Allopurinol

What is Allopurinol?

• Allopurinol (Lopurin; Zyloprim) is a xanthine oxidase inhibitor used to decrease high blood uric acid levels.
• It is specifically used to prevent gout, prevent specific types of kidney stones and for the high uric acid levels that can occur with chemotherapy.

Allopurinol structure

Allopurinol 3d structure

What are the uses of this medicine?

Allopurinol (Lopurin; Zyloprim) is used for:

• the management of patients with signs and symptoms of primary or secondary gout (acute attacks, tophi, joint destruction, uric acid lithiasis, and/or nephropathy).
• the management of patients with leukemia, lymphoma and malignancies who are receiving cancer therapy which causes elevations of serum and urinary uric acid levels.
• the management of patients with recurrent calcium oxalate calculi whose daily uric acid excretion exceeds 800 mg/day in male patients and 750 mg/day in female patients.

How does this medicine work?

• Allopurinol (al' oh pure' i nol) is an analog of hypoxanthine and a potent inhibitor of the enzyme xanthine oxidase that is responsible for converting hypoxanthine to xanthine and xanthine to uric acid in the breakdown pathway of purines.
• Allopurinol lowers serum and tissue uric acid levels and has potent activity against gout, largely in preventing rather than treating acute attacks of gout.

Who Should Not Use this medicine ?

This medicine cannot be used in patients who:

• have developed a severe reaction to allopurinol.

What drug interactions can this medicine cause?

• Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.
• In patients receiving mercaptopurine or IMURAN (azathioprine), the concomitant administration of 300 to 600 mg of allopurinol per day will require a reduction in dose to approximately one third to one fourth of the usual dose of mercaptopurine or azathioprine.
• The reports that the concomitant use of allopurinol and thiazide diuretics may contribute to the enhancement of allopurinol toxicity.
• It has been reported that allopurinol prolongs the half-life of the anticoagulant, dicumarol.
• An increase in the frequency of skin rash has been reported among patients receiving ampicillin or amoxicillin concurrently with allopurinol compared to patients who are not receiving both drugs.
• The risk of hypoglycemia secondary to this mechanism may be increased if allopurinol and chlorpropamide are given concomitantly in the presence of renal insufficiency.
• Monitoring of cyclosporine levels and possible adjustment of cyclosporine dosage should be considered when these drugs are co-administered.

Is this medicine FDA approved?

• Allopurinol was approved for use in the United States in 1963 and is still widely used.
• Current indications include therapy and prevention of gout, uric acid nephropathy, and the hyperuricemia caused by malignancy and anticancer therapy.
• It is not recommended for treatment of asymptomatic hyperuricemia.

How should this medicine be used?

Recommended dosage:

• The average is 200 to 300 mg/day for patients with mild gout and 400 to 600 mg/day for those with moderately severe tophaceous gout.
• The appropriate dosage may be administered in divided doses or as a single equivalent dose with the 300 mg-tablet.
• Dosage requirements in excess of 300 mg should be administered in divided doses.
• The minimal effective dosage is 100 to 200 mg daily and the maximal recommended dosage is 800 mg daily.
• To reduce the possibility of flare-up of acute gouty attacks, it is recommended that the patient start with a low dose of allopurinol (100 mg daily) and increase at weekly intervals by 100 mg until a serum uric acid level of 6 mg/dL or less is attained but without exceeding the maximal recommended dosage.

Administration:

• Allopurinol comes as a tablet to take by mouth.
• It is usually taken once or twice a day, preferably after a meal.
• Your doctor will probably start you on a low dose of allopurinol and gradually increase your dose, not more than once a week.
• It may take several months or longer before you feel the full benefit of allopurinol.
• Allopurinol may increase the number of gout attacks during the first few months that you take it, although it will eventually prevent attacks.
• Your doctor may prescribe another medication such as colchicine to prevent gout attacks for the first few months you take allopurinol.
• Continue to take allopurinol even if you feel well. Do not stop taking allopurinol without talking to your doctor.

What are the dosage forms and brand names of this medicine?

This medicine is available in fallowing doasage form:

• As Tablets of 100 and 300 mg. Intravenous formulations are also available.

This medicine is available in fallowing brand namesː

• Lopurin; Zyloprim

What side effects can this medication cause?

The most common side effects of this medicine include:

• Diarrhea
• nausea
• alkaline phosphatase increase
• SGOT/SGPT increase
• Acute attacks of gout
• Rash
• maculopapular rash

What special precautions should I follow?

• An increase in acute attacks of gout has been reported during the early stages of administration of allopurinol, even when normal or subnormal serum uric acid levels have been attained.
• Renal failure in association with administration of allopurinol has been observed among patients with hyperuricemia secondary to neoplastic diseases. Patients with decreased renal function require lower doses of allopurinol than those with normal renal function.
• Bone marrow depression has been reported in patients receiving allopurinol, most of whom received concomitant drugs with the potential for causing this reaction.
• Allopurinol is a rare but well known cause of acute liver injury that has features of a hypersensitivity reaction and can be severe and even fatal. In patients with pre-existing liver disease, periodic liver function tests are recommended during the early stages of therapy.
• Due to the occasional occurrence of drowsiness, patients should be alerted to the need for due precaution when engaging in activities where alertness is mandatory.
• Discontinue allopurinol and to consult their physician immediately at the first sign of a skin rash, painful urination, blood in the urine, irritation of the eyes, or swelling of the lips or mouth.
• Allopurinol and oxipurinol have been found in the milk of a mother who was receiving allopurinol. Since the effect of allopurinol on the nursing infant is unknown, caution should be exercised when allopurinol is administered to a nursing woman.

What to do in case of emergency/overdose?

Symptoms of overdosage may include:

• Massive overdosing or acute poisoning by allopurinol has not been reported.

Management of overdosage:

• In the management of overdosage there is no specific antidote for allopurinol.
• Both allopurinol and oxipurinol are dialyzable; however, the usefulness of hemodialysis or peritoneal dialysis in the management of an overdose of allopurinol is unknown.

Can this medicine be used in pregnancy?

• There are, however, no adequate or well-controlled studies in pregnant women.
• Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.

Can this medicine be used in children?

• Allopurinol is rarely indicated for use in children with the exception of those with hyperuricemia secondary to malignancy.

What are the active and inactive ingredients in this medicine?

Active ingredient:

• ALLOPURINOL

Inactive ingredients:

• SILICON DIOXIDE
• LACTOSE MONOHYDRATE
• MAGNESIUM STEARATE
• CELLULOSE, MICROCRYSTALLINE
• SODIUM STARCH GLYCOLATE TYPE A POTATO

Who manufactures and distributes this medicine?

Dist. by:

• Par Pharmaceutical
• Chestnut Ridge, NY U.S.A.

What should I know about storage and disposal of this medication?

• Store at 20° to 25°C (68° to 77°F).

The following drugs are considered antigout medications:

• Allopurinol
• Benzbromarone
• Colchicine
• Febuxostat
• Lesinurad
• Pegloticase
• Probenecid
• Rasburicase

• Dailymed label info on Allopurinol
• FDA Allopurinol

Allopurinol Resources
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