Moderate
Allopurinol × Indapamide
Xanthine oxidase inhibitors×Thiazide-like diuretics
Mechanism
Indapamide (thiazide-like diuretic) raises allopurinol and oxypurinol levels, increasing hypersensitivity risk. The effect is weaker than with hydrochlorothiazide but clinically significant in older patients and chronic kidney disease.
Symptoms
Rash, fever, facial oedema, lymphadenopathy, abnormal liver function. Reactions develop 2–8 weeks after starting allopurinol.
Management
Dose allopurinol by creatinine clearance (start 100 mg/day if clearance below 60 mL/min). In Asian patients, HLA-B*58:01 testing is recommended. In significant hyperuricaemia, replacing indapamide with losartan lowers uric acid by 10–15%.