In vitro binding and receptor-mediated activity of terlipressin at vasopressin receptors V1 and V2

A Review of Terlipressin in Hepatorenal Syndrome: Targeting Endothelial Dysfunction and Subsequent Cardiovascular Adverse Events

Hepatorenal syndrome (HRS) is a serious complication of decompensated liver cirrhosis that results in acute kidney injury (AKI). The mortality rate is high. Endothelial dysfunction secondary to liver cirrhosis is a key driver of the development of portal hypertension, which is eventually complicated by ascites and HRS. Ultimately, splanchnic vasodilation and excess gut lymph production result in ascites, low effective arterial blood volume, and maladaptive compensatory mechanisms that contribute to renal hypoperfusion and injury. While the only curative treatment is liver transplantation, vasoconstrictors and albumin have been the mainstay of treatment for candidates who are ineligible or waiting for transplantation. On September 14, 2022, terlipressin, a V1 vasopressin receptor agonist, was approved by the Food and Drug Administration for the treatment of HRS-AKI. In clinical trials, terlipressin plus albumin have been superior to albumin alone and equivocal to noradrenaline plus albumin in renal function improvement. Terlipressin, however, does not improve survival, is costly, and is associated with severe adverse events-including severe cardiac and vascular complications. The aim of this review is to provide an overview of terlipressin pharmacology, adverse events-with a focus on cardiovascular complications-and comparative randomized controlled trials that resulted in the Food and Drug Administration's approval of terlipressin. New literature since its approval and ongoing clinical trials will also be highlighted.

Terlipressin for hepatorenal syndrome

PURPOSE OF REVIEW

The definition and diagnostic criteria of hepatorenal syndrome-acute kidney injury (HRS-AKI) has undergone recent changes. A major vasoconstrictor, terlipressin, has recently been approved as pharmacotherapy for HRS-AKI in the United States. The purpose of this review is to familiarize the readers with these new diagnostic criteria of HRS-AKI, and how best to use terlipressin.

RECENT FINDINGS

Terlipressin is effective either as bolus dosing or continuous infusion and can achieve reversal of HRS-AKI in approximately 40% of patients. Continuous infusion allows lower daily dose with equal efficacy and less side effects but not an approved mode of administration in the United States. Response to terlipressin in the randomized controlled trials was defined as repeat reduction of serum creatinine to less than 1.5 mg/dl. Newer studies will likely require response to treatment to be defined as a repeat serum creatinine to be less than 0.3 mg/dl from baseline. Terlipressin use is associated with ischemic side effects and potential for respiratory failure development.

SUMMARY

Careful patient selection and close monitoring are necessary for its use. Response to terlipressin with HRS-AKI reversal is associated with improved outcomes with better survival and less requirement for renal replacement therapy.

Decreased need for RRT in liver transplant recipients after pretransplant treatment of hepatorenal syndrome-type 1 with terlipressin

Hepatorenal syndrome-acute kidney injury (HRS-AKI), a serious complication of decompensated cirrhosis, has limited therapeutic options and significant morbidity and mortality. Terlipressin improves renal function in some patients with HRS-1, while liver transplantation (LT) is a curative treatment for advanced chronic liver disease. Renal failure post-LT requiring renal replacement therapy (RRT) is a major risk factor for graft and patient survival. A post hoc analysis with a 12-month follow-up of LT recipients from a placebo-controlled trial of terlipressin (CONFIRM; NCT02770716) was conducted to evaluate the need for RRT and overall survival. Patients with HRS-1 were treated with terlipressin plus albumin or placebo plus albumin for up to 14 days. RRT was defined as any type of procedure that replaced kidney function. Outcomes compared between groups included the incidence of HRS-1 reversal, the need for RRT (pretransplant and posttransplant), and overall survival. Of the 300 patients in CONFIRM (terlipressin n = 199; placebo, n = 101), 70 (23%) underwent LT alone (terlipressin, n = 43; placebo, n = 27) and 5 had simultaneous liver-kidney transplant (terlipressin, n = 3, placebo, n = 2). The rate of HRS reversal was significantly higher in the terlipressin group compared with the placebo group (37%, n = 16 vs. 15%, n = 4; p = 0.033). The pretransplant need for RRT was significantly lower among those who received terlipressin ( p = 0.007). The posttransplant need for RRT, at 12 months, was significantly lower among those patients who received terlipressin and were alive at Day 365, compared to placebo ( p = 0.009). Pretransplant treatment with terlipressin plus albumin in patients with HRS-1 decreased the need for RRT pretransplant and posttransplant.

Hepatorenal Syndrome Type 1: Diagnosis and Treatment

Hepatorenal syndrome (HRS) is a feared complication in patients with advanced cirrhosis and is associated with significant morbidity and mortality. While recognized as a distinct physiologic condition for well over one hundred years, a lack of objective diagnostic tests has made the diagnosis one of exclusion. Since 1979, multiple sets of diagnostic criteria have been proposed. Though varying in detail, the principal intent of these criteria is to identify patients with severe, functional acute kidney injury that is unresponsive to volume resuscitation and exclude those with structural injury. However, accurate differential diagnosis remains challenging. Recently, multiple urinary biomarkers of kidney injury, including neutrophil gelatinase-associated lipocalin, have been studied as a means of objectively phenotyping etiologies of acute kidney injury in patients with cirrhosis. Along with markers reflecting tubular functional integrity, including the fractional excretion of sodium, injury markers will likely be incorporated into future diagnostic criteria. Making an accurate diagnosis is critical, as therapeutic options exist for HRS but must be given in a timely manner and only to those patients likely to benefit. Terlipressin, an analog of vasopressin, is the first line of therapy for HRS in much of the world and has recently been approved for use in the United States. Significant questions remain regarding the optimal dosing strategy, metrics for titration, and the potential role of point-of-care ultrasound to help guide concurrent albumin administration.

