Anti-aldosteronergic effect of torasemide

Loop diuretics inhibit kynurenic acid production and kynurenine aminotransferases activity in rat kidneys

BACKGROUND

Loop diuretics became a cornerstone in the therapy of hypervolemia in patients with chronic kidney disease or heart failure. Apart from the influence on water and electrolyte balance, these drugs were shown to inhibit tissue fibrosis and renin-angiotensin-system activity. The kynurenine (KYN) pathway products are suggested to be uremic toxins. Kynurenic acid (KYNA) is synthesized by kynurenine aminotransferases (KATs) in the brain and periphery. The cardiovascular and renal effects of KYNA are well documented. However, high KYNA levels have been correlated with the rate of kidney damage and its complications. Our study aimed to assess the effect of loop diuretics, ethacrynic acid, furosemide, and torasemide on KYNA synthesis and KATs activity in rat kidneys in vitro.

METHODS

Quantitative analyses of KYNA were performed using fluorimetric HPLC detection. Additionally, molecular docking studies determined the possible interactions of investigated compounds with an active site of KAT I and KAT II.

RESULTS

All studied drugs inhibited KYNA production in rat kidneys in vitro at 0.5-1.0 mmol/l concentrations. Only ethacrynic acid at 1.0 mmol/l concentration significantly lowered KAT I and KAT II activity in kidney homogenates, whereas other drugs were ineffective. Molecular docking results indicated the common binding site for each of the studied loop diuretics and KYNA. They suggested possible residues involved in their binding to the active site of both KAT I and KAT II model.

CONCLUSIONS

Our study reveals that loop diuretics may decrease KYNA synthesis in rat kidneys in vitro. The presented results warrant further research in the context of KYN pathway activity regulation by loop diuretics.

Effect of Goreisan, a Traditional Japanese Medicine, on Rat Hindlimb Lymphedema

Secondary lymphedema occurs after cancer surgery involving lymph node dissection owing to the lymphatic system dysfunction. However, the pathophysiology of lymphedema and the molecular pathways involved remain unknown. This study aimed to develop a rat hindlimb lymphedema model and investigate the mechanisms that drive pathophysiology and the effects of the traditional Japanese medicine goreisan on lymphedema. The rat lymphedema model was induced by combination surgeries of popliteal lymph node dissection, skin cautery incision, and fascial ablation coagulation in the right hindlimb using male Wistar rats. The foot volume was significantly increased, and recovery was delayed by combination surgeries. Dermal thickness and dilated lymphatic vessels of the hindlimb were observed on postoperative day 2. The number of infiltrating leukocytes (CD45+ cells), including CD4+ T-cells, increased in the lymphedema group compared with that in the sham group. The relative mRNA expression and protein levels of interleukin-6 (IL-6), CC chemokine ligand 2 (CCL2), transforming growth factor β1 (TGF-β1), and Fms-related receptor tyrosine kinase 4 (FLT4) were significantly higher in the lymphedema group than in the sham group. Foot volume was decreased by goreisan, furosemide, and prednisolone treatments. Goreisan diminished the increase in CD4+ T-cells, and the same trend was observed for CCL2 and FLT4 expression. In conclusion, the rat hindlimb lymphedema model in this study exhibited increased foot volume, skin-infiltrating cells, and pathological changes accompanied by inflammatory and fibrotic responses, suggesting that the model presented significant clinical features of lymphedema. Goreisan may exert a therapeutic effect on lymphedema by inhibiting CD4+ T-cell infiltration.

Use of short-acting vs. long-acting loop diuretics after heart failure hospitalization

AIMS

Furosemide, a short-acting loop diuretic (SD), is the dominant agent prescribed for heart failure (HF) in clinical practice. However, accumulating data suggests that long-acting loop diuretics (LD), such as torsemide or azosemide, might have more favourable pharmacological profiles. This study aimed to investigate the relationship between the type of loop diuretics and long-term outcomes among patients hospitalized for acute HF enrolled in a contemporary multicentre registry.

METHODS AND RESULTS

Within the West Tokyo Heart Failure Registry from 2006 to 2017, a total of 2680 patients (60.1% men with a median age of 77 years) were analysed. The patients were characterized by the type of diuretics used at the time of discharge; 2073 (77.4%) used SD, and 607 (22.6%) used LD. The primary endpoint was composite of all-cause death or HF re-admission after discharge, and the secondary endpoints were all-cause death and HF re-admission, respectively. During the median follow-up period of 2.1 years, 639 patients died [n = 519 (25.0%) in the SD group; n = 120 (19.8%) in the LD group], and 868 patients were readmitted for HF [n = 697 (33.6%) in the SD group; n = 171 (28.2%) in the LD group]. After multivariable adjustment, the LD group had lower risk for the composite outcome [hazard ratio (HR), 0.80; 95% confidence interval (CI), 0.66-0.96; P = 0.017], including all-cause death (HR; 0.73; 95% CI; 0.54-0.99; P = 0.044) and HF re-admission (HR, 0.81; 95% CI, 0.66-0.99; P = 0.038), than the SD group. Propensity score matching yielded estimates that were consistent with those of the multivariable analyses, with sub-group analyses demonstrating that use of LD was associated with favourable outcomes predominantly in younger patients with reduced ejection fraction.

CONCLUSIONS

LD was associated with lower risk of long-term outcomes in patients with HF and a recent episode of acute decompensation.

Heart failure with preserved ejection fraction: key stumbling blocks for experimental drugs in clinical trials

INTRODUCTION

Heart failure with preserved ejection fraction (HFpEF) is a disease process with a high prevalence. Accounting for more than 50% of all heart failure cases, it carries a significant mortality. So far, there has been a lack of therapeutic options that truly show improvement in morbidity and mortality. Certain novel therapies have shown a decrease in heart failure hospitalizations, however, this beneficial effect was more pronounced for heart failure patients with mildly reduced ejection fraction (EF).

AREAS COVERED

This review summarizes the pathophysiology of the disease to help elucidate the differences between heart failure with reduced ejection fraction (HFrEF), and HFpEF, which could explain why therapies are successful in one (rather than the other). At the focus of this review are non-standardized nomenclature across major trials, the challenges of finding a therapeutic agent for such a heterogeneous population, and identification of specific phenotypes that have different outcomes and could be a target for future therapies.

EXPERT OPINION

Lack of standardized diagnostic criteria, associated with population heterogeneity, might explain why trials have failed to improve outcomes for patients with HFpEF. Standardizing phenotypes and recapitulating these phenotypes in animal models, as well as understanding the mechanisms of the disease at the molecular level could be the first steps in identifying promising therapeutic options.

Proteomic differences among patients with heart failure taking furosemide or torsemide

BACKGROUND

Loop diuretics are commonly used for patients with heart failure (HF) but it remains unknown if one loop diuretic is clinically superior.

HYPOTHESIS

Biomarkers and proteomics provide insight to how different loop diuretics may differentially affect outcomes.

