Uloric is a xanthine oxidase (XO) inhibitor indicated for the chronic management of hyperuricemia in patients with gout.
Uloric is not recommended for the treatment of asymptomatic hyperuricemia.
Uloric Dosage and Administration
Recommended Dose
For treatment of hyperuricemia in patients with gout, Uloric is recommended at 40 mg or 80 mg once daily.
The recommended starting dose of Uloric is 40 mg once daily. For patients who do not achieve a serum uric acid (sUA) less than 6 mg per dL after 2 weeks with 40 mg, Uloric 80 mg is recommended.
Uloric can be taken without regard to food or antacid use [see Clinical Pharmacology (12.3)].
Special Populations
No dose adjustment is necessary when administering Uloric in patients with mild to moderate renal impairment [see Use in Specific Populations (8.6) and Clinical Pharmacology (12.3)]. The recommended starting dose of Uloric is 40 mg once daily. For patients who do not achieve a sUA less than 6 mg per dL after 2 weeks with 40 mg, Uloric 80 mg is recommended.
No dose adjustment is necessary in patients with mild to moderate hepatic impairment [see Use in Specific Populations (8.7) and Clinical Pharmacology (12.3)].
Uric Acid Level
Testing for the target serum uric acid level of less than 6 mg per dL may be performed as early as 2 weeks after initiating Uloric therapy.
Gout Flares
Gout flares may occur after initiation of Uloric 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 Uloric. Prophylactic therapy may be beneficial for up to six months [see Clinical Studies (14.1)].
If a gout flare occurs during Uloric treatment, Uloric need not be discontinued. The gout flare should be managed concurrently, as appropriate for the individual patient [see Warnings and Precautions (5.1)].
Dosage Forms and Strengths
- 40 mg tablets, light green to green, round shaped, debossed with "TAP" and "40"
- 80 mg tablets, light green to green, teardrop shaped, debossed with "TAP" and "80"
Contraindications
Uloric is contraindicated in patients being treated with azathioprine or mercaptopurine [see Drug Interactions (7)].
Warnings and Precautions
Gout Flare
After initiation of Uloric, 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 Uloric is initiated, concurrent prophylactic treatment with an NSAID or colchicine is recommended [see Dosage and Administration (2.4)].
Cardiovascular Events
In the randomized controlled studies, there was a higher rate of cardiovascular thromboembolic events (cardiovascular deaths, non-fatal myocardial infarctions, and non-fatal strokes) in patients treated with Uloric [0.74 per 100 P-Y (95% Confidence Interval (CI) 0.36-1.37)] than allopurinol [0.60 per 100 P-Y (95% CI 0.16-1.53)] [see Adverse Reactions (6.1)]. A causal relationship with Uloric has not been established. Monitor for signs and symptoms of myocardial infarction (MI) and stroke.
Liver Enzyme Elevations
During randomized controlled studies, transaminase elevations greater than 3 times the upper limit of normal (ULN) were observed (AST: 2%, 2%, and ALT: 3%, 2% in Uloric and allopurinol-treated patients, respectively). No dose-effect relationship for these transaminase elevations was noted. Laboratory assessment of liver function is recommended at, for example, 2 and 4 months following initiation of Uloric and periodically thereafter.
Adverse Reactions
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.
A total of 2757 subjects with hyperuricemia and gout were treated with Uloric 40 mg or 80 mg daily in clinical studies. For Uloric 40 mg, 559 patients were treated for ≥ 6 months. For Uloric 80 mg, 1377 subjects were treated for ≥ 6 months, 674 patients were treated for ≥ 1 year and 515 patients were treated for ≥ 2 years.
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 Uloric treatment groups and at least 0.5% greater than placebo.
| Table 1: Adverse Reactions Occurring in ≥ 1% of Uloric-Treated Patients and at Least 0.5% Greater than Seen in Patients Receiving Placebo in Controlled Studies |
|---|
| Adverse Reactions |
Placebo |
Uloric |
allopurinol |
|---|
| (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 Uloric 40 mg, 1.2% of Uloric 80 mg, and in 0.9% of allopurinol-treated subjects.