From past to present to future: Terlipressin and hepatorenal syndrome-acute kidney injury

Hepatorenal syndrome (HRS) is a rare and highly morbid form of kidney injury unique to patients with decompensated cirrhosis. HRS is a physiologic consequence of portal hypertension, leading to a functional kidney injury that can be reversed by restoring effective circulating volume and renal perfusion. While liver transplantation is the only definitive "cure" for HRS, medical management with vasoconstrictors and i.v. albumin is a cornerstone of supportive care. Terlipressin, a V1a receptor agonist that acts on the splanchnic circulation, has been used for many years outside the United States for the treatment of HRS. However, its recent Food and Drug Administration approval has generated new interest in this population, as a new base of prescribers now work to incorporate the drug into clinical practice. In this article, we review HRS pathophysiology and diagnostic criteria, the clinical use of terlipressin and alternative therapies, and identify areas of future research in the space of HRS and kidney injury in cirrhosis.

Hepatorenal Syndrome With Acute Kidney Injury: Diagnosis and Medical Management

OBJECTIVES

To review the current definitions and diagnostic criteria for acute kidney injury (AKI) and type 1 hepatorenal syndrome (HRS) now termed HRS-AKI and discuss the challenges in deciding the most appropriate medication regimens to treat patients with HRS-AKI.

DATA SOURCES

PubMed (inception to April 2023) with bibliographies of retrieved articles searched for additional articles; organizational websites for clinical practice guidelines (CPGs).

STUDY SELECTION AND DATA EXTRACTION

Randomized controlled trials (RCTs) evaluating albumin and vasoconstrictors for HRS-AKI.

DATA SYNTHESIS

A major change in the most recent revision of definitions and diagnostic criteria for HRS-AKI is the elimination of the set cutoff serum creatinine values for AKI. This change should be considered when comparing studies of HRS-AKI over time. Albumin has been administered to both vasoconstrictor treatment and placebo groups in all recent RCTs; however, there has never been a large RCT evaluating a no-albumin group. Most prospective trials comparing a midodrine/octreotide combination or norepinephrine to placebo or terlipressin have enrolled less than 100 patients limiting any conclusions regarding clinically important outcomes. Terlipressin with albumin has shown mixed results for complete HRS-AKI reversal with no reductions in crude mortality but adverse effect concerns involving ischemic and pulmonary events.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Type 1 hepatorenal syndrome with acute kidney injury is a potentially life-threatening syndrome with diagnostic and treatment challenges. Albumin plus a vasoconstrictor has become the routine HRS-AKI treatment even though there has not been a large RCT evaluating a no-albumin group. Terlipressin is the vasoconstrictor of choice for HRS-AKI in current CPGs, but it has adverse effect concerns and, until recently, was not available in the United States.

CONCLUSIONS

In conjunction with changes in the definitions and diagnostic criteria for HRS-AKI, debate continues regarding the optimal therapy for HRS-AKI, particularly considering recent trials demonstrating ischemic and pulmonary adverse events with terlipressin used in combination with albumin.

Hepatorenal Syndrome-Novel Insights into Diagnostics and Treatment

Hepatorenal syndrome (HRS) is a disorder associated with cirrhosis and renal impairment, with portal hypertension as its major underlying cause. Moreover, HRS is the third most common cause of acute kidney injury, thus creating a major public health concern. This review summarizes the available information on the pathophysiological implications of HRS. We discuss pathogenesis associated with HRS. Mechanisms such as dysfunction of the circulatory system, bacterial infection, inflammation, impaired renal autoregulation, circulatory, and others, which have been identified as critical pathways for development of HRS, have become easier to diagnose in recent years. Additionally, relatively recently, renal dysfunction biomarkers have been found indicating renal injury, which are involved in the pathophysiology of HRS. This review also summarizes the available information on the management of HRS, focusing on vasoconstrictive drugs, renal replacement therapy, and liver transplant together with currently being investigated novel therapies. Analyzing new discoveries for the underlying causes of this condition assists the general research to improve understanding of the mechanism of pathophysiology and thus prevention of HRS.

Treatment-Related Cost Analysis of Terlipressin for Adults with Hepatorenal Syndrome with Rapid Reduction in Kidney Function

INTRODUCTION

Hepatorenal syndrome (HRS), a special form of acute kidney failure, is a rare, acute, life-threatening complication of cirrhosis and has a very poor prognosis. Terlipressin (TERLIVAZ®) is the first and only pharmacological treatment approved by Food and Drug Administration (September 2022) to improve kidney function for adults with HRS with rapid reduction in kidney function. We constructed a decision analytic economic model to estimate the cost per complete response/HRS reversal of terlipressin + albumin from a United States hospital perspective.

METHODS

A decision analytic model was developed to estimate the HRS treatment-related cost per response over an HRS hospitalization (assuming 14 days). Patients can experience either HRS reversal (complete response) or no HRS reversal (partial/no response) upon receipt of treatment. The efficacy, safety, and treatment duration data were from published head-to-head randomized international trials. Total treatment cost comprised drug acquisition and treatment-related costs (intensive care unit [ICU], dialysis [intermittent or continuous], pulse oximetry monitoring for terlipressin, and adverse events) sourced from the published literature. Cost per response, defined as the total treatment cost per HRS reversal was estimated for each treatment. The number needed to treat (NNT), defined as the number of patients treated to achieve HRS reversal in 1 additional patient, was estimated.

RESULTS

Cost per response of terlipressin + albumin was lower than midodrine and octreotide + albumin (M&O) (US$85,315 vs. $467,794) and norepinephrine + albumin ($81,614 vs. $139,324). NNT for HRS reversal was 2 patients with terlipressin + albumin vs. M&O + albumin and 4 patients with terlipressin + albumin vs. norepinephrine + albumin, respectively.

CONCLUSIONS

The analysis shows that terlipressin is a cost-effective treatment due to its higher efficacy and administration in the non-ICU setting. Terlipressin is a value-based treatment option for appropriate adults with HRS with rapid reduction in kidney function.

