Safety, efficacy and renal effect of febuxostat in patients with moderate-to-severe kidney dysfunction

Efficacy of febuxostat on hyperuricemia and estimated glomerular filtration rate in patients with non-dialysis stage 3/4 chronic kidney disease and assessment of cardiac function: a 12-month interventional study

Objectives

Febuxostat, an oral medication for treating hyperuricemia (HUA), is a non-purine xanthine oxidase inhibitor that regulates serum uric acid (SUA) metabolism in patients with chronic kidney disease (CKD). However, the drug's effectiveness in improving renal function in patients with non-dialysis stage 3/4 CKD remains unclear. Our aim is to investigate the efficacy of febuxostat on kidney function. In addition, the cardiac function will be assessed.

Method

We conducted a single-center, interventional, randomized, controlled, open-label study. A total of 316 patients with non-dialysis stage 3/4 CKD, with SUA ≥6mg/dL in women and ≥7mg/dL in men, were assigned to either the febuxostat group (n=156) or the control group (n=160). The primary endpoint was the evaluation of changes in kidney biomarkers from baseline to 12 months of treatment, and any changes in cardiac biomarkers and echocardiographs were the secondary endpoint.

Results

The primary endpoint was a comparison between the two groups from baseline to 12 months of treatment. SUA was significantly decreased in patients treated with febuxostat 40 mg (6.85 ± 0.41mg/dL at baseline and 5.27 ± 0.70mg/dL at 12 months of treatment, P<0.001) and this was associated with increased eGFR (34.48 ± 8.42ml/min at baseline and 38.46 ± 8.87ml/min at 12 months of treatment, P<0.001). There were significant decreases in high-sensitivity troponin T (19.50 ± 7.24ng/L at baseline and 16.98 ± 7.32ng/L at 12 months of treatment, P<0.001) and N-terminal-pro brain natriuretic peptide (941.35 ± 374.30pg/ml at baseline and 762.22 ± 303.32 pg/ml at 12 months of treatment, P<0.001) in the febuxostat group. These changes were also associated with increased left ventricular ejection fraction in the febuxostat group (50.47 ± 3.95% at baseline and 51.12 ± 3.96% at the end of the study, P<0.001).

Conclusion

In the interventional group, febuxostat was well-tolerated and demonstrated a reduction in SUA associated with an increase in eGFR. This slowed down the progression of renal disease in patients with non-dialysis stage 3/4 CKD and improved cardiac function.

Comparative assessment of the effects of dotinurad and febuxostat on the renal function in chronic kidney disease patients with hyperuricemia

Although hyperuricemia is associated with chronic kidney disease (CKD), the impact of uric acid (UA)-lowering drugs on CKD has been controversial. Previous investigations have primarily included xanthine oxidase inhibitors; therefore, research of dotinurad, a recently developed selective urate reabsorption inhibitor, is necessary. This retrospective study included 58 patients with CKD; of these, 29 newly initiated dotinurad and 29 initiated febuxostat. The effects of dotinurad and febuxostat on the serum UA, urinary UA-to-creatinine ratio (UUCR), and estimated glomerular filtration rate (eGFR) during 3 months were analyzed to compare their impacts on renal function. Dotinurad and febuxostat decreased serum UA (8.40 ± 1.11 to 6.50 ± 0.80 mg/dL [p < 0.001] and 8.91 ± 1.21 to 6.05 ± 1.28 mg/dL [p = < 0.001], respectively). The UUCR increased after dotinurad (0.35 ± 0.15 to 0.40 ± 0.21 g/gCr [p = 0.024]); however, it decreased after febuxostat (0.33 ± 0.12 to 0.21 ± 0.06 g/gCr [p = 0.002]). The eGFR improved after dotinurad (33.9 ± 15.2 to 36.2 ± 15.9 mL/min/1.73 m2 [p < 0.001]). No change was observed after febuxostat treatment (33.4 ± 19.6 to 34.1 ± 21.6 mL/min/1.73 m2). Renal function improved only with dotinurad, thus highlighting its renoprotective effects beyond the reduction of serum UA.

Recent Progress and Future Perspectives on Anti-Hyperuricemic Agents

Increased biosynthesis or underexcretion of uric acid (UA or urate) in the body ultimately leads to the development of hyperuricemia. Epidemiological studies indicate that hyperuricemia is closely associated with the occurrence of various diseases such as gout and cardiovascular diseases. Currently, the first-line therapeutic medications used to reduce UA levels primarily include xanthine oxidase (XO) inhibitors, which limit UA production, and urate transporter 1 (URAT1) inhibitors, which decrease urate reabsorption and enhance urate excretion. Despite significant progress in urate-lowering therapies, long-term use of these drugs can cause hepatorenal toxicity as well as cardiovascular complications. Therefore, there is an urgent need for novel anti-hyperuricemic agents with better efficacy and lower toxicity. This perspective mainly focuses on the current research progress and design strategy of anti-hyperuricemic agents, particularly those targeting XO and URAT1. It is our hope that this perspective will provide insights into the challenges and opportunities for anti-hyperuricemic drug discovery.

A Possible Therapeutic Application of the Selective Inhibitor of Urate Transporter 1, Dotinurad, for Metabolic Syndrome, Chronic Kidney Disease, and Cardiovascular Disease

The reabsorption of uric acid (UA) is mainly mediated by urate transporter 1 (URAT1) and glucose transporter 9 (GLUT9) in the kidneys. Dotinurad inhibits URAT1 but does not inhibit other UA transporters, such as GLUT9, ATP-binding cassette transporter G2 (ABCG2), and organic anion transporter 1/3 (OAT1/3). We found that dotinurad ameliorated the metabolic parameters and renal function in hyperuricemic patients. We consider the significance of the highly selective inhibition of URAT1 by dotinurad for metabolic syndrome, chronic kidney disease (CKD), and cardiovascular disease (CVD). The selective inhibition of URAT1 by dotinurad increases urinary UA in the proximal tubules, and this un-reabsorbed UA may compete with urinary glucose for GLUT9, reducing glucose reabsorption. The inhibition by dotinurad of UA entry via URAT1 into the liver and adipose tissues increased energy expenditure and decreased lipid synthesis and inflammation in rats. Such effects may improve metabolic parameters. CKD patients accumulate uremic toxins, including indoxyl sulfate (IS), in the body. ABCG2 regulates the renal and intestinal excretion of IS, which strongly affects CKD. OAT1/3 inhibitors suppress IS uptake into the kidneys, thereby increasing plasma IS, which produces oxidative stress and induces vascular endothelial dysfunction in CKD patients. The highly selective inhibition of URAT1 by dotinurad may be beneficial for metabolic syndrome, CKD, and CVD.

