Risk of urolithiasis associated with allopurinol versus benzbromarone among patients with gout: a population-based cohort study.

OBJECTIVES: To compare the risk of urolithiasis in gout patients initiating allopurinol, a xanthine oxidase inhibitor, vs benzbromarone, a uricosuric. METHODS: Using the 2011-20 Korea National Health Insurance Service database, we conducted a cohort study on gout patients initiating allopurinol vs benzbromarone as the first-line urate-lowering treatment. The primary outcome was a new onset urinary stone. The secondary outcome was a stone requiring intervention. We estimated hazard ratios (HRs) and 95% CIs using Cox proportional hazard models with a 5:1 ratio propensity-score matching on >80 variables. Subgroup analyses were done by age, sex, thiazide use and cardiovascular risk. RESULTS: 61 300 allopurinol initiators PS-matched on 12 260 benzbromarone initiators were included (mean age 59 years, 79% male). During a mean follow-up of 322 days, 619 urolithiasis cases occurred with an incidence rate of 0.87 per 100 person-years in allopurinol and 1.39 in benzbromarone initiators, showing a HR of 0.64 (95% CI, 0.51-0.80). Approximately 44% of urinary stones required intervention with a HR of 0.61 (95% CI, 0.43-0.88). The lower risk associated with allopurinol compared with benzbromarone persisted across subgroups but was greater in the high than non-high cardiovascular risk subgroup (P for interaction = 0.02). CONCLUSION: This population-based cohort study found that allopurinol compared with benzbromarone was associated with a substantially lower risk of urolithiasis particularly in the presence of the high cardiovascular risk. This finding provides important safety information for clinicians' decision-making on urate-lowering treatments of different mechanisms of action.

Attenuation of LPS-Induced Lung Injury by Benziodarone via Reactive Oxygen Species Reduction.

As overproduction of reactive oxygen species (ROS) causes various diseases, antioxidants that scavenge ROS, or inhibitors that suppress excessive ROS generation, can be used as therapeutic agents. From a library of approved drugs, we screened compounds that reduced superoxide anions produced by pyocyanin-stimulated leukemia cells and identified benzbromarone. Further investigation of several of its analogues showed that benziodarone possessed the highest activity in reducing superoxide anions without causing cytotoxicity. In contrast, in a cell-free assay, benziodarone induced only a minimal decrease in superoxide anion levels generated by xanthine oxidase. These results suggest that benziodarone is an inhibitor of NADPH oxidases in the plasma membrane but is not a superoxide anion scavenger. We investigated the preventive effect of benziodarone on lipopolysaccharide (LPS)-induced murine lung injury as a model of acute respiratory distress syndrome (ARDS). Intratracheal administration of benziodarone attenuated tissue damage and inflammation via its ROS-reducing activity. These results indicate the potential application of benziodarone as a therapeutic agent against diseases caused by ROS overproduction.

Design, synthesis, and biological studies of dual URAT1 inhibitor and FXR agonist based on benzbromarone.

With increased unhealthy dietary patterns and a sedentary lifestyle, the prevalence of hyperuricemia is growing rapidly, placing a tremendous burden on the public health system. Persistent hyperuricemia in extreme cases induces gout, gouty arthritis, and other metabolic diseases. Benzbromarone is a potent human urate transporter 1 (URAT1) inhibitor that is widely used as a uric acid-lowering drug. Recent studies indicated that benzbromarone can also activate farnesoid X receptor (FXR), whereas its agonistic activity on FXR is rather poor. Mounting evidence suggested that the etiology of gout is directly related to NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasomes, and FXR suppresses the expression of NLRP3 in various ways. Therefore, the dual URAT1 inhibitor and FXR agonist may exert synergistic effects on decreasing uric acid (UA) levels and inhibiting inflammation. To obtain a better dual URAT1 inhibitor and FXR agonist, we performed the structure-based drug design (SBDD) strategy to improve the FXR activation of benzbromarone by forming strong interactions with ARG331 in FXR binding pocket. All of these efforts lead to the identification of compound 4, which exerts better activity on FXR and uric acid-lowering effect than benzbromarone.

