The management of gout

Successful treatment of refractory gout using combined therapy consisting of febuxostat and allopurinol in a patient with chronic renal failure

Gouty arthritis is a metabolic disorder associated with hyperuricemia. Despite the development of novel pharmacotherapies, some hyperuricemia patients are drug refractory and develop gout. A 74-year-old man with frequent gouty attacks and chronic renal failure presented with asymmetrical polyarthritis affecting multiple joints. The diagnosis of gout was confirmed based on the presence of monosodium urate crystals in the patient's right wrist. The administration of systemic corticosteroids relieved the joint inflammation and pain; however, the urate level increased to 28 mg/dL and the gout attacks recurred. Combined allopurinol, febuxostat, and benzbromarone therapy reduced the urate level to <6 mg/dL, and the attacks gradually declined. This is the first report of two xanthine oxidase inhibitors being used to treat refractory gout.

Role of colchicine-induced microtubule depolymerization in hyperalgesia via TRPV4 in rats with chronic compression of the dorsal root ganglion

The aim of this study is to investigate the effect of microtubule depolymerization by colchicine on hyperalgesia mediated by transient receptor potential vanilloid 4 (TRPV4) in a neuropathic pain model of chronic compression of the dorsal root ganglion (DRG) (hereafter termed CCD) in rat. Intrathecal administration of microtubule-depolymerizing agent, colchicine, attenuated the activated effect of 4alpha-phorbol 12, 13-didecanoate (4alpha-PDD, TRPV4 specific agonist) on mechanical and thermal hyperalgesia in CCD rats. This observation is in agreement with our in vitro experiments with DRG cells that showed a significant attenuation of 4alpha-PDD-activated Ca(2+)-influx and substance P (SP) release with the colchicine treatment. We conclude that microtubule depolymerization by colchicine can regulate pain sensitivity by depressing the hyperalgesia mediated by TRPV4.

Xanthine oxidase inhibitory activity and hypouricemic effect of aspalathin from unfermented rooibos

Rooibos is rich in flavonoids such as aspalathin, which is a unique C-glycosyl dihydrochalcone, that is used as a traditional herbal tea. This study was designed to evaluate the in vitro xanthine oxidase (XOD) inhibitory activity of the aspalathin-rich fraction (ARF) and purified aspalathin from rooibos. The hypouricemic effects of the ARF and aspalathin on hyperuricemic mice were also assessed. The ARF was prepared from aqueous extract of unfermented rooibos leaves and stems, and it was collected by column chromatography; the aspalathin content in this fraction was 21.4%. The ARF and aspalathin inhibited XOD in a dose-dependent manner. The concentrations of the ARF and aspalathin required to inhibit XOD at 50% (IC50 ) were 20.4 μg/mL (4.4 μg/mL aspalathin equivalents) and 4.5 μg/mL, respectively. Lineweaver-Burk plot analysis indicated that aspalathin was a competitive inhibitor of XOD, and the inhibition constant (Ki) was 3.1 μM. In hyperuricemic mice induced by inosine-5'-monophosphate, treatment with the ARF and aspalathin significantly suppressed the increased plasma uric acid level in a dose-dependent manner. The suppressed plasma uric acid level in mice could be attributed to the XOD inhibitory activity of the ARF and aspalathin. Further study is required to determine the effect of aspalathin or its metabolites on XOD activity in vivo.

A novel metabolic balance model for describing the metabolic disruption of and interactions between cardiovascular-related markers during acute myocardial infarction

OBJECTIVE

After acute myocardial infarction (AMI), an integral evaluation of risk using multimarker approach and the understanding of the pathophysiological processes involved have recently received much attention. This study aimed to develop a model to integrally evaluate the metabolic disruption of cardiovascular-related markers and unveil their interactions after AMI.

METHODS

AMI was induced in rats by coronary artery ligation. Several cardiovascular-related markers in plasma and the heart were determined during AMI. A metabolic balance model was developed using matrix equations to assess the metabolic disturbance of, and interactions between, these markers.

RESULTS

Metabolic balance maps intuitively depicted the metabolic disruption of cardiovascular-related markers after AMI. The deviation and magnitude of the disruption were quantitatively and integrally described by φ and k (the dynamic parameter of metabolic balance disruption), respectively. The metabolic balance was disturbed in both the circulatory system and the heart post-AMI. All of the measured markers appeared to be interactional. Among these markers, kidney function and dimethylarginine dimethylaminohydrolase (DDAH) activity in the heart showed a potent effect on the other markers, whereas asymmetric dimethylarginine (ADMA) levels in plasma and adenosine triphosphate (ATP) contents in the heart were susceptible to the effects of the other markers.

CONCLUSION

A metabolic balance model was developed to integrally evaluate the disruption of cardiovascular-related markers after AMI, which proposes a new method for evaluating the disease state post-AMI using a multimarker approach. The unveiled interactions between these cardiovascular-related markers are helpful in understanding the pathophysiological processes.

Drug discovery for hyperuricemia

Hyperuricemia is associated with an increased risk of developing gout. This increases with the degree and duration of hyperuricemia. Gout can be managed by dietary modification and pharmacologic urate-lowering therapies. The recent identification of the renal apical urate/anion exchanger URAT1 (SLC22A12) and several membrane proteins relevant to the transport of urate play an important role in gaining a better understanding of the mode of action of many drugs used to treat gout. As described in this review, therapeutics designed to modify URAT1 transport activities might be useful in treating pathologies associated with hyperuricemia such as gout and urolithiasis. Continuing studies into the urate transportsome hold promise for the development of new, more effective therapeutics for hyperuricemia.

