Dapagliflozin Added to Verinurad Plus Febuxostat Further Reduces Serum Uric Acid in Hyperuricemia: The QUARTZ Study

CONTEXT

Combining a sodium-glucose cotransporter 2 inhibitor with a xanthine oxidase inhibitor (XOI) and a urate transporter 1 (URAT1) inhibitor may enhance serum uric acid (sUA) lowering. However, concerns exist regarding high urinary UA (uUA) excretion rates and subsequent crystallization in renal tubules.

OBJECTIVE

To assess whether dapagliflozin added to verinurad, a selective URAT1 inhibitor, and febuxostat, an XOI, increases uUA excretion.

DESIGN

Randomized, placebo-controlled, 2-way crossover study (NCT03316131).

PATIENTS

Adults with asymptomatic hyperuricemia.

INTERVENTIONS

Subjects (N = 36) were randomized to oral once-daily 9 mg verinurad plus 80 mg febuxostat plus 10 mg dapagliflozin for 7 days and 7 days of oral once-daily 9 mg verinurad plus 80 mg febuxostat plus placebo with an intervening 7- to 21-day washout period.

MAIN OUTCOME MEASURE

Difference in peak uUA excretion between groups from baseline to day 7. Secondary outcomes included changes in sUA levels and 24-h uUA excretion.

RESULTS

Both regimens lowered mean peak uUA excretion (least squares mean changes from baseline: -12.9 mg/h [95% confidence interval (CI): -21.0 to -4.7], dapagliflozin; -13.2 mg/h [95% CI -21.3 to -5.0], placebo). sUA concentrations were lower with dapagliflozin (mean treatment difference -62.3 µmol/L [95% CI -82.8 to -41.8]). Dapagliflozin did not impact verinurad pharmacokinetics, its main metabolites, or febuxostat or fasting plasma glucose levels vs verinurad plus febuxostat. There were no clinically relevant changes in safety parameters.

CONCLUSIONS

Dapagliflozin further reduced sUA without influencing uUA excretion, suggesting that its combination with verinurad and febuxostat at the doses tested does not adversely affect kidney function.

CLINICAL TRIAL REGISTRATION NUMBER

NCT03316131.

Association between hyperuricemia, gout, urate lowering therapy, and osteoarthritis: A protocol for a systematic review and meta-analysis

INTRODUCTION

Osteoarthritis (OA), a chronic and degenerative joint disease characterized by articular cartilage degeneration, sclerosis of subchondral bone, and osteophyte formation, is deemed a leading cause of activity limitation and disability among the elderly people. Serum uric acid (UA) is a terminal metabolite of purine compound, while hyperuricemia (HU) and UA crystals are recognized causes of gout. Several studies have investigated the correlations between HU, gout and OA, but the findings are inconclusive. We are also concerned whether the urate lowering therapy (ULT) can become a potential treatment for OA and intend to undertake this meta-analysis to clarify the related hypotheses.

METHODS

Systematic literature search will be conducted on PubMed, Embase, and Web of Science to identify relevant studies up to February 2020 using appropriate search strategies. All citations and abstracts retrieved from literature search will be assessed by two reviewers independently. The Newcastle-Ottawa Scale or the Cochrane risk of bias assessment tool will be used as appropriate to assess the quality and the risk of bias of the included studies. The heterogeneity and the publication bias of the studies will be investigated accordingly.

RESULTS

We propose to undertake this meta-analysis as a feasible approach to clarify the associations between HU, gout or ULT, and OA.

DISCUSSIONS

This meta-analysis will help to strengthen our knowledge of the pathogenesis of OA and promote the development of preventive or treatment strategies.

REGISTRATION

PROSPERO registration number CRD42020168769.

2020 American College of Rheumatology Guideline for the Management of Gout

OBJECTIVE

To provide guidance for the management of gout, including indications for and optimal use of urate-lowering therapy (ULT), treatment of gout flares, and lifestyle and other medication recommendations.

METHODS

Fifty-seven population, intervention, comparator, and outcomes questions were developed, followed by a systematic literature review, including network meta-analyses with ratings of the available evidence according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology, and patient input. A group consensus process was used to compose the final recommendations and grade their strength as strong or conditional.

RESULTS

Forty-two recommendations (including 16 strong recommendations) were generated. Strong recommendations included initiation of ULT for all patients with tophaceous gout, radiographic damage due to gout, or frequent gout flares; allopurinol as the preferred first-line ULT, including for those with moderate-to-severe chronic kidney disease (CKD; stage >3); using a low starting dose of allopurinol (≤100 mg/day, and lower in CKD) or febuxostat (<40 mg/day); and a treat-to-target management strategy with ULT dose titration guided by serial serum urate (SU) measurements, with an SU target of <6 mg/dl. When initiating ULT, concomitant antiinflammatory prophylaxis therapy for a duration of at least 3-6 months was strongly recommended. For management of gout flares, colchicine, nonsteroidal antiinflammatory drugs, or glucocorticoids (oral, intraarticular, or intramuscular) were strongly recommended.

CONCLUSION

Using GRADE methodology and informed by a consensus process based on evidence from the current literature and patient preferences, this guideline provides direction for clinicians and patients making decisions on the management of gout.

A drug-drug interaction study of a novel, selective urate reabsorption inhibitor dotinurad and the non-steroidal anti-inflammatory drug oxaprozin in healthy adult males

Background

Dotinurad is a novel, selective urate reabsorption inhibitor, which reduces serum uric acid levels by inhibiting the urate transporter 1. The results of nonclinical studies indicated the possibility that the concomitant use of the non-steroidal anti-inflammatory drug oxaprozin affects the pharmacokinetics of dotinurad. We evaluated drug–drug interactions with respect to the pharmacokinetics and safety of dotinurad when co-administered with oxaprozin.

Methods

This was an open-label, two-period, add-on study in healthy adult males. For a single dose of 4 mg of dotinurad with and without oxaprozin, we compared its pharmacokinetic parameters and evaluated safety.

Results

This study enrolled 12 subjects, 11 of whom completed the study. The geometric mean ratio (90% confidence interval [CI]) of the urinary excretion rate of glucuronate conjugates of dotinurad after co-administration with oxaprozin compared to administration of dotinurad alone was 0.657 (0.624–0.692), while the geometric mean ratios (90% CIs) of the maximum plasma concentration and area under the plasma concentration–time curve from time zero to infinity (AUC_0–inf) were 0.982 (0.945–1.021) and 1.165 (1.114–1.219), respectively. During the study, two adverse events occurred after administration of dotinurad alone and one occurred after administration of oxaprozin alone.

