The effects of diuresis on the pharmacokinetics of the loop diuretics furosemide and torsemide in patients with heart failure

Treatment strategies for diuretic resistance in patients with heart failure

Improving congestion with diuretic therapy is crucial in the treatment of heart failure (HF). However, despite the use of loop diuretics, diuresis may be inadequate and congestion persists, which is known as diuretic resistance. Diuretic resistance and residual congestion are associated with a higher risk of rehospitalization and mortality. Causes of diuretic resistance in HF include diuretic pharmacokinetic changes, renal hemodynamic perturbations, neurohumoral activations, renal tubular remodeling, and use of nephrotoxic drugs as well as patient comorbidities. Combination diuretic therapy (CDT) has been advocated for the treatment of diuretic resistance. Thiazides, acetazolamides, tolvaptan, mineralocorticoid receptor antagonist, and sodium-glucose co-transporter-2 inhibitors are among the candidates, but none of these treatments has yet demonstrated significant diuretic efficacy or improved prognosis. At present, it is essential to identify and treat the causes of diuretic resistance in individual patients and to use CDT based on a better understanding of the characteristics of each drug to achieve adequate diuresis. Further research is needed to effectively assess and manage diuretic resistance and ultimately improve patient outcomes.

A Systematic Critical Review of Clinical Pharmacokinetics of Torasemide

PURPOSE

Torasemide is a potassium-sparing loop diuretic used to treat fluid retention associated with congestive heart failure and kidney and hepatic diseases. This systematic review was conducted to combine all accessible data on the pharmacokinetics (PK) of torasemide in healthy and diseased populations, which may help clinicians avert adverse drug reactions and determine the correct dosage regimen.

METHODS

Four databases were systematically searched to screen for studies associated with the PK of torasemide, and 21 studies met the eligibility criteria. The review protocol was registered in the PROSPERO database (CRD42023390178).

RESULTS

A decrease in maximum plasma concentration (C max ) was observed for torasemide after administration of the prolonged-release formulation in comparison to that after administration of the immediate-release formulation, that is, 1.12 ± 0.17 versus 1.6 ± 0.2 mcg/mL. After administering an oral dose of torasemide, a 2-fold increase in the area under the concentration-time curve (AUC) was reported in patients with congestive heart failure compared with the healthy population. Moreover, the patients with renal failure (clearance < 30 mL/min) showed an increase in value of AUC 0-∞ that is, 42.9 versus 8.091 mcg.h -1 .mL -1 compared with healthy subjects. In addition, some studies have reported interactions with different drugs, in which irbesartan showed a slight increase in the AUC 0-∞ of torasemide, whereas losartan and empagliflozin did not.

CONCLUSIONS

The current review summarizes all available PK parameters of torasemide that may be beneficial for avoiding drug-drug interactions in subjects with renal and hepatic dysfunction and for predicting doses in patients with different diseases.

Congestion in Heart Failure: From the Secret of a Mummy to Today's Novel Diagnostic and Therapeutic Approaches: A Comprehensive Review

This review paper presents a review of the evolution of this disease throughout the centuries, describes and summarizes the pathophysiologic mechanisms, briefly discusses the mechanism of action of diuretics, presents their role in decongesting heart failure in patients, and reveals the data behind ultrafiltration in the management of acutely or chronically decompensated heart failure (ADHF), focusing on all the available data and advancements in this field. Acutely decompensated heart failure (ADHF) presents a critical clinical condition characterized by worsening symptoms and signs of heart failure, necessitating prompt intervention to alleviate congestion and improve cardiac function. Diuretics have traditionally been the mainstay for managing fluid overload in ADHF. Mounting evidence suggests that due to numerous causes, such as coexisting renal failure or chronic use of loop diuretics, an increasing rate of diuretic resistance is noticed and needs to be addressed. There has been a series of trials that combined diuretics of different categories without the expected results. Emerging evidence suggests that ultrafiltration may offer an alternative or adjunctive approach.

