Comparison of the efficacy and safety of benzbromarone and febuxostat in gout and hyperuricemia: a systematic review and meta-analysis.

OBJECTIVE: Urate-lowering therapy (ULT) is widely recognized as the primary treatment for hyperuricemia and gout. Xanthine oxidase inhibitors (XOI), particularly febuxostat, have gained popularity as a frontline approach. However, the divergent efficacy and safety between febuxostat and the traditional ULT drug, benzbromarone, remain poorly understood. This knowledge gap necessitates a comprehensive analysis and evidence update to guide drug selection for physicians and patients. METHOD: We conducted a systematic analysis by extracting relevant clinical studies from four medical literature databases. Forest plots, funnel plots, sensitivity analysis, Egger's test, and subgroup analysis were utilized to compare relevant indicators. RESULTS: The advantages and disadvantages of the two drugs were evaluated based on various indicators such as serum uric acid (SUA), triglyceride (TG), urinary uric acid (UUA), white blood cell count (WBC), total cholesterol (TC), blood urea nitrogen (BUN), alanine aminotransferase (ALT), aspartate aminotransferase (AST), estimated glomerular filtration rate (eGFR), and serum creatinine (SC). Benzbromarone demonstrated better efficacy in rapidly reducing SUA levels and inhibiting inflammation for hyperuricemia and gout patients. Febuxostat was slightly less effective in lowering SUA, but there was no significant difference in its impact on liver and kidney function after long-term use. CONCLUSION: This study highlights the superiority of benzbromarone in rapidly reducing SUA and inhibiting inflammation. Febuxostat shows comparable effects on liver and kidney function after long-term use. These findings provide valuable insights for clinicians and patients in drug selection. Key Points • Benzbromarone stands out as a highly effective treatment for hyperuricemia and gout, offering rapid reduction of serum uric acid levels and potent anti-inflammatory effects. • When it comes to long-term use, febuxostat demonstrates comparable effects on liver and kidney function. This provides reassurance for patients who require extended treatment duration. • Moreover, our study goes beyond previous research by presenting a more comprehensive and detailed analysis.

A Benzarone Derivative Inhibits EYA to Suppress Tumor Growth in SHH Medulloblastoma.

Medulloblastoma is one of the most common malignant brain tumors of children, and 30% of medulloblastomas are driven by gain-of-function genetic lesions in the Sonic Hedgehog (SHH) signaling pathway. EYA1, a haloacid dehalogenase phosphatase and transcription factor, is critical for tumorigenesis and proliferation of SHH medulloblastoma (SHH-MB). Benzarone and benzbromarone have been identified as allosteric inhibitors of EYA proteins. Using benzarone as a point of departure, we developed a panel of 35 derivatives and tested them in SHH-MB. Among these compounds, DS-1-38 functioned as an EYA antagonist and opposed SHH signaling. DS-1-38 inhibited SHH-MB growth in vitro and in vivo, showed excellent brain penetrance, and increased the lifespan of genetically engineered mice predisposed to fatal SHH-MB. These data suggest that EYA inhibitors represent promising therapies for pediatric SHH-MB. SIGNIFICANCE: Development of a benzarone derivative that inhibits EYA1 and impedes the growth of SHH medulloblastoma provides an avenue for improving treatment of this malignant pediatric brain cancer.

Inhibition of mucus secretion by niclosamide and benzbromarone in airways and intestine.

The Ca2+ activated Cl- channel TMEM16A (anoctamin 1; ANO1) is expressed in secretory epithelial cells of airways and intestine. Previous studies provided evidence for a role of ANO1 in mucus secretion. In the present study we investigated the effects of the two ANO1-inhibitors niclosamide (Niclo) and benzbromarone (Benz) in vitro and in vivo in mouse models for cystic fibrosis (CF) and asthma. In human CF airway epithelial cells (CFBE), Ca2+ increase and activation of ANO1 by adenosine triphosphate (ATP) or ionomycin was strongly inhibited by 200 nM Niclo and 1 µM Benz. In asthmatic mice airway mucus secretion was inhibited by intratracheal instillation of Niclo or Benz. In homozygous F508del-cftr mice, intestinal mucus secretion and infiltration by CD45-positive cells was inhibited by intraperitoneal injection of Niclo (13 mg/kg/day for 7 days). In homozygous F508del-cftr rats intestinal mucus secretion was inhibited by oral application of Benz (5 mg/kg/day for 60 days). Taken together, well tolerated therapeutic concentrations of niclosamide and benzbromarone corresponding to plasma levels of treated patients, inhibit ANO1 and intracellular Ca2+ signals and may therefore be useful in inhibiting mucus hypersecretion and mucus obstruction in airways and intestine of patients suffering from asthma and CF, respectively.