Cardiovascular risk associated with allopurinol vs. benzbromarone in patients with gout.

AIMS: With the high prevalence of gout and associated cardiovascular (CV) diseases, information on the comparative CV safety of individual urate-lowering drugs becomes increasingly important. However, few studies examined the CV risk of uricosuric agents. We compared CV risk among patients with gout who initiated allopurinol vs. benzbromarone. METHODS AND RESULTS: Using the Korean National Health Insurance claims data (2002-17), we conducted a cohort study of 124 434 gout patients who initiated either allopurinol (n = 103 695) or benzbromarone (n = 20 739), matched on propensity score at a 5:1 ratio. The primary outcome was a composite CV endpoint of myocardial infarction, stroke/transient ischaemic attack, or coronary revascularization. To account for competing risk of death, we used cause-specific hazard models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the outcomes comparing allopurinol initiators with benzbromarone. Over a mean follow-up of 1.16 years, 2258 patients developed a composite CV event. The incidence rate of the composite CV event was higher in allopurinol initiators (1.81 per 100 person-years) than benzbromarone (1.61 per 100 person-years) with a HR of 1.22 (95% CI 1.05-1.41). The HR for all-cause mortality was 1.66 (95% CI 1.43-1.93) among allopurinol initiators compared with benzbromarone. CONCLUSION: In this large population-based cohort of gout patients, allopurinol was associated with an increased risk of composite CV events and all-cause mortality compared to benzbromarone. Benzbromarone may reduce CV risk and mortality in patients with gout, although more studies are necessary to confirm our findings and to advance our understanding of the underlying mechanisms.

Interaction of Benzbromarone with Subdomains IIIA and IB/IIA on Human Serum Albumin as the Primary and Secondary Binding Regions.

Benzbromarone has been used for the treatment of gout for more than 30 years. Although it shows a high level of binding to plasma proteins (>99%), our knowledge of this binding is not sufficiently extensive to permit us to understand its pharmacokinetics and pharmacodynamics. To address this issue in more detail, we characterized the binding of benzbromarone to human serum albumin (HSA), the most abundant protein in plasma. Equilibrium dialysis and circular dichroism findings indicated that benzbromarone binds strongly to one primary as well as to multiple secondary sites on HSA and that the bromine atoms of benzbromarone play important roles in this high affinity binding. An X-ray crystallographic study revealed that benzbromarone molecules bind to hydrophobic pockets within subdomains IB, IIA, and IIIA. Inhibition experiments using site specific ligands (subdomain IB; fusidic acid, IIA; warfarin, IIIA; diazepam) indicated that the primary and secondary binding sites that benzbromarone binds to are within subdomains IIIA and IB/IIA, respectively. Lastly, a study of the effect of fatty acids on the benzbromarone-HSA interaction suggested that benzbromarone, when displaced from subdomain IIIA by sodium oleate, could transfer to subdomains IB or IIA. Thus, these data will permit more relevant assessments of the displacement interactions of benzbromarone especially in cases of co-administered drugs or endogenous compounds that also bind to subdomain IIIA. In addition, the findings presented herein will also be useful for designing drug combination therapy in which pharmacokinetic and pharmacodynamic performance need to be controlled.

Novel monocyclic amide-linked phenol derivatives without mitochondrial toxicity have potent uric acid-lowering activity.