Improving Outcomes in Hepatorenal Syndrome-Acute Kidney Injury With Early Diagnoses and Implementation of Approved Treatment Regimens

Decompensated cirrhosis, defined by the overt manifestations of liver failure and portal hypertension (eg, ascites, hepatic encephalopathy, variceal bleeding), is the inflection point associated with increased morbidity and mortality in chronic liver disease. Acute kidney injury in the setting of cirrhosis (hepatorenal syndrome-acute kidney injury [HRS-AKI]) is a severe and often fatal complication. The goals of treatment of HRS-AKI are to reverse renal failure and prolong survival in these critically ill patients or perhaps to allow the transplant team to complete the pretransplant evaluation and bridge the patient to transplant. Historically, in the United States, standard-of-care treatments for HRS-AKI were chosen by default despite lack of data, off-label use, and suboptimal results. Terlipressin represents the first drug in the United States indicated for the treatment of HRS-AKI. This review provides an up-to-date overview of HRS-AKI, discusses terlipressin and how to incorporate this new treatment into patient care and streamline society guidelines on HRS diagnosis and treatment in a practical way for clinical use, and concludes with a sample order set that highlights the recommendations discussed throughout the supplement.

[Hepatorenal Syndrome]

Hepatorenal syndrome (HRS) is a critical and potentially life-threatening complication of advanced liver disease, including cirrhosis. It is characterized by the development of renal dysfunction in the absence of underlying structural kidney pathology. The pathophysiology of HRS involves complex interactions between systemic and renal hemodynamics, neurohormonal imbalances, and the intricate role of vasoconstrictor substances. Understanding these mechanisms is crucial for the timely identification and management of HRS. The diagnosis of HRS is primarily clinical and relies on specific criteria that consider the exclusion of other causes of renal dysfunction. The management of HRS comprises two main approaches: vasoconstrictor therapy and albumin infusion, which aim to improve renal perfusion and mitigate the hyperdynamic circulation often seen in advanced liver disease. Additionally, strategies such as liver transplantation and renal replacement therapy are essential considerations based on individual patient characteristics and disease severity. This review article provides a comprehensive overview of hepatorenal syndrome, focusing on its pathophysiology, diagnostic criteria, and current management strategies.

Effect of different infusion approaches on safety and efficacy of terlipressin: Current controversies

Terlipressin, a synthetic analog of vasopressin, has been widely used to treat acute variceal bleeding, hepatorenal syndrome, and other complications of cirrhosis. However, among different infusion approaches of terlipressin, its safety and efficacy are also heterogeneous. Previous studies have demonstrated that continuous infusion of terlipressin is more effective with a lower incidence of adverse events than intermittent intravenous infusion. This paper aims to review the relevant literature and summarize the data regarding the safety and effectiveness of different infusion approaches of terlipressin to guide clinical practice.

Partial vasopressin 1a receptor agonism reduces portal hypertension and hyperaldosteronism and induces a powerful diuretic and natriuretic effect in rats with cirrhosis and ascites

The vasopressin system has emerged as a therapeutic focus for lowering portal hypertension and reducing splanchnic vasodilation in patients with refractory ascites. Clinically available vasopressin agonists are limited by preferential selectivity for V1 receptors that also have steep concentration-response curves with potential risks of excess vasoconstriction and/or complete antidiuretic effects. OCE-205 is a novel, selective, partial V1a receptor agonist with mixed agonist/antagonist activity and no V2 receptor activation at therapeutic doses. We carried out two studies assessing the in vivo effects of OCE-205 in different rat models of cirrhosis and ascites. In a carbon tetrachloride rat cirrhosis model, OCE-205 administration produced a marked reduction in portal hypertension and hyperaldosteronism, along with robust diuretic and natriuretic effects. These effects were accompanied by marked decreases in ascites volume, with three of five animals experiencing total mobilization of ascites. There was no evidence of fluid overload or sodium or water retention, confirming OCE-205's lack of V2 receptor activity. In a second, corroborative study using a bile duct ligation rat model of ascites, OCE-205 produced significant decreases in ascites volume and body weight and a significant increase in urine volume versus vehicle. Urine sodium excretion increased significantly after the first administration of OCE-205 relative to vehicle; however, repeat administration over 5 days did not lead to hyponatremia. Thus, in separate in vivo models, the mixed agonist/antagonist OCE-205 demonstrated relevant and expected endpoint findings consistent with its known mechanism of action and in vitro pharmacology without apparent unwanted effects or nonspecific toxicities.

OCE-205 in rats and non-human primates: Pharmacokinetic and pharmacodynamic analysis

Treatment for complications associated with the hemodynamic consequences of decompensated cirrhosis remains suboptimal. Terlipressin, the latest pharmacological management of hepatorenal syndrome-acute kidney injury (HRS-AKI), targets the vasopressin system but has serious side effects. OCE-205 is a novel peptide designed to target the vasopressin receptor system as a mixed V1a agonist/antagonist, resulting in effective partial agonism without V2 agonism. We examined the in vivo pharmacokinetic/pharmacodynamic properties of OCE-205 in healthy rats and cynomolgus monkeys. OCE-205 was administered by IV or SC bolus injection; arginine vasopressin (AVP) or terlipressin were comparators. After IV OCE-205 administration in rats, mean plasma concentration decreased in a mostly linear manner to 2 mg/mL after 120 min, and for SC administration, slowly decreased to ∼50 ng/mL after 300 min. Compared with pre-test values, arterial blood pressure values significantly increased after all OCE-205 doses tested. For monkeys, the concentration after IV OCE-205 administration was mostly linear to 5 ng/mL after 180 min, and for SC administration, ∼3 ng/mL after 480 min. Subcutaneous OCE-205 administration increased mean arterial pressure (MAP) versus baseline, with ΔMAP in OCE-205-treated animals marked and long-lasting while terlipressin induced an increase from baseline in MAP, with negligible ΔMAP, on average, by 150 min after administration in all groups. AVP, but not OCE-205, significantly increased blood lactate concentrations. OCE-205 was well tolerated in adult male rats and cynomolgus monkeys following single-dose bolus administration. The preclinical results of OCE-205, with its demonstrated V1a selective partial agonist activity and potentially tolerable safety profile, suggest its potential utility for treatment of the cardiovascular complications of cirrhosis.

Institutional protocol number

Procedures were approved by the Ferring Research Institute (FRI) Institutional Animal Care and Use Committee (IACUC) on November 27, 2006 under protocol FRI 06-011, and by the Sinclair Research Center IACUC under protocol S11177.

