Efficacy and tolerability of probenecid as urate-lowering therapy in gout; clinical experience in high-prevalence population

Anti-hyperuricemia bioactive peptides: a review on obtaining, activity, and mechanism of action

Hyperuricemia, a disorder of uric acid metabolism, serves as a significant risk factor for conditions such as hypertension, diabetes mellitus, renal failure, and various metabolic syndromes. The main contributors to hyperuricemia include overproduction of uric acid in the liver or impaired excretion in the kidneys. Despite traditional clinical drugs being employed for its treatment, significant health concerns persist. Recently, there has been growing interest in utilizing protein peptides sourced from diverse food origins to mitigate hyperuricemia. This article provides a comprehensive review of bioactive peptides with anti-hyperuricemia properties derived from animals, plants, and their products. We specifically outline the methods for preparing these peptides from food proteins and elucidate their efficacy and mechanisms in combating hyperuricemia, supported by in vitro and in vivo evidence. Uric acid-lowering peptides offer promising prospects due to their safer profile, enhanced efficacy, and improved bioavailability. Therefore, this review underscores significant advancements and contributions in identifying peptides capable of metabolizing purine and/or uric acid, thereby alleviating hyperuricemia. Moreover, it offers a theoretical foundation for the development of functional foods incorporating uric acid-lowering peptides.

Targeting Neutrophil Extracellular Traps in Gouty Arthritis: Insights into Pathogenesis and Therapeutic Potential

Gouty arthritis (GA) is an immune-mediated disorder characterized by severe inflammation due to the deposition of monosodium urate (MSU) crystals in the joints. The pathophysiological mechanisms of GA are not yet fully understood, and therefore, the identification of effective therapeutic targets is of paramount importance. Neutrophil extracellular traps (NETs), an intricate structure of DNA scaffold, encompassing myeloperoxidase, histones, and elastases - have gained significant attention as a prospective therapeutic target for gouty arthritis, due to their innate antimicrobial and immunomodulatory properties. Hence, exploring the therapeutic potential of NETs in gouty arthritis remains an enticing avenue for further investigation. During the process of gouty arthritis, the formation of NETs triggers the release of inflammatory cytokines, thereby contributing to the inflammatory response, while MSU crystals and cytokines are sequestered and degraded by the aggregation of NETs. Here, we provide a concise summary of the inflammatory processes underlying the initiation and resolution of gouty arthritis mediated by NETs. Furthermore, this review presents an overview of the current pharmacological approaches for treating gouty arthritis and summarizes the potential of natural and synthetic product-based inhibitors that target NET formation as novel therapeutic options, alongside elucidating the intrinsic challenges of these inhibitors in NETs research. Lastly, the limitations of HL-60 cell as a suitable substitute of neutrophils in NETs research are summarized and discussed. Series of recommendations are provided, strategically oriented towards guiding future investigations to effectively address these concerns. These findings will contribute to an enhanced comprehension of the interplay between NETs and GA, facilitating the proposition of innovative therapeutic strategies and novel approaches for the management of GA.

Probenecid ameliorates testosterone-induced benign prostatic hyperplasia: Implications of PGE-2 on ADAM-17/EGFR/ERK1/2 signaling cascade

Benign prostatic hyperplasia (BPH) is one of the most prevalent clinical disorders in the elderly. Probenecid (Prob) is a well-known FDA-approved therapy for gout owing to its uricosuric effect. The present study evaluated the use of Prob for BPH as a COX-2 inhibitor. Prob (100 and 200 mg/kg) was intraperitoneally injected into male Wistar rats daily for 3 weeks. In the second week, testosterone (3 mg/kg) was subcutaneously injected to induce BPH. Compared with BPH-induced rats, Prob treatment reduced prostate weight and index and improved histopathological architecture. The protease activity of ADAM-17/TACE and its ligands (TGF-α and TNF-α) were regulated by prob, which in turn abolished EGFR phosphorylation, and several inflammatory mediators (COX-2, PGE2, NF-κB (p65), and IL-6) were suppressed. By reducing the nuclear import of extracellular regulated kinase protein 1/2 (ERK1/2), Prob helped re-establish the usual equilibrium between antiapoptotic proteins like Bcl-2 and cyclin D1 and proapoptotic proteins like Bax. All of these data point to Prob as a promising treatment for BPH because of its ability to inhibit COX-2-syntheiszed PGE2 and control the ADAM-17/TGF-α-induced EGFR/ERK1/2 signaling cascade. These findings might help to repurpose Prob for the treatment of BPH.

Emerging Urate-Lowering Drugs and Pharmacologic Treatment Strategies for Gout: A Narrative Review

Hyperuricemia with consequent monosodium urate crystal deposition leads to gout, characterized by painful, incapacitating inflammatory arthritis flares that are also associated with increased cardiovascular event and related mortality risk. This narrative review focuses on emerging pharmacologic urate-lowering treatment (ULT) and management strategies in gout. Undertreated, gout can progress to palpable tophi and joint damage. In oral ULT clinical trials, target serum urate of < 6.0 mg/dL can be achieved in ~ 80-90% of subjects, with flare burden reduction by 1-2 years. However, real-world ULT results are far less successful, due to both singular patient nonadherence and prescriber undertreatment, particularly in primary care, where most patients are managed. Multiple dose titrations commonly needed to optimize first-line allopurinol ULT monotherapy, and substantial potential toxicities and other limitations of approved, marketed oral monotherapy ULT drugs, promote hyperuricemia undertreatment. Common gout comorbidities with associated increased mortality (e.g., moderate-severe chronic kidney disease [CKD], type 2 diabetes, hypertension, atherosclerosis, heart failure) heighten ULT treatment complexity and emphasize unmet needs for better and more rapid clinically significant outcomes, including attenuated gout flare burden. The gout drug armamentarium will be expanded by integrating sodium-glucose cotransporter-2 (SGLT2) inhibitors with uricosuric and anti-inflammatory properties as well as clinically indicated antidiabetic, nephroprotective, and/or cardioprotective effects. The broad ULT developmental pipeline is loaded with multiple uricosurics that selectively target uric acid transporter 1 (URAT1). Evolving ULT approaches include administering selected gut anaerobic purine degrading bacteria (PDB), modulating intestinal urate transport, and employing liver-targeted xanthine oxidoreductase mRNA knockdown. Last, emerging measures to decrease the immunogenicity of systemically administered recombinant uricases should simplify treatment regimens and further improve outcomes in managing the most severe gout phenotypes.