Although benzbromarone (BBR) is a conventional, highly potent uricosuric drug, it is not a standard medicine because it causes rare but fatal fulminant hepatitis. We transformed the bis-aryl ketone structure of BBR to generate novel monocyclic amide-linked phenol derivatives that should possess uric acid excretion activity without adverse properties associated with BBR. The derivatives were synthesized and tested for uric acid uptake inhibition (UUI) in two assays using either urate transporter 1-expressing cells or primary human renal proximal tubule epithelial cells. We also evaluated their inhibitory activity against mitochondrial respiration as a critical mitochondrial toxicity parameter. Some derivatives with UUI activity had no mitochondrial toxicity, including compound 3f, which effectively lowered the plasma uric acid level in Cebus apella. Thus, 3f is a promising candidate for further development as a uricosuric agent.

Implementation Status of Liver Function Tests for Monitoring Benzbromarone-Induced Hepatotoxicity: An Epidemiological Survey Using the Japanese Claims Database.

A major adverse effect of benzbromarone is hepatotoxicity. Therefore, periodic liver function tests are required at least for the first 6 months of benzbromarone administration. However, it is not clear whether the relevant blood tests are implemented appropriately. Here, we performed a cross-sectional survey of the implementation status of liver function tests in patients who were newly prescribed benzbromarone, using the Japanese large claims database. Male patients who were newly prescribed benzbromarone from January 2010 to December 2016 were included. We targeted patients who continued benzbromarone during the observation period (up to 180 d from the start of administration). The primary endpoint was the proportion of patients in whom periodic liver function tests were implemented. A periodic liver function test was defined as one or more liver function tests performed during both 1-90 and 91-180 d of initial benzbromarone administration. We labeled the tests as a "periodic test" or "non-periodic test" based on whether periodic liver function tests were performed or not, respectively. Furthermore, factors influencing non-periodic test were analyzed. Periodic testing was implemented only in 28.7% of patients. Additionally, factors such as number of hospital beds ≤19 (compared to 100-199 beds) and duration of the first prescription of benzbromarone were associated with non-periodic testing. Our study revealed that periodic liver function tests are not performed sufficiently in Japan. Thus, clinicians prescribing benzbromarone should be educated about the test. Our blood-test-based approach should be applied to other drugs and countries in future research.

Developing, optimizing, and assessing a green electrophoretic method for determination of benzbromarone and allopurinol with its active metabolite in biological and pharmaceutical matrices.

A combination of allopurinol and benzbromarone is a common gout treatment protocol. A suboptimal response to allopurinol in patients is very common due to its pharmacokinetics variability. Moreover, the safe doses of benzbromarone is very crucial in patients with hepatic diseases. This raised the inquisitiveness to develop and optimize a capillary zone electrophoresis method for the determination of allopurinol and benzbromarone in their coformulation and in the presence of oxypurinol, the active metabolite of allopurinol, in biological and pharmaceutical matrices. The method greenness profile was assessed using green metric tools the "National Environmental Method Index," the "Analytical Eco-Scale," and the "Green Analytical Procedure Index" by which the method proved to be ecofriendly. The method was successfully applied for the analysis of the pharmaceutical preparation and urine samples spiked with both drugs and the active metabolite. The linearity range was 25.0-250.0 µg/mL for benzbromarone, 50.0-350.0 µg/mL for allopurinol, and 100.0-500.0 µg/mL for oxypurinol. The recoveries were 99.60 ± 0.67, 99.89 ± 0.98, and 98.71 ± 1.18% for benzbromarone, allopurinol, and oxypurinol, respectively. The analysis results indicate potential usefulness of capillary zone electrophoresis as a competitive and greener method of analysis in biological and quality control labs.

Development and greenness assessment of a stability-indicating HPLC-DAD method for simultaneous determination of allopurinol and benzbromarone.

