Allopurinol for chronic gout

Stevens-Johnson Syndrome From Combined Allopurinol and Angiotensin-Converting Enzyme Inhibitors: A Narrative Review

Stevens-Johnson syndrome (SJS) is a severe and potentially debilitating skin reaction frequently related to medication use. Allopurinol and angiotensin-converting enzyme (ACE) inhibitors are commonly prescribed medications for prevalent health conditions worldwide, and their interaction associated with SJS warrants further investigation. A comprehensive literature search was performed to investigate cases as studies related to SJS occurring in patients with concomitant use of allopurinol and ACE inhibitors. We identified case reports and studies detailing hypersensitivity reactions, including SJS, attributed to a combination of allopurinol and ACE inhibitors. Despite the drug-drug interactions or lack thereof seen in patient populations, there is no definitive evidence of a pharmacokinetic interaction between allopurinol and ACE inhibitors. We were only able to find one case report specifically detailing SJS in a patient on combined ACE inhibitors and allopurinol. While the exact mechanism of the interaction is unclear, those reported cases of severe hypersensitivity reactions suggest a previous history of impaired renal function as a predisposing factor in the development of SJS. The potential risk of SJS with coadministration of ACE inhibitors and allopurinol is a drug-drug interaction that physicians should be aware of. This topic requires additional attention to determine if this drug combination should be avoided entirely in certain patients.

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.

Anti-Inflammatory Therapy in Coronary Artery Disease: Where Do We Stand?

Inflammation plays an important role in all stages of atherosclerosis - from endothelial dysfunction, to formation of fatty streaks and atherosclerotic plaque, and its progression to serious complications, such as atherosclerotic plaque rupture. Although dyslipidemia is a key driver of atherosclerosis, pathogenesis of atherosclerosis is now considered interplay between cholesterol and inflammation, with the significant role of the immune system and immune cells. Despite modern therapeutic approaches in primary and secondary cardiovascular prevention, cardiovascular diseases remain the leading cause of mortality worldwide. In order to reduce residual cardiovascular risk, despite the guidelines-guided optimal medical therapy, novel therapeutic strategies are needed for prevention and management of coronary artery disease. One of the innovative and promising approaches in atherosclerotic cardiovascular disease might be inflammation-targeted therapy. Numerous experimental and clinical studies are seeking into metabolic pathways underlying atherosclerosis, in order to find the most suitable pathway and inflammatory marker/s that should be the target for anti-inflammatory therapy. Many anti-inflammatory drugs have been tested, from the well-known broad range anti-inflammatory agents, such as colchicine, allopurinol and methotrexate, to targeted monoclonal antibodies specifically inhibiting a molecule included in inflammatory pathway, such as canakinumab and tocilizumab. To date, there are no approved anti-inflammatory agents specifically indicated for silencing inflammation in patients with coronary artery disease. The most promising results came from the studies which tested colchicine, and studies where the inflammatory-target was NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome/interleukin-1 beta (IL-1 β )/interleukin-6 (IL-6)/C-reactive protein (CRP) pathway. A growing body of evidence, along with the ongoing clinical studies, suggest that the anti-inflammatory therapy might become an additional strategy in treating atherosclerotic cardiovascular disease. Herein we present an overview of the role of inflammation in atherosclerosis, the most important inflammatory markers chosen as targets of anti-inflammatory therapy, along with the critical review of the major clinical trials which tested non-targeted and targeted anti-inflammatory drugs in patients with atherosclerotic cardiovascular disease.

Multifaced Assessment of Antioxidant Power, Phytochemical Metabolomics, In-Vitro Biological Potential and In-Silico Studies of Neurada procumbens L.: An Important Medicinal Plant

This work was undertaken to explore the phytochemical composition, antioxidant, and enzyme-inhibiting properties of Neurada procumbens L. extracts/fractions of varying polarity (methanol extract and its fractions including n-hexane, chloroform, n-butanol, and aqueous fractions). A preliminary phytochemical study of all extracts/fractions, HPLC-PDA polyphenolic quantification, and GC-MS analysis of the n-hexane fraction were used to identify the phytochemical makeup. Antioxidant (DPPH), enzyme inhibition (against xanthine oxidase, carbonic anhydrase, and urease enzymes), and antibacterial activities against seven bacterial strains were performed for biological investigation. The GC-MS analysis revealed the tentative identification of 22 distinct phytochemicals in the n-hexane fraction, the majority of which belonged to the phenol, flavonoid, sesquiterpenoid, terpene, fatty acid, sterol, and triterpenoid classes of secondary metabolites. HPLC-PDA analysis quantified syringic acid, 3-OH benzoic acid, t-ferullic acid, naringin, and epicatechin in a significant amount. All of the studied extracts/fractions displayed significant antioxidant capability, with methanol extract exhibiting the highest radical-scavenging activity, as measured by an inhibitory percentage of 81.4 ± 0.7 and an IC₅₀ value of 1.3 ± 0.3. For enzyme inhibition experiments, the n-hexane fraction was shown to be highly potent against xanthine oxidase and urease enzymes, with respective IC₅₀ values of 2.3 ± 0.5 and 1.1 ± 0.4 mg/mL. Similarly, the methanol extract demonstrated the strongest activity against the carbonic anhydrase enzyme, with an IC₅₀ value of 2.2 ± 0.4 mg/mL. Moreover, all the studied extracts/fractions presented moderate antibacterial potential against seven bacterial strains. Molecular docking of the five molecules β-amyrin, campesterol, ergosta-4,6,22-trien-3β-ol, stigmasterol, and caryophyllene revealed the interaction of these ligands with the investigated enzyme (xanthine oxidase). The results of the present study suggested that the N. procumbens plant may be evaluated as a possible source of bioactive compounds with multifunctional therapeutic applications.