Conclusions

In comparison with administration of dotinurad alone, co-administration with oxaprozin was associated with a 34.3% decrease in the urinary excretion rate of the glucuronate conjugates of dotinurad, and a 16.5% increase in AUC_0–inf of dotinurad. However, no clinically meaningful drug–drug interactions were observed. Administration of dotinurad alone was similar safety to co-administration with oxaprozin.

Clinical trial registration

ClinicalTrials.gov Identifier: NCT03350386.

Dotinurad versus benzbromarone in Japanese hyperuricemic patient with or without gout: a randomized, double-blind, parallel-group, phase 3 study

Background

Dotinurad is a novel selective urate reabsorption inhibitor that reduces serum urate levels in hyperuricemic patients with or without gout by selectively inhibiting urate transporter 1. This study was conducted to compare the efficacy and safety of dotinurad with those of benzbromarone.

Methods

In this 14-week, randomized, multicenter, double-blind, parallel-group, dose escalation, benzbromarone-controlled, phase 3 study, hyperuricemic patients with or without gout were randomized to two groups that received either dotinurad 2 mg or benzbromarone 50 mg. Dotinurad or benzbromarone was administered once a day for 14 weeks. The primary endpoint was the percent change in serum uric acid level from the baseline to the final visit.

Results

A total of 201 Japanese hyperuricemic patients with or without gout (dotinurad: 102, benzbromarone: 99) received at least one dose of the study drug. The mean percent change in serum uric acid level from the baseline to the final visit in the dotinurad and benzbromarone groups was 45.9% and 43.8%, respectively. Non-inferiority of dotinurad 2 mg to benzbromarone 50 mg in lowering serum uric acid was verified by the predefined non-inferiority margin (95% CI − 1.27 to 5.37%). The incidence of adverse events and adverse drug reactions was comparable between the two groups.

Conclusion

Dotinurad 2 mg was verified to have a non-inferior serum uric acid lowering effect compared with benzbromarone 50 mg, in Japanese hyperuricemic patients with or without gout.

ClinicalTrials.gov Identifier

NCT03100318.

Individualized treatment strategies for hyperuricemia informed by a semi-mechanistic exposure-response model of uric acid dynamics

To provide insight into pharmacological treatment of hyperuricemia we developed a semi-mechanistic, dynamical model of uric acid (UA) disposition in human. Our model represents the hyperuricemic state in terms of production of UA (rate, PUA), its renal filtration (glomerular filtration rate, GFR) and proximal tubular reabsorption (fractional excretion coefficient, FE). Model parameters were estimated using data from 9 Phase I studies of xanthine oxidase inhibitors (XOI) allopurinol and febuxostat and a novel uricosuric, the selective UA reabsorption inhibitor lesinurad, approved for use in combination with a XOI. The model was qualified for prediction of the effect of patients' GFR and FE on concentration of UA in serum (sUA) and UA excretion in urine and their response to drug treatment, using data from 2 Phase I and 4 Phase III studies of lesinurad. Percent reduction in sUA from baseline by a XOI is predicted to be independent of GFR, FE or PUA. Uricosurics are more effective in underexcreters of UA or patients with normal GFR. Co-administration of a XOI and an uricosuric agent should be considered for patients with high sUA first in the treatment algorithm of gout before uptitration of XOI. The XOI dose in combination with a uricosuric can be reduced compared to XOI alone for the same target sUA to the degree dependent on patient's GFR and FE. This exposure-response model of UA can be used to rationally select the best drug treatment option to lower elevated sUA in gout patients under differing pathophysiological situations.

Allopurinol reduces the lethality associated with acute renal failure induced by Crotalus durissus terrificus snake venom: comparison with probenecid

Background

Acute renal failure is one of the most serious complications of envenoming resulting from Crotalus durissus terrificus bites. This study evaluated the relevance of hyperuricemia and oxidative stress and the effects of allopurinol and probenecid in renal dysfunction caused by direct nephrotoxicity of C. d. terrificus venom.

Methodology/Principal Findings

Hematocrit, protein, renal function and redox status were assessed in mice. High ratio of oxidized/reduced glutathione and hyperuricemia induced by C. d. terrificus venom were ameliorated by both, allopurinol or probenecid, but only allopurinol significantly reduced the lethality caused by C. d. terrificus venom. The effectiveness of probenecid is compromised probably because it promoted hypercreatinemia and hypocreatinuria and worsed the urinary hypo-osmolality in envenomed mice. In turn, the highest effectiveness of allopurinol might be due to its ability to diminish the intracellular formation of uric acid.

Conclusions/Significance

Data provide consistent evidences linking uric acid with the acute renal failure induced by C. d. terrificus venom, as well as that this envenoming in mice constitutes an attractive animal model suitable for studying the hyperuricemia and that the allopurinol deserves to be clinically evaluated as an approach complementary to anti-snake venom serotherapy.

In Brazil, among registered snake bites, those by the genus Crotalus originate the highest mortality rate. The rattlesnake Crotalus durissus terrificus is the most frequently implicated in these accidents. The kidney is a particularly vulnerable organ to the venom of this rattlesnake. In fact, the most serious complication of Crotalus snake bite is the renal dysfunction, and among the fatal cases of Crotalus bites in Brazil 5% are patients treated with antivenom. The hyperuricemia has been observed in human accidents with snake venoms, but this parameter has not received any special attention as a relevant factor in the etiology of renal dysfunction caused by these venoms. This study examined the effects of treatments with low-cost and low-risk uricostatic (allopurinol) and uricosuric (probenecid) drugs on the envenomation by C. d. terrificus, showing that allopurinol and probenecid mitigated certain nephrotoxic effects, as well as the survival of envenomed mice was improved through the effects of allopurinol on reduction of oxidative stress and intracellular formation of uric acid. This new knowledge provides consistent evidences linking uric acid with the renal dysfunction induced by rattlesnake bites and that the allopurinol deserves to be clinically evaluated as an approach complementary to anti-snake venom serotherapy.

Prevalence of contraindications and prescription of pharmacologic therapies for gout

BACKGROUND

Patients with gout have comorbidities, but the impact of these comorbidities on treatment has not been studied.

METHODS

A total of 575 patients with gout were stratified according to certainty of diagnosis according to International Classification of Diseases, 9th Revision, Clinical Modification code alone (cohort I), American College of Radiology criteria (cohort II), and crystal diagnosis (cohort III). Comorbid conditions were defined according to International Classification of Diseases, 9th Revision, Clinical Modification codes, and stratified as either moderate or severe. Drug contraindications were defined as moderate or strong, based on Food and Drug Administration criteria and severity of disease.