The growing interest in Green Analytical Chemistry (GAC) principles through the replacement of polluting analytical procedures with greener ones, has encouraged us to develop an eco-friendly stability-indicating HPLC with diode array detection method (HPLC-DAD) for simultaneous determination of allopurinol (ALP) and benzbromarone (BNZ). Effective separation was accomplished using Durashell C18 column (4.6 × 250 mm, 5 µm particle size) with gradient elution of the mobile phase composed of 0.02 M ammonium acetate (pH 5.0) and methanol. Quantification of ALP and BNZ was based on measuring their peak areas at 251 nm. ALP and BNZ peaks eluted at retention times 4.85 and 10.30 min respectively. The proposed HPLC procedure was carefully validated in terms of system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection, and quantification limits. The linearity range for both ALP and BNZ was 5-100 µg/mL with correlation coefficients >0.9999. Forced degradation conditions of neutral, acidic, and alkaline hydrolysis, oxidation, and thermal degradation were applied on both drugs. Good resolution of the drugs from their forced degradation products proved that the proposed method is stability-indicating. In addition, the resolution of both drugs from about 10 pharmacologically or chemically related pharmaceutical compounds of different medicinal categories showed the high specificity of the proposed method. The validated HPLC method was successfully applied to the simultaneous determination of both drugs in their tablet dosage forms. Furthermore, greenness assessment and comparison with previously published methods were carried out using two different GAC metrics, namely, the national environmental method index (NEMI) and the analytical Eco-Scale.

Dotinurad versus benzbromarone in Japanese hyperuricemic patient with or without gout: a randomized, double-blind, parallel-group, phase 3 study.

BACKGROUND: Dotinurad is a novel selective urate reabsorption inhibitor that reduces serum urate levels in hyperuricemic patients with or without gout by selectively inhibiting urate transporter 1. This study was conducted to compare the efficacy and safety of dotinurad with those of benzbromarone. METHODS: In this 14-week, randomized, multicenter, double-blind, parallel-group, dose escalation, benzbromarone-controlled, phase 3 study, hyperuricemic patients with or without gout were randomized to two groups that received either dotinurad 2 mg or benzbromarone 50 mg. Dotinurad or benzbromarone was administered once a day for 14 weeks. The primary endpoint was the percent change in serum uric acid level from the baseline to the final visit. RESULTS: A total of 201 Japanese hyperuricemic patients with or without gout (dotinurad: 102, benzbromarone: 99) received at least one dose of the study drug. The mean percent change in serum uric acid level from the baseline to the final visit in the dotinurad and benzbromarone groups was 45.9% and 43.8%, respectively. Non-inferiority of dotinurad 2 mg to benzbromarone 50 mg in lowering serum uric acid was verified by the predefined non-inferiority margin (95% CI - 1.27 to 5.37%). The incidence of adverse events and adverse drug reactions was comparable between the two groups. CONCLUSION: Dotinurad 2 mg was verified to have a non-inferior serum uric acid lowering effect compared with benzbromarone 50 mg, in Japanese hyperuricemic patients with or without gout. CLINICALTRIALS. GOV IDENTIFIER: NCT03100318.

Repurposing Benzbromarone for Familial Amyloid Polyneuropathy: A New Transthyretin Tetramer Stabilizer.

Transthyretin (TTR) is a homotetrameric protein involved in human amyloidosis, including familial amyloid polyneuropathy (FAP). Discovering small-molecule stabilizers of the TTR tetramer is a therapeutic strategy for these diseases. Tafamidis, the only approved drug for FAP treatment, is not effective for all patients. Herein, we discovered that benzbromarone (BBM), a uricosuric drug, is an effective TTR stabilizer and inhibitor against TTR amyloid fibril formation. BBM rendered TTR more resistant to urea denaturation, similarly to iododiflunisal (IDIF), a very potent TTR stabilizer. BBM competes with thyroxine for binding in the TTR central channel, with an IC50 similar to IDIF and tafamidis. Results obtained by isothermal titration calorimetry (ITC) demonstrated that BBM binds TTR with an affinity similar to IDIF, tolcapone and tafamidis, confirming BBM as a potent binder of TTR. The crystal structure of the BBM-TTR complex shows two molecules binding deeply in the thyroxine binding channel, forming strong intermonomer hydrogen bonds and increasing the stability of the TTR tetramer. Finally, kinetic analysis of the ability of BBM to inhibit TTR fibrillogenesis at acidic pH and comparison with other stabilizers revealed that benzbromarone is a potent inhibitor of TTR amyloidogenesis, adding a new interesting scaffold for drug design of TTR stabilizers.