Safety and Efficacy of Dotinurad on Uric Acid in Patients With Chronic Kidney Disease With Estimated Glomerular Filtration Rate Below 25 mL/Min/1.73 m²

Introduction Dotinurad is being developed as a selective uric acid reabsorption inhibitor. However, its effect on lowering serum uric acid (UA) levels in chronic kidney disease (CKD) patients with severe renal dysfunction is unknown. Therefore, the purpose of this study was to determine the effect of dotinurad on renal function in CKD patients with an estimated glomerular filtration rate (eGFR) below 25 mL/min/1.73 m2. Methods Seven patients with CKD who received dotinurad 0.5 mg to 4 mg per day were studied retrospectively. Changes in UA, eGFR, and urine protein-to-creatinine ratio (UPCR) were analyzed. The observation period was 10.9±2.1 months. Results Serum UA levels were decreased and maintained with dotinurad administration. Nevertheless, there were no improvements noted in renal function. Additionally, no serious adverse effects were identified in any of the patients throughout the observation period. Conclusion Although the sample size in this study was small, our findings demonstrate the efficacy of dotinurad in individuals with advanced CKD who have an eGFR lower than 25 mL/min/1.73 m2.

Effectiveness and safety of different doses of febuxostat compared with allopurinol in the treatment of hyperuricemia: a meta-analysis of randomized controlled trials

BACKGROUND

The prevalence of hyperuricemia has increased steadily with the continuous improvement of living standards. Some studies have reported the clinical effectiveness and safety of different doses of febuxostat in comparison with allopurinol in hyperuricemia treatment, but the sample sizes of the studies have been small, and the results have been inconsistent. We designed this meta-analysis to evaluate the effectiveness and safety of different doses of febuxostat compared with allopurinol in the treatment of hyperuricemia.

METHODS

The Cochrane Library, Embase, PubMed, Web of Science and ClinicalTrials.gov databases were searched to identify randomized controlled trials (RCTs) comparing the use of febuxostat and allopurinol for the treatment of hyperuricemia. The effectiveness and safety of different doses of febuxostat and allopurinol in treating hyperuricemia were assessed using meta-analysis.

RESULTS

A total of 11 randomized controlled trials were included in the meta-analysis. The results of the meta-analysis showed that the percentage of patients achieving serum uric acid levels of 6.0 mg/dL or less was higher among patients taking febuxostat (80 mg/d) than among patients taking allopurinol (200-300 mg/d) [RR = 1.79, 95% CI (1.55, 2.08), P < 0.00001]. However, there was no statistically significant difference in the percentage of patients achieving serum uric acid levels of 6.0 mg/dL or less between febuxostat (40 mg/d) and allopurinol (200-300 mg/d) [RR = 1.10, 95% CI (0.93, 1.31), P = 0.25]. There was also no statistically significant difference in the incidence of gout between the febuxostat (40 mg/d) and allopurinol (200-300 mg/d) [RR = 0.97, 95% CI (0.64, 1.49), P = 0.91] or between the febuxostat (80 mg/d) and allopurinol (200-300 mg/d) [RR = 1.13, 95% CI (0.81, 1.58), P = 0.48].No significant difference in the incidence of major adverse reactions as observed between the febuxostat (40 mg/d) and allopurinol (200-300 mg/d) [RR = 1.16; 95% CI (0.43, 3.16), P = 0.77] or between the febuxostat (80 mg/d) and allopurinol (200-300 mg/d) [RR = 1.06; 95% CI (0.79, 1.42), P = 0.70]. The incidence of adverse cardiovascular events did not differ significantly between the febuxostat (40 mg/d) and allopurinol (200-300 mg/d) [RR = 1.30; 95% CI (0.57, 2.95), P = 0.53] or between the febuxostat (80 mg/d) and allopurinol (200-300 mg/d) [RR = 1.79; 95% CI (0.74, 4.32), P = 0.20].

CONCLUSIONS

Febuxostat (80 mg/d) was associated with a higher percentage of patients achieving serum uric acid levels of 6.0 mg/dL or less than allopurinol (200-300 mg/d), however, febuxostat (80 mg/d) did not exhibit better efficacy in reducing the incidence of gout. More attention should be devoted to the adverse reactions caused by an increase in febuxostat doses.

The Efficacy and Safety of Dotinurad on Uric Acid and Renal Function in Patients with Hyperuricemia and Advanced Chronic Kidney Disease: A Single Center, Retrospective Analysis

Objective

We investigated the efficacy and safety of dotinurad, a selective urate reabsorption inhibitor, in hyperuricemic patients with advanced chronic kidney disease (CKD) (stage G3-5).

Patients and Methods

We retrospectively analyzed the cases of 34 patients (mean age, 68.6 ± 13.3 years; 17 men and 17 women) after 12 months of dotinurad treatment based on the changes in uric acid (UA) and the urine protein-to-creatinine ratio (UPCR) plus the annual change in estimated glomerular filtration rate (eGFR). Hyperuricemia (UA ≥6.0 mg/dL) and advanced CKD (mean eGFR: 32.0 ± 13.3 mL/min/1.73m2; stage G3, n=17; G4, n=13; G5, n=4) were present in all of the patients. The cases of 34 matched individuals with similar propensity scores (who were not taking dotinurad) were analyzed as a control group.

Results

UA values decreased significantly in the dotinurad group (7.1 ± 0.8 mg/dL to 5.9 ± 1.0 mg/dL, p<0.05) but those did not change in the control group. UPCR did not change in either group. Low-density lipoprotein cholesterol also decreased significantly in the dotinurad group (98.8 ± 43.4 mg/dL to 82.9 ± 33.1 mg/dL, p<0.05). With the 12-month dotinurad treatment, the annual change in the patients' eGFR was significantly improved from -6.0 ± 12.9 mL/min/1.73 m2/year to -0.9 ± 4.6 mL/min/1.73 m2/year (p<0.05), but there was no change in the control group.

Conclusion

Dotinurad can decrease UA levels and might attenuate renal function decline in individuals with hyperuricemia and advanced CKD.

Effects of febuxostat on markers of endothelial dysfunction and renal progression in patients with chronic kidney disease

Hyperuricemia relates to chronic kidney disease (CKD) progression and impaired endothelial function. Febuxostat is potent and effective for decreasing serum uric acid levels. Information for the effect of febuxostat treatment on markers of endothelial dysfunction and renal injury among patients with CKD remains limited. A total of 84 patients with CKD stages III-IV with asymptomatic hyperuricemia were randomly assigned to either the febuxostat (40 mg/day, N = 42) or the matching control (N = 42) group for 8 weeks. Serum asymmetric dimethylarginine (ADMA), estimated glomerular filtration rate (eGFR), urine albumin, high sensitivity C-reactive protein (hs-CRP), ankle brachial index (ABI) and serum uric acid were measured at baseline and at the end of study. Febuxostat administration significantly reduced the serum uric acid concentration among patients with CKD when compared with control [- 3.40 (95% CI - 4.19 to - 2.62) vs. - 0.35 (95% CI - 0.76 to 0.06) mg/dL; P < 0.001, respectively). No significant difference in the changes in serum ADMA, hs-CRP, eGFR and albuminuria was identified between the two groups. Subgroup analysis among patients with decreased serum uric acid after febuxostat, the estimated GFR change between the febuxostat and the control group showed significant difference at 8 weeks (2.01 (95% CI 0.31 to 3.7) vs. 0.04 (95% CI - 1.52 to 1.61) mL/min/1.73 m2; P = 0.030, respectively). Adverse events specific to febuxostat were not observed. Febuxostat effectively reduced serum uric acid in the CKD population without improving endothelial dysfunction. It was able to preserve renal function in the subgroup of patients with CKD and lower serum uric acid level after treatment.Trial registration: Thai Clinical Trials, TCTR20210224005: 24/022021 http://www.thaiclinicaltrials.org/show/TCTR20210224005 .