Comorbidity burden, healthcare resource utilization, and costs in chronic gout patients refractory to conventional urate-lowering therapy

Patients with chronic gout refractory to conventional urate-lowering therapy have high rates of flares and incidence of tophi, which impose a significant disease and potentially economic burden. This study examined healthcare resource use and costs stratified by disease burden. Adult patients diagnosed with gout (ICD-9-CM:274.xx) and having had ≥3 flares defined by clinical surrogates within a 12-month period were selected for the case cohort from the Thomson MarketScan databases (2003/Q3-2008/Q3). Only patients who had received allopurinol treatment and a diagnosis of tophi (ICD-9-CM:274.8x) at any time before the first flare (index date) or within 12 months postindex were included and were matched in a 1:1 ratio with control gout-free subjects. The comorbidity burden, healthcare resource use, and annual healthcare costs (2008 US$) in the 12-month postindex period were compared between both cohorts using regression models adjusted for demographic characteristic and stratified for patients with ≥6 flares. A total of 679 gout patients met the inclusion criteria for the study and had a higher prevalence of comorbidities than their matched controls. Gout cohort had a significantly higher incidence of emergency room, hospitalizations, outpatient visits, and other medical services than did their matched controls (all comparisons, uncorrected P < 0.01). After adjusting for baseline characteristics, the refractory gout cohort incurred an incremental total annual healthcare cost of $10,222 where 40% of the annual medical cost was for gout-related care compared with control cohort (P < 0.01). Patients with refractory gout have a significant economic burden compared with a gout-free population.

Dietary, anthropometric, and biochemical determinants of uric acid in free-living adults

BACKGROUND

High plasma uric acid (UA) is a prerequisite for gout and is also associated with the metabolic syndrome and its components and consequently risk factors for cardiovascular diseases. Hence, the management of UA serum concentrations would be essential for the treatment and/or prevention of human diseases and, to that end, it is necessary to know what the main factors that control the uricemia increase. The aim of this study was to evaluate the main factors associated with higher uricemia values analyzing diet, body composition and biochemical markers.

METHODS

415 both gender individuals aged 21 to 82 years who participated in a lifestyle modification project were studied. Anthropometric evaluation consisted of weight and height measurements with later BMI estimation. Waist circumference was also measured. The muscle mass (Muscle Mass Index - MMI) and fat percentage were measured by bioimpedance. Dietary intake was estimated by 24-hour recalls with later quantification of the servings on the Brazilian food pyramid and the Healthy Eating Index. Uric acid, glucose, triglycerides (TG), total cholesterol, urea, creatinine, gamma-GT, albumin and calcium and HDL-c were quantified in serum by the dry-chemistry method. LDL-c was estimated by the Friedewald equation and ultrasensitive C-reactive protein (CRP) by the immunochemiluminiscence method. Statistical analysis was performed by the SAS software package, version 9.1. Linear regression (odds ratio) was performed with a 95% confidence interval (CI) in order to observe the odds ratio for presenting UA above the last quartile (♂UA > 6.5 mg/dL and ♀ UA > 5 mg/dL). The level of significance adopted was lower than 5%.

RESULTS

Individuals with BMI ≥ 25 kg/m2 OR = 2.28(1.13-4.6) and lower MMI OR = 13.4 (5.21-34.56) showed greater chances of high UA levels even after all adjustments (gender, age, CRP, gamma-gt, LDL, creatinine, urea, albumin, HDL-c, TG, arterial hypertension and glucose). As regards biochemical markers, higher triglycerides OR = 2.76 (1.55-4.90), US-CRP OR = 2.77 (1.07-7.21) and urea OR = 2.53 (1.19-5.41) were associated with greater chances of high UA (adjusted for gender, age, BMI, waist circumference, MMI, glomerular filtration rate, and MS). No association was found between diet and UA.

CONCLUSIONS

The main factors associated with UA increase were altered BMI (overweight and obesity), muscle hypotrophy (MMI), higher levels of urea, triglycerides, and CRP. No dietary components were found among uricemia predictors.

Changes in uric acid levels following bariatric surgery are not associated with SLC2A9 variants in the Swedish Obese Subjects Study

Context and Objective

Obesity and SLC2A9 genotype are strong determinants of uric acid levels. However, data on SLC2A9 variants and weight loss induced changes in uric acid levels are missing. We examined whether the changes in uric acid levels two- and ten-years after weight loss induced by bariatric surgery were associated with SLC2A9 single nucleotide polymorphisms (SNPs) in the Swedish Obese Subjects study.

Methods

SNPs (N = 14) identified by genome-wide association studies and exonic SNPs in the SLC2A9 gene locus were genotyped. Cross-sectional associations were tested before (N = 1806), two (N = 1664) and ten years (N = 1201) after bariatric surgery. Changes in uric acid were compared between baseline and Year 2 (N = 1660) and years 2 and 10 (N = 1172). A multiple testing corrected threshold of P = 0.007 was used for statistical significance.

Results

Overall, 11 of the 14 tested SLC2A9 SNPs were significantly associated with cross-sectional uric acid levels at all three time points, with rs13113918 showing the strongest association at each time point (R² = 3.7−5.2%, 3.9×10⁻²²≤p≤7.7×10⁻¹¹). One SNP (rs737267) showed a significant association (R² = 0.60%, P = 0.002) with change in uric acid levels from baseline to Year 2, as common allele homozygotes (C/C, N = 957) showed a larger decrease in uric acid (−61.4 µmol/L) compared to minor allele carriers (A/X: −51.7 µmol/L, N = 702). No SNPs were associated with changes in uric acid from years 2 to 10.

Conclusions

SNPs in the SLC2A9 locus contribute significantly to uric acid levels in obese individuals, and the associations persist even after considerable weight loss due to bariatric surgery. However, we found little evidence for an interaction between genotype and weight change on the response of uric acid to bariatric surgery over ten years. Thus, the fluctuations in uric acid levels among the surgery group appear to be driven by the weight losses and gains, independent of SLC2A9 genotypes.