Pharmacological Inhibition and Activation of the Ca2+ Activated Cl- Channel TMEM16A.

TMEM16A is a Ca2+ activated Cl- channel with important functions in airways, intestine, and other epithelial organs. Activation of TMEM16A is proposed as a therapy in cystic fibrosis (CF) to reinstall airway Cl- secretion and to enhance airway surface liquid (ASL). This CFTR-agnostic approach is thought to improve mucociliary clearance and lung function in CF. This could indeed improve ASL, however, mucus release and airway contraction may also be induced by activators of TMEM16A, particularly in inflamed airways of patients with asthma, COPD, or CF. Currently, both activators and inhibitors of TMEM16A are developed and examined in different types of tissues. Here we compare activation and inhibition of endogenous and overexpressed TMEM16A and analyze potential off-target effects. The three well-known blockers benzbromarone, niclosamide, and Ani9 inhibited both TMEM16A and ATP-induced Ca2+ increase by variable degrees, depending on the cell type. Niclosamide, while blocking Ca2+ activated TMEM16A, also induced a subtle but significant Ca2+ store release and inhibited store-operated Ca2+ influx. Niclosamide, benzbromarone and Ani9 also affected TMEM16F whole cell currents, indicating limited specificity for these inhibitors. The compounds Eact, cinnamaldehyde, and melittin, as well as the phosphatidylinositol diC8-PIP2 are the reported activators of TMEM16A. However, the compounds were unable to activate endogenous TMEM16A in HT29 colonic epithelial cells. In contrast, TMEM16A overexpressed in HEK293 cells was potently stimulated by these activators. We speculate that overexpressed TMEM16A might have a better accessibility to intracellular Ca2+, which causes spontaneous activity even at basal intracellular Ca2+ concentrations. Small molecules may therefore potentiate pre-stimulated TMEM16A currents, but may otherwise fail to activate silent endogenous TMEM16A.

Benzbromarone aggravates hepatic steatosis in obese individuals.

As a widely used anti-gout drug, benzbromarone has been found to induce hepatic toxicity in patients during clinical treatment. Previous studies have reported that benzbromarone is metabolized via cytochrome P450, thus causing mitochondrial toxicity in hepatocytes. In this study, we found that benzbromarone significantly aggravated hepatic steatosis in both obese db/db mice and high fat diet (HFD)-induced obese (DIO) mouse models. However, benzbromarone had less effect on the liver of lean mice. It was found that the expression of mRNAs encoding lipid metabolism and some liver-specific genes were obviously disturbed in benzbromarone-treated DIO mice compared to the control group. The inflammatory and oxidative stress factors were also activated in the liver of benzbromarone-treated DIO mice. In accordance with the in vivo results, an in vitro experiment using human hepatoma HepG2 cells also confirmed that benzbromarone promoted intracellular lipid accumulation under high free fatty acids (FFAs) conditions by regulating the expression of lipid metabolism genes. Importantly, prolonged treatment of benzbromarone significantly increased cell apoptosis in HepG2 cells in the presence of high FFAs. In addition, in benzbromarone-treated hyperuricemic patients, serum transaminase levels were positively correlated with patients' obesity level. CONCLUSION: This study demonstrated that benzbromarone aggravated hepatic steatosis in obese individuals, which could subsequently contribute to hepatic cell injury, suggesting a novel toxicological mechanism in benzbromarone-induced hepatotoxicity.

Synthesis of novel benzbromarone derivatives designed to avoid metabolic activation.

