A study of renal function of 51 patients with gout and an equal number of normouricaemic controls revealed significant differences. A relative impairment of the glomerular filtration rate and urine concentrating ability in the gouty subjects could not be wholly explained on the basis of aging or hypertension. Renal dysfunction was generally mild and was not associated with specific clinical characteristics higher levels of uric acid excretion, or hypertriglyceridaemia. Gout patients excreted urine with a significantly lower pH. This was associated with a relatively high excretion of titratable acid and a deficit of ammonium excretion, which was accentuated by ingestion of an acid load. Urate clearance was significantly reduced in gout, even when expressed as a fraction of the glomerular filtration rate.
Allopurinol (4-hydroxypyrazolo (3,4-d)-pyrimidine) is a potent xanthine oxidase inhibitor which inhibits the oxidation of naturally occurring oxypurines, thus decreasing uric acid formation. The clinical and metabolic effects of this agent were studied in 80 subjects with primary and secondary gout and other disorders of uric acid metabolism. Allopurinol has been universally successful in lowering the serum uric acid concentration and uric acid excretion to normal levels, while not significantly affecting the clearance of urate or other aspects of renal function. Oxypurine excretion increased concomitantly with the fall in urine uric acid. The agent is particularly valuable in the management of problems of gout with azotemia, acute uric acid nephropathy and uric acid urolithiasis. The minor side effects, clinical indications and theoretical complications are discussed.
Febuxostat is a novel, potent, non-purine selective xanthine oxidase inhibitor, which in clinical trials demonstrated superior ability to lower and maintain serum urate levels below 6 mg/dL compared with conventionally used doses of allopurinol. Febuxostat was well tolerated in long term treatment in patients with hyperuricemia including those experiencing hypersensitity/intolerance to allopurinol. Dose adjustment appears unnecessary in patients with mild to moderate renal or liver insufficiency or advanced age. The most common adverse reactions reported were abnormal liver function tests, headache, and gastrointestinal symptoms, which were usually mild and transient. However, whether hepatotoxicity becomes a limitation in the use of febuxostat needs to be determined in further studies. An increased frequency of gout flares occurs for a prolonged period after treatment initiation, as with any aggressive lowering of serum urate, and prolonged prophylaxis with colchicine or NSAIDs is usually required. Febuxostat has been granted marketing authorization by the European Commission in early 2008 for the treatment of chronic hyperuricemia and gout. Febuxostat is the first major treatment alternative for gout in more than 40 years and is a promising alternative to allopurinol, although continued long-term surveillance on safety and efficacy is required.
febuxostat; TEI-6720; TMX-67; gout; hyperuricemia; xanthine oxidase inhibitor
Gout recently passed rheumatoid arthritis to become the most common inflammatory arthritis in the United States (US). However, epidemiologic studies indicate that the quality of gout management is suboptimal owing to both patient and physician issues. Only three options for urate-lowering therapy are currently available in the US: allopurinol, probenecid, and recently, febuxostat. Probenecid is generally safe except for the occurrence of urolithiasis, but is only effective for the subset of patients with better kidney function. Allopurinol use is limited due to its side effects, potential toxicity of uncertain magnitude in patients with renal disease, and failure to achieve targeted serum urate levels. In part this failure may be due to the necessity for it to be titrated for optimal therapeutic effect. Febuxostat is a new medication that may offer several advantages and can be given as an alternative to allopurinol. We review the basic biology and clinical performance of febuxostat, and consider the potential utility of this agent in comparison to the older, better-established gout therapeutics.
allopurinol; gout suppressants; nephrolithiasis; uric acid; urolithiasis
The prevalence of gout is increasing with increased life expectancy. Approximately half of the patients with gout have some degree of renal impairment. If both conditions persistently coexist, and in severe tophaceous gout, in particular, treatment has been difficult. We here report on the case of an 87-year-old woman, who had been suffering from recurrent gouty arthritis over 4 years. Monthly polyarthritis attacks were accompanied by subcutaneous tophi. Serum uric acid levels were constantly above 600 μmol/L (10 mg/dL). Allopurinol was no option because of intolerance, while benzbromarone was ineffective because of renal impairment. Therefore, the novel xanthin oxidase inhibitor febuxostat was started, achieving rapid control of serum urate levels (<360 μmol/L). After initial worsening of inflammation in the first weeks, gouty attacks stopped and all tophi resolved within the following 10 months. Renal function remained stable.