Safety of urate-lowering therapies: managing the risks to gain the benefits

Gout is a metabolic disorder of purine metabolism and uric acid elimination. Over time, acute gout can develop into a chronic, disabling arthropathy, often associated with multiple comorbidities. Gout patients have often been undertreated, partly because of the clinician's perceived risks of a therapy outweighing its potential benefits. The approval of new therapies to treat hyperuricemia in gout has led to a new understanding of gout management and medication safety regarding new and old therapies. This review focuses on potential safety issues of currently available urate-lowering therapies and outlines strategies to minimize risks so their benefits can be reached.

Efficacy and Tolerability of Celecoxib in the Treatment of Acute Gouty Arthritis: A Randomized Controlled Trial

Objective.

To evaluate the analgesic efficacy of high-dose celecoxib in the treatment of moderate to extreme pain and inflammation associated with acute gouty arthritis.

Methods.

A multinational, randomized, double-blind, double-dummy, active-controlled trial was done with patients (aged ≥ 18 years) with acute gouty monoarthritis or oligoarthritis (onset of pain ≤ 48 h before enrollment). Patients were treated for 8 days with 1 week followup and were randomized 1:1:1:1 to receive celecoxib 50 mg bid, celecoxib 400 mg (followed by 200 mg later on Day 1 and then 200 mg bid for 7 days), celecoxib 800 mg (followed by 400 mg later on Day 1 and then 400 mg bid for 7 days), or indomethacin 50 mg tid.

Results.

Of 443 patients screened, 402 were randomized and 400 received treatment. Baseline demographics were comparable among treatments. Patients receiving high-dose celecoxib (800/400 mg) experienced a significantly greater reduction in pain intensity on Day 2 compared with low-dose celecoxib 50 mg bid [least squares (LS) mean difference −0.46; p = 0.0014]. For high-dose celecoxib 800/400 mg, the change in pain scores from baseline to Day 2 was comparable with indomethacin 50 mg tid (LS mean difference 0.11; p = 0.4331). There were significant differences in adverse events when the combined celecoxib groups (29.5%) were compared with patients taking indomethacin (43.1%; p = 0.0116). There was no change in median serum creatinine levels for any treatment. There were more discontinuations due to adverse events (8.8% vs 3%; p = 0.0147) with indomethacin than with the combined celecoxib groups.

Conclusion.

High-dose celecoxib (800/400 mg) was significantly more effective than low-dose celecoxib (50 mg bid) and comparable to indomethacin in the treatment of moderate to extreme pain in patients with acute gouty arthritis. Further, celecoxib was well tolerated.

The role of high-protein diets in body weight management and health

Studies examining the health benefits of high-protein diets typical of most affluent and many developing countries are not consistent. Prospective epidemiological studies relating dietary protein to clinical and metabolic endpoints suggest increased weight gain and increased risk of diabetes amongst those with a high protein intake and an increased risk of cancer with high intakes of red meat, but lower blood pressure and possibly a reduced risk of heart disease with higher protein intakes. The potential for high-protein diets to confer greater benefit than other diets has been examined using ad libitum and energy restricted diets. Of greatest interest have been the comparisons between high-protein and high-carbohydrate diets. Many trials have reported greater weight loss especially in the context of ad libitum diets over the short-to medium-term, sparing of lean body mass, lowering of triglyceride levels, improved HDL: total cholesterol ratio and improved glycaemic control. Limited data regarding insulin sensitivity are less consistent. A major difficulty in interpreting the results of these studies is that carbohydrate quality has not been taken into account. Furthermore, longer term comparisons of weight reducing diets differing in macronutrient composition have reported similar outcomes, suggesting that compliance is a more important consideration. Nevertheless dietary patterns with high-protein intakes are appropriate for weight reduction and weight maintenance and may be useful for those who have high triglyceride levels and other features of the metabolic syndrome.

HLA-B*58:01 allele is associated with augmented risk for both mild and severe cutaneous adverse reactions induced by allopurinol in Han Chinese

Aim: Allopurinol is widely used as an effective urate-lowering drug and is one of the most frequent causes of cutaneous adverse drug reactions (cADRs). Recently, a strong association of HLA-B*58:01 with allopurinol-induced severe cADRs was identified. This study investigated the predisposition to different types of allopurinol-cADRs conferred by HLA-B*5801 in a Han population from mainland China. Patients & methods:HLA-B genotyping was performed on 38 Chinese patients with different types of allopurinol-cADRs from 2008 to 2011. Results: All the allopurinol-cADR patients carried HLA-B*58:01, in contrast with only 11.11% (7/63) in the allopurinol-tolerant patients (odds ratio [OR] = 580.07; p < 0.0001) and 13.99% (80/572) in a Han Chinese population from the human MHC database (dbMHC; OR: 471.09; p < 0.0001) carried the genotype. Each type of allopurinol cADRs revealed a statistically significant association with HLA-B*58:01. In particular, the risk of allopurinol-induced maculopapular eruption was significantly higher in patients with HLA-B*58:01 (OR: 339.00; p < 0.0001). Conclusion: The strong association of both the mild and severe types of allopurinol cADRs with the HLA-B*58:01 allele were observed. The results indicated that the prospective use of a genetic test of HLA-B*58:01 might reduce the prevalence of allopurinol-induced cADRs.

Original submitted 7 March 2012; Revision submitted 21 May 2012

Purine-rich foods intake and recurrent gout attacks

OBJECTIVE

To examine and quantify the relation between purine intake and the risk of recurrent gout attacks among gout patients.

METHODS

The authors conducted a case-crossover study to examine associations of a set of putative risk factors with recurrent gout attacks. Individuals with gout were prospectively recruited and followed online for 1 year. Participants were asked about the following information when experiencing a gout attack: the onset date of the gout attack, clinical symptoms and signs, medications (including antigout medications), and presence of potential risk factors (including daily intake of various purine-containing food items) during the 2-day period prior to the gout attack. The same exposure information was also assessed over 2-day control periods.

