Oral V2 receptor antagonist (RWJ-351647) in patients with cirrhosis and ascites: a randomized, double-blind, placebo-controlled, single ascending dose study

Efficacy and safety of tolvaptan in cirrhotic patients: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND AIMS

Tolvaptan has been approved for the management of cirrhosis-related complications according to the Japanese and Chinese practice guidelines, but not the European or American practice guidelines in view of FDA warning about its hepatotoxicity. This study aimed to systematically evaluate its efficacy and safety in cirrhosis.

METHODS

The PubMed, EMBASE, and Cochrane library databases were searched to identify randomized controlled trials (RCTs) evaluating the efficacy and/or safety of tolvaptan in cirrhosis. Risk ratios (RRs) and weight mean differences (WMDs) were calculated. The incidence of common adverse events (AEs) was pooled.

RESULTS

Eight RCTs were included. Tolvaptan was significantly associated with higher rates of improvement of ascites (RR = 1.49, P < 0.001) and hyponatremia (RR = 1.80, P = 0.005) and incidence of any AEs (RR = 1.18, P = 0.003), but not serious AEs (RR = 0.86, P = 0.410). Tolvaptan was significantly associated with reductions in body weight (WMD = -1.30 kg, P < 0.001) and abdominal circumference (WMD = -1.71 cm, P < 0.001), and increases in daily urine volume (WMD = 1299.84 mL, P < 0.001) and serum sodium concentration (WMD = 2.57 mmol/L, P < 0.001). The pooled incidences of dry mouth, thirst, constipation, and pollakiuria were 16%, 24%, 6%, and 17%, respectively.

CONCLUSION

Short-term use of tolvaptan may be considered in cirrhotic patients with ascites who have inadequate response to conventional diuretics and those with hyponatremia.

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.

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.

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.

Red blood cell sodium transport in patients with cirrhosis

Patients with advanced cirrhosis have abnormal sodium homoeostasis. The study was undertaken to quantify the sodium transport across the plasma membrane of red blood cells (RBC) in patients with cirrhosis. RBC efflux and influx of sodium were studied in vitro with tracer (22) Na(+) according to linear kinetics in 24 patients with cirrhosis and 14 healthy controls. The sodium efflux was modified by ouabain (O), furosemide (F) and a combination of O and F (O + F). RBC sodium was significantly decreased (4·6 versus control 6·3 mmol l(-1) , P<0·001) and directly related to serum sodium (r = 0·57, P<0·05). The RBC fractional sodium efflux was higher in patients with cirrhosis (+46%, P<0·01) compared to controls. Inhibition in both high (145 mmol l(-1) )- and low (120 mmol l(-1) )-sodium buffers showed that the F-insensitive sodium efflux was twice as high in cirrhosis as in controls (P = 0·03-0·007), especially the O-sensitive, F-insensitive efflux was increased (+ 225%, P = 0·01-0·006). Fractional F-sensitive transport was normal in cirrhosis. RBC sodium influx was largely normal in cirrhosis. In conclusion, RBC sodium content is reduced in patients with cirrhosis with a direct relation to serum sodium. Increased RBC sodium efflux is especially related to ouabain-sensitive, furosemide-insensitive transport and thus most likely due to upregulated activity of the sodium-potassium pump. The study gives no evidence to an altered intracellular/extracellular sodium ratio or to a reduced fractional furosemide-sensitive sodium transport in cirrhosis.

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.

Re-response to tolvaptan after furosemide dose reduction in a patient with refractory ascites

Tolvaptan is a new drug used for treating ascites induced by liver cirrhosis, and it is covered by health insurance in Japan. In the present report, we describe the case of a 74-year-old man with type C liver cirrhosis and refractory ascites. He was receiving furosemide and spironolactone daily, but still required repeat puncture for ascites removal. Administration of tolvaptan (3.75 mg/day) was started in addition to his existing medications, and was subsequently increased to 7.5 mg/day. However, after 2 months, the ascites again exacerbated. Nevertheless, after we discontinued the administration of furosemide, the tolvaptan became effective. This may be because furosemide administration decreases urine osmolality, resulting in a non-response to tolvaptan.