RESULTS

The most common comorbidity was hypertension (prevalence 0.89). The presence of comorbidities resulted in a high frequency of contraindications to approved gout medications. More than 90% of patients had at least 1 contraindication to nonsteroidal anti-inflammatory drugs. Many patients demonstrated multiple contraindications to 1 or more gout medications. Frequently, patients were prescribed medications to which they harbored contraindications. The prevalence of patients prescribed colchicine despite having at least 1 strong contraindication was 30% (cohort I), 37% (cohort II), and 39.6% (cohort III).

CONCLUSION

Patients with gout typically harbor multiple comorbidities that result in contraindications to many of the medications available to treat gout. Frequently, despite contraindications to gout therapies, patients are frequently prescribed these medications.

Impact of noncompliance with urate-lowering drug on serum urate and gout-related healthcare costs: administrative claims analysis

OBJECTIVE

To determine the association between allopurinol compliance and serum urate (sUA) level; and examine the association between sUA and gout-related healthcare costs in a large managed care population.

RESEARCH DESIGN AND METHODS

This retrospective administrative claims analysis examined subjects with gout (> or = 2 medical claims with ICD-9-CM diagnosis code 274.xx or > or = 1 claim with a gout diagnosis and > or = 1 pharmacy claim for allopurinol, probenecid, colchicine, or sulfinpyrazone) between January 1, 2002 and March 31, 2004. Each subject was observed during 1-year pre-index and 1-year post-index periods.

MAIN OUTCOME MEASURES

Outcomes were allopurinol medication possession ratio (MPR) and compliance (MPR > or = 0.80), sUA (mg/dL), and gout-related healthcare costs. 'Post-allopurinol' sUA was measured during three periods after the first observed allopurinol fill: 30-89 days; 90-149 days; > or = 150 days. A baseline sUA on or before the start of the post-index period was also identified. Outcomes were stratified by post-allopurinol or baseline sUA and compliance. Generalized linear modeling (GLM) regression measured the impact of baseline sUA on gout-related healthcare costs, controlling for demographic and health status variables.

RESULTS

The study sample comprised 18,243 subjects with mean age of 53.9 years. In all, 55% (n = 10,073) of subjects used allopurinol. There were 1473 (8.1%) subjects with a post-allopurinol sUA and 2438 (13.4%) subjects with a baseline sUA result. Among all subjects with a post-allopurinol sUA, 45.6% were compliant; between 49.3% and 56.8% of compliant subjects had an sUA < 6.0 mg/dL compared with 22.5-27.8% of non-compliant subjects, depending on the post-allopurinol time period (all p < 0.001). GLM results showed gout-related costs associated with baseline sUA > or = 6.0 and < 9.0 mg/dL were 58% higher (95% confidence interval (CI): 1.012 -2.456; p = 0.044) than were costs for sUA < 6.0 mg/dL. There was no significant difference in gout-related costs between baseline sUA < 6.0 mg/dL and > or = 9.0 mg/dL.

CONCLUSIONS

Analysis revealed an important associations between allopurinol compliance, sUA, and gout-related costs: compliance was positively associated with favorable sUA (<6.0 mg/dL) in unadjusted comparisons. GLM showed that baseline sUA < 6.0 was inversely associated with gout-related costs relative to baseline sUA > or = 6.0 and <9.0 mg/dL. Nevertheless, a substantial portion of subjects, even compliant ones, did not achieve sUA < 6.0 mg/dL. These results should be interpreted carefully in light of study limitations, including incomplete laboratory data, the potentially incorrect inference that medications were taken as prescribed, and lack of generalizability from Medicare managed care enrollees to the broader Medicare population.

Multidrug resistance-associated protein 2 (MRP2) affects hepatobiliary elimination but not the intestinal disposition of tenofovir disoproxil fumarate and its metabolites

The role of multidrug resistance-associated protein 2 (MRP2) on the intestinal disposition and hepatobiliary elimination of tenofovir disoproxil fumarate (DF) and its metabolites [tenofovir (mono)ester and tenofovir] was studied in the Caco-2 system, Ussing chambers and rat in-situ efflux experiments. In the Caco-2 model and Ussing chambers, no statistically significant differences in transport could be observed when the MRP inhibitor probenecid was included. In Ussing chambers, transport was also similar when using intestinal tissue from MRP2-deficient rats. After intravenous administration of tenofovir DF, the excretion of tenofovir [(mono)ester] in bile was significantly decreased in MRP2-deficient rats and in rats treated with probenecid. The area under the blood concentration-time curve was increased in MRP2-deficient rats [1.0+/-0.1 and 0.36+/-0.03 microM.min-1 for tenofovir and tenofovir (mono)ester, respectively] and rats treated with probenecid (1.42+/-0.04 and 0.36+/-0.02 microM.min-1) compared with control rats (0.64+/-0.05 and 0.15+/-0.06 microM.min-1). The appearance of tenofovir [(mono)ester] in intestinal perfusate was similar in control rats upon co-administering probenecid or when using MRP2-deficient rats. In conclusion, MRP2 appeared to have no modulatory effect on the intestinal disposition of tenofovir and tenofovir (mono)ester. However, inhibition (probenecid) or the total absence of MRP2 (MRP2-deficient rats) significantly reduced hepatobiliary elimination, which was accompanied by increased systemic exposure.

[Uricosuric agent]

Urate lowering treatment is indicated in patients with recurrent acute attacks, tophi, gouty arthropathy, radiographic changes of gout, multiple joint involvement, or associated uric acid nephrolithiasis. Uricosuric agents like benzbromarone and probenecid are very useful to treat hyperuricemia as well as allopurinol (xanthine oxidase inhibitor). Uricosuric agents act the urate lowering effect through blocking the URAT1, an urate transporter, in brush border of renal proximal tubular cells. In order to avoid the nephrotoxicity and urolithiasis due to increasing of urinary urate excretion by using uricosuric agents, the proper urinary tract management (enough urine volume and correction of aciduria) should be performed.

Antihyperuricemic lignans from the leaves of Phyllanthus niruri

The methanol extract from the leaves of Phyllanthus niruri L. showed oral antihyperuricemic activity in potassium oxonate- and uric acid-induced hyperuricemic rats. Fractionation of the extract by resin chromatography led to the isolation of a less polar fraction which exhibited the highest reduction of plasma uric acid. Further antihyperuricemic-guided purification of the fraction afforded three lignans, phyllanthin (1), hypophyllanthin (2) and phyltetralin (3), of which 1 significantly reversed the plasma uric acid level of hyperuricemic animals to its normal level in a dose-dependent manner, comparable to that of allopurinol, benzbromarone and probenecid which are used clinically for the treatment of hyperuricemia and gout. Thus, the lignans of P. niruri are potential antihyperuricemic agents worthy of further investigation.

