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Uric acid, Proton pump inhibitor, Immune defense, and Esophageal acidity

February 2017

Uric acid

Epidemiology of hyperuricemia and gout.

Gout is an increasingly common medical problem. The traditional risk factors of male sex and high red meat or alcohol consumption have been joined by a wave of newer risk factors, such as increased longevity, the metabolic syndrome (hypertension, diabetes, dyslipidemia, truncal obesity, increased cardiovascular disease risk), use of diuretics, low-dose aspirin, or cyclosporine, and end-stage renal disease. Atypical presentations of gout in the elderly can mimic osteoarthritis and rheumatoid arthritis. There is a resurgence of interest in hyperuricemia as an independent and potentially modifiable cardiovascular risk factor. The pharmacologic management of gout in general practice suffers from a number of quality-control issues. This article reviews these and other new epidemiologic data on this ancient disease.

Am J Manag Care. 2005 Nov;11(15 Suppl):S435-42; quiz S465-8

Increasing prevalence of gout and hyperuricemia over 10 years among older adults in a managed care population.

OBJECTIVE: To determine whether the prevalence of gout and/or clinically significant hyperuricemia increased in a managed care population over 10 years. METHODS: The study was a descriptive analysis utilizing an administrative claims database to ascertain 10-year trends in prevalence of gout and/or hyperuricemia. Prevalence rates were calculated cross-sectionally for each year (1990-99) and expressed/compared as rates per 1000 enrollees. RESULTS: The prevalence of gout and/or hyperuricemia in the overall population increased by about 2 cases per 1000 enrollees over 10 years. In the > 75 year age group, rates increased from 21 per 1000 persons in 1990 to 41 per 1000 in 1999. In the 65-74 year age group, prevalence increased from between 21 and 24 per 1000 persons in the years 1990-92 to over 31 per 1000 during the years 1997-99. Prevalence rates in younger age groups (< 65 years) stayed consistently low during the years under study. There were sex differences in most age groups, with men having the greater burden of disease at every time point. CONCLUSION: Prevalence of gout and/or hyperuricemia in the overall study population increased during the 10-year period. When stratified by age, there were increases in prevalence among groups over age 65 in both sexes. Although gout prevalence increased in both sexes over the 10-year period, men still had most of the burden of disease. In ages younger than 65, men had 4 times higher prevalence than women (4:1 ratio), but in the older age groups (> 65), the gender gap narrowed to 1 woman to every 3 men with gout and/or hyperuricemia (3:1 ratio).

J Rheumatol. 2004 Aug;31(8):1582-7

Increased risk of vascular disease associated with gout: a retrospective, matched cohort study in the UK clinical practice research datalink.

OBJECTIVES: To determine whether gout increases risk of incident coronary heart disease (CHD), cerebrovascular (CVD) and peripheral vascular disease (PVD) in a large cohort of primary care patients with gout, since there have been no such large studies in primary care. METHODS: A retrospective cohort study was performed using data from the Clinical Practice Research Datalink (CPRD). Risk of incident CHD, CVD and PVD was compared in 8386 patients with an incident diagnosis of gout, and 39 766 age, sex and registered general practice-matched controls, all aged over 50 years and with no prior vascular history, in the 10 years following incidence of gout, or matched index date (baseline). Multivariable Cox Regression was used to estimate HRs and covariates included sex and baseline measures of age, Body Mass Index, smoking, alcohol consumption, Charlson comorbidity index, history of hypertension, hyperlipidaemia, chronic kidney disease, statin use and aspirin use. RESULTS: Multivariable analysis showed men were at increased risk of any vascular event (HRs (95% CIs)) HR 1.06 (1.01 to 1.12), any CHD HR 1.08 (1.01 to 1.15) and PVD HR 1.18 (1.01 to 1.38), while women were at increased risk of any vascular event, HR 1.25 (1.15 to 1.35), any CHD HR 1.25 (1.12 to 1.39), and PVD 1.89 (1.50 to 2.38)) but not any CVD. CONCLUSIONS: In this cohort of over 50s with gout, female patients with gout were at greatest risk of incident vascular events, even after adjustment for vascular risk factors, despite a higher prevalence of both gout and vascular disease in men. Further research is required to establish the reason for this sex difference.

Ann Rheum Dis. 2015 Apr;74(4):642-7

Presence of gout is associated with increased prevalence and severity of knee osteoarthritis among older men: results of a pilot study.

