Diuretics Health Article

Definition

Diuretics are medicines that help reduce the amount of water in the body.

Purpose

Diuretics are used to treat the buildup of excess fluid in the body that occurs with some medical conditions such as congestive heart failure, liver disease, and kidney disease. Some diuretics are also prescribed to treat high blood pressure. Most of these drugs act on the kidneys to increase urine output. This reduces the amount of fluid in the bloodstream, which in turn lowers blood pressure.

Diuretics may be used in surgery to reduce blood pressure and swelling. Mannitol, an osmotic diuretic, may be used to reduce swelling in the brain, which may be necessary for some neurosurgical procedures.

Description

There are several types of diuretics, also called water pills:

• Loop diuretics, such as bumetanide (Bumex) and furosemide (Lasix), get their name from the loop-shaped part of the kidneys where they have their effect.
• Thiazide diuretics include such commonly used diuretics as hydrochlorothiazide (HydroDIURIL, Esidrix), chlorothiazide (Diuril), and chlorthalidone (Hygroton).
• Potassium-sparing diuretics prevent the loss of potassium, which is a problem with other types of diuretics; examples of potassium-sparing diuretics are amiloride (Midamor) and triamterene (Dyrenium).
• Osmotic diuretics keep water from being reabsorbed in the kidney. Mannitol, which is given by intravenous drip, is commonly used to reduce cerebral edema (swelling of the brain).
• Carbonic anhydrase inhibitors are another form of diuretic. While they cause water loss through the kidneys by changing the acidity of urine, their most common use is in treatment of glaucoma, an eye disease caused by increased pressure inside the eyeball. Acetazolamide (Diamox) is the most commonly used carbonix anhydrase inhibitor. Acetazolamide is given by mouth, but other drugs may be given as eye drops.

In addition, some medicines contain combinations of two diuretics. The brands Dyazide and Maxzide, for example, contain the thiazide diuretic hydrochlorothiazide with the potassium-sparing diuretic triamterene.

Some nonprescription (over-the-counter) medicines contain diuretics. However, the medicines described here cannot be bought without a physician's prescription. They are available in tablet, capsule, liquid, and injectable forms.