high levels of calcium in the blood). They are also
given together with other drugs to treat edema of the
brain or lungs, conditions that require rapid diuresis.
Drugs classified as loop diuretics include furosemide
(Lasix), bumetanide (Bumex), ethacrynic acid (Ede-
crin), and torsemide (Demadex).
THIAZIDE DIURETICS.Thiazide diuretics are derived
from a chemical called benzothiadi(A)zene. Unlike the
loop diuretics, which work in the loop of Henle, thia-
zide diuretics work in a different structure called the
distal convoluted tubule, although they function in a
similar way to increase urine production by decreasing
the kidney’s reabsorption ofsodium and calcium.
They are not as strong as loop diuretics and have
fewer adverse effects.
Thiazide diuretics are commonly prescribed to
manage high blood pressure because they help to
dilate blood vessels as well as lower blood volume by
increasing urine output. They are also sometimes
given to patients with high levels of calcium in the
urine to prevent the formation of kidney stones and
lower the risk ofosteoporosis. They include such
drugs as hydrochlorothiazide (HydroDiuril, Esidrix),
chlorothiazide (Diachlor, Diuril), and chlorthalidone
(Hygroton, Hylidone).
POTASSIUM-SPARING DIURETICS.Potassium-sparing
diuretics include such drugs as amiloride (Midamor)
and triamterene (Dyrenium). They are usually given
together with loop diuretics in treating CHF or high
blood pressure to prevent the patient’s potassium level
from falling too low. They work by decreasing sodium
reabsorption in the collecting tubules of the kidneys.
There are two formulations that combine the
potassium-sparing diuretic triamterene with the thia-
zide diuretic hydrochlorothiazide in one pill—Maxzide
and Dyazide—thus simplifying the patient’s dosage
schedule.
OSMOTIC DIURETICS.Osmotic diuretics are sub-
stances that cannot be reabsorbed in the kidney and
so increase urine volume by osmosis. The most com-
monly used osmotic diuretic is mannitol, a sugar alco-
hol or polyol that is also added to sugar-free candies,
mouthwashes, and similar products as an artificial
sweetener. Mannitol (Osmitrol) is given intravenously
to patients with glaucoma to lower fluid pressure
inside they eyeball, and to patients with acute kidney
failure following cardiovascular surgery.
Until early 2007, high-dose mannitol was recom-
mended as treatment to reduce fluid accumulation
inside the skull in cases of head trauma, on the basis
of randomized trials conducted by a neurosurgeon inBrazil who committed suicide in 2005. His papers on
the use of mannitol in head surgery were called into
question in late 2006; neither his former coauthors nor
the journal editors who published his studies have
been able to verify his data; and the university he
claimed as his affiliation has never employed him.
CARBONIC ANHYDRASE INHIBITORS.Carbonic anhy-
drase inhibitors are a class of diuretics that increase
waterloss through the kidneys by changing the acidity
of urine. Their most common use, however, is to treat
glaucoma by lowering the fluid pressure inside the
eyeball. The most common diuretic in this group,
acetazolamide (Diamox), is also used as an anticon-
vulsant (drug given to prevent seizures). Other car-
bonic anhydrase inhibitors include dichlorphenamide
(Daranide) and methazolamide (Neptazane).Nonprescription diuretics
Nonprescription diuretics are often used by diet-
ers to flush water from the body in the belief that this
practice will promote rapid weight loss. According to
the Centers for Disease Control and Prevention
(CDC), 1% of adult male dieters in the United States
and 2% of adult women have used over-the-counter
diuretics as part of weight loss attempts.
CAFFEINE.Caffeine is a xanthine alkaloid found
naturally in coffee beans, tea leaves, kola nuts, cocoa
beans, and a few other plants. It is well known as a
central nervous system (CNS) stimulant, enjoyed in
brewed coffee, tea, hot chocolate, cola beverages, and
energy drinks. It is also available in tablet form as an
over-the-counter stimulant in such compounds as
NoDoz. Caffeine is broken down in the liver to three
substances, one of which is theobromine, which acts as
a diuretic and increases urine volume. Some dieters
drink coffee as much for its diuretic effects as for its
effectiveness is counteracting the fatigue that often
accompanies low-calorie diets.
HERBAL PREPARATIONS.Naturopaths and other
practitioners of alternative medicine often recommend
certain herbal preparations, including herbal teas, as diu-
retics available without a prescription. Herbs commonly
recommended for their diuretic qualities include uva ursi,
dandelion, hydrangea, parsley, butcher’s broom, buchu,
juniper, horsetail, buckthorn, and asparagus.
ALCOHOL.Beverage alcohol (ethanol) is known to
have a diuretic effect; in fact, many of the symptoms of
an alcohol hangover, such as headache, nausea, and
diarrhea, are related to thedehydrationresulting from
alcohol intoxication. Many weight-reduction diets
(theMediterranean dietbeing a notable exception)
forbid alcohol because it contains more calories thanDiuretics and diets