Tolvaptan for the treatment of heart failure: a review of the literature

Introduction: It has been > 25 years since it was first discovered that arginine vasopressin levels are elevated in heart failure and this elevation is proportional to the severity of heart failure. Tolvaptan is an oral nonpeptide V₂-selective antagonist and has been shown to induce free water excretion without increasing urine sodium, an effect termed ‘aquaresis’.

Areas covered: This paper aims to review the physiology, chemistry, pharmacokinetics, clinical efficacy and safety of tolvaptan in HF. A PubMed literature search was performed using ‘tolvaptan’ and the MeSH term ‘heart failure’, yielding 89 references.

Expert opinion: Clinical trials conducted in ambulatory and hospitalized patients with HF have found treatment with tolvaptan causes rapid and sustained body weight reductions concurrent with increases in urine output, improves and/or normalizes serum sodium in hyponatremic patients, reduces signs and symptoms of congestion and increases thirst. However, tolvaptan has not been shown to decrease HF re-hospitalization or mortality. As an adjunct to standard therapy, tolvaptan is unique in that it is virtually the only novel agent tested in patients hospitalized for acute heart failure syndrome (AHFS) to reach its primary end point for short-term efficacy without causing deleterious side effects. There is theoretical concern that chronic V₂ receptor blockade may cause harmful long-term side effects via enhanced V_1a receptor activation, potentially offsetting any favorable effects on congestion and hyponatremia. The ‘vaptan’ class of drugs is an active and promising area for clinical investigation and future research is necessary to clarify the therapeutic role of selective and nonselective vasopressin inhibition in chronic HF and AHFS.     

Is vasopressin-receptor antagonism an advancement in the treatment of heart failure?

Despite diuretics being used to relieve the fluid retention/congestion associated with heart failure (HF), patients with HF are commonly hospitalised due to progressive volume retention with an increase in body weight and the deterioration of symptoms. Arginine vasopressin acts at vasopressin V₂ receptors in the kidney as an antidiuretic. Tolvaptan is an orally-active selective V₂-receptor antagonist. In the Acute and Chronic Therapeutic Impact of a Vasopressin antagonist in Congestive Heart Failure trial of patients hospitalised with HF, tolvaptan 30 mg/day increased urine volume and induced a weight loss of 3.3 kg at discharge (placebo; 1.9 kg). In post hoc analyses, mortality was lower with tolvaptan in patients with renal impairment and severe congestion, compared to placebo. Thus, it seems that tolvaptan is an advancement in the treatment of severely decompensated HF.     

Tolvaptan for the treatment of heart failure: a review of the literature

INTRODUCTION: It has been > 25 years since it was first discovered that arginine vasopressin levels are elevated in heart failure and this elevation is proportional to the severity of heart failure. Tolvaptan is an oral nonpeptide V?-selective antagonist and has been shown to induce free water excretion without increasing urine sodium, an effect termed 'aquaresis'. AREAS COVERED: This paper aims to review the physiology, chemistry, pharmacokinetics, clinical efficacy and safety of tolvaptan in HF. A PubMed literature search was performed using 'tolvaptan' and the MeSH term 'heart failure', yielding 89 references. EXPERT OPINION: Clinical trials conducted in ambulatory and hospitalized patients with HF have found treatment with tolvaptan causes rapid and sustained body weight reductions concurrent with increases in urine output, improves and/or normalizes serum sodium in hyponatremic patients, reduces signs and symptoms of congestion and increases thirst. However, tolvaptan has not been shown to decrease HF re-hospitalization or mortality. As an adjunct to standard therapy, tolvaptan is unique in that it is virtually the only novel agent tested in patients hospitalized for acute heart failure syndrome (AHFS) to reach its primary end point for short-term efficacy without causing deleterious side effects. There is theoretical concern that chronic V? receptor blockade may cause harmful long-term side effects via enhanced V(1a) receptor activation, potentially offsetting any favorable effects on congestion and hyponatremia. The 'vaptan' class of drugs is an active and promising area for clinical investigation and future research is necessary to clarify the therapeutic role of selective and nonselective vasopressin inhibition in chronic HF and AHFS.     