In addition to the adverse reactions presented in Table 1, dizziness was reported in more than 1% of Uloric-treated subjects although not at a rate more than 0.5% greater than placebo.
Less Common Adverse Reactions
In Phase 2 and 3 clinical studies the following adverse reactions occurred in less than 1% of subjects and in more than one subject treated with doses ranging from 40 mg to 240 mg of Uloric. This list also includes adverse reactions (less than 1% of subjects) 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, haematemesis, 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-Barré 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.
Cardiovascular Safety
Cardiovascular events and deaths were adjudicated to one of the pre-defined endpoints from the Anti-Platelet Trialists' Collaborations (APTC) (cardiovascular death, non-fatal myocardial infarction, and non-fatal stroke) in the randomized controlled and long-term extension studies. In the Phase 3 randomized controlled studies, the incidences of adjudicated APTC events per 100 patient-years of exposure were: Placebo 0 (95% CI 0.00-6.16), Uloric 40 mg 0 (95% CI 0.00-1.08), Uloric 80 mg 1.09 (95% CI 0.44-2.24), and allopurinol 0.60 (95% CI 0.16-1.53).
In the long-term extension studies, the incidences of adjudicated APTC events were: Uloric 80 mg 0.97 (95% CI 0.57-1.56), and allopurinol 0.58 (95% CI 0.02-3.24).
Overall, a higher rate of APTC events was observed in Uloric than in allopurinol-treated patients. A causal relationship with Uloric has not been established. Monitor for signs and symptoms of MI and stroke.
Postmarketing Experience
Adverse reactions have been identified during post approval use of Uloric. 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.
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.
Drug Interactions
Xanthine Oxidase Substrate Drugs
Uloric is an XO inhibitor. Based on a drug interaction study in healthy subjects, febuxostat altered the metabolism of theophylline (a substrate of XO) in humans [see Clinical Pharmacology (12.3)]. Therefore, use with caution when co-administering Uloric with theophylline.
Drug interaction studies of Uloric with other drugs that are metabolized by XO (e.g., mercaptopurine and azathioprine) have not been conducted. Inhibition of XO by Uloric may cause increased plasma concentrations of these drugs leading to toxicity [see Clinical Pharmacology (12.3)]. Uloric is contraindicated in patients being treated with azathioprine or mercaptopurine [see Contraindications (4)].
Cytotoxic Chemotherapy Drugs
Drug interaction studies of Uloric with cytotoxic chemotherapy have not been conducted. No data are available regarding the safety of Uloric during cytotoxic chemotherapy.
In Vivo Drug Interaction Studies
Based on drug interaction studies in healthy subjects, Uloric does not have clinically significant interactions with colchicine, naproxen, indomethacin, hydrochlorothiazide, warfarin or desipramine [see Clinical Pharmacology (12.3)]. Therefore, Uloric may be used concomitantly with these medications.
USE IN SPECIFIC POPULATIONS
Pregnancy
Pregnancy Category C: There are no adequate and well-controlled studies in pregnant women. Uloric should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Febuxostat was not teratogenic in rats and rabbits at oral doses up to 48 mg per kg (40 and 51 times the human plasma exposure at 80 mg per day for equal body surface area, respectively) during organogenesis. However, increased neonatal mortality and a reduction in the neonatal body weight gain were observed when pregnant rats were treated with oral doses up to 48 mg per kg (40 times the human plasma exposure at 80 mg per day) during organogenesis and through lactation period.
Nursing Mothers
Febuxostat is excreted in the milk of rats. It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when Uloric is administered to a nursing woman.
Pediatric Use
Safety and effectiveness in pediatric patients under 18 years of age have not been established.
