Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
LOPURIN vs FEBUXOSTAT
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
LOPURIN is a brand name for allopurinol, a xanthine oxidase inhibitor. It reduces uric acid production by inhibiting the conversion of hypoxanthine to xanthine and xanthine to uric acid.
Febuxostat is a non-purine selective inhibitor of xanthine oxidase (XO). It inhibits both oxidized and reduced forms of XO, thereby reducing the conversion of hypoxanthine to xanthine and xanthine to uric acid, leading to decreased serum uric acid levels.
Gout prophylaxis,Management of hyperuricemia in patients with cancer undergoing chemotherapy,Prevention of recurrent calcium oxalate calculi in patients with hyperuricuria
Chronic management of hyperuricemia in patients with gout,Off-label: Prevention of tumor lysis syndrome,Off-label: Management of hyperuricemia in kidney transplant recipients
200-600 mg orally once daily, typically starting at 300 mg/day and adjusting based on serum urate levels.
40 mg orally once daily; may increase to 80 mg orally once daily if serum urate goal not achieved after 2 weeks.
Allopurinol: 1-2 hours; oxypurinol: 18-30 hours (renal function dependent). Accumulation in renal failure; half-life of oxypurinol may exceed 100 hours in ESRD.
Terminal elimination half-life: 5-8 hours in healthy subjects; prolonged in renal impairment (e.g., up to 9.6 hours in moderate impairment). Clinical context: dosing interval is once daily, consistent with half-life.
Primarily hepatic via aldehyde oxidase to oxypurinol (alloxanthine), which is also active; minor metabolism by xanthine oxidase.
Primarily metabolized by conjugation via UDP-glucuronosyltransferases (UGT1A1, UGT1A3, UGT1A9, and UGT2B7) and oxidation via cytochrome P450 (CYP) enzymes, including CYP1A2, CYP2C8, and CYP2C9, with minor contribution from CYP3A4/5.
Renal (primarily as unchanged drug and active metabolite oxypurinol): ~70% urinary excretion; remainder biliary/fecal. Dose adjustment required in renal impairment.
Renal: 1-3% unchanged; biliary/fecal: ~50% as metabolites (acyl glucuronides, oxidative metabolites); other: ~49% metabolized and eliminated via multiple pathways including biliary and direct intestinal excretion of unchanged drug.
Allopurinol: <1%; oxypurinol: ~20% (primarily to albumin). Negligible displacement interactions.
99% (primarily to albumin; minor binding to alpha-1-acid glycoprotein).
Allopurinol: ~1.6 L/kg; oxypurinol: ~0.6 L/kg. Indicates extensive tissue distribution, including renal and hepatic tissues.
Approximately 0.7 L/kg (indicating distribution into total body water; not extensively tissue-bound).
Oral allopurinol: ~80% (mean); conversion to oxypurinol reduces systemic availability of parent drug. Food delays absorption but does not affect extent.
Oral: at least 49% (absolute bioavailability not established; estimated based on mass balance studies).
For GFR 10-20 m L/min: 200 mg/day; GFR <10 m L/min: 100 mg/day or avoid use; consider alternative in severe impairment.
No dose adjustment required for mild to moderate renal impairment (e GFR 30-89 m L/min). For severe renal impairment (e GFR <30 m L/min), limited data; use with caution, not recommended in dialysis.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use or reduce by 75%.
Child-Pugh Class A or B: no dose adjustment. Child-Pugh Class C: not recommended (no studies).
Children 6-10 years: 100 mg orally once daily; 11-16 years: 200-300 mg orally once daily; adjust based on serum urate.
Not approved for pediatric use; safety and efficacy not established.
Start at lower end of dosing range (100-200 mg/day) due to age-related renal decline; monitor renal function and urate levels.
No specific dose adjustment required; use with caution due to potential for decreased renal function.
No FDA black box warning.
Increased risk of cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, and urgent revascularization in patients with established cardiovascular disease (based on the CARES trial). Febuxostat should be avoided in patients with a history of myocardial infarction or stroke, unless no other therapy is appropriate.
