UMLS:C0018099 - FACTA Search

Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0018099 (gout)
5,192 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanism of allopurinol [4-hydroxypyrazolo(3,4-d)pyrimidine] transport into human erythrocytes was investigated with an inhibitor stop assay. Allopurinol transport could be resolved into two components: (1) a saturable system and (2) a non-saturable process, which most likely represents non-facilitated diffusion. Allopurinol transport had a Km of 268 mumol/L and a Vmax of 28 pmol/microL intracellular volume/sec; the non-saturable component was 0.0195/sec. Mutual inhibition studies showed that the competitive Ki values of hypoxanthine and adenine on allopurinol transport were 120 and 3 mumol/L, respectively. These Ki values as well as the IC50 values of 100-150 mumol/L for hypoxanthine and 3-10 mumol/L for adenine were similar to the corresponding transport Km values of these bases, which are 128 and 8 mumol/L, respectively. The Ki of allopurinol on hypoxanthine transport was 274 mumol/L and thus nearly identical to its Km. Thus in erythrocytes the uricostatic agent allopurinol is an alternative substrate for the purine transport system, but lacks the exceptional high affinity it has for xanthine oxidase. This could explain the paradoxical clinical side effect of allopurinol, namely that it can provoke an attack of gout. Theophylline, a methylated purine, inhibited allopurinol transport with an IC50 of 200-400 mumol/L. Oxypurinol [4,6-dihydroxypyrazolo(3,4-d)pyrimidine], the main metabolite of allopurinol, also inhibited allopurinol transport with an IC50 of 20-40 mumol/L. This is noteworthy, since allopurinol and oxypurinol do not share the same transport system in the kidney.
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PMID:Allopurinol transport in human erythrocytes. 845 64

Allopurinol is used frequently to treat patients with gout and hyperuricemia. However, adverse effects associated with this agent have been reported occasionally, especially among patients with hyperuricemia complicated with renal diseases. A rise in the blood concentration of oxipurinol, the chief active metabolite of allopurinol, has been noted in patients with renal dysfunctions, pointing to an implication of oxipurinol toxicity. It has been reported that monitoring the serum oxipurinol concentration to maintain in level below 15.2 micrograms/ml (= 100 mumol/l: recommended level) is helpful in avoiding toxicity. At Jikei University Hospital, a survey was conducted on 148 hyperuricemic patients who had been treated with allopurinol at the dosages of 50, 100, 200 and 300 mg daily or 100 mg on alternate days for more than one month. Because oxipurinol is an uricosuric substance, the steady-state serum oxipurinol concentration was determined by HPLC; and creatinine clearance (CCr) was calculated for each patient. 1. In the group composed of patients with normal kidney function (CCr > or = 80 ml/min), increase in the dosage of allopurinol was associated with a linear increase in the serum concentration of oxipurinol. 2. Among the patients with varying renal function who were receiving 100 mg of allopurinol daily, the oxipurinol level increased logarithmically as the creatinine clearance decreased. In some of the patients with renal insufficiency (CCr < 30 ml/min), daily administration of 100 mg of allopurinol resulted in a serum concentration of oxipurinol over 15.2 micrograms/ml. 3. For patients with renal insufficiency (CCr < 30 ml/min), administration of allopurinol at the dosage of 50 mg/day is considered adequate to avoid the accumulation of serum oxipurinol.
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PMID:[A study of serum oxipurinol concentration and renal function in patients administered allopurinol]. 901 85

To investigate whether allopurinol and benzbromarone affect the concentration of uridine in plasma, allopurinol or benzbromarone were administered to patients with gout for 3 to 6 months. Allopurinol decreased the concentrations of uridine and uric acid in plasma and the urinary excretion of uric acid, but increased the plasma concentration and urinary excretion of oxypurines and orotidine. Benzbromarone decreased the concentration of uric acid in plasma and increased the excretion of uric acid in urine. However, it did not affect the plasma concentration of uridine or oxypurines or the urinary excretion of oxypurines or orotidine. These results suggest that orotidilytic decarboxylase was inhibited by allopurinol and oxypurinol ribonucleotides and/or that phosphoribosyl pyrophosphate (PRPP) was consumed by conversion from hypoxanthine, allopurinol, and oxypurinol to the respective ribonucleotides, resulting in a decrease in the de novo synthesis of pyrimidine leading to the decreased concentration of uridine in plasma. Furthermore, it was suggested that benzbromarone did not affect the de novo synthesis of pyrimidine or purine.
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PMID:Effect of allopurinol and benzbromarone on the concentration of uridine in plasma. 943 46