Effect of Febuxostat versus Allopurinol on the Glomerular Filtration Rate and Hyperuricemia in Patients with Chronic Kidney Disease

Hyperuricemia is a risk factor for the progression of chronic kidney disease (CKD). We compared febuxostat versus allopurinol in the progression of CKD and hyperuricemia in 101 patients with Stage 3-4 CKD treated with febuxostat or allopurinol for at least 6 months for hyperuricemia (>7 mg/dL) between January 2012 and December 2016. Baseline characteristics, serum uric acid (SUA), serum creatinine, and estimated glomerular filtration rate (eGFR) at entry and 6 months were compared. The primary outcome was the decline in eGFR and the secondary outcomes were reductions in SUA and adverse events. Fifty-four were in the febuxostat group and 47 were in the allopurinol group. The baseline characteristics were comparable except for age. The mean dose of febuxostat and allopurinol was 43.70 ± 14.5 mg and 108.51 ± 40 mg, respectively. After 6 months, the median rate of decline in eGFR was 1.2 mL/min/1.73 m2 (IQR: 1.2, 5.5) in the febuxostat group and 3.1 mL/min/1.73 m2 (0.6, 6.2) in the allopurinol group, but this was not statistically significant (P = 0.136). The mean reduction in SUA was significantly better (P = 0.004) in the febuxostat group (3.9 ± 1.7 mg/dL) compared with the allopurinol group (2.1 ± 1.0 mg/dL). Both drugs had no serious adverse events. Febuxostat was better at reducing hyperuricemia than allopurinol, but there was no significant difference in the progression of CKD. Large randomized trials and long-term follow-up are necessary to see whether febuxostat has a favorable effect on the progression of CKD.

The Hong Kong Society of Rheumatology consensus recommendations for the management of gout

Gout is one of the most common noncommunicable diseases in Hong Kong. Although effective treatment options are readily available, the management of gout in Hong Kong remains suboptimal. Like other countries, the treatment goal in Hong Kong usually focuses on relieving symptoms of gout but not treating the serum urate level to target. As a result, patients with gout continue to suffer from the debilitating arthritis, as well as the renal, metabolic, and cardiovascular complications associated with gout. The Hong Kong Society of Rheumatology spearheaded the development of these consensus recommendations through a Delphi exercise that involved rheumatologists, primary care physicians, and other specialists in Hong Kong. Recommendations on acute gout management, gout prophylaxis, treatment of hyperuricemia and its precautions, co-administration of non-gout medications with urate-lowering therapy, and lifestyle advice have been included. This paper serves as a reference guide to all healthcare providers who see patients who are at risk and are known to have this chronic but treatable condition.

Therapeutics in rheumatology and the kidney

The field of rheumatology has advanced significantly in recent years to provide rheumatologists with an extensive array of medications to combat rheumatic joint conditions. In contrast to an older era, when NSAIDs and other nephrotoxic agents were the mainstay of treatment, modern DMARDs vary considerably in their nephrotoxic potential and their use is not always precluded in populations with pre-existing chronic kidney disease (CKD). This review will explore in detail the safety and efficacy profiles of medications used to treat rheumatologic disease, specifically in the setting of CKD. Specifically, we discuss both traditional agents used, i.e. NSAIDs, CSs and conventional synthetic DMARDs, as well as novel biologic DMARDs and targeted synthetic DMARDs. Anti-gout prescribing in CKD is also reviewed. We aim to provide practical guidance to rheumatologists, nephrologists and general physicians when prescribing these medications in the setting of CKD.

Effects of febuxostat on delaying chronic kidney disease progression: a randomized trial in China

BACKGROUND

A few studies have tested febuxostat for its usefulness in delaying chronic kidney disease (CKD) progression by treating hyperuricemia and results were controversial. Thus, we attempted to conduct a randomized controlled study using the Chinese population with advanced grade of CKD.

METHODS

One hundred CKD patients in stages 3 and 4 with asymptomatic hyperuricemia from seven medical centers were included in this prospective randomized controlled study and assigned to the control and febuxostat group, the latter of which received febuxostat to titrate to achieve serum uric acid (SUA) < 6 mg/dL. The observation period was 12 months. The primary outcomes included the event of estimated glomerular filtration rate (eGFR) decline ≥ 30% or 50% from baseline at 12 months, dialysis and death from CKD; secondary outcome was the change in eGFR. Safety analysis was also performed.

RESULTS

Forty-seven patients and 45 patients in the febuxostat and control groups, respectively completed the study. Seven of 47 (14.9%) participants reached 30% decline in eGFR in the febuxostat group, while 1 (2.1%) and 2 (4.3%) patients reached 50% decline in eGFR or dialysis. Thirteen (28.9%), 10 (22.2%) and 3 (6.7%) of 45 patients reached primary kidney outcomes separately in the control group. The change in eGFR after 12 months from baseline in the febuxostat group was 0.50 mL/min/1.73 m², which was significantly higher than that in the control group - 4.46 mL/min/1.73 m² (p = 0.006). Adverse events did not differ between two groups.

CONCLUSIONS

Febuxostat effectively slowed eGFR decline in patients with CKD stages 3 and 4 and asymptomatic hyperuricemia.

Molecular Biological and Clinical Understanding of the Pathophysiology and Treatments of Hyperuricemia and Its Association with Metabolic Syndrome, Cardiovascular Diseases and Chronic Kidney Disease

Uric acid (UA) is synthesized mainly in the liver, intestines, and vascular endothelium as the end product of an exogenous purine from food and endogenously from damaged, dying, and dead cells. The kidney plays a dominant role in UA excretion, and the kidney excretes approximately 70% of daily produced UA; the remaining 30% of UA is excreted from the intestine. When UA production exceeds UA excretion, hyperuricemia occurs. Hyperuricemia is significantly associated with the development and severity of the metabolic syndrome. The increased urate transporter 1 (URAT1) and glucose transporter 9 (GLUT9) expression, and glycolytic disturbances due to insulin resistance may be associated with the development of hyperuricemia in metabolic syndrome. Hyperuricemia was previously thought to be simply the cause of gout and gouty arthritis. Further, the hyperuricemia observed in patients with renal diseases was considered to be caused by UA underexcretion due to renal failure, and was not considered as an aggressive treatment target. The evidences obtained by basic science suggests a pathogenic role of hyperuricemia in the development of chronic kidney disease (CKD) and cardiovascular diseases (CVD), by inducing inflammation, endothelial dysfunction, proliferation of vascular smooth muscle cells, and activation of the renin-angiotensin system. Further, clinical evidences suggest that hyperuricemia is associated with the development of CVD and CKD. Further, accumulated data suggested that the UA-lowering treatments slower the progression of such diseases.