The Effect of Terlipressin on Renal Replacement Therapy in Patients with Hepatorenal Syndrome

Key Points

Hepatorenal syndrome type 1 (HRS-1) is an often fatal, but potentially reversible, kidney failure in patients with decompensated cirrhosis. Treatment with terlipressin in patients with HRS-1 is associated with a reduction in the need for RRT.

Background

Hepatorenal syndrome type 1 (HRS-1)—also known as hepatorenal syndrome-AKI (HRS-AKI)—is a rapidly progressing and usually fatal, but potentially reversible, kidney failure occurring in patients with decompensated cirrhosis. A large proportion of patients with HRS-1 require renal replacement therapy (RRT). Terlipressin demonstrated efficacy in reversing HRS and improving renal function in patients with HRS-1 in three phase III, randomized, clinical trials (RCTs; i.e. , OT-0401, REVERSE, and CONFIRM). However, these RCTs were not designed to evaluate the effect of terlipressin on the requirement of RRT. In this study, the effect of terlipressin on RRT requirements in the pooled phase III patient population was assessed.

Methods

For this retrospective analysis, data from patients who participated in the OT-0401, REVERSE, and CONFIRM studies were integrated in the largest-to-date randomized database (N =608).

Results

The need for RRT was significantly decreased in patients in the terlipressin group versus the placebo group by day 30 (28.1% versus 35.9%, respectively; P = 0.040) and day 60 (30.1% versus 37.9%, respectively; P = 0.045) in the pooled population and also postliver transplantation (LT) at day 60 (20.5% versus 40.3%, respectively; P = 0.008) and day 90 (25.3% versus 43.1%, respectively; P = 0.018). More patients were alive and RRT-free by day 90 in the overall population (36.9% versus 28.5%; P = 0.030) and among patients who received an LT (60.0% versus 39.7%; P = 0.010). Random assignment to receive terlipressin was an independent positive predictor of avoidance of RRT (P = 0.042); while higher baseline serum creatinine (sCr) level and Child-Pugh scores were negatively associated with RRT avoidance (P < 0.001 and P = 0.040, respectively).

Conclusions

Terlipressin decreased the requirement of RRT compared with placebo among patients with HRS-1, including those receiving LT. A lower sCr level at the beginning of therapy was associated with avoidance of RRT.

OCE-205, a Selective V1a Partial Agonist, Reduces Portal Pressure in Rat Models of Portal Hypertension

Purpose

Management of decompensated cirrhosis may include the use of vasoconstrictors that can lead to serious adverse events. OCE-205 was designed as a highly selective V1a receptor partial agonist, intended to have a wider therapeutic window than full vasopressin agonists.

Methods

We aimed to characterize the activity of OCE-205 treatment in two rat models of portal hypertension (PHT). For both models, OCE-205 was administered as a subcutaneous bolus injection. Thirty male Wistar rats were fed a methionine/choline-deficient (MCD) diet to model PHT. Animals received OCE-205 (10, 25, 100, or 500 µg/kg) or intra-arterial terlipressin (100 µg/kg). In a more severe model of PHT, 11 male Sprague Dawley rats had the common bile duct surgically ligated (BDL) and received OCE-205. Portal pressure (PP) and mean arterial pressure (MAP) were measured.

Results

For PP in the MCD model, MAP increased while PP decreased in rats treated with OCE-205 or terlipressin; the peak changes to MAP were 14.7 and 33.5 mmHg, respectively. Changes in MAP began to plateau after 10 min in the OCE-205 groups, whereas in the terlipressin group, MAP rapidly increased and peaked after 20 min. Across all treatment groups in the BDL model, a dose-related decrease from baseline in PP was observed following OCE-205, plateauing as the dose increased. In all treatment groups, PP change remained negative throughout the 30-min testing period. In both PHT rat models, a reduction in PP was coupled to an increase in MAP, with both plateauing in dose-response curves.

Conclusion

Data support OCE-205 as a promising candidate for further development.

Institutional Protocol Number

Procedures were approved by the Ferring Research Institute (FRI) Institutional Animal Care and Use Committee on July 13, 2011, under protocol FRI-07-0002.

Role of Terlipressin in Patients With Hepatorenal Syndrome-Acute Kidney Injury Admitted to the ICU: A Substudy of the CONFIRM Trial

This study assessed the potential advantages of treating hepatorenal syndrome-acute kidney injury (HRS-AKI) with terlipressin versus placebo in the ICU setting.

DESIGN

Patients were randomly assigned in a 2:1 ratio to receive terlipressin or placebo for up to 14 days.

SETTING

A retrospective analysis of data from the phase III CONFIRM study.

PARTICIPANTS

Adult patients with HRS-AKI admitted to the ICU.

MAIN OUTCOMES AND MEASURES

In this substudy, we evaluated outcomes of the ICU stay and the need for organ support, including renal replacement therapy (RRT).

RESULTS

Among 300 patients with HRS-AKI from the CONFIRM study, 45 were treated in the ICU (terlipressin, 31/199 [16%]; placebo, 14/101 [14%]). On ICU admission, baseline demographics were similar across treatment arms, including severity of liver dysfunction. Among patients alive at the end of the ICU stay, those randomized to terlipressin had a significantly shorter median length of ICU stay than placebo (4 vs 11 d; p < 0.001). Terlipressin-treated patients had a significantly larger improvement in renal function from baseline versus placebo (-0.7 vs +0.2 mg/dL; p = 0.001), including when accounting for the interaction between treatment and day-of-patient-admission to the ICU (-0.7 vs +0.9 mg/dL; p < 0.001). Cumulative requirement for RRT through day 90 was improved in the terlipressin arm versus placebo (10/31 [32%] vs 8/14 [57%]; p = 0.12), although not significantly. Of 13 patients who received a liver transplant, five out of five (100%) in the placebo arm needed RRT through day 90 versus five out of eight (63%) in the terlipressin arm.

CONCLUSIONS

In this subanalysis of CONFIRM, patients admitted to the ICU with HRS-AKI who received terlipressin were more likely to achieve renal function improvement, based on serum creatinine changes by the end of treatment, and had significantly shorter lengths of ICU stay than patients randomized to the placebo arm.

