What is a potassium-sparing diuretic?

Potassium-sparing diuretics act in the distal tubule, inhibiting sodium reabsorption by exchange with potassium, directly on cells (triamterene, amiloride) or by antagonizing aldosterone.

Potassium-sparing diuretics reduce potassium excretion and increase sodium (salt) excretion, have the effect of reducing fluid volume without losing potassium in the body and are often prescribed for people with high blood pressure. low blood potassium levels, for example people who are taking other medicines that deplete the amount of potassium in the body.
Potassium-sparing diuretics include aldosterone antagonists (spironolactone) and non-aldosterone antagonists (amiloride). For spironolactone, a slow-acting drug, it takes 2-3 days after taking to have the maximum diuretic effect and lasts for another 2-3 days after stopping the drug. For amiloride, the effect begins about 2 hours after taking the diuretic, reaches a maximum about 6 - 10 hours and lasts for about 24 hours. You should take amiloride diuretics with food to reduce gastrointestinal side effects.

Potassium-sparing diuretics can cause undesirable effects including:
With the cardiovascular system, potassium-sparing diuretics lower blood pressure, edema, congestive heart failure, bradycardia. Body as a whole: Fatigue, headache, impotence, somnolence. Endocrine: Increased prolactin, gynecomastia, heavy milk flow, menstrual disorders, amenorrhea, bleeding after menopause. Gastrointestinal: Diarrhea, nausea. Skin: Erythema, rash, urticaria. Metabolism: Increased potassium - blood, decreased sodium - blood. Increased serum creatinine. Nervous: Muscle cramps/spasms, paresthesias. Blood: Agranulocytosis, thrombocytopenia. Usually, the adverse effects of potassium-sparing diuretics are mild and disappear when the drug is stopped. If you are treated with potassium-sparing diuretics for a long time, you need to be monitored for signs of electrolyte imbalance; If hyperkalemia occurs, the drug must be discontinued immediately. Nausea symptoms can be reduced by taking the drug after meals.

2.1 Indications for the use of potassium-sparing diuretics Ascites due to cirrhosis of the liver. Hepatic edema, renal edema, cardiac edema when other anti-edematous drugs are ineffective or unresponsive. As an adjunct to ACE inhibitors and other diuretics in the treatment of severe congestive heart failure Nephrotic syndrome; ascites due to malignancy. Primary hyperaldosteronism in inoperable cases. 2.2 Contraindications to diuretics Potassium-sparing diuretics are contraindicated in the following cases:
Severe or progressive renal failure; Severe liver disease; History of hyperkalemia or drug use, or drug hypersensitivity; People with hyperuricemia or gout; People with a history of kidney stones; Avoid potassium-sparing diuretics in severe cases because of the risk of respiratory or metabolic acidosis; Acidosis causes a rapid increase in serum potassium. Be careful with people who have to take potassium-sparing diuretics for a long time, monitor for signs of electrolyte imbalance, especially in cases with a history of heart failure, kidney disease, cirrhosis of the liver. You also need to periodically check the serum potassium level, especially in the elderly, people with cirrhosis, diabetes mellitus, impaired renal function or when the dose is changed. When laboratory tests show an increase in serum potassium levels, the drug should be stopped immediately.
For pregnant women, potassium-sparing diuretics should only be used during pregnancy when the potential benefits outweigh the risks to the fetus. For lactating women, do not use the drug during lactation because the drug is likely to be excreted in breast milk. If potassium-sparing diuretics are required, breast-feeding is not recommended.

If combined with potassium-sparing diuretics, angiotensin-converting enzyme inhibitors such as enalapril, captopril... there will be a high risk of hyperkalemia. Concomitant use of potassium-sparing diuretics with non-steroidal anti-inflammatory drugs, especially indomethacin, may be harmful to renal function. Concomitant use of potassium-sparing diuretics with potassium supplements or potassium-containing drugs such as benzylpenicillin potassium and other potassium-containing preparations is associated with an increased risk of hyperkalemia. Therefore, you need to avoid combining with these drugs in treatment. Lithium should not be used in combination with potassium-sparing diuretics due to decreased renal clearance of lithium and increased toxicity in the body.