A vasopressin receptor antagonist (VPA-985) improves serum sodium concentration in patients with hyponatremia: a multicenter, randomized, placebo-controlled trial

Clinical Significance and Management of Hyponatremia in Liver Cirrhosis

The overall prevalence of hyponatremia in cirrhotics is around 50%. Hypovolemic hyponatremia is a result of excessive fluid loss caused mostly by diuretic treatment or diarrhea. More common is hypervolemic hyponatremia, which results from excessive activation of water and sodium-retaining mechanisms caused by effective arterial hypovolemia. This review focuses on the associations of hyponatremia with clinical outcomes and reviews the available data on its management. Hyponatremia is a strong predictor of mortality and is also associated with an increased probability of hepatorenal syndrome, disturbance of consciousness, infections, and unfavorable post-transplant outcomes. In the management of hyponatremia, it is crucial to distinguish between hypovolemic and hypervolemic hyponatremia. The treatment of hypervolemic hyponatremia should be started only in symptomatic patients. The cessation of the treatment with traditional diuretics and fluid restriction may prevent further decrease in natremia. Pharmacological treatment is directed towards cirrhosis itself, precipitating factor, or hyponatremia directly. Currently, only albumin infusions can be recommended routinely. Other possibilities, such as vaptans, splanchnic vasoconstrictors, niravoline, or osmotic diuretics, are restricted to specific use cases (e.g., imminent liver transplantation) or need more research to determine their efficacy. We tried to summarize the management of hyponatremia into a concise flowchart.

Korean Society of Nephrology 2022 recommendations on controversial issues in diagnosis and management of hyponatremia

The Korean Society for Electrolyte and Blood Pressure Research, in collaboration with the Korean Society of Nephrology, has published a clinical practice guideline (CPG) document for hyponatremia treatment. The document is based on an extensive evidence-based review of the diagnosis, evaluation, and treatment of hyponatremia with the multidisciplinary participation of representative experts in hyponatremia with methodologist support for guideline development. This CPG consists of 12 recommendations (two for diagnosis, eight for treatment, and two for special situations) based on eight detailed topics and nine key questions. Each recommendation begins with statements graded by the strength of the recommendations and the quality of the evidence. Each statement is followed by rationale supporting the recommendations. The committee issued conditional recommendations in favor of rapid intermittent bolus administration of hypertonic saline in severe hyponatremia, the use of vasopressin receptor antagonists in heart failure with hypervolemic hyponatremia, and syndrome of inappropriate antidiuresis with moderate to severe hyponatremia, the individualization of desmopressin use, and strong recommendation on the administration of isotonic fluids as maintenance fluid therapy in hospitalized pediatric patients. We hope that this CPG will provide useful recommendations in practice, with the aim of providing clinical support for shared decision-making to improve patient outcomes.

Korean Society of Nephrology 2022 Recommendations on controversial issues in diagnosis and management of hyponatremia

The Korean Society for Electrolyte and Blood Pressure Research, in collaboration with the Korean Society of Nephrology, has published a clinical practice guideline (CPG) document for hyponatremia treatment. The document is based on an extensive evidence-based review of the diagnosis, evaluation, and treatment of hyponatremia with the multidisciplinary participation of representative experts in hyponatremia with methodologist support for guideline development. This CPG consists of 12 recommendations (two for diagnosis, eight for treatment, and two for special situations) based on eight detailed topics and nine key questions. Each recommendation begins with statements graded by the strength of the recommendations and the quality of the evidence. Each statement is followed by rationale supporting the recommendations. The committee issued conditional recommendations in favor of rapid intermittent bolus administration of hypertonic saline in severe hyponatremia, the use of vasopressin receptor antagonists in heart failure with hypervolemic hyponatremia, and syndrome of inappropriate antidiuresis with moderate to severe hyponatremia, the individualization of desmopressin use, and strong recommendation on the administration of isotonic fluids as maintenance fluid therapy in hospitalized pediatric patients. We hope that this CPG will provide useful recommendations in practice, with the aim of providing clinical support for shared decision-making to improve patient outcomes.

Part 1: Disease of the Heart and Liver: A Relationship That Cuts Both Ways

The heart and the liver display multifaceted, complex interactions that can be divided into cardiac effects of liver disease, hepatic effects of heart disease, and disease processes affecting both organs. In part 1 of this 2 part series, we discuss how acute and chronic heart failure can have devastating effects on the liver, such as acute cardiogenic liver injury and congestive hepatopathy. On the other hand, primary liver disease, such as cirrhosis, can lead to a plethora of cardiac insults representative in cirrhotic cardiomyopathy as systolic dysfunction, diastolic dysfunction, and electrophysiological disturbances. Nonalcoholic fatty liver disease has long been associated with cardiovascular events that increase mortality. The management of both disease processes changes when the other organ system becomes involved. This consideration is important with regard to a variety of interventions, most notably transplantation of either organ, as risk of complications dramatically rises in the setting of both heart and liver disease (discussed in part 2). As our understanding of the intricate communication between the heart and liver continues to expand so does our management.

Risks of vaptans in hypernatremia and serum sodium overcorrection: A systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

Serum sodium overcorrection and hypernatremia are significant health risks. We conducted a systematic review and meta-analysis to evaluate the risks of vaptans in hypernatremia and serum sodium overcorrection.

METHODS

We searched PubMed, Embase, and CENTRAL for randomised controlled trials. We included studies comparing vaptans and placebo with data on hypernatremia and serum sodium overcorrection. The study quality was assessed using the Cochrane Collaboration's risk-of-bias assessment tool. Fixed-effect model meta-analysis was used to pool the data. Different analyses were performed to ensure the accuracy of the results.

RESULTS

Twenty-eight studies were included in the meta-analysis of hypernatremia incidence. Treatment with vaptans resulted in a higher risk of hypernatremia than placebo (3.8% vs 1.0%, odds ratio [OR] 2.69; 95% confidence interval [CI] 1.97-3.68). The subgroup with baseline hyponatremia had a lower risk of hypernatremia incidence; however, the use of loop diuretics increased the risk. Fourteen studies were included in the analysis of the incidence of serum sodium overcorrection. A higher risk of serum sodium overcorrection was found in using vaptans vs placebo (4.4% vs 1.4%; OR 2.26; 95% CI 1.32-3.86).

CONCLUSION

Vaptans showed higher risks in the incidence of hypernatremia and serum sodium overcorrection than placebo. In addition, combination with loop diuretics increased the risk of hypernatremia. The risk of serum sodium overcorrection should be concerned in patients with hyponatremia and normal serum sodium equally. Using a low dose of vaptans can reduce both risks.

Validation of the Model for End-stage Liver Disease sodium (MELD-Na) score in the Eurotransplant region

The MELD score is used in the Eurotransplant (ET) region to allocate liver grafts. Hyponatremia in cirrhotic patients is an important predictor of death but is not incorporated in MELD. This study investigated the performance of the MELD-Na score for the ET region. All adult patients with chronic liver disease on the ET liver transplantation waiting list (WL) allocated through lab MELD scores were included. The MELD-corrected effect of serum sodium (Na) concentration at listing on the 90-day WL mortality was calculated using Cox regression. The MELD-Na performance was assessed with c-indices, calibration per decile and Brier scores. The reclassification from MELD to MELD-Na score was calculated to estimate the impact of MELD-Na-based allocation in the ET region. For the 5223 included patients, the risk of 90-day WL death was 2.9 times higher for hyponatremic patients. The MELD-Na had a significantly higher c-index of 0.847 (SE 0.007) and more accurate 90-day mortality prediction compared to MELD (Brier score of 0.059 vs 0.061). It was estimated that using MELD-Na would reduce WL mortality by 4.9%. The MELD-Na score yielded improved prediction of 90-day WL mortality in the ET region and using MELD-Na for liver allocation will very likely reduce WL mortality.

