Evaluation of the efficacy and safety of flumazenil in the treatment of portal systemic encephalopathy: a double blind, randomised, placebo controlled multicentre study

Non-Lactulose Medication Therapies for the Management of Hepatic Encephalopathy: A Literature Review

OBJECTIVE

The most appropriate medication regimen to mitigate the consequences hepatic encephalopathy remains inconclusive. This review seeks to serve as a reference for clinicians to help guide therapy decisions with regard to hepatic encephalopathy.

METHODS

A comprehensive literature review between August 2018 and April 2019 was accomplished with the assistance of a medical librarian. Sources of literature review include PubMed, MEDLINE, SCOPUS, ProQuest Central, CINAHL, and ProQuest Dissertations. The authors selected randomized clinical and double-blind cross-over trials evaluating probiotics, zinc, polyethylene glycol, rifaximin, and flumazenil. Sixteen clinical trials are discussed in this review. Pertinent safety, efficacy, and statistical and clinical outcomes are summarized by the authors.

CONCLUSIONS

The most appropriate regimen to mitigate the consequences of hepatic encephalopathy remains elusive; however, the agents discussed within this review offer alternative options for patients unresponsive to or intolerant of traditional lactulose therapy. This review seeks to serve as a repository for relevant clinical trials, and as a reference for clinicians to help guide therapy decisions.

Flumazenil versus placebo or no intervention for people with cirrhosis and hepatic encephalopathy

BACKGROUND

Hepatic encephalopathy is a common complication of cirrhosis which results in poor brain functioning. The spectrum of changes associated with hepatic encephalopathy ranges from the clinically 'indiscernible' or minimal hepatic encephalopathy to the clinically 'obvious' or overt hepatic encephalopathy. Flumazenil is a synthetic benzodiazepine antagonist with high affinity for the central benzodiazepine recognition site. Flumazenil may benefit people with hepatic encephalopathy through an indirect negative allosteric modulatory effect on gamma-aminobutyric acid receptor function. The previous version of this review, which included 13 randomised clinical trials, found no effect of flumazenil on all-cause mortality, based on an analysis of 10 randomised clinical trials, but found a beneficial effect on hepatic encephalopathy, based on an analysis of eight randomised clinical trials.

OBJECTIVES

To evaluate the beneficial and harmful effects of flumazenil versus placebo or no intervention for people with cirrhosis and hepatic encephalopathy.

SEARCH METHODS

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, and LILACS; meeting and conference proceedings; and bibliographies in May 2017.

SELECTION CRITERIA

We included randomised clinical trials regardless of publication status, blinding, or language in the analyses of benefits and harms, and observational studies in the assessment of harms.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data independently. We undertook meta-analyses and presented results using risk ratios (RR) with 95% confidence intervals (CI) and I2 values as a marker of heterogeneity. We assessed bias control using the Cochrane Hepato-Biliary Group domains; determined the quality of the evidence using GRADE; evaluated the risk of small-study effects in regression analyses; and conducted trial sequential, subgroup, and sensitivity analyses.

MAIN RESULTS

We identified 14 eligible randomised clinical trials with 867 participants, the majority of whom had an acute episode of overt hepatic encephalopathy. In addition, we identified one ongoing randomised clinical trial. We were unable to gather outcome data from two randomised clinical trials with 25 participants. Thus, our analyses include 842 participants from 12 randomised clinical trials comparing flumazenil versus placebo. We classified one randomised clinical trial at low risk of bias in the overall assessment and the remaining randomised clinical trials at high risk of bias. The duration of follow-up ranged from a few minutes to two weeks, but it was less than one day in the majority of the trials.In total, 32/433 (7.4%) participants allocated to flumazenil versus 38/409 (9.3%) participants allocated to placebo died (RR 0.75, 95% CI 0.48 to 1.16; 11 randomised clinical trials; low quality evidence). The Trial Sequential Analysis and the one randomised clinical trial assessed as low risk of bias (RR 0.76, 95% CI 0.37 to 1.53) found no beneficial or harmful effects of flumazenil on all-cause mortality. The methods used to evaluate hepatic encephalopathy included several different clinical scales, electrophysiological variables, and psychometric tests. Flumazenil was associated with a beneficial effect on hepatic encephalopathy when including all randomised clinical trials (RR 0.75, 95% CI 0.71 to 0.80; 824 participants; nine randomised clinical trials; low quality evidence), or just the trial at low risk of bias (RR 0.78, 95% CI 0.72 to 0.84; 527 participants). The Trial Sequential Analysis supported a beneficial effect of flumazenil on hepatic encephalopathy. The randomised clinical trials included little information about causes of death and little information on non-fatal serious adverse events.

AUTHORS' CONCLUSIONS

We found low quality evidence suggesting a short-term beneficial effect of flumazenil on hepatic encephalopathy in people with cirrhosis, but no evidence of an effect on all-cause mortality. Additional evidence from large, high quality randomised clinical trials is needed to evaluate the potential benefits and harms of flumazenil in people with cirrhosis and hepatic encephalopathy.

