Potassium-sparing diuretics

náhled|150px|chemická struktura spironolaktonu náhled|150px|Kalium-kanrenoát (Aldactone®) 125 mg v ampuli pro i. v. aplikaci náhled|150px|chemická struktura amiloridu náhled|150px|chemická struktura kalium-kanrenoátu Potassium-sparing diuretics act as aldosterone antagonists in the collecting duct and in the lower part of the distal tubule. It can be a direct antagonism – e.g. spironolactone acts as a blocker of the mineralocorticoid receptor. On the other hand, for example, amiloride inhibits the transport of Na+ by ion channels in the luminal membrane, thus reducing sodium resorption. This also reduces the loss of potassium into the urine, as the resorption of Na+ from the collecting ducts creates a negative electrical potential in their lumen, which facilitates the secretion of K+ and H+ into the urine.

Representatives
We rank among the main representatives:
 * and its active metabolite,

Indication
Increased mineralocorticoid effect due to primary or secondary aldosteronism. Secondary aldosteronism results from heart failure, liver cirrhosis, nephrotic syndrome, and administration of thiazide and loop diuretics.

Adverse effects and toxicity

 * Hyperkalemia can reach life-threatening values. The risk of this complication is increased if the kidneys are affected or with simultaneous administration of drugs (beta-blockers, non-steroidal anti-rheumatic drugs or ACE inhibitors).
 * Hyperchloremic metabolic acidosis can be induced when H+ secretion is inhibited with simultaneous K+ secretion.
 * Gynecomastia – spironolactone.

Related articles

 * Diuretics
 * The renin-angiotensin-aldosterone system
 * Hypertension
 * Hypertensive crisis