METHODS

Blood and urine were collected from outpatients with HF who were taking torsemide or furosemide for >30 days. Differences were assessed in cardiac, renal, and inflammatory biomarkers and soluble protein panels using the Olink Cardiovascular III and inflammation panels.

RESULTS

Of 78 subjects, 55 (71%) were treated with furosemide and 23 (29%) with torsemide, and 25 provided a urine sample (15 treated with furosemide, 10 with torsemide). Patients taking torsemide were older (68 vs 64 years) with a lower mean eGFR (46 vs 54 ml/min/1.73 m² ), a higher proportion were women (39% vs 24%) and Black (43% vs 27%). In plasma, levels of hs-cTnT, NT-proBNP, and hsCRP were not significantly different between groups. In urine, there were significant differences in urinary albumin, β-2M, and NGAL, with higher levels in the torsemide-treated patients. Of 184 proteins testing in Olink panels, in plasma, 156 (85%) were higher in patients taking torsemide but none were significantly different after correcting for false discovery.

CONCLUSIONS

We show differences in urinary biomarkers but few differences in plasma biomarkers among HF patients on different loop diuretics. Olink technology can detect differences in plasma protein levels from multiple biologic domains. These findings raise the importance of defining differences in mechanisms of action of each diuretic in an appropriately powered study.

An evaluation of torsemide in patients with heart failure and renal disease

INTRODUCTION

Torsemide is a loop diuretic that inhibits the Na+/K+/2Cl- cotransporter type 2 in the thick ascending loop of Henle, leading to increased excretion of urinary sodium and chloride and associated diuresis. While furosemide remains the dominant diuretic utilized in current practice, increasing evidence supports potential advantages of torsemide in heart failure (HF) and/or renal disease.

AREAS COVERED

This narrative review covers the evidence for use of torsemide in HF and renal disease. Comparative effectiveness with regards to clinical outcomes is reviewed, as well as the ongoing multicenter trial, TRANSFORM-HF, comparing the effect of torsemide versus furosemide among patients with HF.

EXPERT OPINION

Compared with furosemide, torsemide has favorable pharmacodynamics/pharmacokinetics including higher bioavailability, longer duration of effect, minor renal excretion, decreased kaliuresis, and enhanced natriuresis/diuresis. These properties may be further supported by differential effects on RAAS regulation and fibrosis modulation as compared with other diuretics. The limited current body of evidence indicates that torsemide may be superior to furosemide with respect to improving HF functional status and reducing HF hospitalization, and there are mixed data regarding effect on reducing overall cardiovascular hospitalizations/mortality. Further, randomized data are necessary to definitively determine if torsemide can reduce risk of mortality and hospitalization among patients with HF.

Safety of torasemide in healthy adult dogs administered daily for 26 weeks

Thirty‐two (16 males and 16 females) healthy young beagles were randomly divided into four groups of eight. The control group remained untreated. Torasemide (ISEMID^®, Ceva Santé Animale) was orally administered, once daily, at 0.5 mg/kg from Days 1–5 then 0.25 mg/kg to Day 182, and at three times and five times this dosing regimen in two additional groups. Treated animals (predominantly at the higher dose levels) showed dryness of the oral mucosa, evidence of diuresis, decreased diet consumption, decreased bodyweight gain over the first 3 weeks, increased water consumption, increases in erythrocytes count, haemoglobin, calcium and magnesium, decrease in chloride, phosphorus, potassium and sodium, increases in urine pH, decreases in urine specific gravity and increases in serum aldosterone concentrations. Plasma concentrations of torasemide increased in a dose‐dependent manner and showed no evidence of accumulation. There were also changes to electrocardiogram patterns and the macroscopic and microscopic appearance of the kidney and adrenal glands, but these changes were almost exclusively confined to the over‐dosed groups. In conclusion, torasemide was found to be safe when administered to dogs at 0.25 mg/kg once daily for 26 weeks, and any changes were consistent with its known diuretic effects.

READY: relative efficacy of loop diuretics in patients with chronic systolic heart failure-a systematic review and network meta-analysis of randomised trials

The majority of patients with chronic heart failure (HF) receive long-term treatment with loop diuretics. The comparative effectiveness of different loop diuretics is unknown. We searched PubMed, clinicaltrials.gov , the Cochrane Central Register of Controlled Trials and the European Union Clinical Trials Register for randomised clinical trials exploring the efficacy of the loop diuretics azosemide, bumetanide, furosemide or torasemide in patients with HF. Comparators included placebo, standard medical care or any other active treatment. The primary endpoint was all-cause mortality. Secondary endpoints included cardiovascular mortality, HF-related hospitalisation and any combined endpoint thereof. Hypokalaemia and acute renal failure were defined as additional safety endpoints. Evidence was synthesised using network meta-analysis (NMA). Thirty-four trials reporting on 2647 patients were included. The overall quality of evidence was rated as moderate. NMA demonstrated no significant differences between loop diuretics with respect to all-cause mortality, cardiovascular mortality or hypokalaemia. In contrast, torasemide ranked best in terms of HF hospitalisation, and there was a trend towards benefits with torasemide with regard to occurrence of acute renal failure. Sensitivity analyses excluding trials with a follow-up < 6 months, trials with a cross-over design and those including < 25 patients confirmed the main results. We found no significant superiority of either loop diuretic with respect to mortality and safety endpoints. However, clinicians may prefer torasemide, as it was associated with fewer HF-related hospitalisations.

Comparative effectiveness of torasemide versus furosemide in symptomatic therapy in heart failure patients: Preliminary results from the randomized TORNADO trial

BACKGROUND

Recent reports suggest that torasemide might be more beneficial than furosemide in patients with symptomatic heart failure (HF). The aim was to compare the effects of torasemide and furosemide on clinical outcomes in HF patients.

METHODS

This study pilot consisted of data from the ongoing multicenter, randomized, unblinded endpoint phase IV TORNADO (NCT01942109) study. HF patients in New York Heart Association (NYHA) II-IV class with a stable dose of furosemide were randomized to treatment with equipotential dose of torasemide (4:1) or continuation of unchanged dose of furosemide. On enrollment and control visit (3 months after enrollment) clinical examination, 6-minute walk test (6MWT) and assessment of fluid retention by ZOE Fluid Status Monitor were performed. The primary endpoint was a composite of improvement of NYHA class, improvement of at least 50 m during 6MWT and decrease in fluid retention of at least 0.5 W after 3-months follow-up.

RESULTS

The study group included 40 patients (median age 66 years; 77.5% male). During follow-up 7 patients were hospitalized for HF worsening (3 in torasemide and 4 in furosemide-treated patients). The primary endpoint reached 15 (94%) and 14 (58%) patients on torasemide and furosemide, respectively (p = 0.03).

CONCLUSIONS

In HF patients treated with torasemide fluid overload and symptoms improved more than in the furosemide group. This positive effect occurred already within 3-month observation.