Impact of Vaptans on Clinical Outcomes in Cirrhosis Patients: A Meta-Analysis of Randomized Controlled Trials

Background: Vaptans have been confirmed to mobilize ascites and improve hyponatremia in cirrhosis patients. However, the effects of vaptans on all-cause mortality, ascites-related complications, and adverse events in cirrhosis patients have not been fully determined.

Objectives: To systematically evaluate the impact of vaptans on the clinical outcomes in patients with cirrhosis.

Materials and Methods: A systematic review and meta-analysis was performed. The PubMed, Embase, and Cochrane’s Library electronic databases were systematically searched for randomized controlled trials (RCTs) investigating the clinical efficacy of vaptans in cirrhosis patients. The results were pooled with a random-effect model.

Results: Eighteen RCTs containing 3,059 cirrhosis patients with ascites and/or hyponatremia were included. Meta-analysis showed that vaptans did not significantly affect the risk of all-cause mortality (RR: 1.02, 95% CI: 0.87 to 1.08, p = 0.83; I² = 2%), consistent with studies with short-term (< 26 weeks) and long-term (≥ 26 weeks) follow-up durations. Additionally, vaptans did not affect the incidence of variceal bleeding (RR: 0.96, p = 0.86), showed a trend of reduced incidence of hepatic encephalopathy (RR: 0.86, p = 0.09), significantly reduced the incidence of spontaneous bacterial peritonitis (RR: 0.75, p = 0.03), but did not significantly affect the risk of hepatorenal syndrome or renal failure (RR: 1.09, p = 0.36). Vaptans did not affect the incidence of adverse events in cirrhosis patients.

Discussion: Treatment with vaptans is not associated with improved survival in cirrhosis patients, although it may reduce the risk of hepatic encephalopathy and spontaneous bacterial peritonitis in these patients. The limitations of the current study include limited number of available studies, small sample sizes of the included studies, variations of baseline patient characteristics, and differences in the dose and duration of vaptans.

Management Strategies and Outcomes for Hyponatremia in Cirrhosis in the Hyponatremia Registry

AIM

Treatment practices and effectiveness in cirrhotic patients with hyponatremia (HN) in the HN Registry were assessed.

METHODS

Characteristics, treatments, and outcomes were compared between patients with HN at admission and during hospitalization. For HN at admission, serum sodium concentration [Na] response was analyzed until correction to > 130 mmol/L, switch to secondary therapy, or discharge or death with sodium ≤ 130 mmol/L.

RESULTS

Patients with HN at admission had a lower [Na] and shorter length of stay (LOS) than those who developed HN (P < 0.001). Most common initial treatments were isotonic saline (NS, 36%), fluid restriction (FR, 33%), and no specific therapy (NST, 20%). Baseline [Na] was higher in patients treated with NST, FR, or NS versus hypertonic saline (HS) and tolvaptan (Tol) (P < 0.05). Treatment success occurred in 39%, 39%, 52%, 78%, and 81% of patients with NST, FR, NS, HS, and Tol, respectively. Relapse occurred in 55% after correction and was associated with increased LOS (9 versus 6 days, P < 0.001). 34% admitted with HN were discharged with HN corrected.

CONCLUSIONS

Treatment approaches for HN were variable and frequently ineffective. Success was greatest with HS and Tol. Relapse of HN is associated with increased LOS.

Correction of Hyponatremia May Be a Treatment Stratification Biomarker: A Two-Stage Systematic Review and Meta-Analysis

Changes in serum sodium concentration ([Na⁺]_serum) can permit evaluation of the treatment effect of vasopressin antagonists (vaptans) in patients with worsening heart failure (HF) or cirrhotic ascites; that is, they may act as a treatment stratification biomarker. A two-stage systematic review and meta-analysis were carried out and contextualized by experts in fluid resuscitation and translational pharmacology (registration ID in the International Prospective Register of Systematic Reviews (PROSPERO): CRD42017051440). Meta-analysis of aggregated dichotomous outcomes was performed. Pooled estimates for correction of hyponatremia (normalization or an increase in [Na⁺]_serum of at least 3–5 mEq/L) under treatment with vaptans (Stage 1) and for clinical outcomes in both worsening HF (rehospitalization and/or death) and cirrhotic ascites (ascites worsening) when correction of hyponatremia is achieved (Stage 2) were calculated. The body of evidence was assessed. Correction of hyponatremia was achieved under vaptans (odds ratio (OR)/95% confidence interval (95% CI)/I²/number of studies (n): 7.48/4.95–11.30/58%/15). Clinical outcomes in both worsening HF and cirrhotic ascites improved when correction of hyponatremia was achieved (OR/95% CI/I²/n: 0.51/0.26–0.99/52%/3). Despite the appropriateness of the study design, however, there are too few trials to consider that correction of hyponatremia is a treatment stratification biomarker. Patients with worsening HF or with cirrhotic ascites needing treatment with vaptans, have better clinical outcomes when correction of hyponatremia is achieved. However, the evidence base needs to be enlarged to propose formally correction of hyponatremia as a new treatment stratification biomarker. Markers for use with drugs are needed to improve outcomes related to the use of medicines.

The Impact of Albumin Use on Resolution of Hyponatremia in Hospitalized Patients With Cirrhosis

OBJECTIVES

Hyponatremia is associated with poor outcomes in cirrhosis independent of MELD. While intravenous albumin has been used in small series, its role in hyponatremia is unclear. The aim of this study is to determine the effect of albumin therapy on hyponatremia.

METHODS

Hospitalized cirrhotic patients included in the NACSELD (North American Consortium for End-Stage Liver Disease) cohort with hyponatremia (Na <130mmol/L) were divided into those receiving intravenous albumin or not. Determinants of hyponatremia resolution (Na ≥135 meq/L) and 30-day survival were analyzed using regression and ANCOVA models.

RESULTS

Overall, 2435 patients, of whom 1126 had admission hyponatremia, were included. Of these, 777 received 225 (IQR 100,400) g of albumin, while 349 did not. Patients given albumin had a higher admission MELD score, and serum creatinine and lower admission Na and mean arterial pressure (MAP). However they experienced a higher maximum Na and hyponatremia resolution (69% vs 61%, p = 0.008) compared to those who did not. On regression, delta Na was independently associated with admission creatinine, MAP and albumin use. On ANCOVA with logistic regression, there was a significant difference in hyponatremia resolution between those who did or did not receive albumin, even after adjustment for admission Na and GFR (85.41% vs 44.78%, p = 0.0057, OR: 1.50 95% CI: 1.13-2.00). Independent predictors of 30-day survival were hyponatremia resolution, age, ACLF, and admission GFR.

CONCLUSION

Hospitalized patients with cirrhosis and hyponatremia who received intravenous albumin had a higher rate of hyponatremia resolution independent of renal function and baseline sodium levels, which was in turn associated with a better 30-day survival.

