What is febuxostat?
Febuxostat (Adenuric™) is used in the long-term treatment and prevention of gout. Taken regularly, it can stop attacks of gout and help prevent damage to the joints.
The body naturally produces a substance called urate, which is normally dissolved in the blood until it's passed out of the body in the urine. When too much urate is produced, or if the body can't get rid of it properly, the blood can't dissolve all the urate and solid crystals can form in and around joints, causing inflammation and pain.
Febuxostat blocks an enzyme called xanthine oxidase which is involved in producing urate. By reducing the amount of urate produced febuxostat helps to keep the level low enough to allow the crystals to dissolve and prevent attacks of gout. You may already have tried another drug called allopurinol which works in a similar way.
Usually, you'll be prescribed febuxostat for gout if blood tests show your urate level is high and one or more of the following applies:
- you're having repeated attacks of gout
- your joints or kidneys have been damaged by attacks of gout
- you have deposits of urate crystals affecting your skin (gouty tophi).
Are there any reasons I won't be prescribed febuxostat?
Febuxostat is normally used only if allopurinol is unsuitable for you either because you have another condition or because you've had side-effects from allopurinol.
Febuxostat may not be suitable for you if you've had or have:
- a heart attack or certain types of heart disease
- severe kidney disease
- moderate or severe liver disease
- thyroid problems.
Your doctor will arrange for you to have a blood test before you start febuxostat to check your urate levels, kidney and liver.
Febuxostat contains lactose so you should tell your doctor if you're lactose intolerant.
How is it taken?
Your doctor may advise you not to start febuxostat until after an acute attack of gout has completely settled. If this isn't possible then febuxostat may be started while the gout is in a mild phase.
Febuxostat is taken as tablets once daily with or without food. The tablet should be swallowed with water.
Your doctor will advise you about the correct dose. Usually you’ll start with 80 mg daily, but your doctor will take regular blood tests and may increase the dose to 120 mg daily if your blood urate level doesn’t come down far enough for the crystals to dissolve.
Once your urate level is low and steady, you should have a blood test every three months to check for side-effects and every six months to check your urate level.
How long does it take to work?
Febuxostat lowers urate levels within a few weeks. However, urate crystals take much longer to dissolve. Until all of the crystals have dissolved, you may still get acute flares of gout. Acute attacks will normally stop within a year of treatment as long as your blood urate level has lowered.
Febuxostat isn't a treatment for acute attacks of gout and is generally needed for life. It's important to keep taking it (unless you have severe side-effects):
- even if it doesn't seem to be working at first
- even if you have more attacks of gout when you first start febuxostat
- even when you stop having attacks of gout – otherwise urate levels may start to build up again and your symptoms may come back.
Side-effects and risks
The most common side-effects are:
- skin rashes
- nausea (feeling sick)
- taste disturbance
- abnormal liver test results
- palpitations (irregular heart beat)
- reduced sex drive.
If you develop a rash when you start febuxostat, particularly within the first month, you should stop the medication immediately and discuss this with your GP. You should also tell your doctor if you develop any other new symptoms that concern you.
Sometimes when you start febuxostat it can trigger an acute attack of gout as the crystals begin to dissolve. This is more likely if your blood urate levels are very high and you've had gout for a long time, and it doesn't mean that the drug isn't working. You'll usually be given a medicine to take in addition to your febuxostat, which will reduce the risk of a flare of gout. This will be a small dose of either a non-steroidal anti-inflammatory drug (NSAID), colchicine or steroids.
If you do have an acute attack of gout while on febuxostat, don't stop taking it. Treat the attack as you would normally.
If you're unable to continue taking febuxostat, your doctor may suggest a drug such as benzbromarone or sulfinpyrazone, which reduce urate levels by increasing the amount of urate passed in the urine.
Effects on other treatments
You'll probably need a non-steroidal anti-inflammatory drug (NSAID), colchicine or steroids to deal with attacks of gout – especially in the early stages of febuxostat treatment. However, some drugs may interact with febuxostat, so you should discuss any new medication with your doctor before starting it, and you should always tell anyone else treating you that you're taking febuxostat.
The following drugs interact with febuxostat and generally should not be used alongside febuxostat:
- the immunosuppressant drugs azathioprine (used to treat immune diseases) and mercaptopurine (used to treat cancer and immune diseases)
- theophylline (used to treat asthma).
You can have vaccinations while on febuxostat.
Alcohol does not interact significantly with febuxostat, but it does increase the level of urate in the blood.
As part of the general treatment of gout, try to keep within the recommended limits for alcohol (14 units per week for adults). It's advisable to have alcohol-free days – but without saving up units to drink in one go.
Fertility, pregnancy and breastfeeding
It's rare for women to get gout before the menopause, but febuxostat is unlikely to affect fertility in either men or women.
However, we don't yet know what effect febuxostat might have on an unborn baby, so you shouldn't take it if you're pregnant. If you're planning a family or become pregnant while taking febuxostat you should discuss this with your doctor.
We don't know if febuxostat is passed into the breast milk. Therefore you shouldn't breastfeed if you're taking febuxostat.