Febuxostat (TEI 6720) is a xanthine oxidase inhibitor.

XO:0.6 nM(Ki)

When compared to L-isomer of sugar alone, Febuxostat (5–6 mg/kg/day) in combination with L-isomer of sugar significantly lowered uric acid, blood pressure, insulin, and triglyceride levels in rats; the combination also reduced renal vasoconstriction, glomerular pressure, and afferent arteriole constriction. Febuxostat prevented hyperuricemia, improved proteinuria, and protected renal function in rats treated with 5/6 nephrectomy (5/6 Nx) + oxonic acid (OA) + Febuxostat (Fx), and it also prevented glomerular hypertension in 5/6 Nx + vehicle (V)/OA + Febuxostat (Fx) treated rats. Post-transverse aortic constriction (TAC), Febuxostat (5 mg/kg/day, administered forcefully for 8 days) attenuated TAC-induced left ventricular (LV) hypertrophy and dysfunction. It further attenuated the increase in nitrotyrosine (indicating reduced myocardial oxidative stress), p-mTOR(Ser2488), and p-Erk(Thr202/Tyr204), without affecting total mTOR or Erk levels. Based on evaluations of nitrotyrosine, urinary 8-isoprostane, and thiobarbituric acid reactive substances, Febuxostat significantly inhibited the activity of oxonic acid and reduced oxidative stress in the kidneys of Sprague-Dawley rats with unilateral right nephrectomy and left kidney ischemia/reperfusion (I/R) injury. Febuxostat also decreased endoplasmic reticulum stress induction in these rats, as reflected by the assessment of ATF4, GRP-78, and CHOP markers.

Febuxostat inhibits the activity of mixed-type purified bovine milk xanthine oxidase, with Ki and Ki' values of 0.6 nM and 3.1 nM, respectively, and is also effective against both reduced and oxidized forms of xanthine oxidase.