Febuxostat

1 INDICATIONS AND USAGE Febuxostat tablets are xanthine oxidase (XO) inhibitor indicated for the chronic management of hyperuricemia in adult patients with gout who have an inadequate response to a maximally titrated dose of allopurinol, who are intolerant to allopurinol, or for whom treatment with allopurinol is not advisable. Limitations of Use : Febuxostat tablets are not recommended for the treatment of asymptomatic hyperuricemia. Febuxostat is a xanthine oxidase (XO) inhibitor indicated for the chronic management of hyperuricemia in adult patients with gout who have an inadequate response to a maximally titrated dose of allopurinol, who are intolerant to allopurinol, or for whom treatment with allopurinol is not advisable. (1) Limitations of Use : Febuxostat tablets are not recommended for the treatment of asymptomatic hyperuricemia. (1)

2 DOSAGE AND ADMINISTRATION · Recommended dosage is 40 mg or 80 mg once daily. The recommended starting dosage is 40 mg once daily. For patients who do not achieve a serum uric acid (sUA) less than 6 mg/dL after 2 weeks, the recommended dosage is 80 mg once daily. (2.1) · Patients with severe renal impairment: Limit the dosage to 40 mg once daily. (2.2, 8.6) · Flare prophylaxis is recommended upon initiation of febuxostat tablets. (2.4) · Can be administered without regard to food or antacid use. (2.1) 2.1 Recommended Dosage The recommended febuxostat tablets dosage is 40 mg or 80 mg once daily. The recommended starting dosage of febuxostat tablets is 40 mg once daily. For patients who do not achieve a serum uric acid (sUA) less than 6 mg/dL after two weeks, the recommended febuxostat tablets dosage is 80 mg once daily. Febuxostat tablets can be taken without regard to food or antacid use [see Clinical Pharmacology (12.3)]. Concurrent prophylactic treatment with a non-steroidal anti-inflammatory drug (NSAID) or colchicine is recommended [see Dosage and Administration (2.4) and Warnings and Precautions (5.2)]. 2.2 Dosage Recommendations in Patients with Renal Impairment and Hepatic Impairment The recommended dosage of febuxostat tablets is limited to 40 mg once daily in patients with severe renal impairment. No dose modification is necessary when administering febuxostat tablets in patients with mild or moderate renal impairment [see Use in Specific Populations (8.6) and Clinical Pharmacology (12.3)] . No dosage modification is necessary in patients with mild to moderate hepatic impairment [see Use in Specific Populations (8.7) and Clinical Pharmacology (12.3)] . 2.3 Serum Uric Acid Level Monitoring Testing for the target serum uric acid level of less than 6 mg/dL may be performed as early as two weeks after initiating febuxostat therapy. 2.4 Recommended Prophylaxis for Gout Flares Gout flares may occur after initiation of febuxostat due to changing serum uric acid levels resulting in mobilization of urate from tissue deposits. Flare prophylaxis with a non-steroidal anti-inflammatory drug (NSAID) or colchicine is recommended upon initiation of febuxostat. Prophylactic therapy may be beneficial for up to six months [see Clinical Studies (14.1)] . If a gout flare occurs during febuxostat treatment, febuxostat need not be discontinued. The gout flare should be managed concurrently, as appropriate for the individual patient [see Warnings and Precautions (5.2)] .