A novel opportunity to improve heart failure care: focusing on subcutaneous furosemide

The prevalence of heart failure (HF) continues to rise in developed nations. Symptomatic congestion is the most common reason for patients to seek medical attention, and management often requires intravenous (IV) diuretic administration in the hospital setting. Typically, the number of admissions increases as the disease progresses, not only impacting patient survival and quality of life but also driving up healthcare expenditures. pH-neutral furosemide delivered subcutaneously using a proprietary, single-use infusor system (Furoscix) has a tremendous potential to transition in-hospital decongestive therapy to the outpatient setting or to the patient's home. This review is aimed at providing an overview of the pharmacodynamic and pharmacokinetic profile of the novel pH-neutral furosemide in addition to the most recent clinical trials demonstrating its benefit when used in the home setting. Given the newest data and approval by the Food and Drug Administration in the US, it has the potential to revolutionize the care of patients with decompensated HF. Undoubtedly, it will lead to improved quality of life as well as significantly reduced healthcare costs related to hospital admissions.

Usefulness of urinary potassium to creatinine ratio to predict diuretic response in patients with acute heart failure and preserved ejection fraction

BACKGROUND

Patients with acute heart failure (AHF) require intensification in the diuretic strategy. However, the optimal diuretic strategy remains unclear. In this work, we aimed to evaluate the role of urinary potassium to creatinine ratio (K/Cr) to predict diuretic and natriuretic response to thiazide or mineralocorticoid receptor antagonists (MRAs) in a cohort of patients with AHF and preserved ejection fraction (AHF-pEF).

HYPOTHESIS

Patients with a high urinary K/Cr ratio will have a better diuretic and natriuretic response with spironolactone versus chlorthalidone.

METHODS

This is a study of 44 patients with AHF-pEF with suboptimal loop diuretic response. The primary endpoint was the baseline K/Cr associated with natriuretic and diuretic effect of chlorthalidone versus spironolactone at 24 and 72 h. Mixed linear regression models were used to analyze the endpoints. Estimates were reported as least squares mean with their respective 95% confidence interval (CIs).

RESULTS

The median age of the study population was 85 years (82.5-88.5), and 30 (68.2%) were women. The inferential multivariate analysis suggested a greater natriuretic and diuretic effect of chlorthalidone across K/Cr levels. In the upper category, chlorthalidone translated into a statistically increase in natriuresis at 24 and 72 h. Chlorthalidone versus spironolactone showed ∆uNa of 25.7 mmol/L at 24 h (95% CI = -3.7 to 55.4, p = .098) and ∆uNa of 24.8 mmol/L at 72 h (95% CI = -4 to 53.6, p = .0106). The omnibus p value is .027. Multivariate analyses revealed a significant increase in 72 h cumulative diuresis irrespective of K/Cr status in those on chlorthalidone.

CONCLUSIONS

In patients with AHF-pEF and suboptimal diuretic response, diuresis and natriuresis are higher with the administration of chlorthalidone over spironolactone. These data don't support the hypothesis that the K/Cr ratio can help guide the choice of thiazide diuretic versus MRA in AHF-pEF patients on loop diuretic.

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.

Subcutaneous furosemide for the treatment of heart failure: a state-of-the art review

The prevalence of heart failure (HF) is on the rise. By 2030, over eight million Americans (46% increase from current prevalence) will have heart failure. In the USA, approximately 30 billion dollars is spent annually on heart failure and this number will likely double in 2030. Thus, HF represents a significant economic burden. Acute decompensated heart failure (ADHF) is a clinical spectrum, which refers to increasing symptoms and signs of heart failure prompting an emergency room visit or hospitalization. In ADHF, inpatient administration of intravenous diuretic is the standard of care due to the variability in the absorption of oral diuretics. Within 30 days, 25-30% of these patients are readmitted with recurrent ADHF. Recent efforts have focused in reducing HF readmission, and thereby decreasing costs; hence, innovative outpatient treatment options have emerged. Subcutaneous furosemide use will potentially overcome the need to place intravenous lines, reduce associated expenses, and enable management of ADHF at home. This review presents data on the pharmacodynamics and pharmacokinetics of subcutaneous furosemide, scientific evidence on the use of this therapy in the palliative and hospice population, and its experimental use as an outpatient therapy and/or as a bridge from inpatient to home.