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.

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.

Hyponatremia in cirrhosis and vaptans

Hyponatremia is a common problem in patients with advanced cirrhosis. Hyponatremia in cirrhosis includes two distinct types: hypovolemic hyponatremia, and hypervolemic or dilutional hyponatremia. The former is characterized by low blood sodium, low blood volume, dehydration and prerenal renal dysfunction, not accompanied by edema and ascites, while the latter is characterized by insufficient circulatory volume and dilutional hyponatremia, accompanied by edema and ascites. Hyponatremia is closely related to various complications of cirrhosis and to early mortality after liver transplantation. Vaptans, a class of selective non-peptide arginine vasopressin (AVP) receptor antagonists, act by antagonizing specifically the effects of AVP V₂ receptor located in the renal collecting tubules to inhibit water reabsorption without affecting electrolytes excretion. Vaptans has been evaluated by several clinical trials for their role in the management of hyponatremia. The short-term treatment with vaptans is associated with a marked increase in renal solute-free water excretion and improvement of hyponatremia with no apparent adverse reactions. The discovery of vaptans is considered a new milestone in the management of hyponatremia in cirrhosis.

Conivaptan increases serum sodium in hyponatremic patients with end-stage liver disease

Hyponatremia is associated with increased mortality in patients with end-stage liver disease and a greater risk of perioperative mortality with liver transplantation. We performed a retrospective review of our experience with conivaptan as a means of acutely increasing serum sodium in end-stage liver disease patients. The primary group consisted of 15 patients with end-stage liver disease who remained hyponatremic despite discontinuation of diuretics and a 1-L fluid restriction. Twenty milligrams of conivaptan was intravenously administered over 30 minutes, and this was followed by an infusion of 20 mg over 24 hours for 1 to 4 days. A second group of 9 hyponatremic end-stage liver disease patients was treated with 1-L fluid restriction and conivaptan while remaining on diuretics. In the group without diuretics, the mean serum sodium was 124 mmol/L 1 day before and on the day of conivaptan initiation, but the serum sodium rose to a mean of 127.7 mmol/L by day 1 and further increased to 128.6 mmol/L by the second day of the infusion. Despite the continuation of diuretics, the second group of 9 patients also had an increase in serum sodium from the day of conivaptan initiation (125.7 mmol/L) to 2 days after the treatment (130.6 mmol/L). Eleven patients underwent successful liver transplantation, 2 remained on the list for transplantation, and 11 were not candidates for transplantation and either died (7) or were discharged home and lost to follow-up (4). In conclusion, a short course of conivaptan increases serum sodium in patients with end-stage liver disease and may reduce the risk of proceeding to liver transplantation. Further study in a prospective clinical trial is needed to confirm safety and efficacy.

Effect of hyponatraemia on outcomes following orthotopic liver transplantation

BACKGROUND

Hyponatraemia increases risk of adverse outcomes following orthotopic liver transplantation (OLT), but it is unclear whether improvement of pretransplant hyponatraemia ameliorates post-transplant complications.

AIMS

To assess impact of pretransplant hyponatraemia on post-transplant outcomes.

METHODS

We performed a retrospective analysis of 213 patients with cirrhosis who underwent liver transplantation. Patients with serum sodium <or=130 mEq/L immediately before transplantation ('hyponatraemia at OLT'; n=34) were compared with those who had experienced hyponatraemia but subsequently improved to a serum sodium >130 mEq/L at transplantation ('resolved hyponatraemia'; n=56) and to those without history of hyponatraemia before transplantation ('never hyponatraemic'; n=123). Primary endpoint was survival at 180 days post-OLT. Secondary outcomes included time until discharge alive, complications during hospitalization, length of time ventilated and length of post-transplant intensive care unit stay.