Benzbromarone Induces Targeted Degradation of HSP47 Protein and Improves Hypertrophic Scar Formation.

Fibrotic diseases are characterized by the abnormal accumulation of collagen in the extracellular matrix, leading to the functional impairment of various organs. In the skin, excessive collagen deposition manifests as hypertrophic scars and keloids, placing a substantial burden on patients and the healthcare system worldwide. HSP47 is essential for proper collagen assembly and contributes to fibrosis. However, identifying clinically applicable HSP47 inhibitors has been a major pharmaceutical challenge. In this study, we identified benzbromarone (BBR) as an HSP47 inhibitor for hypertrophic scarring treatment. BBR inhibited collagen production and secretion in fibroblasts from patients with keloid by binding to HSP47 and inhibiting the interaction between HSP47 and collagen. Interestingly, BBR not only inhibits HSP47 but also acts as a molecular glue degrader that promotes its proteasome-dependent degradation. Through these molecular mechanisms, BBR effectively reduced hypertrophic scarring in mini pigs and rats with burns and/or excisional skin damage. Thus, these findings suggest that BBR can be used to clinically treat hypertrophic scars and, more generally, fibrotic diseases.

Urate-lowering drugs for chronic kidney disease with asymptomatic hyperuricemia and hypertension: a randomized trial.

INTRODUCTION: Xanthine oxidase (XO) inhibitors may slow down chronic kidney disease (CKD) progression. The comparative effectiveness of the different urate-lowering drugs is unknown. The aim of this study was to determine whether urate-lowering therapy with an XO inhibitor (febuxostat) and that with a uricosuric drug (benzbromarone) are comparable in slowing renal function decline in patients with CKD complicated with hypertension and hyperuricemia. METHODS: This study was an open-label randomized parallel-group clinical trial of 95 patients with stage G3 CKD in Japan. The patients had hypertension and hyperuricemia without a history of gout. They were randomized to receive febuxostat ( n  = 47; febuxostat group) or benzbromarone ( n  = 48; benzbromarone group) and titrated to reduce their serum urate level to <6.0 mg/dl. The primary end-point was change in estimated glomerular filtration rate (eGFR) from baseline to 52 weeks. The secondary end-points included changes in uric acid level, blood pressure, urinary albumin-to-creatinine ratio, and XO activity. RESULTS: Of the 95 patients, 88 (92.6%) completed the trial. There were no significant differences in change in eGFR (in ml/min/1.73 m 2 ) between the febuxostat [-0.23, 95% confidence interval (CI), -2.00 to 1.55] and benzbromarone (-2.18, 95% CI, -3.84 to -0.52) groups (difference, 1.95; 95% CI, -0.48 to 4.38; P  = 0.115) nor in the secondary end-points, except for XO activity. Febuxostat significantly reduced XO activity ( P  = 0.010). There were no significant differences in primary and secondary outcomes between the groups. A decrease in eGFR was significantly less in the febuxostat group than that of the benzbromarone group in the CKDG3a, but not in CKDG3b, in the subgroup analysis. There were no adverse effects specific to either drug. CONCLUSIONS: No significant differences were found in the effects of febuxostat and benzbromarone in renal function decline in stage G3 CKD complicated with hyperuricemia and hypertension.

Uric acid-lowering therapy with benzbromarone in hypertension with asymptomatic hyperuricemia: a randomized study focusing left ventricular diastolic function.