African Americans are twice as likely as Caucasians to develop gout, but they are less likely to be treated with urate-lowering therapy (ULT). Furthermore, African Americans typically present with more comorbidities associated with gout, such as hypertension, obesity, and renal impairment. We determined the efficacy and safety of ULT with febuxostat or allopurinol in African American subjects with gout and associated comorbidities and in comparison to Caucasian gout subjects.
This is a secondary analysis of the 6-month Phase 3 CONFIRMS trial. Eligible gouty subjects with baseline serum urate (sUA) ≥ 8.0 mg/dL were randomized 1:1:1 to receive febuxostat 40 mg, febuxostat 80 mg, or allopurinol (300 mg or 200 mg depending on renal function) daily. All subjects received gout flare prophylaxis. Primary efficacy endpoint was the proportion of subjects in each treatment group with sUA < 6.0 mg/dL at the final visit. Additional endpoints included the proportion of subjects with mild or with moderate renal impairment who achieved a target sUA < 6.0 mg/dL at final visit. Adverse events (AEs) were recorded throughout the study.
Of the 2,269 subjects enrolled, 10.0% were African American and 82.1% were Caucasian. African American subjects were mostly male (89.5%), obese (BMI ≥ 30 kg/m2; 67.1%), with mean baseline sUA of 9.8 mg/dL and mean duration of gout of 10.4 years. The proportions of African American subjects with a baseline history of diabetes, renal impairment, or cardiovascular disease were significantly higher compared to Caucasians (p < 0.001). ULT with febuxostat 80 mg was superior to both febuxostat 40 mg (p < 0.001) and allopurinol (p = 0.004). Febuxostat 40 mg was comparable in efficacy to allopurinol. Significantly more African American subjects with mild or moderate renal impairment achieved sUA < 6.0 mg/dL in the febuxostat 80 group than in either the febuxostat 40 mg or allopurinol group (p < 0.05). Efficacy rates in all treatment groups regardless of renal function were comparable between African American and Caucasian subjects, as were AE rates.
In African American subjects with significant comorbidities, febuxostat 80 mg is significantly more efficacious than either febuxostat 40 mg or allopurinol 200/300 mg. Febuxostat was well tolerated in this African American population.
Please see related article: http://www.biomedcentral.com/1741-7015/10/15
The incidence of gout rises with increasing age. Management of elderly (≥65 years) gout patients can be challenging due to high rates of comorbidities, such as renal impairment and cardiovascular disease, and concomitant medication use. However, there is little data specifically addressing the efficacy and safety of available urate-lowering therapies (ULT) in the elderly. The objective of this post hoc analysis was to examine the efficacy and safety of ULT with febuxostat or allopurinol in a subset of elderly subjects enrolled in the CONFIRMS trial.
Hyperuricemic (serum urate [sUA] levels ≥ 8.0 mg/dL) gout subjects were enrolled in the 6-month, double-blind, randomized, comparative CONFIRMS trial and randomized, 1:1:1, to receive febuxostat, 40 mg or 80 mg, or allopurinol (200 mg or 300 mg based on renal function) once daily. Flare prophylaxis was provided throughout the study duration.
Study endpoints were the percent of elderly subjects with sUA <6.0 mg/dL at the final visit, overall and by renal function status, percent change in sUA from baseline to final visit, flare rates, and rates of adverse events (AEs).
Of 2,269 subjects enrolled, 374 were elderly. Febuxostat 80 mg was significantly more efficacious (82.0%) than febuxostat 40 mg (61.7%; p < 0.001) or allopurinol (47.3%; p < 0.001) for achieving the primary efficacy endpoint. Febuxostat 40 mg was also superior to allopurinol in this population (p = 0.029). In subjects with mild-to-moderate renal impairment, significantly greater ULT efficacy was observed with febuxostat 40 mg (61.6%; p = 0.028) and febuxostat 80 mg (82.5%; p < 0.001) compared to allopurinol 200/300 mg (46.9%). Compared to allopurinol 200/300 mg, the mean percent change in sUA from baseline was significantly greater for both febuxostat 80 mg (p < 0.001) and febuxostat 40 mg (p = 0.011) groups. Flare rates declined steadily in all treatment groups. Rates of AEs were low and comparable across treatments.