Gout in the elderly differs from classical gout found in middle-aged men in several respects: it has a more equal gender distribution, frequent polyarticular presentation with involvement of the joints of the upper extremities, fewer acute gouty episodes, a more indolent chronic clinical course, and an increased incidence of tophi. Long term diuretic use in patients with hypertension or congestive cardiac failure, renal insufficiency, prophylactic low dose aspirin (acetylsalicylic acid), and alcohol (ethanol) abuse (particularly by men) are factors associated with the development of hyperuricaemia and gout in the elderly. Extreme caution is necessary when prescribing nonsteroidal anti-inflammatory drugs (NSAIDs) for the treatment of acute gouty arthritis in the elderly. NSAIDs with short plasma half-life (such as diclofenac and ketoprofen) are preferred, but these drugs are not recommended in patients with peptic ulcer disease, renal failure, uncontrolled hypertension or cardiac failure. Colchicine is poorly tolerated in the elderly and is best avoided. Intra-articular and systemic corticosteroids are increasingly being used for treating acute gouty flares in aged patients with medical disorders contraindicating NSAID therapy. Urate-lowering drugs are indicated for the treatment of hyperuricaemia and chronic gouty arthritis. Uricosuric drugs are poorly tolerated and the frequent presence of renal impairment in the elderly renders these drugs ineffective. Allopurinol is the urate-lowering drug of choice, but its use in the aged is associated with an increased incidence of both cutaneous and severe hypersensitivity reactions. To minimise this risk, allopurinol dose must be kept low. A starting dose of allopurinal 50 to 100mg on alternate days, to a maximum daily dose of about 100 to 300mg, based upon the patient's creatinine clearance and serum urate level, is recommended. Asymptomatic hyperuricaemia is not an indication for long term urate-lowering therapy; the risks of drug toxicity often outweigh any benefit.
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PMID:Gout in the elderly. Clinical presentation and treatment. 978 27

A major obstacle to the treatment of hyperuricemia in patients allergic to allopurinol is the limited availability of suitable, equally effective, alternative, urate-lowering drugs. Conventional uricosuric drugs, including probenecid and sulfinpyrazone, are recommended for allopurinol- intolerant patients with gout and "underexcretion" hyperuricemia who have normal renal function and no history of nephrolithiasis. Therapeutic options in those in whom traditional uricosuric drugs are contraindicated, ineffective, or poorly tolerated include slow oral desensitization to allopurinol and cautious administration of oxipurinol. Allopurinol desensitization is useful particularly in those who have failed other treatment modalities. If available (as in Europe, South Africa, and Japan), benzbromarone may be tried in patients with gout and mild-to-moderate renal insufficiency. Recombinant urate oxidase can be used in the short-term prophylaxis and treatment of chemotherapy- associated hyperuricemia in patients with lymphoproliferative and myeloproliferative disorders. Hyperuricemia and gout occur with increased frequency in cyclosporine-treated allograft transplant recipients. The management of gout in these patients is complicated by two main factors: cyclosporine-induced renal impairment, and interactions with medications used to preserve the allograft.
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PMID:Difficult gout and new approaches for control of hyperuricemia in the allopurinol-allergic patient. 1117 68

