Antihypertensives Test Prep and Practice Pearls; Part 3 – Aldosterone Antagonists and Vasodilators
Real Life Pharmacology - Pharmacology Education for Health Care Professionals
Eric Christianson, PharmD; Pharmacology Expert and Clinical Pharmacist
4.9 • 773 Ratings
🗓️ 25 December 2025
⏱️ 14 minutes
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Summary
Aldosterone antagonists, such as spironolactone and eplerenone, are potassium-sparing diuretics that block aldosterone at the mineralocorticoid receptor in the distal nephron. By reducing sodium and water reabsorption while conserving potassium, they play a key role in heart failure, resistant hypertension, and primary hyperaldosteronism. Clinically, they improve mortality in heart failure with reduced ejection fraction, making them much more than just “add-on” diuretics.
From a safety standpoint, the biggest concerns with aldosterone antagonists are hyperkalemia and renal function decline. These risks increase in patients with chronic kidney disease or when combined with ACE inhibitors, ARBs, or potassium supplements. Spironolactone can also cause endocrine-related adverse effects such as gynecomastia and menstrual irregularities, which is why eplerenone may be preferred in some patients.
Direct-acting vasodilators, most notably hydralazine and minoxidil, lower blood pressure by relaxing arteriolar smooth muscle and reducing systemic vascular resistance. Hydralazine is commonly used in heart failure in combination with nitrates, particularly in select patient populations, while minoxidil is reserved for severe, refractory hypertension due to its potency.
Despite their effectiveness, direct-acting vasodilators come with important clinical trade-offs. Reflex tachycardia and fluid retention are common, so they are typically prescribed alongside a beta blocker and a diuretic. Hydralazine is associated with drug-induced lupus, while minoxidil can cause significant edema and hypertrichosis, making careful patient selection and monitoring essential.
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Transcript
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| 0:00.0 | Hey everyone. Welcome back to the Real Life Pharmacology podcast. Thank you so much for listening. |
| 0:05.6 | As always, I am Eric Christensen pharmacist who's been in charge of this podcast for, I believe, it's almost seven or eight years now. |
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| 0:19.1 | I've done over 400 individual drugs now. |
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| 0:47.3 | All right. |
| 0:48.2 | While you're at real life pharmacology.com, go check out the 31 page PDF. |
| 0:54.0 | It's a top 200 study guide. Great refresher, great prepterology.com, go check out the 31-page PDF. It's a top 200 study guide. |
| 0:56.2 | Great refresher, great prep tool for exams and things of that nature as well. |
| 1:01.5 | So again, real-life pharmacology.com, we'll get that free 31-page PDF. |
| 1:05.9 | All right, we are going to cover aldosterone antagonists as well as direct acting vasodilators. |
| 1:15.6 | Continuing on our anti-hypertensive role here, first I'll cover aldosterone antagonist. |
| 1:24.4 | So if you remember what aldosterone does, probably the simplest way to put it, |
| 1:30.0 | and probably the easiest way for you to remember, is it allows the body to hold on to salt |
| 1:36.2 | and water, and it dumps potassium out of the body. |
| 1:41.0 | That's what aldosterone does. |
| 1:43.4 | So now when we're talking about |
| 1:44.5 | aldosterone antagonists think the exact opposite. They are going to cause the excretion |
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