New and Pipeline Drugs for Gout

Gout is the most common inflammatory arthropathy in the western world. Affecting millions and accounting for lost wages, increased health care costs, and significant disability, it remains a burden for those afflicted, their families, and the health care system. Despite the availability of a number of effective therapies, gout is often inadequately treated, and its impact on the patients overall health and well-being is underestimated by physicians and patients alike. For many decades, controlling acute flares was the priority in the management of gout. More recently, however, a deeper understanding of gout pathophysiology has resulted in a new appreciation that gout impacts the patient with consequences well beyond the episodes of acute inflammatory arthritis. Reflecting the chronic nature of the disease, gout treatment needs to be chronic as well, and aimed at reducing the underlying cause of gout—hyperuricemia—as well as the symptom of acute attacks. Therapy therefore requires both urate lowering and anti-inflammatory strategies. Unfortunately, the most commonly used urate lowering and anti-inflammatory treatments may be problematic in some gout patients, who often have multiple comorbidities that establish relative contraindications. Novel urate lowering therapies, and new medications to treat and prevent acute gouty flares, can not only improve care of the individual; they can also lead to a better discourse for the edification of those who manage and are managed for this underestimated disease. In this paper, we discuss new and pipeline drugs for acute gout, prophylactic anti-inflammatory therapies as well as urate lowering therapies.     

Management of gout and hyperuricemia: Multidisciplinary consensus in Taiwan

Gout is an inflammatory disease manifested by the deposition of monosodium urate (MSU) crystals in joints, cartilage, synovial bursa, tendons or soft tissues. Gout is not a new disease, which was first documented nearly 5,000 years ago. The prevalence of gout has increased globally in recent years, imposing great disease burden worldwide. Moreover, gout or hyperuricemia is clearly associated with a variety of comorbidities, including cardiovascular diseases, chronic kidney disease, urolithiasis, metabolic syndrome, diabetes mellitus, thyroid dysfunction, and psoriasis. To prevent acute arthritis attacks and complications, earlier use of pharmacotherapeutic treatment should be considered, and patients with hyperuricemia and previous episodes of acute gouty arthritis should receive long‐term urate‐lowering treatment. Urate‐lowering drugs should be used during the inter‐critical and chronic stages to prevent recurrent gout attacks, which may elicit gradual resolution of tophi. The goal of urate‐lowering therapy should aim to maintain serum uric acid (sUA) level <6.0 mg/dL. For patients with tophi, the initial goal can be set at lowering sUA to <5.0 mg/dL to promote tophi dissolution. The goal of this consensus paper was to improve gout and hyperuricemia management at a more comprehensive level. The content of this consensus paper was developed based on local epidemiology and current clinical practice, as well as consensuses from two multidisciplinary meetings and recommendations from Taiwan Guideline for the Management of Gout and Hyperuricemia.     

Hyperuricemia and gout

Gout is not a new disease for clinicians; nevertheless, there are still many secrets awaiting discovery for improving knowledge with respect to uric acid metabolism and monosodium urate crystal-induced inflammation. This review of the literature will focus on new insights on the pathogenesis of idiopathic hyperuricemia, and on secondary hyperuricemia and gout. There are also important advances on the pathophysiology of acute gout, especially as a self-limited process (switch from monocyte to macrophage, peroxisome proliferator activated receptor-gamma, and nitric oxide), but also of chronic gouty arthropathy. Armaments for treating hyperuricemia and gout may be already improved by losartan or fenofibrate and, in the future, by urate oxydase-polyethylene glycol 20 and renal handling regulatory molecules. Finally, control of hyperuricemia may also be considered in the prevention and treatment of cardiovascular disease.     

Clinical aspects of monosodium urate monohydrate crystal deposition disease (gout)

Gout is a clinical syndrome with a limited range of manifestations arising as a result of the deposition of crystals of monosodium urate, the final product of purine metabolism in humans. Hyperuricemia is a common chemical aberration that is most often mild and remains asymptomatic. Thus, hyperuricemia should be distinguished from gout, even though urate supersaturation is necessary for the expression of gout. Uric acid overproduction and diminished renal uric acid excretion are the major mechanisms resulting in hyperuricemia, and an understanding of the basis of hyperuricemia in individual gout patients is an important step in determining appropriate treatment and in identifying underlying disorders, offending drugs and toxins, and inherited enzyme defects, all of which can result in hyperuricemia and gout. A scheme is presented for the evaluation of patients with new-onset gout, along with a discussion of the relationships between gout/hyperuricemia and a variety of metabolic disorders that are unusually prevalent in gouty populations.     