Flumazenil versus placebo or no intervention for people with cirrhosis and hepatic encephalopathy

BACKGROUND

Hepatic encephalopathy is a common complication of cirrhosis which results in poor brain functioning. The spectrum of changes associated with hepatic encephalopathy ranges from the clinically 'indiscernible' or minimal hepatic encephalopathy to the clinically 'obvious' or overt hepatic encephalopathy. Flumazenil is a synthetic benzodiazepine antagonist with high affinity for the central benzodiazepine recognition site. Flumazenil may benefit people with hepatic encephalopathy through an indirect negative allosteric modulatory effect on gamma-aminobutyric acid receptor function. The previous version of this review, which included 13 randomised clinical trials, found no effect of flumazenil on all-cause mortality, based on an analysis of 10 randomised clinical trials, but found a beneficial effect on hepatic encephalopathy, based on an analysis of eight randomised clinical trials.

OBJECTIVES

To evaluate the beneficial and harmful effects of flumazenil versus placebo or no intervention for people with cirrhosis and hepatic encephalopathy.

SEARCH METHODS

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, and LILACS; meeting and conference proceedings; and bibliographies in May 2017.

SELECTION CRITERIA

We included randomised clinical trials regardless of publication status, blinding, or language in the analyses of benefits and harms, and observational studies in the assessment of harms.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data independently. We undertook meta-analyses and presented results using risk ratios (RR) with 95% confidence intervals (CI) and I2 values as a marker of heterogeneity. We assessed bias control using the Cochrane Hepato-Biliary Group domains; determined the quality of the evidence using GRADE; evaluated the risk of small-study effects in regression analyses; and conducted trial sequential, subgroup, and sensitivity analyses.

MAIN RESULTS

We identified 14 eligible randomised clinical trials with 867 participants, the majority of whom had an acute episode of overt hepatic encephalopathy. In addition, we identified one ongoing randomised clinical trial. We were unable to gather outcome data from 2 randomised clinical trials with 25 participants. Thus, our analyses include 842 participants from 12 randomised clinical trials comparing flumazenil versus placebo. We classified one randomised clinical trial at low risk of bias in the overall assessment and the remaining randomised clinical trials at high risk of bias. The duration of follow-up ranged from a few minutes to two weeks, but it was less than one day in the majority of the trials.In total, 32/433 (7.4%) participants allocated to flumazenil versus 38/409 (9.3%) participants allocated to placebo died (RR 0.75, 95% CI 0.48 to 1.16; 11 randomised clinical trials; low quality evidence). The Trial Sequential Analysis and the one randomised clinical trial assessed as low risk of bias (RR 0.76, 95% CI 0.37 to 1.53) found no beneficial or harmful effects of flumazenil on all-cause mortality. The methods used to evaluate hepatic encephalopathy included several different clinical scales, electrophysiological variables, and psychometric tests. Flumazenil was associated with a beneficial effect on hepatic encephalopathy when including all randomised clinical trials (RR 0.75, 95% CI 0.71 to 0.80; 824 participants; 9 randomised clinical trials; low quality evidence), or just the trial at low risk of bias (RR 0.78, 95% CI 0.72 to 0.84; 527 participants). The Trial Sequential Analysis supported a beneficial effect of flumazenil on hepatic encephalopathy. The randomised clinical trials included little information about causes of death and little information on non-fatal serious adverse events.

AUTHORS' CONCLUSIONS

We found low quality evidence suggesting a short-term beneficial effect of flumazenil on hepatic encephalopathy in people with cirrhosis, but no evidence of an effect on all-cause mortality. Additional evidence from large, high quality randomised clinical trials is needed to evaluate the potential benefits and harms of flumazenil in people with cirrhosis and hepatic encephalopathy.

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.

Hepatic encephalopathy in alcoholic cirrhosis

Hepatic encephalopathy (HE) is a serious neuropsychiatric complication of cirrhosis in alcoholic patients that is characterized clinically by personality changes, sleep abnormalities, and impaired motor coordination, as well as cognitive dysfunction progressing to stupor and coma. Procedures used for diagnosis and grading of HE include neurologic assessment, electroencephalography, psychometric testing, and use of the critical flicker frequency test. Neuropathologically, HE in cirrhosis is principally a disorder of neuroglia characterized by Alzheimer type II astrocytosis and activation of microglia. However, thalamic and cerebellar neuronal pathologies have been noted as well as lesions to globus pallidus and substantia nigra, leading to a condition known as "parkinsonism in cirrhosis." Multiple mechanisms have been proposed to account for the pathogenesis of HE in cirrhosis, including the neurotoxic actions of ammonia and manganese (normally removed via the hepatobiliary route), impaired brain energy metabolism, central proinflammatory mechanisms, and alterations of both excitatory and inhibitory neurotransmission. Treatment of HE in cirrhosis continues to rely on ammonia-lowering strategies such as lactulose, antibiotics, probiotics and l-ornithine l-aspartate with nutritional management consisting of adequate (but not excessive) dietary protein and vitamin B1 supplements. l-DOPA may improve parkinsonian symptoms. Liver transplantation leads to recovery of central nervous system function in the majority of cases.

