Angiotensin-Converting Enzyme Inhibitors and Angiotensin Receptor Blockers in Hypertension Due to Primary Aldosteronism: A Case for Exclusion

Aldosterone and aldosterone synthase inhibitors in cardiorenal disease

Modulation of the renin-angiotensin-aldosterone system is a foundation of therapy for cardiovascular and kidney diseases. Excess aldosterone plays an important role in cardiovascular disease, contributing to inflammation, fibrosis, and dysfunction in the heart, kidneys, and vasculature through both genomic and mineralocorticoid receptor (MR)-mediated as well as nongenomic mechanisms. MR antagonists have been a key therapy for attenuating the pathologic effects of aldosterone but are associated with some side effects and may not always adequately attenuate the nongenomic effects of aldosterone. Aldosterone is primarily synthesized by the CYP11B2 aldosterone synthase enzyme, which is very similar in structure to other enzymes involved in steroid biosynthesis including CYP11B1, a key enzyme involved in glucocorticoid production. Lack of specificity for CYP11B2, off-target effects on the hypothalamic-pituitary-adrenal axis, and counterproductive increased levels of bioactive steroid intermediates such as 11-deoxycorticosterone have posed challenges in the development of early aldosterone synthase inhibitors such as osilodrostat. In early-phase clinical trials, newer aldosterone synthase inhibitors demonstrated promise in lowering blood pressure in patients with treatment-resistant and uncontrolled hypertension. It is therefore plausible that these agents offer protection in other disease states including heart failure or chronic kidney disease. Further clinical evaluation will be needed to clarify the role of aldosterone synthase inhibitors, a promising class of agents that represent a potentially major therapeutic advance.

Prescribed drugs containing nitrogen heterocycles: an overview

Heteroatoms as well as heterocyclic scaffolds are frequently present as the common cores in a plethora of active pharmaceuticals natural products. Statistically, more than 85% of all biologically active compounds are heterocycles or comprise a heterocycle and most frequently, nitrogen heterocycles as a backbone in their complex structures. These facts disclose and emphasize the vital role of heterocycles in modern drug design and drug discovery. In this review, we try to present a comprehensive overview of top prescribed drugs containing nitrogen heterocycles, describing their pharmacological properties, medical applications and their selected synthetic pathways. It is worth mentioning that the reported examples are actually limited to current top selling drugs, being or containing N-heterocycles and their synthetic information has been extracted from both scientific journals and the wider patent literature.

Outcomes of drug-based and surgical treatments for primary aldosteronism

Treatments for primary aldosteronism (PA) aim to correct or prevent the deleterious consequences of hyperaldosteronism: hypertension, hypokalemia, and direct target organ damage. Patients with unilateral PA considered fit for surgery can undergo laparoscopic adrenalectomy, which significantly decreases blood pressure (BP) and medications in most cases and cures hypertension in about 40%. Mineralocorticoid receptor antagonists (MRA) are used to treat patients with bilateral PA and those with unilateral PA if surgery is not possible or not desired. Spironolactone is more potent than eplerenone, but high doses are poorly tolerated in men. MRA can be replaced or complemented with epithelial sodium channel blockers, such as amiloride. Thiazide diuretics and calcium channel blockers are used when the first-line drugs are insufficient to control BP. Dietary sodium restriction should be implemented in all cases because the deleterious consequences of hyperaldosteronism are dependent on salt loading. Several studies comparing the results of surgery and MRA have reported no differences in terms of BP, serum potassium concentration, or cardiovascular and kidney outcomes, although the benefits of treatment tend to be observed sooner with surgery. Patients with PA display relative glomerular hyperfiltration, which is reversed by specific treatment, revealing CKD in 30% of patients. However, further kidney damage is lessened by the treatment of PA.

Prediction of successful outcome in patients with primary aldosteronism

Primary aldosteronism is one of the most common causes of secondary hypertension. In recent years the prevalence has risen dramatically, from 1% to 14% of all hypertensive patients. This has been largely attributed to an increase in diagnosis. Primary aldosteronism is characterized by hypertension with or without hypokalemia and a high plasma aldosterone concentration (PAC) with a concurrent low plasma renin activity (PRA). The most common subtypes of primary aldosteronism are aldosterone-producing adenoma (42%) and bilateral idiopathic hyperaldosteronism (58%). Other less common subtypes (<1%) are glucocorticoid-remediable aldosteronism, and unilateral primary hyperplasia. Current treatment for primary aldosteronism relies on accurate subtype distinction and assessment of unilateral versus bilateral disease. Bilateral idiopathic hyperaldosteronism is best managed pharmacologically and improves with the use of aldosterone receptor antagonists. Combined treatment with sodium-channel blockers and calcium-channel blockers has also shown satisfactory results. Glucocorticoid-remediable aldosteronism responds well to treatment with low-dose glucocorticoids. Aldosterone producing adenoma and unilateral adrenal hyperplasia are appropriately treated with laparoscopic adrenalectomy. Following adrenalectomy blood pressure improves in 98% of these patients, but only about 33% require no further antihypertensive medication. Identifying the subgroups that will most benefit from adrenalectomy is paramount to formulating individual treatment strategies. In the past, treatment focused mainly on the correction of hypertension and electrolyte disturbances. Now, with accumulating evidence of the detrimental effects of aldosterone to the myocardium, vascular endothelium and kidneys, treatment also focuses on normalizing aldosterone levels or blocking aldosterone action at the receptor level. Therefore, it is essential to accurately identify the specific subtype of primary aldosteronism in order to select optimal treatment and to achieve successful patient outcomes.