What is allopurinol, and how does it work (mechanism of action)?
Allopurinol is used for treating
gout
caused by excessive levels of uric acid in the blood (hyperuricemia). It is a
xanthine oxidase inhibitor and is similar to febuxostat (Uloric). Uric acid is a
by product from the breakdown of certain proteins (purines) in the body by
enzymes called xanthine oxidases. Hyperuricemia occurs when the body produces
more uric acid than it can eliminate. The uric acid forms crystals in joints
(gouty arthritis) and tissues, causing inflammation and pain. Elevated blood uric
acid levels also can cause kidney disease and kidney stones.
Allopurinol prevents the production of uric acid by blocking the activity of the
enzymes that converts purines to uric acid. Uric acid levels usually begin to
fall within 2-3 days of starting treatment and return to their original levels
within 7-10 days after allopurinol is stopped. It may take several months of
therapy before attacks of gout are controlled. The FDA approved allopurinol in August 1966.
What brand names are available for allopurinol?
Zyloprim, Aloprim
Is allopurinol available as a generic drug?
Yes
Do I need a prescription for allopurinol?
Yes
What are the uses for allopurinol?
Allopurinol is used for preventing and/or treating acute
attacks of gout, erosive destructive gouty joint disease, uric acid deposits in
tissues (tophi), gouty kidney disease, and uric acid stones. Allopurinol also is
used to prevent elevation of blood uric acid in patients undergoing chemotherapy for the treatment of certain cancers and in patients with
recurrent calcium kidney stones and elevated uric acid levels.
What are the side effects of allopurinol?
Common side effects include:
QUESTION
Gout is a form of arthritis.
See Answer
What is the dosage for allopurinol?
The dose of allopurinol for treating gout is 200-600 mg daily
depending on severity. The dose for treating high uric acid blood levels due to
chemotherapy is 100-800 mg daily starting 1 or 2 days before chemotherapy. It
should be taken with food to avoid irritation of the stomach. In order to avoid
formation of kidney stones, patients should drink plenty of fluids while taking allopurinol.
Which drugs or supplements interact with allopurinol?
: Allopurinol increases blood levels of oral mercaptopurine
(Purinethol) and
azathioprine (Imuran) by reducing their breakdown in the body. Therefore,
the dose of mercaptopurine and azathioprine should be reduced in order to avoid
toxicity. There is an increased risk of skin
rash
in patients taking allopurinol in combination with penicillins. Allopurinol may
increase the effect of warfarin by reducing its breakdown.
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Is allopurinol safe to take if I’m pregnant or breastfeeding?
There are no adequate studies of allopurinol in pregnant women.
Allopurinol is excreted in breast milk. To avoid adverse effects in the infant,
nursing
mothers taking allopurinol should consider not breastfeeding.
What else should I know about allopurinol?
What preparations of allopurinol are available?
Tablets: 100, 300 mg; Powder for injection: 500 mg
How should I keep allopurinol stored?
Tablets should be stored at room temperature between 15 C to 25 C
(59 F to 77 F) and in a moisture proof, light- resistant container. Powder
should be stored from 20 C to 25 C (68 F to 77 F) and not refrigerated.