Effect of fenofibrate in combination with urate lowering agents in patients with gout

BACKGROUND

To assess the efficacy of fenofibrate treatment in combination with urate lowering agents in patients with gout.

METHODS

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 > or = 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.

RESULTS

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.

CONCLUSIONS

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.

Quantitative analysis of the effect of probenecid on pharmacokinetics of 99mTc-mercaptoacetyltriglycine in dogs

Effect of probenecid on pharmacokinetics of 99mTc-mercaptoacetylytriglycine (99mTc-MAG3) in dogs was investigated before (control), and after 15 min and 24 h of i.v. injection of probenecid (20 mg/kg). Plasma concentration-time profiles of 99mTc-MAG3 were described with a two-compartment open model. Plasma 99mTc-MAG3 clearances (Clp, ml/min/kg) were 7.9 +/- 0.5, 3.3 +/- 0.5 and 4.8 +/- 1.3 in control, 15 min and 24 h after probenecid administration respectively. Similarly, the biological half-lives at elimination phase (t(1/2), h) were 0.61 +/- 0.09, 0.79 +/- 0.11 and 0.74 +/- 0.12, and volumes of distribution at steady state (Vdss, L/kg) were 0.29 +/- 0.04, 0.20 +/- 0.05 and 0.25 +/- 0.06 respectively. The prolonged biological half-life and decreased Vdss decreased Clp significantly. Clp was a function of plasma probenecid concentration based on Michaelis-Menten kinetics. The maximum Clp inhibition (Imax) by probenecid and the plasma probenecid concentration that induced 50% of Imax (I50) were estimated to be 72 +/- 12% and 13 +/- 8 microg/ml respectively. This means that the rest (about 28%) of the Clp is not blocked by probenecid alone, suggesting the possibility of another route(s) of elimination or renal transporters which are independent from probenecid. Moreover, inter-species correlation between Clp of 99mTc-MAG3 and body weight are discussed.

An update on the treatment options for gout and calcium pyrophosphate deposition

Gout and calcium pyrophosphate deposition disease are two common causes of inflammatory joint disease. Despite differences underlying their pathogenesis, their clinical presentation and treatment share some common features. Optimal treatment for both requires prompt resolution of acute synovitis, reduction of chronic joint damage and management of associated conditions. Available therapeutic interventions and future strategies are reviewed in this article.

Effect of probenecid on the pharmacokinetics of carbamazepine in healthy subjects

OBJECTIVES

Carbamazepine (CBZ) undergoes biotransformation by CYP3A4 and CYP2C8, and glucuronide conjugation. There has been no clear demonstration to reveal the role of glucuronidation in the disposition of CBZ. We evaluated the effect of probenecid, a UDP-glucuronosyltransferase inhibitor, on the pharmacokinetics of CBZ in humans.

METHODS

In a randomized, open-label, two-way crossover study, ten healthy male subjects were treated twice daily for 10 days with 500 mg probenecid or with a matched placebo. On day 6, a single dose of 200 mg CBZ was administered orally. Concentrations of CBZ and CBZ 10,11-epoxide (CBZ-E) in plasma and urine were measured.

RESULTS

Probenecid decreased the area under the plasma concentration-time curve (AUC) of CBZ from 1253.9 micromol h/l to 1020.7 micromol h/l (P < 0.001) while increasing that of CBZ-E from 137.6 micromol h/l to 183.5 micromol h/l (P = 0.033). The oral clearance of CBZ was increased by probenecid by 26% (90% confidence interval, 17-34%; P < 0.001). Probenecid increased the AUC ratio of CBZ-E/CBZ from 0.11 to 0.16 (P < 0.001). However, probenecid had minimal effect on the recovery of the conjugated and free forms of CBZ and CBZ-E in urine.

CONCLUSION

Although probenecid showed a minimal effect on the glucuronidation of CBZ and CBZ-E, it increased CBZ biotransformation to CBZ-E, most likely reflecting the induction of CYP3A4 and CYP2C8 activities, in humans. These results demonstrate that glucuronide conjugation plays a minor role in the metabolism of CBZ and CBZ-E in humans, and that probenecid has an inducing effect on the disposition of CBZ.

Systemically administered glucosamine-kynurenic acid, but not pure kynurenic acid, is effective in decreasing the evoked activity in area CA1 of the rat hippocampus

The metabolism of tryptophan along the kynurenine pathway yields several neuroactive intermediates, including kynurenic acid, which is one of the few known endogenous N-methyl-d-aspartate receptor inhibitors; in parallel with this, it is an alpha7 nicotinic acetylcholinergic receptor antagonist. On the basis of these properties, kynurenic acid might therefore come into consideration as a therapeutic agent in certain neurobiological disorders. However, the use of kynurenic acid as a neuroprotective agent is practically excluded because kynurenic acid hardly crosses the blood-brain barrier. We recently synthetized a new compound, glucosamine-kynurenic acid, which is presumed to cross the blood-brain barrier more easily. In this study, the effects of systemically administered kynurenic acid and glucosamine-kynurenic acid on CA3 stimulation-evoked population spike activity in region CA1 of the rat hippocampus were compared. The effect of kynurenic acid or glucosamine-kynurenic acid was augmented by probenecid (200 mg/kg), which inhibits kynurenic acid excretion from the cerebrospinal fluid. The results showed that, while kynurenic acid administered i.p. or i.v. in doses of 17, 34, 68 or 136 micromol/kg did not cause any observable change in the animals, 136 micromol/kg glucosamine-kynurenic acid (either i.p. or i.v.) resulted in the sudden death of all the animals. The dose of 68 micromol/kg i.v., but not i.p., resulted in a sudden stoppage of breath, but the animals could be reanimated. As small a dose of glucosamine-kynurenic acid as 17 micromol/kg i.p. resulted in a reduction in population spike amplitudes; this effect was further augmented by probenecid, whereas neither 17 micromol/kg nor higher doses of pure kynurenic acid had a similar effect. The results presented here suggest that glucosamine-kynurenic acid passes the blood-brain barrier much more readily than does kynurenic acid.