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.

Early urate-lowering therapy in gouty arthritis with acute flares: a double-blind placebo controlled clinical trial

BACKGROUND

Gouty arthritis (GA) is a chronic systemic disease with recurrent acute monoarthritis. In a previous study, a higher incidence of acute flares was observed during the initial marked decrease in serum urate level. Our study evaluated the effect of early urate-lowering therapy in patients with acute GA flares.

METHODS

This study included 40 patients with acute GA; of them, 20 received colchicine 0.5 mg colchicine twice daily, while 20 received probenecid 500 mg and colchicine 0.5 mg twice daily. We evaluated GA severity and laboratory data for 2 weeks after the initial therapy. Medians and interquartile ranges (IQRs) were calculated to evaluate clinical presentations between these two groups.

RESULTS

Rapidly decreasing median serum uric acid levels was found in the patients treated with probenecid and colchicine compared with the patients treated with colchicine alone on day 8 (- 1.9 [IQR, - 3.7 to 0] vs 0.8 [IQR, - 0.1-2.2]; P < 0.001). However, the median decrease in visual analog scale score did not differ significantly between the two groups (- 5.5 [IQR, - 8.0 to - 3.0] vs - 3.5 [IQR, - 5.9 to - 2.0]; P = 0.080).

CONCLUSION

No significant increase was noted in acute gout flare severity or duration among GA patients treated with early aggressive control of hyperuricemia using probenecid plus colchicine.

Comparative efficacy and safety of uricosuric agents in the treatment of gout or hyperuricemia: a systematic review and network meta-analysis

OBJECTIVES

The current world witnesses a greatly increased prevalence and incidence of hyperuricemia and gout with unfortunately the comparative efficacy and safety of present available uricosuric agents remaining uncertain. We herein aimed to investigate the most appropriate uricosuric agent for gout or hyperuricemia patients.

METHOD

PubMed, Embase, Cochrane Library databases, and ClinicalTrials.gov from inception to 2 July 2022 were searched to retrieve eligible studies assessing efficacy and safety of uricosuric drugs in hyperuricemia or gout patients. Network meta-analysis was carried out using the Stata 16.0 software.

RESULTS

Twelve randomized controlled trials comprising 1851 patients were eventually included. Network meta-analysis showed that dotinurad 4 mg once daily, verinurad, dotinurad 2 mg once daily, dotinurad 1 mg once daily, and benzbromarone were the top 5 effective treatments to achieve target serum uric acid. Furthermore, dotinurad 4 mg once daily was more effective at achieving urate-lowering targets (RR of dotinurad 4 mg once daily vs. probenecid: 1.68, 95% CI [1.13; 2.50]) and safer (RR of probenecid vs. dotinurad 4 mg once daily: 1.77, 95% CI [0.69; 4.56]) than probenecid.

CONCLUSIONS

This network meta-analysis demonstrated an important absolute benefit of dotinurad 4 mg once daily to achieve target serum uric acid and low risk of adverse events for drug treatment of gout or hyperuricemia patients. Additionally, verinurad might be used as an alternative uricosuric therapeutic option to dotinurad. These findings provided further comprehensive insight into the treatment value of current uricosuric agents for gout or hyperuricemia. Key Points 1. This is the first systematic review and network meta-analysis examining the efficacy and safety of currently available uricosuric agents in gout or hyperuricemia patients. 2. Recommended doses of dotinurad 4mg once daily used for the treatment of gout or hyperuricemia patients can significantly decrease serum uric acid levels. 3. The present findings will provide further comprehensive insight into the treatment value of certain uricosuric agents for gout or hyperuricemia.

Blockade of Organic Anion Transport in Humans After Treatment With the Drug Probenecid Leads to Major Metabolic Alterations in Plasma and Urine

Probenecid is used to treat gout and hyperuricemia as well as increase plasma levels of antiviral drugs and antibiotics. In vivo, probenecid mainly inhibits the renal SLC22 organic anion transporters OAT1 (SLC22A6), OAT3 (SLC22A8), and URAT1 (SLC22A12). To understand the endogenous role of these transporters in humans, we administered probenecid to 20 healthy participants and metabolically profiled the plasma and urine before and after dosage. Hundreds of metabolites were significantly altered, indicating numerous drug-metabolite interactions. We focused on potential OAT1 substrates by identifying 97 metabolites that were significantly elevated in the plasma and decreased in the urine, indicating OAT-mediated clearance. These included signaling molecules, antioxidants, and gut microbiome products. In contrast, urate was the only metabolite significantly decreased in the plasma and elevated in the urine, consistent with an effect on renal reuptake by URAT1. Additional support comes from metabolomics analyses of our Oat1 and Oat3 knockout mice, where over 50% of the metabolites that were likely OAT substrates in humans were elevated in the serum of the mice. Fifteen of these compounds were elevated in both knockout mice, whereas six were exclusive to the Oat1 knockout and 4 to the Oat3 knockout. These may be endogenous biomarkers of OAT function. We also propose a probenecid stress test to evaluate kidney proximal tubule organic anion transport function in kidney disease. Consistent with the Remote Sensing and Signaling Theory, the profound changes in metabolite levels following probenecid treatment support the view that SLC22 transporters are hubs in the regulation of systemic human metabolism.

Review of Urate-Lowering Therapeutics: From the Past to the Future

We reviewed all currently available ULT, as well as any medications in development using following databases: United States Food and Drug Administration (FDA), European Medicines Agency (EMA), Japanese Pharmaceutical and Medical Devices Agency (PMDA), and ClinicalTrials.gov. We identified a total of 36 drugs, including 10 approved drugs, 17 in clinical testing phases, and 9 in preclinical developmental phases. The 26 drugs currently undergoing testing and development include 5 xanthine oxidase inhibitors, 14 uricosurics, 6 recombinant uricases, and one with multiple urate-lowering mechanisms of action. Herein, we reviewed the benefit and risk of each drug summarizing currently available drugs. New trials of uricosuric agents are underway to develop the new indication. New drugs are going on to improve the potency of recombinant uricase and to develop the new route administration of such as oral formulation. This review will provide valuable information on the properties, indications, and limitations of ULTs.