BACKGROUND: Both hypertension and hyperuricemia are closely associated with the morbidity and mortality of heart failure with preserved ejection fraction (HFpEF). However, there is limited evidence on the effect of uric acid-lowering therapy on left ventricular (LV) diastolic function in this population. In this randomized study, we prescribed benzbromarone, a uric acid-lowering drug, to those with hypertension and asymptomatic hyperuricemia to investigate its clinical benefits by evaluating LV diastolic function, incidence of HFpEF and hospitalization for heart failure and cardiovascular death. METHODS: 230 participants were randomly assigned into two groups: uric acid-lowering group (benzbromarone) and control groups (without uric acid-lowering drug). The primary endpoint was LV diastolic function evaluated by echocardiography. The secondary endpoint of composite endpoints is the combination of new-onset HFpEF, hospitalization for heart failure and cardiovascular death. RESULTS: After a median of 23.5 months' follow-up (16-30 months), the primary endpoint reflected by E/e' in benzbromarone group reached a significant improvement when compared to control group (p <.001). Composite endpoints occurred in 11 patients of the control group while only 3 patients occurred in the benzbromarone group (p = .027). We also presented the favorable trend of freedom from the composite endpoints or new-onset HFpEF using Kaplan-Meier curve by log-rank test in benzbromarone group (p = .037 and p = .054). CONCLUSIONS: Our study demonstrated the efficiency of benzbromarone in hypertensive patients with concomitant asymptomatic hyperuricemia, including the benefits on ameliorating LV diastolic dysfunction as well as improving composite endpoints.

Comparison of benzbromarone and allopurinol on the risk of chronic kidney disease in people with asymptomatic hyperuricemia.

OBJECTIVE: The objective of the study was to compare the relative effects of benzbromarone and allopurinol on the risk of developing chronic kidney disease in persons with asymptomatic hyperuricemia. METHODS: A retrospective cohort study was conducted to analyze a 2003-2015 national database including all claims data of 2 million beneficiaries in Taiwan. Asymptomatic hyperuricemia was defined as follows: persons using urate-lowering drugs who never developed gout flares. The benzbromarone group included persons ages 20-84 that had asymptomatic hyperuricemia and received benzbromarone alone. The allopurinol group included persons ages 20-84 that had asymptomatic hyperuricemia and received allopurinol alone. The maximum follow-up time was set as 5 years in this study. The main outcome was defined as follows: persons were newly diagnosed with chronic kidney disease. A Cox proportional hazards regression analysis was performed to test the association between variables and the risk of chronic kidney disease. RESULTS: After propensity score matching, 9107 persons in the benzbromarone group and 4554 persons in the allopurinol group were eligible for the study. Approximately 71% of the study subjects were males. The mean age was 56 years old. The incidence rate of chronic kidney disease was lower in the benzbromarone group than in the allopurinol group (1.18 versus 1.99/per 100 person-years, incidence ratio = 0.60, and 95% confidence interval = 0.52-0.68).The Cox proportional hazards regression analysis disclosed that after adjusting for co-variables, there was a decreased risk of developing chronic kidney disease in the benzbromarone group as compared with the allopurinol group (hazard ratio = 0.59, 95% confidence interval = 0.52-0.67 and P<0.001). CONCLUSIONS: The use of benzbromarone is associated with a lower hazard of developing chronic kidney disease as compared to allopurinol use among persons ages 20-84 with asymptomatic hyperuricemia. More studies are needed to confirm our findings.

The TMEM16A blockers benzbromarone and MONNA cause intracellular Ca2+-release in mouse bronchial smooth muscle cells.

