This review aims to critically present the available clinical evidence supporting the treatment of chronic hyperuricemia with xanthine oxidase inhibitors. For this reason, the studies published on uric acid (UA)-lowering drugs in the English language from 2000 to August 2019 have been carefully reviewed. The terms "serum uric acid," "xanthine oxidase," "allopurinol," "febuxostat," and "topiroxostat" were incorporated into an electronic search strategy, alone and in combinations, in both MEDLINE (National Library of Medicine, Bethesda, MD) and the Cochrane Register of Controlled Trials (The Cochrane Collaboration, Oxford, UK). Even if new urate-lowering drugs seem of particular efficacy for acute treatment of refractory hyperuricemia, their use is supported by relatively small clinical evidence. On the contrary, large long-term clinical trials have demonstrated that xanthine oxidase inhibitors (XOIs, namely, allopurinol and febuxostat) are effective, safe, and relatively well-tolerated in most of the patients. They have mainly been tested in the elderly, in patients affected by chronic diseases such as heart failure and cancer, and in patients taking a large number of drugs, confirming their safety profile. Recent data also show that they could exert some positive effects on vascular health, renal function, and glucose metabolism. Their cost is also low. In conclusion, XOIs remain the first choice of UA-lowering drug for chronic treatment.

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Clinical Effects of Xanthine Oxidase Inhibitors in Hyperuricemic Patients.

This article aims to critically review the evidence on the available therapeutic strategies for the treatment of hyperuricemia. For this reason, several papers were reviewed. Xanthine oxidase inhibitors are the safest and most effective uric acid lowering drugs for the management of chronic hyperuricemia, while the efficacy of uricosuric agents is strongly modulated by pharmacogenetics. Emergent drugs (lesinurad, peglotidase) were found to be more effective for the acute management of refractory hyperuricemia, but their use is supported by a relatively small number of clinical trials so that further well-designed clinical research is needed to deepen their efficacy and safety profile.

https://www.mdpi.com/1648-9144/57/1/58/pdf

Therapeutic Strategies for the Treatment of Chronic Hyperuricemia: An Evidence-Based Update

Management of hyperuricemia in asymptomatic patients: A critical appraisal

Xanthine oxidase (XO), which can catalyze the formation of xanthine or hypoxanthine to uric acid, is the most important target of gout. To explore the conformational changes for inhibitor binding, molecular dockings and molecular dynamics simulations were performed. Docking results indicated that three inhibitors had similar pose binding to XO. Molecular dynamics simulations showed that the binding of three inhibitors influenced the secondary structure changes in XO. After binding to the inhibitor, the peptide Phe798-Leu814 formed different degrees of unhelix, while for the peptide Glu1065-Ser1075, only a partial helix region was formed when allopurinol was bound. Through the protein structure analysis in the simulation process, we found that the distance between the active residues Arg880 and Thr1010 was reduced and the distance between Glu802 and Thr1010 was increased after the addition of inhibitors. The above simulation results showed the similarities and differences of the interaction between the three inhibitors binding to the protein. MM-PBSA calculations suggested that, among three inhibitors, allopurinol had the best binding effect with XO followed by daidzin and puerarin. This finding was consistent with previous experimental data. Our results can provide some useful clues for further gout treatment research.

Molecular Dockings and Molecular Dynamics Simulations Reveal the Potency of Different Inhibitors against Xanthine Oxidase.

The cardiovascular safety of febuxostat compared to allopurinol for the treatment of gout remains equivocal. Febuxostat had a better safety outcome compared with allopurinol. In this systematic review and meta-analysis, we searched MEDLINE and Embase for articles published between March 1, 2000 and April 4, 2021, without any language restrictions. We did a systematic review and meta-analysis of included clinical trials to evaluate the cardiovascular safety of febuxostat compared to allopurinol for treatment of chronic gout. Two reviewers independently selected studies, assessed study quality, and extracted data. Risk ratios were calculated with random effects and were reported with corresponding 95% confidence intervals (CI). From 240 potentially relevant citations, 224 papers were excluded; 16 studies were ultimately included in the analysis. Febuxostat had a better safety outcome compared with allopurinol，which was the composite of urgent coronary revascularization (OR: 0.84, 95% CI: 0.77-0.90, p < .0001) and stroke (OR: 0.87, 95% CI: 0.79-0.97, p = .009). However, that difference was not found in nonfatal myocardial infarction (OR: 0.99, 95% CI: 0.80-1.22, p = .91), cardiovascular related mortality (OR: 0.98, 95% CI: 0.69-1.38, p = .89) and all-cause mortality (OR: 0.93, 95% CI: 0.75-1.15, p = .52). No significant differences in cardiovascular related mortality and all-cause mortality were observed across any subgroup. This meta-analysis adds new evidence regarding the cardiovascular safety of febuxostat in patients. Initiation of febuxostat in patients was not associated with an increased risk of death or serious cardiovascular related adverse events compared with allopurinol.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/clc.23643

Cardiovascular safety of febuxostat compared to allopurinol for the treatment of gout: A systematic and meta-analysis.

Background and aims Systemic reviews and meta-analyses suggest hyperuricemia is a cardiovascular risk factor. The effects of xanthine oxidase inhibitors on cardiac outcomes remain unclear. We assessed the effects of febuxostat and allopurinol on mortality and adverse reactions in adult patients with hyperuricemia. Methods and results PubMed and EMBASE were searched to retrieve randomized controlled trials of febuxostat and allopurinol from January 2005 to July 2018. The meta-analysis consisted of 13 randomized controlled trials with a combined sample size of 13,539 patients. Febuxostat vs. allopurinol was not associated with an increased risk of cardiac-related mortality in the overall population (OR: 0.72, 95% CI: 0.24–2.13, P = 0.55). Regarding adverse skin reactions, the patients receiving febuxostat had significantly fewer adverse skin reactions than those receiving allopurinol treatment (OR: 0.50, 95% CI: 0.30–085, P = 0.01). Compared with allopurinol, febuxostat was associated with an improved safety outcome of cardiac-related mortality and adverse skin reactions (OR: 0.72, 95% CI: 0.55–0.96, P = 0.02). The net clinical outcome, composite of incident gout and the safety outcome, was not different significantly in the patients receiving febuxostat or allopurinol (OR: 1.04, 95% CI: 0.76–0.1.42, P = 0.79). In sensitivity analyses, a borderline significance was found in the patients randomized to febuxostat vs. allopurinol regarding cardiac-related mortality (OR: 1.29, 95% CI: 1.00–1.67, P = 0.05) after the CARES study was included. Conclusion Febuxostat vs. allopurinol was associated with the improved safety outcome and have comparable mortality and net clinical outcome in patients with hyperuricemia. Registration number PROSPERO(CRD42018091657).

The net clinical benefits of febuxostat versus allopurinol in patients with gout or asymptomatic hyperuricemia - A systematic review and meta-analysis.

Fu-Shun Hsu

Papers

The net clinical benefits of febuxostat versus allopurinol in patients with gout or asymptomatic hyperuricemia - A systematic review and meta-analysis.