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 goutpatients must be early screened for cardiovascular risk factors.     

Recent advances in the epidemiology of gout

Gout remains among the most common of all inflammatory arthridities with an incidence that appears to have risen. Evidence is accumulating to support lifestyle and dietary factors, such as heavy consumption of beer and liquor as well as diets rich in meats and seafood as important gout risk factors. There is also a renewed interest in important associations between gout and other comorbidities like hypertension and cardiovascular disease. The importance of hyperuricemia on health considerations beyond the musculoskeletal system is an area worthy of even more study.     

Regulation of Uric Acid Excretion by the Kidney

It has been known for many years that the kidney plays a major role in uric acid homeostasis, as more than 70% of urate excretion is renal. Furthermore, hyperuricemia in gout is most commonly the result of relative urate underexcretion, as the kidney has enormous capacity for urate reabsorption. A clear understanding of the mechanisms of renal handling of urate has been hampered by the differences between humans and animal models. The power of human genetics and genome-wide association studies has now provided new insight into the molecular mechanisms of urate transport by identifying the transporters that have critical roles in urate transport. This review surveys the new evidence for a molecular model of urate transport in the renal proximal tubule and uses these data to refute the popular four-component model for urate transport that has long been in vogue. It also discusses data that help us understand the relation of diuretics to hyperuricemia, losartan-induced uricosuria, variations in uric acid levels in hyperglycemia, and the effects of dairy diets on serum urate levels. In the end, several of these clinical findings are explained, and the remaining gaps in our knowledge will become evident.     

Recent advances in the epidemiology of gout

Gout remains among the most common of all inflammatory arthridities with an incidence that appears to have risen. Evidence is accumulating to support lifestyle and dietary factors, such as heavy consumption of beer and liquor as well as diets rich in meats and seafood as important gout risk factors. There is also a renewed interest in important associations between gout and other comorbidities like hypertension and cardiovascular disease. The importance of hyperuricemia on health considerations beyond the musculoskeletal system is an area worthy of even more study.     

Comorbidities of gout and hyperuricemia in the US general population: NHANES 2007-2008

PurposeThe objective of this study was to estimate the latest prevalence of major comorbidities associated with gout and hyperuricemia in the US based on a recent, nationally representative sample of US men and women.MethodsUsing data from 5707 participants aged 20 years and older in the National Health and Nutrition Examination Survey 2007-2008, we calculated the national prevalence and population estimates of major comorbidities according to gout status and various hyperuricemia levels, compared with those without these conditions. Case definitions of gout and comorbidities were based on an affirmative answer to a question that asked whether a physician or a health professional had diagnosed the corresponding condition.ResultsAmong these individuals with gout, 74% (6.1 million) had hypertension, 71% (5.5 million) had chronic kidney disease stage ≥2, 53% (4.3 million) were obese, 26% (2.1 million) had diabetes, 24% (2.0 million) had nephrolithiasis, 14% (1.2 million) had myocardial infarction, 11% (0.9 million) had heart failure, and 10% (0.9 million) had suffered a stroke. These proportions were substantially higher than those among individuals without gout (all P-values <.67). With increasing levels of hyperuricemia, there were graded increases in the prevalences of these comorbidities. In the top category (serum urate ≥10 mg/dL), 86% of subjects had chronic kidney disease stage ≥2, 66% had hypertension, 65% were obese, 33% had heart failure, 33% had diabetes, 23% had myocardial infarction, and 12% had stroke. These prevalences were 3-33 times higher than those in the lowest serum urate category (<4 mg/dL). Sex-specific odds ratios tended to be larger among women than men, and the overall comorbidity prevalence was highest among individuals with both gout and hyperuricemia.ConclusionsThese findings from the latest nationally representative data highlight remarkable prevalences and population estimates of comorbidities of gout and hyperuricemia in the US. Appropriate preventive and management measures of these comorbidities should be implemented in gout management, with a preference to strategies that can improve gout and comorbidities together.     