Hypersensitivity syndrome (DRESS) may occur; discontinue at first sign of rash,Acute gout flares may occur upon initiation; prophylactic colchicine or NSAIDs recommended,Renal impairment requires dose adjustment; increase doses cautiously,Monitor liver function; hepatotoxicity reported,Bone marrow suppression (leukopenia, thrombocytopenia) may occur,Anticoagulant effect of warfarin may be enhanced
Cardiovascular events (see black box warning); hepatotoxicity (elevated liver enzymes, hepatic failure); gout flares upon initiation (prophylaxis recommended); renal impairment (dose adjustment for severe impairment); hypersensitivity reactions (including Stevens-Johnson syndrome); thyroid function abnormalities (elevated TSH).
Hypersensitivity to allopurinol or any component,Concurrent use with azathioprine or mercaptopurine unless dose reduction is implemented
Concurrent use with azathioprine, 6-mercaptopurine, or theophylline (due to risk of toxicity); severe renal impairment (Cr Cl <30 m L/min) based on trial data; history of myocardial infarction or stroke (relative contraindication per FDA).
Avoid high-purine foods (organ meats, sardines, anchovies, shellfish, red meat). Limit alcohol intake, particularly beer and spirits. Maintain adequate hydration. No significant food-drug interactions reported.
No specific food interactions are reported, but high-purine foods (red meat, organ meats, shellfish) and alcohol may increase serum urate and counteract drug efficacy; advise moderation and limit intake during therapy.
FDA Pregnancy Category D. First trimester: risk of congenital heart defects, cleft palate, and hypospadias based on animal studies and limited human data. Second and third trimesters: risk of fetal renal dysfunction, oligohydramnios, and neonatal renal impairment due to fetal renin-angiotensin system suppression.
Pregnancy Category C. No adequate studies in pregnant women. In animal studies, febuxostat caused developmental toxicity (reduced fetal weight, increased skeletal variations) at maternal toxic doses. First trimester: unknown risk; avoid unless benefits outweigh risks. Second/third trimester: limited data; potential for fetal harm based on animal findings.
Small amounts of LOPURIN are excreted in breast milk. M/P ratio is approximately 0.2. The American Academy of Pediatrics considers the drug compatible with breastfeeding, but caution is advised due to potential for infant renal effects. Monitor infant for hypotension and renal function.
Excretion in human milk unknown; M/P ratio not determined. Due to potential for serious adverse reactions in nursing infants, breastfeeding is not recommended during therapy.
Increased plasma volume during pregnancy may reduce concentrations; dose adjustments are not routinely recommended due to variable pharmacokinetics. However, if blood pressure control is inadequate, consider increasing the dose under close monitoring. Postpartum, reduce dose to prepregnancy level to avoid hypotension.
No specific pharmacokinetic data in pregnancy. Due to potential teratogenicity, avoid in pregnancy. If use is unavoidable, no dose adjustment studies exist; use lowest effective dose with caution.
Allopurinol is a xanthine oxidase inhibitor. Initiate at low dose (100 mg/day) and titrate to reduce risk of gout flares. Monitor for hypersensitivity reactions, especially in renal impairment. Doses must be adjusted for renal function (Cr Cl <60 m L/min). Do not use with azathioprine or 6-mercaptopurine without dose reduction of cytotoxic agents. Avoid restarting after severe hypersensitivity.
Febuxostat is a non-purine selective xanthine oxidase inhibitor indicated for chronic management of hyperuricemia in gout. It is contraindicated with concomitant azathioprine, mercaptopurine, or theophylline due to risk of toxicity. Initiate at 40 mg daily; titrate to 80 mg if serum urate not at target after 2 weeks. Monitor for gout flares during initiation; provide prophylactic NSAIDs or colchicine for at least 6 months. Cardiovascular risk: increased risk of cardiovascular death vs allopurinol in patients with history of CV disease; avoid as first-line or in patients with prior MI or stroke. Assess liver function tests at baseline and periodically; discontinue if persistent elevation >3x ULN or signs of liver injury. Not recommended in patients with severe hepatic impairment (Child-Pugh C).
Take after meals to reduce GI upset.,Drink plenty of fluids (2-3 liters/day) to prevent kidney stones.,Report any rash, itching, or swelling immediately as these may signal a serious allergic reaction.,Do not stop medication abruptly; gout flares may occur during early treatment.,Avoid alcohol, especially beer, as it can increase uric acid levels.,Keep regular appointments for blood tests to monitor uric acid and kidney function.