We synthesized six novel BBR derivatives that were designed to avoid metabolic activation via ipso-substitution and evaluated for their degree of toxicity and hURAT1 inhibition. It was found that all of the derivatives demonstrate lower cytotoxicity in mouse hepatocytes and lower levels of metabolic activation than BBR, while maintaining their inhibitory activity toward the uric acid transporter. We propose that these derivatives could serve as effective uricosuric agents that have much better safety profiles than BBR.

Role of the OATP Transporter Family and a Benzbromarone-SensitiveEfflux Transporter in the Hepatocellular Disposition of Vincristine.

PURPOSE: Vincristine is known to interfere with OATP-mediated uptake of other compounds, hinting that vincristine itself could be a substrate of OATP transporters. The present study therefore aimed to investigate the role of OATP transporters in the hepatocellular disposition of vincristine. METHODS: Vincristine uptake was studied in suspended rat and human hepatocytes as well as OATP-transfected Chinese hamster ovary (CHO) cells in the absence and presence of OATP transporter inhibitors. Membrane vesicles containing MDR1 or MRP1/2/3 were used to directly assess the role of these efflux transporters in vincristine disposition. RESULTS: Uptake in suspended rat hepatocytes was temperature-dependent and could be inhibited by a range of OATP inhibitors. Furthermore, the MRP-inhibitor benzbromarone, but none of the tested MDR1 inhibitors, reduced vincristine efflux in rat and human suspended hepatocytes. OATP1B1-, OATP1B3- and OATP2B1- transfected CHO cells showed significantly increased vincristine uptake as compared to wild-type cells. Moreover, uptake in OATP-transfected CHO cells was reduced by OATP inhibitors. However, uptake studies in suspended human hepatocytes showed that only 10% of the total vincristine uptake process could be attributed to OATP-mediated transport. Studies with transporter-expressing membrane vesicles confirmed vincristine as an MDR1 substrate, while MRP1/2/3-mediated transport of vincristine could not be observed with this model system. CONCLUSIONS: Our findings show the involvement of OATP transporters in the disposition of vincristine in rat and human hepatocytes. However, in both species, hepatic uptake is overshadowed by a benzbromarone-sensitive efflux mechanism, possibly MRP3.

Association of a reactive intermediate derived from 1',6-dihydroxy metabolite with benzbromarone-induced hepatotoxicity.

Treatment with benzbromarone can be associated with liver injury, but the detailed mechanism remains unknown. Our recent studies demonstrated that benzbromarone was metabolized to 1',6-dihydroxybenzbromarone and followed by formation of reactive intermediates that were trapped by glutathione, suggesting that the reactive intermediates may be responsible for the liver injury. The aim of this study was to clarify whether the reactive intermediates derived from 1',6-dihydroxybenzbromarone is a risk factor of liver injury in mice. An incubation study using mouse liver microsomes showed that the rates of formation of 1',6-dihydroxybenzbromarone from benzbromarone were increased by pretreatment with dexamethasone. Levels of a hepatic glutathione adduct derived from 1',6-dihydroxybenzbromarone were increased by pretreatment with dexamethasone. Furthermore, plasma alanine amino transferase activities were increased in mice treated with benzbromarone after pretreatment with dexamethasone. The results suggest that the reactive intermediate derived from 1',6-dihydroxybenzbromarone may be associated with liver injury.

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.

The safety and efficacy of benzbromarone in gout in Aotearoa New Zealand.