Comparison between the effects of torsemide and furosemide on the renin-angiotensin-aldosterone system of normal dogs

INTRODUCTION/OBJECTIVES

We hypothesized that torsemide and furosemide, at approximately equipotent dosages (similar diuresis), would have comparable effects on the circulating renin-angiotensin-aldosterone system.

ANIMALS, MATERIALS AND METHODS

Six, healthy, middle-aged, male Beagles were randomized to receive torsemide (0.1 mg/kg PO q 12 h), furosemide (2.0 mg/kg PO q 12 h), or placebo for 10 days during three separate periods, separated by a 10-day washout period, in a crossover design. Blood was collected on days 1, 5, and 9 and 24-h urine collection ended on days 2, 6, and 10. After repeated measures analysis and Bonferonni correction, variables with an adjusted p<0.05 were investigated further, using Tukey's method.

RESULTS

Twenty-four-hour urine production differed significantly between the diuretics only on day 10, with torsemide causing a 38% greater diuresis than furosemide. There was, however, no significant difference in average 3-day diuresis. There were no significant differences between diuretics in the 24-h urinary excretion of sodium, chloride, or potassium, though furosemide caused less kaliuresis than torsemide. Serum renin, angiotensin II, and aldosterone and the urine aldosterone-to-creatinine ratio were significantly increased in the diuretic groups, as compared to placebo on days 5/6 and 9/10. There were no significant differences in these values between diuretics. Creatinine and blood urea nitrogen concentrations rose comparably in the diuretic groups, remaining within reference intervals in all dogs.

CONCLUSIONS

At approximately equipotent dosages (20:1), torsemide and furosemide produced comparable renin-angiotensin-aldosterone system activation. Torsemide's similar potassium excretion profile to furosemide decreases support for a hypothesized mineralocorticoid-receptor blocking capability.

Drug Targets for Heart Failure with Preserved Ejection Fraction: A Mechanistic Approach and Review of Contemporary Clinical Trials

Heart failure with preserved ejection fraction (HFpEF) accounts for over half of prevalent heart failure (HF) worldwide, and prognosis after hospitalization for HFpEF remains poor. Due, at least in part, to the heterogeneous nature of HFpEF, drug development has proved immensely challenging. Currently, there are no universally accepted therapies that alter the clinical course of HFpEF. Despite these challenges, important mechanistic understandings of the disease have revealed that the pathophysiology of HFpEF is distinct from that of HF with reduced ejection fraction and have also highlighted potential new therapeutic targets for HFpEF. Of note, HFpEF is a systemic syndrome affecting multiple organ systems. Depending on the organ systems involved, certain novel therapies offer promise in reducing the morbidity of the HFpEF syndrome. In this review, we aim to discuss novel pharmacotherapies for HFpEF based on its unique pathophysiology and identify key research strategies to further elucidate mechanistic pathways to develop novel therapeutics in the future.

Pharmacokinetic and pharmacodynamic properties of orally administered torsemide in healthy horses

BACKGROUND

Diuretic treatment is the mainstay for management of congestive heart failure in horses, and its use has been restricted to injectable medications because no currently data supports the use of PO administered loop diuretics.

OBJECTIVES

To determine the pharmacokinetic and pharmacodynamic properties of PO administered torsemide and, determine if PO administered torsemide, could be used as an alternative to injectable diuretics in the horse.

ANIMALS

Six healthy adult mares.

METHODS

A 2-phase, prospective study, that consisted of pharmacokinetic profiling of a single dose (6 mg/kg PO) and pharmacodynamic effects of long-term torsemide administration (2 mg/kg PO q12h) for 6 days in healthy horses.

RESULTS

Pharmacokinetic analysis identified a peak concentration (C_max ) of 10.14 µg/mL (range, 6.79-14.69 µg/mL) and elimination half-life (T_1/2 ) 9.2 hours (range, 8.4-10.4 hours). The area under the plasma drug concentration over time curve (AUC) was 80.7 µg × h/mL (range, 56.5-117.2 µg × h/mL). A statistically significant increase in urine volume and decrease in urine specific gravity were found from day 0 (baseline) to day 6 (P < .0001). Significant alterations in biochemical variables included hyponatremia, hypokalemia, hypochloremia, and increased serum creatinine concentration. Mean arterial blood pressure significantly decreased on day 6 (57.7 ± 8.8 mm Hg, P = .001) as compared with baseline (78 ± 6.1 mm Hg). Serum aldosterone concentrations significantly increased after 6 days of torsemide administration (P = .0006).

CONCLUSIONS AND CLINICAL IMPORTANCE

PO administered torsemide (4 mg/kg/day) successfully reached therapeutic concentrations in blood, induced clinically relevant diuresis, and resulted in moderate pre-renal azotemia and electrolyte disturbances.

Diuretic Strategies in Acute Decompensated Heart Failure

PURPOSE OF REVIEW

The burden of heart failure in the United States is growing rapidly to epic proportions with serious clinical implications for patients and economic strain for healthcare systems. One of the most common reasons for hospitalization in acute decompensated heart failure (ADHF) is excess volume accumulation which leads to untoward symptoms including dyspnea,orthopnea, and edema.

RECENT FINDINGS

Over the past several decades, there has been great interest in exploring various decongestive strategies in order to achieve symptomatic improvement and favorable clinical outcomes. These include different modalities of loop diuretic administration, the adjunctive use of non-loop diuretics, and other diuretic sparing strategies. Herein, we provide an appraisal of these decongestive strategies and discuss novel concepts predicting clinical outcomes based on diuretic response and decongestive adequacy while discussing commonly encountered problems such as worsening renal function in ADHF.

Short-Term Efficacy and Safety of Torasemide and Furosemide in 366 Dogs with Degenerative Mitral Valve Disease: The TEST Study

BACKGROUND

Furosemide is the only loop diuretic recommended by the ACVIM consensus guidelines for treatment of congestive heart failure (CHF) in dogs related to degenerative mitral valve disease (DMVD). Torasemide is another potent loop diuretic with a longer half-life and a higher bioavailability.

OBJECTIVES

(1) To demonstrate that torasemide given once a day (q24h) is noninferior to furosemide given twice a day (q12h) for treating dogs with CHF; (2) and to compare the effect of the 2 drugs on the time to reach a composite cardiac endpoint "spontaneous cardiac death, euthanasia due to heart failure or CHF class worsening."

ANIMALS

A total of 366 dogs with CHF attributable to DMVD.

METHODS

Analysis of 2 prospective randomized single-blinded reference-controlled trials was performed. Dogs orally received either torasemide q24h (n = 180) or furosemide q12h (n = 186) in addition to standard CHF therapy over 3 months. The primary efficacy criterion was the percentage of dogs with treatment success assessed in each study. The time to reach the composite cardiac endpoint was used as secondary criterion in the overall population.

