Study: Starting dose may be risk factor for AHS

Higher starting doses of allopurinol to treat gout may increase the risk for allopurinol hypersensitivity syndrome (AHS), according to a study published in the August 2012 issue of Arthritis & Rheumatism.

While dosing guidelines are based on the recognition that dosages of ≥300 mg/day may be associated with AHS, the relationship between the allopurinol starting dose and AHS was previously unknown, according to lead author Lisa K. Stamp with the University of Otago in Christchurch, New Zealand, and colleagues.

In the retrospective, case-control study of 54 patients with AHS and 157 controls, there was an increase in the risk of AHS as the starting dose of allopurinol corrected for the estimated glomerular filtration rate (GFR) increased. Of the AHS cases, 91%, and 36% of controls, received a starting dose of allopurinol of ≥1.5 mg/unit of estimated GFR.

“Our findings indicate that starting allopurinol at a dose of 1.5 mg/unit of estimated GFR may be associated with a reduced risk of AHS,” the researchers wrote. However, for patients who tolerate allopurinol, the dose can be gradually increased to achieve the target serum urate level, according to Stamp and colleagues.