How Do Potassium-Sparing Diuretics Work?

Diuretics also known as water pills are a class of drugs that cause diuresis (increased production of urine by the kidneys). Diuretics are drugs that work on the kidneys to remove electrolytes such as sodium and chloride from the body in the urine. These electrolytes draw water along with them; thus, excess water also gets eliminated in the urine. They are used to treat conditions associated with the presence of excess sodium and water in the body such as hypertension and fluid overload in the body that may damage major organs such as the heart and cause edema (accumulation of fluid in the body tissues causing swelling, usually seen due to damage to the small vessels).

Potassium-sparing diuretics are drugs that cause the excretion of sodium and water while preventing the loss of potassium in the urine. There are several drugs in this class, and each has a different mechanism of action.

• Sodium channel inhibition: some drugs work by inhibiting sodium channels on the distal part of the nephron, distal tubule, and collecting ducts where the sodium is reabsorbed. As these channels are blocked, the uptake of sodium is blocked and transepithelial potential is not generated; thus, the excretion of potassium is decreased.
• Aldosterone antagonism: aldosterone is a hormone that increases the reabsorption of sodium and water. These drugs inhibit aldosterone activity by binding to aldosterone receptors present on the collecting ducts and decrease the reabsorption of sodium and water.

Potassium-sparing diuretics are used for:

• Hypertension (high blood pressure)
• Congestive heart failure (the heart cannot pump enough blood that the body needs)
• Edematous conditions (swelling of the body caused by the accumulation of excess fluid)
• Primary aldosteronism or Conn’s syndrome (excess aldosterone production by the adrenal gland)
• Secondary aldosteronism (increase in production of aldosterone caused by conditions such as heart failure and decrease in renal flow)
• Prevention of hypokalaemia (low potassium levels in the blood) occurring when other diuretics are used
• Hirsutism (increase in the growth of facial hair in females)
• Polycystic ovarian syndrome

The side effects associated with potassium-sparing diuretics include:

• Hyperkalemia (increased levels of potassium in the blood)
• Nausea and vomiting
• Abdominal discomfort
• Headache
• Drowsiness
• Confusion
• Ataxia (loss of control on bodily movements due to lack of coordination between muscles and brain)
• Kidney stones
• Gynecomastia (enlargement of breasts in males)
• Impotence
• Hyperchloremic metabolic acidosis (caused by loss of bicarbonate)
• Menstrual irregularities
• Hypersensitivity reaction

The information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of potassium-sparing diuretics drugs include:

• Aldactone
• Amiloride (Midamor)
• Spironolactone (CaroSpir)
• Triamterene (Dyrenium)