Spironolactone Versus Amiloride as an Add on Agent in Resistant Hypertension

Randomized Trial of Spironolactone Versus Amiloride as an Add on Agent in Resistant Hypertension

Joint National Committee 7 (JNC-7) defines resistant hypertension as a persistent elevation of blood pressure (BP) above goal - ≥ 140/90 mm Hg for the general hypertensive population or ≥ 130/80 mm Hg for persons with diabetes mellitus or chronic kidney disease - for at least three months despite treatment with three or more optimally dosed antihypertensive agents, including a diuretic. The exact prevalence of resistant hypertension is uncertain but may include 5-20% of hypertensive persons in primary care settings and 15-35% of the older, higher cardiovascular risk hypertensive patients incorporated into recent clinical trials of antihypertensive therapy. Observational studies demonstrate that patients with resistant hypertension experience a higher rate of cardiovascular and renal target organ damage such as left ventricular hypertrophy, microalbuminuria, and renal insufficiency and more cardiovascular disease (CVD) events than patients whose hypertension is well-controlled. Additionally, resistant hypertension patients may be subjected to the considerable expense of multiple office visits, diagnostic testing for secondary causes of hypertension, and referral to hypertension specialists. Because multiple factors can contribute to resistant hypertension, an explicit, sequential approach to evaluation and management is essential to optimize blood pressure, reduce cardiorenal morbidity and mortality, and avoid unnecessary expense. A number of observational studies have suggested the potential efficacy of both spironolactone and amiloride when added to a 3 drug antihypertensive regimen, but to date no randomized study has directly compared the two agents. The goal of this study is to determine whether spironolactone or amiloride is the more effective fourth agent to add to a three drug regimen in patients with resistant hypertension.

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Inclusion Criteria:

• Participants will be selected from a broad range of medical clinics at the Salt Lake City VA Medical Center and surrounding community based outpatient clinics (CBOCs).
• The participants will be referred to a resistant hypertension clinic by either their primary care provider or by a subspecialist. The referrals are made via a computerized system that is used in the Veterans Affairs Medical Center (VA) called Computerized Patient Record System (CPRS).
• Patients are referred if their blood pressure is above goal as defined by JNC 7 and they are on 3 antihypertensive medications with one of the agents being a diuretic.
• All patients age 18 -80 years old.

Exclusion Criteria:

• Patients that will be excluded from the study if they have had a documented adverse reaction to either spironolactone or amiloride.
• diagnosis of primary hyperaldosteronism
• inability to adhere to frequent laboratory monitoring
• estimated glomerular filtration rate (GFR) < 45 ml/min/1.73m2
• baseline serum potassium above 5.0 mEq/L
• type 4 renal tubular acidosis
• pregnancy
• heart failure that meets criteria for using either eplerenone or spironolactone
• current unstable renal function