1. Clinical Overview
Febuxostat is a potent, selective, non-purine xanthine oxidase inhibitor used for the long-term management of hyperuricemia in patients with gout. It is a first-line urate-lowering therapy (ULT) in India, particularly for patients intolerant to allopurinol or with renal impairment. It works by reducing serum uric acid (sUA) production.
| Onset | Duration | Bioavailability |
|---|---|---|
| Significant reduction in serum uric acid levels is typically observed within 2 weeks of initiation. | The pharmacological effect is sustained over 24 hours, allowing for once-daily dosing. | Approximately 49% (oral). High-fat meals can reduce the rate of absorption but do not significantly affect the extent. |
2. Mechanism of Action
Febuxostat is a potent, non-purine selective inhibitor of xanthine oxidase (XO), the enzyme responsible for the conversion of hypoxanthine to xanthine and xanthine to uric acid. By inhibiting XO, it reduces the production of uric acid, thereby lowering serum uric acid concentrations.
3. Indications & Uses
- Chronic management of hyperuricemia in patients with gout
4. Dosage & Administration
Adult Dosage: Recommended starting dose is 40mg once daily. May be increased to 80mg once daily if sUA is not below 6 mg/dL after 2 weeks with 40mg dose.
Administration: Administer orally, with or without food. Tablet should be swallowed whole with a glass of water. Maintain adequate hydration (at least 2 liters of fluid per day).
5. Side Effects
Common side effects may include:
- Liver function abnormalities (increased transaminases)
- Nausea
- Headache
- Rash
- Acute gout flares (especially during initiation)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Azathioprine | Increased levels of azathioprine leading to severe myelosuppression and pancytopenia. | Contraindicated |
| Mercaptopurine | Increased levels of mercaptopurine leading to severe myelosuppression and pancytopenia. | Contraindicated |
| Theophylline | Increased theophylline levels, risk of toxicity (nausea, seizures, arrhythmias). | Contraindicated |
| Didanosine | Potential increased risk of didanosine toxicity; avoid concomitant use. | Major |
| NSAIDs (e.g., Naproxen, Diclofenac) | Increased risk of NSAID-associated renal impairment; monitor renal function. | Moderate |
| Colchicine | No significant PK interaction, but commonly co-administered for gout flare prophylaxis. | Minor |
7. Patient Counselling
- DO take the tablet once daily as prescribed, with or without food.
- DO drink plenty of fluids (2-3 liters daily) to help prevent kidney stones.
- DO continue taking your prescribed gout flare prophylaxis medication (e.g., colchicine) as directed.
- DONT take this medicine if you are pregnant or planning pregnancy without consulting your doctor.
- DONT take this medicine if you are on azathioprine, mercaptopurine, or theophylline.
8. Toxicology & Storage
Overdose: Limited data. Potential symptoms may include nausea, vomiting, diarrhea, and elevated liver enzymes. Single doses up to 300mg have been administered without severe adverse effects.
Storage: Store at room temperature (15°C to 30°C). Protect from light and moisture. Keep in the original blister pack or container. Keep out of reach of children.