RESULTS

Torasemide was noninferior to furosemide (Ptorasemide  - Pfurosemide  = +7%; 95% CI [-8%; +22%] and Ptorasemide  - Pfurosemide  = +1%; 95% CI [-12%; +14%], respectively, in Study 1 and Study 2). Torasemide (median dose = 0.24 mg/kg/d q24h; range = 0.10-0.69 mg/kg/d) was associated with a 2-fold reduction in the risk of reaching the composite cardiac endpoint (adjusted HR = 0.47; 95% CI = 0.27-0.82; P = 0.0077) as compared with furosemide (median dose = 1.39 mg/kg q12h; range = 0.70-6.30 mg/kg q12h).

CONCLUSIONS AND CLINICAL IMPORTANCE

Torasemide q24h is an effective oral diuretic in dogs with CHF.

[Use of loop diuretics in heart failure: Current aspects]

Loop diuretics take the lead in the treatment of patients with symptomatic heart failure. Torasemide is the most effective and safe loop diuretic with the optimal pharmacokinetic profile, the additional properties associated with simultaneous blockade of the renin-angiotensin-aldosterone system and with the antiadrenergic effects of the drug, its positive impact on myocardial fibrosis and minimal severe potential negative effects. Sustained-release torasemide provides a more comfortable removal of excess liquid and does not deteriorate quality of life.

The impact of torasemide on haemodynamic and neurohormonal stress, and cardiac remodelling in heart failure - TORNADO: a study protocol for a randomized controlled trial

BACKGROUND

Approximately 50% of heart failure patients are readmitted to hospital within 6 months, owing to deterioration of their condition. Thus, symptomatic treatment of heart failure requires significant improvement. The aim of this study is to compare the effects of torasemide and furosemide on biochemical parameters of haemodynamic and neurohormonal compensation, myocardial remodelling, clinical outcomes and quality of life in patients with chronic heart failure.

METHODS

This is a multicentre, randomized, open, blinded endpoint phase-IV trial. The study includes 120 heart failure patients in NYHA (New York Heart Association) functional class II-IV, treated with optimal heart failure therapy, with indications for use of loop diuretics. At enrolment, patients are stable, with a fixed dose of loop diuretics. Patients are randomized to treatment with furosemide or torasemide (randomization 1:1). After randomization, the current fixed dose of furosemide is continued or is replaced by an equipotential dose of torasemide (4:1). The study consists of two control visits (3 and 6 months after enrolment) with minimal follow-up of 6 months. Assessment involves clinical examination, Quality of Life Questionnaire, laboratory tests, echocardiography, electrocardiography, 24 h Holter-electrocardiography monitoring, 6 -min walk test and assessment of fluid retention. Any need for dose adjustment is assessed during the observation. The primary objective is to compare the effects of torasemide and furosemide on clinical and biochemical parameters of haemodynamic and neurohormonal compensation and myocardial remodelling. Secondary objectives include monitoring of: changes in signs and symptoms of heart failure, NYHA functional class, quality of life, dosage changes, rate of readmissions and mortality.

DISCUSSION

Despite decades of the diuretic's history, knowledge about diuretic therapy is still unsatisfactory. The most widely used diuretic, furosemide, has a stormy pharmacokinetics and pharmacodynamics, and is associated with a high risk of mortality and hospitalization for worsening heart failure. Reports are very encouraging and suggest beneficial effects of torasemide. Hence, there is a need for further studies of the overall effect of torasemide, compared with furosemide. This can translate into improved quality of life and better prognosis of patients with heart failure.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01942109 . Registered on 24 August 2013.

Loop Diuretics in the Treatment of Hypertension

Loop diuretics are not recommended in current hypertension guidelines largely due to the lack of outcome data. Nevertheless, they have been shown to lower blood pressure and to offer potential advantages over thiazide-type diuretics. Torsemide offers advantages of longer duration of action and once daily dosing (vs. furosemide and bumetanide) and more reliable bioavailability (vs. furosemide). Studies show that the previously employed high doses of thiazide-type diuretics lower BP more than furosemide. Loop diuretics appear to have a preferable side effect profile (less hyponatremia, hypokalemia, and possibly less glucose intolerance). Studies comparing efficacy and side effect profiles of loop diuretics with the lower, currently widely prescribed, thiazide doses are needed. Research is needed to fill gaps in knowledge and common misconceptions about loop diuretic use in hypertension and to determine their rightful place in the antihypertensive arsenal.

Torsemide versus furosemide in heart failure patients: insights from Duke University Hospital

Furosemide has historically been the primary loop diuretic in heart failure patients despite data suggesting potential advantages with torsemide. We used the Duke Echocardiography Lab Database to investigate patients admitted with heart failure to Duke Hospital from 2000 to 2010 who were discharged on either torsemide or furosemide. We described baseline characteristics based on discharge diuretic and assessed the relationship with all-cause mortality through 5 years. Of 4580 patients, 86% (n = 3955) received furosemide and 14% (n = 625) received torsemide. Patients receiving torsemide were more likely to be female and had more comorbidities compared with furosemide-treated patients. Survival was worse in torsemide-treated patients [5-year Kaplan-Meier estimated survival of 41.4% (95% CI: 36.7-46.0) vs. 51.5% (95% CI: 49.8-53.1)]. After risk adjustment, torsemide use was no longer associated with increased mortality (hazard ratio 1.16; 95% CI: 0.98-1.38; P = 0.0864). Prospective trials are needed to investigate the effect of torsemide versus furosemide because of the potential for residual confounding.

Torsemide Versus Furosemide in Patients With Acute Heart Failure (from the ASCEND-HF Trial)

Furosemide is the most commonly used loop diuretic in patients with heart failure (HF) despite data suggesting potential pharmacologic and antifibrotic benefits with torsemide. We investigated patients with HF in Acute Study of Clinical Effectiveness of Nesiritide in Decompensated Heart Failure who were discharged on either torsemide or furosemide. Using inverse probability weighting to account for the nonrandom selection of diuretic, we assessed the relation between choice of diuretic at discharge with 30-day mortality or HF hospitalization and 180-day mortality. Of 7,141 patients in the trial, 4,177 patients were included in this analysis, of which 87% (n = 3,620) received furosemide and 13% (n = 557) received torsemide. Torsemide-treated patients had lower ejection fraction and blood pressure and higher creatinine and natriuretic peptide level compared with furosemide. Torsemide was associated with similar outcomes on unadjusted analysis and nominally lower events on adjusted analysis (30-day mortality/HF hospitalization odds ratio 0.89, 95% CI 0.62 to 1.29, p = 0.55 and 180-day mortality hazard ratio 0.86, 95% CI 0.63 to 1.19, p = 0.37). In conclusion, these data are hypothesis-generating and randomized comparative effectiveness trials are needed to investigate the optimal diuretic choice.

Comparative effectiveness of torsemide versus furosemide in heart failure patients: insights from the PROTECT trial

AIM

The authors assessed the comparative effectiveness of torsemide versus furosemide in the PROTECT trial.

METHODS

The authors assessed the relationship between loop diuretic at discharge and death or cardiovascular/renal hospitalization within 30 days, and death through 150 days postdischarge using inverse probability weighting.