BACKGROUND: Benzbromarone is a potent uricosuric but is not widely available due to concerns about hepatotoxicity. In Aotearoa New Zealand, benzbromarone has been available since April 2013, subject to funding restrictions, for patients with inadequate urate-lowering response or intolerance to allopurinol and probenecid. AIM: To assess the safety and efficacy of benzbromarone in a real-life setting. METHODS: All patients who received funding for benzbromarone from 1 April 2013 to 30 September 2014 were identified. Prescribers were sent a questionnaire for each individual. Information on demographics, efficacy of previous urate-lowering drugs and reasons for discontinuation were collected. Specific information about the dose, effect on serum urate, adverse effects and liver function tests after commencing benzbromarone was recorded. RESULTS: Completed questionnaires were returned for 123 of 164 (75%) patients. Mean (SD) serum urate prior to benzbromarone was 0.57 (0.12) mmol/L, and estimated glomerular filtration rate was 50.3 (22.8) mL/min/1.73 m(2) . The median dose of benzbromarone was 100 mg/day (25-200 mg/day). Six months after commencing benzbromarone, mean (SD) serum urate was 0.35 (0.12) mmol/L. Benzbromarone-related adverse events included rash (n = 4), diarrhoea (n = 9), nausea (n = 6) and urate stones (n = 3). Liver function test abnormalities were uncommon and tended to be mild. There were 14 patient deaths; none was considered related to benzbromarone. Allopurinol had been prescribed prior to benzbromarone in 117 of 123 patients; median maximum allopurinol dose was 200 mg/day (range 25-600 mg/day), and 19% patients received allopurinol >300 mg/day. CONCLUSION: Benzbromarone provides useful urate-lowering efficacy and does not appear unsafe in patients with gout. Urate-lowering therapy prescribing requires further optimisation.

Benzbromarone, Quercetin, and Folic Acid Inhibit Amylin Aggregation.

Human Amylin, or islet amyloid polypeptide (hIAPP), is a small hormone secreted by pancreatic ß-cells that forms aggregates under insulin deficiency metabolic conditions, and it constitutes a pathological hallmark of type II diabetes mellitus. In type II diabetes patients, amylin is abnormally increased, self-assembled into amyloid aggregates, and ultimately contributes to the apoptotic death of ß-cells by mechanisms that are not completely understood. We have screened a library of approved drugs in order to identify inhibitors of amylin aggregation that could be used as tools to investigate the role of amylin aggregation in type II diabetes or as therapeutics in order to reduce ß-cell damage. Interestingly, three of the compounds analyzed-benzbromarone, quercetin, and folic acid-are able to slow down amylin fiber formation according to Thioflavin T binding, turbidimetry, and Transmission Electron Microscopy assays. In addition to the in vitro assays, we have tested the effect of these compounds in an amyloid toxicity cell culture model and we have found that one of them, quercetin, has the ability to partly protect cultured pancreatic insulinoma cells from the cytotoxic effect of amylin. Our data suggests that quercetin can contribute to reduce oxidative damage in pancreatic insulinoma ß cells by modulating the aggregation propensity of amylin.

Metabolic activation of hepatotoxic drug (benzbromarone) induced mitochondrial membrane permeability transition.

The risk of drug-induced liver injury (DILI) is of great concern to the pharmaceutical industry. It is well-known that metabolic activation of drugs to form toxic metabolites (TMs) is strongly associated with DILI onset. Drug-induced mitochondrial dysfunction is also strongly associated with increased risk of DILI. However, it is difficult to determine the target of TMs associated with exacerbation of DILI because of difficulties in identifying and purifying TMs. In this study, we propose a sequential in vitro assay system to assess TM formation and their ability to induce mitochondrial permeability transition (MPT) in a one-pot process. In this assay system, freshly-isolated rat liver mitochondria were incubated with reaction solutions of 44 test drugs preincubated with liver microsomes in the presence or absence of NADPH; then, NADPH-dependent MPT pore opening was assessed as mitochondrial swelling. In this assay system, several hepatotoxic drugs, including benzbromarone (BBR), significantly induced MPT in a NADPH-dependent manner. We investigated the rationality of using BBR as a model drug, since it showed the most prominent MPT in our assay system. Both the production of a candidate toxic metabolite of BBR (1',6-(OH)2 BBR) and NADPH-dependent MPT were inhibited by several cytochrome P450 (CYP) inhibitors (clotrimazole and SKF-525A, 100µM). In summary, this assay system can be used to evaluate comprehensive metabolite-dependent MPT without identification or purification of metabolites.