Critical appraisal of serum urate targets in the management of gout

Gout management involves two broad aspects: treatment of gout flares to provide rapid symptomatic relief and long-term urate-lowering therapy to lower serum urate sufficiently to prevent gout flares from occurring. All of the major rheumatology societies recommend a target serum urate of <5 mg/dl (<0.30 mmol/l) or <6 mg/dl (<0.36 mmol/l), both of which are below the point of saturation for urate and therefore lead to monosodium urate crystal dissolution. In this Review, we describe the rationale for treat-to-target urate approach in the long-term management of gout and the current evidence and controversy around the appropriate serum urate targets.

Probenecid-Blocked Pannexin-1 Channel Protects Against Early Brain Injury via Inhibiting Neuronal AIM2 Inflammasome Activation After Subarachnoid Hemorrhage

Aim

Previous studies have proved that inhibiting inflammasome activation provides neuroprotection against early brain injury (EBI) after subarachnoid hemorrhage (SAH), which is mainly focused on the microglial inflammatory response, but the potential role of neuronal inflammasome activation in EBI has not been clearly identified. This study examined whether the pannexin-1 channel inhibitor probenecid could reduce EBI after SAH by inhibiting neuronal AIM2 inflammasome activation.

Methods

There are in vivo and in vitro parts in this study. First, adult male SD rats were subjected to the endovascular perforation mode of SAH. The time course of pannexin-1 and AIM2 expressions were determined after SAH in 72 h. Brain water content, neurological function, AIM2 inflammasome activation, and inflammatory response were evaluated at 24 h after SAH in sham, SAH, and SAH + probenecid groups. In the in vitro part, HT22 cell treated with hemin was applied to mimic SAH. The expression of AIM2 inflammasome was detected by immunofluorescence staining. Neuronal death and mitochondrial dysfunction were determined by the LDH assay kit and JC-1 staining.

Results

The pannexin-1 and AIM2 protein levels were upregulated after SAH. Pannexin-1 channel inhibitor probenecid attenuated brain edema and improved neurological dysfunction by reducing AIM2 inflammasome activation and reactive oxygen species (ROS) generation after SAH in rats. Treating HT22 cells with hemin for 12 h resulted in AIM2 and caspase-1 upregulation and increased mitochondrial dysfunction and neuronal cell death. Probenecid significantly attenuated the hemin-induced AIM2 inflammasome activation and neuronal death.

Conclusions

AIM2 inflammasome is activated in neurons after SAH. Pharmacological inhibition of the pannexin-1 channel by probenecid attenuated SAH-induced AIM2 inflammasome activation and EBI in vivo and hemin-induced AIM2 inflammasome activation and neuronal death in vitro.

Managing Gout in Women: Current Perspectives

Gout is a common inflammatory arthritis that tends to affect significantly more men than women. However, female gout patients are more likely to have comorbidities such as hypertension, diabetes mellitus, and renal dysfunction. Furthermore, they experience a greater disease burden due to gout than males. While nonbiological causes may possibly contribute to this sex discrepancy in burden, this raises questions regarding whether current gout pharmacotherapies are as efficacious in females as they are in males. In this review, we examine how the clinical profile of female gout patients differs from male patients; we then survey the literature for data on outcomes for female gout patients treated with urate-lowering therapies for chronic management of gout as well as commonly used agents for acute flares. We also discuss considerations for managing gout in women during pregnancy and lactation.

Management of gout in chronic kidney disease: a G-CAN Consensus Statement on the research priorities

Gout and chronic kidney disease (CKD) frequently coexist, but quality evidence to guide gout management in people with CKD is lacking. Use of urate-lowering therapy (ULT) in the context of advanced CKD varies greatly, and professional bodies have issued conflicting recommendations regarding the treatment of gout in people with concomitant CKD. As a result, confusion exists among medical professionals about the appropriate management of people with gout and CKD. This Consensus Statement from the Gout, Hyperuricemia and Crystal-Associated Disease Network (G-CAN) discusses the evidence and/or lack thereof for the management of gout in people with CKD and identifies key areas for research to address the challenges faced in the management of gout and CKD. These discussions, which address areas for research both in general as well as related to specific medications used to treat gout flares or as ULT, are supported by separately published G-CAN systematic literature reviews. This Consensus Statement is not intended as a guideline for the management of gout in CKD; rather, it analyses the available literature on the safety and efficacy of drugs used in gout management to identify important gaps in knowledge and associated areas for research.

Efficacy and safety of urate-lowering therapy in people with kidney impairment: a GCAN-initiated literature review

OBJECTIVES

The aim was to evaluate the efficacy, defined as achieving target serum urate <6.0 mg/dl, and safety of urate-lowering therapies (ULTs) for people with gout and chronic kidney disease (CKD) stages 3-5.

METHODS

PubMed, The Cochrane Library and EMBASE were searched from 1 January 1959 to 31 January 2018 for studies that enrolled people with gout, who had an estimated glomerular filtration rate (eGFR) or creatinine clearance (CrCl) of <60 ml/min and exposure to allopurinol, febuxostat, probenecid, benzbromarone, lesinurad or pegloticase. All study designs other than case reports were included, except for people on dialysis, for whom we did include case reports.

RESULTS

There were 36 reports with an analysis of efficacy and/or safety based upon renal function: allopurinol (n = 12), febuxostat (n = 10), probenecid (n = 3), benzbromarone (n = 5), lesinurad (n = 5) and pegloticase (n = 1). There were 108 reports that involved people with gout and renal impairment but did not contain any analysis on efficacy and/or safety based upon renal function: allopurinol (n = 84), febuxostat (n = 14), benzbromarone (n = 1), lesinurad (n = 3) and pegloticase (n = 6). Most studies excluded people with more severe degrees of renal impairment (eGFR or CrCl of <30 ml/min). For allopurinol, in particular, there was significant variability in the dose of drug used and the efficacy in terms of urate lowering, across all levels of renal impairment.

