Allopurinol

Description

11 DESCRIPTION Allopurinol, USP is a xanthine oxidase inhibitor. It has the following structural formula: Allopurinol, USP is known chemically as 1, 5-dihydro-4 H -pyrazolo [3, 4- d ]pyrimidin-4-one and it has a molecular weight of 136.1 g/mol. Soluble in solutions of potassium and sodium hydroxides, very slightly soluble in water and in alcohol; practically insoluble in chloroform and in ether. It is a xanthine oxidase inhibitor which is administered orally. Each scored white round-shaped tablet contains 100 mg allopurinol and the inactive ingredients colloidal silicon dioxide, lactose monohydrate, magnesium stearate, microcrystalline cellulose, sodium starch glycolate. Each scored orange round-shaped tablet contains 300 mg allopurinol and the inactive ingredients colloidal silicon dioxide, FD&C Yellow No. 6 Lake, lactose monohydrate, magnesium stearate, microcrystalline cellulose, sodium starch glycolate.

What Is Allopurinol Used For?

1 INDICATIONS AND USAGE Allopurinol tablets are indicated for: The management of adults with signs and symptoms of primary or secondary gout (acute attacks, tophi, joint destruction, uric acid lithiasis, and/or nephropathy) The management of adult and pediatric patients with leukemia, lymphoma and solid tumor malignancies who are receiving cancer therapy which causes elevations of serum and urinary uric acid levels The management of adult 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, despite lifestyle changes (such as reduction of dietary sodium, non-dairy animal protein, oxylate rich foods, refined sugars and increases in oral fluids and fruits and vegetables) Limitations of Use Allopurinol tablets are not recommended for the treatment of asymptomatic hyperuricemia. Allopurinol tablets are a xanthine oxidase inhibitor indicated for the management of: Adult patients with signs and symptoms of primary or secondary gout (acute attacks, tophi, joint destruction, uric acid lithiasis, and/or nephropathy) ( 1 ) Adult and pediatric patients with leukemia, lymphoma and solid tumor malignancies who are receiving cancer therapy which causes elevations of serum and urinary uric acid levels ( 1 ) Adult 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, despite lifestyle changes ( 1 ) Limitations of Use Allopurinol tablets are not recommended for the treatment of asymptomatic hyperuricemia. ( 1 )

Dosage and Administration

2 DOSAGE AND ADMINISTRATION Gout : Prior to initiating treatment assess serum uric acid level, complete blood count, chemistry panel, liver and kidney function tests. Prophylactic treatment for gout flares is recommended. ( 2.1 , 2.2 ) Patients with normal kidney function: Initial dosage is 100 mg orally daily. Increase by 100 mg weekly increments until serum uric acid of 6 mg/dl or less is reached (maximum 800 mg daily). ( 2.3 ) Patients with impaired kidney function: The initial dosage is 50 mg orally daily. Follow recommendations for titration in patients with renal impairment until target serum uric acid level is reached. ( 2.6 ) See complete information in the Full Prescribing Information (FPI). Hyperuricemia Associated with Cancer Therapy : The recommended dosage is: Adults: 300 mg to 800 mg orally daily. Pediatric patients: 100 mg/m 2 orally every 8 hours to 12 hours (10 mg/kg/day, maximum 800 mg/day) See complete information in the FPI. ( 2.4 , 2.6 ) Recurrent Calcium Oxalate Calculi : The recommended initial dosage in patients with normal kidney function is 200 mg to 300 mg orally daily. ( 2.5 ) Dosage in Patients with Renal Impairment: See FPI for dosage modifications in patients with renal impairment. ( 2.6 ) 2.1 Recommended Testing Prior to Treatment Initiation Prior to initiating treatment with allopurinol tablets in patients with gout, assess the following baseline tests: serum uric acid level, complete blood count, chemistry panel, liver function tests (serum alanine aminotransferase [ALT], aspartate aminotransferase [AST], alkaline phosphatase, and total bilirubin), kidney function tests (serum creatinine and eGFR). 2.2 Recommended Prophylaxis for Gout Flares Gout flares may occur after initiation of allopurinol tablets due to changing serum uric acid levels resulting in mobilization of urate from tissue deposits. Flare prophylaxis with colchicine or an anti- inflammatory agent according to practice guidelines is recommended upon initiation of allopurinol tablets. While adjusting the dosage of allopurinol tablets in patients who are being treated with colchicine and/or anti-inflammatory agents, continue flare prophylaxis drugs until serum uric acid has been normalized and the patient has been free of gout flares for several months. If a gout flare occurs during allopurinol tablets treatment, allopurinol tablets need not be discontinued. Manage the gout flare concurrently, as appropriate for the individual patient [see Warnings and Precautions ( 5.2 )]. 2.3 Recommended Dosage for Gout The initial recommended dosage for the management of gout is 100 mg orally daily, with weekly increments of 100 mg, until a serum uric acid level of 6 mg/dL or less is reached. Initiating treatment with lower dosages of allopurinol tablets and titrating slowly, decreases the risk of gout flares and drug induced serious adverse reactions. In patients with renal impairment the initial dosage is 50 mg orally daily with lower dose increases until serum...