We investigated effects of TMEM16A blockers benzbromarone, MONNA, CaCCinhA01 and Ani9 on isometric contractions in mouse bronchial rings and on intracellular calcium in isolated bronchial myocytes. Separate concentrations of carbachol (0.1-10 µM) were applied for 10 min periods to bronchial rings, producing concentration-dependent contractions that were well maintained throughout each application period. Benzbromarone (1 µM) markedly reduced the contractions with a more pronounced effect on their sustained component (at 10 min) compared to their initial component (at 2 min). Iberiotoxin (0.3 µM) enhanced the contractions, but they were still blocked by benzbromarone. MONNA (3 µM) and CaCCinhA01 (10 µM) had similar effects to benzbromarone, but were less potent. In contrast, Ani9 (10 µM) had no effect on carbachol-induced contractions. Confocal imaging revealed that benzbromarone (0.3 µM), MONNA (1 µM) and CaCCinhA01 (10 µM) increased intracellular calcium in isolated myocytes loaded with Fluo-4AM. In contrast, Ani9 (10 µM) had no effect on intracellular calcium. Benzbromarone and MONNA also increased calcium in calcium-free extracellular solution, but failed to do so when intracellular stores were discharged with caffeine (10 mM). Caffeine was unable to cause further discharge of the store when applied in the presence of benzbromarone. Ryanodine (100 µM) blocked the ability of benzbromarone (0.3 µM) to increase calcium, while tetracaine (100 µM) reversibly reduced the rise in calcium induced by benzbromarone. We conclude that benzbromarone and MONNA caused intracellular calcium release, probably by opening ryanodine receptors. Their ability to block carbachol contractions was likely due to this off-target effect.

Effects of different doses glimepiride intake on the pharmacokinetics of benzbromarone in rats.

Benzbromarone (BNR) is prescribed for the management of hyperuricemia, whereas glimepiride (GLM) for the treatment of Type 2 Diabetes Mellitus. Both drugs are certified to be mainly metabolized via cytochrome P450 (CYP) 2C9 in vivo and may have the potential drug-drug interactions. This study aims to investigate the possible influence of orally administered low- and high-dose glimepiride (GLM) on pharmacokinetic characteristics (PK) of benzbromarone (BNR) in rats. Fifteen rats were randomly assigned to group A, B and C (n=5) and administered 0.5% sodium carboxymethyl cellulose (CMC), 0.5mg/kg GLM (low-dose) and 1.0 mg/kg GLM (high-dose) once daily for 8 days, respectively, which were all followed with a single oral dose of BNR (9.0 mg/kg) on the day 8th. Blood samples were obtained from retro orbital plexus at the time points of 0.25, 0.5, 1, 2, 4, 6, 8, 10, 12 and 24h and BNR in plasma was quantitated by HPLC-MS/MS assay. Resultantly a slight influence of GLM on PK of BNR could be found in rats. When compared with Group A, the half-life time (t1/2z) of BNR in Group B and C significantly decreased 52.39% and 73.49%, respectively, although other major PK parameters were negligibly changed by co-administration of GLM. On the whole, the combinational therapy of GLM at low or high dose would notably alter the elimination of BNR and the effect was dose-dependent.

Uricosuric Agents Affect Plasma and Kidney Concentration of Adefovir via Inhibition of Oat1 and Mrp2 in Rats.

Uricosuric agents lower serum uric acid levels by increasing urinary excretion via inhibition of urate transporter 1 (URAT1), urate reabsorption transporter in the renal proximal tubules. Probenecid and benzbromarone have been used as uricosurics, but these drugs inhibit organic anion transporters (OATs) in addition to URAT1. In this study, we investigated whether uricosuric agents interacted with adefovir, known as a substrate for OAT1, using Sprague-Dawley (SD) rats. Furthermore, involvement of other transporters, multi-drug resistance protein 2 (MRP2) in this interaction was examined using Mrp2-deficient rats. Probenecid and lesinurad increased plasma adefovir concentrations and decreased kidney-to-plasma partition coefficient (Kp) in these rats, presumably by inhibiting Oat1. Although benzbromarone had no effect on plasma adefovir concentration, it increased the Kp to 141% in SD rats. Since this effect was abolished in Mrp2-deficient rats, together with the MRP2 inhibition study, it is suggested that benzbromarone inhibits Mrp2-mediated adefovir excretion from the kidney. In contrast, dotinurad, a novel uricosuric agent that selectively inhibits URAT1, had no effect on the plasma and kidney concentrations of adefovir. Therefore, due to the lack of interaction with adefovir, dotinurad is expected to have low drug-drug interaction risk mediated by OAT1, and also by MRP2.

The risk of ischemic cerebrovascular disease associated with benzbromarone use in gout people: A retrospective cohort study in Taiwan.

