Objectives: Gout patients with chronic kidney disease (CKD) accumulate the active allopurinol metabolite oxypurinol, suggesting that allopurinol may promote greater serum urate (sU) lowering in CKD patients.
Methods: We identified all patientswith gout diagnoses on either 100 mg or 300 mg of allopurinol daily, with available pre- and on-treatment sU levels, in our system in a 1-year period. Mean sU decrement by dosing per CKD groups was determined by CKD stage.
Results: Of 1,288 subjects with gout, 180 met entry criteria, with 83 subjects receiving 100 mg and 97 receiving 300 mg allopurinol. Subjects with CKD stage 1 experienced less sU lowering with 100 mg than 300 mg of allopurinol. Subjects with stage 4 and 5 CKD had equivalent sU decreases across the 100 mg and 300 mg allopurinol groups. However, the 100 mg group started at a higher pre-treatment sU and ended at a higher final sU than the 300 mg group.
Conclusions: The strategy of titrating allopurinol to sU in patients with kidney impairment may result in greater sU lowering at lower doses than in patients without CKD but may also pose a treatment challenge from a possible drug ceiling effect.