Kalium-sparing diuretics

Kalium-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 – for example, spironolactone acts as a blocker of the mineralocorticoid receptor. In contrast, e.g. amiloride inhibits Na+ transport to ionic channels in the luminal membrane, thus reducing sodium resorption. This also reduces the loss of potassium in the urine, as resorption of Na+ from the collection ducts creates a negative electrical potential in their lumen, which facilitates the secretion of K+ and H+ into the urine.

Representatives
The main representatives include:
 * spironolactone, and its active metabolite, kalium-canrenoate
 * amiloride

Indications
Increased mineralocorticoid effect due to primary or secondary aldosteronism. Secondary aldosteronism is a consequence of heart failure, hepatic cirrhosis, nephrotic syndrome and the administration of thiazide and loop diuretics.

Side effects and toxicity

 * Hyperkalemia can also reach life-threatening levels. The risk of this complication is intensified if the kidneys are affected or with the simultaneous administration of drugs (beta-blockers, nonsteroidal antirheumatics or ACE inhibitors).
 * Hyperchloremic metabolic acidosis can be provoked when inhibiting secretion H + under simultaneous K + secretion..
 * Gynecomastia – spironolactone.

Related articles

 * Diuretics
 * Renin-angiotensin-aldosterone system
 * Hypertension
 * Hypertensive crisis