Geriatric Use
No dose adjustment is necessary in elderly patients. Of the total number of subjects in clinical studies of Uloric, 16 percent were 65 and over, while 4 percent were 75 and over. Comparing subjects in different age groups, no clinically significant differences in safety or effectiveness were observed but greater sensitivity of some older individuals cannot be ruled out. The Cmax and AUC24 of febuxostat following multiple oral doses of Uloric in geriatric subjects (≥ 65 years) were similar to those in younger subjects (18-40 years) [see Clinical Pharmacology (12.3)].
Renal Impairment
No dose adjustment is necessary in patients with mild or moderate renal impairment (Clcr 30-89 mL per min). The recommended starting dose of Uloric is 40 mg once daily. For patients who do not achieve a sUA less than 6 mg per dL after 2 weeks with 40 mg, Uloric 80 mg is recommended.
There are insufficient data in patients with severe renal impairment (Clcr less than 30 mL per min); therefore, caution should be exercised in these patients [see Clinical Pharmacology (12.3)].
Hepatic Impairment
No dose adjustment is necessary in patients with mild or moderate hepatic impairment (Child-Pugh Class A or B). No studies have been conducted in patients with severe hepatic impairment (Child-Pugh Class C); therefore, caution should be exercised in these patients [see Clinical Pharmacology (12.3)].
Secondary Hyperuricemia
No studies have been conducted in patients with secondary hyperuricemia (including organ transplant recipients); Uloric is not recommended for use in patients whom the rate of urate formation is greatly increased (e.g., malignant disease and its treatment, Lesch-Nyhan syndrome). The concentration of xanthine in urine could, in rare cases, rise sufficiently to allow deposition in the urinary tract.
Overdosage
Uloric was studied in healthy subjects in doses up to 300 mg daily for seven days without evidence of dose-limiting toxicities. No overdose of Uloric was reported in clinical studies. Patients should be managed by symptomatic and supportive care should there be an overdose.
Uloric Description
Uloric (febuxostat) is a xanthine oxidase inhibitor. The active ingredient in Uloric is 2-[3-cyano-4-(2-methylpropoxy) phenyl]-4-methylthiazole-5-carboxylic acid, with a molecular weight of 316.38. The empirical formula is C16H16N2O3S.
The chemical structure is:
Febuxostat is a non-hygroscopic, white crystalline powder that is freely soluble in dimethylformamide; soluble in dimethylsulfoxide; sparingly soluble in ethanol; slightly soluble in methanol and acetonitrile; and practically insoluble in water. The melting range is 205°C to 208°C.
Uloric tablets for oral use contain the active ingredient, febuxostat, and are available in two dosage strengths, 40 mg and 80 mg. Inactive ingredients include lactose monohydrate, microcrystalline cellulose, hydroxypropyl cellulose, sodium croscarmellose, silicon dioxide and magnesium stearate. Uloric tablets are coated with Opadry II, green.
Uloric - Clinical Pharmacology
Mechanism of Action
Uloric, a xanthine oxidase inhibitor, achieves its therapeutic effect by decreasing serum uric acid. Uloric is not expected to inhibit other enzymes involved in purine and pyrimidine synthesis and metabolism at therapeutic concentrations.
Pharmacodynamics
Effect on Uric Acid and Xanthine Concentrations: In healthy subjects, Uloric resulted in a dose dependent decrease in 24-hour mean serum uric acid concentrations, and an increase in 24-hour mean serum xanthine concentrations. In addition, there was a decrease in the total daily urinary uric acid excretion. Also, there was an increase in total daily urinary xanthine excretion. Percent reduction in 24-hour mean serum uric acid concentrations was between 40% to 55% at the exposure levels of 40 mg and 80 mg daily doses.
Effect on Cardiac Repolarization: The effect of Uloric on cardiac repolarization as assessed by the QTc interval was evaluated in normal healthy subjects and in patients with gout. Uloric in doses up to 300 mg daily, at steady state, did not demonstrate an effect on the QTc interval.