RESULTS

Out of 1004 patients, 83.5% received furosemide and 16.5% torsemide. Torsemide patients had higher blood urea nitrogen, and more in-hospital worsening heart failure. Following adjustment, torsemide was associated with similar 30-day outcomes compared with furosemide (p = 0.93), but remained associated with increased 150-day death (hazard ratio: 2.26; 95% CI: 1.40-3.66; p < 0.001).

CONCLUSION

Patients treated with torsemide had features of greater disease severity, similar 30-day outcomes but increased 150-day mortality. Prospective randomized trials are needed to investigate the effect of torsemide versus furosemide.

Volume Overload in Heart Failure: An Evidence-Based Review of Strategies for Treatment and Prevention

Acute decompensated heart failure is the leading cause of hospital admission in the United States, with a high risk of readmission within 30 days. Most acute decompensated heart failure admissions are driven by congestive signs and symptoms resulting from fluid and sodium overload. We reviewed the evidence base addressing the management and prevention of fluid overload in heart failure, focusing on recent clinical trials. All the references in this review were obtained through PubMed and had at least 1 of the following key words: heart failure and volume overload, congestion, loop diuretics, thiazide diuretics, aldosterone antagonists, dopamine, cardiorenal syndrome, nesiritide, vasopressin antagonists, ultrafiltration, sodium restriction, fluid restriction, telemonitoring, and invasive hemodynamic monitoring. We also reviewed relevant references cited in the obtained articles, especially articles addressing methods of treating or preventing volume overload in patients with heart failure.

Inhibition of aldosterone synthase (CYP11B2) by torasemide prevents atrial fibrosis and atrial fibrillation in mice

Loop diuretics are used for fluid control in patients with heart failure. Furosemide and torasemide may exert differential effects on myocardial fibrosis. Here, we studied the effects of torasemide and furosemide on atrial fibrosis and remodeling during atrial fibrillation. In primary neonatal cardiac fibroblasts, torasemide (50μM, 24h) but not furosemide (50μM, 24h) reduced the expression of connective tissue growth factor (CTGF; 65±6%) and the pro-fibrotic miR-21 (44±23%), as well as the expression of lysyl oxidase (LOX; 57±8%), a regulator of collagen crosslinking. Mineralocorticoid receptor (MR) expression and activity were not altered. Torasemide but not furosemide inhibited human aldosterone synthase (CYP11B2) activity in transfected lung fibroblasts (V79MZ cells) by 75±1.8%. The selective CYP11B2 inhibitor SL242 mimicked the torasemide effects. Mice with cardiac overexpression of Rac1 GTPase (RacET), which develop atrial fibrosis and spontaneous AF with aging, were treated long-term (8months) with torasemide (10mg/kg/day), furosemide (40mg/kg/day) or vehicle. Treatment with torasemide but not furosemide prevented atrial fibrosis in RacET as well as the up-regulation of CTGF, LOX, and miR-2, whereas MR expression and activity remained unaffected. These effects correlated with a reduced prevalence of atrial fibrillation (33% RacET+Tora vs. 80% RacET). Torasemide but not furosemide inhibits CYP11B2 activity and reduces the expression of CTGF, LOX, and miR-21. These effects are associated with prevention of atrial fibrosis and a reduced prevalence of atrial fibrillation in mice.

A reappraisal of loop diuretic choice in heart failure patients

The health and economic burden of heart failure is significant and continues to grow each year. Loop diuretics are an integral part of symptom management in heart failure. Furosemide is used disproportionately compared with other loop diuretics, and there is currently no guidance for physicians regarding which agent to choose. However, there exist pharmacologic differences as well as other mechanistic differences that appear to favor torsemide use over furosemide. Compared with furosemide, torsemide improves surrogate markers of heart failure severity such as left ventricular function, plasma brain natriuretic peptide levels, and New York Heart Association functional class and may also reduce hospitalizations, readmissions, and mortality. Data suggest that these benefits could be mediated through torsemide's ability to positively affect the renin-angiotensin-aldosterone system. Specifically, torsemide has been shown to inhibit aldosterone secretion, synthesis, and receptor binding in vitro, as well as decrease transcardiac extraction of aldosterone, myocardial collagen production, and cardiac fibrosis in patients with heart failure. We identified pertinent literature using keyword MEDLINE searches and cross-referencing prior bibliographies. We summarize the available data suggesting potential benefits with torsemide over furosemide, and call attention to the need for a reappraisal of diuretic use in heart failure patients and also for a well-powered, randomized control trial assessing torsemide versus furosemide use.

Impact of mineralocorticoid receptor polymorphisms on urinary electrolyte excretion with and without diuretic drugs

Aim: Polymorphisms in the mineralocorticoid receptor may affect urinary sodium and potassium excretion. We investigated polymorphisms in the MR gene in relation to urinary electrolyte excretion in two separate studies. Patients & methods: The genotype–phenotype association was studied in healthy volunteers after single doses of bumetanide, furosemide, torsemide, hydrochlorothiazide, triamterene and after NaCl restriction. Results: High potassium excretion under all conditions except torsemide, and high NaCl excretion after bumetanide and furosemide were associated with the A allele of the intron-3 polymorphism (rs3857080). This polymorphism explained 5–10% of the functional variation and in vitro, rs3857080 affected DNA binding of the transcription factor LHX4. Conclusion: rs3857080 may be a promising new candidate for research in cardiac and renal disorders and on antialdosteronergic drugs like spironolactone.

Original submitted 23 June 2014; Revision submitted 5 November 2014

New insights into combinational drug therapy to manage congestion in heart failure

Congestion is the most important contributor to morbidity and mortality in heart failure. In patients without congestion, maintaining a neutral sodium balance is imperative to prevent evolving volume overload. Adequate use of neurohumoral blockers, in combination with dietary sodium restriction, is essential and may preclude the need for maintenance diuretic therapy. If volume overload still prevails, loop diuretics remain the mainstay treatment to reduce excessive extracellular volume. However, combinational drug therapy might offer a more attractive alternative to achieve a balanced natriuresis, instead of further uptitration of loop diuretics. Importantly, elevated cardiac filling pressures may be caused by volume misdistribution and impaired venous capacitance, rather than absolute volume overload. Vasodilator therapy to unload the heart, increase venous capacitance, and lower arterial impedance might be interesting in such cases. This review offers a practical approach into current and potential future pharmacologic therapies for managing congestion, focusing on combinational and targeted therapy.