Update on management of patients with overt hepatic encephalopathy

Hepatic encephalopathy (HE) is a multifactorial neuropsychiatric disease that affects patients with cirrhosis. We review the clinical impact, pathogenesis, evaluation, management, and prevention of overt HE in patients with cirrhosis. Articles published between January 1960 and November 2012 were acquired through a MEDLINE search of different combinations of the terms hepatic encephalopathy, pathophysiology, treatment, prophylaxis, prevention, prognosis, and recurrence. The Healthcare Cost and Utilization Project database was used to obtain prevalence and cost information related to hospitalizations of patients with HE. The literature describes significant morbidity and mortality of HE in patients with cirrhosis. Overt HE develops in 30% to 45% of patients with cirrhosis and is associated with a substantial pharmacoeconomic burden, particularly HE-related hospitalizations. The development of HE in patients with cirrhosis portends a worsened prognosis and is incorporated into the Child-Pugh classification of the severity of liver disease. In the hospitalized patient, the development of HE is associated with precipitating events (eg, gastrointestinal bleeding, dehydration, infection), and in some patients, its course is characterized by frequent and severe relapses. In addition, hospitalized patients with overt HE have a 3.9-fold increased mortality risk. Patient management employs nonabsorbable disaccharides, the nonsystemic antibiotic rifaximin, or both, to treat acute HE episodes and prevent HE relapse. In open-label trials, use of the nonabsorbable disaccharide lactulose reduced the risk of overt HE recurrence in patients compared with no-lactulose control groups for ≤ a median of 14 months. In a randomized, placebo-controlled trial, rifaximin 550 mg twice daily was more effective in maintaining HE remission compared with placebo and was associated with a reduction in HE-related hospitalizations. Recent advances in treatment and preventative therapies may reduce the personal, societal, and economic impact of this disorder.

Hepatic encephalopathy: an updated approach from pathogenesis to treatment

One of the most serious complications of chronic or fulminant liver failure is hepatic encephalopathy (HE), associated most commonly with cirrhosis. In the presence of chronic liver disease, HE is a sign of decompensation, while in fulminant liver failure its development represents a worrying sign and usually indicates that transplantation will be required. Despite the significance of HE in the course of liver disease, the progress in development of new therapeutic options has been unremarkable over the last 20 years. An up-to-date review regarding HE, including both research and review articles. HE is a serious and progressive, but potentially reversible, disorder with a wide spectrum of neuropsychiatric abnormalities and motor disturbances that ranges from mild alteration of cognitive and motor function to coma and death. Although a clear pathogenesis is yet to be determined, elevated ammonia in serum and the central nervous system is the mainstay for pathogenesis and treatment of HE. Management includes early diagnosis and prompt treatment of precipitating factors. Clinical trials and extensive clinical experience have established the efficacy of diverse substances in HE treatment. Novel therapies with clinical promise include: L-ornithine L-aspartate, sodium benzoate, phenylacetate, AST-120, and the molecular adsorbent recirculating system. Eventually, liver transplantation is often the most successful long-term therapy for HE.

New assessment of hepatic encephalopathy

Hepatic encephalopathy (HE) is a common complication of cirrhosis that requires careful appraisal of the clinical manifestations, evaluation of the underlying neurological disorders, and assessment of liver function and the portal-systemic circulation. This article reviews recent developments in the assessment of HE and discusses the controversy regarding the use of a categorical or a continuous approach in measuring the severity of this condition. New scales facilitate effective monitoring and assessment of episodic HE. Neuropsychological test batteries and neurophysiological tests are of value for evaluating cognitive function in outpatients and can establish the diagnosis of minimal HE, and the severity of low-grade HE. These tools allow better evaluation of the origin of cognitive complaints and help in estimating the risk of accidents. It is now possible to complete the evaluation with measurement of the effects of cognitive impairment on daily living. In difficult cases, imaging of the brain and portal-systemic circulation with magnetic resonance imaging is especially helpful. Based on these studies, neurological signs and symptoms can be attributed to HE in patients with mild liver disease and in those with complex neurological manifestations. The new methods presented are also valuable for investigating the neurological manifestations occurring after liver transplantation.

Portale Hypertension

Während die Pathologie, die zur portalen Hypertension führt, im prähepatischen, hepatischen und posthepatischen venösen Gefäßbett liegen kann, machen die intrahepatischen Erkrankungen mit Abstand den Großteil aus. In unseren Breitengraden ist es die durch Alkoholabusus bedingte ethyltoxische Leberzirrhose, weltweit die durch Infektionen (HCV, HBV) bedingten Zirrhosen. Die chronische Hepatitis C mit ihren Komplikationen (Leberzellversagen, portale Hypertension und hepatozelluläres Karzinom) wird in den kommenden Jahren trotz moderner Therapieverfahren noch an Bedeutung gewinnen.

Performance of the hepatic encephalopathy scoring algorithm in a clinical trial of patients with cirrhosis and severe hepatic encephalopathy

OBJECTIVES

The grading of hepatic encephalopathy (HE) is based on a combination of indicators that reflect the state of consciousness, intellectual function, changes in behavior, and neuromuscular alterations seen in patients with liver failure.