Effectiveness of Drug Treatments for Lowering Uric Acid on Renal Function in Patients With Chronic Kidney Disease and Hyperuricemia: A Network Meta-Analysis of Randomized Controlled Trials

Background: Hyperuricemia is very common in patients with chronic kidney disease (CKD); the role of hyperuricemia in the occurrence and progression of kidney disease remains an interesting and unresolved issue for nephrologists, and whether urate-lowering therapy (ULT) is warranted in CKD patients is still in controversy. To summarize and compare the clinical outcomes and adverse events (AEs) of three common ULT drugs, we performed a systematic review and network meta-analysis of randomized clinical trials (RCTs). Method: PubMed, MEDLINE, Clinical Trials.gov, EMBASE, and the Cochrane Central Register of Controlled Trials electronic databases were searched. The network meta-analysis was performed using the "gemtc 0.8-7" and its dependent packages in R software. The primary outcome was the change of renal function and uric acid; creatinine, proteinuria, blood pressure, and adverse events were assessed as the secondary outcomes. Results: 16 RCTs involving 1,943 patients were included in the final network analysis. Febuxostat, allopurinol, and benzbromarone were not found to exert superior effects over placebo upon renoprotective effect. With respect to lowering urate, the three drugs showed to be statistically superior to placebo, while febuxostat could better lower urate than allopurinol (MD: -1.547; 95% CrI: -2.473 to -0.626). It is also indicated that febuxostat was superior to placebo at controlling blood pressure, while no differences were observed when allopurinol and benzbromarone were compared to placebo. These results are stable in subgroup analysis. Conclusion: There is insufficient evidence to support the renoprotective effects of the three urate-lowering agents in CKD patients with hyperuricemia; febuxostat shows a tendency to be superior to allopurinol on lowering the decline of eGFR and increment of proteinturia, but the difference does not reach a statistical significance. Regarding its urate-lowering effect, febuxostat appears to be a satisfactory alternative to allopurinol and benzbromarone, and can control blood pressure better.

[Asymptomatic Hyperuricemia: Treatment Approaches According to the Risk of Cardiovascular and Renal Events]

Asymptomatic hyperuricemia (HU) is widespread in the population. Results of multiple studies have demonstrated independent associations between increased levels of uric acid and risk of arterial hypertension, cardiovascular diseases, and chronic kidney disease. HU is considered as an independent predictor of cardiovascular and all-cause mortality. Despite the extensive study of this issue, there is still no unified answer to questions regarding the necessity of urate-lowering therapy in asymptomatic HU, whereas results of studies on the effect of this therapy on outcomes of cardiovascular and kidney diseases are controversial. This review summarized the basic, currently available information on this issue.

Comparative effect of allopurinol and febuxostat on long-term renal outcomes in patients with hyperuricemia and chronic kidney disease: a systematic review

Patients with chronic kidney disease (CKD) are more likely to develop hyperuricemia and gout. Allopurinol and febuxostat are the most commonly used urate-lowering therapies with established safety and efficacy in CKD patients. The objective of the systematic review is to assess the long-term renal outcomes of allopurinol compared with febuxostat in patients with hyperuricemia and CKD or kidney transplantation. PubMed MEDLINE, Embase, Web of Science, Scopus, and Cochrane CENTRAL databases were searched from inception to December 2019 using the key terms "allopurinol," "febuxostat," "xanthine oxidase inhibitors," "gout suppressants," "hyperuricemia," "gout," "chronic renal insufficiency," and "kidney transplantation." Studies with follow-up duration ≥ 12 months were included. Risk of bias was assessed using the Cochrane Risk Of Bias In Non-randomized Studies-of Interventions (ROBINS-I) tool. Three retrospective observational studies with follow-up duration ranging from 1 to 5 years were reviewed. Febuxostat patients had a significantly higher estimated glomerular filtration rate, reduced risk for renal disease progression, and reduced serum uric acid levels compared with allopurinol patients. All studies had a serious risk of bias. Febuxostat may be more renoprotective than allopurinol in patients with both hyperuricemia and CKD based on evidence from small long-term retrospective studies with serious risk of bias. More methodologically rigorous studies are needed to determine the clinical applicability of these results.

Renal effects of uric acid: hyperuricemia and hypouricemia

The prevalence of chronic kidney disease (CKD) is increasing worldwide. Although hyperuricemia has been associated with CKD in many studies, it remains controversial whether this is the cause or the result of decreased renal function. Recent observational studies of healthy populations and patients with CKD have reported that uric acid (UA) has an independent role in the development or progression of CKD. Experimental studies have shown several potential mechanisms by which hyperuricemia may cause or promote CKD. However, other reports have indicated an association between hypouricemia and CKD. This opposing effect is hypothesized to occur because UA is a major antioxidant in human plasma and is associated with oxidative stress. In this article, we discuss the potential association between UA imbalance and CKD and how they can be treated.

Febuxostat for Cerebral and CaRdiorenovascular Events PrEvEntion StuDy

Aims

To compare the occurrence of cerebral, cardiovascular, and renal events in patients with hyperuricaemia treated with febuxostat and those treated with conventional therapy with lifestyle modification.

Methods and results

This multicentre, prospective, randomized open-label, blinded endpoint study was done in 141 hospitals in Japan. A total of 1070 patients were included in the intention-to-treat population. Elderly patients with hyperuricaemia (serum uric acid >7.0 to ≤9.0 mg/dL) at risk for cerebral, cardiovascular, or renal disease, defined by the presence of hypertension, Type 2 diabetes, renal disease, or history of cerebral or cardiovascular disease, were randomized to febuxostat and non-febuxostat groups and were observed for 36 months. Cerebral, cardiovascular, and renal events and all deaths were defined as the primary composite event. The serum uric acid level at endpoint (withdrawal or completion of the study) in the febuxostat (n = 537) and non-febuxostat groups (n = 533) was 4.50 ± 1.52 and 6.76 ± 1.45 mg/dL, respectively (P < 0.001). The primary composite event rate was significantly lower in the febuxostat group than in non-febuxostat treatment [hazard ratio (HR) 0.750, 95% confidence interval (CI) 0.592–0.950; P = 0.017] and the most frequent event was renal impairment (febuxostat group: 16.2%, non-febuxostat group: 20.5%; HR 0.745, 95% CI 0.562–0.987; P = 0.041).

Conclusion

Febuxostat lowers uric acid and delays the progression of renal dysfunction.

Registration

ClinicalTrials.gov (NCT01984749).

Nitric Oxide-cGMP Signaling in Hypertension: Current and Future Options for Pharmacotherapy

For the treatment of systemic hypertension, pharmacological intervention in nitric oxide-cyclic guanosine monophosphate signaling is a well-explored but unexploited option. In this review, we present the identified drug targets, including oxidases, mitochondria, soluble guanylyl cyclase, phosphodiesterase 1 and 5, and protein kinase G, important compounds that modulate them, and the current status of (pre)clinical development. The mode of action of these compounds is discussed, and based upon this, the clinical opportunities. We conclude that drugs that directly target the enzymes of the nitric oxide-cyclic guanosine monophosphate cascade are currently the most promising compounds, but that none of these compounds is under investigation as a treatment option for systemic hypertension.

Recent approaches to gout drug discovery: an update

INTRODUCTION

Inflammation induced by urate deposition in joints causes gout. Healthy individuals maintain serum levels of urate by balancing urate production/excretion, whereas a production/excretion imbalance increases urate levels. Hyperuricemia is diagnosed when the serum urate level is continuously above 7 mg/dl as the solubility limit, and urate accumulates in the kidneys and joints. Because hyperuricemia increases the risk of gout, therapies aim to eliminate urate deposition to prevent gouty arthritis and kidney injury.