Side Effects (Adverse Reactions)

6 ADVERSE REACTIONS The following clinically significant adverse reactions are described elsewhere in the labeling: Skin Rash and Hypersensitivity [see Warnings and Precautions ( 5.1 )] Nephrotoxicity [see Warnings and Precautions ( 5.3 )] Hepatoxicity [see Warnings and Precautions ( 5.4 )] Myelosuppression [see Warnings and Precautions ( 5.5 )] Potential Effect on Driving and Use of Machinery [see Warnings and Precautions ( 5.6 )] The following adverse reactions associated with the use of allopurinol tablets were identified in literature, unpublished clinical trials or postmarketing reports. Because some of these reactions were reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. The most frequent adverse reaction to allopurinol tablets is skin rash. Most Common Adverse Reactions (≥ 1%) Gastrointestinal : Diarrhea, nausea, alkaline phosphatase increase, AST/ALT increase. Metabolic and Nutritional : Acute attacks of gout. Skin and Appendages : Rash, maculopapular rash. Less Common Adverse Reactions (< 1%) Body As a Whole : Ecchymosis, fever, headache, malaise. Cardiovascular : Necrotizing angiitis, vasculitis, pericarditis, peripheral vascular disease, thrombophlebitis, bradycardia, vasodilation. Gastrointestinal : Hepatic necrosis, granulomatous hepatitis, hepatomegaly, hyperbilirubinemia, cholestatic jaundice, vomiting, intermittent abdominal pain, gastritis, dyspepsia, hemorrhagic pancreatitis, gastrointestinal bleeding, stomatitis, salivary gland swelling, hyperlipidemia, tongue edema, anorexia. Hemic and Lymphatic: Thrombocytopenia, eosinophilia, leukocytosis, leukopenia, aplastic anemia, agranulocytosis, eosinophilic fibrohistiocytic lesion of bone marrow, pancytopenia, prothrombin decrease, anemia, hemolytic anemia, reticulocytosis, lymphadenopathy, lymphocytosis. Musculoskeletal: Myopathy, arthralgias, myalgia. Nervous: Peripheral neuropathy, neuritis, paresthesia, somnolence, optic neuritis, confusion, dizziness, vertigo, foot drop, decrease in libido, depression, amnesia, tinnitus, asthenia, insomnia. Respiratory: Epistaxis, bronchospasm, asthma, pharyngitis, rhinitis. Skin and Appendages : Erythema multiforme exudativum (Stevens-Johnson syndrome), toxic epidermal necrolysis (Lyell's syndrome), hypersensitivity vasculitis, purpura, vesicular bullous dermatitis, exfoliative dermatitis, eczematoid dermatitis, pruritus, urticaria, alopecia, onycholysis, lichen planus, furunculosis, facial edema, sweating, skin edema. Special Senses : Taste loss/perversion, cataracts, macular retinitis, iritis, conjunctivitis, amblyopia. Urogenital: Renal failure, uremia, nephritis, impotence, primary hematuria, albuminuria. Endocrine: Infertility (male), hypercalcemia, gynecomastia (male). Most common adverse reactions (incidence > 1%) are nausea, diarrhea, and increase in liver function tests. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Par Pharmaceutical at 1-800-828-9393 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Drug Interactions