Phenolic Compound in Garlic (Allium sativum) and Black Garlic Potency as Antigout Using Molecular Docking Approach

Phenolics, including flavonoids, are bioactive components in garlic in relatively abundant amounts and are present 2–4 times more in black garlic. Both of these compounds are reported to have biological activity, with one of them acting as an antioxidant. However, its ability as an antigout is still not widely reported. Xanthine oxidase, adenine deaminase, guanine deaminase, purine nucleoside phosphorylase, and 5-Nucleotidase II are involved during the production of uric acid and causes gout. This study predicted the potential of the phenolic and flavonoid compounds in garlic and black garlic as antigout in inhibiting five target receptors through a molecular docking approach. Utilizing AutoDock Tools v.1.5.7 for receptor and ligand preparation, AutoDock Vina and AutoDock4 for molecular docking, and LigPlot+ and PyMOL for visualization. About 21 compounds from the phenolic and flavonoid groups were used as test ligands and 16 reference ligands (substrate and commercial). SwissADME predicted the pharmacokinetic parameters. The results showed that apigenin, morin, resveratrol, kaempferol, (+)-catechin, isorhamnetin, and (-)-epicatechin were predicted to have good interactions at each target receptor and had the potential to be developed as candidates for multi-target antigout. Based on the pharmacokinetic parameters, all these compounds had good scores in each, making them feasible to continue in vitro or in vivo trials.

Bioactive Compounds in Garlic (Allium sativum) and Black Garlic as Antigout Agents, Using Computer Simulation

Uric acid, which causes gout, is the end product of purine catabolism, synthesized by xanthine oxidase, guanine deaminase, adenine deaminase, purine nucleoside phosphorylase, and 5-nucleotidase II. Garlic contains bioactive compounds that have potential as antigout agents. Garlic fermentation to black garlic changes its components, which may affect its beneficial potential. This study aimed to select types of garlic (Indonesian garlic) and imported garlic, and to predict the interaction between their compounds and five target proteins through an in silico approach and a multivariate analysis, namely partial least squares-discriminant analysis (PLS-DA), to determine their different constituents. The target proteins were collected from open-access databases, and the compounds were identified using mass spectrometry data. The PLS-DA score plot succeeded in classifying the samples into three classes, with each class having a discriminatory compound. Based on the in silico studies, we predicted the best binding score of the five target proteins with seven important compounds: alliin, N-acetyl-S-allyl-L-cysteine, ajoene, pyridoxal, pyridoxamine, 4-guanidinobutyric acid, and D-glucosamine. These were mostly found in black garlic, with no different concentrations in the local and imported samples. Through this approach, we concluded that black garlic is a better candidate for antigout treatments, as several compounds were found to have good binding to the target proteins.

Acylation of Anthocyanins and Their Applications in the Food Industry: Mechanisms and Recent Research Advances

Anthocyanins are extensively used as natural non-toxic compounds in the food industry due to their unique biological properties. However, the instability of anthocyanins greatly affects their industrial application. Studies related to acylated anthocyanins with higher stability and increased solubility in organic solvents have shown that the acylation of anthocyanins can improve the stability and fat solubility of anthocyanins. However, relevant developments in research regarding the mechanisms of acylation and applications of acylated anthocyanins are scarcely reviewed. This review aims to provide an overview of the mechanisms of acylation and the applications of acylated anthocyanins in the food industry. In the review, acylation methods, including biosynthesis, semi-biosynthesis, and chemical and enzymatic acylation, are elaborated, physicochemical properties and biological activities of acylated anthocyanins are highlighted, and their application as colourants, functionalizing agents, intelligent indicators, and novel packaging materials in the food industry are summarized. The limitations encountered in the preparation of acylated anthocyanins and future prospects, their applications are also presented. Acylated anthocyanins present potential alternatives to anthocyanins in the food industry due to their functions and advantages as compared with non-acylated analogues. It is hoped that this review will offer further information on the effective synthesis and encourage commercialization of acylated anthocyanins in the food industry.

Inhibitory effects of Moringa oleifera leaves extract on xanthine oxidase activity from bovine milk

Moringa oleifera is a tropical plant in the Moringaceae family that contains a lot of bioactive compounds. This study aimed to isolate and characterize the enzyme xanthine oxidase (XO), and conducted inhibitory tests on XO using methanol extracts of M. oleifera leaves. The xanthine oxidase enzyme isolated from bovine milk was characterized to determine the optimum pH, temperature, and substrate concentration. XO inhibition was evaluated by in vitro and in silico methods. The results of XO isolation and characterization of bovine milk showed the optimum conditions at pH 6.5, substrate concentration of 0.1 mM, and temperature 35 °C with an activity rate of 32.47 mU/mL; 21.55 mU/mL, and 21.94 mU/mL. Inhibition analysis results on methanol extract of M. oleifera leaves showed the highest activity decrease at the extract concentration of 160 ppm, with a relative inhibition value of 21.35%, while allopurinol as a positive control has a relative value inhibition of 61.21%. Relative value inhibition indicated the potential of M. oleifera leaves as a source of medicinal plants for gout sufferers. Additionally, a computational analysis was performed to observe the molecular interaction between the primary compounds of M. oleifera leaves, i.e., 5-O-acetyl-thio-octyl-β-L-rhamnofuranoside, quinic acid, and 2-dimethyl(trimethylsilylmethyl)silyloxymethyltetrahydrofuran, and XO using the molecular docking method. The finding implied that these compounds are bound to the catalytic sites of XO by hydrogen bonds and hydrophobic interactions, indicating the primary compounds of M. oleifera leaves could become XO inhibitors to treat gout disease.