AREAS COVERED

This review discusses the mechanism underlying hyperuricemia with respect to urate production and urate transport, along with urate-lowering therapeutics, including urate synthesis inhibitors, uricolytic enzymes, and uricosuric agents. The authors asses published data on relevant commercial therapy development projects and clinical trials.

EXPERT OPINION

Available treatment options for hyperuricemia are limited. Allopurinol, a urate synthesis inhibitor, is generally administered at a reduced dosage to patients with renal impairment. Some URAT1 inhibitors have an unfavorable side effect profile. A promising strategy for treatment is the use of uricosuric agents that inhibit transporters (e.g. URAT1, URATv1/GLUT9, OAT10) which reabsorb urate from the urine.

Changeover Trial of Febuxostat and Topiroxostat for Hyperuricemia with Cardiovascular Disease: Sub-Analysis for Chronic Kidney Disease (TROFEO CKD Trial)

Background: The TROFEO trial demonstrated that febuxostat causes greater and more rapid reduction of serum uric acid (s-UA) than topiroxostat. We compared these drugs in patients with chronic kidney disease (CKD) by sub-analysis of the TROFEO trial.

Methods: This sub-analysis targeted patients with an estimated glomerular filtration rate (eGFR) ≤60 mL/min/1.73 m². The primary endpoint was the s-UA level. Secondary endpoints included creatinine, eGFR, urinary albumin, cystatin-C, oxidized low-density lipoprotein (Ox-LDL), eicosapentaenoic acid/arachidonic acid ratio, lipid biomarkers, high-sensitivity C-reactive protein, and B-type natriuretic peptide (BNP).

Results: There was no significant difference of s-UA between the two groups either before or after treatment. However, s-UA did not exceed 6.0 mg/dL in febuxostat group during the study period, but it exceeded this level in seven patients from topiroxostat group, with the number being significantly higher in topiroxostat group. Serum creatinine (s-Cr) and eGFR were significantly better after 6 months of febuxostat treatment compared with topiroxostat Cystatin-C was significantly lower after 6 months of febuxostat treatment compared with topiroxostat. The Ox-LDL was significantly lower after 3 and 6 months of febuxostat treatment compared with topiroxostat.

Conclusion: Febuxostat had stronger renoprotective and antioxidant effects than topiroxostat in patients with hyperuricemia and CKD.

Comparative effectiveness of allopurinol, febuxostat and benzbromarone on renal function in chronic kidney disease patients with hyperuricemia: a 13-year inception cohort study

Background

Direct comparisons of the effectiveness of allopurinol with that of other urate-lowering agents in chronic kidney disease (CKD) populations, as well as guideline recommendations for clinical practice, are lacking.

Methods

We constructed a pharmacoepidemiology cohort study by including patients from Taiwan's long-term integrated CKD care program to compare the effectiveness among allopurinol, febuxostat and benzbromarone in reducing the risk of progression to dialysis. A total of 874 patients with hyperuricemia who were newly treated with allopurinol, febuxostat or benzbromarone were included. The primary and secondary outcomes were incident end-stage renal disease (ESRD) and the serum uric acid (SUA) changes from baseline, respectively. The results were analyzed using multiple Cox proportional models adjusted for multinomial propensity scores. For subgroup analyses, we further stratified patients according to whether their latest SUA level reached the therapeutic target.

Results

Compared with allopurinol, benzbromarone therapy was associated with a reduced risk of progression to dialysis, the adjusted hazard ratio was 0.50 (95% confidence interval, 0.25-0.99). Patients who received allopurinol or febuxostat exhibited a comparable risk of ESRD [adjusted hazard ratio, 0.99 (0.40-2.44)]. Febuxostat was significantly more potent than allopurinol or benzbromarone in lowering SUA levels in the fully adjusted model. Among patients who reached the therapeutic target, those with febuxostat and benzbromarone initiation had a significantly lower risk of ESRD.

Conclusions

In conclusion, compared with conventional allopurinol, febuxostat and benzbromarone may be more effective in reducing the risk of progression to dialysis and in lowering SUA levels in CKD populations.

Gout

Gout is a chronic disease caused by monosodium urate (MSU) crystal deposition. Gout typically presents as an acute, self-limiting inflammatory monoarthritis that affects the joints of the lower limb. Elevated serum urate level (hyperuricaemia) is the major risk factor for MSU crystal deposition and development of gout. Although traditionally considered a disorder of purine metabolism, altered urate transport, both in the gut and the kidneys, has a key role in the pathogenesis of hyperuricaemia. Anti-inflammatory agents, such corticosteroids, NSAIDs and colchicine, are widely used for the treatment of gout flare; recognition of the importance of NLRP3 inflammasome activation and bioactive IL-1β release in initiation of the gout flare has led to the development of anti-IL-1β biological therapy for gout flares. Sustained reduction in serum urate levels using urate-lowering therapy is vital in the long-term management of gout, which aims to dissolve MSU crystals, suppress gout flares and resolve tophi. Allopurinol is the first-line urate-lowering therapy and should be started at a low dose, with gradual dose escalation. Low-dose anti-inflammatory therapies can reduce gout flares during initiation of urate-lowering therapy. Models of care, such as nurse-led strategies that focus on patient engagement and education, substantially improve clinical outcomes and now represent best practice for gout management.

Switching from allopurinol to febuxostat: efficacy and safety in the treatment of hyperuricemia in renal transplant recipients

The aim of this study was to evaluate the efficacy and tolerability of febuxostat in renal transplant recipients who were previously treated with allopurinol (the daily oral dose is 100 mg). A 6-month cohort study was conducted with 46 renal transplant recipients who had hyperuricemia. In 22 patients, treatment was changed from allopurinol to febuxostat (febuxostat was given at an oral dose of 20 mg once a day), and the other 24 patients continued the allopurinol treatment (the daily oral dose is 100 mg). The serum levels of uric acid (UA), creatinine, other biochemical parameters, estimated glomerular filtration rate (eGFR), and adverse events were measured at baseline as well as at 1, 3, and 6 months after the switch to febuxostat. Serum UA levels significantly decreased from 470.82 ± 34.37 to 378.77 ± 51.97 μmol/L in the febuxostat group, and decreased from 469.46 ± 33.47 to 428.21 ± 23.37 μmol/L in the allopurinol group. The eGFR increased from 75.55 to 85.23 mL/min in the febuxostat group, and decreased from 78.79 to 70.31 mL/min in the allopurinol group. In renal transplant recipients, febuxostat reduced the serum UA levels resulting in minor short-term improvement of renal function with no changes in the other biochemical parameters.

Effects of febuxostat on renal function in patients with chronic kidney disease: A systematic review and meta-analysis

BACKGROUND/OBJECTIVE

Hyperuricemia has been proven to be an independent risk factor for chronic kidney disease (CKD). However, the role of hyperuricemia in the progression of CKD remains unclear. Thus, we performed a systematic review and meta-analysis to evaluate the efficacy and safety of febuxostat, a first line urate-lowering agent, in CKD patients with hyperuricemia.