Counteraction of oxalate induced nitrosative stress by supplementation of l-arginine, a potent antilithic agent

BACKGROUND

Our understanding of nitrosative stress in the process of urolithiasis is far from complete. Earlier studies carried out in our laboratory demonstrate the presence of nitrated THP in stone formers, l-arginine (l-arg) a precursor of nitric oxide (NO), attenuates the endothelial dysfunction caused by reactive nitrogen species. We investigated the role of l-arg in ethylene glycol (EG)-induced urolithic rat model and observed its antilithic and antioxidative properties.

METHODS

Hyperoxaluria was induced using 0.75% EG in drinking water. l-arg [1.25 g/kg body weight] was given orally for a period of 28 days.

RESULTS

EG-treated rats showed significant loss in body weight and increase in the activities of oxalate synthesizing enzymes such as glycollic acid oxidase in liver. Lactate dehydrogenase activity in liver and kidney was increased. The activity of the free radical producing enzyme xanthine oxidase, tissue oxalate and calcium levels were significantly increased in EG-treated rats. Depletion in the antioxidant enzymes, membrane bound ATPases and thiol status was observed in these rats. l-arg co-supplementation to EG-treated rats maintained the activities of the oxalate synthesizing enzymes and free radical producing enzymes with in the normal range. Tissue oxalate and calcium levels were also maintained near normal in l-arg treated hyperoxaluric rats. l-arg, by its cytoprotective effect, maintained the thiol status, thereby preserving the activities of the membrane bound ATPases and preventing proteinuria and subsequent weight loss in EG-treated rats.

CONCLUSION

l-arg feeding prevents the retention of calcium oxalate crystals in hyperoxaluric rats by way of protecting the renal cells from oxidative injury and also by providing a second line of defense through the normalization of the oxalate metabolism. It reduces the risk of stone formation, by curtailing free radicals and hyperoxaluria as both of them have to work in close association to form stones.

Hypouricemic action of scopoletin arising from xanthine oxidase inhibition and uricosuric activity

Scopoletin exhibited an immediate and dose-dependent hypouricemic effect after intraperitoneal administration (50, 100, 200 mg/kg) in hyperuricemic mice induced by potassium oxonate; however, it did not affect the serum uric acid level in normal mice at the tested doses. For exploring the involved mechanisms of action of scopoletin, potential inhibitory effects on xanthine oxidase and possible uricosuric effects were investigated. Scopoletin (50, 100, 200 mg/kg) significantly inhibited the activity of xanthine oxidase in liver homogenates of hyperuricemic mice although it only showed a relatively weak, albeit competitive-type, inhibition of xanthine oxidase in a commercial assay. Furthermore, a potent uricosuric effect of scopoletin (100, 200 mg/kg) was ascertained. These results demonstrated for the first time that scopoletin exhibits, hypouricemic activities through decreasing uric acid production and as well as a uricosuric mechanism.

The efficacy of combined low dose of Allopurinol and benzbromarone compared to standard dose of Allopurinol in hyperuricemia

OBJECTIVE

To compare the efficacy of combined low dose of hypouricemic drugs (Allopurinol 100 mg and benzbromarone 20 mg; Allomaron) and standard dose 300 mg of allopurinol in hyperuricemia.

MATERIAL AND METHOD

A prospective, open study of 94 hyperuricemic patients was done at King Chulalongkorn Memorial Hospital. Each group of 47 patients was given a combined low dose of hypouricemic drugs (Allopurinol 100 mg and benzbromarone 20 mg; Allomaron) and a standard dose 300 mg of allopurinol. Serum uric acid was measured before and 4 weeks after receiving the drugs. The efficacy was measured from the difference of the level of serum uric acid before and after receiving the drugs.

RESULTS

The patients receiving the combined low dose of hypouricemic drugs and standard dose of allopurinol showed a mean reduction of serum uric acid of 2.5+/-3.4 mg/dl and 4.1+/-2.7 mg/dl consecutively. There was a statistically significant difference between the 2 groups (P = 0.010).

CONCLUSION

This study demonstrates that the efficacy of standard dose 300 mg of allopurinol is superior to a combined low dose of allopurinol and benzbromarone in lowering the level of serum uric acid level.

Lebensbedrohliche Nebenwirkungen der Gichtbehandlung

Die Behandlung der Gicht mit Allopurinol kann schwere unerwünschte Wirkungen zur Folge haben. Neben dem häufigen Hautausschlag unter Allopurinol kann ein selteneres Hypersensitivitäts-Syndrom mit Fieber, Hautexanthem (bis zum Lyell-Syndrom), Hepatopathie, Eosinophilie, Niereninsuffizienz und Vaskulitis lebensbedrohlich sein. Die Inzidenz dieser schweren Nebenwirkung kann wahrscheinlich mit einer der Nierenfunktion angepassten Reduktion der Dosis von Allopurinol gesenkt werden. Da Azathioprin und Mercaptopurin über die Xanthinoxidase, die durch Allopurinol gehemmt wird, metabolisiert werden, kann es bei gleichzeitiger Verabreichung zu lebensbedrohlichen Neutropenien kommen, wenn die Dosis des Allopurinols nicht um zirka 75% reduziert wird. Das urikosurisch wirkende Benzbromaron wurde kürzlich wegen schwerer Leberschädigungen vom Markt genommen.

Probenecid-induced changes in the clearance of pranoprofen enantiomers

Probenecid is known to inhibit the elimination of several acidic drugs. Its influence on the pharmacokinetics of pranoprofen was investigated in rabbit after a single intravenous injection of racemic mixture (5 mg/kg). Levels of (-)-(R)- and (+)-(S)-pranoprofen and their glucuronide (after hydrolysis with sodium hydroxide) were determined in plasma, urine, and several tissues. The plasma concentration of the (+)-(S)-isomer was higher than that of the (-)-(R)-form. Oral coadministered probenecid (100 mg/kg) resulted in an increased plasma concentration of both enantiomers. Probenecid reduced the apparent total clearance and excretion of pranoprofen enantiomers in urine. It had a slight effect on the tissue distribution of pranoprofen at the dose used, but significantly reduced the formation of glucuronide for both enantiomers to the same extent in kidney microsomes. The differences caused by probenecid were significant with respect to its ability to inhibit glucuronidation in the kidney and subsequent excretion into urine, but enantioselective effects were negligible.

