Abstract:Background: Irbesartan has been reported to inhibit renal uric acid reabsorption and thereby decrease serum uric acid (Sur) levels. However, its effect on uric acid metabolism in hypertensive patients has not been reported. Methods and Results: We conducted a retrospective observational study that included 40 hypertensive patients to clarify the effects of irbesartan (mean dose 87.5 mg) on blood pressure (BP) and uric acid metabolism [Sur, urinary uric acid (Uur), serum creatinine (Scr), urinary creatinine (Ucr), uric acid clearance (Cur), creatinine clearance (Ccr), urinary uric acid to urinary creatinine ratio (Uur/Ucr), and uric acid clearance to creatinine clearance ratio (Cur/Ccr)] at baseline and after 3 months of treatment. We allocated patients into two groups, patients with Uur/Ucr <0.5 (low Uur/Ucr group) or those with Uur/Ucr ! 0.5 (normal/ high Uur/Ucr group), into other two groups, patients with Cur/Ccr <5.5% (low Cur/Ccr group) or those with Cur/Ccr ! 5.5% (normal/ high Cur/Ccr group). The hypoexcretion group contained low Uur/Ucr group and low Cur/Ccr group, and the normal/ hyperexcretion group contained normal/high Uur/Ucr group and normal/ high Cur/Ccr group. Further, we allocated patients into another two groups, patients with Sur ! 7 mg/dl (hyperuricemic group) or those with Sur <7 mg/dl (normouricemic group). Irbesartan significantly decreased systolic BP without affecting heart rate, and decreased Sur without altering Uur/Ucr or Cur/Ccr. In the hypoexcretion group, irbesartan decreased Sur while increasing Uur/Ucr and Cur/Ccr. In contrast, in the normal/hyperexcretion and hyperuricemic groups, irbesartan decreased Sur without changing Uur/Ucr or Cur/ Ccr. In a normouricemic group, patients showed no changes in Sur after treatment with irbesartan. Conclusions: Irbesartan improved the secretion of uric acid, and reduced Sur in the hypoexcretion group, but did not influence uric acid excretion in the normal/hyperexcretion group. In hyperuricemic patients, irbesartan did not affect uric acid excretion but may have influenced uric acid production.