CONCLUSION

There is a lack of evidence regarding the efficacy and/or safety of currently used ULTs according to different levels of renal function. Future studies should include patients with CKD and should report study outcomes stratified by renal function.

A 12-Week, Multicenter, Randomized, Double-Blind, Placebo-Controlled Clinical Trial for Evaluation of the Efficacy and Safety of DKB114 on Reduction of Uric Acid in Serum

This study sought to investigate the antihyperuricemia efficacy and safety of DKB114 (a mixture of Chrysanthemum indicum Linn flower extract and Cinnamomum cassia extract) to evaluate its potential as a dietary supplement ingredient. This clinical trial was a randomized, 12-week, double-blind, placebo-controlled study. A total of 80 subjects (40 subjects with an intake of DKB114 and 40 subjects with that of placebo) who had asymptomatic hyperuricemia (7.0–9.0 mg/dL with serum uric acid) was randomly assigned. No significant difference between the DKB114 and placebo groups was observed in the amount of uric acid in serum after six weeks of intake. However, after 12 weeks of intake, the uric acid level in serum of subjects in the DKB114 group decreased by 0.58 ± 0.86 mg/dL and was 7.37 ± 0.92 mg/dL, whereas that in the placebo group decreased by 0.02 ± 0.93 mg/dL and was 7.67 ± 0.89 mg/dL, a significant difference (p = 0.0229). In the analysis of C-reactive protein (CRP) change, after 12 weeks of administration, the DKB114 group showed an increase of 0.05 ± 0.27 mg/dL (p = 0.3187), while the placebo group showed an increase of 0.10 ± 0.21 mg/dL (p = 0.0324), a statistically significant difference (p = 0.0443). In the analysis of amount of change in apoprotein B, after 12 weeks of administration, the DKB114 group decreased by 4.75 ± 16.69 mg/dL (p = 0.1175), and the placebo group increased by 3.13 ± 12.64 mg/dL (p = 0.2187), a statistically significant difference between the administration groups (p = 0.0189). In the clinical pathology test, vital signs and weight measurement, and electrocardiogram test conducted for safety evaluation, no clinically significant difference was found between the ingestion groups, confirming the safety of DKB114. Therefore, it may have potential as a treatment for hyperuricemia and gout. We suggest that DKB114 as a beneficial and safe food ingredient for individuals with high serum uric acid. Trial registration (CRIS.NIH. go. Kr): KCT0002840.

Cost-effectiveness of sequential urate lowering therapies for the management of gout in Singapore

Aims: Allopurinol is the most common urate lowering therapy (ULT) used to treat gout but may cause life-threatening severe cutaneous adverse reactions (SCAR) in a small number of patients. Risk of SCAR is increased for patients with the HLA-B*58:01 genotype. When alternative ULT is required, febuxostat or probenecid are recommended. The aim of this study was to conduct a cost-utility analysis of sequential ULT treatment strategies for gout, including strategies with and without HLA-B*58:01 genotyping prior to treatment initiation, with a view to inform optimal gout management in Singapore.Materials and methods: A Markov model was developed from the Singapore healthcare payer perspective. Reflecting local practice, 12 different treatment strategies containing at least one ULT (allopurinol, febuxostat, probenecid) were evaluated in adults with gout. Response rates (SUA < 6mg/dL) were derived from an in-house network meta-analysis and from published literature. Incremental cost-effectiveness ratios (ICERs) were calculated over a 30-year time horizon, with costs and benefits discounted at 3% per annum. Sensitivity analyses were conducted to explore uncertainties.Results: Sequential treatment of allopurinol 300 mg/day-allopurinol 600 mg/day-probenecid ("standard of care") was cost-effective compared to no ULT, with an ICER of SGD1,584/QALY. Allopurinol300-allopurinol600-probenecid-febuxostat sequence compared to allopurinol300-allopurinol600-probenecid had an ICER of SGD11,400/QALY. All other treatment strategies were dominated by preceding strategies. Treatment strategies incorporating HLA-B*58:01 genotyping before ULT use were dominated by the corresponding non-genotyping strategy.Conclusions: Current standard of care (allopurinol300-allopurinol 600-probenecid) for gout is cost-effective compared with no ULT in the local context. Febuxostat is unlikely to be cost-effective in Singapore at current prices unless it is used last-line.

Is HLA-B*58:01 genotyping cost effective in guiding allopurinol use in gout patients with chronic kidney disease?

Aim: Concerns for fatal severe cutaneous adverse reactions (SCARs) hamper allopurinol use. Methods and material: We adopted a health system perspective to evaluate the cost-effectiveness of HLA-B*58:01 genotyping before allopurinol initiation. A decision tree compared three treatment strategies in gout patients with chronic kidney disease who have higher risk for SCAR. They were standard allopurinol treatment followed by febuxostat in nonresponders, test-positive patients receive febuxostat while test-negative receive allopurinol and universal use of febuxostat. Results: The first strategy was the most cost effective. Genotyping dominated universal febuxostat use. Time horizon and SCAR incidence were the most influential factors on the incremental cost-effectiveness ratio. Conclusion: HLA-B*58:01 genotyping compared with standard allopurinol-febuxostat sequential treatment does not provide good value for money in gout with chronic kidney disease.

Hyperuricemia and Cardiovascular Disease

Purine metabolism in the circulatory system yields uric acid as its final oxidation product, which is believed to be linked to the development of gout and kidney stones. Hyperuricemia is closely correlated with cardiovascular disease, metabolic syndrome, and chronic kidney disease, as attested by the epidemiological and empirical research. In this review, we summarize the recent knowledge about hyperuricemia, with a special focus on its physiology, epidemiology, and correlation with cardiovascular disease. This review also discusses the possible positive effects of treatment to reduce urate levels in patients with cardiovascular disease and hyperuricemia, which may lead to an improved clinical treatment plan.