METHODS

We modified the traditional West Haven criteria (WHC) to provide an objective assessment of the cognitive parameters to complement the subjective clinical ratings for the performance of extracorporeal albumin dialysis (ECAD) using a molecular adsorption recirculating system in patients with cirrhosis and severe (grade III / IV) encephalopathy. The HE Scoring Algorithm (HESA) combined clinical indicators with those derived from simple neuropsychological tests,the latter more often used in milder grades of HE (I / II). The performance of each indicator was compared across grades and sites.

RESULTS

Results of HESA were also compared with the Glasgow Coma Scale. A total of 597 evaluations were performed in patients randomized to ECAD plus standard medical therapy or the latter only. Most parameters exhibited significant separation between grades; the most effective indicators were lack of verbal, eye, and motor response (grade IV), somnolence and disorientation to place (grade III), and lethargy and disorientation to time (grade II). Two clinical and four neuropsychological indicators were useful to classify patients as grade I. The Glasgow Coma Scale differed among the four stages of the WHC, but the differences between grades I and II were small and not clinically useful.

CONCLUSION

HESA extends the traditional WHC for grading HE. In the absence of a "gold" standard, the most useful indicators noted in this trial should be further validated.

Natural endogenous ligands for benzodiazepine receptors in hepatic encephalopathy

Benzodiazepines of natural origin (NBZDs) have been found in human blood and brains as well as in medicinal plants and foods. In plasma and brain tissue there are i.e. diazepam and nordiazepam equal to commercial drugs but there are also other benzodiazepine-like compounds termed "endozepines", which act as agonists at the benzodiazepine receptors of central type (CBR). A synthetic pathway for the production of NBZDs has not yet been found, but it has been suggested that micro-organisms may synthesize molecules with benzodiazepine-like structures. Hence NBZDs could be of both endogenous and exogenous source and be considered as natural anxyolitic and sedative. Interestingly there are also natural compounds, such as the polypeptide Diazepam Binding Inhibitor (DBI) acting as an "inversive agonist" implicated in fair and panic disorders. It has been suggested that NBZDs may play a role in the pathogenesis of hepatic encephalopathy (HE). Multidirectional studies evaluated NBZDs levels (1) in the blood of normal subjects, of cirrhotic with or without HE and in commercial benzodiazepine consumers; (2) in the blood of cirrhotic treated or not with a non-absorbable antibiotic; (3) in several constituents of our diet. In conclusion, NBZDs increase sometime in cirrhotics with or without HE but they reach concentrations not higher than those found in commercial benzodiazepines consumers. Hence NBZDs must be considered as occasional precipitating factor of HE and benzodiazepine antagonists only symptomatic drugs. The finding that NBZDs may be in part synthesized by intestinal bacterial flora and in part constituent of our diet underlines the importance to feed cirrhotic patients with selected food.

Effects of L-acetylcarnitine on cirrhotic patients with hepatic coma: randomized double-blind, placebo-controlled trial

Multiple therapeutic modalities have been used to treat hepatic encephalopathy. L: -Acetylcarnitine (LAC) is a physiologically active substance that improves both the energetic and the neurotransmission profiles. LAC is able to cross the hematoencephalic barrier and reach the cerebral regions, where the acetylic group may be utilized. The aim of this work was to evaluate the efficacy of LAC in the treatment of hepatic coma in cirrhotic patients. Twenty-four suitably selected patients were enrolled in the study and, following randomization, received either LAC (n=13) or placebo (n=11). Statistically significant differences in neurological findings, as evaluated by the Glasgow Scale, as well as in ammonia serum levels and BUN were found following LAC treatment. In the placebo group we observed two cases of improved neurological findings as well as one case of improved EEG grading. In the other group we observed an improvement of neurological findings and of EEG grade in 10 and 8 subjects, respectively. Noteworthily, seven (54%) patients went from grade 4 down to grade 3, and one from grade 4 down to grade 1. The improvement in the neurological picture was evident at between 1 and 4 hr after the end of treatment, remaining until 24 hr after. No side effects were observed in our study series. Our study demonstrates that LAC administration improved neurological and biohumoral symptoms in selective cirrhotic patients with hepatic coma.

Increased levels of pregnenolone and its neuroactive metabolite allopregnanolone in autopsied brain tissue from cirrhotic patients who died in hepatic coma