Gout: epitome of painful arthritis

Arthritic pain and disability are at or near the top of the list of reasons adult patients seek medical attention. At least 47.8 million US residents have arthritis. In Europe, the magnitude of the problem is similar, affecting 8 million in the United Kingdom and 108 million across the continent. Osteoarthritis is by far the most common form of arthritis. In a regional UK study, nearly half of adults 50 years or older reported some form of osteoarthritic knee pain over a 1-year period. Among the arthritides, gout is notable for the agonizing nature and unique pathogenesis of the pain it generates. Gout is the most common cause of inflammatory arthritis among men and postmenopausal women. Because of the atypical nature of some of its clinical manifestations, gout can present serious diagnostic challenges for practicing physicians. In recent years, knowledge about gout's pathogenesis, pathophysiology, and differential diagnosis has advanced on a broad front. Genetic variants within a newly identified transport gene, SLC2A9, have been associated with a low fractional excretion of uric acid and the presence of gout in several population samples. The SLC2A9 gene encodes glucose transporter 9—a unique hexose and high-capacity urate transporter. In addition, human ATP-binding cassette, subfamily G2 (ABCG2), encoded by the ABCG2 gene, has been found to mediate renal urate secretion. Introduction of a mutation encoded in a model system by a common single nucleotide polymorphism, rs2231142, resulted in a 53% reduction in urate transport rates compared with wild-type ABCG2. Based on a large population study, it has been estimated that at least 10% of all gout cases in white persons may be attributable to this single nucleotide polymorphism causal genetic variant. Of the various categories of arthritis, the crystal-induced arthropathies, gout and pseudogout, are manifested by acute inflammation and tissue damage arising from deposition in joints and periarticular tissues of monosodium urate (MSU), calcium pyrophosphate dehydrate, or basic calcium phosphate crystals. The innate immune system rapidly detects invading pathogenic microbes and nonmicrobial “danger signals” such as MSU crystals. When these crystals are deposited in synovial tissues, NLR proteins (NOD-like receptors) form multiprotein complexes known as inflammasomes that trigger secretion of inflammation-producing cytokines like interleukin-1β and interleukin-18. Usually, gout can be diagnosed by medical history, physical examination, and presence of hyperuricemia (urate >416 μmol/L). However, a urate concentration less than 416 does not by itself rule out gout. Confirmation of the diagnosis by identification of typical MSU crystals in aspirated synovial fluid is definitive. Analysis of joint fluid is mandatory to rule out septic arthritis, which can rapidly become lethal. Because of its special ability to identify and quantitate urate deposits in peripheral tissues, dual-energy computed tomography should prove valuable in the differential diagnosis of gout. Gout mimics a variety of illnesses; for example, spinal gout may masquerade as metastatic cancer, epidural abscess, and nerve compression syndrome.     

Importance of Adherence in the Outcome of Juvenile Idiopathic Arthritis

Gout was first recognized as a distinct clinical entity in antiquity. Our understanding of the epidemiology and treatment of gout has evolved over millennia intertwined with observations about social class and plant and animal sources of food, beverages and medicines. Investigators have identified various aspects of diet that relate to gout risk and recurrence. Some of our most useful medications for the treatment of gout were developed from herbal precursors. Traditional dietary recommendations for gout patients have included limiting high purine meat and alcohol consumption. More recent work suggests diets leading to weight loss through calorie and carbohydrate reductions may be effective for lowering serum urate levels, as well as the risk of gout.     

Gout: diagnosis, pathogenesis, and clinical manifestations

Gout is a common form of arthritis, in which many of the risk factors, pathogenetic mechanisms, and clinical features have been recognized for years. Nevertheless, new information has become available regarding the normal physiologic role of uric acid as an antioxidant, and greater insight has been obtained regarding the inflammatory process in acute gout. New studies have improved our understanding of the role of genetic and environmental factors responsible for hyperuricemia, and we know more about the significance of the association of hyperuricemia with other diseases. Clinically, rare complications and disease manifestations in new populations continue to be discussed, and diagnostic methods continue to be refined.     

Influence of intestinal microecology in the development of gout or hyperuricemia and the potential therapeutic targets

Gout and hyperuricemia are common metabolic diseases. Patients with purine metabolism disorder and/or decreased uric acid excretion showed increased uric acid levels in the blood. The increase of uric acid in the blood leads to the deposition of urate crystals in tissues, joints, and kidneys, and causes gout. Recent studies have revealed that imbalance of the intestinal microecology is closely related to the occurrence and development of hyperuricemia and gout. Disorder of the intestinal flora often occurs in patients with gout, and high purine and high fructose may induce the disorder of intestinal flora. Short-chain fatty acids and endotoxins produced by intestinal bacteria are closely related to the inflammatory response of gout. This article summarizes the characteristics of intestinal microecology in patients or animal models with hyperuricemia or gout, and explores the relationship between intestinal microecology and gout or hyperuricemia from the aspect of the intestinal barrier, intestinal microorganisms, intestinal metabolites, and intestinal immune system. We also review the current status of hyperuricemia treatment by targeting intestinal microecology.     