Variation in methods, results and reporting in electronic health record-based studies evaluating routine care in gout: A systematic review

OBJECTIVE

To perform a systematic review examining the variation in methods, results, reporting and risk of bias in electronic health record (EHR)-based studies evaluating management of a common musculoskeletal disease, gout.

METHODS

Two reviewers systematically searched MEDLINE, Scopus, Web of Science, CINAHL, PubMed, EMBASE and Google Scholar for all EHR-based studies published by February 2019 investigating gout pharmacological treatment. Information was extracted on study design, eligibility criteria, definitions, medication usage, effectiveness and safety data, comprehensiveness of reporting (RECORD), and Cochrane risk of bias (registered PROSPERO CRD42017065195).

RESULTS

We screened 5,603 titles/abstracts, 613 full-texts and selected 75 studies including 1.9M gout patients. Gout diagnosis was defined in 26 ways across the studies, most commonly using a single diagnostic code (n = 31, 41.3%). 48.4% did not specify a disease-free period before 'incident' diagnosis. Medication use was suboptimal and varied with disease definition while results regarding effectiveness and safety were broadly similar across studies despite variability in inclusion criteria. Comprehensiveness of reporting was variable, ranging from 73% (55/75) appropriately discussing the limitations of EHR data use, to 5% (4/75) reporting on key data cleaning steps. Risk of bias was generally low.

CONCLUSION

The wide variation in case definitions and medication-related analysis among EHR-based studies has implications for reported medication use. This is amplified by variable reporting comprehensiveness and the limited consideration of EHR-relevant biases (e.g. data adequacy) in study assessment tools. We recommend accounting for these biases and performing a sensitivity analysis on case definitions, and suggest changes to assessment tools to foster this.

Making the right thing the easy thing to do: strategies to improve outcomes in gout

The burden of gout is increasing worldwide. Although urate-lower ing drugs have been available for more than half a century, the initiation and persistence of urate-lowering therapy remain low. Health-care system, practitioner, and patient barriers contribute to the clinical inertia in gout management. Pervasive beliefs about gout as a disease of an indulgent lifestyle that should be managed primarily with dietary modification are key barriers that prevent patients from receiving effective therapy. In light of safety concerns about newer urate-lowering medications, allopurinol, an inexpensive generic medication, is likely to remain the first-line urate-lowering therapy for the foreseeable future. Ensuring that allopurinol is optimally and persistently prescribed is a priority for improved gout management. A health literacy approach that focuses on patient understanding of gout as a chronic disease that requires behaviour change to take long term urate-lowering therapy is important. This approach provides a clear rationale for long-term urate-lowering therapy that is able to dissolve the monosodium urate crystals and ultimately prevent the symptoms of gout. Patient-centred models that use the skills of nurses and pharmacists to facilitate patient understanding can lead to major improvements in gout care. Additionally, systematic quality improvement approaches within practices, while reducing inconvenience and cost to patients, should be a priority.

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.

Safety and tolerability of available urate-lowering drugs: a critical review

INTRODUCTION

Urate-lowering therapy (ULT) is the cornerstone of gout management, which is a widespread chronic illness characterized by hyperuricemia, arthropathy, tophus development, and urolithiasis. Since asymptomatic increased serum urate levels are associated with a higher risk of cardiovascular, renal and metabolic disorders, a larger use of ULTs in the general population is expected in the near future.

AREAS COVERED

This review will focus on the safety and tolerability profile of the available urate-lowering drugs: xanthine oxidase inhibitors (XOIs), uricosuric agents and injectable uricases.

EXPERT OPINION

Older drugs for ULT like allopurinol are well studied and extensively described from typical adverse effects (mild skin rash) to unusual fatal reactions, while febuxostat seems to be overall well tolerated. More evidence is required to define the safety profile of topiroxostat, arhalofenate, tranilast, and sulfinpyrazone. Furthermore, there are some unanswered questions about the pharmacological interactions of probenecid and the hepatotoxicity of benzbromarone. Despite a limited use in clinical practice, combination therapy with lesinurad or verinurad and XOI is not frequently accompanied by side effects. Rasburicase and pegloticase are usually well tolerated with some specific exceptions. Before prescribing UL drugs, physicians should take into account their safety profile tailoring the treatment on the patient characteristics.

Gout - An update of aetiology, genetics, co-morbidities and management

Gout is an increasingly common chronic disorder of urate crystal deposition that manifests as flares of acute inflammatory arthritis. Hyperuricaemia is a prerequisite and a fifth of both men and woman are hyperuricaemic. The prevalence of gout is much lower than the prevalence of hyperuricaemia for reasons that are not currently clear. Gout is more common in men than women prior to menopause due to the uricosuric effects of oestrogen, but after menopause the incidence of gout rises substantially in women. Co-morbidities are an important issue in gout, with cardiovascular disease, diabetes mellitus, obesity and chronic kidney disease all common in patients with gout. Environmental factors like diet affect the incidence of gout but there is little evidence to support an emphasis on diet in treating established gout. The diagnosis of gout is often made without the use of joint aspiration and validated diagnostic rules are available for both primary and secondary care as well as classification criteria for research use. The overarching principle of the management of gout with pharmacotherapy is the need to reduce serum urate levels to below a target of 0.30 mmol/L or 0.36 mmol/L depending on whether it is tophaceous or non-tophaceous respectively. The use of allopurinol has been researched extensively and newer strategies for safer effective dosing are now recommended. Newer agents have been introduced for the treatment of gout, including febuxostat and lesinurad. A number of important questions in the field are under current investigation.