Arginine vasopressin hormone receptor antagonists in experimental autoimmune encephalomyelitis rodent models: A new approach for human multiple sclerosis treatment

Multiple sclerosis (MS) is a chronic demyelinating and neurodegenerative disease that affects the central nervous system. MS is a heterogeneous disorder of multiple factors that are mainly associated with the immune system including the breakdown of the blood-brain and spinal cord barriers induced by T cells, B cells, antigen presenting cells, and immune components such as chemokines and pro-inflammatory cytokines. The incidence of MS has been increasing worldwide recently, and most therapies related to its treatment are associated with the development of several secondary effects, such as headaches, hepatotoxicity, leukopenia, and some types of cancer; therefore, the search for an effective treatment is ongoing. The use of animal models of MS continues to be an important option for extrapolating new treatments. Experimental autoimmune encephalomyelitis (EAE) replicates the several pathophysiological features of MS development and clinical signs, to obtain a potential treatment for MS in humans and improve the disease prognosis. Currently, the exploration of neuro-immune-endocrine interactions represents a highlight of interest in the treatment of immune disorders. The arginine vasopressin hormone (AVP) is involved in the increase in blood−brain barrier permeability, inducing the development and aggressiveness of the disease in the EAE model, whereas its deficiency improves the clinical signs of the disease. Therefore, this present review discussed on the use of conivaptan a blocker of AVP receptors type 1a and type 2 (V1a and V2 AVP) in the modulation of immune response without completely depleting its activity, minimizing the adverse effects associated with the conventional therapies becoming a potential therapeutic target in the treatment of patients with multiple sclerosis.

Respiratory events with terlipressin and albumin in hepatorenal syndrome: A review and clinical guidance

Hepatorenal syndrome-acute kidney injury (HRS-AKI) is a serious complication of severe liver disease with a clinically poor prognosis. Supportive care using vasoconstrictors and intravenous albumin are the current mainstays of therapy. Terlipressin is an efficacious vasoconstrictor that has been used for 2 decades as the first-line treatment for HRS-AKI in Europe and has demonstrated greater efficacy in improving renal function compared to placebo and other vasoconstrictors. One of the challenges associated with terlipressin use is monitoring and mitigating serious adverse events, specifically adverse respiratory events, which were noted in a subset of patients in the recently published CONFIRM trial, the largest randomized trial examining terlipressin use for HRS-AKI. In this article, we review terlipressin's pharmacology, hypothesize how its mechanism contributes to the risk of respiratory compromise and propose strategies that will decrease the frequency of these events by rationally selecting patients at lower risk for these events.

Practice guidance for the use of terlipressin for liver cirrhosis-related complications

Background

Liver cirrhosis is a major global health burden worldwide due to its high risk of morbidity and mortality. Role of terlipressin for the management of liver cirrhosis-related complications has been recognized during recent years. This article aims to develop evidence-based clinical practice guidance on the use of terlipressin for liver cirrhosis-related complications.

Methods

Hepatobiliary Study Group of the Chinese Society of Gastroenterology of the Chinese Medical Association and Hepatology Committee of the Chinese Research Hospital Association have invited gastroenterologists, hepatologists, infectious disease specialists, surgeons, and clinical pharmacists to formulate the clinical practice guidance based on comprehensive literature review and experts' clinical experiences.

Results

Overall, 10 major guidance statements regarding efficacy and safety of terlipressin in liver cirrhosis were proposed. Terlipressin can be beneficial for the management of cirrhotic patients with acute variceal bleeding and hepatorenal syndrome (HRS). However, the evidence regarding the use of terlipressin in cirrhotic patients with ascites, post-paracentesis circulatory dysfunction, and bacterial infections and in those undergoing hepatic resection and liver transplantation remains insufficient. Terlipressin-related adverse events, mainly including gastrointestinal symptoms, electrolyte disturbance, and cardiovascular and respiratory adverse events, should be closely monitored.

Conclusion

The current clinical practice guidance supports the use of terlipressin for gastroesophageal variceal bleeding and HRS in liver cirrhosis. High-quality studies are needed to further clarify its potential effects in other liver cirrhosis-related complications.

Pharmacokinetic and pharmacodynamic analyses of terlipressin in patients with hepatorenal syndrome

The objective of this population pharmacokinetics (PK) analysis was to characterize the PK of terlipressin and its active metabolite, lysine-vasopressin (L-VP), in patients with hepatorenal syndrome (HRS), following intravenous administration of terlipressin 1 mg to 2 mg every 6 h. Sparse PK samples from 69 patients with HRS who participated in terlipressin phase 3 clinical studies were used for model development. In addition, mean arterial pressure (MAP) and heart rate (HR) from 40 patients with HRS were available to explore the relationship between terlipressin and L-VP plasma concentrations and pharmacodynamic (PD) response. A two-compartment model with first-order elimination adequately described the PK of terlipressin. L-VP was well characterized as the active metabolite of terlipressin by a one-compartment model with first-order elimination. The population PK modeling results showed that the estimated clearances for terlipressin and L-VP are 27.4 L/h and 318 L/h, respectively, for a typical patient with a body weight of 86 kg. Body weight was identified as the only covariate for the clearance of terlipressin. However, simulation suggested that body weight had no clinically meaningful effects on the exposure of L-VP through terlipressin. Therefore, no weight-based dose is needed for terlipressin to treat HRS patients. PD response, change in MAP, and HR were well correlated to L-VP concentrations; compared with baseline values, the estimated maximum decrease in HR would be 10.6 bpm and the estimated maximum increase in MAP would be 16.2 mm Hg.

Vasopressin and Its Analogues: From Natural Hormones to Multitasking Peptides

Human neurohormone vasopressin (AVP) is synthesized in overlapping regions in the hypothalamus. It is mainly known for its vasoconstricting abilities, and it is responsible for the regulation of plasma osmolality by maintaining fluid homeostasis. Over years, many attempts have been made to modify this hormone and find AVP analogues with different pharmacological profiles that could overcome its limitations. Non-peptide AVP analogues with low molecular weight presented good affinity to AVP receptors. Natural peptide counterparts, found in animals, are successfully applied as therapeutics; for instance, lypressin used in treatment of diabetes insipidus. Synthetic peptide analogues compensate for the shortcomings of AVP. Desmopressin is more resistant to proteolysis and presents mainly antidiuretic effects, while terlipressin is a long-acting AVP analogue and a drug recommended in the treatment of varicose bleeding in patients with liver cirrhosis. Recently published results on diverse applications of AVP analogues in medicinal practice, including potential lypressin, terlipressin and ornipressin in the treatment of SARS-CoV-2, are discussed.