METHODS

We have systematically searched for randomized controlled trials assessing the efficacy and safety of febuxostat versus control in CKD patients with hyperuricemia through MEDLINE, PubMed, EMBASE, and Cochrane databases. All statistical analyses were conducted by using the statistical package Review Manager, version 5.3.5. Heterogeneity was assessed using the Cochrane Q and I tests and summary statistics were reported with 95% confidence interval. Two-tailed test was used for analysis and a P value of <.05 is considered statistically significant.

RESULTS

Eleven eligible trials with 1317 participants were included in the meta-analysis. A significant reduction in serum uric acid was found in the febuxostat treated group. Also, a significant higher eGFR was found in the febuxostat treated group among CKD stage 3 and 4 patients. No significant difference of major complication or death was identified between treatment and control groups.

CONCLUSIONS

The meta-analysis showed that other than its urate-lowering effect, febuxostat presented a reno-protective effect in CKD patients. More studies with larger sample sizes and higher quality are required to clarify the role of febuxostat use in the progression of CKD.

Pharmacological urate-lowering approaches in chronic kidney disease

Chronic kidney disease (CKD) has become a global public health issue and uric acid (UA) remains a major risk factor of CKD. As the main organ for the elimination of UA, kidney owned a group of urate transporters in tubular epithelium. Kidney disease hampered the UA excretion, and the accumulation of serum UA in return harmed the renal function. Commercially, there are three kinds of agents targeting at urate-lowering, xanthine oxidoreductase inhibitor which prevents the production of UA, uricosuric which increases the concentration of UA in urine thus decreasing serum UA level, and uricase which converts UA to allantoin resulting in the dramatic decrement of serum UA. Of note, in patients with CKD, administration of above-mentioned agents, alone or combined, needs special attention. New evidence is emerging for the efficacy of several urate-lowering drugs for the treatment of hyperuricemia in patients with CKD. Besides, loads of novel and promising drug candidates and phytochemicals are in the different phases of research and development. As of today, there is insufficient evidence to recommend the widespread use of UA-lowering therapy to prevent or slow down the progression of CKD. The review summarized the evidence and perspectives about the treatment of hyperuricemia with CKD for medicinal chemist and nephrologist.

The Xanthine Oxidase Inhibitor Febuxostat Suppresses the Progression of IgA Nephropathy, Possibly via Its Anti-Inflammatory and Anti-Fibrotic Effects in the gddY Mouse Model

Recent clinical studies have demonstrated the protective effect of xanthine oxidase (XO) inhibitors against chronic kidney diseases, although the underlying molecular mechanisms remain unclear. However, to date, neither clinical nor basic research has been carried out to elucidate the efficacy of XO inhibitor administration for IgA nephropathy. We thus investigated whether febuxostat, an XO inhibitor, exerts a protective effect against the development of IgA nephropathy, using gddY mice as an IgA nephropathy rodent model. Eight-week-old gddY mice were provided drinking water with (15 μg/mL) or without febuxostat for nine weeks and then subjected to experimentation. Elevated serum creatinine and degrees of glomerular sclerosis and fibrosis, judged by microscopic observations, were significantly milder in the febuxostat-treated than in the untreated gddY mice, while body weights and serum IgA concentrations did not differ between the two groups. In addition, elevated mRNA levels of inflammatory cytokines such as TNFα, MCP-1, IL-1β, and IL-6, collagen isoforms and chemokines in the gddY mouse kidneys were clearly normalized by the administration of febuxostat. These data suggest a protective effect of XO inhibitors against the development of IgA nephropathy, possibly via suppression of inflammation and its resultant fibrotic changes, without affecting the serum IgA concentration.

The impact of serum uric acid reduction on renal function and blood pressure in chronic kidney disease patients with hyperuricemia

BACKGROUND

Febuxostat is tolerable in chronic kidney disease (CKD) patients with hyperuricemia. However, the long-term effect of lowering uric acid with febuxostat on renal function and blood pressure has not been elucidated.

METHODS

This was a 2 years retrospective observational study. 86 CKD patients with hyperuricemia who continued with allopurinol (allopurinol group, n = 30), switched from allopurinol to febuxostat (switched group, n = 25), or were newly prescribed febuxostat (febuxostat group, n = 31) were included in this study. Serum uric acid, estimated glomerular filtration rate (eGFR), blood pressure, and urinary protein were analyzed. Moreover, the impact of serum uric acid reduction on renal function and blood pressure was assessed.

RESULTS

Serum uric acid in the switched and febuxostat groups was significantly reduced at 6 months (switched group; 8.49 ± 1.32-7.19 ± 1.14 mg/dL, p < 0.0001, febuxostat group; 9.43 ± 1.63-6.31 ± 0.90 mg/dL, p < 0.0001). In the allopurinol group, serum uric acid was increased (6.86 ± 0.87-7.10 ± 0.85 mg/dL, p = 0.0213). eGFR was significantly increased (35.2 ± 12.8-37.3 ± 13.9 mL/min/1.73 m2, p = 0.0232), while mean arterial pressure (93.1 ± 10.8-88.2 ± 9.5 mmHg, p = 0.0039) was significantly decreased at 6 months in the febuxostat group, resulting in the retention of eGFR for 2 years.

CONCLUSIONS

The impact of serum uric acid reduction might have beneficial effects on CKD progression and blood pressure. However, a large prospective study is needed to determine the long-term efficacy of febuxostat therapy in CKD patients with hyperuricemia.

The urate-lowering efficacy and safety of febuxostat versus allopurinol in Chinese patients with asymptomatic hyperuricemia and with chronic kidney disease stages 3-5

BACKGROUND

While the dose of allopurinol is limited in patients with chronic kidney disease (CKD), information is lacking concerning the efficacy, safety, and maintenance dose of febuxostat in Chinese patients with hyperuricemia and with CKD stages 3-5.

METHODS

A single center, prospective cohort study was conducted in patients with CKD stages 3-5 and with hyperuricemia who had not yet begun to undergo renal replacement therapy. We enrolled 208 patients who were newly treated with febuxostat (n = 112) or allopurinol (n = 96) in this study. The efficacy of febuxostat was determined by the proportion of patients with serum uric acid (sUA) < 360 µmol/L at the end of the study and changes of renal function.

RESULTS

The target of sUA < 360 µmol/L was reached by 96.4% of participants in the febuxostat group and 37.5% in the allopurinol group at 6 months. The eGFR in the febuxostat group showed an increase from 28.45 to 30.65 mL/min/1.73 m² at 6 months, while in the allopurinol group, the eGFR decreased from 28.06 to 24.39 mL/min/1.73 m². Linear regression analysis showed that the reduction in sUA was significantly associated with an increase in eGFR and decrease in proteinuria. We found that 83.0% of the patients could remain with sUA < 360 µmol/L at a maintenance dose of febuxostat 20 mg/day.

CONCLUSION

Febuxostat had superior urate-lowering efficacy to that of allopurinol in Chinese Han patients with hyperuricemia with CKD stages 3-5, and the reduction in sUA levels was associated with a slower progression of renal function.

