Milurit (Allopurinol)

Allopurinol is used to lower uric acid levels in conditions related to purine metabolism.

• Gout: reduces serum uric acid, decreasing frequency of acute attacks and tophi formation.
• Hyperuricemia: maintains target uric acid concentrations to prevent crystal deposition.
• Tumor lysis syndrome: prophylaxis by limiting rapid uric acid rise during chemotherapy.

• Allopurinol is a structural analogue of hypoxanthine that competitively inhibits the enzyme xanthine oxidase. By blocking this key step in purine catabolism, the conversion of hypoxanthine to xanthine and xanthine to uric acid is reduced, leading to decreased production of uric acid and lower serum urate concentrations.

Allopurinol may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Rash: mild skin eruption that may appear shortly after treatment initiation.
• Nausea: feeling of sickness often accompanied by loss of appetite.
• Vomiting: expulsion of stomach contents, usually transient.
• Diarrhea: loose stools that can lead to mild dehydration.
• Abdominal pain: discomfort or cramping in the stomach area.
• Elevated liver enzymes: mild increase in hepatic transaminases detected on lab tests.

Serious or Rare Side Effects

• Stevens‑Johnson syndrome: severe skin reaction with blistering and mucosal involvement.
• Toxic epidermal necrolysis: life‑threatening skin detachment requiring urgent care.
• Agranulocytosis: marked reduction in white blood cells increasing infection risk.
• Hepatic failure: significant liver dysfunction presenting with jaundice and coagulopathy.
• Hypersensitivity syndrome: systemic reaction with fever, rash, and organ involvement.
• Acute renal failure: sudden loss of kidney function, especially in high‑risk patients.

When prescribing Allopurinol, several safety considerations should be observed to minimize risk.

• Renal impairment: dose adjustment may be required and renal function should be monitored.
• Hepatic impairment: use cautiously and monitor liver enzymes regularly.
• Initiate therapy at low dose: start with a reduced dose to reduce risk of hypersensitivity.
• Monitor serum uric acid: adjust dose to achieve target urate levels.
• Known hypersensitivity: avoid in patients with previous severe reactions to allopurinol.
• Store at ambient temperature: keep in the original packaging, protect from moisture and direct sunlight.

Allopurinol can interact with several medicines, altering their effectiveness or safety profile.

Major Interactions (Avoid)

• Azathioprine: increased toxicity leading to bone marrow suppression.
• Mercaptopurine: heightened risk of myelosuppression.
• Warfarin: potentiation of anticoagulant effect, requiring INR monitoring.

Moderate Interactions (Monitor Closely)

• NSAIDs: may reduce renal clearance of allopurinol, necessitating dose review.
• Diuretics: can increase serum uric acid levels, potentially diminishing therapeutic benefit.