Diuretics lower blood pressure and decrease peripheral and pulmonary edema in congestive heart failure and renal or liver disorders by inhibiting sodium and water reabsorption from the kidney tubules resulting in increased urine flow (diuresis).

Most sodium and water reabsorption occurs throughout the renal tubular segments. Diuretics affect one or more of these segments. Every one and one-half hours the kidneys (glomeruli) clean the body's extracellular fluid (ECF).

Small particles—such as electrolytes, drugs, glucose, and waste products from protein metabolism—are filtered in the glomeruli during this process. Sodium and water are the largest filtrate substances. Larger products—such as protein and blood—are not filtered with normal renal function. Instead, they remain in the circulation.

Nearly all filtered sodium is reabsorbed. Half occurs in the proximal tubules, approximately 40% in the loop of Henle, about 7% in the distal tubules, and the remaining in the collecting tubules.

Diuretics, such as Mannitol, that act on the tubules closest to the glomeruli have the greatest effect in causing sodium loss in the urine (natriuresis).

Diuretics have an antihypertensive effect by promoting sodium and water loss. They block sodium and chloride reabsorption causing a decrease in fluid volume, a lowering of blood pressure, and a decrease of edema. If sodium is retained, water is also retained in the body and blood pressure increases.

Many diuretics cause loss of other electrolytes, including potassium, magnesium, chloride, and bicarbonate. The diuretics that promote potassium excretion are classified as potassium-wasting diuretics. Potassium-sparing diuretics promote the reabsorption of potassium. Combination diuretics have been marketed that have both actions.

There are five categories of duretics that remove water and sodium.

Thiazide and thiazide-like diuretics

Thiazide diuretics include: chlorothiazide (Diuril), hydrochlorothiazide (HydroDIURIL, HCTZ), bendroflumethiazide (Naturetin), benzthiazide Aquatag, (Hydrex), hydroflumethiazide (Saluron, Diucardin); methychlothiazide (Aquatensen, Enduron), Polythiazide (Renese-R), trichlormethiazide (Metahydrin, Naqua); Thyzaide-like diuretics: chlorthalidone (Hygroton), indapamide (Lozol), metolazone (Zaroxolyn), and quinethazone (Hydromox).

Loop or high-ceiling diuretics

Loop or high-ceiling diuretics include bumetanide (Bumex), ethacrynic acid (Edecrin), furosemide (Lasix), and toresemide (Demadox).

Osmotic diuretics

Osmotic diuretics include Mannitol and urea (Ureaphil).

Carbonic anhydrase inhibitors

Carbonic anhydrase inhibitors include acetazolamide (Diamox), dichlor-phenamide (Darnide, Oratrol), and methazolamide (Neptazane).

Potassium-sparing diuretics

Potassium-sparing diuretics include amiloride HCl (Midamor); spironolactone (Aldactone), and triamterene (Dyrenium). Combination diuretics include: amiloride HCl and hydrochlorothiazide (Moduretic); spironolactone and hydrochlorothiazide (Aldactazide), and triamterene and hydrochlorothiazide (Dyazide, Maxzide).

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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