Management of gout in the primary care setting

Gout is a commonly treated inflammatory arthritis that is often managed in the primary care setting. This disease is prevalent among the multi-ethnic Malaysian population. Unfortunately, gout is still frequently managed sub-optimally, even in the hospital and primary care settings. Gout should be considered a major disease since it can potentially lead to multiple disabilities from joint destruction, nephropathy and increased cardiovascular morbidity and mortality. The objectives of this review are to summarise the latest updated information and management of gout in the primary care setting.

Development of a patient decision aid for the initiation of urate-lowering therapy in gout patients

Aim

Shared decision-making improves patients’ experiences with care, satisfaction with management decisions and possibly health outcomes. This study describes the development of a decision aid (DA) that supports patients with gout and their physicians in a face-to-face clinical setting to (a) decide whether or not to (re)start urate-lowering therapy (ULT) and (b) agree on the preferred ULT.

Methods

Recommendations of the International Patient Decision Aid Standards group guided the development. A steering group of experts in gout and health services research specified the scope. Nominal group technique meetings were organised in which patients ranked the importance of preidentified potential characteristics/attributes of ULT and discussed further needs regarding the DA. A literature search was conducted to collect evidence on gout outcomes with and without ULT. Subsequently, the DA prototype was designed and adjusted using feedback from the steering group and results of cognitive debriefing interviews among five gout patients.

Results

The final DA consists of six pages. First, the DA clarifies the decision at stake and describes gout including its risk factors, the role of lifestyle and treatment of flares. Next, risk of future flares with and without ULT in relation to serum uric acid levels is described and visualised. Relevant attributes of ULT are presented in an option grid distinguishing first-line and second-line ULT. Finally, patients’ believes and preferences are explicitly addressed before making the shared decision.

Conclusion

This study provides initial support for usability of a DA for gout patients eligible for starting ULT.

Discovery of Novel Bicyclic Imidazolopyridine-Containing Human Urate Transporter 1 Inhibitors as Hypouricemic Drug Candidates with Improved Efficacy and Favorable Druggability

Lesinurad is a uricosuric agent for the treatment of hyperuricemia associated with gout, which was found lacking in efficacy and safety. Here, scaffold hopping and molecular hybridization were exploited to modify all the structural components of lesinurad, and 36 novel compounds bearing bicyclic imidazolopyridine core were obtained. In a mouse model of acute hyperuricemia, 29 compounds demonstrated increased serum uric acid (SUA)-reducing activity; SUA was treated with 12, 23, and 29 about fourfold lower compared with that of lesinurad. Moreover, 23 exhibited stronger URAT1 inhibition activity (IC₅₀ = 1.36 μM) than lesinurad (IC₅₀ = 5.54 μM). Additionally, 23 showed favorable safety profiles, and no obvious acute toxicity was observed in Kunming mice under a single dose of 1000 mg·kg^-1. 23 also achieved excellent pharmacokinetic properties with the oral bioavailability of 59.3%. Overall, all the results indicated that 23 is a promising drug candidate in the treatment of hyperuricemia and gout.

Dietary supplements for chronic gout

BACKGROUND

Dietary supplements are frequently used for the treatment of several medical conditions, both prescribed by physicians or self administered. However, evidence of benefit and safety of these supplements is usually limited or absent.

OBJECTIVES

To assess the efficacy and safety of dietary supplementation for people with chronic gout.

SEARCH METHODS

We updated the original search by searching CENTRAL, MEDLINE, Embase, CINAHL, and four trials registers (August 2020). We applied no date or language restrictions. We also handsearched the abstracts from the 2010 to 2019 American College of Rheumatology and European League against Rheumatism conferences, and checked the references of all included studies.

SELECTION CRITERIA

We considered all published randomised controlled trials (RCTs) or quasi-RCTs that compared dietary supplements with no supplements, placebo, another supplement, or pharmacological agents for adults with chronic gout for inclusion. Dietary supplements included, but were not limited to, amino acids, antioxidants, essential minerals, polyunsaturated fatty acids, prebiotic agents, probiotic agents, and vitamins. The major outcomes were acute gout flares, study withdrawal due to adverse events (AEs), serum uric acid (sUA) reduction, joint pain reduction, participant global assessment, total number of AEs, and tophus regression.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