Side Effects and Interactions of the Xanthine Oxidase Inhibitor Febuxostat

The paper addresses the safety of febuxostat and summarizes reports on side effects and interactions of febuxostat published by the cut-off date (last day of literature search) of 20 March 2018. Publications on side effects and the interactions of febuxostat were considered. Information concerning the occurrence of side effects and interactions in association with the treatment with febuxostat was collected and summarized in the review. The incidence of severe side effects was much less frequent than mild side effects (1.2–3.8% to 20.1–38.7%). The rate and range of febuxostat side effects are low at doses of up to 120 mg and only increase with a daily dose of over 120 mg. The publications reveal no age-dependent increase in side effects for febuxostat. In patients with impaired renal function, no increase in adverse events is described with a dose of up to 120 mg of febuxostat per day. Patients with impaired liver function had no elevated risk for severe side effects. A known allopurinol intolerance increases the risk of skin reactions during treatment with febuxostat by a factor of 3.6. No correlation between treatment with febuxostat and agranulocytosis has been confirmed. Possible interactions with very few medications (principally azathioprine) are known for febuxostat. Febuxostat is well tolerated and a modern and safe alternative to allopurinol therapy.

Efficacy of febuxostat in hyperuricemic patients with mild-to-moderate chronic kidney disease: a meta-analysis of randomized clinical trials: A PRISMA-compliant article

BACKGROUND

To investigate the efficacy of febuxostat in hyperuricemic patients with chronic kidney disease (CKD), relevant randomized clinical trials (RCTs) were analyzed.

METHODS

We used PubMed, Medline, ISI Web of Science, CBMdisc, and Cochrane Library databases to conduct a systematic literature research. A fixed-effects model was used to evaluate the standardized mean differences (SMDs) with 95% confidence intervals (CIs). We conducted subgroup analysis, sensitivity analysis, and analyzed publication bias, to comprehensively estimate the renoprotective effects of febuxostat in hyperuricemic patients with CKD.

RESULTS

Among 296 retrieved studies, 5 relevant RCTs were included in the meta-analysis. The result showed that serum estimated glomerular filtration rate (eGFR) was improved after febuxostat treatment in hyperuricemic patients with CKD, with an SMD (95% CI) of 0.24 [-0.17 to 0.43] and P = .67 (fixed-effects model). No heterogeneity was observed across studies (I  = 0% and P = .67). Subgroup analysis suggested that treatment-related reductions in serum eGFR levels were not related to drug doses, intervention times, or region.

CONCLUSIONS

The present meta-analysis suggests that febuxostat may slow the progression of mild-to-moderate CKD. Given the limited number of included studies, additional large sample-size RCTs are required to determine the long-term renoprotective effects of febuxostat in hyperuricemic patients with CKD.

Risk of Febuxostat-Associated Myopathy in Patients with CKD

BACKGROUND AND OBJECTIVES

Febuxostat, a nonpurine xanthine oxidase inhibitor, is widely used to treat hyperuricemia. Although febuxostat-associated rhabdomyolysis was reported in some patients with CKD, the association between CKD and febuxostat-associated myopathy remains uncertain.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Our retrospective cohort study included 1332 patients using febuxostat in Taipei Medical University-Wanfang Hospital from February of 2014 to January of 2016. The primary predictor was time-averaged eGFR as calculated by the equation proposed by the 2009 Chronic Kidney Disease Epidemiology Collaboration. The outcome was febuxostat-associated myopathy defined as elevated creatine kinase levels during febuxostat use that were not attributed to other muscular injuries.

RESULTS

The median duration of febuxostat use was 224 days (25th, 75th percentiles: 86, 441.5 days). Of 1332 study participants, 1222 (91.7%) had CKD; the median eGFR was 20.8 ml/min per 1.73 m2 (25th, 75th percentiles: 9.0, 35.4 ml/min per 1.73 m2). Forty-one of the participants had febuxostat-associated myopathy (3.2%). All patients with myopathy had CKD, and the incident rate was 0.013 (95% confidence interval, 0.01 to 0.02) events per 100 patient-days in patients with CKD. Of 41 patients with myopathy, 37 had myositis, and four had rhabdomyolysis. Myopathy resolved in 17 patients who withdrew from treatment and eight patients who continued febuxostat treatment. Among the evaluated predictors, multivariate analysis showed that only the lowest eGFR tertile was significantly associated with myopathy in febuxostat users. The odds ratio of the lowest eGFR tertile to the highest tertile was 4.21 (95% confidence interval, 1.7 to 10.43). This finding remained consistent among subgroups stratified by age, sex, diabetes status, coronary artery disease, and statin or fibrate use.

CONCLUSIONS

Patients with severely reduced eGFR had higher risk of myopathy with treatment of febuxostat. Regular monitoring of creatine kinase level is suggested for early detection of febuxostat-associated myopathy, particularly in patients with CKD.

Management of Gout and Hyperuricemia in CKD

Hyperuricemia and gout, the clinical manifestation of monosodium urate crystal deposition, are common in patients with chronic kidney disease (CKD). Although the presence of CKD poses additional challenges in gout management, effective urate lowering is possible for most patients with CKD. Initial doses of urate-lowering therapy are lower than in the non-CKD population, whereas incremental dose escalation is guided by regular monitoring of serum urate levels to reach the target level of <6mg/dL (or <5mg/dL for patients with tophi). Management of gout flares with presently available agents can be more challenging due to potential nephrotoxicity and/or contraindications in the setting of other common comorbid conditions. At present, asymptomatic hyperuricemia is not an indication for urate-lowering therapy, though emerging data may support a potential renoprotective effect.

Gout - a guide for the general and acute physicians

Gout is the most prevalent inflammatory arthritis and affects 2.5% of the general population in the UK. It is also the only arthritis that has the potential to be cured with safe, inexpensive and well tolerated urate-lowering treatments, which reduce serum uric acid by either inhibiting xanthine oxidase - eg allopurinol, febuxostat - or by increasing the renal excretion of uric acid. Of these, xanthine oxidase inhibitors are used first line and are effective in 'curing' gout in the vast majority of patients. Gout can be diagnosed on clinical grounds in those with typical podagra. However, in those with involvement of other joints, joint aspiration is recommended to demonstrate monosodium urate crystals and exclude other causes of acute arthritis, such as septic arthritis. However, a clinical diagnosis of gout can be made if joint aspiration is not feasible. This review summarises the current understanding of the pathophysiology, clinical presentation, investigations and treatment of gout.

Efficacy and safety of febuxostat in 73 gouty patients with stage 4/5 chronic kidney disease: A retrospective study of 10 centers

OBJECTIVES

The allopurinol dose is limited in chronic kidney disease, particularly stage 4/5 chronic kidney disease. Febuxostat has a hepatic metabolism and has been approved without dose adaptation in gouty patients with stage 1-3 chronic kidney disease. We aimed to study the safety and efficacy of febuxostat for stage 4/5 chronic kidney disease.

METHODS

In this retrospective study, we included patients with (1) a diagnosis of gout, (2) febuxostat treatment, (3) estimated glomerular filtration rate≤30mL/min/1.73m² (Modification of Diet in Renal Disease formula) at febuxostat initiation and (4) follow-up for at least 3 months after febuxostat initiation. Efficacy, safety and variation in estimated glomerular filtration rate were analyzed.

