Febuxostat
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Chronic management of hyperuricaemia in gout — limited to patients who have an inadequate response to maximally titrated allopurinol, are intolerant to allopurinol, or for whom allopurinol is not advisable | Adults | Long-term urate-lowering monotherapy | FDA Approved |
Febuxostat was first approved by the FDA in 2009 as a non-purine selective xanthine oxidase inhibitor for gout. Following the 2018 CARES trial, which demonstrated higher cardiovascular mortality compared with allopurinol in patients with established CV disease, the FDA added a boxed warning in 2019 and restricted its indication to second-line use. The brand name Uloric was discontinued in the US in early 2025, though generic febuxostat remains available. Febuxostat is not recommended for asymptomatic hyperuricaemia or secondary hyperuricaemia associated with malignancy or Lesch-Nyhan syndrome. The ACR 2020 guideline conditionally recommends allopurinol over febuxostat as first-line ULT, reserving febuxostat for allopurinol-intolerant or allopurinol-inadequate responders.
Dosing
Adult Dosing by Clinical Scenario
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Gout — second-line after allopurinol failure or intolerance | 40 mg once daily | 40–80 mg once daily | 80 mg/day | If SUA not <6 mg/dL after 2 weeks at 40 mg, increase to 80 mg Take with or without food; no regard to meals |
| Gout with mild–moderate renal impairment (CrCl 30–89 mL/min) | 40 mg once daily | 40–80 mg once daily | 80 mg/day | No dose adjustment required per PI Minimal renal clearance of parent drug (~1–6%) |
| Gout with severe renal impairment (CrCl <30 mL/min) | 40 mg once daily | Use with caution | Insufficient data | PI states insufficient data; exercise caution Some studies suggest efficacy and tolerability are maintained |
Gout flares occur frequently when starting febuxostat (up to 43% in trials) due to urate mobilisation from tissue deposits. Concurrent flare prophylaxis with colchicine or an NSAID is recommended for up to 6 months after initiation. Do not discontinue febuxostat during an acute flare — manage the flare concurrently and continue urate-lowering therapy.
Due to the FDA boxed warning for increased cardiovascular death, febuxostat should only be prescribed to patients who have had an inadequate response to a maximally titrated dose of allopurinol, who are intolerant to allopurinol, or for whom allopurinol treatment is not advisable. Assess cardiovascular risks and benefits before initiating or continuing therapy.
Pharmacology
Mechanism of Action
Febuxostat is a non-purine, thiazolecarboxylic acid derivative that acts as a selective inhibitor of xanthine oxidase (XO). Unlike allopurinol, which is a purine analogue that requires oxidation by XO for activity, febuxostat occupies the molybdenum-pterin substrate channel of XO through tight binding, inhibiting both the oxidised and reduced forms of the enzyme. This results in potent, dose-dependent reduction of serum urate by blocking the conversion of hypoxanthine to xanthine and xanthine to uric acid. At therapeutic doses, febuxostat achieves greater and more sustained urate lowering than commonly used doses of allopurinol.