Two previously included RCTs (160 participants) met our inclusion criteria; we did not identify any new trials for this update. As these two trials evaluated different diet supplements (enriched skim milk powder (SMP) and vitamin C) with different outcomes (gout flare prevention for enriched SMP, and sUA reduction for vitamin C), we reported the results separately. One trial (120 participants), at unclear risk of selection and detection bias, compared SMP enriched with glycomacropeptides (GMP) with un-enriched SMP, and with lactose, over three months. Participants were predominantly men, aged in their 50s, who had severe gout. The results for all major outcomes were imprecise, except for pain. None of the results were clinically significant. The frequency of acute gout attacks, measured as the number of flares per month, decreased in all three groups over the three-month study period. The effects of enriched SMP (SMP/GMP/G600) compared with the combined control groups (SMP and lactose powder) at three months in terms of mean number of gout flares per month were not clinically significant (mean (standard deviation (SD)) flares per month: 0.49 (1.52) in SMP/GMP/G60 group versus 0.70 (1.28) in the control groups; absolute risk difference: mean difference (MD) -0.21 flares per month, 95% confidence interval (CI) -0.76 to 0.34; low-quality evidence). The number of withdrawals due to adverse effects was similar between groups (7/40 in SMP/GMP/G600 group versus 11/80 in control groups; (risk ratio (RR) 1.27, 95% CI 0.53 to 3.03); there were 4% more withdrawals in the SMP/lactose groups (10% fewer to 18% more; low-quality evidence). Serum uric acid reduction was similar across groups (mean (SD) -0.025 (0.067) mmol/L in SMP/GMP/G60 group versus -0.010 (0.069) in control groups; MD -0.01, 95% CI -0.04 to 0.01; low-quality evidence). Pain from self-reported gout flares (measured on a 10-point Likert scale) improved slightly more in the GMP/G600 SMP group compared with controls (mean (SD) -1.97 (2.28) in SMP/GMP/G600 group versus -0.94 (2.25) in control groups; MD -1.03, 95% CI -1.89 to -0.17). This was an absolute reduction of 10% (95% CI 20% to 1% reduction; low-quality evidence), which may not be of clinical relevance. The risk of adverse events was similar between groups (19/40 in SMP/GMP/G600 group versus 39/80 in control groups; RR 0.97, 95% CI 0.66 to 1.45); the absolute risk difference was 1% fewer adverse events (1% fewer to 2% more), low-quality evidence). Gastrointestinal events such as nausea, flatulence and diarrhoea were the most commonly reported adverse effects. Data for participant global assessment were not available for analysis; the study did not report tophus regression. One trial (40 participants), at high risk of selection, performance, and detection bias, compared vitamin C alone with allopurinol, and with allopurinol plus vitamin C, in a three-arm study. We only included data from the vitamin C versus allopurinol comparison in this review. Participants were predominantly middle-aged men, and their severity of gout was representative of gout in general. Allopurinol reduced sUA levels more than vitamin C (MD 0.10 mmol/L, 95% CI 0.06 to 0.15), low-quality evidence. The study reported no adverse events; none of the participants withdrew due to adverse events. The study did not assess the rate of gout attacks, joint pain reduction, participant global assessment, or tophus regression.

AUTHORS' CONCLUSIONS

While dietary supplements may be widely used for gout, this review found no high-quality that supported or refuted the use of glycomacropeptide-enriched skim milk powder or vitamin C for adults with chronic gout.

Herbal medicine derived carbon dots: synthesis and applications in therapeutics, bioimaging and sensing

Since the number of raw material selections for the synthesis of carbon dots (CDs) has grown extensively, herbal medicine as a precursor receives an increasing amount of attention. Compared with other biomass precursors, CDs derived from herbal medicine (HM-CDs) have become the most recent incomer in the family of CDs. In recent ten years, a great many studies have revealed that HM-CDs tend to be good at theranostics without drug loading. However, the relevant development and research results are not systematically reviewed. Herein, the origin and history of HM-CDs are outlined, especially their functional performances in medical diagnosis and treatment. Besides, we sort out the herbal medicine precursors, and analyze the primary synthetic methods and the key characteristics. In terms of the applications of HM-CDs, medical therapeutics, ion and molecular detection, bioimaging, as well as pH sensing are summarized. Finally, we discuss the crucial challenges and future prospects.

Hispidin, Harmaline, and Harmine as potent inhibitors of bovine xanthine oxidase: Gout treatment, in vitro, ADMET prediction, and SAR studies

Alkaloids and phenols are potent inhibitors family for many enzymes used in many therapies. We aim to evaluate in vitro and in silico, the inhibition effect of Hispidin, Harmaline, and Harmine as pure molecules to bovine milk xanthine oxidase (BXO), Molecular docking and SAR study with GOLD was done to explain the mechanism of action related to its inhibition, ADMET parameters were checked to confirm their pharmacokinetics (PK) using preADMET 2.0 server, we classified our inhibitors by applying five drug-likeness rules, the best-ranked inhibitors were chosen based on the approved ADMET properties, drug-likeness qualifications, and the best PLPchem score generated by GOLD. The in vitro results show important inhibition activity to BXO comparing to the control with an IC50 of 39.72 ± 3.60 µM, 51.00 ± 1.0 µM, and 48.52 ± 1.76 µM for Hispidin, Harmaline, and Harmine respectively. The in silico results show that Hispidin was the best inhibitor model with approved ADMET properties and qualification in all drug-likeness rules; Harmaline was saved second-best model to BXO with suitable ADMET properties and qualified in most drug-likeness rules. Eventually, Harmine was ranked third potent inhibitor model with acceptable ADMET properties, drug-likeness rules, and PLPchem score. The tested inhibitors could be significant in drug discovery, especially in treating gout disease; therefore, drug development, including clinical trials, should be done with promising results.

Sex differences in response to allopurinol and benzbromarone in gout: a retrospective cohort study

Objective

Owing to lower mean uric acid excretion in women compared with men, uricosuric agents might be preferred in women over xanthine oxidase (XO) inhibitors. We therefore investigated the differences in response to two urate-lowering therapies (ULTs) with different modes of action within and between sexes.

Methods

This retrospective cohort study included patients with a clinical diagnosis of gout who started allopurinol and/or benzbromarone. The successful response to ULT, defined as reaching a serum uric acid (sUA) target of <0.36 mmol/l within 6 months after commencing ULT, was compared between allopurinol and benzbromarone in women and men. Effect modification by sex on differences in response was evaluated.

Results

Allopurinol was started in 255 women and 1045 men, and benzbromarone in 60 women and 205 men. After 6 months, the proportions of women reaching the sUA target were 58.4% and 66.7% for allopurinol and benzbromarone, respectively (difference, −8%; 95% CI: −22%, 5%). The respective proportions in men were 61.0% and 75.6%, respectively (difference, −15%; 95% CI: −21%, −8%). Corrected for confounding, the odds ratio (OR) of reaching the target on benzbromarone vs allopurinol within women was 0.91 (95% CI: 0.47, 1.75), and within men 1.55 (95% CI: 1.04, 2.32). Corrected for confounding, sex was not an effect modifier of the difference in allopurinol and benzbromarone response (OR, 0.59; 95% CI: 0.28, 1.24).