RESULTS

This study included 633 participants with gout. Compared with the lowest quintile of total purine intake over a 2-day period, OR of recurrent gout attacks were 1.17, 1.38, 2.21 and 4.76, respectively, with each increasing quintile (p for trend <0.001). The corresponding OR were 1.42, 1.34, 1.77 and 2.41 for increasing quintiles of purine intake from animal sources (p for trend <0.001), and 1.12, 0.99, 1.32 and 1.39 from plant sources (p=0.04), respectively. The effect of purine intake persisted across subgroups by sex, use of alcohol, diuretics, allopurinol, NSAIDs and colchicine.

CONCLUSIONS

The study findings suggest that acute purine intake increases the risk of recurrent gout attacks by almost fivefold among gout patients. Avoiding or reducing amount of purine-rich foods intake, especially of animal origin, may help reduce the risk of gout attacks.

Association between HLA-B*58:01 allele and severe cutaneous adverse reactions with allopurinol in Han Chinese in Hong Kong

BACKGROUND

Allopurinol has been reported as a common cause of severe cutaneous adverse reactions (SCARs). Recent studies in various populations suggest that HLA-B*58:01 is a strong genetic marker for allopurinol-induced SCAR, especially in populations with a high frequency of HLA-B*58:01.

OBJECTIVES

To confirm the association link between HLA-B*58:01 and hypersensitivity reactions attributed to allopurinol use in Han Chinese patients in Hong Kong.

METHODS

We performed a case-control study to investigate whether the HLA-B*58:01 allele predisposes to allopurinol-induced SCAR in Han Chinese patients in Hong Kong. The HLA-B*58:01 genotyping was performed in 20 patients with allopurinol-induced SCAR or erythema multiforme major (EMM; n = 1) and in 30 patients tolerant to allopurinol.

RESULTS

All of the 19 patients with allopurinol-induced SCAR examined but not the patient with EMM carried HLA-B*58:01 whereas only four (13%) of the control patients had this allele. The positive rate of the HLA-B*58:01 was significantly higher in the cases than in the allopurinol-tolerant control group [odds ratio (OR) 123·5, 95% confidence interval (CI) 12·8-1195·1; P < 1 × 10(-4) ] and was even higher after removal of the patient with EMM (OR 229·7, 95% CI 11·7-4520·4). The sensitivity and specificity of the HLA-B*58:01 allele for prediction of allopurinol-induced SCAR were 100% and 86·7%, respectively.

CONCLUSIONS

This study confirmed the strong association between the HLA-B*58:01 and allopurinol-induced SCAR in Hong Kong Han Chinese patients. A screening test for the HLA-B*58:01 allele should effectively reduce the risk for allopurinol-induced SCAR in Chinese populations.

High plasma uric acid concentration: causes and consequences

High plasma uric acid (UA) is a precipitating factor for gout and renal calculi as well as a strong risk factor for Metabolic Syndrome and cardiovascular disease. The main causes for higher plasma UA are either lower excretion, higher synthesis or both. Higher waist circumference and the BMI are associated with higher insulin resistance and leptin production, and both reduce uric acid excretion. The synthesis of fatty acids (tryglicerides) in the liver is associated with the de novo synthesis of purine, accelerating UA production. The role played by diet on hyperuricemia has not yet been fully clarified, but high intake of fructose-rich industrialized food and high alcohol intake (particularly beer) seem to influence uricemia. It is not known whether UA would be a causal factor or an antioxidant protective response. Most authors do not consider the UA as a risk factor, but presenting antioxidant function. UA contributes to > 50% of the antioxidant capacity of the blood. There is still no consensus if UA is a protective or a risk factor, however, it seems that acute elevation is a protective factor, whereas chronic elevation a risk for disease.

Allopurinol as a cardiovascular drug

Cardiovascular disease (CVD) remains the leading cause of death in the United States. There is evidence that shows a direct relationship between an elevated uric acid level and an increased risk of cardiovascular (CV) events, which has set the foundation for the investigation of uric acid-lowering drugs for the treatment of CVD. Although traditionally the cornerstone therapy for gout, allopurinol's ability to be a competitive inhibitor of the key enzyme, xanthine oxidase, needed for uric acid formation, has prompted recent clinical research evaluating allopurinol as a CV drug. Epidemiologic and biochemical studies on uric acid formation have shown that it is not only uric acid itself that leads to worsening prognosis and increased CV events, but also the free radicals and superoxides formed during xanthine oxidase activity. The combination of uric acid formation and formed free radicals could ultimately lead to coronary endothelial dysfunction and worsening of myocardial oxidative stress. Along with preventing uric acid formation, allopurinol also has the ability to behave as a free radical scavenger of the superoxide anions and free radicals released during uric acid formation.Clinical studies have shown that allopurinol improves endothelial dysfunction and subsequently improves the exercise capacity in patients diagnosed with angina pectoris. Allopurinol has also been shown to decrease oxidative stress and ameliorate the morbidity and mortality of congestive heart failure patients by possibly improving mechanoenergetic uncoupling, with the enhancement of myocardial contractility and the left ventricular ejection fraction. This review presents the pharmacologic action of allopurinol on the CV system and describes the effectiveness of allopurinol as a potential drug to treat 2 CVD morbidities: ischemic heart disease and congestive heart failure.

Novel evidence-based colchicine dose-reduction algorithm to predict and prevent colchicine toxicity in the presence of cytochrome P450 3A4/P-glycoprotein inhibitors

OBJECTIVE

Drug-drug interactions can limit the safety of colchicine for treating rheumatic diseases. Seven separate drug-drug interaction (DDI) studies were performed to elucidate the in vivo effects of concomitant treatment with colchicine and known inhibitors of cytochrome P450 3A4 (CYP3A4)/P-glycoprotein (cyclosporine, ketoconazole, ritonavir, clarithromycin, azithromycin, verapamil ER [extended release]), and diltiazem ER) on the pharmacokinetics of colchicine. The objective was to develop colchicine-dosing algorithms with improved safety.