It has been suggested that neurosteroids with agonist properties at the central GABA-A receptor are implicated in the pathogenesis of hepatic encephalopathy (HE) in chronic liver disease. In order to address this issue, gas chromatography/mass spectrometry was used to measure the neurosteroids pregnenolone, allopregnanolone, and tetrahydrodeoxycorticosterone (THDOC) in postmortem brain tissue from controls, cirrhotic patients who died without HE, a patient who died in uremic coma, and cirrhotic patients who died in hepatic coma. Exposure of rat cerebral cortical membranes to brain extracts from hepatic coma patients resulted in a 53% (p < 0.001) increase in binding of [3H]muscimol, a GABA-A receptor ligand. Subsequent GC/MS analysis showed that concentrations of the GABA-A receptor agonist neurosteroid allopregnanolone were significantly increased in brain tissue from hepatic coma patients compared to patients without HE or controls (p < 0.001). Brain allopregnanolone concentrations were significantly correlated with the magnitude of induction of [3H]muscimol binding (r2 = 0.82, p < 0.0001). Concentrations of allopregnanolone comparable to those observed in hepatic coma brains are pathophysiologically relevant. Concentrations of the neurosteroid precursor pregnenolone were also increased in brain tissue from hepatic coma patients, while those of a second neurosteroid THDOC were below the levels of detection in all groups. Brain concentrations of benzodiazepine receptor ligands estimated by radioreceptor assay were not significantly increased in cirrhotic patients with or without hepatic coma. These findings suggest that increased levels of allopregnanolone rather than "endogenous benzodiazepines" offer a cogent explanation for the phenomenon of "increased GABAergic tone" previously proposed in HE.

Endozepines in recurrent stupor

Stupor is a condition from which the subject can be aroused only by vigorous stimuli. Most patients with stupor have a diffuse organic cerebral dysfunction. Rarely stupor is recurrent and no specific causes can be found. Patients with idiopathic recurrent stupor were awakened by i.v. administration of an antagonist (flumazenil) of the benzodiazepine recognition site located in the GABA(A) receptor. Since no exogenous benzodiazepines were detected in plasma and cerebrospinal fluid by high performance liquid chromatography, an excess of endogenous benzodiazepine-like compounds (endozepines) was proposed as the cause of stupor. The existence of endozepines, their widespread distribution in the CNS and their involvement in hepatic encephalopathy are established. However, the origin of these compounds, how biosynthesis occurs and the mechanisms and causes through which they alter brain functions are poorly understood. The fact that a number of synthetic benzodiazepines are difficult to detect using conventional techniques and the discovery that some cases of recurrent stupor were caused by fraudulent administration of lorazepam question whether the concept of endozepine recurrent stupor can be sustained. This review summarizes the state of endozepine physiology and pharmacology and the clinical syndromes attributed to their involvement. A diagnostic work-up to define endozepine-induced recurrent stupor is suggested.

Role of endogenous benzodiazepine ligands and their GABA-A--associated receptors in hepatic encephalopathy

Benzodiazepine receptor ligands are suggested to play a role in the pathogenesis of hepatic encephalopathy (HE). Accumulation of these ligands in brain was suggested to explain in part the notion of"increased GABAergic tone," the rational for which arose initially from reports of a beneficial effect of the selective benzodiazepine antagonist flumazenil in HE patients. It was suggested on the basis of the effect of flumazenil in human HE that liver failure may result in alterations of the density and/or affinity of the benzodiazepine-associated GABA-A receptor site. Subsequent controlled-clinical trials showed that fumazenil had a transient beneficial effect in only a subpopulation of HE patients. In contrast to the antagonists, partial inverse agonists of the benzodiazepine receptor have unequivocal beneficial effects on behavioral and electro-physiological performance in all experimental models of HE studied so far. Benzodiazepine-associated GABA-A receptors have consistently been demonstrated to be unaltered in both human and experimental HE. Contrary to initial reports, the so-called "endogenous benzodiazepines" do not appear to be significantly related to the pathogenesis of HE. On the other hand, nonbenzodiazepine GABA-A receptor complex modulators, such as neuro-steroids, recently identified in brain in human and experimental HE, may provide a new mechanistic basis for this disorder and lead to novel treatments for human HE.

Increased brain concentrations of endogenous (non-benzodiazepine) GABA-A receptor ligands in human hepatic encephalopathy

It has been suggested that alterations of GABAergic neurotransmission are implicated in the pathophysiology of hepatic encephalopathy (HE). Increased concentrations of endogenous benzodiazepines with positive allosteric modulatory properties at the GABA-A receptor complex were proposed as a pathophysiological mechanism to explain increased GABAergic tone in HE. However, results of controlled trials with benzodiazepine receptor antagonists have yielded equivocal results and increases in benzodiazepine levels in body fluids of cirrhotic patients were suggested to be largely accounted for by previous pharmaceutical benzodiazepine intake. In the present study the issue of benzodiazepine receptor ligands in brains of cirrhotic patients, and their contribution to alterations of GABA-A receptor complex in HE are addressed. "Benzodiazepine-like" ligands were present in trace amounts in autopsied brain tissue from control subjects (0.2 +/- 0.2 ng/g tissue), and from cirrhotic patients not previously exposed to benzodiazepine medication (0.8 +/- 0.4 ng/g tissue). In contrast, these ligands accumulate in brain extracts from cirrhotic patients previously exposed to benzodiazepines by up to 200-fold (161.5 +/- 93.2 DE ng/g tissue). Brain extracts from cirrhotic patients increased the binding of the GABA-A receptor agonist [3H]muscimol. This increase was minimal with brain extracts from controls (6.8 +/- 2.8%), but was significant with brain extracts from cirrhotic patients without (29.4 +/- 2.7%), or with (55.1 +/- 7.6%) previous exposure to benzodiazepines. Addition of flumazenil, a selective benzodiazepine receptor antagonist did not significantly modify the increase of [3H]muscimol binding by brain extracts from patients without prior exposure to benzodiazepines and only partially inhibited the increase of [3H]muscimol binding in presence of brain extracts from cirrhotic patients previously exposed to benzodiazepines. These findings suggest the presence of nonbenzodiazepine substances (possibly neurosteroids) with positive allosteric modulatory properties at the GABA-A receptor complex in brain in hepatic encephalopathy.