Outpatient treatment of worsening heart failure with intravenous and subcutaneous diuretics: a systematic review of the literature

Aims

In the coming decade, heart failure (HF) represents a major global healthcare challenge due to an ageing population and rising prevalence combined with scarcity of medical resources and increasing healthcare costs. A transitional care strategy within the period of clinical worsening of HF before hospitalization may offer a solution to prevent hospitalization. The outpatient treatment of worsening HF with intravenous or subcutaneous diuretics as an alternative strategy for hospitalization has been described in the literature.

Methods and results

In this systematic review, the available evidence for the efficacy and safety of outpatient treatment with intravenous or subcutaneous diuretics of patients with worsening HF is analysed. A search was performed in the electronic databases MEDLINE and EMBASE. Of the 11 included studies 10 were single‐centre, using non‐randomized, observational registries of treatment with intravenous or subcutaneous diuretics for patients with worsening HF with highly variable selection criteria, baseline characteristics, and treatment design. One study was a randomized study comparing subcutaneous furosemide with intravenous furosemide. In a total of 984 unique individual patients treated in the reviewed studies, only a few adverse events were reported. Re‐hospitalization rates for HF at 30 and 180 days were 28 and 46%, respectively. All‐cause re‐hospitalization rates at 30 and 60 days were 18–37 and 22%, respectively. The highest HF re‐hospitalization was 52% in 30 days in the subcutaneous diuretic group and 42% in 30 days in the intravenous diuretic group.

Conclusions

The reviewed studies present practice‐based results of treatment of patients with worsening HF with intravenous or subcutaneous diuretics in an outpatient HF care unit and report that it is effective by relieving symptoms with a low risk of adverse events. The studies do not provide satisfactory evidence for reduction in rates of re‐hospitalization or improvement in mortality or quality of life. The conclusions drawn from these studies are limited by the quality of the individual studies. Prospective randomized studies are needed to determine the safety and effectiveness of outpatient intravenous or subcutaneous diuretic treatment for patient with worsening HF.

Subcutaneous Furosemide in Heart Failure: Pharmacokinetic Characteristics of a Newly Buffered Solution

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Parenteral diuretics form the cornerstone of treatment of fluid overload in heart failure. The alkaline pH of furosemide USP precludes SC administration.

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A novel buffered formulation of furosemide (pH 7.4) was developed for SC infusion using a wearable patch pump.

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A 5-h biphasic SC infusion (30 mg in hour 1 followed by 12.5 mg/h for 4 h) of the novel formulation was tested in 2 clinical studies.

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Following SC administration, therapeutic levels of furosemide were reached within 30 min and maintained for up to 6 h. This resulted in complete bioavailability and equivalent diuresis when compared with 80 mg of intravenous furosemide.

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A novel strategy using SC administration of buffered furosemide is introduced for outpatient use, including self-administration at home. This may help to reduce the patient and economic burden of heart failure.

Parenteral diuretics form the cornerstone of decongestion in heart failure. However, parenteral therapy routinely requires emergency room or inpatient care. A novel buffered furosemide formulation with neutral pH was developed to offer “hospital-strength” diuresis for outpatient use, including self-administration at home. Subcutaneous infusion using a biphasic delivery profile resulted in complete bioavailability (99.65%) and equivalent diuresis when compared with intravenous administration. Subcutaneous administration of buffered furosemide was well tolerated with no evidence of any drug-induced skin reactions. Subcutaneous infusion of buffered furosemide in the outpatient setting or home may help to reduce the burden of heart failure.