These data suggest that either dose of febuxostat is superior to commonly prescribed fixed doses of allopurinol (200/300 mg) in subjects ≥65 years of age with high rates of renal dysfunction. In addition, in this high-risk population, ULT with either drug was well tolerated.
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.
To review the clinical evidence (phase II and III studies) of the effectiveness and safety of febuxostat for treatment of hyperuricemia and gout.
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.
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.
febuxostat; gout; hyperuricemia; evidence
This is a case report of a patient with treatment resistant gout who was prescribed pegloticase and developed a severe reaction. A 30-year-old Hawaiian-Filipino man presented with a nine-year history of gout that progressed from episodic monoarticular arthritis, treated with aspiration and corticosteroid injections, to more aggressive disease with more frequent attacks requiring escalation of therapy. He was treated with systemic corticosteroids, colchicine and nonsteroidal anti-inflammatory drugs, but then required allopurinol. Despite aggressive therapy, the patient continued to have hyperuricemia and tophi developed even after treatment with febuxostat and probenicid. The patient became wheel chair bound due to his pain and, at that point, the decision was made to initiate treatment with pegloticase. The patient initially experienced significant improvement with treatment; however, he soon began to have elevation in his serum uric acid levels and developed a severe reaction during treatment.
pegloticase; tophi; treatment resistant gout; infusion reaction
Six generations of a Japanese family had gouty arthritis and progressive nephropathy. Data on nine of 51 women (18%) and 15 of 66 men (23%) with either asymptomatic hyperuricaemia, gouty arthritis, or renal insufficiency were obtained. Renal function in four men and one woman with hyperuricaemia or gouty arthritis was also examined. Urinary excretion of uric acid was decreased in all subjects examined, including the young. Erythrocyte phosphoribosylpyrophosphate synthetase and hypoxanthine-guanine phosphoribosyltransferase activities determined in 10 patients were normal. Some patients had been treated with allopurinol to reduce serum uric acid concentrations, but the treatment did not prevent progression of renal impairment. Transmission of the disease in this large family is considered to be autosomal dominant. The data suggest that the disease in this family is the same entity as that described by other workers--that is, familial urate nephropathy. As far as is known this is the largest family with this disease so far reported.
OBJECTIVES—To study the efficacy of allopurinol and benzbromarone to reduce serum urate concentrations in patients with primary chronic gout.
METHODS—Prospective, parallel, open study of 86 consecutive male patients with primary chronic gout. Forty nine patients (26 normal excretors and 23 under excretors) were given allopurinol 300 mg/day and 37 under excretors benzbromarone 100 mg/day. After achieving steady plasma urate concentrations with such doses, treatment was then adjusted to obtain optimal plasmatic urate concentrations (under 6 mg/dl).
RESULTS—Patients receiving allopurinol 300 mg/day showed a mean reduction of plasmatic urate of 2.75 mg/dl (from 8.60 to 5.85 mg/dl) and 3.34 mg/dl (from 9.10 to 5.76 mg/dl) in normal excretors and under excretors respectively. Patients receiving benzbromarone 100 mg/day achieved a reduction of plasmatic urate of 5.04 mg/dl (from 8.58 to 3.54 mg/dl). Fifty three per cent of patients receiving allopurinol and 100% receiving benzbromarone achieved optimal plasma urate concentrations at such doses. The patients with poor results with allopurinol 300 mg/day achieved a proper plasma urate concentration with allopurinol 450 to 600 mg/day, the mean final dose being 372 mg/day. Renal fuction improved and no case of renal lithiasis was observed among benzbromarone treated patients, whose mean final dose was 76 mg/day.
CONCLUSION—Benzbromarone is very effective to control plasma urate concentrations at doses ranging from 50 to 100 mg/day. Uricosuric treatment is a suitable approach to the treatment of patients with gout who show underexcretion of urate.