Pathophysiology of hepatic encephalopathy: a new look at GABA from the molecular standpoint

Hepatic encephalopathy (HE) is a neuropsychiatric disorder associated with either acute or chronic liver failure. More than two decades ago, the role of altered GABAergic neurotransmission was proposed following evidence of "increased GABAergic tone" in HE. Increased GABAergic tone was based on several observations: (i) Similarity of visual evoked response potential patterns between rabbits with galactosamine-induced fulminant hepatic failure and animals treated with various allosteric agonists of the GABA receptor complex (GRC). (ii) Spontaneous activities of isolated Purkinje neurons from rabbits with galactosamine-induced fulminant hepatic failure are more depressed by GRC modulator compounds compared to normal animals. (iii) Flumazenil, a high selective benzodiazepine antagonist at the GRC, ameliorates behavioral symptoms and EEG activity in some HE patients. Pathophysiological mechanisms put forward to explain increased GABAergic tone in HE include (1) increase in brain GABA content due to increased brain GABA uptake through altered permeability of the blood brain barrier, (2) alteration of the integrity of constituents of the GRC, and (3) increase of endogenous GRC modulators such as benzodiazepines (and more recently neurosteroids) with potent agonist properties at the GRC. Studies performed subsequently excluded alterations of either GABA content or GRC integrity in favor of increased brain concentrations of endogenous agonists. While the role of endogenous benzodiazepines remains controversial, the presence of neurosteroids with GABA agonist properties affords a plausible explanation for increased GABAergic tone in HE.

Benzodiazepine receptor antagonists for hepatic encephalopathy

BACKGROUND

Hepatic encephalopathy may be associated with accumulation of substances that bind to a receptor-complex in the brain resulting in neural inhibition. Benzodiazepine receptor antagonists may have a beneficial effect on patients with hepatic encephalopathy.

OBJECTIVES

To evaluate the beneficial and harmful effects of benzodiazepine receptor antagonists for patients with hepatic encephalopathy.

SEARCH STRATEGY

Eligible trials were identified through The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Controlled Trials Register on The Cochrane Library, MEDLINE and EMBASE (last search: January 2004), reference lists of relevant articles, authors of trials, and pharmaceutical companies.

SELECTION CRITERIA

Randomised trials comparing any benzodiazepine receptor antagonist versus placebo or no intervention for hepatic encephalopathy.

DATA COLLECTION AND ANALYSIS

Two reviewers independently included trials and extracted data. Binary outcomes are reported as risk difference (RD) with 95% confidence intervals (CI) based on a random effects model. Statistical heterogeneity was explored by a chi-squared test with significance set at P < 0.1. The inconsistency across trials was assessed by I(2). Potential sources of heterogeneity were explored through subgroup analyses.

MAIN RESULTS

Thirteen randomised trials with 805 patients were included. Eight trials used a crossover design. All trials were double-blind and assessed flumazenil versus placebo. Data on all outcomes could not be extracted from all trials. The included patients had a favourable prognosis (361/390 [93%] survived in the flumazenil group versus 345/376 [92%] in the placebo group). Flumazenil had a significant beneficial effect on improvement of hepatic encephalopathy at the end of treatment (RD 0.28; 95% CI 0.20 to 0.37, eight trials). Flumazenil had no significant effect on recovery (RD 0.13; 95% CI -0.09 to 0.36, two trials) or mortality RD 0.01; 95% CI -0.05 to 0.07, 10 trials). Flumazenil may be associated with adverse events, but trial results were heterogeneous.

REVIEWERS' CONCLUSIONS

Flumazenil had a significant beneficial effect on short-term improvement of hepatic encephalopathy in patients with cirrhosis and a highly favourable prognosis. Flumazenil had no significant effect on recovery or survival. Considering the fluctuating nature of hepatic encephalopathy, future trials should use a parallel design and assess if treatment with flumazenil leads to a sustained improvement or increased recovery and survival. Until this has been demonstrated, flumazenil may be considered for patients with chronic liver disease and hepatic encephalopathy, but cannot be recommended for routine clinical use.

Management of hepatic encephalopathy

Hepatic encephalopathy (HE) is seen as a clinical manifestation of low grade chronic cerebral edema, which is accompanied by alterations in glioneural communication. Different factors such as ammonia, inflammatory cytokines, benzodiazepines and electrolyte imbalances may precipitate or aggravate glia edema, thereby explaining precipitation of HE episodes by a variety of unrelated factors. Recognition and rigorous treatment of these precipitating factors is the most important measure in HE therapy which may be augmented by dietary and medical approaches. Among these approaches, evidence for proven therapeutical efficacy in HE on the basis of placebo-controlled trials is existing only for transplantation, protein restriction, administration of vegetable proteins, ornithine-aspartate, oral branched-chain amino acid treatment as well as lactulose enemas. The efficacy of oral lactulose has not been demonstrated on the basis of placebo-controlled trials.