The diuretic torasemide does not prevent aldosterone-mediated mineralocorticoid receptor activation in cardiomyocytes

Aldosterone binds to the mineralocorticoid receptor (MR) and exerts pleiotropic effects beyond enhancing renal sodium reabsorption. Excessive mineralocorticoid signaling is deleterious during the evolution of cardiac failure, as evidenced by the benefits provided by adding MR antagonists (MRA) to standard care in humans. In animal models of cardiovascular diseases, MRA reduce cardiac fibrosis. Interestingly diuretics such as torasemide also appear efficient to improve cardiovascular morbidity and mortality, through several mechanisms. Among them, it has been suggested that torasemide could block aldosterone binding to the MR. To evaluate whether torasemide acts as a MRA in cardiomyocytes, we compared its effects with a classic MRA such as spironolactone. We monitored ligand-induced nuclear translocation of MR-GFP and MR transactivation activity in the cardiac-like cell line H9C2 using a reporter gene assay and known endogenous aldosterone-regulated cardiac genes. Torasemide did not modify MR nuclear translocation. Aldosterone-induced MR transactivation activity was reduced by the MRA spironolactone, not by torasemide. Spironolactone blocked the induction by aldosterone of endogenous MR-responsive genes (Sgk-1, PAI-1, Orosomucoid-1, Rgs-2, Serpina-3, Tenascin-X), while torasemide was ineffective. These results show that torasemide is not an MR antagonist; its association with MRA in heart failure may however be beneficial, through actions on complementary pathways.

Should torsemide be the loop diuretic of choice in systolic heart failure?

Furosemide is the most widely prescribed loop diuretic in the setting of systolic heart failure (HF), yet torsemide has been shown to have less inter- and intra-individual variation in bioavailability and a longer duration of action compared with furosemide. Thus, a systematic review and meta-analysis of randomized controlled trials comparing torsemide versus furosemide in patients with systolic HF using OVID MEDLINE, Excerpta Medica (Embase), Web of Science, PubMed and Google Scholar was performed. Extracted data included study design, sample characteristics, intervention, outcomes and control for potential confounding factors. A DerSimonian and Laird random-effects model was used to compute summary risk ratios for HF and cardiovascular (CV) readmission outcomes. Two randomized trials comparing furosemide with torsemide in 471 patients with systolic HF were identified. Compared to furosemide, torsemide significantly reduced total HF readmissions (relative risk [RR]: 0.41, 95% CI: 0.28–0.61, p < 0.0001) and HF readmissions (RR: 0.53, 95% CI: 0.33–0.84, p = 0.008) as well as CV readmissions (RR: 0.77, 95% CI: 0.60–0.98, p = 0.03) in patients with “at least 1 readmission.” Moreover, compared with furosemide, torsemide caused a 14% reduction in all-cause mortality (RR: 0.86 [0.53–1.39], p = 0.54). Compared with furosemide, torsemide significantly reduces HF and CV-related hospital readmissions in systolic HF. Furthermore, torsemide is associated with a trend in reducing all-cause mortality.

Pharmacologic management of myxomatous mitral valve disease in dogs

Myxomatous mitral valve disease (MMVD) causing mitral regurgitation is the most important disease of the heart in small animal cardiovascular medicine. Because MMVD is an example of a chronic disease that progresses from mild to severe over years, treatment strategies change with the stage of the disease. In this review the treatment options are compared and contrasted as they are discussed relative to the recently published ACVIM consensus statement regarding the treatment of MMVD. Results from clinical trials and evidence-based medicine are likely to provide significant improvements in the management of MMVD in the coming decades.

Effect of torsemide and furosemide on clinical, laboratory, radiographic and quality of life variables in dogs with heart failure secondary to mitral valve disease

OBJECTIVES

Diuretic therapy reduces preload and relieves congestion secondary to cardiac dysfunction. Torsemide (torasemide) is a loop diuretic with longer duration of action, decreased susceptibility to diuretic resistance, and adjunctive aldosterone antagonist properties compared with furosemide. We hypothesized that torsemide would be well tolerated and no less effective than furosemide at diuresis, control of clinical signs, and maintenance of quality of life (QOL) in dogs with congestive heart failure (CHF).

ANIMALS, MATERIALS AND METHODS

Seven client-owned dogs with stable CHF receiving twice daily oral furosemide and adjunctive medications. Utilizing a double-blinded, randomized, crossover design, dogs were administered either oral furosemide at their current dose or an equivalent oral dose of torsemide (1/10 of the daily furosemide dose divided into twice daily dosing) on day 0. Crossover occurred at day 7 and the study ended on day 14. Clinical, laboratory, radiographic, and QOL variables were evaluated on days 0, 7 and 14.

RESULTS

No dogs developed recurrent CHF during the study. Mean furosemide dose on day 0 was 5.13 mg/kg/day (range 2.8-9.6). Following torsemide treatment, creatinine (P = 0.020), urea nitrogen (P = 0.013), phosphorus (P = 0.032), albumin (P = 0.019), carbon dioxide (P = 0.015) and anion gap (P = 0.005) were significantly increased, and urine specific gravity (P = 0.004) and chloride (P = 0.021) were significantly decreased compared with furosemide dosing. No differences in QOL were found.

CONCLUSIONS

Results indicate that torsemide is equivalent to furosemide at controlling clinical signs of CHF in dogs and is likely to achieve greater diuresis vs. furosemide. Larger clinical trials evaluating torsemide as a first or second-line loop diuretic for congestive heart failure in dogs are warranted.

Use of the loop diuretic torsemide in three dogs with advanced heart failure

Diuretics are a mainstay of therapy in dogs with heart failure. In dogs with advanced heart failure, moderate to high doses of loop diuretics such as furosemide are used with diminishing effects as profound activation of neuroendocrine systems promote signs of congestive heart failure. The loop diuretic torsemide has several characteristics that make it suitable for treatment of advanced heart failure including longer half-life, increased potency of diuretic action, and anti-aldosterone effects. This case report details the administration of torsemide in 3 dogs with advanced heart failure and apparent furosemide resistance.

Management of loop diuretic resistance in the intensive care unit

PURPOSE

The management of loop diuretic resistance in the intensive care unit (ICU) is reviewed.

SUMMARY

Volume overload, a common complication of fluid resuscitation, is frequently encountered in the ICU and is associated with numerous adverse effects, including pulmonary and peripheral edema, acute lung injury, and pleural effusions. Loop diuretics are used to treat volume overload and acute renal failure and to ameliorate their associated complications. When administered intravenously, these drugs induce vigorous and prompt diuresis, which may result in negative fluid balance. This may also result in significant adverse effects, including electrolyte imbalance, ototoxicity, and volume contraction. Prolonged use of loop diuretics may lead to loop diuretic resistance, a frequent observation in the ICU. Three general mechanisms are used to explain loop diuretic resistance: rebound sodium retention, postdiuretic effect, and diuretic braking. While very few agents have joined the armamentarium and no new strategies have been developed to deal with this phenomenon, several options are available to clinicians for managing loop diuretic resistance, including salt restriction, administration of i.v. loop diuretics, continuous infusion of loop diuretics, and combination therapy using loop diuretics and thiazides.

CONCLUSION

Loop diuretic resistance presents a challenge for clinicians in the ICU setting. Strategies to improve patients' responsiveness to these agents include fluid and salt restriction, switching from oral to i.v. loop diuretics, increasing diuretic dose, continuous infusion, and combination therapy with thiazides. Several of these strategies may be used concurrently to combat diuretic resistance and promote symptomatic relief of edema in the critically ill patient.