METHODS

All studies were open-label, non-randomized, single-center, one-sequence, two-period DDI experiments, using two 0.6-mg doses of colchicine, separated by a minimum 14-day washout period, followed by administration of the approved on-label regimen of known CYP3A4/P-glycoprotein inhibitors. Plasma concentrations of colchicine, but not the reference CYP3A4/P-glycoprotein inhibitors, were determined, and the pharmacokinetic parameters were calculated.

RESULTS

The ratios of the maximum concentration and area under the curve from time 0 to infinity for colchicine plus CYP3A4/P-glycoprotein inhibitors versus colchicine alone were >125% across all studies, with the exception of studies involving azithromycin. Significant DDIs were present when single doses of colchicine were coadministered with most of the selected CYP3A4/P-glycoprotein inhibitors. Recommended colchicine dose reductions of 33-66% for the treatment of acute gout and 50-75% for prophylaxis were calculated for concomitant therapy with each agent, with the exception of no dose adjustment when colchicine is used in combination with azithromycin.

CONCLUSION

These studies provide quantitative evidence regarding drug interactions and necessary adjustments in the dose of colchicine if colchicine treatment is continued during therapy with multiple CYP3A4/P-glycoprotein inhibitors. We demonstrated the need for specific reductions in the dose of colchicine when it is used in combination with 2 broadly prescribed calcium channel blockers (verapamil ER and diltiazem ER) and that the dose of colchicine does not need to be adjusted when it is used in combination with azithromycin.

The epidemiology of uric acid and fructose

During the past few decades, the mean serum uric acid levels and the prevalence of hyperuricemia in the general population appear to have increased. Correspondingly, the prevalence and incidence of gout have doubled. Potential reasons behind these trends include the increasing prevalence of obesity and metabolic syndrome, Western lifestyle factors, increased prevalence of medical conditions (eg, renal conditions, hypertension, and cardiovascular disorders), and use of medications that increase uric acid levels (eg, diuretics and low-dose aspirin). The substantial increase in sugar-sweetened soft drinks and associated fructose consumption also has coincided with the secular trend of hyperuricemia and gout. Recently, several large-scale epidemiologic studies have clarified a number of these long-suspected risk factors in relation with hyperuricemia and gout. Furthermore, recent studies have illuminated the substantial comorbidities of hyperuricemia and gout, particularly metabolic-cardiovascular-renal conditions. Although many prospective studies have suggested an independent association between serum uric acid levels and the future risk of cardiovascular-metabolic morbidities and mortality, only a limited number of randomized clinical trials and observational studies recently have shown that the use of allopurinol can be beneficial against these outcomes. Because these data are scarce and the effects of allopurinol might not be limited to decreasing serum uric acid levels, the potential causal role of uric acid on these outcomes remains to be clarified with further studies.

Longitudinal tears of peroneus longus and brevis tendons: a gouty infiltration

The natural history of recurrent uric acid deposition includes joint destruction, as well as tendon weakening and rupture. Simultaneous rupture of the peroneus longus and brevis tendons secondary to tophaceous gout is very rare. In the present report, we describe the case of a 37-year-old man who had a history of recurrent ankle pain and 4 previous episodes of acute gout localized to his ipsilateral first metatarsophalangeal joint. The physical examination revealed the ankle pain to actually be localized to the peroneal tendons immediately distal to the fibular malleolar groove. Magnetic resonance imaging showed longitudinal tears in the peroneus longus and brevis. Surgical exploration and repair of the ruptured tendons revealed the presence of monosodium urate deposition within the substance of the tendons at the rupture sites. The tendons were debrided and repaired using longus to brevis tenodesis. The postoperative course was unremarkable and entailed referral to a rheumatologist for metabolic management. After more than a 1-year period of follow-up, the patient was ambulating without difficulties wearing regular shoe gear.

Allopurinol to Febuxostat: How far have we come?

For decades allopurinol has been used as a xanthine oxidase inhibitor for treatment of hyperuricemia and gout. Although effective in many patients, some experience sensitivity to the drug. In some cases, this sensitivity may lead to allopurinol hypersensitivity disorder, which if untreated can be fatal. Recently the Food and Drug Administration has approved the use of febuxostat as an alternative therapy for hyperuricemia and gout. Febuxostat is a new xanthine oxidase inhibitor, but is not purine based and therefore decreases adverse reactions due to patient sensitivity. This review is a comprehensive look at the background of hyperuricemia and gout treatment with allopurinol compared to recent clinical studies with febuxostat. Each clinical study is evaluated and summarized, identifying the advances in treatment that have been made as well as the concerns that still exist with either treatment.

Role of diet in rheumatic disease

Millions of people suffer from rheumatic diseases such as gout, fibromyalgia, osteoarthritis, and rheumatoid arthritis. These can be incapacitating and detrimental to quality of life. Diet, nutrition, and weight loss have shown promise in alleviating some of this disease burden. These lifestyle changes may give patients a feeling of control and ownership over their disease as well as a nonpharmacologic means of treatment. This article reviews the available research on the effects of diet and nutrition on rheumatoid disease.