The selectivity of febuxostat for xanthine oxidase is high; it does not significantly inhibit other enzymes involved in purine or pyrimidine metabolism at therapeutic concentrations. As with all xanthine oxidase inhibitors, reducing urate production also decreases urinary uric acid excretion, though urinary xanthine and hypoxanthine levels increase reciprocally.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | Rapidly absorbed; Tmax 1–1.5 h; estimated oral availability ~85%; high-fat meal decreases Cmax by 49% and AUC by 18% but no clinically significant effect on SUA reduction | May be taken with or without food; no clinically relevant food effect on efficacy |
| Distribution | Vss/F ~50 L; protein binding ~99.2% (primarily albumin); constant across concentration range | High protein binding limits displacement interactions but also limits dialyzability |
| Metabolism | Extensively hepatic: acyl glucuronidation via UGT1A1, UGT1A3, UGT1A9, UGT2B7 (~40%); oxidation via CYP1A2, CYP2C8, CYP2C9 and non-CYP enzymes (~35%); four active hydroxyl metabolites (much lower plasma levels than parent) | Multiple metabolic pathways reduce risk of single-enzyme drug interactions; no single CYP dominates |
| Elimination | t½ ~5–8 h (apparent terminal); ~49% urine (3% unchanged, 30% acyl glucuronide, 13% oxidative metabolites); ~45% faeces; no significant accumulation with daily dosing | Dual hepatic and renal elimination; mild–moderate renal impairment does not significantly alter PK |
Side Effects
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Gout flares | Up to 43% (in clinical trials) | Due to urate mobilisation; not a reason to stop; co-prescribe colchicine or NSAID prophylaxis for up to 6 months |
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Liver function abnormalities | 6.6% (40 mg); 4.6% (80 mg) vs 0.7% placebo | Most common reason for discontinuation (1.2–1.8%); monitor LFTs; hepatic failure (some fatal) reported postmarketing |
| Nausea | 1.1–1.3% | Mild; dose-independent |
| Arthralgia | 0.7–1.1% | May overlap with gout flare symptoms; distinguish from drug-induced joint pain |
| Rash | 0.5–1.6% | Any rash warrants evaluation; rare progression to SJS/TEN reported postmarketing |
| Dizziness | >1% | Not >0.5% above placebo in trials; counsel about driving |
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Cardiovascular death (BOXED WARNING) | 4.3% vs 3.2% allopurinol (HR 1.34) in CARES | Variable; median follow-up 32 months | Reserve for allopurinol-intolerant/inadequate patients; assess CV risk before and during treatment; consider switching to alternative ULT if new CV event |
| Hepatic failure (including fatal cases) | Rare (postmarketing) | Variable | Promptly interrupt febuxostat; investigate aetiology; permanently discontinue if liver injury confirmed without alternate cause |
| SJS / TEN / DRESS | Rare (postmarketing) | Weeks after initiation | Immediate permanent discontinuation; dermatology referral; supportive care |
| Rhabdomyolysis | Rare (postmarketing) | Variable | Discontinue; check CK and renal function; IV hydration |
| Agranulocytosis / pancytopenia | Rare (postmarketing) | Variable | Discontinue; urgent CBC; haematology referral |
| Reason | Incidence | Context |
|---|---|---|
| Elevated LFTs | 1.2–1.8% | Most common cause of drug-related discontinuation in pivotal trials |
| Gout flares | Common but not a recommended reason to stop | Early flares reflect efficacy (urate mobilisation); continue treatment with concurrent flare management |
| Rash | Uncommon but mandates evaluation | Any rash should be assessed for SJS/TEN given postmarketing reports |
Liver function abnormalities are the most common adverse reaction with febuxostat and the leading cause of treatment discontinuation. Postmarketing cases of fatal hepatic failure have been reported. Obtain baseline LFTs and recheck periodically. Promptly interrupt febuxostat if liver injury signs develop (anorexia, jaundice, dark urine, right upper quadrant pain). Permanently discontinue if liver injury is confirmed and no alternative aetiology is identified.
Drug Interactions
Febuxostat is metabolised by multiple UGT and CYP isoforms, making single-enzyme drug interactions unlikely. However, its potent inhibition of xanthine oxidase creates critical interactions with purine analogues metabolised by the same pathway.