Differences in the duration of diuretic effects and impact on the renin-angiotensin-aldosterone system of furosemide in healthy dogs

Our aim was to investigate the differences in the duration of diuretic effects and impact on the renin-angiotensin-aldosterone (RAA) system of furosemide as a model of short- and long-acting loop diuretics. Anesthetized dogs (n=6) were randomized into placebo, intravenous bolus administration (IB) and chronic rate infusion (CRI) groups. This study was conducted with a crossover study. Furosemide (4 mg/kg) was diluted to 18 mL in sterile saline. Furosemide was infused at 0.5 mg/kg/hr for 8 hr in the CRI group or was injected at 0 and 4 hr (both 2 mg/kg) in the IB group. Blood and urine samples were collected at baseline and at 1, 2, 4, 5, 6 and 8 hr. Compared with the baseline, the IB group had a significantly increased urine output at 1 and 5 hr. The CRI group had a significantly increased urine output persisting for 4 hr compared with the baseline. Compared with the placebo group, 8-hr urine output and 8-hr sodium excretion were significantly increased in the IB and CRI groups; the values in the CRI group were significantly higher than those in the IB group. Eight-hour potassium excretion was significantly increased in the IB and CRI groups. The plasma aldosterone concentration was significantly elevated in the IB group at 8 hr. Duration of action may be a predominant cause of loop diuretic-related differences. Persistent diuresis may cause greater diuretic effects than transient diuresis, with less elevation of the plasma aldosterone concentration.

A comprehensive review of the loop diuretics: should furosemide be first line?

OBJECTIVE

To review the literature regarding the pharmacokinetic profiles, comparative safety and efficacy, and comparative costs of loop diuretics to evaluate the current clinical usefulness of furosemide.

DATA SOURCES

A search of MEDLINE (1966-June 2009) was conducted using the terms furosemide, torsemide, bumetanide, ethacrynic acid, and loop diuretics. Articles were limited to those written in English.

STUDY SELECTION AND DATA EXTRACTION

All English-language articles identified from the data sources were reviewed. Studies were eligible if they encompassed pharmacokinetics, comparative safety and efficacy, or comparative costs of the loop diuretics.

DATA SYNTHESIS

In patients with heart failure (HF), torsemide demonstrated decreased mortality compared with furosemide in 1 study (2.2% vs 4.5% in the furosemide group; p < 0.05), decreased hospitalizations in 1 study (23 in the torsemide group vs 61 in the furosemide group; p < 0.01), and improved New York Heart Association functional classifications in 2 studies. In the first, 45.8% with torsemide versus 37.2% with furosemide demonstrated improvement in at least one functional class (p = 0.00017). In the second, 40.2% with torsemide and 30.7% with furosemide demonstrated improvement in at least one functional class (p = 0.014). In 2 of 3 studies of patients with cirrhosis, torsemide increased natriuresis and total volume diuresed compared with furosemide in patients with cirrhosis; however, no significant difference between the agents with respect to plasma renin and aldosterone concentrations was demonstrated. In patients with pulmonary hypertension, central venous pressure, capillary wedge pressure, and stroke volume significantly improved from baseline among patients who received torsemide, but not in those who received furosemide, although the intergroup analysis failed to reach statistical significance. Among patients with chronic kidney disease, no significant differences were noted with respect to natriuresis and blood pressure control between the 2 agents; however, in patients with acute kidney injury, patients who received furosemide had a significant improvement in urine output versus the torsemide group. Additionally, 2 trials comparing bumetanide with furosemide were identified, although the results were conflicting. In patients with nephrotic syndrome, bumetanide significantly improved weight loss in the first 4 weeks and in week 20, compared with furosemide. In patients with HF, significant improvement in dyspnea at rest and on exertion was exhibited in the bumetanide group, but not in the furosemide group; no significant difference was noted between the 2 groups when evaluating global assessment.

CONCLUSIONS

Growing evidence demonstrates more favorable pharmacokinetic profiles of torsemide and bumetanide compared with furosemide. Furthermore, torsemide may be more efficacious and safer than furosemide in patients with HF. A trial comparing all 3 drugs would be required to confirm torsemide as the primary loop diuretic in patients with HF, but based upon limited current evidence, we recommend torsemide over furosemide. Currently, little evidence exists to support either torsemide or bumetanide as first-line treatment over furosemide in patients with other edematous disease states.

Beneficial effects of torasemide on systolic wall stress and sympathetic nervous activity in asymptomatic or mildly symptomatic patients with heart failure: comparison with azosemide

Loop diuretics could adversely influence prognosis due to activation of neurohumoral mechanism in the long term. Previous study showed torasemide, a loop diuretic with anti-aldosteronergic properties, was associated with lower mortality in patients with chronic heart failure (CHF). We evaluated the effects of torasemide, in comparison with azosemide, in patients with CHF. Patients received oral diuretic therapy with torasemide (8 mg/d, n = 15) or azosemide (60 mg/d, n = 15) for 3 months. Torasemide and azosemide were then switched, and the patients were treated for another 3 months. Torasemide treatment induced significant decreases in left ventricular (LV) systolic wall stress (from 259 +/- 95 to 232 +/- 80 kdyn/cm2) and the plasma level of aldosterone (from 133 +/- 61 to 95 +/- 50 pg/mL) and was not associated with a change in the plasma level of norepinephrine. In contrast, the plasma level of norepinephrine was significantly increased (from 370 +/- 170 to 481 +/- 247 pg/mL), whereas LV systolic wall stress was unchanged after azosemide treatment. This study indicates that torasemide treatment reduced LV systolic wall stress without activation of the sympathetic nervous system in patients with CHF. The anti-aldosteronergic properties of torasemide may contribute to its favorable effects.

[Effects of various diuretics on cardiac function in rats with heart failure]

Torasemide is a long-acting loop diuretic that combines the effects of both furosemide and spironolactone. It has been reported that torasemide but not furosemide might attenuate myocardial remodeling accompanied by left ventricular (LV) dysfunction. However, nothing is known about the effect of torasemide, long-acting loop diuretic and spironolactone, an aldosterone receptor antagonist in a rat model of chronic heart failure (CHF). Therefore, we compared the therapeutic effects of torasemide, furosemide and spironolactone on the progression of LV remodeling in a rat model of CHF after experimental autoimmune myocarditis (EAM). EAM was elicited in Lewis rats by immunization with porcine cardiac myosin. Twenty-eight days after immunization, rats were treated for 28 days with torasemide, furosemide and spironolactone. Diuretic actions, heart weight/body weight, heart rate, mean blood pressure, myocardial function by echocardiography, cardiac fibrosis, myocyte diameter and cardiac aldosterone synthetase (CYP11B2) were evaluated. Increased cardiac CYP11B2, severe LV remodeling and resultant cardiac dysfunction was found in CHF rats, whereas decreased cardiac CYP11B2, less remodeling and improvement of cardiac function were found in torasemide- and spironolactone-treated CHF rats. Our results indicate that torasemide and spironolactone treatment significantly improved cardiac function and LV remodeling compared with furosemide treatment.