A perspective on diuretic resistance in chronic congestive heart failure

Chronic congestive heart failure (CHF) is a complex disorder characterized by inability of the heart to keep up the demands on it, followed by the progressive pump failure and fluid accumulation. Although the loop diuretics are widely used in heart failure (HF) patients, both pharmacodynamic and pharmacokinetic alterations are thought to be responsible for diuretic resistance in these patients. Strategies to overcome diuretic resistance include sodium intake restriction, changes in diuretic dose and route of administration and sequential nephron diuretic therapy. In this review, we discuss the definition, prevalence, mechanism of development and management strategies of diuretic resistance in HF patients.

Observation of Patients Transitioned to an Oral Loop Diuretic Before Discharge and Risk of Readmission for Acute Decompensated Heart Failure

BACKGROUND

Heart failure (HF) is associated with high 30-day readmission rates and places significant financial burden on the health care system. The aim of this study was to determine if the duration of observation on an oral loop diuretic before discharge is associated with a reduction in 30-day HF readmission in patients with acute decompensated HF (ADHF).

METHODS AND RESULTS

This was a retrospective study of adult patients admitted for ADHF at a large academic medical center. A total of 123 patients were included. Baseline characteristics were similar between groups. The primary outcome of 30-day HF readmission occurred in 11 of 61 patients (18%) observed on an oral loop diuretic for <24 hours and in 2 of 62 patients (3.2%) observed on an oral loop diuretic for ≥24 hours (P = .023). Readmissions for 60- and 90-day HF were also significantly lower in patients observed for ≥24 hours (P = .014 and P = .049, respectively). Associations became stronger after multivariate analysis (P < .001). Observation for <24 hours and previous admission within 30 days were independent predictors of 30-day HF readmission (P = .03).

CONCLUSIONS

Observation of patients on an oral loop diuretic for <24 hours was associated with significantly higher 30-day HF readmission. Therefore, observation on an oral loop diuretic for ≥24 hours before discharge in patients presenting with ADHF should be strongly considered.

Treating Diuretic Resistance: An Overview

Loop diuretics are central to the management of fluid overload in acute decompensated heart failure. However, a variance in the response to loop diuretics can alter a patient's clinical course and has an adverse effect on clinical outcomes. Thus, a diminished response to loop diuretics is an important clinical issue. Factors thought to contribute to diuretic resistance include erratic oral absorption in congested states and postdiuretic sodium retention. Further contributing to diuretic resistance in patients with advanced heart failure are decreases in renal perfusion and alterations in sodium handling that occur in an attempt to maintain circulatory homeostasis. Several pharmacologic interventions have been used to improve diuretic response. Intravenous diuretic administration, increasing diuretic doses, or changing diuretic agents can potentially overcome pharmacokinetic obstacles which contribute to drug resistance. Combination diuretic therapy may be useful to overcome increased sodium retention, dopamine may improve renal perfusion, and hypertonic saline may transiently increase intravascular volume and improve sodium delivery to the tubules of the nephron. Despite the prevalence of diuretic resistance, there remains a paucity of clinical trial evidence to help guide therapy in these patients.

Dilemmas in the Dosing of Heart Failure Drugs: Titrating Diuretics in Chronic Heart Failure

Despite advances in medical therapy over the past few decades, the incidence of heart failure hospitalisation continues to rise. Diuretics are the most common therapy used to treat heart failure as they relieve congestion. However, there is a lack of guidance on how to best use these medications. Guidelines support the use of diuretics at the lowest clinically effective dose but do not specify a diuretic strategy beyond that. Here we review the diuretics available for treatment, potential mechanisms of diuretic resistance and ways to address this in the ambulatory setting, and review tools that have been developed to help guide diuretic use in the treatment of chronic heart failure.