Keywords: gout; gout suppressants; allopurinol; benzbromarone
To assess the efficacy of fenofibrate treatment in combination with urate lowering agents in patients with gout.
Fourteen male patients with chronic tophaceous or recurrent acute attacks of gout were evaluated in an open-label pilot study of the hypolipidemic agent, fenofibrate (Lipidil Supra® 160 mg/d). Patients were stable on urate lowering agents (allopurinol or benzbromarone) for ≥three months without acute attack for the most recent one month before participating. All patients were being treated with established doses of urate lowering agents without modification throughout the study. Clinical and biochemical assessments including serum uric acid, creatinine, liver function test and fasting serum lipid were measured at (1) baseline (2) after two months of fenofibrate treatment and (3) two months after fenofibrate was withdrawn.
Serum uric acid was lowered by 23% after two months of fenofibrate treatment (6.93±2.16 vs. 5.22±1.16 mg/dL; p=0.016). Triglyceride levels were also reduced after fenofibrate treatment (p=0.001). However, this effect was reversed after the withdrawal (p=0.002) of the drug. Alkaline phosphatase was reduced after fenofibrate treatment (p=0.006), but increased 21% after the withdrawal of the drug (p=0.002). By contrast, serum levels of high density lipoprotein and creatinine were increased 9% (p=0.018) and 12% (p=0.006), respectively; however, both levels were significantly decreased to the baseline levels upon withdrawal of fenofibrate.
Fenofibrate can effectively reduce uric acid levels in addition to its known hypolipidemic effect. Fenofibrate may be used as a potential urate lowering agent in patients with gout, especially in those with coexisting hyperlipidemia.
Fenofibrate; Gout; Hyperuricemia; Hyperlipidemia
There is a disproportionate burden of gout in African-Americans in the U.S. due to a higher disease prevalence and lower likelihood of receiving urate-lowering therapy (ULT), compared to Caucasians. There is an absence of strong data as to whether the response to ULT differs by race/ethnicity. BMC Musculoskeletal Disorders recently published a secondary analyses of the CONFIRMS trial, a large randomized controlled, double-blind trial of 2,269 gout patients. The authors reported that the likelihood of achieving the primary study efficacy end-point of achieving serum urate < 6 mg/dl was similar between African-Americans and Caucasians, for all three treatment arms (Febuxostat 40 mg and 80 mg and allopurinol 300/200 mg). More importantly, rates were similar in subgroups of patients with mild or moderate renal insufficiency. Adverse event rates were similar, as were the rates of gout flares. These findings constitute a convincing evidence to pursue aggressive ULT in gout patients, regardless of race/ethnicity. This approach will likely help to narrow the documented racial disparities in gout care.
Please see related article: http://www.biomedcentral.com/1471-2474/13/15
Gout; Disparity; Race; treatment; Febuxostat; Allopurinol; randomized; African-American
Hyperuricemia, an integral component of metabolic syndrome, is a major health problem causing gout and renal damage. Urine alkalizers like citrate preparations facilitate renal excretion of the uric acid, but its supportive effect on xanthine oxidase inhibitors has not been tested as yet. We thus performed a randomized, prospective study, employing patients with elevated serum uric acid levels (≥7.0 mg/dL), or those treated for hyperuricemia. They were randomly enrolled into two study groups: the allopurinol monotherapy (MT) group or combination treatment (CT) group with allopurinol and a citrate preparation. Allopurinol (100 to 200 mg/day) in the absence or presence of a citrate preparation (3 g/day) was administered for 12 weeks and levels of serum uric acid, its urinary clearance (Cua), and the renal glomerular filtration rates assessed with the creatinine clearance (Ccr) were evaluated before and after the treatment. Serum levels of uric acid decreased significantly in both groups, while the change observed was much greater in CT group. Cua was significantly increased in CT group but not in MT group. Ccr was not altered in both groups in general, whereas it was significantly increased in a fraction of CT group with decreased renal function. These results indicate that an additional use of citrate preparations with xanthine oxidase inhibitors is beneficial for patients with hyperuricemia, reducing circulating uric acid and improving their glomerular filtration rates.