Tolvaptan, an orally active vasopressin V(2)-receptor antagonist - pharmacology and clinical trials

Tolvaptan is an orally effective nonpeptide arginine vasopressin (AVP) V(2)-receptor antagonist synthesized by Otsuka Pharmaceutical Co., Ltd. In in vitro receptor-binding studies, tolvaptan blocked the binding of [(3)H]AVP to human V(2) receptors with 29-fold greater selectivity than that for V(1a) receptors, and showed no inhibition of V(1b) receptors. Tolvaptan inhibited not only the binding of [(3)H]AVP but also the AVP-induced production of cyclic AMP in human V(2)-receptor-expressing HeLa cells. In addition, tolvaptan has no intrinsic V(2) receptor agonistic effect. In in vivo studies, tolvaptan showed marked aquaresis in healthy and diseased animals. In rat models with acute and chronic hyponatremia, tolvaptan improved hyponatremia, resulting in the prevention of death, and improved organ water retention. Tolvaptan reduced cardiac preload without unfavorable effects on renal functions, systemic hemodynamics, or circulating neurohormones in dogs with heart failure (HF). Furthermore, in animal models of human polycystic kidney disease (PKD), tolvaptan showed a decrease in kidney weight as well as in cyst and fibrosis volume. In clinical trials including the "ACTIV in CHF" study, tolvaptan in addition to standard therapy increased fluid loss resulting in decreased body weight, and improved edema and serum sodium without affecting blood pressure, heart rate, or renal functions in patients with HF. In patients with hyponatremia, treatment with tolvaptan without fluid restriction appeared to be more effective than fluid restriction alone at correcting hyponatremia without an increase in adverse events. A phase III trial EVEREST is currently being conducted to evaluate the long-term efficacy and safety of tolvaptan in hospitalized patients with severe HF. In conclusion, tolvaptan offers the possibility of a useful therapy in hyponatremia, congestive heart failure, and various other diseases that are associated with volume overload. Furthermore, tolvaptan is also expected to be effective in the treatment of PKD.     

Brain natriuretic peptide (nesiritide) in the treatment of heart failure

Over the last decade brain natriuretic peptide (BNP) emerged as a cardiac hormone of clinical interest in diagnosis, prognosis and treatment of patients with Heart Failure (HF). The diagnostic potential of BNP is now well established both in patients with suspected HF as well as in patients with asymptomatic left ventricular systolic dysfunction. The prognostic information obtained from BNP levels in HF and acute myocardial infarction patients seems even more promising. Nesiritide is a synthetic peptide, homologous to endogenous BNP. It is a balanced vasodilator with diuretic and natriuretic properties. It decreases the elevated levels of neurohormones resulting from activation of the sympathetic and renin-aldosterone systems in HF. The results of clinical trials involving more than 2000 patients with decompensated HF are now available. In these trials nesiritide was administered by single or repeated bolus injections, as well as by sustained infusions. Nesiritide has been shown to produce a potent, dose-related vasodilator effect that is rapid in onset and sustained during infusion. Balanced vasodilation is reflected by decreases in systemic vascular resistance, pulmonary artery wedge pressure and right atrial pressure. No tachyphylaxis has been observed in these trials. Efficacy of nesiritide in the treatment of decompensated HF has been demonstrated. Trials comparing nesiritide with conventional treatment of decompensated HF showed that nesiritide compares favorably to standard agents. The safety profile has been excellent with a dose-dependent hypotension as the major side effect. Ventricular arrhythmia was not more frequent in patients treated with nesiritide than with placebo. Thus, nesiritide appears to be useful as a first-line agent in the treatment of patients with decompensated HF.     

Potential new drug treatments for congestive heart failure

Introduction: The prevalence of heart failure (HF) has increased globally in recent decades. Advances in our understanding of underlying pathophysiologic mechanisms have given rise to new therapies for treating the growing HF population. Nonetheless, morbidity and mortality associated with HF and its financial implications are daunting. Thus, novel therapies that can improve the natural history of HF patients are urgently needed.

Areas covered: This article reviews new investigational drugs being developed for the treatment of both acute decompensated heart failure (ADHF) and chronic heart failure with reduced ejection fraction (HFrEF). It presents the background of these drugs with a focus on their mechanism of action, their pharmacology, evidence from clinical studies and their potential role in HF management.