RESULTS

We included 73 patients (mean age 70.2±11.8, 61 men, 31 with vascular chronic kidney disease and 18 renal transplantation) with gout (baseline serum uric acid level=9.86±2.85mg/dL, mean gout duration 6.2±7.0 years) from 10 academic centers. Comorbidities included cardiac failure (17.8%), hypertension (98.6%), diabetes mellitus (30.1%), dyslipidemia (64.8%) and history of cardiovascular events (38.4%). At the last visit (mean follow-up 68.5±64.8 weeks), the daily dose of febuxostat was 40mg for 7 patients (10.5%), 80mg for 50 (74.6%) and 120mg for 10 (14.9%). Serum uric acid level was<6mg/dL for 49 patients (67%). Renal function improved for 18 patients, was unchanged for 24 and worsened for 31; 19 patients experienced flares and 1 patient, limb edema.

CONCLUSION

Febuxostat seemed efficient in gouty patients with stage 4/5 chronic kidney disease. However, safety data were not clear regarding renal function. Larger studies are needed to assess safety.

Hyperuricemia, the kidneys, and the spectrum of associated diseases: a narrative review

Hyperuricemia (elevated serum uric acid) is prevalent, and an important mediator of gout, an increasingly common condition. In addition, hyperuricemia is associated with metabolic syndrome, diabetes, hypertension, and kidney and cardiovascular diseases. Although it remains controversial whether hyperuricemia is a causal factor for kidney disease, the kidneys play a major role in the regulation of serum uric acid levels. Approximately two-thirds of the uric acid produced in humans is excreted by the kidneys. The handling of urate in the renal proximal tubule is extensive, as uric acid undergoes filtration, reabsorption, and secretion. Variations in renal urate handling have been shown to influence the risk of gout. In observational studies, hyperuricemia has been shown to predict kidney disease onset and progression, with a variety of mechanisms implicated. Because of this close association between hyperuricemia and kidney disease, and due to limited studies on the topic, it is important to conduct future studies on the treatment of hyperuricemia to slow kidney disease progression and improve cardiovascular survival in patients with chronic kidney disease. Furthermore, it is important to monitor for gout in patients with kidney disease and to follow the guidelines for treatment of hyperuricemia in this group of patients. This narrative review provides an in-depth discussion of the link between serum uric acid levels, renal handling of uric acid, and diseases associated with dysfunction in uric acid homeostasis.

Gout

Gout is a chronic disease of deposition of monosodium urate crystals, which form in the presence of increased urate concentrations. Although environmental factors contribute to hyperuricaemia, renal and gut excretion of urate is central to regulation of serum urate, and genetic factors are important. Activation of the NLRP3 inflammasome and release of interleukin 1β have key roles in initiation of acute gout flares. A "treat to target serum urate" approach is essential for effective gout management; long-term lowering of serum urate to less than 360 μmol/L leads to crystal dissolution and ultimately to suppression of flares. An allopurinol dose-escalation strategy is frequently effective for achieving treatment targets, and several new urate-lowering drugs are also available. Worldwide, rates of initiation and continuation of urate-lowering therapy are very low, and, consequently, achievement of serum urate targets is infrequent. Strategies to improve quality of gout care are needed.

Non-alcoholic fatty liver disease and dyslipidemia: An update

Non-alcoholic fatty liver (NAFLD) is the most common liver disease worldwide, progressing from simple steatosis to necroinflammation and fibrosis (leading to non-alcoholic steatohepatitis, NASH), and in some cases to cirrhosis and hepatocellular carcinoma. Inflammation, oxidative stress and insulin resistance are involved in NAFLD development and progression. NAFLD has been associated with several cardiovascular (CV) risk factors including obesity, dyslipidemia, hyperglycemia, hypertension and smoking. NAFLD is also characterized by atherogenic dyslipidemia, postprandial lipemia and high-density lipoprotein (HDL) dysfunction. Most importantly, NAFLD patients have an increased risk for both liver and CV disease (CVD) morbidity and mortality. In this narrative review, the associations between NAFLD, dyslipidemia and vascular disease in NAFLD patients are discussed. NAFLD treatment is also reviewed with a focus on lipid-lowering drugs. Finally, future perspectives in terms of both NAFLD diagnostic biomarkers and therapeutic targets are considered.

Time to target uric acid to retard CKD progression

Uric acid (UA) remains a possible risk factor of chronic kidney disease (CKD) but its potential role should be elucidated given a fact that multidisciplinary treatments assure a sole strategy to inhibit the progression to end-stage renal disease (ESRD). In clinical setting, most observational studies showed that elevation of serum uric acid (SUA) independently predicts the incidence and the development of CKD. The meta-analysis showed that SUA-lowering therapy with allopurinol may retard the progression of CKD but did not reach conclusive results due to small-sized studies. Larger scale, randomized placebo-controlled trials to assess SUA-lowering therapy are needed. Our recent analysis by propensity score methods has shown that the threshold of SUA should be less than 6.5 mg/dL to abrogate ESRD. In animal models an increase in SUA by the administration of oxonic acid, uricase inhibitor, or nephrectomy can induce glomerular hypertension, arteriolosclerosis including afferent arteriolopathy and tubulointerstitial fibrosis. The ever-growing discoveries of urate transporters prompt us to learn UA metabolism in the kidney and intestine. One example is that the intestinal ABCG2 may play a compensatory role at face of decreased renal clearance of UA in nephrectomized rats, the trigger of which is not a uremic toxin but SUA itself. This review will summarize the recent knowledge on the relationship between SUA and the kidney and try to draw a conclusion when and how to treat asymptomatic hyperuricemia accompanied by CKD. Finally we will address a future perspective on UA study including a Mendelian randomization approach.

Renoprotective effect of the xanthine oxidoreductase inhibitor topiroxostat on adenine-induced renal injury

The aim of the present study was to reveal the effect of a xanthine oxidoreductase (XOR) inhibitor, topiroxostat (Top), compared with another inhibitor, febuxostat (Feb), in an adenine-induced renal injury model. We used human liver-type fatty acid-binding protein (L-FABP) chromosomal transgenic mice, and urinary L-FABP, a biomarker of tubulointerstitial damage, was used to evaluate tubulointerstitial damage. Male transgenic mice ( n = 24) were fed a 0.2% (wt/wt) adenine-containing diet. Two weeks after the start of this diet, renal dysfunction was confirmed, and the mice were divided into the following four groups: the adenine group was given only the diet containing adenine, and the Feb, high-dose Top (Top-H), and low-dose Top (Top-L) groups were given diets containing Feb (3 mg/kg), Top-H (3 mg/kg), and Top-L (1 mg/kg) in addition to adenine for another 2 wk. After withdrawal of the adenine diet, each medication was continued for 2 wk. Serum creatinine levels, the degree of macrophage infiltration, tubulointerstitial damage, renal fibrosis, urinary 15-F2t-isoprostane levels, and renal XOR activity were significantly attenuated in the kidneys of the Feb, Top-L, and Top-H groups compared with the adenine group. Serum creatinine levels in the Top-L and Top-H groups as well as renal XOR in the Top-H group were significantly lower than those in the Feb group. Urinary excretion of L-FABP in both the Top-H and Top-L groups was significantly lower than in the adenine and Feb groups. In conclusion, Top attenuated renal damage in an adenine-induced renal injury model.