Midamor (Amiloride Hydrochloride) - Summary

MIDAMOR SUMMARY

Amiloride HCl, an antikaliuretic-diuretic agent, is a pyrazine-carbonyl-guanidine that is unrelated chemically to other known antikaliuretic or diuretic agents.

MIDAMOR is indicated as adjunctive treatment with thiazide diuretics or other kaliuretic-diuretic agents in congestive heart failure or hypertension to:

1. help restore normal serum potassium levels in patients who develop hypokalemia on the kaliuretic diuretic
2. prevent development of hypokalemia in patients who would be exposed to particular risk if hypokalemia were to develop, e.g., digitalized patients or patients with significant cardiac arrhythmias.

The use of potassium-conserving agents is often unnecessary in patients receiving diuretics for uncomplicated essential hypertension when such patients have a normal diet. MIDAMOR has little additive diuretic or antihypertensive effect when added to a thiazide diuretic.

MIDAMOR should rarely be used alone. It has weak (compared with thiazides) diuretic and antihypertensive effects. Used as single agents, potassium sparing diuretics, including MIDAMOR, result in an increased risk of hyperkalemia (approximately 10% with amiloride). MIDAMOR should be used alone only when persistent hypokalemia has been documented and only with careful titration of the dose and close monitoring of serum electrolytes.

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NEWS HIGHLIGHTS

Published Studies Related to Midamor (Amiloride)

Blood pressure-lowering efficacy of amiloride versus enalapril as add-on drugs in patients with uncontrolled blood pressure receiving hydrochlorothiazide. [2008.10]
A large proportion of patients with hypertension need a second drug to reach satisfactory control of blood pressure (BP), but there are few well-designed controlled trials comparing the efficacy of drugs added as a second option. In a double-blind randomized clinical trial, 82 patients with uncontrolled BP, receiving hydrochlorothiazide 25 mg daily, were selected to receive amiloride 2.5-5 mg/day (n = 39) or enalapril 10-20 mg/day (n = 43)...

Lithium-induced nephrogenic diabetes insipidus: renal effects of amiloride. [2008.09]
BACKGROUND AND OBJECTIVES: Polyuria, polydipsia, and nephrogenic diabetes insipidus have been associated with use of psychotropic medications, especially lithium... CONCLUSIONS: By inference, amiloride-induced reduction of lithium uptake in the principal cells of the collecting duct improves responsiveness to AVP-stimulated translocation of AQP2 to the apical membrane of the principal cells.

Lithium-induced Nephrogenic Diabetes Insipidus: Renal Effects of Amiloride. [2008.07.02]
BACKGROUND AND OBJECTIVES: Polyuria, polydipsia, and nephrogenic diabetes insipidus have been associated with use of psychotropic medications, especially lithium... CONCLUSIONS: By inference, amiloride-induced reduction of lithium uptake in the principal cells of the collecting duct improves responsiveness to AVP-stimulated translocation of AQP2 to the apical membrane of the principal cells.

The Spironolactone, Amiloride, Losartan, and Thiazide (SALT) double-blind crossover trial in patients with low-renin hypertension and elevated aldosterone-renin ratio. [2007.07.17]
CONCLUSIONS: In hypertensive patients with a low plasma renin but normal K+, bendroflumethiazide 5 mg was as effective as spironolactone 100 mg in lowering blood pressure, despite patients being selected for a previous large fall in blood pressure on spironolactone. Because this result differs from that expected in primary hyperaldosteronism, our finding argues against low-renin hypertension including a large, undiagnosed pool of primary hyperaldosteronism. However, spironolactone was the more effective natriuretic agent, suggesting that inappropriate aldosterone release or response may still contribute to the Na+ retention of low-renin hypertension.

Aspirin or amiloride for cerebral perfusion defects in cocaine dependence. [2003.08.20]
Cocaine dependent (CD) patients have regional cerebral blood flow (rCBF) deficits that may be related to occlusion of blood vessels by vasoconstriction and abnormal platelet aggregation. This study determined whether aspirin, which reverses platelet aggregation, or amiloride, a vasodilator, significantly reversed this rCBF hypoperfusion...

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Clinical Trials Related to Midamor (Amiloride)

The Influence of Rosiglitazone on the Diuretic Effect of Furosemide and Amiloride [Active, not recruiting]
Thiazolidinedionederivates (TZD’s) are Peroxisome-Proliferator-Activated-Receptor-γ agonists (PPARγ-agonists) and enhance insulin sensitivity. One of the side effects, however, is the fact that subjects treated with these drugs seem to be more prone to fluid retention. The precise mechanism of rosiglitazone-related fluid retention is unknown, but it is clear that either primary or secondary renal sodium retention is part of the mechanism. Furthermore in observational studies, TZD-related oedema seems to be resistant to loop diuretic therapy. The recent finding that rosiglitazone induces upregulation of the epithelial sodium channel (ENaC) in the kidney could be the explanation for TZD-related fluid retention and the observed resistance to loop diuretics. In the present human in-vivo study the following hypothesis will be tested:

Rosiglitazone treatment stimulates the activity of ENaC in the distal nephron, which enhances the natriuretic effect of amiloride and decreases the natriuretic effect of furosemide in parallel.

Spironolactone Versus Amiloride as an Add on Agent in Resistant Hypertension [Not yet recruiting]
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.

Efficacy of Amiloride and Hypertonic Saline in Cystic Fibrosis [Completed]
The purpose of this research study is to determine whether the combination of inhaled amiloride and a concentrated salt solution is better than the salt solution itself for cystic fibrosis (CF) patients. In CF, airway secretions are thick and dehydrated. Many patients use inhaled salt solutions to help draw water into their secretions so that they are easier to get rid of with chest physiotherapy (“chest PT”) and cough. Unfortunately, these salt solutions are reabsorbed very quickly by the airways, so the beneficial effects may not last very long. In the hopes of prolonging their effects, the drug amiloride could be used in combination to slow salt and water reabsorption from airways. Amiloride is a medication that has been given by mouth for high blood pressure for many years. It is possible that the combination of salt solutions and inhaled amiloride may significantly improve the clearance of secretions in CF, which would be expected to improve lung function in CF.

Amiloride Solution and Tobramycin Solution for Inhalation for the Eradication of Burkholderia Dolosa in Patients With Cystic Fibrosis [Active, not recruiting]
The purpose of this research study is to determine if multiple doses of two inhaled drugs will help Cystic Fibrosis patients whose lungs are infected with a bacteria called Burkholderia dolosa. The names of these drugs are tobramycin solution for inhalation and amiloride solution for inhalation. Currently, treating patients with Burkholderia dolosa infections is challenging because the bacteria is resistant to antibiotics. Therefore, researchers are looking for drugs which, when taken with an antibiotic, will help the antibiotic to work more effectively.

Antihypertensive Effectiveness of the Associations of Hydrochlorothiazide and Amiloride and Hydrochlorothiazide and Enalapril [Completed]
The majority of hypertensive patients require antihypertensive associations to control their blood pressure. Most of clinical trials don’t compare different associations using Hydrochlorothiazide 25 mg as the standard initial therapy and compare the associations using doses that are not equivalent.

This randomized trial where patients and investigators are blinded and compares the effectiveness two associations: Hydrochlorothiazide and Amiloride and Hydrochlorothiazide and Enalapril.

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