RESULTS

There was no survival difference at 180 days post-OLT between groups. After transplantation, patients with either hyponatraemia at OLT or resolved hyponatraemia had longer time until discharge alive and had higher rates of delirium, acute renal failure, acute cellular rejection and infection than those who were never hyponatraemic. As compared with patients with hyponatraemia at OLT, those with resolved hyponatraemia were more likely to be discharged alive within 3 weeks, but other outcomes, including survival, did not differ significantly.

CONCLUSIONS

We conclude that hyponatraemia at any time before liver transplantation is associated with adverse post-transplant outcome, even when hyponatraemia has resolved.

Altered central TRPV4 expression and lipid raft association related to inappropriate vasopressin secretion in cirrhotic rats

Inappropriate vasopressin (AVP) release causes dilutional hyponatremia in many pathophysiological states such as cirrhosis. The central molecular mechanisms that mediate inappropriate AVP release are unknown. We tested the hypothesis that changes in the expression or trafficking of TRPV4 in the central nervous system may contribute to inappropriate AVP release in the bile duct ligation (BDL) model of cirrhosis in the rat. Four weeks after surgery, BDL rats demonstrated significantly increased plasma vasopressin and plasma renin activity (PRA), hypervolemia, and decreased plasma osmolality. These effects were blocked by providing BDL rats with 2% saline to drink for 15 days. TRPV4 protein expression was significantly increased in brain punches from BDL rats containing the supraoptic nucleus (SON) of the hypothalamus (100% +/- 11 to 157% +/- 4.8), and this effect was blocked in BDL rats given saline. Immunohistochemistry demonstrated a significant increase in TRPV4-positive cells and the percentage of AVP neurons that also were TRPV4-positive in the SON of BDL rats. In the hypothalamus of BDL rats, TRPV4 lipid raft association increased compared with sham (from 100% +/- 2.1 to 326.1% +/- 16). This effect was significantly attenuated in BDL rats given 2% saline to drink (174% +/- 11). In the brain stem, TRPV4 lipid raft association was reduced by BDL and inversely related to plasma AVP and PRA. We speculate that changes in TRPV4 expression and compartmentalization within lipid rafts could contribute to a feed-forward mechanism related to AVP release in cirrhosis.

Liver-kidney pathophysiological interrelationships in liver diseases

On the basis of several clinical and experimental researches, it is possible today to deepen the different mechanisms regarding kidney and liver relationships. However, the most studied field remains the renal function during liver disease. These alterations can be divided into: 1. Renal functional impairment is mainly considered due to hemodynamic derangement with a progressive decrease in peripheral vascular resistance (PVR) and an increase in cardiac output and rate, characteristic of hyperdynamic circulation, and outer cortex renal ischemia. Two principal forms of RFI characterize the hepatorenal syndrome (HRS) while in the first stage is based on the simple decrease in renal clearances with avid sodium retention. 2. Metabolic renal damage is principally due to abnormal serum levels of bile acids, bilirubin and perhaps toxic hepatic molecules which induce tubular dysfunction leading to RTA, of which type I, in the incomplete form, is the most common, varying between 30% and 50% of cases. It is mainly studied during cholestatic disease. 3. Organic renal impairment is principally based on immunological response to viral antigens and abnormal hepatic products which lead to the presence of immunocomplexes and cryoglobulins on the blood which tend to be deposited in the subendothelial and subepithelial glomerular areas, inducing complement activation, mesangial cell proliferation and monocyte-macrophage cell infiltration.

Pharmacology of vasopressin antagonists

Congestive heart failure (CHF) is characterized by fluid and water retention, which frequently is a therapeutic challenge. Most conventional diuretics act primarily as saluretics, i.e. they inhibit renal tubular electrolyte reabsorption, which due to osmotic pressure promotes excretion of isotonic fluid. Arginine vasopressin (AVP) via the V(1A) receptor vasoconstricts and via the V(2) receptor promotes water reabsorption in the renal collecting duct by inserting aquaporin-2 water channels into the luminal membrane. Novel V(2) receptor antagonists act as powerful aquaretics, i.e. they excrete free water. We review the pharmacology of non-selective V(1A)/V(2) receptor antagonists and selective V(2) receptor antagonists currently in clinical development.

