Diuretics

Drugs > Cardiovascular System > Diuretics

Overview General pharmacology Examples of diuretics Therapeutic indications Side effects Cautions See also References

A diuretic is any drug that promotes the formation of urine by the kidney. When the rate of urination is elevated, there is a decrease in the volumes of water in the body and the circulating blood, thus reducing blood pressure. Diuretics can therefore be used to treat hypertension, heart failure and pulmonary and systemic oedema.

General pharmacology

There are three classes of diuretics that are commonly used to treat high blood pressure: high ceiling loop diuretics, thiazides and potassium-sparing diuretics. All three inhibit the reabsorption of blood sodium and water, which leads to increased urinary volume. But each works by affecting a different part of the kidneys, and each may have different uses, precautions and side effects.

Thiazides and high ceiling loop diuretics might lead to an excessive loss of potassium and this may cause weakness, confusion, or cardiac arrhythmia. Taking a potassium supplement will possibly be indicated. Otherwise the doctor might prescribe a potassium-sparing diuretic which is softer and which prevents excessive loss of potassium, and this in combination with a thiazide or a high ceiling loop diuretic.

Examples of diuretics

Examples of thiazide diuretics include:

• Chlorothiazide (Diuril).
• Hydrochlorothiazide (Apo-Hydro).
• Metolazone (Zaroxolyn).
• Indapamide (Lozol).

Examples of loop diuretics include:

• Bumetanide (Bumex).
• Ethacrynic acid (Edecrin).
• Furosemide (Lasix).
• Torsemide (Demadex).

Examples of potassium-sparing diuretics include:

• Amiloride (Midamor).
• Triamterene (Dyrenium).
• Eplerenone (Inspra).
• Spironolactone (Aldactone).

Therapeutic indications

Generally doctors recommend that most people suffering from high blood pressure and heart problems related to high blood pressure should try thiazide diuretics as the first choice of treatment. If diuretics alone are not enough to lower blood pressure, other medications such as beta blockers, angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers may be added.

Doctors also recommend diuretics to treat certain conditions such as:

• Hypertension (already discussed).
• Heart failure.
• Tissue swelling (oedema).
• Diabetes characterized by frequent urination (diabetes insipidus).
• Certain kidney disorders, such as kidney stones.
• Osteoporosis.
• Polycystic ovary syndrome.
• Male-pattern hair growth in women (female hirsutism).

Side effects

Although diuretics are considered generally safe, they do have some side effects. The most common one is increased urination, which occurs mostly with loop diuretics. This side effect usually gets better after a few weeks.

Common side effects of diuretics include:

• Increased urination (already discussed).
• Hyperkalemia, or too much potassium in the blood, which might occur with potassium-sparing diuretics.
• Hypokalemia, or too little potassium in the blood, which might occur when taking thiazide or loop diuretics.
• Hyponatremia, or low sodium in the blood.
• Increased cholesterol.
• Rash.
• Increased blood sugar.
• Joint disorders (gout).
• Impotence in men.
• Gynecomatia, or breast enlargement in men.
• Menstrual irregularities.

Cautions

People who take diuretics may also have little potassium in their blood (hypokalemia) if they take a thiazide diuretic, or too much potassium in their blood (hyperkalemia) if they take a potassium-sparing diuretic.

Major drug groups

  Cardiovascular System

Cardiovascular system

  ACE Inhibitors Beta Blockers Calcium Channel Blockers Centrally Acting Sympatholytics Diuretics Peripherally Acting Sympatholytics

References