Allopurinol Starting Dose Might Affect Risk for Hypersensitivity Reactions

Acute hypersensitivity reactions — often including rash, hepatotoxicity, and renal toxicity — are a rare but feared complication of allopurinol. To determine whether the starting dose of allopurinol is a risk factor for hypersensitivity, New Zealand researchers identified 54 cases of allopurinol hypersensitivity syndrome that occurred during a 12-year period in patients with gout. Each case patient was matched (by age, sex, diuretic use, and renal function) with three allopurinol-treated controls with gout who did not develop hypersensitivity. At baseline, estimated mean glomerular filtration rate (GFR) was about 50 mL/minute/1.73 m² in both cases and controls.

Median time from starting allopurinol to development of acute hypersensitivity wa…