Conclusion

This study did not demonstrate between-sex differences regarding the response to either a uricosuric agent or an XO inhibitor, negating different treatment choices by sex.

Targets and mechanisms of dietary anthocyanins to combat hyperglycemia and hyperuricemia: a comprehensive review

Hyperglycemia and hyperuricemia are both metabolic disorders related to excessive amount of metabolites in blood, which are considered as high risk factors for the development of many chronic diseases. Enzymes, cells, tissues and organs, which are relevant to metabolism and excretion of glucose and UA, are usually regarded to be the targets in treatment of hyperglycemia and hyperuricemia. Several drugs have been commonly applied to combat hyperglycemia and hyperuricemia through various targets but with unignorable side effects. Anthocyanins have become promising alternatives against hyperglycemia and hyperuricemia because of their bio-activities with little side effects. Structurally different anthocyanins from berry fruits, cherries and purple sweet potato lead to the diverse functional activity and property. This review is aimed to illustrate the specific targets that are available for anthocyanins from berry fruits, cherries and purple sweet potato in hyperglycemia and hyperuricemia management, as well as discuss the structure-activity relationship, and the underlying mechanisms associated with intracellular signaling pathway, anti-oxidative stress and anti-inflammation. In addition, the relationship of hyperglycemia and hyperuricemia, and the possibly regulative role of anthocyanins against them, along with the effects of anthocyanins in clinical trial are mentioned.

Novel Human Urate Transporter 1 Inhibitors as Hypouricemic Drug Candidates with Favorable Druggability

Lesinurad, a human urate transporter 1 (URAT1) inhibitor approved as a medication for the treatment of hyperuricemia associated with gout in 2015, can cause liver and renal toxicity. Here, we modified all three structural components of lesinurad by applying scaffold hopping, bioisosterism, and substituent-decorating strategies. In a mouse model of acute hyperuricemia, 21 of the synthesized compounds showed increased serum uric acid (SUA)-reducing activity; SUA was about 4-fold lower in animals treated with 44, 54, and 83 compared with lesinurad or benzbromarone. In the URAT1 inhibition assay, 44 was over 8-fold more potent than lesinurad (IC₅₀: 1.57 μM vs 13.21 μM). Notably, 83 also displayed potent inhibitory activity (IC₅₀ = 31.73 μM) against GLUT9. Furthermore, we also preliminarily explored the effect of chirality on the potency of the promising derivatives 44 and 54. Compounds 44, 54, and 83 showed favorable drug-like pharmacokinetics and appear to be promising candidates for the treatment of hyperuricemia and gout.

Allopurinol-Induced Oral Lichenoid Drug Reaction with Complete Regression after Drug Withdrawal

Background: Lichen planus is a chronic mucocutaneous inflammatory disease. Oral manifestations are common, and may remain exclusive to the oral mucosa without involvement of the skin or other mucosae. A differential diagnosis includes oral lichenoid drug reactions. Allopurinol, which is the first line hypo-uricemic treatment, is often quoted as being a possible offending drug, though oral reactions have rarely been reported. Case presentation: We describe a 59-year-old male gout patient, successfully treated with allopurinol, who developed acute onset of oral lichenoid lesions, involving bilaterally the buccal mucosa, the tongue and the labial mucosa. Histopathology was consistent with a lichen planus or a drug-induced lichenoid reaction. Improvement of the patient's condition after withdrawal of allopurinol confirmed the lichenoid nature of the lesion. Remission was complete after a few weeks. Discussion: Although unusual, allopurinol may induce a lichenoid drug reaction. These reactions may mimic clinically and histopathologically idiopathic lichen planus. Improvement or complete regression of the lesions may be attempted to confirm the diagnosis. According to the latest WHO recommendations, these lesions have a potential for malignant transformation.

Allopurinol-Induced Oral Lichenoid Drug Reaction with Complete Regression after Drug Withdrawal

Background: Lichen planus is a chronic mucocutaneous inflammatory disease. Oral manifestations are common, and may remain exclusive to the oral mucosa without involvement of the skin or other mucosae. A differential diagnosis includes oral lichenoid drug reactions. Allopurinol, which is the first line hypo-uricemic treatment, is often quoted as being a possible offending drug, though oral reactions have rarely been reported. Case presentation: We describe a 59-year-old male gout patient, successfully treated with allopurinol, who developed acute onset of oral lichenoid lesions, involving bilaterally the buccal mucosa, the tongue and the labial mucosa. Histopathology was consistent with a lichen planus or a drug-induced lichenoid reaction. Improvement of the patient’s condition after withdrawal of allopurinol confirmed the lichenoid nature of the lesion. Remission was complete after a few weeks. Discussion: Although unusual, allopurinol may induce a lichenoid drug reaction. These reactions may mimic clinically and histopathologically idiopathic lichen planus. Improvement or complete regression of the lesions may be attempted to confirm the diagnosis. According to the latest WHO recommendations, these lesions have a potential for malignant transformation.

Allopurinol use associated with increased risk of acute myocardial infarction in older people in a case-control study

OBJECTIVE

There is controversy about the association between the allopurinol use and the risk of acute myocardial infarction. The aim of the study was to examine the association between allopurinol use and acute myocardial infarction in older people in Taiwan.