[Hyponatremia in Liver Cirrhosis]

Hyponatremia is a commonly observed complication that is related to hypoalbuminemia and portal hypertension in patients with advanced liver cirrhosis. Hyponatremia in patients with liver cirrhosis is mostly dilutional hyponatremia and is defined when the serum sodium concentration is below 130 meq/L. The risk of complications increases significantly in cirrhotic patients with hyponatremia, which includes spontaneous bacterial peritonitis, hepatorenal syndrome, and hepatic encephalopathy. In addition, hyponatremia is associated with increased morbidity and mortality in patients with cirrhosis, and is an important prognostic factor before and after liver transplantation. The conventional therapies of hyponatremia are albumin infusion, fluid restriction and loop diuretics, but these are frequently ineffective. This review investigates the pathophysiology and various therapeutic modalities, including selective vasopressin receptor antagonists, for the management of hyponatremia in patients with liver cirrhosis.

Interventions for chronic non-hypovolaemic hypotonic hyponatraemia

BACKGROUND

Chronic (present > 48 hours) non-hypovolaemic hyponatraemia occurs frequently, can be caused by various conditions, and is associated with shorter survival and longer hospital stays. Many treatments, such as fluid restriction or vasopressin receptor antagonists can be used to improve the hyponatraemia, but whether that translates into improved patient-important outcomes is less certain.

OBJECTIVES

This review aimed to 1) look at the benefits and harms of interventions for chronic non-hypovolaemic hypotonic hyponatraemia when compared with placebo, no treatment or head-to-head; and 2) determine if benefits and harms vary in absolute or relative terms dependent on the specific compound within a drug class, on the dosage used, or the underlying disorder causing the hyponatraemia.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 1 December 2017 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov. We also screened the reference lists of potentially relevant studies, contacted authors, and screened the websites of regulatory agencies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs that compared the effects of any intervention with placebo, no treatment, standard care, or any other intervention in patients with chronic non-hypovolaemic hypotonic hyponatraemia. We also included subgroups with hyponatraemia from studies with broader inclusion criteria (e.g. people with chronic heart failure or people with cirrhosis with or without hyponatraemia), provided we could obtain outcomes for participants with hyponatraemia from the report or the study authors.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed risk of bias. We expressed treatment effects as mean difference (MD) for continuous outcomes (health-related quality of life, length of hospital stay, change from baseline in serum sodium concentration, cognitive function), and risk ratio (RR) for dichotomous outcomes (death, response and rapid increase in serum sodium concentration, hypernatraemia, polyuria, hypotension, acute kidney injury, liver function abnormalities) together with 95% confidence intervals (CI).

MAIN RESULTS

We identified 35 studies, enrolling 3429 participants. Twenty-eight studies (3189 participants) compared a vasopressin receptor antagonist versus placebo, usual care, no treatment, or fluid restriction. In adults with chronic, non-hypovolaemic hypotonic hyponatraemia, vasopressin receptor antagonists have uncertain effects on death at six months (15 studies, 2330 participants: RR 1.11, 95% CI 0.92 to 1.33) due to risk of selective reporting and serious imprecision; and on health-related quality of life because results are at serious risk of performance, selective reporting and attrition bias, and suffer from indirectness related to the validity of the Short Form Health Survey (SF-12) in the setting of hyponatraemia. Vasopressin receptor antagonists may reduce hospital stay (low certainty evidence due to risk of performance bias and imprecision) (3 studies, 610 participants: MD -1.63 days, 95% CI -2.96 to -0.30), and may make little or no difference to cognitive function (low certainty evidence due to indirectness and imprecision). Vasopressin receptor antagonists probably increase the intermediate outcome of serum sodium concentration (21 studies, 2641 participants: MD 4.17 mmol/L, 95% CI 3.18 to 5.16), corresponding to two and a half as many people having a 5 to 6 mmol/L increase in sodium concentration compared with placebo at 4 to 180 days (moderate certainty evidence due to risk of attrition bias) (18 studies, 2014 participants: RR 2.49, 95% CI 1.95 to 3.18). But they probably also increase the risk of rapid serum sodium correction - most commonly defined as > 12 mmol/L/d (moderate certainty evidence due to indirectness) (14 studies, 2058 participants: RR 1.67, 95% CI 1.16 to 2.40) and commonly cause side-effects such as thirst (13 studies, 1666 participants: OR 2.77, 95% CI 1.80 to 4.27) and polyuria (6 studies, 1272 participants): RR 4.69, 95% CI 1.59 to 13.85) (high certainty evidence). The potential for liver toxicity remains uncertain due to large imprecision. Effects were generally consistent across the different agents, suggesting class effect.Data for other interventions such as fluid restriction, urea, mannitol, loop diuretics, corticosteroids, demeclocycline, lithium and phenytoin were largely absent.

AUTHORS' CONCLUSIONS

In people with chronic hyponatraemia, vasopressin receptor antagonists modestly raise serum sodium concentration at the cost of a 3% increased risk of it being rapid. To date there is very low certainty evidence for patient-important outcomes; the effects on mortality and health-related quality of life are unclear and do not rule out appreciable benefit or harm; there does not appear to be an important effect on cognitive function, but hospital stay may be slightly shorter, although available data are limited. Treatment decisions must weigh the value of an increase in serum sodium concentration against its short-term risks and unknown effects on patient-important outcomes. Evidence for other treatments is largely absent.Further studies assessing standard treatments such as fluid restriction or urea against placebo and one-another would inform practice and are warranted. Given the limited available evidence for patient-important outcomes, any study should include these outcomes in a standardised manner.

Electrolyte and Acid-Base Disturbances in End-Stage Liver Disease: A Physiopathological Approach

Electrolyte and acid-base disturbances are frequent in patients with end-stage liver disease; the underlying physiopathological mechanisms are often complex and represent a diagnostic and therapeutic challenge to the physician. Usually, these disorders do not develop in compensated cirrhotic patients, but with the onset of the classic complications of cirrhosis such as ascites, renal failure, spontaneous bacterial peritonitis and variceal bleeding, multiple electrolyte, and acid-base disturbances emerge. Hyponatremia parallels ascites formation and is a well-known trigger of hepatic encephalopathy; its management in this particular population poses a risky challenge due to the high susceptibility of cirrhotic patients to osmotic demyelination. Hypokalemia is common in the setting of cirrhosis: multiple potassium wasting mechanisms both inherent to the disease and resulting from its management make these patients particularly susceptible to potassium depletion even in the setting of normokalemia. Acid-base disturbances range from classical respiratory alkalosis to high anion gap metabolic acidosis, almost comprising the full acid-base spectrum. Because most electrolyte and acid-base disturbances are managed in terms of their underlying trigger factors, a systematic physiopathological approach to their diagnosis and treatment is required.

