Allopurinol Dosing and Serious Cutaneous Reactions

The American College of Rheumatology (ACR) recommends that allopurinol should be started at a dose of ≤100 mg daily, and at ≤50 mg daily in patients with low estimated glomerular filtration rate (eGFR), to minimize risk for adverse drug reactions — including Stevens-Johnson syndrome and toxic epidermal necrolysis (NEJM JW Gen Med Jul 1 2020 and Arthritis Rheumatol 2020; 72:879). In this study, researchers used databases in Ontario to assess whether initial allopurinol dosing correlated with risk for severe cutaneous reactions in 47,000 patients (age, >65) with eGFR <60 mL/minute/1.73 m².

Roughly equal numbers of patients started taking >100 mg and ≤100 mg of allopurinol daily; these two groups were compared using propensity scoring to adjust…