allopurinol; citrate preparation; creatinine clearance (Ccr); hyperuricemia; renal function
Gout is a disorder of purine metabolism, of varied etiology, associated with an increase in serum uric acid and a recurrent arthritis. The defect may be either metabolic or renal, or either unknown etiology or associated with other disease states. The acute arthritis has been shown to be due to a crystal (sodium urate) synovitis. The many chronic complications, arthritic, renal and vascular, necessitate a vigorous and longterm treatment program. With the advent of the xanthine oxidase inhibiter Allopurinol, excellent control of gout and its complications can be achieved in a large number of patients, with good control in the remainder.
Gout is a metabolic disorder characterized by elevated uric acid levels in the body, associated with painful arthritis, tophi and nephropathy. The most frequently used pharmacologic urate lowering strategies involve reducing urate production with a xanthine oxidase inhibitor and enhancing urinary excretion of uric acid with a uricosuric agent. Urate lowering agents are limited in number, availability and effectiveness. The emergence of a new medication, febuxostat, to lower serum urate levels is welcome as no new drug have been approved since the introduction of allopurinol, in 1964, and the drugs that are available have limitations owing to inefficacy or toxicity. Febuxostat is a novel, nonpurine selective inhibitor of xanthine oxidase, is a potential alternative to allopurinol for patients with hyperuricemia and gout.
Gout; hyperuricemia; xanthine oxidase inhibitor
The Western world appears to be in the midst of the third great gout epidemic of all time. In this century, gout is increasing in prevalence despite an increased understanding of its risk factors and pathophysiology, and the availability of reasonably effective treatment. The main cultural factors responsible for this appear to be diet, obesity, ethanol use and medications. Excess fructose consumption is a newly recognized modifiable risk factor. The debate has been renewed concerning hyperuricemia as an independent risk factor for renal insufficiency and cardiovascular disease. Prevention is still rooted in lifestyle choices. Existing treatments have proven to be unsatisfactory in many patients with comorbidities. New treatments are available today and on the horizon for tomorrow, which offer a better quality of life for gout sufferers. These include febuxostat, a nonpurine inhibitor of xanthine oxidase with a potentially better combination of efficacy and safety than allopurinol, and investigational inhibitors of URAT-1, an anion exchanger in the proximal tubule that is critical for uric acid homeostasis. New abortive treatments include interleukin-1 antagonists that can cut short the acute attack in 1 to 2 days in persons who cannot take nonsteroidal anti-inflammatory drugs, colchicine or corticosteroids. Lastly, newer formulations of uricase have the ability to dissolve destructive tophi over weeks or months in patients who cannot use currently available hypouricemic agents. Diagnostically, ultrasound and magnetic resonance imaging offer advanced ways to diagnose gout noninvasively, and just as importantly, a way to follow the progress of tophus dissolution. The close association of hyperuricemia with metabolic syndrome, hypertension and renal insufficiency ensures that nephrologists will see increasing numbers of gout-afflicted patients.
hyperuricemia; metabolic syndrome; tophi; colchicine; febuxostat; allopurinol
This study compared the effects of azapropazone and indomethacin plus allopurinol in the management of acute gout and hyperuricaemia. A group of 93 patients predominantly based in general practice were randomly allocated to the two treatment regimens (azapropazone (days 1-225) or indomethacin (1-28) followed by allopurinol (29-225)) on a double-blind double dummy basis. Azapropazone produced a substantial reduction in serum uric acid levels by day 4 compared with day 1 (P<0.002) and was superior to indomethacin with regard to recorded levels of serum uric acid at day 4 (P<0.01) and day 28 (P<0.05). From day 28 onwards allopurinol produced and azapropazone maintained similar reductions in serum uric acid. Both treatments rapidly controlled the initial acute attacks of gout and both produced side effects similar in frequency and nature. Fewer breakthrough attacks of gout occurred in the azapropazone group (12) than the indomethacin/allopurinol group (21).
Although the results achieved in both treatment groups were similar it has been shown that azapropazone is effective monotherapy for controlling both acute attacks of gout and hyperuricaemia.