MATERIALS AND METHODS

We used the 2000-2013 database of the Taiwan National Health Insurance Program to conduct a case-control study. Cases were assigned as subjects aged 65 years and older with the first incident acute myocardial infarction. Matched controls were assigned as subjects aged 65 years and older without any type of coronary artery disease. Ever use of allopurinol was defined as subjects who had at least a prescription of allopurinol before the diagnosis date of first incident acute myocardial infarction. The odds ratio (OR) and the 95% confidence interval (CI) for acute myocardial infarction associated with allopurinol use were estimated by the multivariable logistic regression model.

RESULTS

There were 4701 cases with the first incident acute myocardial infarction and 9369 matched controls. The adjusted OR of acute myocardial infarction was 2.2 (95% CI 1.7- 2.7) for subjects with ever use of allopurinol, compared with never use. The adjusted ORs of acute myocardial infarction were 2.0 (95% CI 1.5-2.6) for subjects with average daily dosage of allopurinol <200 mg and 2.5 (95% CI 1.6-4.0) for subjects with average daily dosage of allopurinol ≥200 mg.

CONCLUSION

Allopurinol use is associated with increased odds of acute myocardial infarction in older people, which is dosage dependent.

Highly Acylated Anthocyanins from Purple Sweet Potato ( Ipomoea batatas L.) Alleviate Hyperuricemia and Kidney Inflammation in Hyperuricemic Mice: Possible Attenuation Effects on Allopurinol

Allopurinol is the first-line medication for hyperuricemia treatment. However, severe drug-related adverse effects have often been reported among patients who received allopurinol administration. This study is aimed at evaluating the possible attenuation effects of highly acylated anthocyanins from purple sweet potato (HAA-PSP) on hyperuricemia and kidney inflammation in hyperuricemic mice treated with allopurinol. In comparison with 5 mg kg^-1 allopurinol used alone, the combination of 25 mg kg^-1 HAA-PSP and 2.5 mg kg^-1 allopurinol could not only reduce serum uric acid level in hyperuricemic mice but also attenuate the kidney damage, as indicated by the level of serum biomarkers as well as histopathological examination. The inflammatory response was partially mitigated by inhibiting the protein expression of typical cytokines in the kidney. Our findings provide new evidence for the supplementary therapeutic potential of HAA-PSP with allopurinol on hyperuricemia and inflammation-related syndromes. Moreover, this study provides a theoretical basis for assessing the potential of anthocyanin-rich foods in health.

[Ru(bpy)2(NO)SO3](PF6), a Nitric Oxide Donating Ruthenium Complex, Reduces Gout Arthritis in Mice

Monosodium urate crystals (MSU) deposition induces articular inflammation known as gout. This disease is characterized by intense articular inflammation and pain by mechanisms involving the activation of the transcription factor NFκB and inflammasome resulting in the production of cytokines and oxidative stress. Despite evidence that MSU induces iNOS expression, there is no evidence on the effect of nitric oxide (NO) donors in gout. Thus, the present study evaluated the effect of the ruthenium complex donor of NO {[Ru(bpy)₂(NO)SO₃](PF₆)} (complex I) in gout arthritis. Complex I inhibited in a dose-dependent manner MSU-induced hypersensitivity to mechanical stimulation, edema and leukocyte recruitment. These effects were corroborated by a decrease of histological inflammation score and recruitment of Lysm-eGFP⁺ cells. Mechanistically, complex I inhibited MSU-induced mechanical hypersensitivity and joint edema by triggering the cGMP/PKG/ATP-sensitive K (+) channels signaling pathway. Complex I inhibited MSU-induced oxidative stress and pro-inflammatory cytokine production in the knee joint. These data were supported by the observation that complex I inhibited MSU-induced NFκB activation, and IL-1β expression and production. Complex I also inhibited MSU-induced activation of pro-IL-1β processing. Concluding, the present data, to our knowledge, is the first evidence that a NO donating ruthenium complex inhibits MSU-induced articular inflammation and pain. Further, complex I targets the main physiopathological mechanisms of gout arthritis. Therefore, it is envisaged that complex I and other NO donors have therapeutic potential that deserves further investigation.

Gout, Hyperuricemia, and Crystal-Associated Disease Network Consensus Statement Regarding Labels and Definitions for Disease Elements in Gout

OBJECTIVE

The language currently used to describe gout lacks standardization. The aim of this project was to develop a consensus statement on the labels and definitions used to describe the basic disease elements of gout.

METHODS

Experts in gout (n = 130) were invited to participate in a Delphi exercise and face-to-face consensus meeting to reach consensus on the labeling and definitions for the basic disease elements of gout. Disease elements and labels in current use were derived from a content analysis of the contemporary medical literature, and the results of this analysis were used for item selection in the Delphi exercise and face-to-face consensus meeting.

RESULTS

There were 51 respondents to the Delphi exercise and 30 attendees at the face-to-face meeting. Consensus agreement (≥80%) was achieved for the labels of 8 disease elements through the Delphi exercise; the remaining 3 labels reached consensus agreement through the face-to-face consensus meeting. The agreed labels were monosodium urate crystals, urate, hyperuric(a)emia, tophus, subcutaneous tophus, gout flare, intercritical gout, chronic gouty arthritis, imaging evidence of monosodium urate crystal deposition, gouty bone erosion, and podagra. Participants at the face-to-face meeting achieved consensus agreement for the definitions of all 11 elements and a recommendation that the label "chronic gout" should not be used.

CONCLUSION

Consensus agreement was achieved for the labels and definitions of 11 elements representing the fundamental components of gout etiology, pathophysiology, and clinical presentation. The Gout, Hyperuricemia, and Crystal-Associated Disease Network recommends the use of these labels when describing the basic disease elements of gout.