Pharmacokinetics
In healthy subjects, maximum plasma concentrations (Cmax) and AUC of febuxostat increased in a dose proportional manner following single and multiple doses of 10 mg to 120 mg. There is no accumulation when therapeutic doses are administered every 24 hours. Febuxostat has an apparent mean terminal elimination half-life (t1/2) of approximately 5 to 8 hours. Febuxostat pharmacokinetic parameters for patients with hyperuricemia and gout estimated by population pharmacokinetic analyses were similar to those estimated in healthy subjects.
Absorption: The absorption of radiolabeled febuxostat following oral dose administration was estimated to be at least 49% (based on total radioactivity recovered in urine). Maximum plasma concentrations of febuxostat occurred between 1 to 1.5 hours post-dose. After multiple oral 40 mg and 80 mg once daily doses, Cmax is approximately 1.6 ± 0.6 mcg per mL (N=30), and 2.6 ± 1.7 mcg per mL (N=227), respectively. Absolute bioavailability of the febuxostat tablet has not been studied.
Following multiple 80 mg once daily doses with a high fat meal, there was a 49% decrease in Cmax and an 18% decrease in AUC, respectively. However, no clinically significant change in the percent decrease in serum uric acid concentration was observed (58% fed vs. 51% fasting). Thus, Uloric may be taken without regard to food.
Concomitant ingestion of an antacid containing magnesium hydroxide and aluminum hydroxide with an 80 mg single dose of Uloric has been shown to delay absorption of febuxostat (approximately 1 hour) and to cause a 31% decrease in Cmax and a 15% decrease in AUC∞. As AUC rather than Cmax was related to drug effect, change observed in AUC was not considered clinically significant. Therefore, Uloric may be taken without regard to antacid use.
Distribution: The mean apparent steady state volume of distribution (Vss/F) of febuxostat was approximately 50 L (CV ~40%). The plasma protein binding of febuxostat is approximately 99.2%, (primarily to albumin), and is constant over the concentration range achieved with 40 mg and 80 mg doses.
Metabolism: Febuxostat is extensively metabolized by both conjugation via uridine diphosphate glucuronosyltransferase (UGT) enzymes including UGT1A1, UGT1A3, UGT1A9, and UGT2B7 and oxidation via cytochrome P450 (CYP) enzymes including CYP1A2, 2C8 and 2C9 and non-P450 enzymes. The relative contribution of each enzyme isoform in the metabolism of febuxostat is not clear. The oxidation of the isobutyl side chain leads to the formation of four pharmacologically active hydroxy metabolites, all of which occur in plasma of humans at a much lower extent than febuxostat.
In urine and feces, acyl glucuronide metabolites of febuxostat (~35% of the dose), and oxidative metabolites, 67M-1 (~10% of the dose), 67M-2 (~11% of the dose), and 67M-4, a secondary metabolite from 67M-1, (~14% of the dose) appeared to be the major metabolites of febuxostat in vivo.
Elimination: Febuxostat is eliminated by both hepatic and renal pathways. Following an 80 mg oral dose of 14C-labeled febuxostat, approximately 49% of the dose was recovered in the urine as unchanged febuxostat (3%), the acyl glucuronide of the drug (30%), its known oxidative metabolites and their conjugates (13%), and other unknown metabolites (3%). In addition to the urinary excretion, approximately 45% of the dose was recovered in the feces as the unchanged febuxostat (12%), the acyl glucuronide of the drug (1%), its known oxidative metabolites and their conjugates (25%), and other unknown metabolites (7%).
The apparent mean terminal elimination half-life (t1/2) of febuxostat was approximately 5 to 8 hours.
Special Populations
Pediatric Use: The pharmacokinetics of Uloric in patients under the age of 18 years have not been studied.
Geriatric Use: The Cmax and AUC of febuxostat and its metabolites following multiple oral doses of Uloric in geriatric subjects (≥ 65 years) were similar to those in younger subjects (18-40 years). In addition, the percent decrease in serum uric acid concentration was similar between elderly and younger subjects. No dose adjustment is necessary in geriatric patients [see Use in Specific Populations (8.5)].
