Febuxostat Drug Information

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. Limitations of Use: Febuxostat tablets are not recommended for the treatment of asymptomatic hyperuricemia.

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. Concurrent prophylactic treatment with a non-steroidal anti-inflammatory drug (NSAID) or colchicine is recommended.

No dose modification is necessary when administering febuxostat tablets in patients with mild or moderate renal impairment. No dosage modification is necessary in patients with mild to moderate hepatic impairment.

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 tablets therapy.

Recommended Prophylaxis for Gout Flares

Gout flares may occur after initiation of febuxostat tablets 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 tablets. Prophylactic therapy may be beneficial for up to six months.

If a gout flare occurs during febuxostat tablets treatment, febuxostat tablets need not be discontinued. The gout flare should be managed concurrently, as appropriate for the individual patient.

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. For febuxostat 40 mg, 559 patients were treated for ≥6 months. 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 Disorders and Administration Site Conditions: asthenia, chest pain/discomfort, edema, fatigue, feeling abnormal, gait disturbance, influenza-like symptoms, mass, pain, thirst.

Hepatobiliary Disorders: cholelithiasis/cholecystitis, hepatic steatosis, hepatitis, hepatomegaly. Immune System Disorder: hypersensitivity. Infections and Infestations: herpes zoster.

Procedural Complications: contusion. Metabolism and Nutrition Disorders: anorexia, appetite decreased/increased, dehydration, diabetes mellitus, hypercholesterolemia, hyperglycemia, hyperlipidemia, hypertriglyceridemia, hypokalemia, weight decreased/increased. Musculoskeletal and Connective Tissue Disorders: arthritis, joint stiffness, joint swelling, muscle spasms/twitching/tightness/weakness, musculoskeletal pain/stiffness, myalgia.

Nervous System Disorders: altered taste, balance disorder, cerebrovascular accident, Guillain-Barre syndrome, headache, hemiparesis, hypoesthesia, hyposmia, lacunar infarction, lethargy, mental impairment, migraine, paresthesia, somnolence, transient ischemic attack, tremor. Psychiatric Disorders: agitation, anxiety, depression, insomnia, irritability, libido decreased, nervousness, panic attack, personality change. Renal and Urinary Disorders: hematuria, nephrolithiasis, pollakiuria, proteinuria, renal failure, renal insufficiency, urgency, incontinence.

Reproductive System and Breast Changes: breast pain, erectile dysfunction, gynecomastia. Respiratory, Thoracic and Mediastinal Disorders: bronchitis, cough, dyspnea, epistaxis, nasal dryness, paranasal sinus hypersecretion, pharyngeal edema, respiratory tract congestion, sneezing, throat irritation, upper respiratory tract infection. Skin and Subcutaneous Tissue Disorders: alopecia, angio-edema, dermatitis, dermographism, ecchymosis, eczema, hair color changes, hair growth abnormal, hyperhidrosis, peeling skin, petechiae, photosensitivity, pruritus, purpura, skin discoloration/altered pigmentation, skin lesion, skin odor abnormal, urticaria.

Vascular Disorders: flushing, hot flush, hypertension, hypotension. Laboratory Parameters: activated partial thromboplastin time prolonged, creatine increased, bicarbonate decreased, sodium increased, EEG abnormal, glucose increased, cholesterol increased, triglycerides increased, amylase increased, potassium increased, TSH increased, platelet count decreased, hematocrit decreased, hemoglobin decreased, MCV increased, RBC decreased, creatinine increased, blood urea increased, BUN/creatinine ratio increased, creatine phosphokinase (CPK) increased, alkaline phosphatase increased, LDH increased, PSA increased, urine output increased/decreased, lymphocyte count decreased, neutrophil count decreased, WBC increased/decreased, coagulation test abnormal, low density lipoprotein (LDL) increased, prothrombin time prolonged, urinary casts, urine positive for white blood cells and protein.

Postmarketing Experience

The following adverse reactions have been identified during post approval use of febuxostat. Because these reactions are 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. Blood and Lymphatic System Disorders: agranulocytosis, eosinophilia.

Hepatobiliary Disorders: hepatic failure (some fatal), jaundice, serious cases of abnormal liver function test results, liver disorder. Immune System Disorders: anaphylaxis, anaphylactic reaction. Musculoskeletal and Connective Tissue Disorders: rhabdomyolysis.

Psychiatric Disorders: psychotic behavior including aggressive thoughts. Renal and Urinary Disorders: tubulointerstitial nephritis. Skin and Subcutaneous Tissue Disorders: generalized rash, Stevens-Johnson syndrome, hypersensitivity skin reactions, erythema multiforme, drug reaction with eosinophilia and systemic symptoms, toxic epidermal necrolysis.

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. 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. 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.

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.

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. Therefore, febuxostat may be used concomitantly with these medications.

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 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 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.

Pediatric Use Safety and effectiveness of febuxostat in pediatric patients have not been established.

Febuxostat tablets are contraindicated in patients being treated with azathioprine or mercaptopurine.

Febuxostat was studied in healthy patients in doses up to 300 mg daily for seven days without evidence of dose-limiting toxicities. No overdose of febuxostat was reported in clinical studies. Patients should be managed by symptomatic and supportive care should there be an overdose.