Generic Name: Allopurinol 100 mg & 300 mg
Therapeutic Class: Antigout (Xanthine Oxidase Inhibitor)
Indications
Allopurinol is indicated for reducing urate/uric acid formation in conditions where it has been deposited or is predicted to occur. Key indications include:
- Gout: Treatment of idiopathic gout (recurrent attacks).
- Urolithiasis: Prevention and treatment of uric acid and calcium oxalate renal stones.
- Hyperuricemia: Management of elevated uric acid levels associated with leukemia, lymphoma, and other malignancies or chemotherapy.
- Certain enzyme disorders (Lesch-Nyhan syndrome) leading to overproduction of urate.
Presentation
Tablet: Available as 100 mg and 300 mg tablets.
Description
Allopurinol is a xanthine-oxidase inhibitor. It and its main metabolite, oxypurinol, lower the level of uric acid in plasma and urine by inhibition of xanthine oxidase, the enzyme that catalyzes the oxidation of hypoxanthine to xanthine and xanthine to uric acid. By reducing uric acid production, it prevents the crystal deposits that cause gouty arthritis and kidney stones.
Dosage & Administration
Allopurinol should be taken **after a meal** to minimize gastrointestinal irritation.
- Adults: Initially 100 mg once daily. Maintenance dose is 100-300 mg daily for mild conditions and up to 700-900 mg for severe gout.
- Children (under 15 years): 10-20 mg/kg body weight daily (max 400 mg), primarily in cases of malignant disease.
- Renal Impairment: Dosage must be reduced in patients with severe renal insufficiency.
Side Effects
The most common side effect is skin rash. Other effects include gastrointestinal upset (nausea, vomiting), drowsiness, and headache. Rarely, a severe hypersensitivity syndrome (SJS/TEN) can occur. In the beginning of treatment, an increase in acute gouty attacks may be observed.
Pregnancy & Lactation
Pregnancy: Not recommended unless there is no safer alternative and the disease itself carries risk for the mother or child.
Lactation: Allopurinol is excreted in breast milk. Use with caution.
Lactation: Allopurinol is excreted in breast milk. Use with caution.
Precautions & Interactions
Precautions: Discontinue at the first sign of skin rash. Maintain high fluid intake (2 liters/day).
Interactions: Increases the effect of Azathioprine and 6-Mercaptopurine (reduce their dose to 25%). May interact with Warfarin and Thiazide diuretics.
Interactions: Increases the effect of Azathioprine and 6-Mercaptopurine (reduce their dose to 25%). May interact with Warfarin and Thiazide diuretics.
Storage
Store in a cool and dry place, below 30°C. Protect from light.
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