which has been used as a mild potassium-sparing diuretic and in treatment of ascites in liver failure. Recent studies have shown that it has an additive effect to those of ACE inhibitors in heart failure treatment.

Mineralocorticoid receptor antagonists: the evolution of utility and pharmacology.

For more than 30 years after the discovery of aldosterone, scientists believed that its sole site of action was at epithelial tissues, most notably the kidney, where it mediated the transport of Na and K. It was soon recognized aldosterone contributed to several diseases by causing edema. Armed with this information, scientists set out more than 30 years ago to develop an antagonist of the mineralocorticoid receptor for the treatment of edematous states. From this effort, spironolactone (Aldactone was discovered. Spironolactone acts functionally as a competitive inhibitor of the mineralocorticoid (aldosterone) receptor, and although spironolactone is an effective mineralocorticoid receptor antagonist, it is not without limitations. These limitations include unwanted progestational and antiadrogenic side effects that limit its use in the chronic treatment of disease. In addition to its actions at the collecting tubule, aldosterone can participate in pathophysiology by actions at the heart, vasculature, and kidney, and it is likely that the most significant contributions to cardiovascular disease are due to actions at these sites rather than those related to Na and water retention. This is underscored by the recent clinical results from the RALES-004 Trial in which treatment with Aldactone demonstrated a significant benefit on mortality in patients with severe heart failure. The limited utility of spironolactone owing to the aforementioned steroid-related side effects has been especially frustrating, given the newly recognized role of aldosterone in cardiovascular disease. To obviate these limitations, eplerenone is currently being developed by Searle. Eplerenone is a competitive antagonist of the mineralocorticoid receptor that takes advantage of replacing the 17alpha-thoacetyl group of spironolactone with a carbomethoxy group, conferring excellent selectivity for the mineralocorticoid receptor over other steroid receptors. The pharmacological profile of eplerenone positions it to be an effective and selective mineralocorticoid receptor antagonist.

Assessment of the antimineralocorticoid effect of RU 28318 in healthy men with induced exogenous and endogenous hypermineralocorticism.

The antimineralocorticoid effect of a single dose of RU 28318, has been assessed in healthy men with exogenous or endogenous hypermineralocorticism. For exogenous hypermineralocorticism induced by ingestion of 9 alpha-fluorohydrocortisone (9 alpha-FHC) and aldosterone infusion, RU 28318 100 mg (9 alpha-FHC ingestion) or 200 mg (aldosterone infusion) was administered, and its effect compared with identical doses of spironolactone or a placebo. For endogenous hypermineralocorticism induced by ingestion of furosemide, RU 28318 100 and 300 mg was tested in comparison with 100 mg spironolactone or placebo. In all 3 studies, both RU 28318 and spironolactone significantly raised the urinary Na/K ratio when compared to placebo administration. No significant difference was apparent between RU 28318 and spironolactone. Thus, a single dose of RU 28318 in man has an antimineralocorticoid effect identical to those produced by the identical molar dose of spironolactone. In addition, the results show that furosemide-induced hyperaldosteronism constitutes a simple and reproducible test for assessing the antimineralocorticoid effect of a drug.