Febuxostat for the treatment of hyperuricaemia in gout

INTRODUCTION

Febuxostat is a potent non-purine selective xanthine oxidase inhibitor approved by the FDA in 2009 for management of hyperuricemia in people with gout. Areas covered: The authors summarize the pre-clinical studies and pivotal randomized controlled trials of febuxostat when used as a treatment for hyperuricaemia in gout Expert opinion: Febuxostat has clinical efficacy in serum urate lowering, and long-term use leads to improved outcomes such as gout flare frequency and tophus burden. Recently published post-approval placebo-controlled trials have demonstrated urate-lowering efficacy and safety of febuxostat in patients with chronic kidney disease, and reduced frequency of gout flares in people with early onset of gout. In November 2017, the FDA issued a drug safety communication based on the preliminary results of the CARES trial. This cardiovascular safety study of 6190 patients with gout and established cardiovascular disease comparing febuxostat and allopurinol showed no difference in the primary endpoint (a composite of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, or unstable angina with urgent revascularization), but did report higher all-cause mortality (hazard ratio 1.22) and cardiovascular mortality (hazard ratio 1.34) with febuxostat. Based on currently available data, it seems likely that allopurinol, rather than febuxostat, will remain first line urate-lowering therapy for people with gout.

Recent pharmacological advances in the management of gout

Gout is the most common cause of inflammatory arthritis worldwide, and reports show that despite availability of therapies, management is still suboptimal. The new EULAR 2016 recommendations for the treatment of gout highlight the huge development in gout therapies, and the number of drugs being trialled only continues to increase. A clinical review of the evidence that underlies the recommendations from EULAR can reveal possible gaps in the literature and avenues for future research into gout therapies.

Physiology of Hyperuricemia and Urate-Lowering Treatments

Gout is the most common form of inflammatory arthritis and is a multifactorial disease typically characterized by hyperuricemia and monosodium urate crystal deposition predominantly in, but not limited to, the joints and the urinary tract. The prevalence of gout and hyperuricemia has increased in developed countries over the past two decades and research into the area has become progressively more active. We review the current field of knowledge with emphasis on active areas of hyperuricemia research including the underlying physiology, genetics and epidemiology, with a focus on studies which suggest association of hyperuricemia with common comorbidities including cardiovascular disease, renal insufficiency, metabolic syndrome and diabetes. Finally, we discuss current therapies and emerging drug discovery efforts aimed at delivering an optimized clinical treatment strategy.

Gout: An old disease in new perspective - A review

Gout is a picturesque presentation of uric acid disturbance. It is the most well understood and described type of arthritis. Its epidemiology is studied. New insights into the pathophysiology of hyperuricemia and gouty arthritis; acute and chronic allow for an even better understanding of the disease. The role of genetic predisposition is becoming more evident. The clinical picture of gout is divided into asymptomatic hyperuricemia, acute gouty arthritis, intercritical period, and chronic tophaceous gout. Diagnosis is based on laboratory and radiological features. The gold standard of diagnosis is identification of characteristic MSU crystals in the synovial fluid using polarized light microscopy. Imaging modalities include conventional radiography, ultrasonography, conventional CT, Dual-Energy CT, Magnetic Resonance Imaging, nuclear scintigraphy, and positron emission tomography. There is remarkable progress in the application of ultrasonography and Dual-Energy CT which is bound to influence the diagnosis, staging, follow-up, and clinical research in the field. Management of gout includes management of flares, chronic gout and prevention of flares, as well as management of comorbidities. Newer drugs in the pharmacological armamentarium are proving successful and supplement older ones. Other important points in its management include patient education, diet and life style changes, as well as cessation of hyperuricemic drugs.

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.

Treatment of hyperuricemia in gout: current therapeutic options, latest developments and clinical implications

Despite being the most common type of inflammatory arthritis, gout is often poorly managed. Except for febuxostat and pegloticase, research in new therapeutic agents for the management of hyperuricemia in gout remained insufficient for several decades. With emerging evidence of possible roles of hyperuricemia in cardiometabolic comorbidities, as well as more convincing evidence regarding poor outcomes (e.g. disability, recurrent hospital admissions) in patients with uncontrolled gout, several agents are current under development. Increasing knowledge regarding renal urate transporters has resulted in the development of new generation uricosurics such as lesinurad and arhalofenate. This review aims at discussing current therapeutic strategies for gout, as well as their limitations and the possible role of emerging agents in the chronic management of hyperuricemia in gout. Drugs in phases I and II of development will be discussed, along with new agents and therapeutic classes, such as purine nucleoside phosphorylase inhibitors and dual-action drugs. These new developments are encouraging, and will hopefully contribute to a more adequate management of hyperuricemia in gout.

2016 updated EULAR evidence-based recommendations for the management of gout

Background

New drugs and new evidence concerning the use of established treatments have become available since the publication of the first European League Against Rheumatism (EULAR) recommendations for the management of gout, in 2006. This situation has prompted a systematic review and update of the 2006 recommendations.

Methods

The EULAR task force consisted of 15 rheumatologists, 1 radiologist, 2 general practitioners, 1 research fellow, 2 patients and 3 experts in epidemiology/methodology from 12 European countries. A systematic review of the literature concerning all aspects of gout treatments was performed. Subsequently, recommendations were formulated by use of a Delphi consensus approach.

Results

Three overarching principles and 11 key recommendations were generated. For the treatment of flare, colchicine, non-steroidal anti-inflammatory drugs (NSAIDs), oral or intra-articular steroids or a combination are recommended. In patients with frequent flare and contraindications to colchicine, NSAIDs and corticosteroids, an interleukin-1 blocker should be considered. In addition to education and a non-pharmacological management approach, urate-lowering therapy (ULT) should be considered from the first presentation of the disease, and serum uric acid (SUA) levels should be maintained at<6 mg/dL (360 µmol/L) and <5 mg/dL (300 µmol/L) in those with severe gout. Allopurinol is recommended as first-line ULT and its dosage should be adjusted according to renal function. If the SUA target cannot be achieved with allopurinol, then febuxostat, a uricosuric or combining a xanthine oxidase inhibitor with a uricosuric should be considered. For patients with refractory gout, pegloticase is recommended.

Conclusions

These recommendations aim to inform physicians and patients about the non-pharmacological and pharmacological treatments for gout and to provide the best strategies to achieve the predefined urate target to cure the disease.

Gout Is a Chronic Inflammatory Disease in Which High Levels of Interleukin-8 (CXCL8), Myeloid-Related Protein 8/Myeloid-Related Protein 14 Complex, and an Altered Proteome Are Associated With Diabetes Mellitus and Cardiovascular Disease

OBJECTIVE

The frequent association of gout with metabolic syndrome and cardiovascular disease (CVD) suggests that it has a systemic component. Our objective was to study whether circulating proinflammatory cytokines are associated with comorbidities in gout patients.