Expert opinion: The mortality benefit associated with serelaxin treatment in the RELAX-HF trial is being tested in RELAX-AHF II, while two other drugs, ularitide and TRV027, are also being evaluated in ADHF patients. Two new agents for the treatment of chronic HFrEF, LCZ696 and ivabradine, have been recently been approved for use by the FDA and four novel agents which have shown considerable promise in early studies, omecamtiv mecarbil, vericiguat, finerenone, and neuregulin, are currently being evaluated in late-phase clinical trials.     

Is vasopressin-receptor antagonism an advancement in the treatment of heart failure?

Despite diuretics being used to relieve the fluid retention/congestion associated with heart failure (HF), patients with HF are commonly hospitalised due to progressive volume retention with an increase in body weight and the deterioration of symptoms. Arginine vasopressin acts at vasopressin V2 receptors in the kidney as an antidiuretic. Tolvaptan is an orally-active selective V2-receptor antagonist. In the Acute and Chronic Therapeutic Impact of a Vasopressin antagonist in Congestive Heart Failure trial of patients hospitalised with HF, tolvaptan 30 mg/day increased urine volume and induced a weight loss of 3.3 kg at discharge (placebo; 1.9 kg). In post hoc analyses, mortality was lower with tolvaptan in patients with renal impairment and severe congestion, compared to placebo. Thus, it seems that tolvaptan is an advancement in the treatment of severely decompensated HF.     

Vasopressin receptor antagonists in the management of acute heart failure

Vasopressin is a potent vasoconstrictor and plays a significant role in the regulation of volume homeostasis. Several non-peptide vasopressin receptor antagonists (vaptans) have emerged as promising drugs in the management of acute heart failure. Results of early trials with tolvaptan (selective vasopressin subtype 2 receptor antagonist) and conivaptan (dual vasopressin subtypes 1a and 2 receptor antagonist) have demonstrated improvement in the fluid status, osmotic balance and haemodynamic profile in patients with heart failure presenting with signs and symptoms of decompensation. Nevertheless, their comparative long-term safety and efficacy remains to be determined in large-scale clinical trials.     

Blood Urea Nitrogen/Creatinine Ratio and Response to Tolvaptan in Patients with Decompensated Heart Failure: A Retrospective Analysis

Introduction

Arginine vasopressin-stimulated reabsorption of urea occurs in the collecting duct via increased expression of the urea transporter.

Objective

The aim of this study was to evaluate whether the blood urea nitrogen/creatinine (BUN/Cr) ratio is useful for predicting tolvaptan response in patients with decompensated heart failure (HF).

Methods

Among 71 consecutive patients with HF who received oral tolvaptan between 2010 and 2014, we retrospectively studied 33 patients with decompensated HF without any mechanical circulatory assistance or inotropic support who had already been treated with loop diuretics. A responder to tolvaptan was defined as an individual who experienced a ≥30 % increase in their respective 24-h urine volume.

Results

Among the 33 patients, 21 met the criteria of a responder. The area under the receiver operating characteristic curves of BUN/Cr and BUN were 0.790 and 0.714, respectively, and the respective cut-off values for responders to tolvaptan were 23.8 and 49.0. BUN/Cr and BUN retained their significant relationships with the responder status (odds ratio for BUN/Cr >23.8: 20.9; 95 % confidence interval [CI] 2.7–531.1; p = 0.002; odds ratio for BUN ≥49: 7.7; 95 % CI 1.4–65.8; p = 0.02).

Conclusion

Our results suggest that high BUN/Cr may be a predictor of response to tolvaptan in decompensated HF patients. A prospective study with a large sample size is required to confirm this preliminary finding.

     

Tolvaptan: the evidence for its therapeutic value in acute heart failure syndrome

Introduction:

Acute heart failure syndrome (AHFS) is one of the leading causes of hospital admission in the US. Tolvaptan is a vasopressin V₂ receptor antagonist that blocks the effect of arginine vasopressin (AVP) in reabsorbing water from the collecting ducts of the nephrons in congestive heart failure.

Aims:

To review the evidence for utilizing tolvaptan in the treatment of AHFS.