BACKGROUND: Gout and osteoarthritis (OA) are the most prevalent arthritides, but their relationship is neither well established nor well understood. OBJECTIVES: We assessed whether a diagnosis of gout or asymptomatic hyperuricemia (AH) is associated with increased prevalence/severity of knee OA. METHODS: One hundred nineteen male patients aged 55 to 85 years were sequentially enrolled from the primary care clinics of an urban Veterans Affairs hospital, assessed and categorized into 3 groups: gout (American College of Rheumatology Classification Criteria), AH (serum urate ≥6.8 mg/dL, no gout), and control (serum urate <6.8 mg/dL, no gout). Twenty-five patients from each group subsequently underwent formal assessment of knee OA presence and severity (American College of Rheumatology Clinical/Radiographic Criteria, Kellgren-Lawrence grade). Musculoskeletal ultrasound was used to detect monosodium urate deposition at the knees and first metatarsophalangeal joints. RESULTS: The study showed 68.0% of gout, 52.0% of AH, and 28.0% of age-matched control subjects had knee OA (gout vs control, P = 0.017). Odds ratio for knee OA in gout versus control subjects was 5.46 prior to and 3.80 after adjusting for body mass index. Gout subjects also had higher Kellgren-Lawrence grades than did the control subjects (P = 0.001). Subjects with sonographically detected monosodium urate crystal deposition on cartilage were more likely to have OA than those without (60.0 vs 27.5%, P = 0.037), with crystal deposition at the first metatarsophalangeal joints correlating most closely with OA knee involvement. CONCLUSIONS: Knee OA was more prevalent in gout patients versus control subjects and intermediate in AH. Knee OA was more severe in gout patients versus control subjects.

J Clin Rheumatol. 2015 Mar;21(2):63-71

Gout: an update.

Arthritis caused by gout (i.e., gouty arthritis) accounts for millions of outpatient visits annually, and the prevalence is increasing. Gout is caused by monosodium urate crystal deposition in tissues leading to arthritis, soft tissue masses (i.e., tophi), nephrolithiasis, and urate nephropathy. The biologic precursor to gout is elevated serum uric acid levels (i.e., hyperuricemia). Asymptomatic hyperuricemia is common and usually does not progress to clinical gout. Acute gout most often presents as attacks of pain, erythema, and swelling of one or a few joints in the lower extremities. The diagnosis is confirmed if monosodium urate crystals are present in synovial fluid. First-line therapy for acute gout is nonsteroidal anti-inflammatory drugs or corticosteroids, depending on comorbidities; colchicine is second-line therapy. After the first gout attack, modifiable risk factors (e.g., high-purine diet, alcohol use, obesity, diuretic therapy) should be addressed. Urate-lowering therapy for gout is initiated after multiple attacks or after the development of tophi or urate nephrolithiasis. Allopurinol is the most common therapy for chronic gout. Uricosuric agents are alternative therapies in patients with preserved renal function and no history of nephrolithiasis. During urate-lowering therapy, the dose should be titrated upward until the serum uric acid level is less than 6 mg per dL (355 micromol per L). When initiating urate-lowering therapy, concurrent prophylactic therapy with low-dose colchicine for three to six months may reduce flare-ups.

Am Fam Physician. 2007 Sep 15;76(6):801-8

An open-label, 6-month study of allopurinol safety in gout: The LASSO study.

OBJECTIVES: Allopurinol is the most widely prescribed serum uric acid-lowering therapy (ULT) in gout. To achieve serum uric acid (sUA) concentrations associated with clinical benefit, allopurinol is serially uptitrated with sUA monitoring. Suboptimal dosing is a key contributor to poor clinical outcomes, but few data are available on the safety and efficacy of dose-titrated allopurinol, particularly at doses > 300 mg/d. The objective of this open-label study was to investigate the safety and efficacy of allopurinol under conditions where investigators were encouraged to titrate to optimal, medically appropriate doses. METHODS: Long-term Allopurinol Safety Study Evaluating Outcomes in Gout Patients (LASSO) was a large, 6-month, multicenter study of allopurinol (NCT01391325). Adults meeting American Rheumatism Association Criteria for Classification of Acute Arthritis of Primary Gout and ≥ 2 gout flares in the previous year were eligible. Investigators were encouraged (but not required) to titrate allopurinol doses to achieve target sUA < 6.0mg/dL. The primary objective was evaluation of the safety of dose-titrated allopurinol by clinical and laboratory examinations at monthly visits. Secondary objectives included sUA-lowering efficacy and gout flare frequency. RESULTS: Of 1735 patients enrolled, 1732 received ≥ 1 allopurinol doses. The maximal daily allopurinol dose during study was < 300 mg in 14.4%, 300 mg in 65.4%, and > 300 mg in 20.2% of patients; dosing duration was 115.5, 152.0, and 159.7 days, respectively. Overall, baseline demographic characteristics and comorbidity rates were similar across these three categories, but patients receiving > 300-mg maximal dose had more severe gout. Treatment-emergent adverse events possibly related to allopurinol occurred in 15.2%, 9.5%, and 11.4% of patients in the < 300-, 300-, and > 300-mg categories, respectively. Rash incidence was low (1.5%) and allopurinol hypersensitivity syndrome was not reported. No clinically meaningful changes occurred in laboratory values. sUA < 6.0mg/dL at month 6 was achieved by 35.9% of patients overall: 22.4%, 35.0%, and 48.3% in dosing categories < 300, 300, and > 300 mg, respectively. CONCLUSIONS: This large multicenter study found that the allopurinol dose-titration strategy was well tolerated, without new safety signals emerging over 6 months. However, despite encouragement to treat to target, significant proportions of patients did not achieve target sUA.