Xanthine oxidase (XO) is a highly versatile flavoprotein enzyme, ubiquitous among species (from bacteria to human) and within the various tissues of mammals. The enzyme catalyses the oxidative hydroxylation of purine substrates at the molybdenum centre (the reductive half-reaction) and subsequent reduction of O(2) at the flavin centre with generation of reactive oxygen species (ROS), either superoxide anion radical or hydrogen peroxide (the oxidative half-reaction). Many diseases, or at least symptoms of diseases, arise from a deficiency or excess of a specific metabolite in the body. For an example of an excess of a particular metabolite that produces a disease state is the excess of uric acid which can led to gout. Inhibition of XO decreases the uric acid levels, and results in an antihyperuricemic effect. Allopurinol, first synthesised as a potential anticancer agent, is nowadays a clinically useful xanthine oxidase inhibitor used in the treatment of gout. There is overwhelming acceptance that xanthine oxidase serum levels are significantly increased in various pathological states like hepatitis, inflammation, ischemia-reperfusion, carcinogenesis and aging and that ROS generated in the enzymatic process are involved in oxidative damage. Thus, it may be possible that the inhibition of this enzymatic pathway would be beneficial. In this review the State of the Art will be presented, which includes a summary of the progress made over the past years in the knowledge of the structure and mechanism of the enzyme, associated pathological states, and in the efforts made towards the development of new xanthine oxidase inhibitors.
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PMID:Progress towards the discovery of xanthine oxidase inhibitors. 1186 Mar 55

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.
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PMID:Gout and hyperuricemia. 1198 27

Pustular drug eruptions are uncommon and usually present with an acute illness. A 75-year-old-woman presented with a widespread pruritic pustular erythematous skin rash. She was otherwise well and had been commenced on allopurinol for gout 3 weeks before developing the rash. A skin biopsy was consistent with a pustular drug eruption, with features of acute generalized exanthematous pustulosis (AGEP). Allopurinol was the probable causative agent and withdrawal resulted in resolution of her eruption within 6 weeks. A diagnosis of AGEP was considered; however, this patient did not fulfil the diagnostic criteria.
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PMID:Allopurinol-induced pustular eruption: an unusually mild case. 1198 73