Hepatorenal Syndrome Type 1: From Diagnosis Ascertainment to Goal-Oriented Pharmacologic Therapy

Hepatorenal syndrome type 1 (HRS-1) is a serious form of AKI that affects individuals with advanced cirrhosis with ascites. Prompt and accurate diagnosis is essential for effective implementation of therapeutic measures that can favorably alter its clinical course. Despite decades of investigation, HRS-1 continues to be primarily a diagnosis of exclusion. Although the diagnostic criteria dictated by the International Club of Ascites provide a useful framework to approach the diagnosis of HRS-1, they do not fully reflect the complexity of clinical scenarios that is often encountered in patients with cirrhosis and AKI. Thus, diagnostic uncertainty is often faced. In particular, the distinction between HRS-1 and acute tubular injury is challenging with the currently available clinical tools. Because treatment of HRS-1 differs from that of acute tubular injury, distinguishing these two causes of AKI has direct implications in management. Therefore, the use of the International Club of Ascites criteria should be enhanced with a more individualized approach and attention to the other phenotypic aspects of HRS-1 and other types of AKI. Liver transplantation is the most effective treatment for HRS-1, but it is only available to a small fraction of the affected patients worldwide. Thus, pharmacologic therapy is necessary. Vasoconstrictors aimed to increase mean arterial pressure constitute the most effective approach. Administration of intravenous albumin is an established co-adjuvant therapy. However, the risk for fluid overload in patients with cirrhosis with AKI is not negligible, and interventions intended to expand or remove volume should be tailored to the specific needs of the patient. Norepinephrine and terlipressin are the most effective vasoconstrictors, and their use should be determined by availability, ease of administration, and attention to optimal risk-benefit balance for each clinical scenario.

In-hospital mortality of hepatorenal syndrome in the United States: Nationwide inpatient sample

BACKGROUND

Hepatorenal syndrome (HRS) is a life-threatening condition among patients with advanced liver disease. Data trends specific to hospital mortality and hospital admission resource utilization for HRS remain limited.

AIM

To assess the temporal trend in mortality and identify the predictors for mortality among hospital admissions for HRS in the United States.

METHODS

We used the National Inpatient Sample database to identify an unweighted sample of 4938 hospital admissions for HRS from 2005 to 2014 (weighted sample of 23973 admissions). The primary outcomes were temporal trends in mortality as well as predictors for hospital mortality. We estimated odds ratios from multi-level mixed effect logistic regression to identify patient characteristics and treatments associated with hospital mortality.

RESULTS

Overall hospital mortality was 32%. Hospital mortality decreased from 44% in 2005 to 24% in 2014 (P < 0.001), while there was an increase in the rate of liver transplantation (P = 0.02), renal replacement therapy (P < 0.001), length of hospital stay (P < 0.001), and hospitalization cost (P < 0.001). On multivariable analysis, older age, alcohol use, coagulopathy, neurological disorder, and need for mechanical ventilation predicted higher hospital mortality, whereas liver transplantation, transjugular intrahepatic portosystemic shunt, and abdominal paracentesis were associated with lower hospital mortality.

CONCLUSION

Although there was an increase in resource utilizations, hospital mortality among patients admitted for HRS significantly improved. Several predictors for hospital mortality were identified.

A Review for the Practicing Clinician: Hepatorenal Syndrome, a Form of Acute Kidney Injury, in Patients with Cirrhosis

The hepatorenal syndrome type of acute kidney injury (HRS-AKI), formerly known as type 1 hepatorenal syndrome, is a rapidly progressing renal failure that occurs in many patients with advanced cirrhosis and ascites. Accumulating evidence has led to a recent evolution of diagnostic criteria for this serious complication of end-stage liver disease. The aim of this review is to provide an overview of disease-related characteristics and therapeutic management of patients with HRS-AKI. Relevant literature was compiled to support discussion of the pathophysiology, diagnosis, prognosis, associated conditions, prevention, treatment, and management of HRS-AKI. Onset of HRS-AKI is characterized by sudden severe renal vasoconstriction, leading to an acute reduction in glomerular filtration rate and rapid, potentially life-threatening, renal deterioration. Although our understanding of disease pathophysiology continues to evolve, etiology of HRS-AKI likely involves systemic hemodynamic changes caused by liver disease, inflammation, and damage to renal parenchyma. There is currently no gold standard for diagnosis, which typically involves a clinical workup, abdominal imaging, and laboratory assessments. The current consensus definition of HRS-AKI includes proposed diagnostic criteria based on changes in serum creatinine levels tailored for high sensitivity, and rapid detection to accelerate diagnosis and treatment initiation. The only potential cure for HRS-AKI is liver transplantation; however, vasoconstrictive agents and other supportive measures are used as needed to help maintain survival for patients who are awaiting or are ineligible for transplantation. The severity of HRS-AKI, complex pathology, limited treatment options, and range of associated conditions pose significant challenges for both patients and care providers.

Terlipressin and the Treatment of Hepatorenal Syndrome: How the CONFIRM Trial Moves the Story Forward

Hepatorenal syndrome (HRS) is a form of acute kidney injury occurring in patients with advanced cirrhosis and is associated with significant morbidity and mortality. The pathophysiology underlying HRS begins with increasing portal pressures leading to the release of vasodilatory substances which result in pooling blood in the splanchnic system and a corresponding reduction in effective circulating volume. Compensatory activation of the sympathetic nervous system, renin-angiotensin-aldosterone system and release of arginine vasopressin serve to defend mean arterial pressure but at the cost of severe constriction of the renal vasculature, leading to a progressive, often fulminant form of AKI. While there are no approved treatments for HRS in the United States, multiple countries, including much of Europe, utilize terlipressin, a synthetic vasopressin analogue, as first-line therapy. The recently published CONFIRM trial, the third randomized trial based in North America evaluating terlipressin, met its primary endpoint, showing greater rates of HRS reversal in the terlipressin arm. However, due to concerns about apparent increased rates of respiratory adverse events and a lack of evidence for mortality benefit, terlipressin was not approved by the Food and Drug Administration (FDA). In this Perspective, we explore the history of regulatory approval for terlipressin in the United States, examine the results from CONFIRM and the concerns they raised and consider the future role of terlipressin in this critical clinical area of continued unmet need.

