Diuretics, or "water pills," work in tandem with other drugs used to relieve symptoms of congestive heart failure, which is commonly called referred to as CHF. Diuretics relieve congestive symptoms and extremity edema seen in patients with stage 'C' or stage 'D' CHF, the classification system set forth by the American College of Cardiology. Some diuretics improve mortality rates in CHF patients.
Function
Ridding the body of excess volume is the goal of all diuretics. More than one way exists to reach this goal. Each class of diuretics works by a different method. However, each drug acts in some way on the bean-shaped organs that help maintain water regulation in the body--the kidneys.
Classes of Drugs
Loop diuretics are the most powerful diuretics. They act on a special loop-shaped portion of tubes located in the kidney. By causing sodium and chloride to release into the urine, water follows, relieving the body of excess fluid. Some common examples of loop diuretics are bumetanide (Bumex) and furosemide (Lasix).
Potassium sparring diuretics act on the distal tubes located in the kidney. Though they have different mechanisms, they work in a way that is similar to loop diuretics. Potassium sparring diuretics act to remove sodium from the body in exchange for potassium. Spironolactone (Aldactone), amiloride (Midamor) and triamterene (Dyrenium) are examples of potassium sparring drugs.
Thiazides work differently than both of the above classes. They work by inhibiting the hormone aldosterone. Aldosterone is released when the body detects low blood volume, as in CHF, when all the water has shifted from the blood into the extremities. The body interprets this as low volume status and signals the release of aldosterone. In turn, aldosterone retains sodium to increase volume. Thiazides prevent this from occurring. Examples of commonly used diuretics include hydrochlorothiazide (Esidrix), chlorothiazide (Diuril), and chlorthalidone (Hygroton).
Types of Use
Most diuretics can be administered orally. However, during periods of acute symptoms of congestive heart failure, it is necessary to use an intravenous route. This method is quicker and more efficient if a patient is in need of immediate relief from severe congestive symptoms. DailyMed lists bumetanide, furosemide and chlorothiazide as available for intravenous injection.
Safety and Side Effects
Each class of diuretics has its own side-effect profile. Within those classes are specific side effects. Most diuretics are tolerated well. The following are the most commonly reported:
Gastrointestinal symptoms (ie. pancreatitis, jaundice, anorexia), systemic allergic reactions (ie. vasculitis, nephritis) and central nervous system effects (ie. tinnitus, paresthesias, vertigo) are listed as the most common side effects associated with loop diuretics.
Potassium-sparring drugs are known to have the benefit of retaining potassium and increasing mortality rates in heart failure patients. In addition to benefits, their most common side effects reported by the DailyMed, the online medications library published by the National Institutes of Health, include headache, nausea, and vomiting. There are no known reported cardiovascular effects.
Thiazides are associated with general weakness, cardiovascular symptoms (ie. low blood pressure), gastrointestinal symptoms (ie. pancreatitis, jaundice, anorexia) and hematologic symptoms (ie. anemia, low white and red blood cell counts).
Requires Chronic Management
CHF is typically a long-term disease. Once congestive symptoms are present, chronic management is needed. Diuretics are used daily in low doses to maintain low volume status and prevent congestive symptoms such as shortness of breath and fluid in the extremities. In the event that symptoms reoccur, larger doses are necessary and may even require hospitalization.