Epidemiological studies have shown that people having hyperuricemia are at increased risk of ischemic cerebrovascular disease. This research aimed to study the relation of ischemic cerebrovascular disease with benzbromarone use among persons with gout-related disorders. This was a retrospective cohort design utilizing a 2003 to 2015 national health insurance database in Taiwan. Subjects aged 20 to 99 years who already had suffered from gout-related disorders were included as eligible subjects. Eligible persons who had the benzbromarone prescription alone were selected into the benzbromarone group. Sex-matched and age-matched eligible persons who never used any urate-lowering agents were selected into the control group. An index date was set as a date of benzbromarone being prescribed. The end-point was defined as ischemic cerebrovascular disease being newly diagnosed. A hazard ratio was applied to measure the association strength between benzbromarone use and ischemic cerebrovascular disease. Totally, there were 13,398 persons in the benzbromarone group and 13,398 persons in the control group. The incidence rate of ischemic cerebrovascular disease seemed to be modestly higher in the benzbromarone group than the control group, but it did not achieve statistical significance (0.78 vs 0.75 every 100 person-years, incidence rate ratio = 1.05, 95% confidence interval = 0.94-1.16). A crude hazard ratio of ischemic cerebrovascular disease showed 1.05 in the benzbromarone group (95% confidence interval = 0.94-1.17, P = .373) comparing with the control group. No significant association can be detected between benzbromarone use and the probability of ischemic cerebrovascular disease among persons with gout-related disorders. We think that reduction of the serum uric acid by use of benzbromarone could not be related to the probability of ischemic cerebrovascular disease. Further research is suggested to clarify this issue.

A Novel Role of Uricosuric Agent Benzbromarone in BK Channel Activation and Reduction of Airway Smooth Muscle Contraction.

The uricosuric drug benzbromarone, widely used for treatment of gout, hyperpolarizes the membrane potential of airway smooth muscle cells, but how it works remains unknown. Here we show a novel role of benzbromarone in activation of large conductance calcium-activated K+ channels. Benzbromarone results in dose-dependent activation of macroscopic big potassium (BK) currents about 1.7- to 14.5-fold with an EC50 of 111 µM and shifts the voltage-dependent channel activation to a more hyperpolarizing direction about 10 to 54 mV in whole-cell patch clamp recordings. In single-channel recordings, benzbromarone decreases single BKα channel closed dwell time and increases the channel open probability. Coexpressing ß1 subunit also enhances BK activation by benzbromarone with an EC50 of 67 µM and a leftward shift of conductance-voltage (G-V) curve about 44 to 138 mV. Site-directed mutagenesis reveals that a motif of three amino acids 329RKK331 in the cytoplasmic linker between S6 and C-terminal regulator of potassium conductance (RCK) gating ring mediates the pharmacological activation of BK channels by benzbromarone. Further ex vivo assay shows that benzbromarone causes reduction of tracheal strip contraction. Taken together, our findings demonstrate that uricosuric benzbromarone activates BK channels through molecular mechanism of action involving the channel RKK motif of S6-RCK linker. Pharmacological activation of BK channel by benzbromarone causes reduction of tracheal strip contraction, holding a repurposing potential for asthma and pulmonary arterial hypertension or BK channelopathies. SIGNIFICANCE STATEMENT: We describe a novel role of uricosuric agent benzbromarone in big potassium (BK) channel activation and relaxation of airway smooth muscle contraction. In this study, we find that benzbromarone is an activator of the large-conductance Ca2+- and voltage-activated K+ channel (BK channel), which serves numerous cellular functions, including control of smooth muscle contraction. Pharmacological activation of BK channel by the FDA-approved drug benzbromarone may hold repurposing potential for treatment of asthma and pulmonary arterial hypertension or BK channelopathies.

Cardiovascular risk of urate-lowering drugs: A study using the National Database of Health Insurance Claims and Specific Health Checkups of Japan.

