What is metolazone, and how does it work (mechanism of action)?
Metolazone is a diuretic ("water pill") used
in the treatment of high blood pressure and fluid accumulation. It works by
blocking salt and fluid retention by the kidneys, thereby increasing urinary
output of salt and water (diuresis). Although it is not a true thiazide,
metolazone is chemically related to the thiazide class of diuretics (for
example,
chlorthalidone
[Hygroton], hydrochlorothiazide), and works in a similar manner. Zaroxolyn
is the original formulation of metolazone, and Diulo is similar. The absorption
of these two drugs is relatively incomplete. Mykrox has more complete
absorption. Therefore, less Mykrox needs to be given to have the same effects as
a larger dose of Zaroxolyn or Diulo. Metolazone was approved by the FDA in 1973.
What brand names are available for metolazone?
Zaroxolyn
Is metolazone available as a generic drug?
Yes
Do I need a prescription for metolazone?
Yes
What are the side effects of metolazone?
Metolazone generally is well tolerated. Common side effects of metolazone are:
- Hypokalemia (low blood potassium),
- hyponatremia
- (low blood sodium), and
- hypomagnesemia (low blood magnesium).
- Hypercalcemia (high blood calcium)
About 1 out of every 10 patients report dizziness,
lightheadedness, and headache.
Fatigue has been reported in 1 out of every 25
patients. About 1 out of every 50 patients reports:
- nausea,
- vomiting,
- abdominal pain, or
- constipation.
Thiazide diuretics, which are chemically related to
metolazone, are known to increase the amount of uric acid in the blood.
Precipitation of gout (which is associated with high uric acid) is rare.
Metolazone can increase blood sugar in people with
diabetes.
QUESTION
Salt and sodium are the same.
See Answer
What is the dosage for metolazone?
The recommended dose is 2.5 to 5 mg for hypertension and
2.5-20 mg for treating edema.
Which drugs or supplements interact with metolazone?
Metolazone can reduce blood potassium and magnesium
levels. This is especially true in patients who also are taking "loop" diuretics
such as furosemide (Lasix), bumetanide (Bumex), and torsemide (Demadex ). Low
potassium and magnesium levels can lead to
heart rhythm abnormalities,
especially in patients taking digoxin (Lanoxin). Metolazone reduces excretion of
lithium
(Lithobid, Eskalith) by the kidneys and can lead to lithium toxicity in patients receiving
lithium. Steroids (for example, hydrocortisone) and
nonsteroidal
anti-inflammatory agents (NSAIDs) such as ibuprofen (Motrin), naproxen (Naprosyn),
and nabumetone (Relafen) can reduce the effectiveness of metolazone by
interfering with the excretion of salt and water.
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Is metolazone safe to take if I’m pregnant or breastfeeding?
Metolazone should not be used
during pregnancy unless
absolutely necessary.
Metolazone is excreted in
breast-milk. Intense diuresis using metolazone may reduce the production of milk. Otherwise
metolazone is considered safe to use during nursing if required by the mother.
What else should I know about metolazone?
What preparations of metolazone are available?
Tablets: 2.5, 5, and 10 mg.
How should I keep metolazone stored?
Tablets should be stored at room temperature, 15 C – 30 C (59 F – 86 F).