Febuxostat displays potent mixed-type inhibition of the activity of purified bovine milk XO, with Ki and Ki' values of 0.6 and 3.1 nM respectively. Febuxostat(TMX-67), a newly synthesized xanthine oxidase/xanthine dehydrogenase (XOD/XDH) inhibitor, has almost no effect on DNFB-sensitized mice.[1] At concentrations up to 100 muM, febuxostat has no significant effects on the activities of the following enzymes of purine and pyrimidine metabolism: guanine deaminase, hypoxanthine-guanine phosphoribosyltransferase, purine nucleoside phosphorylase, orotate phosphoribosyltransferase and orotidine-5'-monophosphate decarboxylase.[2]
In vivo
Febuxostat, at a daily dose of 80 mg or 120 mg, was more effective than allopurinol at the commonly used fixed daily dose of 300 mg in lowering serum urate.[3] Daily febuxostat doses in the range 10 mg to 120 mg resulted in proportional mean serum urate reductions ranging from 25% to 70% and in proportional increases in maximum febuxostat plasma concentrations and area under plasma concentration versus time curves.[4]