Mineralocorticoid antagonists and ENaC inhibitors in hyperaldosteronism

Comparison of different medical treatments for primary hyperaldosteronism: a systematic review and network meta-analysis

Background

The effectiveness and side effects between different medical treatments in patients with primary hyperaldosteronism have not been systematically studied.

Objective

To analyze the efficacy between different mineralocorticoid receptor antagonists (MRAs) and epithelial sodium channel (ENaC) inhibitors in a network meta-analysis (NMA) framework, while also evaluating adverse events.

Design

Systematic review and NMA.

Data sources and methods

The systematic review and NMA was reported according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed, MEDLINE, the Cochrane library, and Excerpta Medica database (EMBASE) were searched for randomized controlled trials (RCTs) involving adult patients with primary hyperaldosteronism until 23 June 2023. Studies that compared the efficacy and side effects of different medical treatments of primary hyperaldosteronism were included. The primary outcomes included the effect on blood pressure, serum potassium, and major adverse cardiovascular events. The secondary outcomes were adverse events related to MRAs (hyperkalemia and gynecomastia). Frequentist NMA and pairwise meta-analysis were conducted.

Results

A total of 5 RCTs comprising 392 participants were included. Eplerenone, esaxerenone, and amiloride were compared to spironolactone and demonstrated comparable effect on the reduction of systolic blood pressure. In comparison to spironolactone, eplerenone exhibited a less pronounced effect on reducing diastolic blood pressure [-4.63 mmHg; 95% confidence interval (CI): -8.87 to -0.40 mmHg] and correcting serum potassium (-0.2 mg/dL; 95% CI: -0.37 to -0.03 mg/dL). Spironolactone presented a higher risk of gynecomastia compared with eplerenone (relative risk: 4.69; 95% CI: 3.58-6.14).

Conclusion

The present NMA indicated that the blood pressure reduction and potassium-correcting effects of the three MRAs may demonstrate marginal differences, with confidence levels in the evidence being very low. Therefore, further research is needed to explore the efficacy of these MRAs, especially regarding their impact on mortality and cardiovascular outcomes.

Trial registration

PROSPERO (CRD: 42023446811).

Sensory Nutrition and Bitterness and Astringency of Polyphenols

Recent studies have demonstrated that the interaction of dietary constituents with taste and olfactory receptors and nociceptors expressed in the oral cavity, nasal cavity and gastrointestinal tract regulate homeostasis through activation of the neuroendocrine system. Polyphenols, of which 8000 have been identified to date, represent the greatest diversity of secondary metabolites in plants, most of which are bitter and some of them astringent. Epidemiological studies have shown that polyphenol intake contributes to maintaining and improving cardiovascular, cognitive and sensory health. However, because polyphenols have very low bioavailability, the mechanisms of their beneficial effects are unknown. In this review, we focused on the taste of polyphenols from the perspective of sensory nutrition, summarized the results of previous studies on their relationship with bioregulation and discussed their future potential.

Salt Sensitivity of Blood Pressure in Women

Several clinical and large population studies indicate that women are more salt-sensitive than men, yet the precise mechanisms by which the sexually dimorphic onset manifests remains incompletely understood. Here, we evaluate recent epidemiological data and highlight current knowledge from studies investigating sex-specific mechanisms of salt-sensitive blood pressure (SSBP). Emerging evidence indicates that women of all ethnicities are more salt-sensitive than men, at all ages both premenopausal and postmenopausal. However, menopause exacerbates severity and prevalence of SSBP, suggesting that female sex chromosomes predispose to and female sex hormones mitigate SSBP. Results from both human and rodent studies support the contribution of enhanced and inappropriate activation of the aldosterone-ECMR (endothelial cell mineralocorticoid receptor) axis promoting vascular dysfunction in females. Increases in adrenal response to angiotensin II, in association with higher ECMR expression and activation of endothelial ENaC (epithelial sodium channel) in females compared to males, are emerging as central players in the development of endothelial dysfunction and SSBP in females. Female sex increases the prevalence and susceptibility of SSBP and sex hormones and sex chromosome complement may exert antagonistic effects in the development of the female heightened SSBP.

Pharmacological significance of extra-oral taste receptors

It has recently been shown that taste receptors, in addition to being present in the oral cavity, exist in various extra-oral organs and tissues such as the thyroid, lungs, skin, stomach, intestines, and pancreas. Although their physiological function is not yet fully understood, it appears that they can help regulate the body's homeostasis and provide an additional defense function against pathogens. Since the vast majority of drugs are bitter, the greatest pharmacological interest is in the bitter taste receptors. In this review, we describe how bitter taste 2 receptors (TAS2Rs) induce bronchodilation and mucociliary clearance in the airways, muscle relaxation in various tissues, inhibition of thyroid stimulating hormone (TSH) in thyrocytes, and release of glucagon-like peptide-1 (GLP-1) and ghrelin in the digestive system. In fact, substances such as dextromethorphan, chloroquine, methimazole and probably glimepiride, being agonists of TAS2Rs, lead to these effects. TAS2Rs and taste 1 receptors (TAS1R2/3) are G protein-coupled receptors (GPCR). TAS1R2/3 are responsible for sweet taste perception and may induce GLP-1 release and insulin secretion. Umami taste receptors, belonging to the same superfamily of receptors, perform a similar function with regard to insulin. The sour and salty taste receptors work in a similar way, both being channel receptors sensitive to amiloride. Finally, gene-protein coupled receptor 40 (GPR40) and GPR120 for fatty taste perception are also protein-coupled receptors and may induce GLP-1 secretion and insulin release, similar to those of other receptors belonging to the same superfamily.

Primary aldosteronism

Primary aldosteronism (PA) is a common cause of secondary hypertension caused by excessive and inappropriate secretion of the hormone aldosterone from one or both adrenal glands. The prevalence of PA ranges from 10% in the general hypertensive population to 20% in resistant hypertension, yet only a small fraction of patients is diagnosed. Disease and symptom recognition, screening in indicated populations, multidisciplinary communication, and appropriate imaging and biochemical workup can identify patients who might benefit from effective and targeted treatment modalities. Effective treatments available include both surgical and medical approaches, usually dependent on the subtype of PA present. Our collective understanding of the pathophysiology of PA is expanded by recent developments in molecular biology and genetics, including understanding the specific somatic and germline mutations involved in pathogenesis. We review the pathophysiology, diagnostic workup, and treatment considerations for this disease process.