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Xanthinuria due to xanthine dehydrogenase (XDH) deficiency is a rare genetic disorder characterized by hypouricemia and the accumulation of xanthine in the urine. We have identified an Afghan girl whose xanthinuria could be classified as type I xanthinuria based on an allopurinol loading test. Three mutations were identified in the XDH gene, 141insG, C2729T (T910M) and C3886T (R1296W). Site-directed mutagenesis followed by expression analysis in Escherichia coli revealed that not only the frame shift mutation 141insG impairs XDH activity, but also the missense mutation C2729T, while C3886T resulted in major residual activity of about 50% of the wild type. In this report, a case of xanthinuria type I with mutations of XDH was identified and characterized by expression studies., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Background: Allopurinol has been widely used for treatment of hyperuricemia, however, it may be associated with various adverse effects. Febuxostat has been identified as a potentially safe and efficacious alternative., Objectives: A multicenter, open-label, parallel, between-group comparative study was conducted to investigate the effects of renal function on the pharmacokinetics, pharmacodynamics, and safety of febuxostat, a novel inhibitor of uric acid synthesis., Methods: Based on creatinine clearance (Ccr), 29 subjects were assigned to 3 groups: normal renal function (Ccr ≥ 80 mL/min), mild renal dysfunction (80 mL/min > Ccr ≥ 50 mL/min), or moderate renal dysfunction (50 mL/min > Ccr ≥ 30 mL/min). Febuxostat was repeatedly orally administered at a dose of 20 mg/d for 7 days., Results: Impaired renal function caused a slight increase in systemic exposure to unchanged febuxostat and its oxidative metabolites, but the exposure did not increase through repeated administration. Moreover, renal impairment did not markedly reduce the effects of febuxostat on plasma uric acid levels. There were no clinically significant adverse events even in patients with impaired renal function., Conclusions: Febuxostat is considered an inhibitor of uric acid synthesis that could be used in patients with mild to moderate renal impairment without dose adjustment.

Background: : Allopurinol has been widely used for treatment of hyperuricemia, however, it may be associated with various adverse effects. Febuxostat has been identified as a potentially safe and efficacious alternative., Objectives: : A multicenter study with randomized, placebo-controlled, double-blind, parallel-group comparison was carried out to evaluate the efficacy and safety of febuxostat in 103 patients with hyperuricemia (including patients with gout) in Japan., Methods: : Subjects were treated with febuxostat (20 or 40 mg/d) or a placebo for 8 weeks. The variables evaluated were the percentage of patients achieving serum uric acid levels 6.0 mg/dL or less and the percent change in serum uric acid levels after 8 weeks., Results: : The percentage of patients achieving serum uric acid levels 6.0 mg/dL or less after 8 weeks was 91.2% in the febuxostat 40-mg/d group, 45.7% in the 20-mg/d group, and 0.0% in the placebo group. The percent changes in serum uric acid levels after 8 weeks were -44.9% in the febuxostat 40-mg/d group, -28.9% in the 20-mg/d group, and -0.6% to -0.5% in the placebo group. No severe or medically significant adverse reaction attributable to febuxostat was noted, and there was no event that could pose a clinical problem. The efficacy did not differ depending on the presence/absence of gout history., Conclusions: : These results suggest that febuxostat (20 or 40 mg/d) is useful as a new means of treating hyperuricemia and is capable of reducing serum uric acid levels to 6.0 mg/dL or less (goal of treatment) with high safety regardless of the presence/absence of gout history.

Background: Allopurinol has been widely used for the treatment of hyperuricemia, however, it may be associated with various adverse effects. Febuxostat has been identified as a potentially safe and efficacious alternative., Objectives: Febuxostat was administered to patients with hyperuricemia including gout in Japan to compare its efficacy and safety with those of allopurinol., Methods: The starting dose of febuxostat and allopurinol was 10 and 100 mg/d, respectively, and was increased to the fixed maintenance dose of 40 or 60 mg/d for febuxostat and 300 mg/d for allopurinol for 16 weeks., Results: : The percent change in the serum uric acid level at 16 weeks compared with the baseline serum uric acid level was -42.96% ± 13.33% and -52.47% ± 9.79% for the febuxostat 40- and 60-mg/d groups, respectively, and -36.55% ± 18.59% for the allopurinol group, indicating that the hypouricemic effects of febuxostat increased in a dose-dependent manner and equaled to or surpassed those of allopurinol (P = 0.0239, 2-sample t test). The percentage of patients with serum uric acid levels of 6.0 mg/dL or less at 16 weeks was 88.9% and 100% for the febuxostat 40- and 60-mg/d groups, respectively, and 68.8% for the allopurinol group, showing higher achievements for the febuxostat groups compared with the allopurinol group. All adverse drug reactions were mild to moderate in severity, and there were no severe symptoms or reactions leading to drug discontinuation., Conclusions: These results suggest that febuxostat is safe at doses of 40 and 60 mg/d and has equal or greater efficacy than 300 mg/d allopurinol.

Background: Allopurinol has been widely used for the treatment of hyperuricemia, however, it may be associated with various adverse effects. Febuxostat has been identified as a potentially safe and efficacious alternative., Objectives: A multicenter study with randomized, placebo-controlled, double-blind, parallel, intergroup comparison was carried out to evaluate the dose-response relationship, efficacy, and safety of febuxostat in 202 patients with hyperuricemia (including patients with gout) in Japan., Methods: The subjects were treated with febuxostat at fixed maintenance doses (20-80 mg/d) or a placebo for 16 weeks. The percentage of patients achieving serum uric acid levels 6.0 mg/dL or less and the percent change in serum uric acid levels after 16 weeks of treatment were evaluated., Results: The percentage of patients achieving serum uric acid levels 6.0 mg/dL or less at 16 weeks was 87.8% in the 80-mg/d dose group, 83.3% in the 60-mg/d group, 82.9% in the 40-mg/d group, 46.5% in the 20-mg/d group, and 2.6% in the placebo group (P < 0.001, Mantel-Haenszel test). A statistically significant dose-response relationship was found. The percent change in serum uric acid levels after 16 weeks of treatment differed significantly between each febuxostat dose group and the placebo group and increased in a dose-dependent manner above 40 mg/d. No deaths, events posing a clinical problem, or serious adverse reactions attributable to febuxostat were noted. Similar results were obtained regardless of gout history., Conclusions: Febuxostat can safely reduce serum uric acid levels to 6.0 mg/dL or less in 80% or more of patients with hyperuricemia (including gout) at doses of 40 mg/d or higher.