A Review of Hepatorenal Syndrome

The development of acute kidney injury (AKI) is one of the most frequent complications in patients with cirrhosis. AKI due to volume depletion is the most common etiology and hepatorenal syndrome (HRS) is the second most common cause of AKI in these patients. HRS is the extreme form of kidney injury in patients with cirrhosis, which is caused due to a reduction in renal blood flow unresponsive to volume expansion. The literature involving HRS is rapidly evolving and newer tests and updated definitions have been proposed which allows timely identification and treatment. Here, we will discuss the definition, pathophysiology, prevention, diagnosis, and treatment of HRS.

Recent advances in the understanding and management of hepatorenal syndrome

Renal dysfunction occurs frequently in hospitalized patients with advanced chronic liver disease (ACLD)/cirrhosis and has profound prognostic implications. In ACLD patients with ascites, hepatorenal syndrome (HRS) may result from circulatory dysfunction that leads to reduced kidney perfusion and glomerular filtration rate (in the absence of structural kidney damage). The traditional subclassification of HRS has recently been replaced by acute kidney injury (AKI) type of HRS (HRS-AKI) and non-AKI type of HRS (HRS-NAKI), replacing the terms “HRS type 1” and “HRS type 2”, respectively. Importantly, the concept of absolute serum creatinine (sCr) cutoffs for diagnosing HRS was partly abandoned and short term sCr dynamics now may suffice for AKI diagnosis, which facilitates early treatment initiation that may prevent the progression to HRS-AKI or increase the chances of AKI/HRS-AKI reversal. Recent randomized controlled trials have established (a) the efficacy of (long-term) albumin in the prevention of complications of ascites (including HRS-AKI), (b) the benefits of transjugular intrahepatic portosystemic shunt placement in patients with recurrent ascites, and (c) the superiority of terlipressin over noradrenaline for the treatment of HRS-AKI in the context of acute-on-chronic liver failure. This review article aims to summarize recent advances in the understanding and management of HRS.

Management of Cirrhotic Ascites under the Add-on Administration of Tolvaptan

Tolvaptan is a recently available diuretic that blocks arginine vasopressin receptor 2 in the renal collecting duct. Its diuretic mechanism involves selective water reabsorption by affecting the water reabsorption receptor aquaporin 2. Given that liver cirrhosis patients exhibit hyponatremia due to their pseudo-aldosteronism and usage of natriuretic agents, a sodium maintaining agent, such as tolvaptan, is physiologically preferable. However, large scale studies indicating the patients for whom this would be effective and describing management under its use have been insufficient. The appropriate management of cirrhosis patients treated with tolvaptan should be investigated. In the present review, we collected articles investigating the effectiveness of tolvaptan and factors associated with survival and summarized their management reports. Earlier administration of tolvaptan before increasing the doses of natriuretic agents is recommended because this may preserve effective arterial blood volume.

Terlipressin plus Albumin for the Treatment of Type 1 Hepatorenal Syndrome

BACKGROUND

The vasoconstrictor terlipressin is used for type 1 hepatorenal syndrome (HRS-1) in many parts of the world and is part of the clinical practice guidelines in Europe.

METHODS

We conducted a phase 3 trial to confirm the efficacy and safety of terlipressin plus albumin in adults with HRS-1. The patients were randomly assigned in a 2:1 ratio to receive terlipressin or placebo for up to 14 days; in both groups, concomitant use of albumin was strongly recommended. The primary end point was verified reversal of HRS, defined as two consecutive serum creatinine measurements of 1.5 mg per deciliter or less at least 2 hours apart and survival without renal-replacement therapy for at least 10 days after the completion of treatment. Four prespecified secondary end points were analyzed with the Hochberg procedure to account for multiple comparisons.

RESULTS

A total of 300 patients underwent randomization - 199 were assigned to the terlipressin group and 101 to the placebo group. Verified reversal of HRS was reported in 63 patients (32%) in the terlipressin group and 17 patients (17%) in the placebo group (P = 0.006). With respect to the prespecified secondary end points, HRS reversal, defined as any serum creatinine level of 1.5 mg per deciliter or less during the first 14 days, was reported in 78 patients (39%) in the terlipressin group and 18 (18%) in the placebo group (P<0.001); HRS reversal without renal-replacement therapy by day 30, in 68 (34%) and 17 (17%), respectively (P = 0.001); HRS reversal among patients with systemic inflammatory response syndrome (84 patients in the terlipressin group and 48 patients in the placebo group), in 31 (37%) and 3 (6%), respectively (P<0.001); and verified reversal of HRS without recurrence by day 30, in 52 (26%) and 17 (17%), respectively (P = 0.08). At day 90, liver transplantations had been performed in 46 patients (23%) in the terlipressin group and 29 patients (29%) in the placebo group, and death occurred in 101 (51%) and 45 (45%), respectively. More adverse events, including abdominal pain, nausea, diarrhea, and respiratory failure, occurred with terlipressin than with placebo. Death within 90 days due to respiratory disorders occurred in 22 patients (11%) in the terlipressin group and 2 patients (2%) in the placebo group.

CONCLUSIONS

In this trial involving adults with cirrhosis and HRS-1, terlipressin was more effective than placebo in improving renal function but was associated with serious adverse events, including respiratory failure. (Funded by Mallinckrodt Pharmaceuticals; CONFIRM ClinicalTrials.gov number, NCT02770716.).