5 WARNINGS AND PRECAUTIONS · Gout Flares : An increase in gout flares is frequently observed after initiation of febuxostat. If a gout flare occurs during treatment, febuxostat need not be discontinued. Prophylactic therapy (i.e., non-steroidal anti-inflammatory drug or colchicine) upon initiation of treatment may be beneficial for up to six months.(2.4, 5.2) · Hepatic Effects: Cases of hepatic failure, some fatal, have been reported. If liver injury is detected, promptly interrupt febuxostat and treat cause, if possible, to resolution or stabilization. Permanently discontinue febuxostat if liver injury is confirmed, and no alternate etiology can be found. (5.3) · Serious Skin Reactions: Serious skin and hypersensitivity reactions, including Stevens-Johnson Syndrome, drug reaction with eosinophilia and systemic symptoms and toxic epidermal necrolysis have been reported in patients taking febuxostat. Discontinue febuxostat if serious skin reactions are suspected. (5.4) 5.1 Cardiovascular Death In a cardiovascular (CV) outcome study, gout patients with established CV disease treated with febuxostat tablets had a higher rate of CV death compared to those treated with allopurinol. Sudden cardiac death was the most common cause of adjudicated CV deaths, 2.7% in the febuxostat tablets group (83 of 3,098) as compared to 1.8% in the allopurinol group (56 of 3,092). Febuxostat tablets were similar to allopurinol for nonfatal myocardial infarction (MI), nonfatal stroke and unstable angina with urgent coronary revascularization [see Clinical Studies (14.2)] . Because of the increased risk of CV death, febuxostat tablets should only be used in patients who have an inadequate response to a maximally titrated dose of allopurinol, who are intolerant to allopurinol, or for whom treatment with allopurinol is not advisable [see Indications and Usage(1)] . Consider the risks and benefits of febuxostat tablets when deciding to prescribe or continue patients on febuxostat tablets. Consider use of prophylactic low-dose aspirin therapy in patients with a history of CV disease. Monitor patients for the development of CV events. Inform patients about the symptoms of serious CV events and the steps to take if they occur. 5.2 Gout Flares After initiation of febuxostat, an increase in gout flares is frequently observed. This increase is due to reduction in serum uric acid levels, resulting in mobilization of urate from tissue deposits. In order to prevent gout flares when febuxostat is initiated, concurrent prophylactic treatment with an NSAID or colchicine is recommended [see Dosage and Administration (2.4)]. 5.3 Hepatic Effects Cases of fatal and nonfatal hepatic failure in patients taking febuxostat have been reported. During randomized controlled studies, transaminase elevations greater than three times the upper limit of normal (ULN) were observed (AST: 2%, 2%, and ALT: 3%, 2% in febuxostat and allopurinol-treated patients, respectively). No dose-effect relationship for these transaminase elevations was noted [see Clinical Pharmacology (12.3)] . Obtain a liver test panel (serum alanine aminotransferase [ALT], aspartate aminotransferase [AST], alkaline phosphatase, and total bilirubin) as a baseline before initiating febuxostat. Measure liver tests promptly in patients who report symptoms that may indicate liver injury, including fatigue, anorexia, right upper abdominal discomfort, dark urine or jaundice. In this clinical context, if the patient presents abnormal liver tests (ALT or AST greater than three times the upper limit of the reference range), interrupt febuxostat treatment while investigating the probable cause. Permanently discontinue febuxostat if liver injury is confirmed, and no alternate etiology can be found. Permanently discontinue febuxostat in patients who have serum ALT or AST greater than three times the reference range with serum total bilirubin greater than two times the reference range without alternative etiologies because the…

4 CONTRAINDICATIONS Febuxostat tablets are contraindicated in patients being treated with azathioprine or mercaptopurine [see Drug Interactions (7)] . Febuxostat tablets are contraindicated in patients being treated with azathioprine or mercaptopurine. (4)

7 DRUG INTERACTIONS Concomitant administration of febuxostat with XO substrate drugs, azathioprine or mercaptopurine could increase plasma concentrations of these drugs resulting in severe toxicity. (7) 7.1 Xanthine Oxidase Substrate Drugs Febuxostat is an XO inhibitor. Based on a drug interaction study in healthy patients, febuxostat altered the metabolism of theophylline (a substrate of XO) in humans [see Clinical Pharmacology (12.3)]. Therefore, use with caution when coadministering febuxostat with theophylline. A drug interaction study of febuxostat and azathioprine, also metabolized by XO, showed an increase in exposure of 6-mercaptopurine which may lead to toxicity [see Clinical Pharmacology (12.3)] . Drug interaction studies of febuxostat with other drugs that are metabolized by XO (e.g., mercaptopurine) have not been conducted. Febuxostat is contraindicated in patients being treated with azathioprine or mercaptopurine [see Contraindications (4)]. 7.2 Cytotoxic Chemotherapy Drugs Drug interaction studies of febuxostat with cytotoxic chemotherapy have not been conducted. No data are available regarding the safety of febuxostat during cytotoxic chemotherapy. 7.3 In Vivo Drug Interaction Studies Based on drug interaction studies in healthy patients, febuxostat does not have clinically significant interactions with colchicine, naproxen, indomethacin, hydrochlorothiazide, warfarin or desipramine [see Clinical Pharmacology (12.3)]. Therefore, febuxostat may be used concomitantly with these medications.