Monitoring
- Serum Uric AcidAt 2 weeks (to guide dose titration); then q3–6 months
RoutineTarget <6 mg/dL. If not achieved at 40 mg after 2 weeks, increase to 80 mg. Continued monitoring ensures sustained target attainment. - Liver Function TestsBaseline; periodically during treatment
RoutineALT, AST, ALP, total bilirubin. LFT abnormalities are the most common adverse effect (up to 6.6%). Fatal hepatic failure reported postmarketing. Interrupt if liver injury signs develop. - Cardiovascular StatusBaseline assessment; ongoing clinical vigilance
RoutineAssess CV risk factors and history before initiation. Monitor for new CV symptoms (chest pain, dyspnoea, syncope). Consider switching to alternative ULT if new CV event occurs (ACR 2020). - Renal FunctionBaseline; periodically
RoutineSerum creatinine and eGFR. Caution in severe impairment (CrCl <30 mL/min) due to insufficient data. Tubulointerstitial nephritis reported postmarketing. - Skin AssessmentEvery visit; patient self-monitoring
Trigger-basedPostmarketing reports of SJS, TEN, and DRESS. Caution in patients with prior hypersensitivity to allopurinol (cross-sensitivity possible). Discontinue at first sign of rash. - Drug Interaction ReviewAt initiation and prescription changes
Trigger-basedConfirm no concurrent azathioprine, mercaptopurine, or didanosine. Review theophylline and repaglinide use.
Contraindications & Cautions
Absolute Contraindications
- Concurrent use of azathioprine or mercaptopurine — predictable life-threatening myelosuppression from XO inhibition of 6-MP metabolism.
Relative Contraindications (Specialist Input Recommended)
- Established major cardiovascular disease (prior MI, stroke, unstable angina) — FDA boxed warning: higher CV death in CARES trial. Only prescribe if no alternative ULT is suitable; document risk-benefit discussion.
- Severe hepatic impairment (Child-Pugh C) — not studied; postmarketing fatal hepatic failure reported.
- Severe renal impairment (CrCl <30 mL/min) — insufficient data per PI; use with caution if benefits outweigh risks.
Use with Caution
- Patients with CV risk factors — consider prophylactic low-dose aspirin per FDA guidance; monitor for CV events.
- Prior allopurinol hypersensitivity — postmarketing reports of cross-reactivity with skin reactions; heightened monitoring advised.
- Pregnancy — insufficient human data; animal studies showed no teratogenicity at therapeutic exposures but neonatal effects at high doses.
- Lactation — present in rat milk; unknown in human milk; high protein binding may limit transfer but caution advised.
- Lactose intolerance — tablets contain lactose monohydrate as excipient.
In the CARES trial (N=6,190), gout patients with established cardiovascular disease treated with febuxostat experienced a higher rate of CV death compared with those treated with allopurinol (4.3% vs 3.2%; HR 1.34, 95% CI 1.03–1.73). Sudden cardiac death was the most common cause of CV death in the febuxostat group (83 vs 56 events). All-cause mortality was also higher (7.8% vs 6.4%; HR 1.22, 95% CI 1.01–1.47). The FAST trial (N=6,128) subsequently found febuxostat was noninferior to allopurinol for MACE with no increased all-cause or CV mortality, but the FDA boxed warning remains in effect.
Patient Counselling
Purpose of Therapy
Febuxostat works by reducing the amount of uric acid the body produces. It is prescribed specifically for people whose gout has not been adequately controlled by allopurinol, or who cannot take allopurinol. It is taken once daily and is a long-term treatment — it does not treat individual gout attacks but prevents them from occurring over time by keeping uric acid levels low.
How to Take
Take febuxostat once daily with or without food. Your doctor will typically start at 40 mg per day and may increase to 80 mg after 2 weeks if needed based on blood test results. Continue taking febuxostat even during a gout flare. Do not stop the medicine without speaking to your doctor.
Sources
- Uloric (febuxostat) Prescribing Information. Takeda Pharmaceuticals America, Inc. Revised February 2019. FDAFDA-approved PI with boxed warning for CV death; source for dosing, adverse reactions, and drug interactions.
- FDA Drug Safety Communication: FDA adds boxed warning for increased risk of death with gout medicine Uloric (febuxostat). February 21, 2019. FDA.govFDA safety communication establishing the boxed warning and prescribing restrictions based on CARES trial results.
- White WB, Saag KG, Becker MA, et al. Cardiovascular safety of febuxostat or allopurinol in patients with gout. N Engl J Med. 2018;378(13):1200–1210. doi:10.1056/NEJMoa1710895CARES trial: demonstrated higher CV death (HR 1.34) and all-cause mortality (HR 1.22) with febuxostat vs allopurinol in gout patients with established CV disease.
