Home > Health Library > Xanthine Oxidase Inhibitors for Gout
are taken in tablet form (oral). They are taken
in low dosages at first. The dose may be adjusted if the uric acid
level is still not low enough.
Allopurinol and febuxostat
have different chemical structures, but they both prevent the release of a substance called
xanthine oxidase, which helps in the formation of uric acid. In treatment for
gout, these drugs block the production of
uric acid in the body.
Xanthine oxidase inhibitors may be prescribed to
prevent gout attacks. They also may be used because of:
Allopurinol may also be used for the prevention of kidney
disease in people going through treatment for cancer.
The dose of
xanthine oxidase inhibitors may need to be lower for people who have chronic kidney disease.
Allopurinol is not recommended for people who have a known sensitivity to
Xanthine oxidase inhibitors should not be started for the first time by
people who are still having symptoms caused by a gout attack.
Xanthine oxidase inhibitors lower the amount of
uric acid in the body.1 After the proper dose is
reached, the uric acid levels should return to normal. Your doctor will monitor
your uric acid level within one month of starting or changing a dose of
a xanthine oxidase inhibitor.
Treatment with xanthine oxidase inhibitors can reduce the size of
All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.
Here are some important things to think about:
Call 911 or other emergency services right away if you have:
Call your doctor if you have:
Common side effects of allopurinol include:
Common side effects of febuxostat include:
Drug Reference for a full list of side effects. (Drug Reference is not
available in all systems.)
Xanthine oxidase inhibitors interfere with many other medicines. They may
increase or decrease the levels of other medicines, which may raise the
toxicity of these medicines or reduce their effectiveness. Be sure your doctor knows about all prescription and over-the-counter medicines and dietary supplements you are taking.
Xanthine oxidase inhibitors should not be used until the
symptoms of a gout attack are gone. But if you are already taking one of these medicines,
continue to take it (even during an attack).
Gout attacks may
increase at first for some people who take allopurinol. To avoid this, doctors
may also prescribe either colchicine, which blocks the inflammation caused by uric
acid crystals, or low-dose nonsteroidal anti-inflammatory drugs (NSAIDs). After uric acid levels have been normal for 6 to 12 months and no further attacks
occur, colchicine or NSAIDs can be discontinued.
Liver and kidney function studies may be done after a few months of using xanthine oxidase inhibitors. These studies can be repeated as needed.
Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.
There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.
If you are pregnant, breast-feeding, or trying to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.
Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.
Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.
Colchicine and other drugs for gout. (2009). Medical Letter on Drugs and Therapeutics, 51(1326).
June 12, 2012
Anne C. Poinier, MD - Internal Medicine & Nancy Ann Shadick, MD, MPH - Internal Medicine, Rheumatology
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