Hyponatremia in cirrhosis: pathogenesis, clinical significance, and management

Hyponatremia is a frequent complication of advanced cirrhosis related to an impairment in the renal capacity to eliminate solute-free water that causes a retention of water that is disproportionate to the retention of sodium, thus causing a reduction in serum sodium concentration and hypo-osmolality. The main pathogenic factor responsible for hyponatremia is a nonosmotic hypersecretion of arginine vasopressin (or antidiuretic hormone) from the neurohypophysis related to circulatory dysfunction. Hyponatremia in cirrhosis is associated with increased morbidity and mortality. There is evidence suggesting that hyponatremia may affect brain function and predispose to hepatic encephalopathy. Hyponatremia also represents a risk factor for liver transplantation as it is associated with increased frequency of complications and impaired short-term survival after transplantation. The current standard of care based on fluid restriction is unsatisfactory. Currently, a new family of drugs, known as vaptans, which act by antagonizing specifically the effects of arginine vasopressin on the V2 receptors located in the kidney tubules, is being evaluated for their role in the management of hyponatremia. The short-term treatment with vaptans is associated with a marked increase in renal solute-free water excretion and improvement of hyponatremia. Long-term administration of vaptans seems to be effective in maintaining the improvement of serum sodium concentration, but the available information is still limited. Treatment with vaptans represents a novel approach to improving serum sodium concentration in cirrhosis.

Assessment of the efficacy and safety of intravenous conivaptan in euvolemic and hypervolemic hyponatremia

BACKGROUND

Most cases of hyponatremia--serum sodium concentration ([Na+]) < 135 mEq/l (< 135 mM)--are associated with an elevated plasma arginine vasopressin level. This study investigated the efficacy and tolerability of intravenous conivaptan (YM087), a vasopressin V1A/V2-receptor antagonist, in treating euvolemic and hypervolemic hyponatremia.

METHODS

Eighty-four hospitalized patients with euvolemic or hypervolemic hyponatremia (serum [Na+] 115 to < 130 mEq/l) were randomly assigned to receive intravenous placebo or conivaptan administered as a 30-min, 20-mg loading dose followed by a 96-hour infusion of either 40 or 80 mg/day. The primary efficacy measure was change in serum [Na+], measured by the baseline-adjusted area under the [Na+]-time curve. The secondary measures included time from first dose to a confirmed > or = 4 mEq/l serum [Na+] increase, total time patients had serum [Na+] > or = 4 mEq/l higher than baseline, change in serum [Na+] from baseline to the end of treatment, and number of patients with a confirmed > or = 6 mEq/l increase in serum [Na+] or normal [Na+] (> or = 135 mEq/l).

RESULTS

Both conivaptan doses increased area under the [Na+]-time curve during the 4-day treatment (p < 0.0001 vs. placebo). From baseline to the end of treatment, the least-squares mean +/- standard error serum [Na+] increase associated with placebo was 0.8 +/- 0.8 mEq/l; with conivaptan 40 mg/day, 6.3 +/- 0.7 mEq/l; and with conivaptan 80 mg/day, 9.4 +/- 0.8 mEq/l. Conivaptan significantly improved all secondary efficacy measures (p < 0.001 vs. placebo, both doses). Conivaptan was generally well tolerated, although infusion-site reactions led to the withdrawal of 1 (3%) and 4 (15%) of patients given conivaptan 40 and 80 mg/day, respectively.

CONCLUSION

Among patients with euvolemic or hypervolemic hyponatremia, 4-day intravenous infusion of conivaptan 40 mg/day significantly increased serum [Na+] and was well tolerated.