A systematic review of known interventions for the treatment of chronic nonhypovolaemic hypotonic hyponatraemia and a meta-analysis of the vaptans

International and national guidelines on the treatment of chronic nonhypovolaemic hypotonic hyponatraemia differ; therefore, we have undertaken this systematic review and meta-analysis to investigate the efficacy and safety of interventions for the treatment of chronic nonhypovolaemic hypotonic hyponatraemia. Following registration of the review protocol with PROSPERO, systematic literature searches were conducted to identify randomized and quasi-randomized controlled trials assessing any degree of fluid restriction or any drug treatment with the aim of increasing serum sodium concentration in patients with chronic nonhypovolaemic hypotonic hyponatraemia. Where appropriate, outcome data were synthesized in a meta-analysis. A total of 45 716 bibliographic records were identified from the searches and 18 trials (assessing conivaptan, lixivaptan, tolvaptan and satavaptan) met the eligibility criteria. Results suggest that all four vasopressin receptor agonists ("vaptans") significantly improve serum sodium concentration. Lixivaptan, satavaptan and tolvaptan were associated with greater rates of response versus placebo. There was no evidence of a difference between each of the vaptans compared with placebo for mortality, discontinuation and rates of hypernatraemia. No RCT evidence of treatments other than the vaptans for hyponatraemia such as oral urea, salt tablets, mannitol, loop diuretics demeclocycline or lithium was identified. Vaptans demonstrated superiority over placebo for outcomes relating to serum sodium correction. Few trials documented the potential benefit of vaptans on change in health-related quality of life as a result of treatment. There was also a lack of high-quality RCT evidence on the comparative efficacy of the vaptans and other treatment strategies for the treatment of chronic nonhypovolaemic hypotonic hyponatraemia.

Ascites, refractory ascites and hyponatremia in cirrhosis

Ascites is the most common complication related to cirrhosis and is associated with increased morbidity and mortality. Ascites is a consequence of the loss of compensatory mechanisms to maintain the overall effective arterial blood volume due to worsening splanchnic arterial vasodilation as a result of clinically significant portal hypertension. In order to maintain effective arterial blood volume, vasoconstrictor and antinatriuretic pathways are activated, which increase overall sodium and fluid retention. As a result of progressive splanchnic arterial vasodilation, intestinal capillary pressure increases and results in the formation of protein-poor fluid within the abdominal cavity due to increased capillary permeability from the hepatic sinusoidal hypertension. In some patients, the fluid can translocate across diaphragmatic fenestrations into the pleural space, leading to hepatic hydrothorax. In addition, infectious complications such as spontaneous bacterial peritonitis can occur. Eventually, as the liver disease progresses related to higher portal pressures, loss of a compensatory cardiac output and further splanchnic vasodilation, kidney function becomes compromised from worsening renal vasoconstriction as well as the development of impaired solute-free water excretion and severe sodium retention. These mechanisms then translate into significant clinical complications, such as refractory ascites, hepatorenal syndrome and hyponatremia, and all are linked to increased short-term mortality. Currently, liver transplantation is the only curative option for this spectrum of clinical manifestations but ongoing research has led to further insight on alternative approaches. This review will further explore the current understanding on the pathophysiology and management of ascites as well as expand on two advanced clinical consequences of advanced liver disease, refractory ascites and hyponatremia.

Midodrine and tolvaptan in patients with cirrhosis and refractory or recurrent ascites: a randomised pilot study

BACKGROUND

Splanchnic arterial vasodilatation and subsequent sodium and water retention play an important role in cirrhotic ascites. Midodrine and tolvaptan have been used separately in these patients. However, there are no reports on the use of combination of midodrine and tolvaptan in the control of ascites. The aim of this study was to evaluate the safety and efficacy of midodrine, tolvaptan and their combination in control of refractory or recurrent ascites in cirrhotics.

METHODS

Fifty cirrhotic patients with refractory or recurrent ascites were randomised to receive midodrine (n=13), tolvaptan (n=12) or both (n=13) plus standard medical therapy (SMT) or SMT alone (n=12).

RESULTS

A significant increase in urinary volume and urinary sodium at 1 and 3 months (P<.05) was observed in all groups except SMT. There was no worsening of renal or hepatic function in any group. There was deterioration of model for end-stage liver disease (MELD) in SMT. Midodrine as well as combination of midodrine and tolvaptan but not tolvaptan alone was superior to SMT in control of ascites at 3 months (P<.05). The combination therapy was also superior to midodrine in the control of ascites at 1 month. The morbidity and mortality were similar in all the groups except SMT.

CONCLUSIONS

The results of this pilot study suggest that midodrine and combination with tolvaptan better controls ascites without any renal or hepatic dysfunction. The combination therapy rapidly controls ascites as compared to midodrine or tolvaptan alone.

Efficacy and Safety of Vasopressin Receptor Antagonists for Euvolemic or Hypervolemic Hyponatremia: A Meta-Analysis

Hyponatremia, defined as a nonartifactual serum sodium level <135 mmol/L, is the most common fluid and electrolyte abnormality in clinical practice. Traditional managements (fluid restriction, hypertonic saline and loop diuretics, etc.) are difficult to maintain or ineffective. Recently, vasopressin receptor antagonists (VRAs) have shown promise for the treatment of hyponatremia. We aimed to conduct a meta-analysis to evaluate the efficacy and safety of VRAs in patients with euvolemic or hypervolemic hyponatremia. We searched Pubmed, Cochrane Library, Web of Science and Springer, etc. (latest search on June 4, 2015) for English publications with randomized controlled trials. Two authors independently screened the citations and extracted data. We calculated pooled relative risk (RR), risk difference (RD), weighted mean difference (WMD) or standard mean difference (SMD), and 95% confidence intervals (CIs) by using random and fixed effect models. We collected data from 18 trials involving 1806 patients. Both random and fixed effect meta-analyses showed that VRAs significantly increased the net change of serum sodium concentration (WMD(random) = 4.89 mEq/L, 95%CIs = 4.35-5.43 and WMD(fixed) = 4.70 mEq/L, 95%CIs = 4.45-4.95), response rate (RR(random )= 2.77, 95%CIs = 2.29-3.36 and RR(fixed) = 2.95, 95%CIs = 2.56-3.41), and 24-hour urine output (SMD(random) = 0.82, 95%CIs = 0.65-1.00 and SMD(fixed) = 0.79, 95%CIs = 0.66-0.93) compared to placebo. Furthermore, VRAs significantly decreased body weight (WMD(random) = -0.87 kg, 95%CIs = -1.24 to -0.49 and WMD(fixed) = -0.91 kg, 95%CIs = -1.22 to -0.59). In terms of safety, rates of drug-related adverse events (AEs), rapid sodium level correction, constipation, dry mouth, thirst, and phlebitis in the VRA-treated group were greater than those in control group. However, there was no difference in the total number of AEs, discontinuations due to AEs, serious AEs, death, headache, hypotension, nausea, anemia, hypernatremia, urinary tract infection, renal failure, pyrexia, upper gastrointestinal bleeding, diarrhea, vomiting, peripheral edema, and dizziness between the 2 groups. Random effect meta-analyses showed that post treatment urine osmolality, supine systolic blood pressure, and diastolic blood pressure were lowered (WMD(random) = -233.07 mOsmol/kg, 95%CIs = -298.20-147.94; WMD(random) = -6.11 mmHg, 95%CIs = -9.810 to -2.41; WMD(random )= -2.59 mmHg, 95%CIs = -4.06 to -1.11, respectively), but serum osmolality was increased (WMD(random) = 9.29 mOsmol/kg, 95%CIs = 5.56-13.03). There was no significant change from baseline in serum potassium concentration between the 2 groups (WMD(fixed) = 0.00 mmHg, 95%CIs = -0.07-0.06). VRAs are relatively effective and safe for the treatment of hypervolemic and euvolemic hyponatremia.

Do vasopressin V2 receptor antagonists benefit cirrhotics with refractory ascites?