In the present study, we aimed to investigate the association between urate-lowering drugs and cardiovascular events, primarily focusing on the risk of febuxostat and topiroxostat when compared with allopurinol in Japan. We conducted an observational study with a cohort design using the National Database of Health Insurance Claims and Specific Health Checkups of Japan, including new urate-lowering drugs users between August 1, 2010, and March 31, 2018. Exposure and control groups were defined based on the first prescription of urate-lowering drugs as follows: febuxostat or topiroxostat for exposure groups, allopurinol for the control group, and benzbromarone for the secondary control group. The primary outcome was cardiovascular events, defined as a composite of acute coronary syndrome, cerebral infarction, and cerebral hemorrhage. Hazard ratios were estimated using a Cox proportional hazards model. The number of patients in each exposure and control group was 1,357,671 in the febuxostat group, 83,683 in the topiroxostat group, 1,273,211 in the allopurinol group, and 258,786 in the benzbromarone group. The adjusted hazard ratios for the cardiovascular risk were 0.97 (95% confidence interval [CI]: 0.95-0.98) for febuxostat and 0.84 (95% CI: 0.78-0.90) for topiroxostat groups. The benzbromarone group exhibited similar results. No increased cardiovascular risk was observed with febuxostat or topiroxostat when compared with allopurinol in patients with hyperuricemia in Japan. These results provide real-world evidence regarding the cardiovascular risk associated with urate-lowering drugs, indicating that no additional safety-related regulatory actions are warranted in Japan.

Comparison of the efficacy of febuxostat vs. benzbromarone in the treatment of gout: a meta-analysis in Chinese gout patients.

OBJECTIVE: Febuxostat and benzbromarone are two common drugs for the treatment of gout, but the clinical efficacy of these two drugs is controversial. This meta-analysis aimed to compare the efficacy of febuxostat and benzbromarone in the treatment of gout. MATERIALS AND METHODS: PubMed, Embase, and the Cochrane Library were searched for articles related to febuxostat and benzbromarone in the treatment of gout from inception to January 7, 2023. Titles and abstracts were reviewed in accordance with predesigned inclusion and exclusion criteria, and data were extracted independently. The Newcastle-Ottawa Scale (NOS) was used to evaluate the quality of the studies, and the continuous variables were expressed as the standard mean square error (SMD) by STATA 16 (Stata Corp., College Station, TX, USA). The sensitivity analysis was conducted by randomly removing a study, and the heterogeneity was analyzed by funnel plots and Egger's test. RESULTS: According to the search strategy, a total of 1,043 publications were retrieved from the three aforementioned databases, of which 45 publications were excluded due to duplication. Fourteen studies remained after screening titles and abstracts, and a total of 7 studies met the inclusion criteria after a comprehensive evaluation of the 14 studies. Meta-analysis showed that the uric acid (UA)-reducing effect of febuxostat is better than that of benzbromarone, while febuxostat showed a better ability to improve the estimated glomerular filtration rate (eGFR) and reduce Cr and blood urea nitrogen (BUN). In terms of hepatotoxicity, benzbromarone was not as potent as febuxostat in increasing alanine transaminase (ALT) and aspartate transaminase (AST), suggesting that benzbromarone has less hepatotoxicity. Moreover, there was no significant difference in the effect on blood lipid levels between the two drugs. CONCLUSIONS: The beneficial effect of febuxostat on renal function-related indexes such as the eGFR, Cr and BUN is significant, while benzbromarone is more effective in reducing UA and has relatively less hepatotoxicity. The specific efficacy of the two drugs needs to be confirmed by further research.

Formation of reactive metabolites of benzbromarone in humanized-liver mice.

Benzbromarone, a uricosuric drug, has the potential to cause serious hepatotoxicity. Several studies have shown the formation of reactive metabolites of benzbromarone and their association with hepatotoxicity in mice. However, it is unknown whether those reactive metabolites are generated in humans in vivo. In the present study, we firstly investigated the pharmacokinetic profiles of benzbromarone in chimeric TK-NOG mice transplanted with human hepatocytes (humanized-liver mice) and then investigated whether reactive metabolites could be generated. The area under the plasma concentration-time curve ratio of benzbromarone and its major metabolites (benzbromarone: 1'-hydroxy benzbromarone: 6-hydroxy benzbromarone) in humanized-liver mice was 1: 1.2: 0.7, which was similar to that reported in humans. In addition, glutathione conjugates and their further metabolites derived from the epoxidation of the benzofuran ring and 1',6-dihydroxylation of benzbromarone were detected in the livers, urine and plasma. Furthermore, their peak intensities in mass spectrometry showed markedly higher levels compared with those of TK-NOG mice. These results suggested that the metabolic profiles of benzbromarone in humanized-liver mice were similar to those in humans and that the reactive metabolites detected in humanized-liver mice could be generated and are associated with the benzbromarone-induced hepatotoxicity in humans.

