Allopurinol general information

What is Allopurinol used for?

Allopurinol tablets 100mg are used to treat several conditions that are caused by a build-up of uric acid in the blood (hyperuricaemia) and the deposition of uric acid crystals throughout the body.  Particularly for the management of primary gout or secondary hyperuricaemia associated with chronic gout.  Allopurinol tablets 100mg are not used to treat an acute attack of gout as it has no analgesic, antiinflammatory or uricosuric activity (increases the excretion of uric acid in the urine) and may prolong the attack. Conditions that Allopurinol tablets 100mg are used for include idiopathic gout (without known cause) or gouty arthritis, in which uric acid crystals are deposited in joints causing pain and swelling; kidney stones or uric acid nephrolithiasis (uric acid crystals in the kidney) and skin tophi (uric acid crystals beneath the skin).  Allopurinol tablets 100mg are also used for clinical conditions where there is a risk of uric acid build up and deposition, particularly as a result of chemotherapy or radiation therapy for cancer, which can lead to acute uric acid nephropathy, due to high levels of uric acid in the urine (hyperuricosuria) causing loss of kidney function.  Overproduction of uric acid may also be caused by certain tumours with high cell turnover rates like leukaemia or lymphoma.  Other rare conditions due to high levels of uric acid in the blood are caused by overproduction of certain enzymes such as hypoxanthine-guanine phosphoribosyltransferase, which causes Lesch-Nyhan syndrome and adenine phosphoribosyltransferase which can cause kidney stones.  Kidney stones can also be caused by deposition of a mixture of crystals, such those including calcium oxalate along with high levels of uric acid in the urine and Allopurinol tablets 100mg can be used to treat these kidney stones when other treatments such as increased fluid intake and dietary changes have failed.  

How does Allopurinol work?

Allopurinol tablets 100mg contain allopurinol, an inhibitor of the enzyme xanthine oxidase, which plays an important role in the production of uric acid, the end product of purine metabolism.  Purines are obtained from the diet mainly from meat, meat products and seafood, but are also synthesised in the body.  Xanthine oxidase catalyses the conversion of hypoxanthine to xanthine and xanthine to uric acid, the final oxidation product of purine metabolism excreted in the urine.  Inhibition of xanthine oxidase by allopurinol in Allopurinol tablets 100mg reduces the levels of uric acid in the blood and this helps prevent deposition of uric acid crystals in the joints.  Levels of hypoxanthine and xanthine increase as they are not metabolised to uric acid and this induces a negative feedback mechanism on the synthesis of purines, which further reduces the amount of uric acid in the blood.  The inhibitory action of allopurinol in Allopurinol tablets 100mg on the purine metabolic cycle (synthesis and breakdown) prevents the build up of uric acid and thereby reduces the amount of uric acid crystals that are deposited in the joints, reducing the frequency of attacks of gout and acute gouty arthritis to improve joint mobility.  This action of allopurinol in Allopurinol tablets 100mg also allows skin tophi to heal and resolve and prevents the formation of kidney stones, which thereby prevents kidney damage. 

What does Allopurinol contain?

Allopurinol tablets 100mg contain the active ingredient allopurinol, an inhibitor of the enzyme xanthine oxidase that is used to treat conditions caused by deposition of uric acid crystals including gout, gouty arthritis and kidney stones.  They also contain lactose monohydrate, maize starch, povidone, magnesium stearate.

Treating gout with Allopurinol

Allopurinol tablets 100mg contain allopurinol that helps reduce levels of uric acid in the blood (hyperuricaemia), which can lead to deposition of uric acid crystals in joints.  This is the cause of the condition known as gout resulting in painful swollen joints with loss of joint mobility.  Allopurinol in Allopurinol tablets 100mg inhibits the enzyme xanthine oxidase, which plays an important role in the production of uric acid, the end product of purine metabolism.  Purines are obtained from the diet mainly from meat, meat products and seafood, but are also synthesised in the body.  Xanthine oxidase catalyses the conversion of hypoxanthine to xanthine and xanthine to uric acid, the final oxidation product of purine metabolism, excreted in the urine.  Inhibition of xanthine oxidase by allopurinol in Allopurinol tablets 100mg reduces the levels of uric acid in the blood by preventing metabolism of purines into uric acid as well as preventing new synthesis of purines.  Both mechanisms reduce the formation and accumulation of uric acid in the blood, which helps prevent deposition of uric acid crystals in the joints.  Allopurinol tablets 100mg are used to manage primary gout or secondary hyperuricaemia associated with chronic gout, to relieve the pain, swelling and loss of mobility in the affected joint, but are not used to treat an acute attack of gout.