Gout and arrhythmias: In search for causation beyond association

Gout is a systemic disease, characterized by the formation and deposition of crystals in tissues (mainly in and around the joints) of individuals with elevated serum uric acid levels. Lately, a considerable number of reports relating elevated uric acid and/or gout with rhythm disorders, such as atrial fibrillation, have been published. This review summarizes evidence linking common arrhythmias and hyperuricemia/gout and discusses questions or controversies that surround it. Overall, existing evidence may not be overwhelming, but strongly suggests a positive correlation between uric acid levels and common rhythm disorders. Needless to say that such a link – as a univariate association between the two – is to be expected, given the extensive overlap of risk factors and comorbidities of hyperuricemia/gout and arrhythmias. However, the observed associations seem to persist – in most studies – after extensive adjustment for potential confounders. Still, multivariable analyses of epidemiologically collected data cannot substitute for proof coming from basic and clinical studies. There is obviously a need for further basic research to establish a causal relationship between uric acid effects and arrhythmias, as well as translational studies and clinical trials to investigate the therapeutic implications of such a relationship. Simply put, we are fairly certain that there is association, but proof of causation is what we are still in want of.     

Pathogenesis, diagnostics and therapy of gout

Gout refers to heterogeneous group of metabolic diseases characterized by production of deposits of sodium urate crystals in tissues. Gout manifests as acute gouty arthritis with classic clinical picture, or as chronic gouty arthropathy with periarticular and subcutaneous deposits of sodium urate crystals, i.e. tophi. As for kidney, gout is manifested as acute or chronic gouty nephropathy and urolithiasis. These manifestations occur separately or they are combined. Hyperuricemia of primary gout is caused rather by impaired renal secretion than overproduction of uric acid. Secondary hyperuricemia is associated with many pathological conditions; it is also connected with the use of various medicaments. Pathogenesis of gouty arthritis is critically influenced by sodium urate crystals and inflammatory processes they induce. Hyperuricemia is part of metabolic syndrome X which is associated with unanswered question of the relationship between uric acid and atherosclerosis. Although gouty arthritis is the most frequent inflammatory disease of joints in men over 50 years of age, it is often diagnosed and treated inadequately. On that account, the indication of long-term hypouricemic therapy should be always based on the following criteria: secondary causes of hyperuricemia have to be excluded first; frequency of gout attacks and the risk of their recurrence should be taken into consideration; then it is necessary to search for renal manifestations of gout; and last but not least, we should check whether there are any associated diseases classified in metabolic syndrome X.     

Gout and hyperuricemia

Gout continues to be a health problem around the world despite the availability of effective therapies. Although the prevalence is influenced by genetic factors, the associations of alcohol consumption, obesity, and hypertension appear to be partially responsible for the increased prevalence of gout and hyperuricemia in African and Oriental countries. The association between hyperuricemia and cardiovascular disease seems linked to insulin resistance. This relation, in part, explains the common coexistence of hyperlipidemia and glucose intolerance in patients with gout. Accordingly, it is recommended that one pay more attention to dietary manipulation in patients with gout in addition to managing hypertension, obesity, and other medical problems. Although acute gout attacks can be treated, eliminating gout requires effective removal of urate from the body. Allopurinol remains a dominant urate-lowering agent, however its use may be limited by allergic reactions. Uricosuric agents are also effective urate-lowering agents and provide an alternative to allopurinol. Strategies to treat patients who are sensitive to allopurinol continue to evolve.     

Acute gouty arthritis during pyrazinamide treatment: a case report

Gout is a disease caused by an inflammatory response to an aggregation of monosodium urate crystals that develop secondary to hyperuricemia. Throughout its natural history it has four stages: asymptomatic hyperuricemia, acute gouty arthritis, intercritical gout, and chronic tophaceous gout. In this article, we report the case of a patient who had asymptomatic hyperuricemia secondary to pyrazinamide, which was prescribed for pulmonary tuberculosis, and had developed an acute gouty arthritis immediately after the “Feast of Sacrifice” due to a dietary excess of purine.