Synthesis and xanthine oxidase inhibitory activity of 7-methyl-2-(phenoxymethyl)-5H-[1,3,4]thiadiazolo[3,2-a]pyrimidin-5-one derivatives

An elevated level of blood uric acid (hyperuricemia) is the underlying cause of gout. Xanthine oxidase is the key enzyme that catalyzes the oxidation of hypoxanthine to xanthine and then to uric acid. Allopurinol, a widely used xanthine oxidase inhibitor is the most commonly used drug to treat gout. However, a small but significant portion of the population suffers from adverse effects of allopurinol that includes gastrointestinal upset, skin rashes and hypersensitivity reactions. Moreover, an elevated level of uric acid is considered as an independent risk factor for cardiovascular diseases. Therefore use of allopurinol-like drugs with minimum side effects is the ideal drug of choice against gout. In this study, we report the synthesis of a series of pyrimidin-5-one analogues as effective and a new class of xanthine oxidase inhibitors. All the synthesized pyrimidin-5-one analogues are characterized by spectroscopic techniques and elemental analysis. Four (6a, 6b, 6d and 6f) out of 20 synthesized molecules in this class showed good inhibition against three different sources of xanthine oxidase, which were more potent than allopurinol based on their respective IC(50) values. Molecular modeling and docking studies revealed that the molecule 6a has very good interactions with the Molybdenum-Oxygen-Sulfur (MOS) complex a key component in xanthine oxidase. These results highlight the identification of a new class of xanthine oxidase inhibitors that have potential to be more efficacious, than allopurinol, to treat gout and possibly against cardiovascular diseases.

Human sodium phosphate transporter 4 (hNPT4/SLC17A3) as a common renal secretory pathway for drugs and urate

The evolutionary loss of hepatic urate oxidase (uricase) has resulted in humans with elevated serum uric acid (urate). Uricase loss may have been beneficial to early primate survival. However, an elevated serum urate has predisposed man to hyperuricemia, a metabolic disturbance leading to gout, hypertension, and various cardiovascular diseases. Human serum urate levels are largely determined by urate reabsorption and secretion in the kidney. Renal urate reabsorption is controlled via two proximal tubular urate transporters: apical URAT1 (SLC22A12) and basolateral URATv1/GLUT9 (SLC2A9). In contrast, the molecular mechanism(s) for renal urate secretion remain unknown. In this report, we demonstrate that an orphan transporter hNPT4 (human sodium phosphate transporter 4; SLC17A3) was a multispecific organic anion efflux transporter expressed in the kidneys and liver. hNPT4 was localized at the apical side of renal tubules and functioned as a voltage-driven urate transporter. Furthermore, loop diuretics, such as furosemide and bumetanide, substantially interacted with hNPT4. Thus, this protein is likely to act as a common secretion route for both drugs and may play an important role in diuretics-induced hyperuricemia. The in vivo role of hNPT4 was suggested by two hyperuricemia patients with missense mutations in SLC17A3. These mutated versions of hNPT4 exhibited reduced urate efflux when they were expressed in Xenopus oocytes. Our findings will complete a model of urate secretion in the renal tubular cell, where intracellular urate taken up via OAT1 and/or OAT3 from the blood exits from the cell into the lumen via hNPT4.

COlchicine for the Prevention of the Post-pericardiotomy Syndrome (COPPS): a multicentre, randomized, double-blind, placebo-controlled trial

AIMS

No drug has been proven efficacious to prevent the post-pericardiotomy syndrome (PPS), but colchicine seems safe and effective for the treatment and prevention of pericarditis. The aim of the COlchicine for the Prevention of the Post-pericardiotomy Syndrome (COPPS) trial is to test the efficacy and safety of colchicine for the primary prevention of the PPS.

METHODS AND RESULTS

The COPPS study is a multicentre, double-blind, randomized trial. On the third post-operative day, 360 patients (mean age 65.7 ± 12.3 years, 66% males), 180 in each treatment arm, were randomized to receive placebo or colchicine (1.0 mg twice daily for the first day followed by a maintenance dose of 0.5 mg twice daily for 1 month in patients ≥70 kg, and halved doses for patients <70 kg or intolerant to the highest dose). The primary efficacy endpoint was the incidence of PPS at 12 months. Secondary endpoint was the combined rate of disease-related hospitalization, cardiac tamponade, constrictive pericarditis, and relapses. Baseline characteristics were well balanced between the study groups. Colchicine significantly reduced the incidence of the PPS at 12 months compared with placebo (respectively, 8.9 vs. 21.1%; P = 0.002; number needed to treat = 8). Colchicine also reduced the secondary endpoint (respectively, 0.6 vs. 5.0%; P = 0.024). The rate of side effects (mainly related to gastrointestinal intolerance) was similar in the colchicine and placebo groups (respectively, 8.9 vs. 5.0%; P = 0.212).

CONCLUSION

Colchicine is safe and efficacious in the prevention of the PPS and its related complications and may halve the risk of developing the syndrome following cardiac surgery. ClinicalTrials.gov number, NCT00128427.

The serum urate-lowering impact of weight loss among men with a high cardiovascular risk profile: the Multiple Risk Factor Intervention Trial

OBJECTIVES

To evaluate the person-level impact of weight loss on serum urate levels among men with a high cardiovascular risk profile.

METHODS

We analysed 12,379 men (mean serum urate level=407 μmol/l) from the Multiple Risk Factor Intervention Trial, using data prospectively collected at baseline and annually over a 7-year period (78,881 visits). Our endpoint was normouricaemia, defined by serum urate levels≤360 μmol/l, a widely accepted therapeutic target. Person-level effects were estimated using conditional logistic regression models to adjust for time-varying covariates (age, congestive heart failure, hypertension, diuretic use, renal function, alcohol intake and dietary factors).

RESULTS

There was a graded relation between weight loss and achieving normouricaemia (P-value for trend<0.001). Compared with no weight change (-0.9 to 0.9 kg), the multivariate odds ratios of achieving normouricaemia for a weight loss of 1-4.9, 5-9.9 and ≥10 kg were 1.43 (95% CI: 1.33, 1.54), 2.17 (1.95, 2.40) and 3.90 (3.31, 4.61), respectively. The corresponding serum urate level changes were -7, -19 and -37 μmol/l (-0.12, -0.31 and -0.62 mg/dl). Similar levels of associations persisted among subgroups stratified by demographics, presence of gout, hypertension, diuretic use, renal insufficiency, alcohol intake, trial group assignment and adiposity categories (all P-values for trend<0.001).