Renal Impairment: Following multiple 80 mg doses of Uloric in healthy subjects with mild (Clcr 50-80 mL per min), moderate (Clcr 30-49 mL per min) or severe renal impairment (Clcr 10-29 mL per min), the Cmax of febuxostat did not change relative to subjects with normal renal function (Clcr greater than 80 mL per min). AUC and half-life of febuxostat increased in subjects with renal impairment in comparison to subjects with normal renal function, but values were similar among three renal impairment groups. Mean febuxostat AUC values were up to 1.8 times higher in subjects with renal impairment compared to those with normal renal function. Mean Cmax and AUC values for 3 active metabolites increased up to 2- and 4-fold, respectively. However, the percent decrease in serum uric acid concentration for subjects with renal impairment was comparable to those with normal renal function (58% in normal renal function group and 55% in the severe renal function group).
No dose adjustment is necessary in patients with mild to moderate renal impairment [see Dosage and Administration (2) and Use in Specific Populations (8.6)]. The recommended starting dose of Uloric is 40 mg once daily. For patients who do not achieve a sUA less than 6 mg per dL after 2 weeks with 40 mg, Uloric 80 mg is recommended. There is insufficient data in patients with severe renal impairment; caution should be exercised in those patients [see Use in Specific Populations (8.6)].
Uloric has not been studied in end stage renal impairment patients who are on dialysis.
Hepatic Impairment: Following multiple 80 mg doses of Uloric in patients with mild (Child-Pugh Class A) or moderate (Child-Pugh Class B) hepatic impairment, an average of 20-30% increase was observed for both Cmax and AUC24 (total and unbound) in hepatic impairment groups compared to subjects with normal hepatic function. In addition, the percent decrease in serum uric acid concentration was comparable between different hepatic groups (62% in healthy group, 49% in mild hepatic impairment group, and 48% in moderate hepatic impairment group). No dose adjustment is necessary in patients with mild or moderate hepatic impairment. No studies have been conducted in subjects with severe hepatic impairment (Child-Pugh Class C); caution should be exercised in those patients [see Use in Specific Populations (8.7)].
Gender: Following multiple oral doses of Uloric, the Cmax and AUC24 of febuxostat were 30% and 14% higher in females than in males, respectively. However, weight-corrected Cmax and AUC were similar between the genders. In addition, the percent decrease in serum uric acid concentrations was similar between genders. No dose adjustment is necessary based on gender.
Race: No specific pharmacokinetic study was conducted to investigate the effects of race.
Drug-Drug Interactions
Effect of Uloric on Other Drugs
Xanthine Oxidase Substrate Drugs-Azathioprine, Mercaptopurine, and Theophylline: Febuxostat is an XO inhibitor. A drug-drug interaction study evaluating the effect of Uloric upon the pharmacokinetics of theophylline (an XO substrate) in healthy subjects showed that co-administration of febuxostat with theophylline resulted in an approximately 400-fold increase in the amount of 1-methylxanthine, one of the major metabolites of theophylline, excreted in the urine. Since the long-term safety of exposure to 1-methylxanthine in humans is unknown, use with caution when co-administering febuxostat with theophylline.
Drug interaction studies of Uloric with other drugs that are metabolized by XO (e.g., mercaptopurine and azathioprine) have not been conducted. Inhibition of XO by Uloric may cause increased plasma concentrations of these drugs leading to toxicity. Uloric is contraindicated in patients being treated with azathioprine or mercaptopurine [see Contraindications (4) and Drug Interactions (7)].