- Mackenzie IS, Ford I, Nuki G, et al. Long-term cardiovascular safety of febuxostat compared with allopurinol in patients with gout (FAST). Lancet. 2020;396(10264):1745–1757. doi:10.1016/S0140-6736(20)32234-0FAST trial: demonstrated febuxostat noninferior to allopurinol for MACE; no increased all-cause or CV mortality; better retention than CARES.
- Becker MA, Schumacher HR Jr, Wortmann RL, et al. Febuxostat compared with allopurinol in patients with hyperuricemia and gout. N Engl J Med. 2005;353(23):2450–2461. doi:10.1056/NEJMoa050373FACT trial: established febuxostat 80 mg and 120 mg as superior to allopurinol 300 mg for achieving target SUA in gout patients.
- Schumacher HR Jr, Becker MA, Wortmann RL, et al. Effects of febuxostat versus allopurinol and placebo in reducing serum urate in subjects with hyperuricemia and gout. Arthritis Rheum. 2008;59(11):1540–1548. doi:10.1002/art.24209APEX trial: demonstrated dose-response for febuxostat (80, 120, 240 mg) vs allopurinol 300 mg and placebo in urate lowering.
- Becker MA, Schumacher HR, Espinoza LR, et al. The urate-lowering efficacy and safety of febuxostat in the treatment of the hyperuricemia of gout: the CONFIRMS trial. Arthritis Res Ther. 2010;12(2):R63. doi:10.1186/ar2978CONFIRMS trial: largest pre-approval trial (N=2,269); confirmed febuxostat 40 mg comparable to allopurinol 300 mg, and 80 mg superior, for achieving target SUA.
- FitzGerald JD, Dalbeth N, Mikuls T, et al. 2020 American College of Rheumatology guideline for management of gout. Arthritis Care Res. 2020;72(6):744–760. doi:10.1002/acr.24180Current ACR guideline conditionally recommending allopurinol over febuxostat as first-line ULT; reserves febuxostat for allopurinol-intolerant or inadequate responders.
- Okamoto K, Eger BT, Nishino T, et al. An extremely potent inhibitor of xanthine oxidoreductase: crystal structure of the enzyme-inhibitor complex and mechanism of inhibition. J Biol Chem. 2003;278(3):1848–1855. doi:10.1074/jbc.M208307200Structural study demonstrating febuxostat’s binding to the molybdenum-pterin substrate channel of XO, explaining its potent and selective inhibition.
- Takano Y, Hase-Aoki K, Horiuchi H, et al. Selectivity of febuxostat, a novel non-purine inhibitor of xanthine oxidase/xanthine dehydrogenase. Life Sci. 2005;76(16):1835–1847. doi:10.1016/j.lfs.2004.10.031Demonstrated febuxostat’s high selectivity for XO/XDH with no significant inhibition of other purine/pyrimidine metabolic enzymes.
- Khosravan R, Grabowski BA, Wu JT, et al. Pharmacokinetics, pharmacodynamics and safety of febuxostat, a non-purine selective inhibitor of xanthine oxidase, in a dose escalation study in healthy subjects. Clin Pharmacokinet. 2006;45(8):821–841. doi:10.2165/00003088-200645080-00006Phase I dose-escalation study establishing PK parameters: rapid absorption (Tmax 0.5–1.3 h), Vd 33–64 L, t½ 1.3–15.8 h, linear PK in 10–120 mg range.
- Stocker SL, Graham GG, McLachlan AJ, et al. Clinical pharmacokinetics and pharmacodynamics of febuxostat. Clin Pharmacokinet. 2017;56(5):459–475. doi:10.1007/s40262-016-0466-4Comprehensive PK/PD review: oral availability ~85%, CL/F 10.5 L/h, Vss/F 48 L, protein binding 99.2%, terminal t½ 9.4 h; dual hepatic-renal elimination.