Management of Cardio-Renal Syndrome and Diuretic Resistance

OPINION STATEMENT

Diuretic resistance in acute heart failure has emerged as a powerful predictor of adverse outcome, which is often independent of underlying glomerular filtration rate (GFR). Metrics of diuretic efficacy differ in their accuracy, convenience, and biological plausibility, which should be taken into account when interpreting their results. Loop diuretic efficacy depends on adequate delivery of both the pharmacological agent itself and its substrate (i.e., sodium chloride) to the loop diuretic site of action at the luminal side of the thick ascending limb of Henle's loop. This requires an adequate dosing strategy, with higher doses needed when GFR is low. Importantly, the kidneys are able only to regulate the effective circulatory volume. Thus, specific problems of intravascular volume depletion and poor cardiac output with impaired renal perfusion should be addressed. Addition of thiazide-type diuretics should be considered when a progressive decrease in loop diuretic efficacy is observed with prolonged use (i.e., the braking phenomenon). Furthermore, thiazide-type diuretics are a useful addition in patients with low GFR to maximally boost fractional sodium excretion when nephron perfusion is poor. However, thiazide-type diuretics limit free water excretion and should be withheld in cases of hypotonic hyponatremia. Mineralocorticoid receptor antagonists (MRA) and acetazolamide are interesting options to increase loop diuretic efficacy, but further study is needed to assess whether improved diuretic efficacy also translates into clinical outcome benefits. Finally, ultrafiltration should be considered in patients with refractory diuretic resistance as persistent volume overload after decongestive treatment is associated with worse outcomes. Whether more upfront use of individually tailored ultrafiltration is superior to pharmacological therapy remains to be shown by adequately powered randomized clinical trials.

Intravenous Furosemide for Acute Decompensated Congestive Heart Failure: What Is the Evidence?

Use of intravenous furosemide rather than oral administration in acute decompensated congestive cardiac failure is universally recommended in international guidelines. We argue that this recommendation is not supported by the existing evidence, and suggest that trials should be performed to determine whether larger doses of oral furosemide should be prescribed prior to an IV switch. This could reduce length of hospital admissions and allow for more patients to be managed in the primary care setting.

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.

Apical voltage-driven urate efflux transporter NPT4 in renal proximal tubule

Uric acid (urate) is the end product of purine metabolism in humans. Human kidneys reabsorb a large proportion of filtered urate. This extensive renal reabsorption, together with the fact that humans do not possess uricase that catalyzes the biotransformation of urate into allantoin, results in a higher plasma urate concentration in humans compared to other mammals. A major determinant of plasma urate concentration is renal excretion as a function of the balance between reabsorption and secretion. We previously identified that renal urate absorption in proximal tubular epithelial cells occurs mainly via apical urate/anion exchanger, URAT1/SLC22A12, and by facilitated diffusion along the trans-membrane potential gradient by the basolateral voltage-driven urate efflux transporter, URATv1/SLC2A9/GLUT9. In contrast, the molecular mechanism by which renal urate secretion occurs remains elusive. Recently, we reported a newly characterized human voltage-driven drug efflux transporter, hNPT4/SLC17A3, which functions as a urate exit pathway located at the apical side of renal proximal tubules. This transporter protein has been hypothesized to play an important role with regard to net urate efflux. An in vivo role of hNPT4 is supported by the fact that missense mutations in SLC17A3 present in hyperuricemia patients with urate underexcretion abolished urate efflux capacity in vitro. Herein, we report data demonstrating that loop diuretics and thiazide diuretics substantially interact with hNPT4. These data provide molecular evidence for loop and thiazide-diuretics-induced hyperuricemia. Thus, we propose that hNPT4 is an important transepithelial proximal tubular transporter that transports diuretic drugs and operates functionally with basolateral organic anion transporters 1/3 (OAT1/OAT3).