Torsemide Versus Furosemide After Continuous Renal Replacement Therapy Due to Acute Renal Failure in Cardiac Surgery Patients

Diuretic therapy in ARF (acute renal failure) is mainly done with loop diuretics, first of all furosemide. Torsemide has a longer duration of action and does not accumulate in renal failure. In chronic and acute renal failure, both diuretics have been effectively applied, with a more pronounced diuretic effect for torsemide. In this study, the effects of torsemide versus furosemide on renal function in cardiac surgery patients recovering from ARF after continuous renal replacement therapy (CRRT) were studied. Twenty-nine critically ill patients admitted to an intensive care unit at a university teaching hospital after cardiac surgery recovering from ARF after CRRT were included in this prospective, controlled, single-center, open-labeled, randomized clinical trial. Inclusion criteria were urine output >0.5 mL/kg/h over 6 h under CRRT. Torsemide and furosemide dosages were adjusted with the target urine output being 0.8-1.5 mL/kg/h. Hemodynamic data, urine output, volume balance, serum creatinine clearance, electrolytes, blood urea nitrogen, serum creatinine, renin, and aldosterone concentrations were measured. Fourteen patients were included in the furosemide group and 15 patients in the torsemide group. Dosages of 29 (0-160) mg torsemide and a dosage of 60 (0-240) mg furosemide were given every 6 h in each group, respectively. The dosage given at the end of the study decreased significantly in furosemide and torsemide treated patients. Urine output, 24 h balance, and serum creatinine clearance did not differ significantly between groups. Urine output decreased in both groups, mostly dose-dependent in the torsemide group. The intragroup comparison of the first time-interval after inclusion with the last time-interval showed a significant increase in serum creatinine and blood urea nitrogen in the furosemide group. Renin and aldosterone concentrations did not show significant differences. In conclusion, torsemide and furosemide were effective in increasing urine output. Torsemide might show a better dose-dependent diuretic effect in ARF patients after CRRT treatment. Serum creatinine and blood urea nitrogen elimination were less pronounced in the furosemide group.

4-(3-Methyl-anilino)-N-[N-(1-methyl-ethyl)carbamo-yl]pyridinium-3-sulfon-amidate (torasemide) methanol 0.25-solvate 0.25-hydrate

The title compound, C(16)H(20)N(4)O(3)S·0.25CH(4)O·0.25H(2)O, is a hydrate/methanol solvate of torasemide, a diuretic drug used in the treatment of hypertension. The asymmetric unit contains two torasemide mol-ecules and half-occupied methanol and water mol-ecules. It is isomorphous with the previously reported nonsolvated T-II form of torasemide. The water mol-ecules contribute to the stability of the structure by participating in an extensive system of O-H⋯O hydrogen bonds; N-H⋯N and N-H⋯O hydrogen bonds are also present. Both asymmetric mol-ecules of torasemide form inversion dimers in the crystal.

Determinants of steady-state torasemide pharmacokinetics: impact of pharmacogenetic factors, gender and angiotensin II receptor blockers

BACKGROUND

Torasemide is frequently used for the treatment of hypertension and heart failure. However, the determinants of torasemide pharmacokinetics in patients during steady-state conditions are largely unknown. We therefore explored the impact of genetic polymorphisms of cytochrome P450 (CYP) 2C9 (CYP2C9) and organic anion transporting polypeptide (OATP) 1B1 (SLCO1B1), gender, and the effects of losartan and irbesartan comedication on the interindividual variability of steady-state pharmacokinetics of torasemide.

PATIENTS AND METHODS

Twenty-four patients receiving stable medication with torasemide 10 mg once daily and with an indication for additional angiotensin II receptor blocker (ARB) treatment to control hypertension or to treat heart failure were selected. Blood samples were taken before torasemide administration and 0.5, 1, 2, 4, 8, 12 and 24 hours after administration. After this first study period, patients received either irbesartan 150 mg (five female and seven male patients aged 69+/-8 years) or losartan 100 mg (two female and ten male patients aged 61+/-8 years) once daily. After 3 days of ARB medication, eight blood samples were again collected at the timepoints indicated above. The patients' long-term medications, which did not include known CYP2C9 inhibitors, were maintained at a constant dose during the study. All patients were genotyped for CYP2C9 (*1/*1 [n=15]; *1/*2 [n = 4]; *1/*3 [n=5]) as well as for SLCO1B1 (c.521TT [n=13]; c.521TC [n=11]).

RESULTS

Factorial ANOVA revealed an independent impact of the CYP2C9 genotype (dose-normalized area under the plasma concentration-time curve during the 24-hour dosing interval at steady state [AUC(24,ss)/D]: *1/*1 375.5+/-151.4 microg x h/L/mg vs *1/*3 548.5+/-271.6 microg x h/L/mg, p=0.001), the SLCO1B1 genotype (AUC(24,ss)/D: TT 352.3+/-114 microg x h/L/mg vs TC 487.6+/-218.4 microg x h/L/mg, p<0.05) and gender (AUC(24,ss)/D: males 359.5+/-72.2 microg x h/L/mg vs females 547.3+/-284 microg x h/L/mg, p<0.01) on disposition of torasemide. Coadministration of irbesartan caused a 13% increase in the AUC(24,ss)/D of torasemide (p=0.002), whereas losartan had no effect.

CONCLUSION

This study shows that the CYP2C9*3 and SLCO1B1 c.521TC genotype and female gender are significant and independent predictors of the pharmacokinetics of torasemide. Coadministration of irbesartan yields moderate but significant increases in the torasemide plasma concentration and elimination half-life.

Diagnosis and treatment of myocardial fibrosis in hypertensive heart disease

Although hypertensive heart disease (HHD) is clinically characterized by development of left ventricular hypertrophy in the absence of a cause other than arterial hypertension, changes in the composition of myocardial tissue also develop in arterial hypertension, leading to structural remodeling of the myocardium (eg, fibrosis). Myocardial fibrosis is the major determinant of diastolic dysfunction/failure in patients with HHD. Recent available data on the determination of serum concentrations of collagen-derived serum peptides, as well as quantitative analysis of echoreflectivity to address the presence of fibrosis in the myocardium of hypertensive patients, are promising. In addition, preliminary data suggest that the goal of reducing myocardial fibrosis is achievable using specific pharmacological agents in patients with HHD.

Treatment of hypertension in heart failure with preserved ejection fraction: role of the kidney

Heart failure can present clinically as primarily diastolic or systolic dysfunction or both. There is an increasing awareness that heart failure can occur in the presence of a normal left ventricular ejection fraction. Heart failure with normal left ventricular ejection fraction is frequently referred to as diastolic heart failure because of the presence of diastolic left ventricular dysfunction evident from impaired left ventricular relaxation. This article focuses on the treatment of hypertension and the role the kidney plays in selecting appropriate agents.