Spironolactone for Hypertension

(SPIRO-First Trial)

This trial aims to determine if spironolactone, a medication for high blood pressure, outperforms other common treatments for individuals with low-renin hypertension. Researchers seek to assess the practicality of using this medication strategy in regular community health clinics. Participants will take either spironolactone or one of the standard treatments (such as amlodipine, candesartan, or hydrochlorothiazide) for 12 weeks to compare their effectiveness in lowering blood pressure. This trial suits adults whose high blood pressure is not well managed with their current treatment or who are not on any treatment. As a Phase 4 trial, it involves an FDA-approved treatment, aiming to understand its benefits for more patients.

If you are currently taking one antihypertensive medication, you may need to stop it for a 2-week period before starting the trial. Your primary care clinician will decide if it's safe for you to do so.

Research has shown that spironolactone is generally well-tolerated by people with high blood pressure and effectively lowers blood pressure in patients unresponsive to other treatments. In one study, the spironolactone group reported 24 side effects, similar to the 26 in the placebo group, suggesting that spironolactone's safety is comparable to a placebo.

However, spironolactone can affect kidney function. Some studies noted changes in kidney function tests, such as eGFR (a measure of kidney health), serum creatinine (a waste product filtered by the kidneys), and serum potassium levels. Participants should have these levels checked regularly during treatment.

Unlike standard treatments for hypertension, which often include medications like amlodipine, candesartan, and hydrochlorothiazide, spironolactone offers a unique approach by acting as a mineralocorticoid receptor antagonist. This means it blocks the action of aldosterone, a hormone that can increase blood pressure. Researchers are particularly excited about spironolactone because it targets resistant hypertension, providing an option for patients who do not respond well to the usual first-line therapies. Additionally, its role in managing fluid retention can be beneficial for certain patients, offering a dual-action benefit in treating hypertension.

Research has shown that spironolactone, which participants in this trial may receive, can help lower blood pressure in individuals whose high blood pressure remains uncontrolled with multiple medications. Studies have found that it can reduce the systolic blood pressure by 11 to 17 points and the diastolic by up to 6 points. It proves effective when added to other treatments for those with hard-to-control blood pressure. In some studies, spironolactone emerged as the best option for lowering blood pressure in these situations. This trial will also compare spironolactone to standard first-line antihypertensive therapies, including candesartan, hydrochlorothiazide, and amlodipine, to evaluate its effectiveness in treating high blood pressure.²⁶⁷⁸⁹