The impact of xanthine oxidase (XO) on hemolytic diseases

Hemolytic diseases are associated with elevated levels of circulating free heme that can mediate endothelial dysfunction directly via redox reactions with biomolecules or indirectly by upregulating enzymatic sources of reactive species. A key enzymatic source of these reactive species is the purine catabolizing enzyme, xanthine oxidase (XO) as the oxidation of hypoxanthine to xanthine and subsequent oxidation of xanthine to uric acid generates superoxide (O₂^•-) and hydrogen peroxide (H₂O₂). While XO has been studied for over 120 years, much remains unknown regarding specific mechanistic roles for this enzyme in pathologic processes. This gap in knowledge stems from several interrelated issues including: 1) lethality of global XO deletion and the absence of tissue-specific XO knockout models have coalesced to relegate proof-of-principle experimentation to pharmacology; 2) XO is mobile and thus when upregulated locally can be secreted into the circulation and impact distal vascular beds by high-affinity association to the glycocalyx on the endothelium; and 3) endothelial-bound XO is significantly resistant (> 50%) to inhibition by allopurinol, the principle compound used for XO inhibition in the clinic as well as the laboratory. While it is known that circulating XO is elevated in hemolytic diseases including sickle cell, malaria and sepsis, little is understood regarding its role in these pathologies. As such, the aim of this review is to define our current understanding regarding the effect of hemolysis (free heme) on circulating XO levels as well as the subsequent impact of XO-derived oxidants in hemolytic disease processes.

Impact of Non-Adherence and Flare Resolution on the Cost-Effectiveness of Treatments for Gout: Application of a Linked Pharmacometric/Pharmacoeconomic Model

BACKGROUND

Dual urate-lowering therapy (ULT) with lesinurad in combination with either allopurinol or febuxostat is an option for patients with gout unsuccessfully treated on either monotherapy. Treatment failure is often a result of poor medication adherence. Imperfect adherence in clinical trials may lead to biased estimates of treatment effect and confound the results of cost-effectiveness analyses.

OBJECTIVES

To estimate the impact of varying medication adherence on the cost effectiveness of lesinurad dual therapy and estimate the value-based price of lesinurad at which the incremental cost-effectiveness ratio is equal to £20,000 per quality-adjusted life-year (QALY).

METHODS

Treatment effect was simulated using published pharmacokinetic-pharmacodynamic models and scenarios representing adherence in clinical trials, routine practice, and perfect use. The subsequent cost and health impacts, over the lifetime of a patient cohort, were estimated using a bespoke pharmacoeconomic model.

RESULTS

The base-case incremental cost-effectiveness ratios comparing lesinurad dual ULT with monotherapy ranged from £39,184 to £78,350/QALY gained using allopurinol and £31,901 to £124,212/QALY gained using febuxostat, depending on the assumed medication adherence. Results assuming perfect medication adherence imply a per-quarter value-based price of lesinurad of £45.14 when used in dual ULT compared with allopurinol alone and £57.75 compared with febuxostat alone, falling to £25.41 and £3.49, respectively, in simulations of worsening medication adherence.

CONCLUSIONS

The estimated value-based prices of lesinurad only exceeded that which has been proposed in the United Kingdom when assuming both perfect drug adherence and the eradication of gout flares in sustained treatment responders.

Patient-reported gout attack frequency and allopurinol use in general practice in the Netherlands: a prospective observational cohort study protocol

INTRODUCTION

Gout is the most common inflammatory arthritis in the Dutch general practice population and is often managed with long-term uric acid lowering treatment. The clinical relevance of this treatment in preventing gout attacks is unclear.

PRIMARY RESEARCH QUESTION

What is the frequency of self-reported gout attacks and what is the effect of allopurinol use in patients diagnosed with gout in general practice?

METHODS AND ANALYSIS

Adult patients with a diagnostic consultation code for gout in the year 2013, 2014 or 2015 will be invited to participate in this prospective observational cohort study. Patients with a limited life expectancy will be excluded. Baseline measurements will include blood pressure, body mass index and a blood sample (estimated glomerular filtration rate, serum uric acid, cholesterol (low-density lipoprotein (LDL) and high-density lipoprotein), glucose (fasting)). At the 2-year follow-up, patients will receive questionnaires every 3 months. The questionnaires at baseline, 12 months and 24 months assess the frequency of gout attacks, the presence of tophi, comorbidity, medication use, quality of life, diet and lifestyle. The questionnaires in between only assess the frequency of gout attacks and medication use for gout. Descriptive statistics will be used to calculate the mean frequency of self-reported gout attacks during the 2-year follow-up. The propensity score for each patient being offered allopurinol is estimated and used to match patients with and without allopurinol treatment. We will compare the frequency of gout attacks in these groups using multilevel Poisson regression analyses. With this type of analysis, we can calculate the corrected estimated effect of allopurinol on gout attack frequency.

ETHICS AND DISSEMINATION

The research protocol was approved by the Medical Ethical Committee of the Erasmus Medical Centre in Rotterdam. The knowledge generated by this study will be transferred to the Dutch College of General Practitioners, conferences and to (inter)national peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NTR6329; Pre-results.

Treatment Options for Gout

BACKGROUND

1-2% of adults in Germany suffer from gout. Gout is one of the few rheumatological diseases that can be cured. It arises through the deposition of uric acid crystals in joints as a result of hyperuricemia. Painful redness and swelling of the affected joints are typical findings. Multiple pertinent guidelines and treatment recommendations have been published, but there is reason to believe that patients with gout are not always treated accordingly.

METHODS

This review is based on relevant publications from the years 2000-2016 that were retrieved by a selective search in the Cochrane and PubMed databases.