METHODS

We studied 330 gout patients from 3 independent cohorts and compared them with 144 healthy individuals and 276 disease controls. We measured circulating levels of interleukin-8 (IL-8)/CXCL8, IL-1β, IL-6, IL-10, IL-12, and tumor necrosis factor, after which we performed proteome-wide analysis in a selection of samples to identify proteins that were possibly prognostic for the development of comorbidities. Replication analysis was performed specifically for myeloid-related protein 8 (MRP-8)/MRP-14 complex.

RESULTS

Compared to healthy controls and disease control patients, patients with gouty arthritis (n = 48) had significantly higher mean levels of CXCL8 (P < 0.001), while other cytokines were almost undetectable. Similarly, patients with intercritical gout showed high levels of CXCL8. CXCL8 was independently associated with diabetes mellitus in patients with intercritical gout (P < 0.0001). Proteome-wide analysis in gouty arthritis (n = 18) and intercritical gout (n = 39) revealed MRP-8 and MRP-14 as the proteins with the greatest differential expression between low and high levels of CXCL8 and also showed a positive correlation of MRP8/MRP14 complex with CXCL8 levels (R(2)  = 0.49, P < 0.001). These findings were replicated in an independent cohort. The proteome of gout patients with high levels of CXCL8 was associated with diabetes mellitus (odds ratio 16.5 [95% confidence interval 2.8-96.6]) and CVD (odds ratio 3.9 [95% confidence interval 1.0-15.3]).

CONCLUSION

Circulating levels of CXCL8 are increased during both the acute and intercritical phases of gout, and they coincide with a specific circulating proteome that is associated with risk of diabetes mellitus and CVD. Further research focused on the roles of CXCL8 and MRP8/MRP14 complex in patients with gout is warranted.

Cost-effectiveness analysis of genotyping for HLA-B*5801 and an enhanced safety program in gout patients starting allopurinol in Singapore

AIMS

Allopurinol is an efficacious urate-lowering therapy (ULT), but is associated with rare serious adverse drug reactions of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), with higher risk among HLA-B*5801 carriers. We assessed the cost-effectiveness of HLA-B*5801 testing, an enhanced safety program or strategies with both components.

METHODS

The analysis adopted a health systems perspective and considered Singaporean patients with chronic gout, over a lifetime horizon, using allopurinol or probenecid. The model incorporated SJS/TEN and gout treatment outcomes, allele frequencies, drug prices and other medical costs.

RESULTS

Based on cost-effectiveness threshold of US$50,000 per quality-adjusted life year, HLA-B*5801-guided ULT selection or enhanced safety program was not cost effective. Avoidance of ULTs was the least preferred strategy as uncontrolled gout leads to lower quality-adjusted life years and higher costs.

CONCLUSION

The analysis underscores the need for biomarkers with higher positive predictive value for SJS/TEN, less expensive genetic tests or safety programs, or more effective gout drugs. .

Effects of rifampin, cyclosporine A, and probenecid on the pharmacokinetic profile of canagliflozin, a sodium glucose co-transporter 2 inhibitor, in healthy participants

OBJECTIVE

Canagliflozin, a sodium-glucose co-transporter 2 inhibitor, approved for the treatment of type-2 diabetes mellitus (T2DM), is metabolized by uridine diphosphate-glucuronosyltransferases (UGT) 1A9 and UGT2B4, and is a substrate of P-glycoprotein (P-gp). Canagliflozin exposures may be affected by coadministration of drugs that induce (e.g., rifampin for UGT) or inhibit (e.g. probenecid for UGT; cyclosporine A for P-gp) these pathways. The primary objective of these three independent studies (single-center, open-label, fixed-sequence) was to evaluate the effects of rifampin (study 1), probenecid (study 2), and cyclosporine A (study 3) on the pharmacokinetics of canagliflozin in healthy participants.

METHODS

Participants received; in study 1: canagliflozin 300 mg (days 1 and 10), rifampin 600 mg (days 4-12); study 2: canagliflozin 300 mg (days 1-17), probenecid 500 mg twice daily (days 15-17); and study 3: canagliflozin 300 mg (days 1-8), cyclosporine A 400 mg (day 8). Pharmacokinetics were assessed at prespecified intervals on days 1 and 10 (study 1); on days 14 and 17 (study 2), and on days 2-8 (study 3).

RESULTS

Rifampin decreased the maximum plasma canagliflozin concentration (Cmax) by 28% and its area under the curve (AUC) by 51%. Probenecid increased the Cmax by 13% and the AUC by 21%. Cyclosporine A increased the AUC by 23% but did not affect the Cmax.

CONCLUSION

Coadministration of canagliflozin with rifampin, probenecid, and cyclosporine A was well-tolerated. No clinically meaningful interactions were observed for probenecid or cyclosporine A, while rifampin coadministration modestly reduced canagliflozin plasma concentrations and could necessitate an appropriate monitoring of glycemic control.

Urate-lowering therapy: current options and future prospects for elderly patients with gout

Gout is increasingly seen in the elderly population, in large part due to physiological decline in renal function with age, and as a result of therapy for comorbidities, in particular the use of diuretic therapies for hypertension and congestive heart failure. Urate-lowering therapy (ULT) is the cornerstone of successful long-term gout management with the aim of achieving a sustained reduction in urate (<0.36 mmol/L, or lower [<0.30 mmol/L] in those with tophi). After decades during which there has been relatively little interest in developing new agents to treat gout, the last 5-10 years has seen a plethora of new agents with several now used in routine clinical practice. There has also been a renewed focus on the optimal use of established ULT, specifically allopurinol, which remains the first-line therapy for most patients. There is emerging data on its use in patients with renal impairment and better recognition of risk factors of the rare but potentially lethal allopurinol hypersensitivity syndrome (AHS). Febuxostat, a new xanthine oxidase inhibitor, is now established in everyday practice. Uricosuric agents may be indicated in certain patient groups, whilst a new class of recombinant uricases (pegloticase) given by intravenous infusion may achieve dramatic and rapid urate-lowering effects. Cost and other factors have thus far limited its use to the very severe cases. Furthermore, increased understanding of urate metabolism has led to the development of a number of drugs currently under clinical evaluation. Common therapeutic targets are the urate transporters in the kidney and alternative xanthine oxidase inhibition pathways. These advances bode well for the better management of gout and hyperuricaemia in our elderly patients.