Allopurinol for kidney stones

Allopurinol tablets 100mg contain the active ingredient allopurinol that helps reduce levels of uric acid in the blood (hyperuricaemia) that can lead to deposition of uric acid crystals in the kidneys causing kidney stones or uric acid nephrolithiasis.  Allopurinol in Allopurinol tablets 100mg inhibits the enzyme xanthine oxidase, which plays an important role in the production of uric acid, the end product of purines metabolism.  Purines are obtained from the diet mainly from meat, meat products and seafood, but are also synthesised in the body.  Xanthine oxidase catalyses the conversion of hypoxanthine to xanthine and xanthine to uric acid, the final oxidation product of purine metabolism, excreted in the urine.  Inhibition of xanthine oxidase by allopurinol in Allopurinol tablets 100mg reduces the levels of uric acid in the blood by preventing metabolism of purines into uric acid as well as preventing new synthesis of purines.  Both mechanisms reduce the formation and accumulation of uric acid in the blood, which helps prevent deposition of uric acid crystals in the kidneys.  Some kidney stones are caused by deposition of a mixture of crystals, such those including calcium oxalate along with high levels of uric acid in the urine and Allopurinol tablets 100mg can be used to treat these kidney stones when other treatments such as increased fluid intake and dietary changes have failed. 

What are the side effects of Allopurinol?

The most commonly reported side effects when taking Allopurinol tablets 100mg include skin rash, itching, generalised hypersensitivity reaction, gastrointestinal upset mainly nausea and vomiting.  Less common but more serious reactions include liver dysfunction, tingling or numbness of the hands or feet (paraesthesia).

When should Allopurinol not be used?

You should not use Allopurinol tablets 100mg if you:

• are allergic to allopurinol or any ingredients in Allopurinol
• are pregnant or are breastfeeding
• have kidney or liver disease
• are having an acute attack of gout
• have or an immediate relative has haemochromatosis, (too much iron in the body), and are also taking iron salts
• are taking medicines that interact with Allopurinolincluding the immunosuppressants cyclosporin and azathioprine, 6-mercaptopurine for cancer treatment, the antiviral vidarabine, aspirin and other salicylates, probenecid for gout, chlorpropamide for diabetes, the antibiotics ampicillin and amoxicillin, phenytoin for epilepsy, theophylline for asthma

What medications interact with Allopurinol?

Several medications interact with Allopurinol tablets 100mg and should either not be taken while you are taking Allopurinol or only after discussion and instruction from your doctor:

• Drugs that cause a serious reaction with Allopurinol: chlorpropamide for diabetes, the antibiotics ampicillin and amoxicillin
• Drugs that affect Allopurinol: aspirin and other salicylates, probenecid for gout
• Drugs that are affected by Allopurinol: the immunosuppressants cyclosporin and azathioprine, 6-mercaptopurine for cancer treatment, the antiviral vidarabine, phenytoin for epilepsy, theophylline for asthma

How should Allopurinol be taken?

You should take your Allopurinol tablets 100mg once daily with a glass of water and after a meal to reduce risk of gastrointestinal side effects.  The dose you take depends on your conditions, your age and your doctor’s recommendations.  You should continue to take your Allopurinol tablets 100mg daily until your condition improves or for as long as your doctor recommends.

How long should you take Allopurinol?

You should continue to take your Allopurinol tablets 100mg daily until your condition improves or for as long as your doctor recommends.

Missed dose of Allopurinol

If you miss a dose of Allopurinol take it as soon as you remember, unless it is time to take the next dose, then skip the missed dose.  Do not take a double dose.

How should Allopurinol be stored?

You should store your Allopurinol below 25°C in a cool dry place.