Using the Intralipid lipid tolerance test we could not demonstrate any direct effect of serum triglyceride on uric acid or any influence of hyperuricaemia on triglyceride removal. This result supports previous studies suggesting that hyperuricaemia and hypertriglyceridaemia are linked through the association of obesity and alcohol excess rather than a direct cause and effect mechanism. It was possible to demonstrate significant reductions of serum triglyceride in patients with gout by reducing either their alcohol intake or body weight. Reduction of serum uric acid by probenecid had no effect on serum triglyceride or cholesterol. Similarly, allopurinol had no significant effect on serum triglyceride, but a significant fall of serum cholesterol was observed.
Gout is a common disease caused by hyperuricemia, which shows elevated serum uric acid (SUA) levels. From a viewpoint of urate handling in humans, gout patients can be divided into those with renal overload (ROL) gout with intestinal urate underexcretion, and those with renal underexcretion (RUE) gout. Recent genome-wide association studies (GWAS) revealed an association between SUA and a variant in human monocarboxylate transporter 9 (MCT9/SLC16A9) gene. Although the function of MCT9 remains unclear, urate is mostly excreted via intestine and kidney where MCT9 expression is observed. In this study, we investigated the relationship between a variant of MCT9 and gout in 545 patients and 1,115 healthy volunteers. A missense variant of MCT9 (K258T), rs2242206, significantly increased the risk of ROL gout (p = 0.012), with odds ratio (OR) of 1.28, although it revealed no significant association with all gout cases (p = 0.10), non-ROL gout cases (p = 0.83), and RUE gout cases (p = 0.34). In any case groups and the control group, minor allele frequencies of rs2242206 were >0.40. Therefore, rs2242206 is a common missense variant and is revealed to have an association with ROL gout, indicating that rs2242206 relates to decreased intestinal urate excretion rather than decreased renal urate excretion. Our study provides clues to better understand the pathophysiology of gout as well as the physiological roles of MCT9.
Gouty arthritis; Single nucleotide polymorphism (SNP); Gut urate excretion; Carnitine; Solute carrier (SLC) family transporter
To examine evidence-based quality indicators (QIs) in US veterans with gout diagnosis, and to examine the effect of demographics, heath care utilization/access, comorbid conditions, or physican characteristics as predictors of quality of gout care.
Using the Minneapolis Veterans Affairs electronic medical record system, we identified a cohort of veterans receiving medication to treat gout between January 1, 1999 and December 31, 2003, and evaluated 3 recently published evidence-based QIs for gout management: QI 1 = allopurinol dose <300 mg in gout patients with renal insufficiency, QI 2 = uric acid check within 6 months of starting a new allopurinol prescription, and QI 3 = complete blood count and creatine kinase check every 6 months for gout patients receiving prolonged colchicine therapy. We calculated the proportion of patients whose therapy adhered to each QI and to all applicable indicators (overall physician adherence). Logistic regression analysis examined association of overall physician adherence with sociodemographics, health care utilization, comorbidity, and provider characteristics.
Of 3,658 patients with a diagnosis of gout, 663 patients qualified for examination of ≥1 QI. Of these 663 patients, therapy in only 144 (22%) adhered to all applicable QIs; 59 (78%) of 76 adhered to QI 1, 155 (24%) of 643 adhered to QI 2, and 18 (35%) of 52 adhered to QI 3. Overall physician adherence to QIs was significantly lower in older veterans and in those with more inpatient visits per year, but was higher in those with more primary care visits or more health care providers.
Suboptimal physician adherence to QIs was seen for all 3 QIs tested in this cohort of veterans with gout. These findings can guide quality improvement efforts.
Gout; Veterans; Quality of care; Quality indicators; Physician adherence
Fifteen patients with clinical gout occurring after long term treatment with diuretics were studied retrospectively. In all 15 patients one or more additional factors were present which might have contributed to the hyperuricaemia and gout. The most common of these was the impairment of the glomerular filtration rate. Twenty five other patients receiving long term treatment with diuretics who did not have gout were also studied. The concentrations of uric acid, urea, and creatinine were, in general, markedly lower in these patients than in those who had developed gout. It is concluded that diuretic induced gout occurs in patients in whom there is an additional cause of hyperuricaemia, usually impaired renal function.