Evidence review:

Several clinical trials have sought to assess the clinical effects of tolvaptan in heart failure. Compared with placebo, tolvaptan has been shown to reduce bodyweight and improve serum sodium in patients with AHFS without worsening renal function. Tolvaptan appeared to be well tolerated with a good safety profile. It caused a significant reduction in pulmonary capillary wedge pressure compared with placebo, but has yet to demonstrate reversal of cardiac remodeling. A large-scale mortality trial showed no differences in long-term mortality rates between tolvaptan and placebo, although early symptom relief was apparent with tolvaptan and lower diuretic use.

Place in therapy:

Tolvaptan has shown to be safe and effective in treating congestion in AHFS. Free water excretion in fluid-overloaded patients vulnerable to cardiorenal compromise with standard diuretic therapy makes V₂ vasopressin receptor blockade an attractive adjunct to standard medical therapy aimed at reducing congestion in AHFS.     

Tolvaptan: a vasopressin antagonist for the management of euvolemic and hypervolemic hyponatremia

Tolvaptan is a new vasopressin antagonist developed for the treatment of hypervolemic or euvolemic hyponatremia. It has greater affinity for the V₂ receptor than native vasopressin or any other vasopressin antagonist. Blockade of the V₂ receptor induces solute-free water excretion without affecting normal electrolyte excretion. The pharmacokinetics and pharmacodynamics of tolvaptan are suitable for once-daily dosing. Throughout all phases of clinical studies, it was shown to be safe for short- and long-term use. Tolvaptan effectively increases serum sodium levels in patients with heart failure, cirrhosis and syndrome of inappropriate secretion of antidiuretic hormone. In patients hospitalized owing to heart failure, tolvaptan decreased bodyweight, increased urine output and improved dyspnea compared with placebo. However, tolvaptan has not proven to be beneficial for the long-term management of heart failure. Currently, tolvaptan is the only oral agent in its class available in the USA and Europe.     

Present and future pharmacotherapy for heart failure

The pharmacotherapy currently recommended by the American College of Cardiology and the American Heart Association for heart failure (HF) is a diuretic, an angiotensin-converting enzyme inhibitor (ACEI), a β-adrenoceptor antagonist and (usually) digitalis. This current treatment of HF may be improved by optimising the dose of ACEI used, as increasing the dose of lisinopril increases its benefits in HF. Selective angiotensin receptor-1 (AT₁) antagonists are effective alternatives for those who cannot tolerate ACEIs. AT₁ antagonists may also be used in combination with ACEIs, as some studies have shown cumulative benefits for the combination. In addition to being used in Stage IV HF patients, in whom it has a marked benefit, spironolactone should be studied in less severe HF and in the presence of β-blockers. The use of carvedilol, extended-release metoprolol and bisoprolol should be extended to severe HF patients as these agents have been shown to decrease mortality in this group. The ancillary properties of carvedilol, particularly antagonism at prejunctional β-adrenoceptors, may give it additional benefits to selective β₁-adrenoceptor antagonists. Celiprolol and bucindolol are not the β-blockers of choice in HF, as they do not decrease mortality. Although digitalis does not reduce mortality, it remains the only option for a long-term positive inotropic effect, as the long-term use of the phosphodiesterase inhibitors is associated with increased mortality. The calcium sensitising drug levosimendan may be useful in the hospital treatment of decompensated HF to increase cardiac output and improve dyspnoea and fatigue. The antiarrhythmic drug amiodarone should probably be used in patients at high risk of arrhythmic or sudden death, although this treatment may soon be superseded by the more expensive implanted cardioverter defibrillators, which are probably more effective and have fewer side effects. The natriuretic peptide nesiritide has recently been introduced for the hospital treatment of decompensated HF. Novel drugs that may be beneficial in the treatment of HF include the vasopeptidase inhibitors and the selective endothelin-A receptor antagonists but these require much more investigation. However, disappointing results have been obtained in a large clinical trial of the tumour necrosis factor α antagonist etanercept, where no likelihood of a difference between placebo and etanercept was observed. Small clinical trials with recombinant growth hormone to thicken ventricles in dilated cardiomyopathy have given variable results.     