Semin Arthritis Rheum. 2015 Oct;45(2):174-83

Safety of a Novel Botanical Extract Formula for Ameliorating Allergic rhinitis. Part II.

Abstract Each year more than 50 million Americans suffer from allergic rhinitis, which is a state of hypersensitivity or hyperimmunity. Basically, allergic rhinitis is symptomatically recognized as the inflammation and irritation of the nasal mucosal membranes; sneezing; stuffy/runny nose; nasal congestion; and itchy; watery, and swollen eyes; and defined as a state of hypersensitivity/ hyperimmunity caused by exposure to a particular allergen (antigen) that results in increased reactivity upon subsequent exposure. A novel polyherbal formulation (Aller-7/NR-A2) was developed for the treatment of allergic rhinitis using a unique combination of extracts from seven medicinal plants, including Phyllanthus emblica, Terminalia chebula, Terminalia bellerica, Albizia lebbeck, Piper nigrum, Zingiber officinale, and Piper longum. Earlier studies in our laboratories have demonstrated potent antihistaminic, anti-inflammatory, antispasmodic, antioxidant, and mast-cell stabilization activities of Aller-7 in addition to its efficacy in a clinical setting. A series of preliminary toxicological evaluations were also conducted in the past, which demonstrated its safety. In this study, we have conducted further safety studies on Aller-7, including acute oral, acute dermal, acute dermal irritation, eye irritation, and 90-day repeated dose toxicity studies. Acute oral toxicity of Aller-7 was found to be greater than 5,000 mg/kg body weight in both male and female rats and no mortality or toxicity was observed at this dose, while the acute dermal toxicity was found to be greater than 2,000 mg/kg body weight. In the acute dermal irritation study, the skin irritancy index was found to be 0.0, which classifies Aller-7 as a nonirritant to rabbit skin. In the acute eye irritation study, Aller-7 was found to have minimal irritancy to eyes of rabbits. In the repeated-dose 90-day oral toxicity study, Aller-7 was administered at dose levels of 100, 300, and 1,000 mg/kg rat body weight for 90 consecutive days by oral gavage. Aller-7 did not induce any significant change in the hematological parameters. No ocular abnormalities were observed. Some minor histopathological changes were observed, but did not reveal any significant treatment-related histopathological changes. The above findings revealed that the no observed adverse effect level (NOAEL) of Aller-7 is greater than 1,000 mg/kg body weight. Taken together, these studies demonstrate the broad spectrum safety of Aller-7.

Toxicol Mech Methods. 2005;15(3):193-204

Safety of a novel botanical extract formula for ameliorating allergic rhinitis.

Allergic rhinitis (also known as hay fever) is the most commonly occurring immunological disorder, and it affects 40 million men, women, and children in the United States. Symptomatically, it is an inflammation and irritation of the mucous membranes that line the nose. Allergy is defined as a state of hypersensitivity or hyperimmunity caused by exposure to a particular antigen (allergen) that results in increased reactivity upon subsequent exposure. A novel botanical formulation, Aller-7/NR-A2, was developed for the treatment of allergic rhinitis; it is a combination of medicinal plant extracts from Phyllanthus emblica, Terminalia chebula, Terminalia bellerica, Albizia lebbeck, Piper nigrum, Zingiber officinale, and Piper longum. This novel formulation has demonstrated potent antihistaminic, anti-inflammatory, antispasmodic, antioxidant, and mast-cell-stabilization activities. All of the doses for these toxicity studies were selected according to the guidelines of the Organization for Economic Cooperation and Development, the World Health Organization, and the Environmental Protection Agency. Acute toxicity of Aller-7 was evaluated in Swiss Albino mice at doses of 125, 250, 500, 1000, and 1500 mg/kg. After 15 days of treatment, the animals were sacrificed. No histopathological changes were observed in major vital organs. A similar study was conducted in Albino Wistar rats, which were sacrificed at the end of 15 days. No histopathological changes or toxicity was observed at up to 2 g/kg body weight. Subacute toxicity was conducted in Albino Wistar rats at a dose of 90 mg/kg body weight for 3 days, then at 180 mg/kg for the next 3 days, and then at 270 mg/kg for 3 weeks. After 28 days, the animals were sacrificed and tested; no toxicity was observed. In a subchronic toxicity study, there was no observed adverse effect level at 1 g/kg body weight in rats. In a teratological assay, at doses of 3.0 g/kg (20 times the recommended dose) and 1.8 g/kg, respectively, no visceral or skeletal anomalies were observed in the fetuses. No maternal changes were observed when Aller-7 was administered during gestation and lactation. No evidence of mutagenicity was observed at doses up to 5000 mug per plate of Aller-7 in Salmonella typhimurium cells. The present study evaluated the safety of Aller-7 by conducting several in vitro and in vivo studies. Further studies of the 90-day chronic toxicity of Aller-7 are currently in progress.

Toxicol Mech Methods. 2003;13(4):253-61