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) levels by inhibiting the enzyme responsible for uric acid 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). |
2. Mechanism of Action
Febuxostat is a non-purine selective inhibitor of xanthine oxidase (XO), the enzyme that catalyzes the oxidation of hypoxanthine to xanthine and xanthine to uric acid. By inhibiting XO, it decreases 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 40 mg once daily. For patients who do not achieve a serum uric acid level of less than 6 mg/dL after 2 weeks, the dose may be increased to 80 mg once daily.
Administration: Can be taken with or without food. Swallow the tablet whole with a glass of water. To be taken at the same time each day. Prophylaxis for gout flares with an NSAID or colchicine (0.5 mg once or twice daily) is recommended for up to 6 months.
5. Side Effects
Common side effects may include:
- Liver function abnormalities (increased transaminases)
- Nausea
- Arthralgia
- Rash
- Gout flare (especially during initiation)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Azathioprine | Febuxostat may increase plasma concentrations of azathioprine, leading to severe myelosuppression and toxicity. | Contraindicated |
| Mercaptopurine | Febuxostat may increase plasma concentrations of mercaptopurine, leading to severe myelosuppression and toxicity. | Contraindicated |
| Theophylline | Febuxostat may increase theophylline levels, increasing risk of toxicity (nausea, seizures, arrhythmias). | Contraindicated |
| Didanosine | Potential for increased toxicity; concomitant use not recommended. | Major |
| NSAIDs (e.g., Naproxen, Diclofenac) | Increased risk of hepatotoxicity; monitor LFTs. | Moderate |
| Colchicine | Used together for gout flare prophylaxis; monitor for colchicine toxicity (myopathy, neuropathy) especially in renal impairment. | Moderate |
| Warfarin | Potential for increased INR; monitor INR closely when initiating or discontinuing febuxostat. | Moderate |
7. Patient Counselling
- DO take the tablet once daily as prescribed, with or without food.
- DO continue taking your prescribed gout flare prevention medication (e.g., colchicine) as directed by your doctor, especially during the first 6 months.
- DO maintain adequate hydration by drinking plenty of fluids (2-3 liters per day unless contraindicated).
- DO NOT take the medicine if you are also taking azathioprine, mercaptopurine, or theophylline.
- DO NOT stop taking the medicine during a gout flare; continue it while treating the flare separately.
- DO NOT start the medication without informing your doctor about your complete medical history, especially heart, liver, or kidney problems.
8. Toxicology & Storage
Overdose: Limited data. Potential symptoms may include nausea, vomiting, diarrhea, and elevated liver enzymes. Doses up to 300 mg daily for 7 days have been tolerated in studies.
Storage: Store at room temperature (15-30°C), protected from light and moisture. Keep out of reach of children. Do not use after the expiry date printed on the pack.