Efficacy of benzbromarone compared to allopurinol in lowering serum uric acid level in hyperuricemic patients

This study was aimed to evaluate the efficacy of benzbromarone compared to allopurinol in lowering serum uric acid level in hyperuricemic patients with normal renal function (serum creatinine < or = 1.5). The authors conducted a crossover study consisting of two four-week treatment periods of allopurinol 300 mg/day and benzbromarone 100 mg/day separated by a four-week washout period. Fourteen patients with mean age and duration of hyperuricemia of 60.78 +/- 8.62 and 6.93 +/- 3.69 years, respectively, were recruited and all completed our study protocol. This study was a crossover design consisting of two four-week treatments of allopurinol and benzbromarone separated by a four-week washout period. The serum uric acid level was reduced from 9.89 +/- 1.43 mg/dl to 5.52 +/- 0.83 mg/dl and from 9.53 +/- 1.48 to 4.05 +/- 0.87 mg/dl by allopurinol and benzbromarone, respectively. The efficacy of benzbromarone in lowering serum uric acid level was significantly superior to allopurinol (p=0.005). No patient reported clinical side effects during treatment with either drug. In conclusion, the authors have shown that benzbromarone is more effective than allopurinol in the reduction of serum uric acid levels in hyperuricemic patients with normal renal function.

Pharmacokinetics of enrofloxacin and its metabolite ciprofloxacin in goats given enrofloxacin alone and in combination with probenecid

The pharmacokinetics of enrofloxacin and its active metabolite ciprofloxacin were investigated in goats given enrofloxacin alone or in combination with probenecid. Enrofloxacin was administered i.m. at a dosage of 5 mg x kg(-1) alone or in conjunction with probenecid (40 mg x kg(-1), i.v.). Blood samples were drawn from the jugular vein at predetermined time intervals after drug injection. Plasma was separated and analysed simultaneously for enrofloxacin and ciprofloxacin by reverse-phase high performance liquid chromatography. The plasma concentration-time data for both enrofloxacin and ciprofloxacin were best described by a one-compartment open pharmacokinetic model. The elimination half-life (t(1/2beta)), area under the plasma concentration-time curve (AUC), volume of distribution (V(d(area))), mean residence time (MRT) and total systemic clearance (Cl(B)) were 1.39 h, 7.82 microg x h x mL, 1.52 L x kg(-1), 2.37 h and 802.9 mL x h(-1) x kg(-1), respectively. Enrofloxacin was metabolized to ciprofloxacin in goats and the ratio between the AUCs of ciprofloxacin and enrofloxacin was 0.34. The t(1/2beta), AUC and MRT of ciprofloxacin were 1.82 h, 2.55 microg x h x mL and 3.59 h, respectively. Following combined administration of probenecid and enrofloxacin in goats, the sum of concentrations of enrofloxacin and ciprofloxacin levels > or = 0.1 microg x mL(-1) persisted in plasma up to 12 h.Co-administration of probenecid did not affect the t(1/2beta), AUC, V(d (area)) and Cl(B) of enrofloxacin, whereas the values of t(1/2beta) (3.85 h), AUC (6.29 microg x h x mL), MRT (7.34 h) and metabolite ratio (0.86) of ciprofloxacin were significantly increased. The sum of both enrofloxacin and ciprofloxacin levels was > or = 0.1 microg x mL(-1) and was maintained in plasma up to 8 h in goats after i.m. administration of enrofloxacin alone. These data indicate that a 12 h dosing regime may be appropriate for use in goats.

Treatment of calcinosis in juvenile dermatomyositis with probenecid: the role of phosphorus metabolism in the development of calcifications

OBJECTIVE

To report the efficacy of probenecid for calcinosis of juvenile dermatomyositis (JDM) and assess the changes in phosphorus metabolism during treatment.

METHODS

Biochemical studies of calcium and phosphorus metabolism were performed in a 9-year-old girl with JDM and extensive calcifications before and during probenecid treatment.

RESULTS

The calcifications resolved over 18 months of treatment. Probenecid was found to be effective in reducing calcifications by increasing renal phosphate clearance.

CONCLUSIONS

The tendency for calcifications in some patients with JDM might be related to an increase in renal phosphate reclamation, and therefore, probenecid treatment may be effective in these patients.

Improvement of renal function in patients with chronic gout after proper control of hyperuricemia and gouty bouts

AIM

To evaluate the effect of nonsteroidal anti-inflammatory drug (NSAID) withdrawal on renal function in patients with chronic gout after proper control of hyperuricemia and gouty symptoms.

METHODS

Patients with chronic gout, who regularly used NSAIDs to control gouty symptoms prior to urate-lowering therapy, were prospectively followed up in an observational study. Risk factors for renal function impairment were recorded, and the clearance of creatinine (Ccr) was initially measured while on colchinine therapy to prevent gouty bouts. Therapy with urate-lowering drugs was started in order to keep serum urate levels under 6.0 mg/dl (275 micromol/l), and the Ccr was monitored during the follow-up period. Final assessment of the renal function was made after 1 year free from gouty bouts and without NSAID therapy during this period.

RESULTS

87 patients completed a 1-year period of NSAID withdrawal. Low initial Ccr was related to age, hypertension, hypertriglyceridemia and the presence of previous renal diseases. After proper control of gout and NSAID withdrawal during 1 year, the mean Ccr significantly raised from 94 to 104 ml/min. The improvement was especially significant in patients whose initial Ccr was under 80 ml/min. Their mean Ccr rose from 60 to 78 ml/min, and 12 of 29 patients achieved normal Ccr at the end of the study. No risk factor correlated with improvement of the renal function.

CONCLUSIONS

Renal function impairment in patients with chronic gout is mainly related to vascular risk factors, but improvement of the renal function was observed after proper control of hyperuricemia and NSAID withdrawal. Optimal control of hyperuricemia and, therefore, of symptoms of gout should be especially considered in patients with vascular risk factors in order to avoid renal function loss due to NSAID use.

Effect of application volume of ethanol-isopropyl myristate mixed solvent system on permeation of zidovudine and probenecid through rat skin

Permeation of zidovudine (AZT) and probenecid from an ethanol-isopropyl myristate (IPM) mixed system through rat skin was studied in a finite system. Several volume sizes of the ethanol-IPM mixed systems containing AZT and probenecid, both as suspensions, were applied on the skin of the hairless rat using a vertical glass cell, and the fractions of the drugs permeated in 8 hr Q%,8 hr were determined. For the systems containing 40% ethanol, the Q%,8 hr value decreased with the reduction of volume of the system applied, and the decreasing profile was similar to that calculated on the assumption that the permeability of the drug does not change with the volume of the sample applied. On the other hand, in the systems containing 10% or 20% ethanol, the Q%,8 hr value showed a maximum when a specific volume of the sample was applied. Therefore, the effect of sample volume on the Q%,8 hr value was different between the 40% ethanol-IPM system and the 10% or 20% ethanol-IPM system. Following pretreatment of the skin with 0.105 ml/cm2 of drug-free 40% ethanol-IPM for 2 hr, several volume sizes of 10% ethanol-IPM systems containing the drugs were applied on the skin to explain why the different profiles were observed in the system containing 10% or 20% ethanol. The results for pretreated skin suggest that the amount of ethanol in the systems with low ethanol concentration and small application volume is too small to exert an effect that enhances permeation of the drugs. In those systems, the integrated effect of ethanol on the skin would be important for the enhancing effect. Total volume, as well as concentration, of an enhancer should be set precisely in designing an efficient transdermal delivery system.