Oxipurinol [alloxanthine, Oxyprim, oxypurinol] is the active metabolite of the only commercially available xanthine oxidase inhibitor, allopurinol. Oxipurinol is also a xanthine oxidase inhibitor. Oxipurinol is currently being developed by Cardiome Pharma. It is waiting for approval in the US for the treatment of allopurinol-intolerant hyperuricaemia (gout) and is in phase III trials for the treatment of congestive heart failure. Allopurinol is indicated for the treatment of symptomatic hyperuricaemia, or gout. Approximately 3-5% of patients receiving allopurinol develop intolerance to the drug. Oxipurinol was originally developed by Burroughs Wellcome (later GlaxoSmithKline), and has been available on a compassionate-use basis since 1967 for use in allopurinol-intolerant patients. The licensee company ILEX Oncology has stated that oxipurinol does not have patent protection. Oxipurinol's potential for treatment of congestive heart failure is based on the possibility that xanthine oxidase inhibitors may improve myocardial work efficiency by sensitising cardiac muscle cells to calcium ions, which are a key determinant of cardiac muscle function. This results in more efficient contraction of cardiac muscle cells, without the same increase in oxygen demand. At the second annual BioPartnering North America conference (BPN-2004) [February 2004, Vancouver, Canada], Cardiome Pharma stated that it was seeking a commercialisation partner to market and distribute oxipurinol in the US for the treatment of allopurinol-intolerant hyperuricaemia. In 1995, ILEX Oncology obtained an exclusive licence to oxipurinol from Burroughs Wellcome. Burroughs Wellcome later became part of Glaxo Wellcome, which merged with SmithKline Beecham in December 2000 to form GlaxoSmithKline. ILEX's licence agreement is now with GlaxoSmithKline and The Wellcome Foundation. In December 2001, ILEX granted Paralex, a privately held New York-based company, an exclusive sublicence to all of ILEX's rights to oxipurinol for the treatment of hyperuricaemia in allopurinol-intolerant patients. Paralex additionally gained the right to develop and commercialise oxipurinol in all fields, under data and technology owned by ILEX. Furthermore, Paralex had licensed certain intellectual property rights from The John Hopkins University relating to cardiovascular applications of xanthine oxidase inhibitors. Paralex was acquired by Cardiome Pharma in March 2002. Cardiome Pharma announced early in May 2002 that it had exercised its option to acquire from ILEX Oncology Inc. rights to clinical trial data for oxypurinol for the treatment of gout in allopurinol-intolerant patients. ILEX completed its open-label phase II clinical study of Oxyprim in allopurinol-intolerant gout patients, and the trial data were transferred to Cardiome. Cardiome stated in May 2002 that it intended to commence a further phase II trial of oxypurinol in gout. Phase III trials were in progress in 2003 in this indication. In 1995, ILEX Oncology continued the compassionate use distribution of oxipurinol while establishing a US FDA-approved registration plan for the agent. In November 1998, ILEX received Orphan Drug status for the use of oxipurinol in patients with symptomatic hyperuricaemia. ILEX Oncology's Development Pipeline for 1998 stated that oxipurinol had entered phase II clinical trials for the treatment of hyperuricaemia. In 2001, the clinical trials listing service CenterWatch stated that oxipurinol was in a phase II clinical trial with ILEX Oncology for the treatment of symptomatic hyperuricaemia in patients who are intolerant to allopurinol. The trial appeared to be taking place in the US, and was a multicentre, open-label, 14-week study in 90 patients. In February 2003, Cardiome confirmed beginning patient enrollment in three smaller phase II studies, with the first trial (EXOTIC) now completed. These three smaller proof-of-concept studies will observe surrogate endpoints such as cardiac output and exercise tolerance. The second proof-of-concept study in patients with CHF of ischemic aetiology (IV), known as EXOTIC-EF (Evaluation of XanThine Oxidase Inhibition on Cardiac Ejection Fraction), will assess the effects of oxypurinol on left ventricular performance. The EXOTIC-EF trial will start in the first quarter of 2004 and be completed by the second quarter of 2004. The third, LA PLATA, proof-of-concept study will explore the effects of 1 month of oral oxypurinol therapy on exercise capacity and left ventricular performance. It is projected that the LA PLATA study will start in the first quarter of 2004 and be completed by the third quarter of 2004. During the Heart Failure Society of America's meeting on 21 September 2003, Cardiome presented clinical data from its first proof-of-concept EXOTIC (European Xanthine Oxidase Inhibitors Trial In Cardiac Disease) study. Cardiome intends to conduct a second trial, at the Eppendorf Clinic at the University of Hamburg, to determine the effect of oxypurinol on left ventricular performance in patients with CHF of ischaemic aetiology. This study will be an extension of the original proof-of-concept study. According to the 1st Annual BioPartnering conference held in Vancouver, Canada, in February 2003, Cardiome is seeking co-development partners for oxipurinol in the treatment of congestive heart failure. In July 2003, the US Patent and Trademark Office issued a new patent providing additional protection to Cardiome's programme focused on treatment of congestive heart failure with oxypurinol. The patent, No. 6,569,862, was the second issued to the Johns Hopkins University (JHU) in this field. The key claims in the new patent cover use of the entire family of drugs known as xanthine oxidase inhibitors applied to contractile disorders of the heart, including congestive heart failure. An earlier patent issued to JHU contained provisions relating to a specific mechanism of action and to specific forms of heart disease. Both patents and related intellectual property are licensed exclusively to Cardiome.
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PMID:Oxipurinol: alloxanthine, Oxyprim, oxypurinol. 1513 81

Uric acid stones occur in 10% of all kidney stones and are the second most-common cause of urinary stones after calcium oxalate and calcium phosphate calculi. The most important risk factor for uric acid crystallization and stone formation is a low urine pH (below 5.5) rather than an increased urinary uric acid excretion. Main causes of low urine pH are tubular disorders (including gout), chronic diarrhea or severe dehydration. Uric acid stone disease can be prevented and these are one of the few urinary tract stones that can be dissolved successfully. The treatment of uric acid stones consists not only of hydration (urine volume above 2000 ml daily), but mainly of urine alkalinization to pH values between 6.2 and 6.8. Urinary alkalization with potassium citrate or sodium bicarbonate is a highly effective treatment, resulting in dissolution of existing stones. Urinary uric acid excretion can be reduced by a low-purine diet. Potassium citrate is the treatment of choice for the prevention of recurrence of uric acid calculi. Allopurinol reduces the frequency of stone formation in hyperuricosuric patients with recurrent uric acid stones and/or gout.
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PMID:[Diagnosis and prevention of uric acid stones]. 1549 18

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