RESULTS

In a person with normal renal function, asymptomatic hyperuricemia is not an indication for treatment to lower the serum uric acid level. The drugs of first choice for acute gouty arthritis are nonsteroidal antiinflammatory drugs (NSAID), corticosteroids, and colchicine. Treatment with xanthine oxidase inhibitors (XOI) or uricosuric drugs is indicated for patients with a recurrent or severe course; the target uric acid value is <6 mg/dL. Long-term treatment should be initiated only after resolution of the acute attack. For patients with refractory gout, lesinurad (approved in February 2016) in combination with XOI is a new treatment option that can be considered. Comprehensive patient education and counseling is an important component of the treatment of patients with gout. Regular laboratory follow-up is necessary as well.

CONCLUSION

The prevalence of gout is rising around the world. Patients with gout could benefit greatly from consistent implementation of the existing treatment guidelines and recommendations. In the future, controlled trials should be conducted to determine the best time to start treatment and the optimal target level for the serum uric acid concentration in terms of a risk/benefit analysis.

Side Effects and Interactions of the Xanthine Oxidase Inhibitor Febuxostat

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

An update on the management of gout

Gout is the most common form of inflammatory arthritis and its incidence in the UK has steadily increased from 1.5% in 1997 to 2.5% in 2012.^1,2 It is characterised by deposition of monosodium urate crystals in joints and tissues and usually presents with intermittent painful attacks followed by long periods of remission.³ It has been suggested that the management of gout in the UK remains suboptimal.¹ In 2004, we concluded that there was a woeful lack of evidence to guide treatment or prophylaxis for gout, particularly with regard to choice of drug or doses.⁴ The introduction of new drugs and new evidence on the efficacy and safety of treatment options has led the European League Against Rheumatism (EULAR) and the British Society of Rheumatology (BSR) to update their guidelines on the management of gout.^2,5 Nevertheless, there are differing views on target serum uric acid (SUA) levels and the role of urate lowering treatment (ULT).^2,5-7 Here, we review the latest guidance on the management of gout and consider the role of long-term ULT.

Guideline development for the management of gout: role of combination therapy with a focus on lesinurad

The aim of this review was to summarize the evidence for combination therapy to achieve serum urate (SUA) target levels in gout. Within this overarching aim, a second aim was to evaluate the evidence for a new uricosuric agent lesinurad, which inhibits urate transport in the kidney. In summary, this review indicates that there are a number of ways to approach patients who do not achieve a target serum urate with allopurinol (APL) monotherapy. These include higher doses of APL up to 600–800 mg/d, switching to febuxostat, or adding in a uricosuric. For the latter option, controlled supporting evidence is available for benzbromarone, probenecid, and lesinurad. All options appear similar in terms of success rates, so the choice of option comes down to physician and patient choice, cost, experience, and strength of the evidence base. Increasing the dose of APL is the cheapest option, while febuxostat is consistently superior to standard doses of APL. The strongest evidence for the uricosuric option is available for lesinurad as trials of other agents are either nonexistent or based on small single-centre trials. It is suggested that guidelines should be expanded to consider all of these evidence-based options in the not-uncommon occurrence of APL inadequate response.

Does the initiation of urate-lowering treatment during an acute gout attack prolong the current episode and precipitate recurrent attacks: a systematic literature review

The aim of this study was to systematically review the literature on effect of initiating urate-lowering treatment (ULT) during an acute attack of gout on duration of index attack and persistence on ULT. OVID (Medline), EMBASE and AMED were searched to identify randomized controlled trials (RCTs) of ULT initiation during acute gout attack published in English language. Two reviewers appraised the study quality and extracted data independently. Standardized mean difference (SMD) and relative risk (RR) were used to pool continuous and categorical data. Meta-analysis was carried out using STATA version 14. A total of 537 studies were selected. A total of 487 titles and abstracts were reviewed after removing duplicates. Three RCTs were identified. There was evidence from two high-quality studies that early initiation of allopurinol did not increase pain severity at days 10–15 [SMD_pooled (95 % CI) 0.18 (−0.58, 0.93)]. Data from three studies suggested that initiation of ULT during an acute attack of gout did not associate with dropouts [RR_pooled (95 % CI) 1.16 (0.58, 2.31)]. There is moderate-quality evidence that the initiation of ULT during an acute attack of gout does not increase pain severity and risk of ULT discontinuation. Larger studies are required to confirm these findings so that patients with acute gout can be initiated on ULT with confidence.

De-crystallization of Uric Acid Crystals in Synovial Fluid Using Gold Colloids and Microwave Heating

In this study, we demonstrated a unique application of our Metal-Assisted and Microwave-Accelerated Evaporative Crystallization (MA-MAEC) technique for the de-crystallization of uric acid crystals, which causes gout in humans when monosodium urate crystals accumulate in the synovial fluid found in the joints of bones. Given the shortcomings of the existing treatments for gout, we investigated whether the MA-MAEC technique can offer an alternative solution to the treatment of gout. Our technique is based on the use of metal nanoparticles (i.e., gold colloids) with low microwave heating to accelerate the de-crystallization process. In this regard, we employed a two-step process; (i) crystallization of uric acid on glass slides, which act as a solid platform to mimic a bone, (ii) de-crystallization of uric acid crystals on glass slides with the addition of gold colloids and low power microwave heating, which act as “nano-bullets” when microwave heated in a solution. We observed that the size and number of the uric acid crystals were reduced by >60% within 10 minutes of low power microwave heating. In addition, the use of gold colloids without microwave heating (i.e. control experiment) did not result in the de-crystallization of the uric acid crystals, which proves the utility of our MA-MAEC technique in the de-crystallization of uric acid.