7 DRUG INTERACTIONS The following drugs may increase the risk of serious skin reactions: bendamustine, thiazide diuretics, ampicillin and amoxicillin. ( 7.1 ) Capecitabine: Avoid concomitant use. ( 7.2 ) Mercaptopurine or Azathioprine: Reduce mercaptopurine or azathioprine dose as recommended in the respective prescribing information. ( 7.2 ) Pegloticase: Discontinue and refrain from initiating treatment with allopurinol tablets. ( 7.2 ) See FPI for complete list of significant drug interactions. ( 7.2 ) 7.1 Drugs Known to Affect the Occurrence of Skin Rash and Hypersensitivity Concomitant use of the following drugs may increase the risk of skin rash, which may be severe: bendamustine, thiazide diuretics, ampicillin and amoxicillin. Renal impairment may further increase risk with concomitant use of thiazide diuretics [see Warnings and Precautions ( 5.1 , 5.2 ) and Clinical Pharmacology ( 12.2 )] . Monitor kidney function and reduce the dose of allopurinol tablets in patients with concomitant thiazide diuretic use and impaired renal function [see Dosage and Administration ( 2.6 ), Warnings and Precautions ( 5.1 )]. Discontinue allopurinol tablets at the first appearance of skin rash or other signs which may indicate a hypersensitivity reaction when use concomitantly with these drugs [see Warnings and Precautions ( 5.1 )] . 7.2 Drugs Known to Have Clinically Important Drug Interactions with Allopurinol Tablets Table 3: Interventions for Clinically Important Drug Interactions with Allopurinol Tablets Capecitabine Clinical Impact Concomitant use with allopurinol may decrease concentration of capecitabine’s active metabolites, which may decrease capecitabine efficacy. Intervention Avoid the use of allopurinol tablets during treatment with capecitabine. Chlorpropamide Clinical Impact Allopurinol tablets prolong the half-life of chlorpropamide as both compete for renal tubular excretion. In patients with renal insufficiency, the risk of hypoglycemia may be increased due to this mechanism. Intervention Monitor patients with renal insufficiency for hypoglycemia when administering chlorpropamide and allopurinol tablets concomitantly. Cyclosporine Clinical Impact Concomitant use of allopurinol increases cyclosporine concentrations, which may increase the risk of adverse reactions. Intervention Increase frequency of monitoring cyclosporine concentrations as reflected in its prescribing information and modify the dosage of cyclosporine as appropriate when used concomitantly with allopurinol tablets. Cyclophosphamide and Other Cytotoxic Agents Clinical Impact Concomitant use of allopurinol with cyclophosphamide and other cytotoxic agents (doxorubicin, bleomycin, procarbazine, mechloroethamine) increases bone marrow suppression among patients with neoplastic disease, except leukemia. Intervention Blood count monitoring and regular physician follow-up are recommended. Dicumarol Clinical Impact Allopurinol tablets prolong the half-life of the anticoagulant,...

Contraindications

4 CONTRAINDICATIONS Allopurinol tablets are contraindicated in patients with a history of hypersensitivity reaction to allopurinol or to any of the ingredients of allopurinol tablets. Known hypersensitivity to allopurinol or to any of the ingredients of allopurinol tablets.

Pregnancy and Breastfeeding

8.1 Pregnancy Risk Summary Based on findings in animals, allopurinol tablets may cause fetal harm when administered to a pregnant woman. Adverse developmental outcomes have been described in exposed animals (see Data). Allopurinol and its metabolite oxypurinol have been shown to cross the placenta following administration of maternal allopurinol. Available limited published data on allopurinol use in pregnant women do not demonstrate a clear pattern or increase in frequency of adverse developmental outcomes. Among approximately 50 pregnancies described in published literature, 2 infants with major congenital malformations have been reported with following maternal allopurinol exposure. Advise pregnant women of the potential risk to a fetus. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. The background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Data Human Data Experience with allopurinol tablets during human pregnancy has been limited partly because women of reproductive age rarely require treatment with allopurinol tablets. A case report published in 2011 described the outcome of a full-term pregnancy in a 35-year-old woman who had recurrent kidney stones since age 18 who took allopurinol throughout the pregnancy. The child had multiple complex birth defects and died at 8 days of life. A second report in 2013 provided data on 31 prospectively ascertained pregnancies involving mothers exposed to allopurinol for varying durations during the first trimester. The overall rate of major fetal malformations and spontaneous abortions was reported to be within the normal expected range; however, one child had severe malformations similar to those described in the cited earlier case report. Animal Data There was no...

8.3 Nursing Mothers

Overdosage

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

How Supplied

16 HOW SUPPLIED 300 mg Orange, round and biconvex tablets. The upper layer is bisected and debossed with “2084/V”. The lower layer is plain. They are supplied as follows: Bottles of 1000: 63629-2113-1 Store at 20°C to 25°C (USP Controlled Room Temperature) (68°F to 77°F) in a dry place. Dispense in a tight container as defined in the USP. Repackaged/Relabeled by: Bryant Ranch Prepack, Inc. Burbank, CA 91504