|Trade names||Midamor, others|
|Bioavailability||Readily absorbed, 15–25%|
|Onset of action||2 hours (peak at 6–10 hours, duration ~24 hours)|
|Biological half-life||6 to 9 hours|
|Excretion||urine (20–50%), feces (40%)|
|Chemical and physical data|
|Molar mass||229.627 g/mol|
|3D model (JSmol)|
Amiloride, sold under the trade name Midamor among others, is a medication typically used with other medications to treat high blood pressure or swelling due to heart failure or cirrhosis of the liver. Amiloride is often used with a thiazide or other loop diuretic. It is taken by mouth. Onset of action is about two hours and it lasts for about a day.
Common side effects include high blood potassium, vomiting, loss of appetite, rash, and headache. The risk of high blood potassium is greater in those with kidney problems, diabetes, and those who are older. Amiloride is in the potassium-sparing diuretic family of medications. It works by increasing the amount of sodium and decreasing the amount of potassium released by the distal tubule of the kidney.
Amiloride was developed in 1967. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. In the United States the wholesale price of a month of medication is about 20.10 USD. In the United Kingdom a month of medication costs the NHS about 24 pounds.
- Common adverse effects:
Mechanism of action
Amiloride works by directly blocking the epithelial sodium channel (ENaC) thereby inhibiting sodium reabsorption in the late distal convoluted tubules, connecting tubules, and collecting ducts in the nephron. This promotes the loss of sodium and water from the body, but without depleting potassium. The drug is often used in conjunction with a thiazide diuretic to counteract the potassium-sparing effect. Due to its potassium-sparing capacities, hyperkalemia can occur. The risk of developing hyperkalemia is increased in patients who are also on ACE inhibitors, angiotensin II receptor antagonists, other potassium-sparing diuretics, or any potassium-containing supplements.
Amiloride has a second action on the heart, blocking Na+/H+ exchangers sodium–hydrogen antiporter 1 or NHE-1. This minimizes re-perfusion injury in ischemic attacks.
Amiloride also blocks the Na+/H+ antiporter on the apical surface of the proximal tubule cells, in the nephron, abolishing more than 80% of the action of angiotensin II on the secretion of hydrogen ions in proximal tubule cells.
Amiloride was also tested as treatment of cystic fibrosis, but it was revealed inefficient in vivo due to its short time of action, therefore longer-acting epithelial sodium channel (ENaC) inhibitors may prove more effective, e.g. benzamil.
Society and culture
It is on the World Health Organization's List of Essential Medicines, the most important medications needed in a basic health system.
Formulations and trade names
- Amiloride hydrochloride
- Midamor (U.S.)
- Co-amilozide (amiloride hydrochloride with hydrochlorothiazide)
- Co-amilofruse (amiloride hydrochloride with furosemide)
- Amiloride hydrochloride with cyclopenthiazide
- Amiloride hydrochloride with bumetanide
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- Progress in Drug Research/Fortschritte der Arzneimittelforschung/Progrés des recherches pharmaceutiques. Birkhäuser. 2013. p. 210. ISBN 9783034870948. Archived from the original on 2016-12-28.
- "WHO Model List of Essential Medicines (19th List)" (PDF). World Health Organization. April 2015. Archived (PDF) from the original on 13 December 2016. Retrieved 8 December 2016.
- "NADAC as of 2016-12-07 | Data.Medicaid.gov". Centers for Medicare and Medicaid Services. Archived from the original on 21 December 2016. Retrieved 28 December 2016.
- British national formulary : BNF 69 (69 ed.). British Medical Association. 2015. p. 90. ISBN 9780857111562.
- E-Facts and Comparisons: Amiloride Adverse effects 2016
- Loffing, Johannes; Kaissling, Brigitte (2003). "Sodium and calcium transport pathways along the mammalian distal nephron: from rabbit to human". Am J Physiol Renal Physiol. 284 (4): F628–F643. doi:10.1152/ajprenal.00217.2002. PMID 12620920.
- Walter F. Boron. Medical Physiology: A Cellular And Molecular Approaoch. Elsevier/Saunders. ISBN 1-4160-2328-3. page 875
- M G Cogan, Angiotensin II: a powerful controller of sodium transport in the early proximal tubule, Hypertension. 1990;15:451-458, doi:10.1161/01.HYP.15.5.451, "Archived copy". Archived from the original on 2016-09-19. Retrieved 2014-03-02.
- (Review)Pharmacological treatment of the biochemical defect in cystic fibrosis airways, H.C. Rodgers, A.J. Knoxhttp://erj.ersjournals.com/content/17/6/1314.full.pdf+html
- Hunt and Koltzenburg 2005 'The neurobiology of pain'
- "S5. Diuretics and masking agents - WADA". World Anti-Doping Agency. January 2016. Archived from the original on 27 September 2016. Retrieved 1 September 2016.