CONCLUSIONS

Weight reduction could help achieve a widely accepted therapeutic urate target level (≤360 μmol/l) among men with a high cardiovascular risk profile. Although the urate-lowering effect appeared weaker than that of urate-lowering drugs, other associated health benefits would make weight reduction important, particularly in this population.

High levels of serum uric acid are associated with silent brain infarction

BACKGROUND

Uric acid has been known to exert neuroprotective effects by acting as a free radical scavenger; however, several observational studies indicated that high levels of serum uric acid increased the risk of cardiovascular events or stroke. We sought to determine whether increased levels of uric acid are associated with the presence of silent brain infarction (SBI).

METHODS

We recruited a consecutive series of non-stroke individuals who visited the Healthcare System in our hospital and underwent brain MRI (n=1577). We conducted intensive interviews and laboratory examinations, including serum uric acid. We examined associations between SBI and vascular risk factors including uric acid by controlling possible confounders.

RESULTS

Of the 1577 subjects recruited, 921 were men and 656 were women, and the uric acid level was much higher in the men (6.3±1.3) than in the women (4.7±1.0). There was a strong dose-response relationship between the quartiles of uric acid and the presence of SBI in women (p=0.001), but not in men. Multivariable analysis showed that the highest quartile of uric acid level was an independent risk factor for the presence of SBI in total patients (adjusted OR, 1.79; 95% CI, 1.11-2.91). However, this association remained significant in women (adjusted OR, 2.64; 95% CI, 1.17-5.91), but not in men.

CONCLUSIONS

Our results suggest that an increased level of uric acid may be a risk factor for the presence of SBI. Serum uric acid level might be a good serum marker of underlying SBI or future stroke, especially in women.

Treatment of chronic tophaceous gout with a wound vacuum-assisted device

Level of Evidence: V, Expert Opinion

Febuxostat: the evidence for its use in the treatment of hyperuricemia and gout

Introduction:

Gout is a common and disabling cause of arthritis in middle-aged and elderly populations, with its main predisposing factor being hyperuricemia (serum urate > 6.8 mg/dL). Options for treatment of chronic gout until 2008 were allopurinol, a xanthine oxidase inhibitor, and the group of drugs known as uricosurics that stimulate the renal excretion of uric acid. A proportion of patients, including some with chronic kidney disease and solid organ transplantations, could not be treated with the those therapies because of intolerance, drug interactions, or adverse events. Febuxostat is a nonpurine xanthine oxidase inhibitor, recently approved in Europe and the United States for the treatment of chronic gout.

Aim:

To review the clinical evidence (phase II and III studies) of the effectiveness and safety of febuxostat for treatment of hyperuricemia and gout.

Evidence review:

Febuxostat, at doses ranging from 40 to 240 mg/day, is efficacious in reducing serum urate in patients with hyperuricemia and gout, comparing favorably with fixed doses of allopurinol in that respect. Early safety signals with respect to liver test abnormalities and cardiovascular outcomes have not been confirmed in recent large prospective trials but need to be further monitored.

Clinical potential:

Given its low cost and extensive clinical experience, allopurinol will likely remain the first-line drug for management of hyperuricemia and gout. Febuxostat may provide an important option in patients unable to use allopurinol, those with very high serum urate levels, or in the presence of refractory tophi.

Colchicine for the treatment of pericarditis

Colchicine has been effectively used in the treatment of several inflammatory conditions, such as gouty attacks, serositis related to familial Mediterranean fever, Behçet syndrome and more recently, in acute and recurrent pericarditis. Colchicine concentrates in white blood cells, particularly polymorphonuclear cells, inhibiting tubulin polymerization, thus interfering with migration and phagocytosis, and reducing the inflammatory cycle. Although the exact number of responders is unknown, the drug has been successfully used for the treatment and prevention of recurrences and to taper corticosteroids in patients with recurrent pericarditis in several retrospective studies and an open-label, randomized trial, where the recurrence rate was halved in the treatment arm. Less evidence supports the use of the drug for the treatment of acute pericarditis, where colchicine remains optional and requires further multicenter confirmatory studies. At present, colchicine has been recommended by the 2004 European guidelines on the management of pericardial diseases for acute (class IIa) and recurrent pericarditis (class I), but its use is still unlabeled and informed consent is required for prescription. A careful monitoring of possible contraindications, drug interactions and side effects is necessary. The aim of this paper is to review the evidence that supports the use of the drug in acute and recurrent pericarditis, as well as dosing and precautions for clinical use.

High versus low dosing of oral colchicine for early acute gout flare: Twenty-four-hour outcome of the first multicenter, randomized, double-blind, placebo-controlled, parallel-group, dose-comparison colchicine study

OBJECTIVE

Despite widespread use of colchicine, the evidence basis for oral colchicine therapy and dosing in acute gout remains limited. The aim of this trial was to compare low-dose colchicine (abbreviated at 1 hour) and high-dose colchicine (prolonged over 6 hours) with placebo in gout flare, using regimens producing comparable maximum plasma concentrations in healthy volunteers.

METHODS

This multicenter, randomized, double-blind, placebo-controlled, parallel-group study compared self-administered low-dose colchicine (1.8 mg total over 1 hour) and high-dose colchicine (4.8 mg total over 6 hours) with placebo. The primary end point was > or = 50% pain reduction at 24 hours without rescue medication.