Azathioprine and mercaptopurine undergo metabolism via three major metabolic pathways, one of which is mediated by XO. Although Uloric drug interaction studies with azathioprine and mercaptopurine have not been conducted, concomitant administration of allopurinol [a xanthine oxidase inhibitor] with azathioprine or mercaptopurine has been reported to substantially increase plasma concentrations of these drugs. Because Uloric is a xanthine oxidase inhibitor, it could inhibit the XO-mediated metabolism of azathioprine and mercaptopurine leading to increased plasma concentrations of azathioprine or mercaptopurine that could result in severe toxicity.
P450 Substrate Drugs: In vitro studies have shown that febuxostat does not inhibit P450 enzymes CYP1A2, 2C9, 2C19, 2D6, or 3A4 and it also does not induce CYP1A2, 2B6, 2C9, 2C19, or 3A4 at clinically relevant concentrations. As such, pharmacokinetic interactions between Uloric and drugs metabolized by these CYP enzymes are unlikely.
Effect of Other Drugs on Uloric
Febuxostat is metabolized by conjugation and oxidation via multiple metabolizing enzymes. The relative contribution of each enzyme isoform is not clear. Drug interactions between Uloric and a drug that inhibits or induces one particular enzyme isoform is in general not expected.
In Vivo Drug Interaction Studies
Theophylline: No dose adjustment is necessary for theophylline when co-administered with Uloric. Administration of Uloric (80 mg once daily) with theophylline resulted in an increase of 6% in Cmax and 6.5% in AUC of theophylline. These changes were not considered statistically significant. However, the study also showed an approximately 400-fold increase in the amount of 1-methylxanthine (one of the major theophylline metabolites) excreted in urine as a result of XO inhibition by Uloric. The safety of long-term exposure to 1-methylxanthine has not been evaluated. This should be taken into consideration when deciding to co-administer Uloric and theophylline.
Colchicine: No dose adjustment is necessary for either Uloric or colchicine when the two drugs are co-administered. Administration of Uloric (40 mg once daily) with colchicine (0.6 mg twice daily) resulted in an increase of 12% in Cmax and 7% in AUC24 of febuxostat. In addition, administration of colchicine (0.6 mg twice daily) with Uloric (120 mg daily) resulted in less than 11% change in Cmax or AUC of colchicine for both AM and PM doses. These changes were not considered clinically significant.
Naproxen: No dose adjustment is necessary for Uloric or naproxen when the two drugs are co-administered. Administration of Uloric (80 mg once daily) with naproxen (500 mg twice daily) resulted in a 28% increase in Cmax and a 40% increase in AUC of febuxostat. The increases were not considered clinically significant. In addition, there were no significant changes in the Cmax or AUC of naproxen (less than 2%).
Indomethacin: No dose adjustment is necessary for either Uloric or indomethacin when these two drugs are co-administered. Administration of Uloric (80 mg once daily) with indomethacin (50 mg twice daily) did not result in any significant changes in Cmax or AUC of febuxostat or indomethacin (less than 7%).
Hydrochlorothiazide: No dose adjustment is necessary for Uloric when co-administered with hydrochlorothiazide. Administration of Uloric (80 mg) with hydrochlorothiazide (50 mg) did not result in any clinically significant changes in Cmax or AUC of febuxostat (less than 4%), and serum uric acid concentrations were not substantially affected.
Warfarin: No dose adjustment is necessary for warfarin when co-administered with Uloric. Administration of Uloric (80 mg once daily) with warfarin had no effect on the pharmacokinetics of warfarin in healthy subjects. INR and Factor VII activity were also not affected by the co-administration of Uloric.
Desipramine: Co-administration of drugs that are CYP2D6 substrates (such as desipramine) with Uloric are not expected to require dose adjustment. Febuxostat was shown to be a weak inhibitor of CYP2D6 in vitro and in vivo. Administration of Uloric (120 mg once daily) with desipramine (25 mg) resulted in an increase in Cmax (16%) and AUC (22%) of desipramine, which was associated with a 17% decrease in the 2-hydroxydesipramine to desipramine metabolic ratio (based on AUC).