Gout: A clinical overview and its association with cardiovascular diseases

Gout is a common disease caused by the deposition of monosodium urate (MSU) crystals in patients with hyperuricemia, and characterized by very painful recurrent acute attacks of arthritis. The gold standard for diagnosing gout is the identification of MSU crystals in synovial fluid by polarization light microscopy. Arthritis attacks can be treated with anti-inflammatory medications, such as non-steroidal anti-inflammatory drugs, colchicine, oral prednisone, or intra-articular or intramuscular glucocorticoids. To prevent gout uric acid lowering therapy with for example allopurinol can be prescribed. When gout is adequately treated, the prognosis is good. Unfortunately, the management of gout patients is often insufficient. Gout is associated with dietary factors, the use of diuretics, and several genetic factors. Comorbidities as hypertension, chronic kidney disease, cardiovascular diseases, the metabolic syndrome, diabetes, obesity, hyperlipidemia, and early menopause are associated with a higher prevalence of gout. Xanthine oxidase and chronic systemic inflammation seem to play an important role in the pathophysiology of the association between gout and cardiovascular diseases. To prevent cardiovascular diseases gout patients must be early screened for cardiovascular risk factors.

Gout: joints and beyond, epidemiology, clinical features, treatment and co-morbidities

Gout is a common inflammatory arthritis precipitated by an inflammatory reaction to urate crystals in the joint. Gout is increasingly being recognised as a disease primarily of urate overload with arthritis being a consequence of this pathological accumulation. It is associated with a number of important co-morbidities including chronic kidney disease, obesity, diabetes and cardiovascular disease. The prevalence of gout is increasing around the world. Significant progress has been made in determining the genetic basis for both gout and hyperuricaemia. Environmental risk factors for gout have been identified as certain foods, alcohol and several medications. There is, however, little evidence that changing these environmental risks improves gout on an individual level. Treatment of gout encompasses two strategies: firstly treatment of inflammatory arthritis with non-steroidal anti-inflammatories, corticosteroids, colchicine or interleukin-1 inhibitors. The second and most important strategy is urate lowering, to a target of 0.36 mmol/L (6 mg/dL) or potentially lower in those with tophi (collections of crystalline urate subcutaneously). Along with urate lowering, adequate and prolonged gout flare prophylaxis is required to prevent the precipitation of acute attacks. Newer urate lowering agents are in development and have the potential to significantly expand the potential treatment options. Education of patients regarding the importance of life long urate lowering therapy and prophylaxis of acute attacks is critical to treatment success as adherence with medication is low in chronic diseases in general but especially in gout.

Impaired response or insufficient dosage? Examining the potential causes of "inadequate response" to allopurinol in the treatment of gout

OBJECTIVES

Gout is one of the most common forms of arthritis. It is well established that urate-lowering therapy that aims for a serum urate less than at least 0.36 mmol/l (6 mg/dl) is required for the successful management of gout. Allopurinol, a xanthine oxidase (XO) inhibitor, is the most commonly used urate-lowering therapy. However, many patients fail to achieve the target serum urate on allopurinol; these patients can be considered to have "inadequate response" to allopurinol. Herein, we examine the potential mechanisms and implications of inadequate response to allopurinol.

METHODS

The literature was reviewed for potential causes for failure to reach target serum urate in patients receiving allopurinol.

RESULTS

The two most common causes of inadequate response to allopurinol are poor adherence and under-dosing of allopurinol. Adherent patients who fail to achieve target serum urate on standard doses of allopurinol form a group that could be considered to be "partially resistant" to allopurinol. There are four potential mechanisms for partial allopurinol resistance: decreased conversion of allopurinol to oxypurinol; increased renal excretion of oxypurinol; abnormality in XO structure and/or function such that oxypurinol is rendered less effective and/or drug interactions.

CONCLUSIONS

It is important to determine the reasons for failure to achieve treatment targets with allopurinol, particularly as newer agents become available. The knowledge of the mechanisms for inadequate response may help guide the clinician towards making a therapeutic choice that is more likely to result in achieving the serum urate target.

Probenecid protects against transient focal cerebral ischemic injury by inhibiting HMGB1 release and attenuating AQP4 expression in mice

Stroke results in inflammation, brain edema, and neuronal death. However, effective neuroprotectants are not available. Recent studies have shown that high mobility group box-1 (HMGB1), a proinflammatory cytokine, contributes to ischemic brain injury. Aquaporin 4 (AQP4), a water channel protein, is considered to play a pivotal role in ischemia-induced brain edema. More recently, studies have shown that pannexin 1 channels are involved in cerebral ischemic injury and the cellular inflammatory response. Here, we examined whether the pannexin 1 channel inhibitor probenecid could reduce focal ischemic brain injury by inhibiting cerebral inflammation and edema. Transient focal ischemia was induced in C57BL/6J mice by middle cerebral artery occlusion (MCAO) for 1 h. Infarct volume, neurological score and cerebral water content were evaluated 48 h after MCAO. Immunostaining, western blot analysis and ELISA were used to assess the effects of probenecid on the cellular inflammatory response, HMGB1 release and AQP4 expression. Administration of probenecid reduced infarct size, decreased cerebral water content, inhibited neuronal death, and reduced inflammation in the brain 48 h after stroke. In addition, HMGB1 release from neurons was significantly diminished and serum HMGB1 levels were substantially reduced following probenecid treatment. Moreover, AQP4 protein expression was downregulated in the cortical penumbra following post-stroke treatment with probenecid. These results suggest that probenecid, a powerful pannexin 1 channel inhibitor, protects against ischemic brain injury by inhibiting cerebral inflammation and edema.