The Biology of Vasopressin

Vasopressins are evolutionarily conserved peptide hormones. Mammalian vasopressin functions systemically as an antidiuretic and regulator of blood and cardiac flow essential for adapting to terrestrial environments. Moreover, vasopressin acts centrally as a neurohormone involved in social and parental behavior and stress response. Vasopressin synthesis in several cell types, storage in intracellular vesicles, and release in response to physiological stimuli are highly regulated and mediated by three distinct G protein coupled receptors. Other receptors may bind or cross-bind vasopressin. Vasopressin is regulated spatially and temporally through transcriptional and post-transcriptional mechanisms, sex, tissue, and cell-specific receptor expression. Anomalies of vasopressin signaling have been observed in polycystic kidney disease, chronic heart failure, and neuropsychiatric conditions. Growing knowledge of the central biological roles of vasopressin has enabled pharmacological advances to treat these conditions by targeting defective systemic or central pathways utilizing specific agonists and antagonists.

High expression of a vascular stricture-related marker is predictive of an early response to tolvaptan, and a low fractional excretion of sodium is predictive of a poor long-term survival after tolvaptan administration for liver cirrhosis

AIM

Tolvaptan is a newly available diuretic that has a specific function in water reabsorption inhibition. Given that spironolactone or furosemide induces the aggravation of cirrhotic hyponatremia and dehydration, tolvaptan affects the management strategy of liver cirrhosis. Representative predictive markers of its response include renal function-related markers such as urea nitrogen or creatinine. However, vascular function-related markers have not been well investigated. We investigated the effect of the vascular function-related marker asymmetric dimethylarginine (ADMA) and the effective arterial blood volume (EABV) marker, fractional excretion of sodium (FENa), on the early tolvaptan response and survival in liver cirrhosis.

METHODS

We prospectively recruited 49 patients who required add-on tolvaptan for refractory ascites or edema. Laboratory data were obtained immediately before and 1 day after tolvaptan administration. Patients exhibiting >1.5 kg weight loss after 1 week were categorized as early responders to tolvaptan. Patients were followed for a median of 200 days and were assessed for survival.

RESULTS

Early responders showed lower creatinine levels (<1.0 mg/dL), and higher ADMA levels (≥0.61 nmol/mL) than others in a multivariate analysis. Patients with a shorter survival were positive for hepatocellular carcinoma and had a low FENa (<0.35%).

CONCLUSION

Early responders showed higher ADMA levels reflecting vascular stricture, suggesting that higher vascular tonus is required for a tolvaptan early response. Patients with a shorter survival showed a lower FENa, reflecting a lower EABV and suggesting that adequate EABV is required for the prolonged survival after tolvaptan administration.

Hepatorenal syndrome: pathophysiology, diagnosis, and management

Hepatorenal syndrome (HRS), the extreme manifestation of renal impairment in patients with cirrhosis, is characterized by reduction in renal blood flow and glomerular filtration rate. Hepatorenal syndrome is diagnosed when kidney function is reduced but evidence of intrinsic kidney disease, such as hematuria, proteinuria, or abnormal kidney ultrasonography, is absent. Unlike other causes of acute kidney injury (AKI), hepatorenal syndrome results from functional changes in the renal circulation and is potentially reversible with liver transplantation or vasoconstrictor drugs. Two forms of hepatorenal syndrome are recognized depending on the acuity and progression of kidney injury. The first represents an acute impairment of kidney function, HRS-AKI, whereas the second represents a more chronic kidney dysfunction, HRS-CKD (chronic kidney disease). In this review, we provide critical insight into the definition, pathophysiology, diagnosis, and management of hepatorenal syndrome.

Angiotensin II and Vasopressin for Vasodilatory Shock: A Critical Appraisal of Catecholamine-Sparing Strategies

Vasodilatory shock is a serious medical condition that increases the morbidity and mortality of perioperative and critically ill patients. Norepinephrine is an established first-line therapy for this condition, but at high doses, it may lead to diminishing returns. Oftentimes, secondary noncatecholamine agents are required in those whose hypotension persists. Angiotensin II and vasopressin are both noncatecholamine agents available for the treatment of hypotension in vasodilatory shock. They have distinct modes of action and unique pharmacologic properties when compared to norepinephrine. Angiotensin II and vasopressin have shown promise in certain subsets of the population, such as those with acute kidney injury, high Acute Physiology and Chronic Health Evaluation II scores, or those receiving cardiac surgery. Any benefit from these drugs must be weighed against the risks, as overall mortality has not been shown to decrease mortality in the general population. The aims of this narrative review are to provide insight into the historical use of noncatecholamine vasopressors and to compare and contrast their unique modes of action, physiologic rationale for administration, efficacy, and safety profiles.

Reappraising the spectrum of AKI and hepatorenal syndrome in patients with cirrhosis

The occurrence of acute kidney injury (AKI) in patients with end-stage liver disease constitutes one of the most challenging clinical scenarios in in-hospital and critical care medicine. Hepatorenal syndrome type 1 (HRS-1), which is a specific type of AKI that occurs in the context of advanced cirrhosis and portal hypertension, is associated with particularly high mortality. The pathogenesis of HRS-1 is largely viewed as a functional derangement that ultimately affects renal vasculature tone. However, new insights suggest that non-haemodynamic tubulo-toxic factors, such as endotoxins and bile acids, might mediate parenchymal renal injury in patients with cirrhosis, suggesting that concurrent mechanisms, including those traditionally associated with HRS-1 and non-traditional factors, might contribute to the development of AKI in patients with cirrhosis. Moreover, histological evidence of morphological abnormalities in the kidneys of patients with cirrhosis and renal dysfunction has prompted the functional nature of HRS-1 to be re-examined. From a clinical perspective, a diagnosis of HRS-1 guides utilization of vasoconstrictive therapy and decisions regarding renal replacement therapy. Patients with cirrhosis are at risk of AKI owing to a wide range of factors. However, the tools currently available to ascertain the diagnosis of HRS-1 and guide therapy are suboptimal. Short of liver transplantation, goal-directed haemodynamically targeted pharmacotherapy remains the cornerstone of treatment for this condition; improved understanding of the underlying pathogenic mechanisms might lead to better clinical outcomes. Here, we examine our current understanding of the pathophysiology of HRS-1 and existing challenges in its diagnosis and treatment.