Take exactly as prescribed; do not skip doses or stop without consulting your doctor.,You may experience gout flares during the first few months; continue your medication and take prescribed anti-inflammatory drugs as directed.,Report any signs of heart attack or stroke (chest pain, shortness of breath, weakness on one side of body, slurred speech) immediately.,Avoid alcohol, especially beer, which can increase uric acid levels and trigger gout flares.,Inform your doctor if you are taking azathioprine, mercaptopurine, or theophylline; these are not safe to take with febuxostat.,If you have a history of heart attack, stroke, or heart disease, discuss alternative treatments with your doctor.,Seek medical attention for signs of liver injury (yellow skin/eyes, dark urine, abdominal pain, persistent nausea).,Stay hydrated to help prevent kidney stones; aim for 8-10 glasses of water daily unless otherwise advised.,Do not crush or chew tablets; swallow whole with water.
"Concurrent use of bumetanide, a loop diuretic, and allopurinol, a xanthine oxidase inhibitor, may increase the risk of allopurinol hypersensitivity reactions, including Stevens-Johnson syndrome and acute gout flares. This interaction is thought to result from bumetanide-induced volume depletion and reduced renal clearance of oxypurinol, the active metabolite of allopurinol, leading to elevated serum oxypurinol levels and enhanced toxicity. Clinically, patients may present with rash, fever, eosinophilia, or acute gouty arthritis, particularly in those with renal impairment."
"The combination of allopurinol and captopril increases the risk of hypersensitivity reactions, including Stevens-Johnson syndrome and angioedema, due to a pharmacodynamic interaction that potentiates immune-mediated adverse effects. This is particularly concerning in patients with renal impairment, where both drugs may accumulate, and can lead to severe cutaneous adverse reactions or hematologic toxicities."
"Allopurinol inhibits xanthine oxidase, an enzyme involved in the catabolism of purine analogs. Tegafur is a prodrug of 5-fluorouracil and is metabolized via the same pathway. Coadministration of allopurinol may reduce the conversion of tegafur to its active metabolite, thereby decreasing the therapeutic efficacy of tegafur. This can lead to suboptimal antineoplastic effect and potential treatment failure."
"Mercaptopurine is metabolized by xanthine oxidase. Febuxostat inhibits xanthine oxidase, leading to significantly reduced clearance of mercaptopurine and its active metabolites. This can result in severe myelosuppression, including life-threatening neutropenia and thrombocytopenia, as well as hepatotoxicity."
"The serum concentration of the active metabolites of Aminophylline can be increased when Aminophylline is used in combination with Febuxostat."
"The serum concentration of Febuxostat can be increased when it is combined with Azathioprine."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about LOPURIN vs FEBUXOSTAT, answered by our medical review team.
LOPURIN is a Xanthine oxidase inhibitor that works by LOPURIN is a brand name for allopurinol, a xanthine oxidase inhibitor. It reduces uric acid production by inhibiting the conversion of hypoxanthine to xanthine and xanthine to uric acid.. FEBUXOSTAT is a Xanthine Oxidase Inhibitor that works by Febuxostat is a non-purine selective inhibitor of xanthine oxidase (XO). It inhibits both oxidized and reduced forms of XO, thereby reducing the conversion of hypoxanthine to xanthine and xanthine to uric acid, leading to decreased serum uric acid levels.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between LOPURIN and FEBUXOSTAT depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of LOPURIN is: 200-600 mg orally once daily, typically starting at 300 mg/day and adjusting based on serum urate levels.. The standard adult dose of FEBUXOSTAT is: 40 mg orally once daily; may increase to 80 mg orally once daily if serum urate goal not achieved after 2 weeks.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between LOPURIN and FEBUXOSTAT in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. LOPURIN is classified as Category C. FDA Pregnancy Category D. First trimester: risk of congenital heart defects, cleft palate, and hypospadias based on animal studies and limited human data. Second and third trimeste. FEBUXOSTAT is classified as Category C. Pregnancy Category C. No adequate studies in pregnant women. In animal studies, febuxostat caused developmental toxicity (reduced fetal weight, increased skeletal variations) at ma. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.