What is allopurinol prescribed for?

From the Guidelines

Allopurinol is primarily prescribed to treat gout and high uric acid levels in the blood (hyperuricemia). It works by reducing the production of uric acid in the body by inhibiting the enzyme xanthine oxidase, which is responsible for converting purines into uric acid. According to the 2020 American College of Rheumatology guideline for the management of gout 1, allopurinol is the preferred first-line urate-lowering therapy (ULT) for patients with gout, including those with moderate-to-severe chronic kidney disease (CKD; stage >3).

The recommended dosing of allopurinol starts at a low dose (≤100 mg/day) and may be increased gradually to reach the target serum urate (SU) level of <6 mg/dl 1. The 2016 updated EULAR evidence-based recommendations for the management of gout also suggest starting allopurinol at a low dose (100 mg/day) and increasing by 100 mg increments every 2–4 weeks if required, to reach the uricaemic target 1.

Allopurinol is also used to prevent kidney stones in people with high uric acid levels and to manage tumor lysis syndrome, a condition that can occur during cancer treatment when many cancer cells die quickly, releasing their contents into the bloodstream. Common side effects include rash, stomach upset, and liver function abnormalities. Patients should take allopurinol with food to minimize stomach irritation and drink plenty of fluids to help prevent kidney stones. During initial treatment, patients may experience more gout attacks as uric acid crystals begin to dissolve, so colchicine or anti-inflammatory medications are often prescribed alongside allopurinol for the first few months of therapy.

Key points to consider when prescribing allopurinol include:

• Starting with a low dose and titrating upward to reach the target SU level
• Monitoring SU levels regularly to ensure the target is being met
• Adjusting the dose as needed to minimize side effects and maximize efficacy
• Considering concomitant anti-inflammatory prophylaxis therapy for at least 3–6 months when initiating ULT 1
• Maintaining a lifelong SU target of <6 mg/dl to prevent recurrence of gout flares 1

From the FDA Drug Label

Allopurinol tablets are indicated in:

1. the management of patients with signs and symptoms of primary or secondary gout (acute attacks, tophi, joint destruction, uric acid lithiasis, and/or nephropathy).
2. the management of patients with leukemia, lymphoma and malignancies who are receiving cancer therapy which causes elevations of serum and urinary uric acid levels
3. the management of patients with recurrent calcium oxalate calculi whose daily uric acid excretion exceeds 800 mg/day in male patients and 750 mg/day in female patients

Allopurinol is prescribed for:

• Gout management: to manage signs and symptoms of primary or secondary gout
• Cancer treatment: to manage patients with leukemia, lymphoma, and malignancies who are receiving cancer therapy that causes elevations of serum and urinary uric acid levels
• Recurrent calcium oxalate calculi: to manage patients with recurrent calcium oxalate calculi who have high daily uric acid excretion 2

From the Research

Allopurinol Prescription Uses

Allopurinol is prescribed for several conditions, including:

• Gout: a form of arthritis characterized by sudden, severe attacks of pain, swelling, redness, and tenderness in one or more joints, often occurring at the base of the big toe 3, 4, 5, 6
• Hyperuricaemia: a condition where there is an excess of uric acid in the blood, which can lead to gout and other health problems 4, 6
• Chronic gouty arthritis: a condition where gout attacks occur frequently and can lead to joint damage and disability 7
• Uric acid nephropathy: a condition where high levels of uric acid in the blood can cause kidney damage 6
• Uric acid urolithiasis: a condition where high levels of uric acid in the blood can cause kidney stones 6

Patient Considerations

When prescribing allopurinol, considerations should be made for:

• Renal function: allopurinol dose should be adjusted based on the patient's creatinine clearance and serum urate level, especially in patients with renal impairment 4
• Liver function: allopurinol should be used with caution in patients with liver disease, as it can cause liver damage 4
• Age: elderly patients may require lower doses of allopurinol due to decreased renal function and increased risk of side effects 4
• Concomitant medications: allopurinol can interact with other medications, such as diuretics, and increase the risk of side effects 4