WordNet

a light soft silver-white metallic element of the alkali metal group; oxidizes rapidly in air and reacts violently with water; is abundant in nature in combined forms occurring in sea water and in carnallite and kainite and sylvite (同)K, atomic number 19

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ポタシウム,カリウム(金属元素;化学記号はK)
禁約な,つましい,控え目な
排尿促進の,利尿の / 利尿剤

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2017/10/17 22:35:35」(JST)

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Structural formulae of the potassium-sparing diuretics. Click to enlarge.

Potassium-sparing diuretics are diuretic drugs that do not promote the secretion of potassium into the urine.^[1]

They are used as adjunctive therapy, together with other drugs, in the treatment of hypertension and management of congestive heart failure. However, at low doses the use of potassium-sparing diuretics has not been found to produce a clinically significant reduction in blood pressure.^[2]

Indications

Potassium-sparing diuretics are generally used in combination with other diuretic drugs (e.g. loop diuretics) that would otherwise tend to lower the potassium levels to potentially dangerous low levels (hypokalemia). The combination therefore helps maintain a normal reference range for potassium.

Adverse effects

On their own this group of drugs may raise potassium levels beyond the normal range, termed hyperkalemia, which risks potentially fatal arrhythmias.

Mechanism of action

The potassium-sparing diuretics are competitive antagonists that either compete with aldosterone for intracellular cytoplasmic receptor sites, or directly block sodium channels (specifically epithelial sodium channels (ENaC) by amiloride). The former prevents the production of proteins that are normally synthesized in reaction to aldosterone. These mediator proteins are not produced, and so stimulation of sodium-potassium exchange sites in the collection tubule does not occur. This prevents sodium re-absorption and potassium and hydrogen ion secretion.^[3]

Chemical structure

Potassium-sparing diuretics do not share any obvious chemical similarities, except for the steroid-structure of the aldosterone antagonists. Those in clinical use include:

Epithelial sodium channel blockers
- Amiloride
- Triamterene
Aldosterone antagonists (mostly spirolactones):
- Spironolactone
- Eplerenone

Other diuretics

While not classically considered potassium-sparing diuretics, ACE inhibitors (ACEi) and angiotensin receptor blockers (ARB) are anti-hypertensive drugs with diuretic effects that decrease renal excretion of potassium.^[4] They work by inhibiting either the production (ACEis) or effects (ARBs) of angiotensin 2. This results in a decrease in aldosterone release, which causes potassium-sparing-diuretic-like effects similar to those of the aldosterone antagonists, spironolactone and eplerenone.

References

^ "diuretic" at Dorland's Medical Dictionary
^ Heran BS, Chen JMH, Wang JJ, Wright JM. Blood pressure lowering efficacy of potassium-sparing diuretics (that block the epithelial sodium channel) for primary hypertension. Cochrane Database of Systematic Reviews 2012, Issue 11. Art. No.: CD008167. DOI: 10.1002/14651858.CD008167.pub3. SEARCH Go Search >Medical Terms (MeSH) >Search Manager > ARTICLE TOOLS Save to My Profile Export Citation for this Article E-mail Link to this Article Submit Comments Request Permissions Share|
^ Pharmacology. 2nd ed. Harvey, Champe.
^ "ACE INHIBITORS; ARBS/POTASSIUM SPARING DIURETICS". Drug-Drug Interaction. JIRDC. Retrieved 17 March 2012.

External links

Potassium Sparing Diuretics at the US National Library of Medicine Medical Subject Headings (MeSH)

UpToDate Contents

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4. Use of mineralocorticoid receptor antagonists in heart failure with reduced ejection fraction
5. 原発性アルドステロン症の治療 treatment of primary aldosteronism

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