Nonclinical Toxicology
Carcinogenesis, Mutagenesis, Impairment of Fertility
Carcinogenesis: Two-year carcinogenicity studies were conducted in F344 rats and B6C3F1 mice. Increased transitional cell papilloma and carcinoma of urinary bladder was observed at 24 mg per kg (25 times the human plasma exposure at maximum recommended human dose of 80 mg per day) and 18.75 mg per kg (12.5 times the human plasma exposure at 80 mg per day) in male rats and female mice, respectively. The urinary bladder neoplasms were secondary to calculus formation in the kidney and urinary bladder.
Mutagenesis: Febuxostat showed a positive mutagenic response in a chromosomal aberration assay in a Chinese hamster lung fibroblast cell line with and without metabolic activation in vitro. Febuxostat was negative in the in vitro Ames assay and chromosomal aberration test in human peripheral lymphocytes, and L5178Y mouse lymphoma cell line, and in vivo tests in mouse micronucleus, rat unscheduled DNA synthesis and rat bone marrow cells.
Impairment of Fertility: Febuxostat at oral doses up to 48 mg per kg per day (approximately 35 times the human plasma exposure at 80 mg per day) had no effect on fertility and reproductive performance of male and female rats.
Animal Toxicology
A 12-month toxicity study in beagle dogs showed deposition of xanthine crystals and calculi in kidneys at 15 mg per kg (approximately 4 times the human plasma exposure at 80 mg per day). A similar effect of calculus formation was noted in rats in a six-month study due to deposition of xanthine crystals at 48 mg per kg (approximately 35 times the human plasma exposure at 80 mg per day).
Clinical Studies
A serum uric acid level of less than 6 mg per dL is the goal of anti-hyperuricemic therapy and has been established as appropriate for the treatment of gout.
Management of Hyperuricemia in Gout
The efficacy of Uloric was demonstrated in three randomized, double-blind, controlled trials in patients with hyperuricemia and gout. Hyperuricemia was defined as a baseline serum uric acid level ≥ 8 mg per dL.
Study 1 randomized patients to: Uloric 40 mg daily, Uloric 80 mg daily, or allopurinol (300 mg daily for patients with estimated creatinine clearance (Clcr) ≥ 60 mL per min or 200 mg daily for patients with estimated Clcr ≥ 30 mL per min and ≤ 59 mL per min). The duration of Study 1 was 6 months.
Study 2 randomized patients to: placebo, Uloric 80 mg daily, Uloric 120 mg daily, Uloric 240 mg daily or allopurinol (300 mg daily for patients with a baseline serum creatinine ≤ 1.5 mg per dL or 100 mg daily for patients with a baseline serum creatinine greater than 1.5 mg per dL and ≤ 2 mg per dL). The duration of Study 2 was 6 months.
Study 3, a 1-year study, randomized patients to: Uloric 80 mg daily, Uloric 120 mg daily, or allopurinol 300 mg daily. Subjects who completed Study 2 and Study 3 were eligible to enroll in a phase 3 long-term extension study in which subjects received treatment with Uloric for over three years.
In all three studies, subjects received naproxen 250 mg twice daily or colchicine 0.6 mg once or twice daily for gout flare prophylaxis. In Study 1 the duration of prophylaxis was 6 months; in Study 2 and Study 3 the duration of prophylaxis was 8 weeks.
The efficacy of Uloric was also evaluated in a 4 week dose ranging study which randomized patients to: placebo, Uloric 40 mg daily, Uloric 80 mg daily, or Uloric 120 mg daily. Subjects who completed this study were eligible to enroll in a long-term extension study in which subjects received treatment with Uloric for up to five years.