RESULTS

There were 184 patients in the intent-to-treat analysis. Responders included 28 of 74 patients (37.8%) in the low-dose group, 17 of 52 patients (32.7%) in the high-dose group, and 9 of 58 patients (15.5%) in the placebo group (P = 0.005 and P = 0.034, respectively, versus placebo). Rescue medication was taken within the first 24 hours by 23 patients (31.1%) in the low-dose group (P = 0.027 versus placebo), 18 patients (34.6%) in the high-dose group (P = 0.103 versus placebo), and 29 patients (50.0%) in the placebo group. The low-dose group had an adverse event (AE) profile similar to that of the placebo group, with an odds ratio (OR) of 1.5 (95% confidence interval [95% CI] 0.7-3.2). High-dose colchicine was associated with significantly more diarrhea, vomiting, and other AEs compared with low-dose colchicine or placebo. With high-dose colchicine, 40 patients (76.9%) had diarrhea (OR 21.3 [95% CI 7.9-56.9]), 10 (19.2%) had severe diarrhea, and 9 (17.3%) had vomiting. With low-dose colchicine, 23.0% of the patients had diarrhea (OR 1.9 [95% CI 0.8-4.8]), none had severe diarrhea, and none had vomiting.

CONCLUSION

Low-dose colchicine yielded both maximum plasma concentration and early gout flare efficacy comparable with that of high-dose colchicine, with a safety profile indistinguishable from that of placebo.

Epidemiology of gout in women: Fifty-two-year followup of a prospective cohort

OBJECTIVE

Despite the recent doubling of the incidence of gout among women and its substantial prevalence particularly in the aging female population, the risk factors for gout among women remain unknown. We undertook this study to evaluate purported risk factors for incident gout among women and to compare them with those among men.

METHODS

Using prospective data from the Framingham Heart Study, we examined over a 52-year period (1950-2002) the relationship between purported risk factors and the incidence of gout in 2,476 women and 1,951 men.

RESULTS

We documented 304 incident cases of gout, 104 of them among women. The incidence rates of gout for women per 1,000 person-years according to serum uric acid levels of <5.0, 5.0-5.9, 6.0-6.9, 7.0-7.9, and > or = 8.0 mg/dl were 0.8, 2.5, 4.2, 13.1, and 27.3, respectively (P for trend < 0.0001). The magnitude of this association was lower than that among men (P for interaction = 0.0002). Multivariate relative risks conferred by increasing age (per 5 years), obesity (body mass index > or = 30 kg/m(2)), alcohol intake (> or = 7 ounces of pure alcohol/week), hypertension, and diuretic use were 1.24, 2.74, 3.10, 1.82, and 2.39, respectively (all P < 0.05), for women.

CONCLUSION

These prospective data with long-term followup provide evidence that higher levels of serum uric acid increase the risk of gout in a graded manner among women, but the rate of increase is lower than that among men. Increasing age, obesity, alcohol consumption, hypertension, and diuretic use were associated with the risk of incident gout among women.

A survey on the management of gout in Malaysia

AIM

The aim of this study was to ascertain the management of gout by doctors in Malaysia.

METHODS

A cross-sectional questionnaire survey was carried out among doctors attending rheumatology post-graduate courses, where gout was not a lecture topic.

RESULTS

A total of 128 questionnaires were analyzed, of which the majority (67: 52.3%) were general practitioners. In the treatment of acute gout, 68.0% use non-selective non-steroidal anti-inflammatory drugs (NSAIDs), 53.9% use selective COX-2 inhibitors (coxibs), 66.4% use colchicine and 10.2% use allopurinol (ALLO). In the treatment of chronic gout, 36.7% use NSAIDs, 44.5% use coxibs, 19.5% use colchicine and 93% use ALLO. In both acute and chronic gout, corticosteroids (CS) are not used by over 90% of respondents. Fifty percent would stop ALLO during an acute attack. 95.3% do not start ALLO during an acute attack; 87.5% would start ALLO after the attack, with a median of 14 days afterwards. Once ALLO was started, 54.7% would continue indefinitely. Regarding target urate levels while on treatment, 10.9% would be satisfied with a high normal range, 21.9% middle of the range, 18.0% low normal range and 45.3% anywhere within the normal range. Fifteen percent would treat asymptomatic hyperuricemia.

CONCLUSIONS

In Malaysia, anti-inflammatory agents are most commonly used for the treatment of acute and chronic gout, with corticosteroid usage at a low level. However, there are areas of concern regarding the diagnosis of gout and the usage of ALLO which are not consistent with current guidelines.

Practical steps in the diagnosis and management of gout

One of the earliest described conditions, gout continues to plague humanity. It is characterised by the deposition of monosodium urate crystals in the joints and soft tissue. The main clinical features of gout are hyperuricaemia, acute monoarticular arthritis, tophi and chronic arthritis, along with nephrolithiasis. Gout typically occurs in middle age and more commonly in men. Asymptomatic hyperuricaemia does not require treatment. The initial attack of acute gout usually affects a single joint, often the first metatarsal phalangeal joint. Definitive diagnosis requires demonstration of urate crystals in the joint fluid. Treatment of acute gout includes nonsteroidal anti-inflammatory drugs (NSAIDs), colchicine and corticosteroids. The most important factor in success of treatment is how quickly therapy is begun after onset of symptoms. Drug treatment of hyperuricaemia includes allopurinol, sulfinpyrazone, probenecid and benzbromarone and should be used in patients with frequent gout attacks, tophi or urate nephropathy.

The variable clinical picture of drug-induced hypersensitivity syndrome/drug rash with eosinophilia and systemic symptoms in relation to the eliciting drug

Drug-induced hypersensitivity syndrome (DIHS)/drug rash with eosinophilia and systemic symptoms (DRESS) is a life-threatening adverse reaction characterized by skin rashes, fever, leukocytosis with eosinophilia or atypical lymphocytosis, lymph node enlargement, and liver or renal dysfunction. The syndrome develops 2 to 6 weeks after initiation of administration of a specific drug. It has been demonstrated that various herpesvirus reactivations, in addition to human herpesvirus 6, contribute to internal organ involvement and the relapse of symptoms observed long after discontinuation of the causative drugs. A better understanding of the interplay in the development of DIHS/DRESS has implications for safer and more efficient treatment of this syndrome.