Hyponatremia is a frequent complication of advanced cirrhosis with ascites associated with increased morbidity and mortality. It is caused by an impairment in the renal capacity to eliminate solute-free water and is considered to be related to persistent secretion of vasopressin despite low serum osmolality. This nonosmotic release of vasopressin is mediated by the autonomic nervous system, which senses the underfilling of arterial vascular component. This reduction of effective arterial blood volume is closely related to the development of ascites. Although the short-time effects of vasopressin V2 receptor antagonists (vaptans) on hyponatremia and ascites have been repeatedly reported, their effects on the long-term management of cirrhotic ascites have not been established yet. Considering that their effects on water diuresis and their safety are limited by severe underfilling state of patients, cautious approaches with adequate monitoring are needed to advanced cirrhosis. Proper indication, adequate doses and new possibility of combination therapy should be explored in the future controlled study. As hyponatremia is frequent obstacle to ascites management, judicious combination with low-dose diuretics may decrease the incidence of refractory ascites. Although vaptans show much promise in the treatment of advanced cirrhosis, the problem of high cost should be solved for the future.

Hyponatremia in Cirrhosis--Pathogenesis, Treatment, and Prognostic Significance

Cirrhosis is characterized by systemic and splanchnic vasodilation that leads to excessive nonosmotic secretion of vasopressin (antidiuretic hormone). Hyponatremia is a common electrolyte abnormality in advanced liver disease that results from the impaired ability of the kidney to excrete solute-free water that leads to "dilutional" hyponatremia-water retention disproportionate to the retention of sodium. Hyponatremia in liver diseases carries the prognostic burden, correlates with the severity of cirrhosis, and, in recent studies, has also been implicated in the pathogenesis of hepatic encephalopathy. The current treatment options are limited to conventional therapies like fluid restriction, and the outcomes are unsatisfactory. Although currently available vasopressin (V2 receptors) antagonists have been shown to increase serum sodium concentrations and improve ascites control, their role in the treatment of hyponatremia in liver disease patients remains questionable because of adverse effect profiles, high cost, and poor data on long-term mortality benefits. More information is needed to argue the benefits vs risks of short-term use of vaptans for correction of hyponatremia especially just hours-to-days before liver transplant.

[Hyponatremias: From pathophysiology to treatments. Review for clinicians]

Hyponatremia could be defined as a public health topic: too many patients are concerned in both hospitalized and general populations; hyponatremia induces lots of clinical outcomes and a great economic burden. Its pathophysiology involves thirst regulation (hypotonic water intakes) and losses regulation (through the kidney under vasopressin control). Diagnostic approach should insure that hyponatremia reflects hypo-osmolality and hypotonicity: first, a false hyponatremia should be ruled out, then a non-hypotonic one. Next step is clinic: extracellular status should be evaluated. When increased, any edematous status should be evoked: heart failure, liver cirrhosis or nephrotic syndrome. When decreased, any cause of extracellular dehydration should be evoked: natriuresis could help distinguishing between renal (adrenal insufficiency, diuretics use or salt-losing nephropathy) or extrarenal (digestive mostly) etiologies. When clinically normal, a secretion of inappropriate antidiuretic hormone (SIADH) should be evoked, once hypothyroidism or hypoadrenocorticism have been ruled out. Therapy depends on the severity of the clinical impact. From extracellular rehydration, through fluid restriction, the paraneoplastic and heart failure-induced SIADH benefit from a new class of drug, available among the therapeutic strategies: aquaretics act through antidiuretic hormone receptor antagonism (vaptans). Their long-term benefits still have to be proven but it is a significant step forward in the treatment of hyponatremias.

The treatment of vasopressin V2-receptor antagonists in cirrhosis patients with ascites: a meta-analysis of randomized controlled trials

Background

Ascites is the most common complication of cirrhosis. It may lead to the consequence of poor prognosis and the deterioration of quality of life. Asopressin V2 receptor antagonists is a kind of vaptans, and it has been proved to be effective in hyponatremia patients. We conducted a meta-analysis about treatment of vaptans in cirrhosis patients with ascites.

Methods

Following our selection criteria, we collected a total of 14 studies containing 16 randomized controlled trials (2620 patients) from a series of database about the treatment with vaptans for cirrhosis with ascites patients. The included studies compared the treatment effect of lixivaptan (VPA 985), or RMJ-351647, or satavaptan, or tolvaptan with placebo.

Results

The included vaptans (asopressin V2 receptor antagonists) showed significant effect of increasing the serum sodium concentration for cirrhosis patients (WMD = 2.11 mmol/L, p < 0.00001). Patients also could acquire significant improvement of ascites, as this kind of aquaretics can significantly reduce ascites patients’ weight (WMD = −1.53, p < 0.00001), abdominal girth (WMD = −2.04, p < 0.00001), and the ratio of worsening ascites (RR = 0.51, p = 0.001). Though the drug did not produce more total adverse events (RR = 1.04, p = 0.09) and the total serious events (RR = 1.04, p = 0.42), the emergence of excessive correction of serum sodium concentrations (>145 mmol/L) was more frequently noted in patients under the employment of vaptans (RR = 2.14, 95 % CI [1.45, 3.16], p = 0.0001). Whether with the administration of vaptans for short-term or long-term, no survival benefit was detected from the selected studies.

Conclusions

Asopressin V2 receptor antagonists could play an effective and safe role in symptomatic treatment for cirrhosis patients with ascites, especially for refractory ascites patients who presented insufficient response to conventional diuretics.

Hyponatremia in cirrhosis: Pathophysiology and management

Hyponatremia is frequently seen in patients with ascites secondary to advanced cirrhosis and portal hypertension. The development of ascites in patients with cirrhosis is multi-factorial. Portal hypertension and the associated systemic vasodilation lead to activation of the sodium-retaining neurohumoral mechanisms which include the renin-angiotensin-aldosterone system, sympathetic nervous system and antidiuretic hormone (ADH). The net effect is the avid retention of sodium and water to compensate for the low effective circulatory volume resulting in the development of ascites. Although not apparent in the early stages of cirrhosis, the progression of cirrhosis and ascites leads to impairment of the kidneys to eliminate solute- free water. This leads to additional compensatory mechanisms including non-osmotic secretion of ADH, also known as arginine vasopressin, further worsening excess water retention and thereby hyponatremia. Hyponatremia is associated with increased morbidity and mortality in patients with cirrhosis, and is an important prognostic marker both before and after liver transplant. The management of hyponatremia in this setting is a challenge as conventional therapy for hyponatremia including fluid restriction and loop diuretics are frequently inefficacious. In this review, we discuss the pathophysiology and various treatment modalities, including selective vasopressin receptor antagonists, for the management of hyponatremia in patients with cirrhosis.

