Potassium-sparing diuretics are diuretics which do not promote the secretion of potassium into the urine; thus, potassium is retained and not lost as much as with other diuretics. The term "potassium-sparing" refers to an effect rather than a mechanism or location; nonetheless, the term almost always refers to two specific classes that have their effect at similar locations: (1) Aldosterone antagonists; spironolactone, aldosterone competitive antaagonist, prevents aldosterone from entering the principal cells, preventing sodium reabsorption. Similar agents are eplerenone and potassium canreonate. (2) Epithelial sodium channel blockers: amiloride and triamterene.