B-type natriuretic peptide for diagnosis and therapy

Brain natriuretic peptide (BNP) plays an important role in cardiovascular homeostasis. Plasma BNP increases markedly in left ventricular dysfunction from several causes, and its levels in heart failure (HF) correlate with symptoms severity. BNP has recently emerged as a potentially important clinical marker for the diagnosis of HF in patients with unexplained dyspnea. Other clinical applications of BNP, such as screening for asymptomatic ventricular dysfunction, establishing the prognosis or guiding the titration of drug therapy, are under investigation and have not yet been sufficiently validated for widespread clinical use. Laboratory-based and point-of-care analyses are available for BNP and N-terminal proBNP as fully-automated immunoassays. Several patented inventions and reagents for the diagnosis of various heart pathologies provide helpful information, particularly in conjunction with other clinical tests. They also have prognostic value for future cardiovascular events. Patents owned by Scios Inc. recommended recombinant BNP for managing acute decompensated HF. However, this treatment apparently has safety problems and no proven clinical advantage over existing treatments in terms of improved survival and prevention of subsequent hospitalizations.     

Device Therapy for Heart Failure

Surgical approaches to heart failure (HF) management have become a necessary strategy in response to a waiting list that is expanding in the face of a limited supply of organ donors. Multiple studies have supported the safety and efficacy of device-based therapy. Among the device-based therapy options, ventricular assist devices (VADs) represent an alternative to heart transplantation with the capability to function as short-term support, bridge-to-transplantation or recovery and as long-term support. VAD support may be considered in those with refractory cardiogenic shock or those with decompensated chronic HF that is unresponsive to maximized medical therapy. Composite scoring scales may be used to risk-stratify patients using clinical and laboratory values to allow more systematic patient selection. As the pursuit for a perfect device continues, so does the search for the best objective index to guide referral. Technologic advances will enhance device performance and extend VAD use into community practice. This discussion aims to highlight criteria for candidate selection and referral for VAD implantation.     

Present and future pharmacotherapy for heart failure

The pharmacotherapy currently recommended by the American College of Cardiology and the American Heart Association for heart failure (HF) is a diuretic, an angiotensin-converting enzyme inhibitor (ACEI), a beta-adrenoceptor antagonist and (usually) digitalis. This current treatment of HF may be improved by optimising the dose of ACEI used, as increasing the dose of lisinopril increases its benefits in HF. Selective angiotensin receptor-1 (AT(1)) antagonists are effective alternatives for those who cannot tolerate ACEIs. AT(1) antagonists may also be used in combination with ACEIs, as some studies have shown cumulative benefits for the combination. In addition to being used in Stage IV HF patients, in whom it has a marked benefit, spironolactone should be studied in less severe HF and in the presence of beta-blockers. The use of carvedilol, extended-release metoprolol and bisoprolol should be extended to severe HF patients as these agents have been shown to decrease mortality in this group. The ancillary properties of carvedilol, particularly antagonism at prejunctional beta -adrenoceptors, may give it additional benefits to selective beta(1)-adrenoceptor antagonists. Celiprolol and bucindolol are not the beta-blockers of choice in HF, as they do not decrease mortality. Although digitalis does not reduce mortality, it remains the only option for a long-term positive inotropic effect, as the long-term use of the phosphodiesterase inhibitors is associated with increased mortality. The calcium sensitising drug levosimendan may be useful in the hospital treatment of decompensated HF to increase cardiac output and improve dyspnoea and fatigue. The antiarrhythmic drug amiodarone should probably be used in patients at high risk of arrhythmic or sudden death, although this treatment may soon be superseded by the more expensive implanted cardioverter defibrillators, which are probably more effective and have fewer side effects. The natriuretic peptide nesiritide has recently been introduced for the hospital treatment of decompensated HF. Novel drugs that may be beneficial in the treatment of HF include the vasopeptidase inhibitors and the selective endothelin-A receptor antagonists but these require much more investigation. However, disappointing results have been obtained in a large clinical trial of the tumour necrosis factor alpha antagonist etanercept, where no likelihood of a difference between placebo and etanercept was observed. Small clinical trials with recombinant growth hormone to thicken ventricles in dilated cardiomyopathy have given variable results.     

Newest additions to heart failure treatment

Introduction: Despite the improvement in heart failure (HF) therapy in the last 30 years, this condition remains a major public health concern with high hospitalization and mortality rates, and related costs. Recently, new pharmacological approaches are under evaluation.