Management of hyponatraemia in older people: old threats and new opportunities

Hyponatraemia is the commonest electrolyte abnormality seen in clinical practice, and is especially prevalent in frail, older people. However, the serious implications of hyponatraemia in this age group are seldom recognized by clinicians. Hyponatraemia is associated with osteoporosis, impaired balance, falls, hip fractures and cognitive dysfunction. Even mild, apparently asymptomatic hyponatraemia is associated with prolonged stays in hospital, institutionalization and increased risk of death. Emerging evidence of the potential benefits of improved treatment of hyponatraemia is slowly generating renewed clinical interest in this area. The development of specific vasopressin-2 receptor antagonists (vaptans) has the potential to revolutionize the management of hyponatraemia, in particular for the syndrome of inappropriate antidiuretic hormone. However, challenges remain for the attending physician. Diagnosing the cause or causes of hyponatraemia in older people is difficult, and incorrect diagnosis can lead to treatment that worsens the electrolyte imbalance. Established treatments are often poorly tolerated and patient outcomes remain poor, and the role of vaptans in the treatment of older people is unclear. This review summarizes the existing evidence base and highlights areas of controversy. It includes practical guidance for overcoming some common pitfalls in the management of the elderly patient with hyponatraemia.

Defining the role of albumin infusion in cirrhosis-associated hyponatremia

The presence of negatively charged, impermeant proteins in the plasma space alters the distribution of diffusible ions in the plasma and interstitial fluid (ISF) compartments to preserve electroneutrality and is known as Gibbs-Donnan equilibrium. In patients with hypoalbuminemia due to underlying cirrhosis, the decrease in the plasma water albumin concentration ([Alb-]pw) would be expected to result in a decrease in the plasma water sodium concentration ([Na+]pw) due to an alteration in the distribution of Na+ between the plasma and ISF. In addition, cirrhosis-associated hyponatremia may be due to the renal diluting defect resulting from the intravascular volume depletion due to gastrointestinal losses and overdiuresis and/or decreased effective circulatory volume secondary to splanchnic vasodilatation. Therefore, albumin infusion may result in correction of the hyponatremia in cirrhotic patients either by modulating the Gibbs-Donnan effect due to hypoalbuminemia or by restoring intravascular volume in patients with intravascular volume depletion due to gastrointestinal losses and overdiuresis. However, the differential role of albumin infusion in modulating the [Na+]pw in these patients has not previously been analyzed quantitatively. In the present study, we developed an in vitro assay system to examine for the first time the quantitative effect of changes in albumin concentration on the distribution of Na+ between two compartments separated by a membrane that allows the free diffusion of Na+. Our findings demonstrated that changes in [Alb-]pw are linearly related to changes in [Na+]pw as predicted by Gibbs-Donnan equilibrium. However, based on our findings, we predict that the improvement in cirrhosis-associated hyponatremia due to intravascular volume depletion results predominantly from the restoration of intravascular volume rather than alterations in Gibbs-Donnan equilibrium.

Cirrhosis and its complications: Evidence based treatment

Cirrhosis results from progressive fibrosis and is the final outcome of all chronic liver disease. It is among the ten leading causes of death in United States. Cirrhosis can result in portal hypertension and/or hepatic dysfunction. Both of these either alone or in combination can lead to many complications, including ascites, varices, hepatic encephalopathy, hepatocellular carcinoma, hepatopulmonary syndrome, and coagulation disorders. Cirrhosis and its complications not only impair quality of life but also decrease survival. Managing patients with cirrhosis can be a challenge and requires an organized and systematic approach. Increasing physicians’ knowledge about prevention and treatment of these potential complications is important to improve patient outcomes. A literature search of the published data was performed to provide a comprehensive review regarding the management of cirrhosis and its complications.

Review article: advances in the management of patients with cirrhosis and portal hypertension-related renal dysfunction

BACKGROUND

In cirrhosis, portal hypertension is associated with a spectrum of renal dysfunction that has significant implications for morbidity and mortality.

AIM

To discuss recent progress in the patho-physiological mechanisms and therapeutic options for portal hypertension-related renal dysfunction.

METHODS

A literature search using Pubmed was performed.

RESULTS

Portal hypertension-related renal dysfunction occurs in the setting of marked neuro-humoral and circulatory derangement. A systemic inflammatory response is a pathogenetic factor in advanced disease. Such physiological changes render the individual vulnerable to further deterioration of renal function. Patients are primed to develop acute kidney injury when exposed to additional 'hits', such as sepsis. Recent progress has been made regarding our understanding of the aetiopathogenesis. However, treatment options once hepatorenal syndrome develops are limited, and prognosis remains poor. Various strategies to prevent acute kidney injury are suggested.

CONCLUSION

Prevention of acute kidney injury in high risk patients with cirrhosis and portal hypertension-related renal dysfunction should be a clinical priority.

Clinical practice guideline on diagnosis and treatment of hyponatraemia

Hyponatraemia, defined as a serum sodium concentration <135 mmol/l, is the most common disorder of body fluid and electrolyte balance encountered in clinical practice. It can lead to a wide spectrum of clinical symptoms, from subtle to severe or even life threatening, and is associated with increased mortality, morbidity and length of hospital stay in patients presenting with a range of conditions. Despite this, the management of patients remains problematic. The prevalence of hyponatraemia in widely different conditions and the fact that hyponatraemia is managed by clinicians with a broad variety of backgrounds have fostered diverse institution- and speciality-based approaches to diagnosis and treatment. To obtain a common and holistic view, the European Society of Intensive Care Medicine (ESICM), the European Society of Endocrinology (ESE) and the European Renal Association - European Dialysis and Transplant Association (ERA-EDTA), represented by European Renal Best Practice (ERBP), have developed the Clinical Practice Guideline on the diagnostic approach and treatment of hyponatraemia as a joint venture of three societies representing specialists with a natural interest in hyponatraemia. In addition to a rigorous approach to methodology and evaluation, we were keen to ensure that the document focused on patient-important outcomes and included utility for clinicians involved in everyday practice.

Clinical practice guideline on diagnosis and treatment of hyponatraemia

Hyponatraemia, defined as a serum sodium concentration <135 mmol/l, is the most common disorder of body fluid and electrolyte balance encountered in clinical practice. It can lead to a wide spectrum of clinical symptoms, from subtle to severe or even life threatening, and is associated with increased mortality, morbidity and length of hospital stay in patients presenting with a range of conditions. Despite this, the management of patients remains problematic. The prevalence of hyponatraemia in widely different conditions and the fact that hyponatraemia is managed by clinicians with a broad variety of backgrounds have fostered diverse institution- and speciality-based approaches to diagnosis and treatment. To obtain a common and holistic view, the European Society of Intensive Care Medicine (ESICM), the European Society of Endocrinology (ESE) and the European Renal Association - European Dialysis and Transplant Association (ERA-EDTA), represented by European Renal Best Practice (ERBP), have developed the Clinical Practice Guideline on the diagnostic approach and treatment of hyponatraemia as a joint venture of three societies representing specialists with a natural interest in hyponatraemia. In addition to a rigorous approach to methodology and evaluation, we were keen to ensure that the document focused on patient-important outcomes and included utility for clinicians involved in everyday practice.

Hyponatraemia and cirrhosis

Hyponatraemia is a common complication of advanced cirrhosis related to an impairment in the renal capacity for eliminating solute-free water, causing a retention of water that is disproportionate to the retention of sodium, thus leading to a reduction in serum sodium concentration and hypo-osmolality. The main pathogenic factor responsible for hyponatraemia is a non-osmotic hypersecretion of arginine vasopressin (AVP) or antidiuretic hormone from the neurohypophysis, related to circulatory dysfunction. Hyponatraemia in cirrhosis is associated with increased morbidity and mortality. Hyponatraemia is also associated with increased morbidity and impaired short-term survival after transplantation. The current standard of care based on restricting fluids to 1-1.5 L/day is rarely effective. Other approaches, such as albumin infusion and the use of vaptans-which act by specifically antagonizing the effects of AVP on the V2 receptors located in the kidney tubules-have been evaluated for their role in the management of hyponatraemia. The short-term treatment with vaptans is associated with a marked increase in renal solute-free water excretion and improvement of hyponatraemia; however their use in patients with end-stage liver disease is limited by hepatotoxic effects of some of these drugs. Long-term administration of vaptans seems to be effective in maintaining the improvement of serum sodium concentration, but the available information is still limited.