Patients in these studies were representative of the patient population for which Uloric use is intended. Table 2 summarizes the demographics and baseline characteristics for the subjects enrolled in the studies.
| Table 2: Patient Demographics and Baseline Characteristics in Study 1, Study 2 and Study 3 |
|---|
| Male |
95% |
| Race: |
Caucasian |
80% |
|
African American |
10% |
| Ethnicity: |
Hispanic or Latino |
7% |
| Alcohol User |
67% |
Mild to Moderate Renal Insufficiency
[percent with estimated Clcr less than 90 mL per min] |
59% |
| History of Hypertension |
49% |
| History of Hyperlipidemia |
38% |
| BMI ≥ 30 kg per m2 |
63% |
| Mean BMI |
33 kg per m2 |
| Baseline sUA ≥ 10 mg per dL |
36% |
| Mean baseline sUA |
9.7 mg per dL |
| Experienced a gout flare in previous year |
85% |
Serum Uric Acid Level less than 6 mg per dL at Final Visit: Uloric 80 mg was superior to allopurinol in lowering serum uric acid to less than 6 mg per dL at the final visit. Uloric 40 mg daily, although not superior to allopurinol, was effective in lowering serum uric acid to less than 6 mg per dL at the final visit (Table 3).
| Table 3: Proportion of Patients with Serum Uric Acid Levels Less Than 6 mg per dL at Final Visit |
|---|
|
|
|
|
|
Difference in Proportion
(95% CI) |
|---|
| Study |
Uloric
40 mg daily |
Uloric
80 mg daily |
allopurinol |
Placebo |
Uloric 40 mg
vs
allopurinol |
Uloric 80 mg
vs
allopurinol |
|---|
|
Study 1
(6 months)
(N=2268) |
45% |
67% |
42% |
|
3%
(-2%, 8%) |
25%
(20%, 30%) |
Study 2
(6 months)
(N=643) |
|
72% |
39% |
1% |
|
33%
(26%, 42%) |
Study 3
(12 months)
(N=491) |
|
74% |
36% |
|
|
38%
(30%, 46%) |
In 76% of Uloric 80 mg patients, reduction in serum uric acid levels to less than 6 mg per dL was noted by the Week 2 visit. Average serum uric acid levels were maintained at 6 mg per dL or below throughout treatment in 83% of these patients.
In all treatment groups, fewer subjects with higher baseline serum urate levels (≥ 10 mg per dL) and/or tophi achieved the goal of lowering serum uric acid to less than 6 mg per dL at the final visit; however, a higher proportion achieved a serum uric acid less than 6 mg per dL with Uloric 80 mg than with Uloric 40 mg or allopurinol.
Study 1 evaluated efficacy in patients with mild to moderate renal impairment (i.e., baseline estimated Clcr less than 90 mL per minute). The results in this sub-group of patients are shown in Table 4.
| Table 4: Proportion of Patients with Serum Uric Acid Levels Less Than 6 mg per dL in Patients with Mild or Moderate Renal Impairment at Final Visit |
|---|
|
|
|
Difference in Proportion
(95% CI) |
|---|
Uloric
40 mg daily
(N=479) |
Uloric
80 mg daily
(N=503) |
allopurinol
300 mg daily
(N=501) |
Uloric 40 mg vs allopurinol |
Uloric 80 mg vs allopurinol |
|---|
|
| 50% |
72% |
42% |
7%
(1%, 14%) |
29%
(23%, 35%) |
How Supplied/Storage and Handling
Uloric 40 mg tablets are light green to green in color, round shaped, debossed with "TAP" on one side and "40" on the other side and supplied as:
| NDC Number |
Size |
|---|
| 64764-918-11 |
Hospital Unit Dose Pack of 100 Tablets |
| 64764-918-30 |
Bottle of 30 Tablets |
| 64764-918-90 |
Bottle of 90 Tablets |
| 64764-918-18 |
Bottle of 500 Tablets |
Uloric 80 mg tablets are light green to green in color, teardrop shaped, debossed with "TAP" on one side and "80" on the other side and supplied as:
| NDC Number |
Size |
|---|
| 64764-677-11 |
Hospital Unit Dose Pack of 100 Tablets |
| 64764-677-30 |
Bottle of 30 Tablets |
|