Short-Term Hyperuricemia Leads to Structural Retinal Changes That Can be Reversed by Serum Uric Acid Lowering Agents in Mice.

Purpose: Metabolic disorders have been implicated in ocular diseases, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR). Recently, hyperuricemia (HUA) has been proposed as another risk factor for AMD, although no cause-and-effect experimental data have been published. In this study, we investigated whether HUA would initiate AMD or related retinal damages in hyperuricemic mice. Methods: HUA was induced in male ICR mice by dietary supplements of uric acid and oxonic acid potassium salt, with or without treatments by allopurinol or benzbromarone for various durations. Serum uric acid and angiotensin II concentrations were measured by enzyme-linked immunosorbent assay (ELISA) at regular intervals. The retinal damages were assessed by hematoxylin and eosin staining, immunostaining, and TUNEL assay. The cause-and-effect of HUA was compared among the study groups. Results: The results showed that the total thickness of photoreceptor inner and outer segments, as well as the thickness of the photoreceptor outer segment alone, were reduced under HUA. Furthermore, HUA elevated serum angiotensin II, which indicated activation of the renin-angiotensin system (RAS), leading to higher matrix metalloproteinase-2 (MMP-2) expression, and glial activation in the ganglion cell layer. HUA also led to the reduction of retinal pigment epithelium gap junction protein connexin-43 and apoptosis. Uric acid lowering agents, allopurinol or benzbromarone, were effective in ameliorating the impairments. Conclusions: HUA may pose as a causative factor of retinal injuries. The reduction of serum uric acid may reduce the detrimental effects caused by HUA.

Discovery of novel benzbromarone analogs with improved pharmacokinetics and benign toxicity profiles as antihyperuricemic agents.

Benzbromarone (BM) is a potent URAT1 inhibitor approved for the treatment of gout. However, the low URAT1-selectivity and hepatotoxcity limit its clinical use. To solve these problems, we rationally designed and synthesized a series of BM derivatives by chemotype hybridization and bioisosteric replacement. Most compounds exhibited potent inhibitory activities against URAT1 with IC50 values ranging from 5.83 µM to 0.80 µM. Among them, JNS4 exhibited the highest URAT1 inhibitory activity with an IC50 of 0.80 µM, comparable to that of BM (IC50 = 0.53 µM). Molecular dynamic simulations showed that JNS4 formed π-cation interaction with R477, the same as BM. Different from BM, JNS4 bound to W357 and H245 via π-π interactions and formed a hydrogen bond with S35, which might contribute to the high URAT1 binding affinity of JNS4. JNS4 hardly inhibited GLUT9 (IC50 > 20 µM), another urate reabsorption transporter. In addition, JNS4 showed little inhibitory effects against OAT1 and ABCG2 with IC50 of 4.04 µM and 10.16 µM, respectively. Importantly, JNS4 displayed higher in vivo urate-lowering effects at doses of 1-4 mg/kg in a mouse model of hyperuricemia, as compared to BM and lesinurad. Furthermore, JNS4 possessed favorable pharmacokinetic properties with an oral bioavailability of 55.28%, significantly higher than that of BM (36.11%). Moreover, JNS4 demonstrated benign toxicity profiles (no cytotoxicities against HepG2 and HK2 cells; no hepatic and renal toxicities observed in vivo). Collectively, these results suggest that JNS4 represents a novel, safe and selective URAT1 inhibitor with excellent druggabilities and is worthy of further investigation as an anti-hyperuricemic agent.

Superiority of Low-Dose Benzbromarone to Low-Dose Febuxostat in a Prospective, Randomized Comparative Effectiveness Trial in Gout Patients With Renal Uric Acid Underexcretion.