Vasopressin antagonists in the management of heart failure

Vasopressin antagonists have been studied in a variety of clinical settings, including patients with acute and chronic heart failure. The clinical trials published to date have sought to describe the clinical and physiologic effects of these agents in an effort to prove clinical efficacy and safety. A variety of agents with varying effects on V2 and V1a vasopressin receptor subtype have been studied. They have been shown to reduce bodyweight and improve serum sodium without worsening renal function. They may also decrease the need for loop diuretic use and may be particularly useful in patients with hyponatremia in the setting of volume overload. Further studies are underway that are powered to assess for morbidity and mortality benefits. The beneficial effects have been well documented but, until outcomes are understood more fully, the use of these agents should be limited to currently approved indications. In the USA, this includes only the treatment of euvolemic hyponatremia.

Renal aquaporins and water balance disorders

BACKGROUND

Aquaporins (AQPs) are a family of proteins that can act as water channels. Regulation of AQPs is critical to osmoregulation and the maintenance of body water homeostasis. Eight AQPs are expressed in the kidney of which five have been shown to play a role in body water balance; AQP1, AQP2, AQP3, AQP4 and AQP7. AQP2 in particular is regulated by vasopressin.

SCOPE OF REVIEW

This review summarizes our current knowledge of the underlying mechanisms of various water balance disorders and their treatment strategies.

MAJOR CONCLUSIONS

Dysfunctions of AQPs are involved in disorders associated with disturbed water homeostasis. Hyponatremia with increased AQP levels can be caused by diseases with low effective circulating blood volume, such as congestive heart failure, or osmoregulation disorders such as the syndrome of inappropriate secretion of antidiuretic hormone. Treatment consists of fluid restriction, demeclocycline and vasopressin type-2 receptor antagonists. Decreased AQP levels can lead to diabetes insipidus (DI), characterized by polyuria and polydipsia. In central DI, vasopressin production is impaired, while in gestational DI, levels of the vasopressin-degrading enzyme vasopressinase are abnormally increased. Treatment consists of the vasopressin analogue dDAVP. Nephrogenic DI is caused by the inability of the kidney to respond to vasopressin and can be congenital, but is most commonly acquired, usually due to lithium therapy. Treatment consists of sufficient fluid supply, low-solute diet and diuretics.

GENERAL SIGNIFICANCE

In recent years, our understanding of the underlying mechanisms of water balance disorders has increased enormously, which has opened up several possible new treatment strategies. This article is part of a Special Issue entitled Aquaporins.

Role of vaptans in the management of hyponatremia

Hyponatremia, the most commonly encountered electrolyte abnormality, affects as many as 30% of hospitalized patients. It is a powerful predictor of poor outcomes, especially in patients with congestive heart failure or cirrhosis. The failure to excrete electrolyte-free water that results from persistent secretion of antidiuretic hormone despite low serum osmolality usually underlies the development of hyponatremia. Treatment depends on several factors, including the cause, overall volume status of the patient, severity of hyponatremic symptoms, and duration of hyponatremia at presentation. This review focuses on the role of the vasopressin receptor antagonists, or vaptans, in the treatment of hyponatremia. These recently introduced agents have the unique ability to induce an aquaresis, the excretion of electrolyte-free water without accompanying solutes. After a brief historical perspective and discussion of pharmacologic characteristics of vaptans, we review the accumulated experience with vaptans for the treatment of hyponatremia. Vaptans have been shown to increase serum sodium concentrations in patients with euvolemic or hypervolemic hyponatremia in a reproducible manner, but their safe use requires full understanding of their indications and contraindications.

Evaluation of lixivaptan in euvolemic and hypervolemic hyponatremia and heart failure treatment

INTRODUCTION

Lixivaptan is a selective vasopressin type 2 (V2) receptor antagonist that induces aquaresis, the electrolytes sparing excretion of water. Its ability to correct hyponatremia has been demonstrated in experimental animal studies as well as in clinical trials in humans. Recently, three Phase III, double-blind, randomized, placebo-controlled studies have been completed. In two studies, patients with euvolemic hyponatremia were enrolled, one in the inpatient and the other in the outpatient setting and the third study involved patients with hypervolemic hyponatremia hospitalized for decompensated heart failure (HF). The trials confirmed the efficacy of lixivaptan in raising serum sodium but raised concern about its safety in patients hospitalized with decompensated HF.

AREAS COVERED

The authors review original publications on lixivaptan and summarize their findings. Specifically, the authors present information regarding its structure, pharmacodynamics and kinetics, metabolism as well as its efficacy and safety in laboratory animals and human studies. Furthermore, the FDA website was accessed to obtain information presented at the September 13, 2012 meeting of the Cardiovascular and Renal Drugs Advisory Committee.

EXPERT OPINION

The published data indicate that lixivaptan raises sodium levels in hyponatremic patients and supports its use in patients with euvolemic hyponatremia. However, the authors note that more safety data are still needed specifically in patients with decompensated HF.

Clinical review: the use of vaptans in clinical endocrinology

CONTEXT

Hyponatremia is the most common electrolyte disorder encountered in clinical practice and represents a clinical, social, and economic burden. Conventional treatments of hyponatremia present some pitfalls, such as suboptimal efficacy, risk of overly rapid correction, and adverse effects. Vasopressin receptor antagonists, known as vaptans, represent a new and interesting class of drugs for the treatment of the euvolemic and hypervolemic forms of hyponatremia.

EVIDENCE ACQUISITION

This review is based on a PubMed search with the following terms: "vaptans," "vasopressin receptor antagonists," "tolvaptan," "conivaptan," "vasopressin receptor antagonists and SIADH," "vasopressin receptor antagonists and congestive heart failure," "vasopressin receptor antagonists and cirrhosis," and "vasopressin receptor antagonists and polycystic kidney disease."

EVIDENCE SYNTHESIS

Overall, the studies reported in this review indicate that vaptans effectively correct hyponatremia in euvolemic and hypervolemic patients. In the latter group, vaptans generally had favorable effects on fluid balance also. To date two vaptans, ie, conivaptan and tolvaptan, have been marketed in the United States for the treatment of euvolemic and hypervolemic hyponatremia, whereas tolvaptan has been marketed in Europe with the limitation of euvolemic hyponatremia. Although these drugs have a good safety profile, caution should be used, and treatment should be initiated in a hospital setting in order to closely monitor patients and avoid overly rapid correction or overcorrection.

CONCLUSIONS

Vaptans can be considered a new effective tool for the treatment of euvolemic and hypervolemic hyponatremia. Nevertheless, more comparative research of vaptans vs other therapies on clinical grounds is needed to more accurately assess the value of these drugs in the treatment of hyponatremia.

Child-Na score: a predictive model for survival in cirrhotic patients with symptomatic portal hypertension treated with TIPS

BACKGROUND AND AIM

Several models have been developed to predict survival in patients with cirrhosis undergoing TIPS; however, few of these models have gained widespread acceptance, especially in the era of covered stents. The aim of this study was to establish an evidence-based model for predicting survival after TIPS procedures.