Effects of the rate and composition of fluid replacement on the pharmacokinetics and pharmacodynamics of intravenous torasemide

The effects of differences in the rate and composition of intravenous fluid replacement for urine loss on the pharmacokinetics and pharmacodynamics of torasemide were evaluated in rabbits. Each rabbit received 2-h constant intravenous infusion of 1 mg kg−1 torasemide with 0% replacement (treatment 1, n = 6), 50% replacement (treatment 2, n = 9), 100% replacement with lactated Ringer's solution (treatment 3, n = 8), and 100% replacement with 5% dextrose in water (treatment 4, n = 6). Total body (4.53, 5.72, 10.0 and 4.45 mL min−1 kg−1 for treatments 1–4, respectively) and renal clearance (1.44, 1.87, 6.78 and 1.72 mL min−1 kg−1) of torasemide, and total amount of unchanged torasemide excreted in 8-h urine (Ae 0–8 h: 694, 780, 1310 and 1040 μg) in treatment 3 were considerably faster and greater compared with treatments 1, 2 and 4. Although the difference in Ae 0–8 h between treatments 1 and 3 was only 88.8%, the diuretic and/or natriuretic effects of torasemide were markedly different among the four treatments. For example, the mean 8-h urine output was 101, 185, 808 and 589 mL for treatments 1–4, respectively, and the corresponding values for sodium excretion were 10.1, 20.6, 89.2 and 29.9 mmol, and for chloride excretion were 14.5, 27.9, 94.0 and 37.2 mmol. Although full fluid replacement was used in both treatments 3 and 4, the 8-h diuretic, natriuretic and chloruretic effects in treatment 3 were significantly greater compared with treatment 4, indicating the importance of the composition of fluid replacement. Both treatments 1 and 4 received no sodium replacement, however, the 8-h diuretic, natriuretic and chloruretic effects were significantly greater in treatment 4 compared with treatment 1, indicating the importance of rate of fluid replacement for the diuretic effects. Therefore, the 8-h diuretic, natriuretic and chloruretic effects were significantly greater in treatment 3 compared with treatments 1, 2 and 4, indicating the importance of full fluid and electrolyte replacement. Some implications for the bioequivalence evaluation of dosage forms of torasemide are discussed.

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.

Drug Absorption in the Management of Congestive Heart Failure: Loop Diuretics

Congestive heart failure is a disease state distinguished by the regular presence of both renal and hepatic abnormalities in drug handling. One such abnormality involves flaws in the process of drug absorption. In most instances, congestive heart failure-related abnormalities in drug absorption are of inconsequential significance. However, this is not the case with loop diuretics. Loop diuretic action ordinarily tracks the rate and extent of absorption if a sufficient amount of diuretic has been given to exceed the threshold for diuretic effect. In congestive heart failure, both the rate and absolute amount of loop diuretic absorbed can be reduced as a function of the heart failure state itself. In this setting, drug dissolution characteristics can assume added significance. Furosemide is the loop diuretic with the widest intra- and interpatient variability of absorption. Alternatively, the loop diuretic torsemide is rapidly and fairly completely absorbed independent of the heart failure state. This pattern of absorption establishes it as the preferred loop diuretic in the otherwise diuretic-resistant heart failure patient. However, the exact role of torsemide in the outpatient management of congestive heart failure remains to be determined.

Acute decompensated heart failure: a contemporary approach to pharmacotherapeutic management

Hospital admissions for acute decompensated heart failure (ADHF) have increased precipitously during the past few decades and are projected to continue to increase in the future. To optimize patient outcomes and reduce the costs associated with this disorder, evidenced-based pharmacotherapy is essential. Continuous infusions of loop diuretic therapy rather than bolus dosing may enhance efficacy and reduce the extent of diuretic resistance. Nesiritide is a pharmacologically novel preload and afterload reducer but based on clinical trial evidence should be reserved for those unable to take or with resistance to intravenous nitrate therapy. Catecholamine- and phosphodiesterase-based inotropic therapies are efficacious, but the increased risk of arrhythmogenesis and the potential for negative survival effects limit their use. The experimental agent levosimendan is a positive inotropic agent but does not increase myocyte calcium concentrations as do catecholamines or phosphodiesterase inhibitors. Clinical trial evidence demonstrates a positive survival benefit for levosimendan versus dobutamine.