8.1 Pregnancy Risk Summary Limited available data with febuxostat use in pregnant women are insufficient to inform a drug associated risk of adverse developmental outcomes. No adverse developmental effects were observed in embryo-fetal development studies with oral administration of febuxostat to pregnant rats and rabbits during organogenesis at doses that produced maternal exposures up to 40 and 51 times, respectively, the exposure at the maximum recommended human dose (MRHD). No adverse developmental effects were observed in a pre-and postnatal development study with administration of febuxostat to pregnant rats from organogenesis through lactation at an exposure approximately 11 times the MRHD (see Data) . The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the US 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 Animal Data In an embryo-fetal development study in pregnant rats dosed during the period of organogenesis from gestation Days 7 to 17, febuxostat was not teratogenic and did not affect fetal development or survival at exposures up to approximately 40 times the MRHD (on an AUC basis at maternal oral doses up to 48 mg/kg/day). In an embryo-fetal development study in pregnant rabbits dosed during the period of organogenesis from gestation Days 6 to 18, febuxostat was not teratogenic and did not affect fetal development at exposures up to approximately 51 times the MRHD (on an AUC basis at maternal oral doses up to 48 mg/kg/day). In a pre-and postnatal development study in pregnant female rats dosed orally from gestation Day 7 through lactation Day 20, febuxostat had no effects on delivery or growth and development of offspring at a dose approximately 11 times the MRHD (on an AUC basis at a maternal oral dose of 12 mg/kg/day). However, increased neonatal mortality and a reduction in neonatal body weight gain were observed in the presence of maternal toxicity at a dose approximately 40 times the MRHD (on an AUC basis at a maternal oral dose of 48 mg/kg/day). Febuxostat crossed the placental barrier following oral administration to pregnant rats and was detected in fetal tissues.

6 ADVERSE REACTIONS The following serious adverse reactions are described elsewhere in the prescribing information: Cardiovascular Death [see Warnings and Precautions (5.1)] Hepatic Effects [see Warnings and Precautions (5.3)] Serious Skin Reactions [see Warnings and Precautions (5.4)] Adverse reactions in 1% of patients treated with febuxostat are liver function abnormalities, nausea, arthralgia, and rash. (6.1) To report SUSPECTED ADVERSE REACTIONS, contact NorthStar RxLLC at 1-800-206-7821 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. In Phase 2 and 3 clinical studies, a total of 2757 patients with hyperuricemia and gout were treated with febuxostat 40 mg or 80 mg daily. For febuxostat 40 mg, 559 patients were treated for ≥6 months. For febuxostat 80 mg, 1377 patients were treated for ≥6 months, 674 patients were treated for ≥1 year and 515 patients were treated for ≥2 years. In the CARES study, a total of 3098 patients were treated with febuxostat 40 mg or 80 mg daily; of these, 2155 patients were treated for ≥1 year and 1539 were treated for ≥2 years [see Clinical Studies (14.2)] . Most Common Adverse Reactions In three randomized, controlled clinical studies (Studies 1, 2 and 3), which were 6 to 12 months in duration, the following adverse reactions were reported by the treating physician as related to study drug. Table 1 summarizes adverse reactions reported at a rate of at least 1% in febuxostat treatment groups and at least 0.5% greater than placebo. Table 1: Adverse Reactions Occurring in ≥1% of Patients Treated with Febuxostat and at Least 0.5% Greater than in Patients Receiving Placebo in Controlled Studies Adverse Reactions Placebo Febuxostat allopurinol Of the patients who received allopurinol, 10 received 100 mg, 145 received 200 mg, and 1122 received 300 mg, based on level of renal impairment. (N=134) 40 mg daily (N=757) 80 mg daily (N=1279) (N=1277) Liver Function Abnormalities 0.7% 6.6% 4.6% 4.2% Nausea 0.7% 1.1% 1.3% 0.8% Arthralgia 0% 1.1% 0.7% 0.7% Rash 0.7% 0.5% 1.6% 1.6% The most common adverse reaction leading to discontinuation from therapy was liver function abnormalities in 1.8% of febuxostat 40 mg, 1.2% of febuxostat 80 mg, and in 0.9% of patients treated with allopurinol. In addition to the adverse reactions presented in Table 1, dizziness was reported in more than 1% of patients treated with febuxostat although not at a rate more than 0.5% greater than placebo. In the CARES study, liver function abnormalities and diarrhea were reported in more than 1% of patients treated with febuxostat, although not at a rate more than 0.5% greater than allopurinol. Less Common Adverse Reactions In clinical studies the following adverse reactions occurred in less than 1% of patients and in more than one subject treated with doses ranging from 40 mg to 240 mg of febuxostat. This list also includes adverse reactions (less than 1% of patients) associated with organ systems from Warnings and Precautions. Blood and Lymphatic System Disorders : anemia, idiopathic thrombocytopenic purpura, leukocytosis/leukopenia, neutropenia, pancytopenia, splenomegaly, thrombocytopenia. Cardiac Disorders : angina pectoris, atrial fibrillation/flutter, cardiac murmur, ECG abnormal, palpitations, sinus bradycardia, tachycardia. Ear and Labyrinth Disorders : deafness, tinnitus, vertigo. Eye Disorders : vision blurred. Gastrointestinal Disorders : abdominal distention, abdominal pain, constipation, dry mouth, dyspepsia, flatulence, frequent stools, gastritis, gastroesophageal reflux disease, gastrointestinal discomfort, gingival pain, hematemesis, hyperchlorhydria, hematochezia, mouth ulceration, pancreatitis, peptic ulcer, vomiting. General Dis…