Areas covered: For chronic HF with reduced ejection fraction (EF) direct renin inhibitors, neprilysin-angiotensin II receptor inhibitors and aldosterone synthase inhibitors have been tested. For HF with preserved EF, no therapy has been demonstrated up to now to be able to improve patients’ outcomes and it remains a substantial unmet need. In acute HF (AHF) new inotropes and vasodilators have been developed and are currently investigated in trials. In this review, mechanism of action and clinical efficacy of new pharmacological approaches on acute and chronic HF will be discussed.

Expert opinion: In patients with HF, some unmet needs remain to be challenged in the near future. For patients with chronic HF, the management of comorbidities, a better definition and treatment of patients with preserved EF are the major issues to be solved. The treatment of patients admitted for AHF is even more compelling. Several hypotheses of research focused on these issues are tested in ongoing trials.     

Potential Mechanisms of Benefit with Thalidomide in Chronic Heart Failure

This review considers the recent clinical and relevant preclinical evidence that thalidomide may have therapeutic benefit in chronic heart failure (HF), and considers some of the mechanisms by which thalidomide may elicit potentially beneficial effects. Persistent inflammation, involving increased levels of inflammatory cytokines, seems to play a pathogenic role in chronic HF by influencing heart contractility, inducing matrix degradation and fibrosis, and promoting apoptosis, contributing to myocardial remodeling. On the basis of these issues, immunomodulating therapy has emerged as an option in the management of chronic HF. Failure of anti-tumor necrosis factor (TNF) therapy has lead to further interest in a more general immunomodulatory approach, directed against the imbalanced cytokine network rather than at one particular cytokine.Some recent studies suggest that thalidomide, a glutamic acid derivative with proposed antiangiogenic, anti-inflammatory, and immunomodulatory properties, should be added to the list of potential immunomodulating agents in chronic HF. Thus, in a recent double-blind, placebo-controlled study in patients with chronic HF, thalidomide was found to significantly improve left ventricular ejection fraction. Although thalidomide has been regarded as an anti-TNF drug, it was found to increase plasma levels of TNFalpha in a placebo-controlled study in patients with HF, suggesting that other mechanisms may contribute to its beneficial effects. Such mechanisms could involve inhibition of neutrophils, matrix stabilizing, and antifibrotic effects, as well as a thalidomide-mediated decrease in the heart rate. However, our knowledge of the mechanisms of action of this drug is still scarce and will have to be further examined in forthcoming studies. Such studies should include experiments in animal models of HF as well as further preclinical trials, attempting to identify the potential mechanisms by which thalidomide may be beneficial in human HF.     

New developments in the use of β-blockers for the management of heart failure

Chronic heart failure (HF) has become a significant healthcare problem in the US. The number of new cases per year continues to grow steadily due to an ageing population and improved survival from acute coronary syndromes. As a consequence, the management of HF patients is of great importance. Effective management of HF includes stabilising the patient and improving the clinical symptoms associated with HF. Patients with HF have increased sympathetic nervous system activity that contributes to impaired cardiovascular function over time and subsequently results in death. β-blockers prevent such impairment through inhibition of the sympathetic nervous system neurohormonal pathway. Numerous clinical trials conducted over the past decade have demonstrated that β-blockers, in conjunction with angiotensin-converting enzyme inhibitors, are not only effective but are superior to other medical interventions for the treatment of HF. The standard of care for patients with HF now includes β-blockers as well as ACE inhibitors.     

New developments in the use of beta-blockers for the management of heart failure

Chronic heart failure (HF) has become a significant healthcare problem in the US. The number of new cases per year continues to grow steadily due to an ageing population and improved survival from acute coronary syndromes. As a consequence, the management of HF patients is of great importance. Effective management of HF includes stabilising the patient and improving the clinical symptoms associated with HF. Patients with HF have increased sympathetic nervous system activity that contributes to impaired cardiovascular function over time and subsequently results in death. beta-blockers prevent such impairment through inhibition of the sympathetic nervous system neurohormonal pathway. Numerous clinical trials conducted over the past decade have demonstrated that beta-blockers, in conjunction with angiotensin-converting enzyme inhibitors, are not only effective but are superior to other medical interventions for the treatment of HF. The standard of care for patients with HF now includes beta-blockers as well as ACE inhibitors.