Potassium-sparing diuretic

Potassium-sparing diuretic refers to diuretic drugs that do not promote the secretion of potassium into the urine. They are used as adjunctive therapy, together with other drugs, in the treatment of hypertension and management of congestive heart failure.

Mechanism of action
Potassium-sparing diuretics decrease sodium reabsorption at collecting tubules, inducing diuresis; decrease activity of aldosterone at collecting tubules.

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.

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

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:
 * Amiloride
 * Triamterene
 * Aldosterone antagonists:
 * Spironolactone
 * Eplerenone