OBJECTIVE: The predominant mechanism driving hyperuricemia in gout is renal uric acid underexcretion; however, the standard urate-lowering therapy (ULT) recommendation is first-line xanthine oxidase inhibitor (XOI), irrespective of the cause of hyperuricemia. This comparative effectiveness clinical trial was undertaken to compare first-line nontitrated low-dose benzbromarone (LDBen) uricosuric therapy to XOI ULT with low-dose febuxostat (LDFeb) in gout patients with renal uric acid underexcretion. METHODS: We conducted a prospective, randomized, single-center, open-label trial in men with gout and renal uric acid underexcretion (defined as fractional excretion of urate <5.5% and uric acid excretion ≤600 mg/day/1.73 m2 ). A total of 196 participants were randomly assigned to receive LDBen 25 mg daily or LDFeb 20 mg daily for 12 weeks. All participants received daily urine alkalization with oral sodium bicarbonate. The primary end point was the rate of achieving the serum urate target of <6 mg/dl. RESULTS: More participants in the LDBen group achieved the serum urate target than those in the LDFeb group (61% compared to 32%, P < 0.001). Rates of adverse events, including gout flares and urolithiasis, did not differ between groups, with the exception of greater transaminase elevation in the LDFeb group (4% for LDBen compared to 15% for LDFeb, P = 0.008). CONCLUSION: Compared to LDFeb, LDBen has superior urate-lowering efficacy and similar safety in treating relatively young and healthy patients with renal uric acid underexcretion-type gout.

Beneficial herb-drug interaction of Gnaphalium affine extract on benzbromarone: A pharmacokinetic and pharmacodynamic study in rats.

BACKGROUND: Gnaphalium affine D. Don extract (GAD) enhanced efficacy and reduced toxicity of benzbromarone (BBR) in combination use. However, little is known about effects of GAD on the pharmacokinetics (PKs) and metabolic enzymes of BBR. PURPOSE: To investigate the pharmacokinetic (PK) and pharmacodynamic (PD) mechanism of the herb-drug interactions (HDIs) between GAD and BBR. STUDY DESIGN AND METHODS: Intragastric single BBR (4.5 or 50 mg/kg), single BBR (4.5 or 50 mg/kg) + single GAD (450 mg/kg, 2 h after BBR-administration), or single BBR (4.5 or 50 mg/kg) + multiple GAD (450 mg/kg/day, once daily for 7 days) were administered to both sexes for BBR PK studies in normal rats. Intragastric multiple BBR (4.5 mg/kg/day), or multiple BBR (4.5 mg/kg/day) + multiple GAD (450 mg/kg/day, 2 h after BBR-administration) were administered for BBR PK and PD studies in male rats with hyperuricemic nephropathy (HN). The cumulative anti-hyperuricemic effects of BBR and BBR+GAD were determined by plasma uric acid (UA) concentration-time curve and area under curve (AUCUA). An in vivo cocktail approach was employed to determine the effects of GAD on cytochrome P450 (CYP) 2C11(9) and 1A2 - mediated drug metabolism. RESULTS: In normal rats, the repeated dose administration of GAD induced a significant increase of BBR AUC and prolonged the mean residence time (MRT) (p < 0.05). systemic exposure to BBR and metabolically derived hydroxybenzbromarones was significantly greater in female compared with male rats (p < 0.05). In HN rats, post-administration of GAD resulted in significantly higher bioavailability and enterohepatic recycling (ER) of BBR relative to the BBR alone administrated group from the prolongation of terminal elimination half-life (T1/2) and MRT of BBR (p < 0.05). Significantly higher urate-lowering effect of BBR+GAD compared with BBR alone was generally observed at post-dosing most time points with a maximal effect of 84.3% (acute treatment), 71.4% (7-day subchronic treatment) and 82.5% (14-day subchronic treatment) reduction in UA levels. Additionally, GAD showed a significant inhibitory effect on CYP2C11(9)-mediated tolbutamide (probe substrate) metabolism with ≥ 1.25 but < 2-fold increase in AUCtolbutamide. CONCLUSIONS: PD synergism demonstrated with the BBR+GAD combination could be explained by the PK interaction observed partially from CYP2C11(9)-mediation and enterohepatic recycling.