Cefaclor, an alternative to third generation cephalosporins for the treatment of gonococcal urethritis in the developing world?

OBJECTIVE

To reassess the in vivo and in vitro efficacy of cefaclor for the treatment of uncomplicated gonococcal infection.

DESIGN

Open clinical trail conducted in South Africa among consecutive male patients with symptoms and signs of uncomplicated urethritis and laboratory evidence of gonorrhoea.

METHODS

Patients were treated with 3 g of cefaclor plus 1 g probenecid as a single dose. Urethral specimens were cultured for Neisseria gonorrhoeae at the initial visit and at follow up. Patients were considered cured if follow up cultures were negative. Treatment was considered to have failed in the patients infected with identical gonococcal strains at the initial and at the control visit. Those with evidence of infection at the follow up visit were administered 400 mg of ofloxacin and doxycycline 100 mg twice daily for 7 days. Minimal inhibitory concentrations (MICs) of cefaclor were determined by an agar dilution technique on the gonococcal isolates from the study subjects. The results were compared with those of isolates from three other African countries.

RESULTS

Of 155 patients evaluated, 151 were cured (97%). Thirty per cent of the patients complained of adverse effects, mainly gastrointestinal. Even though MICs for the isolates from the three other African countries were significantly higher than those for the isolates from the study, none was considered resistant to cefaclor in vitro. MICs were markedly influenced by the type of test medium used.

CONCLUSION

The trial demonstrated the efficacy of a single oral dose of cefaclor with probenecid for the treatment of uncomplicated gonococcal urethritis in South Africa. Its potential as an alternative therapy to third generation cephalosporins deserves to be further investigated.

[How to select and use urate lowering agents for hyperuricemia]

Two classes of urate lowering agents, i.e. uricosuric agents and allopurinol, are available for the treatment of hyperuricemia. To prevent the formation of urinary urate stones and possible damage to liver function, it is recommended to use uricosuric agents in those patients with underexcretion of urate, and allopurinol in those with overproduction. Urinary uric acid/creatinine ratio is a convenient index to determine these phenotypes. These agents should be started to prescribe from the minimal dose to prevent the gouty arthritis which is easily evoked in the first several months after the introduction of these agents. An uric acid level between 5.0 and 6.4 mg/dl had minimal occurence of gouty attack during the first six months of the drug therapy.

Intravenous infusion of diltiazem causes uricosuria with concomitant hypouricemia in rats

The effects of the continuous intravenous infusion of diltiazem on plasma urate levels and the urinary excretion of urate were examined in urethane anesthetized oxonate-loaded rats. The intravenous infusion of diltiazem (4 or 10 mu g/rat/min) caused a gradual decrease in blood pressure, a gradual increase in renal blood flow and a transient increase in glomerular filtration rate. This infusion also caused diuresis, natriuresis, uricosuria and definite hypouricemia. Our results show that diltiazem infused i.v. has uricosuric and hypouricemic effects.

Effect of probenecid on the distribution, metabolism, and excretion of cidofovir in rabbits

The effect of concomitant probenecid on the tissue distribution, metabolism, and urinary excretion of cidofovir was examined in New Zealand white rabbits. Two groups of six male rabbits received intravenous [3H]cidofovir (5 mg/kg, 20 mu Ci/kg) alone or with concomitant intravenous probenecid (90 mg/kg). Radioactivity in kidney at 15 min postdose was decreased 70% by probenecid; plasma levels at 15 min postdose were increased 65% by probenecid. These effects were diminished at later time points. The estimated elimination half-life of cidofovir from the kidney was 16 hr in the presence of probenecid and 11 hr without probenecid. Two additional groups of six rabbits received intravenous [14C]cidofovir (15 mg/kg, 100 mu Ci/kg) alone or 1 hr after oral administration of probenecid (90 mg/kg). Radioactivity was highest in the kidney (approximately 700 mu g-eq/g at 30 min postdose). Probenecid did not affect the gross distribution of radioactivity. However, autoradiography of left kidneys revealed localization of the drug in the renal cortex; radioactivity in the cortex at 30 min postdose was decreased 50% by probenecid. These data are consistent with inhibition of tubular secretion of cidofovir by probenecid. More than 73% of the cidofovir dose was recovered in the urine in 24 hr. Urine contained unchanged cidofovir (>97%) and a metabolite coeluting with authentic cidofovir phosphocholine (2%). This metabolite also accounted for approximately 1-4% of the radioactivity in rabbit kidney.

Biotransformation and uric acid lowering effect of benzbromarone in patients with liver cirrhosis - evidence for active benzbromarone metabolites?

The disposition of benzbromarone and its uric acid lowering effect were investigated in 8 patients with compensated liver cirrhosis in order to obtain evidence whether dose requirements differ from subjects with normal liver function. Following a single oral dose of 100 mg benzbromarone, the plasma concentrations of the parent drug and the two hydroxylated main metabolites M1 and M2 as well as uric acid were determined up to at least 72 h. All patients were found to be rapid benzbromarone eliminators. In patients 2-8 the extent of systemic availability of benzbromarone, as estimated by the average AUC(0-infinite), was similar to previous observations in healthy individuals, whereas the values of both metabolites M1 and M2 tended to be lower in patients with liver cirrhosis. Cmax of benzbromarone and M1 also were lower in patients, M2 was equivalent to the data in subjects with normal liver function. tmax and the plasma elimination half-life t(1/2) varied within the same range as previously observed in healthy individuals. One patient exhibited much higher values in AUC(0-infinite); and Cmax of benzbromarone and both metabolites, and in addition of the elimination half-life of M1 and M2, whereas the plasma elimination of benzbromarone itself was not delayed. An effect of altered liver function cannot be excluded in this patient. Ten hours after benzbromarone administration the mean plasma uric acid in patients 2-8 was reduced by 31.5% and in patient 1 by 44.2% as compared to pretreatment values. Baseline levels were not regained until 72 h. These data are compatible with a prolonged uric acid lowering effect of an active benzbromarone metabolite. Altogether, the present observations do not suggest dose adjustment to be necessary in patients with compensated liver cirrhosis Child A and B.

