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What are Diuretics ?
Medications that promote the
excretion of urine to help the body get rid of excess water and
salt. Diuretics (colloquially called a water pill) are often
prescribed to help reduce excess fluid levels (extra-cellular
fluid, ECF) in the body, such as associated with chronic heart
failure, high blood pressure (hypertension) or certain kidney
(renal) or liver (hepatic) disorders. Diuretics help to remove
excess water from the body by increasing the amount that is
excreted as urine. They are often used as anti-hypertensive
drugs to dehydrate during a general edema. Caffeine, cranberry
juice and alcohol are all weak diuretics. Diuretics effective
for the treatment of edema have been available since the 16th
century. Mercurous chloride was known by Paracelsus to be
diuretic.
In 1930, Swartz discovered that the antimicrobial sulfanilamide
could be used to treat edema in patients with congestive heart
failure due to an increase in renal excretion of Na+. Today,
most modern diuretics were developed when side effects of
antibacterial drugs were noted, which included changes in urine
composition and output. Except for spironolactone, diuretics
were developed empirically, without knowledge of specific
transport pathways in the nephron. Chemically, diuretics are a
diverse group of compounds that either stimulate or inhibit
various hormones that naturally occur in the body to regulate
urine production by the kidneys. The primary therapeutic goal of
diuretic use is to reduce edema by reducing the ECF volume.
Kidneys control the extra-cellular fluid (ECF) volume by
adjusting Sodium Chloride (NaCl) and water excretion. Each day
the kidney filters more than 22 moles of Sodium. To maintain the
balance of Sodium Chloride approximately 3 lbs. of NaCl must be
reabsorbed by the renal tubules on a daily basis.
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The body maintains blood pressure at
the expense of ECF volume. When NaCl intake is greater than
output, congestive heart failure or renal failure, edema
develops. Diuretics primarily prevent Na+ entry into the tubule
cell. It is necessary for diuretics to get into the tubule fluid
in order to be effective. Once a diuretic enters the tubule
fluid, the nephron site at which it acts determines its effect.
In addition, the site of action also determines which
electrolytes, other than Na+, will be affected. All diuretics
except spironolactone exert their effects from the luminal side
of the nephron. Mannitol does this by filtration at the
glomerulus. All other diuretics (except spironolactone) are
tightly protein bound and undergo little filtration.
Examples of Diuretics
There are three types of diuretics: thiazide, loop and
potassium-sparing. Each works by affecting a different part of
your kidneys, and each may have different uses, side effects and
precautions. The suitability of a particular diuretic depends on
the health and condition of the patient being treated. |
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Thiazide diurectics inhibit Na+ and
Cl- transport in the cortical thick ascending limb and early
distal tubule. They have a milder diuretic action than do the
loop diuretics because this nephron site reabsorbs less Na+ than
the thick ascending limb. In addition if glomerular filtration
rate falls, less fluid reaches the distal tubule and thiazides
may only have a small impact on Na+ and water excretion. These
compounds then are relatively ineffective in renal
insufficiency. Thiazides can induce a volume contraction, which
leads to enhanced proximal tubule reabsorption of fluid and
solutes. Use of thiazides results in an increased absorption of
Ca2+ and uric acid by the proximal tubule, ultimately leading to
reduced excretion of Ca2+ and uric acid.
Side Effects and Cautions
In general, potential side effects of diuretics include
increased urination, weakness, dizziness, impotence, dehydration
and, depending on the type of diuretic, potassium decrease or
increase, or sodium decrease.
What Are
the Side Effects ?
Frequent urination: This may
last for up to four hours after each dose. If you are taking two
diuretic doses each day, take the second dose no later than late
afternoon so you can sleep through the night.
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Extreme
tiredness or weakness: These effects should decrease
as your body adjusts to the medication. Call your doctor or
nurse if these symptoms persist, since these symptoms could mean
your medication dose needs to be adjusted.
Muscle cramps or weakness:
Be sure that you are taking your potassium supplement correctly,
if prescribed. Contact your doctor or nurse if these symptoms
persist.
Thirst: Try sucking on
sugarless hard candy. Contact your doctor or nurse if you have
extreme thirst, which could be a sign of dehydration.
Dizziness, light-headedness:
Try rising more slowly when getting up from a lying or sitting
position. Blurred vision, confusion, headache, increased
perspiration (sweating) and restlessness: If these effects are
persistent or severe, contact your doctor or nurse. |
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Dehydration:
Signs include dizziness, extreme thirst, excessive dryness of the
mouth, decreased urine output, dark-colored urine, or constipation.
If these symptoms occur, don't assume you need more fluids--call
your doctor or nurse.
Skin rash: Stop taking the
medication and contact your doctor or nurse right away. Loss of
appetite, nausea, vomiting or muscle cramps: Be sure that you are
taking your potassium supplement correctly, if prescribed. Contact
your doctor or nurse if these symptoms persist. Fever, sore throat,
cough, ringing in the ears, unusual bleeding or bruising, rapid and
excessive weight loss: Contact your doctor or nurse right away.
Examples of thiazide diuretics include
Chlorothiazide (Diuril)
Indapamide (Lozol)
Metolazone (Zaroxolyn)
The common conditions for which
diuretics are prescribed by Doctors to prevent, treat or improve are
Certain kidney disorders, such as kidney stones
High blood pressure
Congestive heart failure
Edema
Polycystic ovary syndrome
Diabetes insipidus
Female hirsutism
Osteoporosis
Some diuretics may require you to avoid
or include certain foods in your diet. Follow your doctor's advice,
which may include
Following a low-sodium diet
Taking a potassium supplement or including high-potassium foods
such as bananas and orange juice if you are losing potassium. Talk
to your doctor about your level of potassium intake
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Article Contributed By: Sukanya
Banerjee
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