METHODS

A total of 210 patients with cirrhosis treated with TIPS were considered in the study. We comprehensively investigated factors associated with one-year survival and developed a new predictive model using the Cox regression model.

RESULTS

In the multivariate analysis, the Child-Pugh score and serum sodium levels were independent predictors of one-year survival. A new score incorporating serum sodium into the Child-Pugh score was developed: Child-Na score. We compared the predictive accuracy of Child-Na score with that of other scores; only the Child-Na and MELD-Na scores had adequate predictive ability in patients with serum Na levels <138 mmol/L. The best Child-Na cut-off score (15.5) differentiated two groups of patients with distinct prognoses (one-year cumulative survival rates of 80.6% and 45.5%); this finding was confirmed in a validation cohort (n = 86). In a subgroup analysis stratifying patients by indication for TIPS, the Child-Na score distinguished patients with different prognoses.

CONCLUSIONS

Patients with variceal bleeding and a Child-Na score ≤15 had a better prognosis than patients with a score ≥16. Patients with refractory ascites and a Child-Na score ≥16 had a high risk of death after the TIPS procedures; caution should be used when treating these patients with TIPS.

Meta-analysis: the safety and efficacy of vaptans (tolvaptan, satavaptan and lixivaptan) in cirrhosis with ascites or hyponatraemia

BACKGROUND

Vaptans may correct hyponatraemia and mobilise ascites through an increased excretion of water. The effect on clinical outcomes is debated.

AIM

To determine the effects of vaptans (tolvaptan, satavaptan and lixivaptan) on patients with cirrhosis and hyponatraemia or ascites.

METHODS

Systematic review of randomised controlled trials. The primary outcome measure was mortality. Electronic and manual searches were combined (April 2012). Data were extracted from published reports, online information from the Food and Drug Administration website or obtained through correspondence with authors and pharmaceutical companies. The primary meta-analyses were performed using random effects models due to an expected clinical diversity.

RESULTS

Twelve trials with a total of 2266 patients were included. Randomisation was adequate in all trials. Eight trials were double-blind. Random effects meta-analyses found no clear differences between vaptans and control groups regarding mortality (RR = 1.06, 95% CI = 0.90-1.26, I(2) = 0%), variceal bleeding, hepatic encephalopathy, spontaneous bacterial peritonitis, hepatorenal syndrome, or renal failure. Vaptans increased serum sodium levels (WMD = 1.8 mmol/L, 95% CI = 0.79-2.96) and lead to reductions in weight and the time to the first paracentesis. Vaptans increased the risk of adverse events (RR = 3.97, 95% CI = 1.78-8.83), including an excessive urine volume (RR = 9.96, 95% CI = 1.38-71.68).

CONCLUSIONS

Vaptans have a small beneficial effect on hyponatraemia and ascites, but do not affect mortality, complications to cirrhosis or renal failure. The data do not support the routine use of vaptans in cirrhosis.

Oral lixivaptan effectively increases serum sodium concentrations in outpatients with euvolemic hyponatremia

Hyponatremia is the most common electrolyte disorder in clinical practice. Its incidence increases with age and it is associated with increased morbidity and mortality. Recently, the vaptans, antagonists of the arginine vasopressin pathway, have shown promise for safe treatment of hyponatremia. Here we evaluated the efficacy, safety, and tolerability of oral lixivaptan, a selective vasopressin V2-receptor antagonist, for treatment of nonhospitalized individuals with euvolemic hyponatremia (sodium less than 135 mmol/l) in a multicenter, randomized, double-blind, placebo-controlled, phase III study. About half of the 206 patients were elderly in a chronic care setting. Of these patients, 52 were given a placebo and 154 were given 25-100 mg per day lixivaptan, titrated based on the daily serum sodium measurements. Compared with placebo (0.8 mmol/l), the serum sodium concentration significantly increased by 3.2 mmol/l from baseline to day 7 (primary efficacy endpoint) with lixivaptan treatment. A significantly greater proportion of patients that received lixivaptan achieved normal serum sodium (39.4%) by day 7 relative to placebo (12.2%). Overall, lixivaptan was considered safe and well-tolerated. Thus, oral lixivaptan can be safely initiated in the outpatient setting and effectively increases serum sodium concentrations in outpatients with euvolemic hyponatremia.

Vasopressin V2-receptor antagonists in patients with cirrhosis, ascites and hyponatremia

Hyponatremia is a common problem in patients with advanced cirrhosis. It develops slowly (paralleling the rate of progression of the liver disease) and usually produces no neurological symptoms, although it may exacerbate hepatic encephalopathy. For patients awaiting liver transplantation a low serum sodium level is a strong predictor of pretransplant mortality, independent of the Model for End-stage Liver Disease score (MELD). The pathogenesis of hyponatremia is related to the hemodynamic changes and secondary neurohormonal adaptations that occur in patients with cirrhosis and ascites. The nonosmotic release of arginine vasopressin is the principle cause of the hyponatremia and vasopressin-receptor antagonists are a new class of drugs recently approved for treatment of cirrhotic hyponatremia. In this article we review the safety and efficacy of V2-receptor antagonists in patients with cirrhosis, ascites and hyponatremia.

Tolvaptan, an oral vasopressin antagonist, in the treatment of hyponatremia in cirrhosis

BACKGROUND & AIMS

Tolvaptan is a vasopressin V2-receptor antagonist that improves serum sodium concentration by increasing renal solute-free water excretion. Specific data on the safety and efficacy of tolvaptan in patients with cirrhosis and hyponatremia has not been exclusively evaluated.

METHODS

This sub-analysis of the Study of Ascending Levels of Tolvaptan trials examined cirrhotic patients with hyponatremia who received 15 mg oral tolvaptan (n=63; increased to 30 or 60 mg if needed) or placebo (n=57) once-daily for 30 days. At baseline, 44% had mild hyponatremia (serum sodium 130-134 mmol/L), 56% had marked hyponatremia (serum sodium <130 mmol/L), 85% had cirrhosis due to alcohol and/or hepatitis B/C, and 80% were Child-Pugh class B/C.

RESULTS

Tolvaptan was effective in raising serum sodium. Average daily area under the curve for serum sodium was significantly greater in the tolvaptan group from baseline to day 4 (p<0.0001) and day 30 (p<0.0001). This superiority was maintained after stratification by baseline hyponatremia (mild and marked), estimated glomerular filtration rate (≤ 60 ml/min and >60 ml/min), or serum creatinine levels (<1.5mg/dl and ≥ 1.5mg/dl). Hyponatremia recurred 7 days after discontinuation of tolvaptan. Mean mental component summary scores of the SF-12 health survey improved from baseline to day 30 in the tolvaptan group but not the placebo group (4.68 vs. 0.08, p=0.02). Major side effects due to tolvaptan were dry mouth and thirst. Gastrointestinal bleeding occurred in 10% and 2% of patients in the tolvaptan and placebo group, respectively (p=0.11). Adverse event rates, withdrawals, and deaths were similar in both groups.

CONCLUSIONS

One month of tolvaptan therapy improved serum sodium levels and patient-reported health status in cirrhotic patients with hyponatremia. Hyponatremia recurred in tolvaptan-treated patients after discontinuation.