These experiments were designed to define the renal disposition of pyrazinoic acid in a nonhuman primate that is phylogenetically close to man and to relate this to the effects of pyrazinoate on urate excretion. The renal clearance of pyrazinoate was almost always greater than the simultaneous glomerular filtration rate at plasma concentrations ranging from 1.9 to 960 μg/ml. Some inhibitors of tubular secretion, probenecid, MK-282 (an experimental, potent uricosuric drug), p-aminohippurate, iodopyracet, sulfinpyrazone, and mersalyl, reduced clearances of pyrazinoate to values far below filtration rate. Chlorothiazide, allopurinol, and salicylate did not. The clearance of pyrazinoate was not influenced by changes in urine flow. It is concluded that pyrazinoate is actively secreted and actively reabsorbed.
Pyrazinoate had a dual effect on urate excretion. At concentrations in plasma less than 10 μg/ml there was a concentration related fall in urate/inulin clearance ratio, reaching values of 10-20% of control. Over the range of 10-100 μg/ml in plasma, the clearance of urate remained maximally depressed. At higher concentrations of pyrazinoate there was a concentration related increase in urate/inulin clearance ratio such that at pyrazinoate levels above 600 μg/ml a definite uricosuric response was obtained. Prior administration of pyrazinoate to give plasma levels of 20-140 μg/ml completely or almost completely prevented uricosuric responses to probenecid, PAH, chlorothiazide, and sulfinpyrazone. Iodopyracet, mersalyl, salicylate and N-acetyl-4-dibutylsulfamoyl-3-trifluoromethylbenzenesulfonamide (MK-282) retained significant uricosuric action, but the activities were probably less than normal. The results are consistent with a model of urate transport involving high rates of bidirectional transtubular flux.
The past decade has witnessed an exponential increase of novel therapeutic modalities for a variety of rheumatic disorders, including gout. During the past few years two novel therapeutic agents have been approved by the US Food and Drug Administration for the treatment of hyperuricemia in patients with gout, one of them being febuxostat, a nonpurine selective inhibitor of xanthine oxidase. Review of its pharmacokinetics and pharmacodynamics, efficacy and safety profile, and use in gout patients with comorbid conditions reveals that age and gender have no clinically significant effect and dose adjustments based on age or gender are not required. In addition, febuxostat can be used in patients with mild-to-moderate renal or hepatic involvement. Its overall efficacy and safety profile is comparable and, in certain subsets such as gout patients with mild and moderate renal insufficiency, is superior to allopurinol.
hyperuricemia; febuxostat; gout; safety profile; efficacy profile
To determine whether hypouricaemic treatment results in the disappearance of urate crystals from gouty joints and to define the time required.
In 18 patients with monosodium urate (MSU) crystal proven gout, and after the initiation of successful serum uric acid (SUA)‐lowering treatment, an arthrocentesis of the asymptomatic signal joint (11 knees, 7 first metatarsophalangeal joints) was performed every 3 months to obtain a synovial fluid (SF) sample. The sample was then analysed for the presence of MSU crystals, and the number of crystals/400× field was noted. SUA levels and the duration of gout were also noted.
MSU crystals disappeared from the SF of all 18 joints after reduction of SUA to normal levels. The time required for disappearance ranged from 3 to 33 months; disappearance time correlated with the duration of gout (rs = 0.71; p<0.01). The median number of MSU crystals in the SF samples before urate‐lowering treatment was 7.5 (2.5–11) crystals/400× field, reducing to 3 (1–6.5) crystals/400× field (p<0.05) at 3 months. Crystal counts continued to decrease after 3 months.
In gout, reduction of SUA to normal levels results in disappearance of urate crystals from SF, requiring a longer time in those patients with gout of longer duration. This indicates that urate crystal deposition in joints is reversible. Normalisation of SUA levels results in a decrease in the concentration of MSU crystals in SF in the asymptomatic gouty joints. This may partially explain the reduced frequency of gouty attacks when a patient has been treated with SUA‐lowering drugs.
gout; monosodium urate crystals; synovial fluid; gout treatment