Withdrawal of longterm antihyperuricemic therapy in tophaceous gout

OBJECTIVE

To determine the effect of withdrawal of antihyperuricemic therapy on the recurrence of tophi and acute arthritis.

METHODS

We performed a retrospective investigation of 21 patients with tophaceous gout who stopped therapy because they had no arthritis for years, and on examination tophi had disappeared.

RESULTS

Nine patients (43%) had a recurrence of tophi after an average period of 39.6 months (range 4-107 months). Seventeen patients (81%) had attacks of acute arthritis, 6 patients within 6 months. During a mean period of drug discontinuation of 37.6 months no increase in serum creatinine or deterioration in joint function was observed.

CONCLUSION

Based on our data we conclude that intermittent usage of antihyperuricemic drugs will, after a variable period, result in the frequent recurrence of acute arthritis and tophi.

Diuretic and uricosuric effects of traxanox sodium in healthy subjects. Single dose study

A new compound, 9-chloro-5-oxo-7-(1H-tetrazol-5-yl)-5H-[1]-benzopyrano[2,3- b]pyridine sodium salt pentahydrate (traxanox sodium, Y-12141) has been shown to exert uricosuric effect in animal experiments. This study was performed to investigate the pharmacokinetics and pharmacological effects of this compound in healthy subjects by double-blind, cross-over comparison with placebo. The urine volume and urinary electrolytes increased significantly after single oral doses of 120 and 360 mg. Urinary excretion of uric acid tended to increase and serum uric acid decreased significantly. Traxanox sodium did not induce any significant change in blood pressure and pulse rate. These results suggest that traxanox sodium is a useful diuretic agent with uricosuric effect.

(Acylaryloxy)acetic acid diuretics. 5. [(2-Alkyl- and 2,2-disubstituted-1,3-dioxo-5-indanyl)oxy]acetic acids

Investigation of the chemistry of the potent uricosuric diuretic indacrinone (MK-196) prompted the synthesis of a series of 3-oxo derivatives, i.e., the indan-1,3-diones. In general, both pharmacological parameters (uricosuria and diuresis) were significantly less pronounced with the 1,3-diones than with the parent 1-oxo compounds.

The physiological disposition of the uricosuric-saluretic agent (6,7-dichloro-2-methyl-1-oxo-2-phenyl-5-indanyloxy)acetic acid (MK-196) in the rat, dog, and monkey

The physiological disposition of a new saluretic-uricosuric agent, (6,7-dichloro-2-methyl-1-oxo-2-phenyl-5-indanyloxy)acetic acid (MK-196), was studied in the rat, dog, and monkey. MK-196 was well absorbed and showed minimal metabolism in these species. Peak plasma levels of radioactivity and drug occurred 0.5-2 hr after oral administration at a dose of 2.5 mg/kg. Essentially all of the radioactivity present in the plasma during the first day was intact MK-196. Following a single dose, a long terminal half-life for plasma radioactivity was observed in the dog (approximately 68 hr) and monkey (approximately 105 hr). The chronic administration of MK-196 to dogs resulted in a dose-related plasma profile and showed no tendency to increase or decrease with dosing. However, upon repeated drug administration to monkeys, the plasma levels of drug increased and then decreased, possibly due to hypochloremia and secondary metabolic alkalosis. Fecal excretion was the predominant route of tracer elimination in the dog (approximately 80%) and rat (approximately 94%), whereas the monkey eliminated the majority of the dose (approximately 60%) via the urine. Minimal metabolism was noted in the three lower species; most of the urinary, plasma, and fecal radioactivity was accounted for as intact drug and its glucuronide conjugate. Three minor metabolites, which were present in dog bile, plasma, and urine, were characterized as: (l,7-dichloro-1alpha-hydroxy-2-methyl-2-phenyl-5-indanyloxy)acetic acid, I; (6,7-dichloro-2-(4-hydroxyphenyl)-2-methyl-2-oxo-5-indanyloxy)acetic acid, II; and 2-methyl-2-phenyl-5-hydroxy-6,7-dichloro-1-indanone, III. The monkey urine and plasma also contained small amounts of II.

Veterans Administration Cooperative Study Group on Antihypertensive Agents. Comparative effects of ticrynafen and hydrochlorothiazide in the treatment of hypertension

Two dose levels of ticrynafen, a new uricosuric diuretic, and of hydrochlorothiazide were randomly assigned, double-blind to 240 men with initial diastolic blood pressures in the range of 95 to 114 mm Hg. A dose of 500 mg of ticrynafen once daily exerted an antihypertensive effect comparable to that of 50 or 100 mg of hydrochlorothiazide. Whereas serum uric acid levels rose in patients treated with hydrochlorothiazide, they fell markedly in those receiving ticrynafen. Otherwise, both diuretics produced similar chemical changes in serum. Patients tolerated ticrynafen as well as they did hydrochlorothiazide over a period of six months of observation, and there was no evidence of serious toxicity or loss of therapeutic effect with ticrynafen. This antihypertensive agent, in appropriate doses, appears to be as effective and well tolerated as hydrochlorothiazide, and in addition ticrynafen prevents hyperuricemia.

[Interactions of drugs, used in the treatment of rheumatism in the elderly (author's transl)]

This paper reviews the possibilities of interactions of drugs, used in the treatment of rheumatism in the elderly. Exspecially glycosides, antikoagulants, diuretics, uricosurics, salicylates, barbiturates and corticosteroides are discussed.

(Acylaryloxy)acetic acid diuretics. 1. (2-Alkyl- and 2,2-dialkyl-1-oxo-5-indanyloxy)acetic acids

The discovery of the (acryloylaryloxy)acetic acids as a new class of potent diuretics prompted the investigation of related bicyclic compounds. Annelated analogues of the parent series, the (2-alkyl- and 2,2-dialkyl-1-oxo-5-indanyloxy)acetic acids, were the subjects of this study. Those compounds, unlike the monocyclic parent compound, lacked the double bond adjacent to the carbonyl group. More importantly, they possessed both saluretic and uricosuric properties. The optimal single 2-substituents for maximal saluretic and uricosuric activity were determined. In general, better activity was observed when a second 2-alkyl substituent (especially methyl) was present in the molecule. Replacement of the carboxy substituent by 5-tetrazolyl generally resulted in a reduction in activity.