Flumazenil vs. placebo in hepatic encephalopathy in patients with cirrhosis: a meta-analysis

BACKGROUND

Randomized controlled trials testing flumazenil in hepatic encephalopathy have shown conflicting results.

AIM

To compare flumazenil and placebo in hepatic encephalopathy in patients with cirrhosis.

METHODS

An overview of randomized controlled trials comparing flumazenil and placebo in hepatic encephalopathy in patients with cirrhosis was performed. For each end-point, heterogeneity and treatment efficacy were assessed by Peto and Der Simonian methods. As most trials were crossover in nature, a sensitivity analysis was performed including the two treatment periods.

RESULTS

Six double-blind randomized controlled trials, including 641 patients (326 treated with flumazenil and 315 with placebo), were identified. The treatment duration ranged from 5 min to 3 days. Heterogeneity tests between control groups were not significant. The mean percentages of patients with clinical improvement (five trials) were 27% in treated groups and 3% in placebo groups. This difference was significant by both methods (Peto: odds ratio=6.15; 95% confidence interval, 4.0-9.5; P < 0.001; Der Simonian: mean rate difference, 29%; 95% confidence interval, 17-41; P < 0.001). The mean percentages of patients with electroencephalographic improvement were 19% in treated groups and 2% in placebo groups. This difference was significant only with the Peto method (odds ratio=5.8; 95% confidence interval, 3.4-9.7; P < 0.001). The sensitivity analysis showed similar results.

CONCLUSIONS

This meta-analysis shows that flumazenil induces clinical and electroencephalographic improvement of hepatic encephalopathy in patients with cirrhosis.

Hepatic Encephalopathy

1. Acute Encephalopathy in Cirrhosis A. GENERAL MEASURES. Tracheal intubation in patients with deep encephalopathy should be considered. A nasogastric tube is placed for patients in deep encephalopathy. Avoid sedatives whenever possible. Correction of the precipitating factor is the most important measure. B. SPECIFIC MEASURES i. Nutrition. In case of deep encephalopathy, oral intake is withheld for 24-48 h and i.v. glucose is provided until improvement. Enteral nutrition can be started if the patient appears unable to eat after this period. Protein intake begins at a dose of 0.5 g/kg/day, with progressive increase to 1-1.5 g/kg/day. ii. Lactulose is administered via enema or nasogastric tube in deep encephalopathy. The oral route is optimized by dosing every hour until stool evacuation appears. Lactulose can be replaced by oral neomycin. iii. Flumazenil may be used in selected cases of suspected benzodiazepine use. 2. Chronic Encephalopathy in Cirrhosis i. Avoidance and prevention of precipitating factors, including the institution of prophylactic measures. ii. Nutrition. Improve protein intake by feeding dairy products and vegetable-based diets. Oral branched-chain amino acids can be considered for individuals intolerant of all protein. iii. Lactulose. Dosing aims at two to three soft bowel movements per day. Antibiotics are reserved for patients who respond poorly to disaccharides or who do not exhibit diarrhea or acidification of the stool. Chronic antibiotic use (neomycin, metronidazole) requires careful renal, neurological, and/or otological monitoring. iv. Refer for liver transplantation in appropriate candidates. For problematic encephalopathy (nonresponsive to therapy), consider imaging of splanchnic vessels to identify large spontaneous portal-systemic shunts potentially amenable to radiological occlusion. In addition, consider the combination of lactulose and neomycin, addition of oral zinc, and invasive approaches, such as occlusion of TIPS or surgical shunts, if present. Minimal or Subclinical Encephalopathy Treatment can be instituted in selected cases. The most characteristic neuropsychological deficits in patients with cirrhosis are in motor and attentional skills (60). Although these may impact the ability to perform daily activities, many subjects can compensate for these defects. Recent studies suggest a small but significant impact of these abnormalities on patients' quality of life (61), including difficulties with sleep (62). In patients with significant deficits or complaints, a therapeutic program based on dietary manipulations and/or nonabsorbable disaccharides may be tried. Benzodiazepines should not be used for patients with sleep difficulties.

Hepatic encephalopathy

In the last decade, a significant amount of research has been devoted to the pathogenesis and treatment of hepatic encephalopathy (HE). Non-invasive neuroimaging techniques such as magnetic resonance imaging and spectroscopy have become important research tools. The search for a suitable animal model of HE associated with cirrhosis is still ongoing. Moreover, consensus terminology and diagnostic criteria for HE in humans are badly needed.

Benzodiazepine receptor antagonists for acute and chronic hepatic encephalopathy

BACKGROUND

The pathogenesis of hepatic encephalopathy is unknown. It has been suggested that liver failure leads to the accumulation of substances that bind to a receptor-complex in the brain resulting in neural inhibition which may progress to coma. Several trials have assessed benzodiazepine receptor antagonists for hepatic encephalopathy, but the results are conflicting.