Diuretic resistance predicts mortality in patients with advanced heart failure

BACKGROUND

In patients with chronic heart failure (CHF), diuretic requirements increase as the disease progresses. Because diuretic resistance can be overcome with escalating doses, the evaluation of CHF severity and prognosis may be incomplete without considering the intensity of therapy.

METHODS

The prognostic importance of diuretic resistance (as evidenced by a high-dose requirement) was retrospectively evaluated in 1153 patients with advanced CHF who were enrolled in the Prospective Randomized Amlodipine Survival Evaluation (PRAISE). The relation of loop diuretic and angiotensin-converting enzyme inhibitor doses (defined by their median values) and other baseline characteristics to total and cause-specific mortality was determined by proportion hazards regression.

RESULTS

High diuretic doses were independently associated with mortality, sudden death, and pump failure death (adjusted hazard ratios [HRs] 1.37 [P =.004], 1.39 [P =.042], and 1.51 [P =.034], respectively). Use of metolazone was an independent predictor of total mortality (adjusted HR = 1.37, P =.016) but not of cause-specific mortality. Low angiotensin-converting enzyme inhibitor dose was an independent predictor of pump failure death (adjusted HR = 2.21, P =.0005). Unadjusted mortality risks of congestion and its treatment were additive and comparable to those of established risk factors.

CONCLUSIONS

The independent association of high diuretic doses with mortality suggests that diuretic resistance should be considered an indicator of prognosis in patients with chronic CHF. These retrospective observations do not establish harm or rule out a long-term benefit of diuretics in CHF, because selection bias may entirely explain the relation of prescribed therapy to death.

Pharmacotherapy in congestive heart failure: diuretic resistance and strategies to overcome resistance in patients with congestive heart failure

Congestive heart failure is a complex clinical hemodynamic disorder characterized by chronic and progressive pump failure and fluid accumulation. Although the overall impact of diuretic therapy on congestive heart failure mortality remains unknown, diuretics remain a vital component of symptomatic congestive heart failure management. Over time, sodium and water excretion are equalized before adequate fluid elimination occurs. This phenomenon is thought to occur in one out of three patients with congestive heart failure on diuretic therapy and is termed diuretic resistance. In congestive heart failure, both pharmacokinetic and pharmacodynamic alterations are thought to be responsible for diuretic resistance. Due to disease chronicity, symptomatic management is vital to improved quality of life and enhancing diuretic response is therefore pivotal.

Open-label randomized trial of torsemide compared with furosemide therapy for patients with heart failure

PURPOSE

Because the bioavailability of oral furosemide is erratic and often incomplete, we tested the hypothesis that patients with heart failure who were treated with torsemide, a predictably absorbed diuretic, would have more favorable clinical outcomes than would those treated with furosemide.

PATIENTS AND METHODS

We conducted an open-label trial of 234 patients with chronic heart failure (mean [+/- SD] age, 64 +/- 11 years) from an urban public health care system. Patients received oral torsemide (n = 113) or furosemide (n = 121) for 1 year. The primary endpoint was readmission to the hospital for heart failure. Secondary endpoints included readmission for all cardiovascular causes and for all causes, numbers of hospital days, and health-related quality of life.

RESULTS

Compared with furosemide-treated patients, torsemide-treated patients were less likely to need readmission for heart failure (39 [32%] vs. 19 [17%], P <0.01) or for all cardiovascular causes (71 [59%] vs. 50 [44%], P = 0.03). There was no difference in the rate of admissions for all causes (92 [76%] vs. 80 [71%], P = 0.36). Patients treated with torsemide had significantly fewer hospital days for heart failure (106 vs. 296 days, P = 0.02). Improvements in dyspnea and fatigue scores from baseline were greater among patients treated with torsemide, but the differences were statistically significant only for fatigue scores at months 2, 8, and 12.

CONCLUSIONS

Compared with furosemide-treated patients, torsemide-treated patients were less likely to be readmitted for heart failure and for all cardiovascular causes, and were less fatigued. If our results are confirmed by blinded trials, torsemide may be the preferred loop diuretic for patients with chronic heart failure.