OBJECTIVES

To evaluate the efficacy and safety of benzodiazepine receptor antagonists for patients with acute or chronic hepatic encephalopathy.

SEARCH STRATEGY

Eligible trials were identified through The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Controlled Trials Register, MEDLINE, EMBASE, reference lists of relevant articles, authors of trials, and the pharmaceutical company known to produce benzodiazepine receptor antagonists.

SELECTION CRITERIA

Randomised trials comparing any benzodiazepine receptor antagonist versus placebo or no intervention for hepatic encephalopathy were included, regardless of language or publication status.

DATA COLLECTION AND ANALYSIS

Trial inclusion and data extraction were made independently by two contributors. Depending on the presence or absence of significant heterogeneity (P<0.1) a random or fixed effect model was used. Potential causes for heterogeneity were explored by sensitivity analyses.

MAIN RESULTS

Twelve randomised trials with 765 patients were included. Eight trials used a crossover design. All trials were double-blind and assessed flumazenil versus placebo. Data on all outcomes could not be extracted from all trials. The included patients had a favourable prognosis (341/370 (92%) survived in the flumazenil group versus 325/356 (91%) in the placebo group). Flumazenil had no significant effect on full recovery (two trials), survival (nine trials), or on the occurrence of adverse events (five trials). However, flumazenil was associated with a significant effect on improvement of hepatic encephalopathy compared to placebo at the end of treatment (103/346 (30%) versus 23/332 (7 %), risk difference 0.23, 95% confidence interval 0.18 to 0.28, five trials).

REVIEWER'S CONCLUSIONS

Flumazenil had no significant effect on recovery or survival from hepatic encephalopathy. However, flumazenil had a significant effect on short-term improvement of hepatic encephalopathy in some patients with chronic liver disease and a highly favourable prognosis. Considering the fluctuating nature of hepatic encephalopathy, future trials should use a parallel design and assess if treatment with flumazenil leads to a sustained improvement or increased recovery and survival. Until this has been demonstrated, flumazenil may be considered for patients with chronic liver disease and hepatic encephalopathy, but cannot be recommended for routine clinical use.

Diagnosis and treatment of hepatic encephalopathy

Hepatic encephalopathy arises from the combination of hepatocellular dysfunction and portal-systemic shunting. Encephalopathy is more prominent in advanced stages of liver cirrhosis and signals the presence of fulminant hepatic failure in patients with acute liver injury. As important as the extent of shunting is the presence of large spontaneous collaterals. Ammonia continues to be a leading toxin influencing brain function. Endogenous benzodiazepines and cytokines may contribute to one of ammonia's key effects in the brain: astrocyte swelling. The diagnosis of hepatic encephalopathy is a diagnosis of exclusion; the search for a precipitating factor should be started immediately in all cases of encephalopathy. The treatment of hepatic encephalopathy has three aims: decrease the nitrogenous load from the gut, improve the extra-intestinal elimination of ammonia and counteract central abnormalities of neurotransmission. The mainstay of treatment is directed at the colon. Newer approaches targeting the brain, such as flumazenil, have become available.

Liver transplantation. Selection, listing criteria, and preoperative management

Although only the expansion of the donor pool will have a major impact on the survival of patients with decompensated cirrhosis awaiting OLT, anticipation of complications such as SBP may improve the likelihood of a patient surviving until OLT, and may ameliorate some of the major causes of morbidity of cirrhosis, such as osteoporosis. Close communication between the treating physicians and the transplant center is crucial to ensure that the patients' UNOS status can be appropriately adjusted if additional complications of cirrhosis, such as intractable ascites, have occurred.

Complications of cirrhosis III. Hepatic encephalopathy

Hepatic encephalopathy (HE) is a major neuropsychiatric complication of cirrhosis. HE develops slowly in cirrhotic patients, starting with altered sleep patterns and eventually progressing through asterixis to stupor and coma. Precipitating factors are common and include an oral protein load, gastrointestinal bleeding and the use of sedatives. HE is common following transjugular intrahepatic portosystemic stent shunts (TIPS). Neuropathologically, HE in cirrhotic patients is characterized by astrocytic (rather than neuronal) changes known as Alzheimer type II astrocytosis and in altered expression of key astrocytic proteins. Magnetic resonance imaging in cirrhotic patients reveals bilateral signal hyperintensities particularly in globus pallidus on T1-weighted imaging, a phenomenon which may result from manganese deposition. Proton (1H) magnetic resonance spectroscopy shows increases in the glutamine resonance in brain, a finding which confirms previous biochemical studies and results no doubt from increased brain ammonia removal (glutamine synthesis). Additional evidence for increased brain ammonia uptake and removal in cirrhotic patients is provided by studies using positron emission tomography and 13NH3. Recent molecular biological studies demonstrate increased expression of genes coding for neurotransmitter-related proteins in chronic liver failure. Such genes include monoamine oxidase (MAO-A isoform), the peripheral-type benzodiazepine receptor and nitric oxide synthase (nNOS isoform). Activation of these systems has the potential to lead to alterations of monoamine and amino acid neurotransmitter function as well as modified cerebral perfusion in chronic liver failure. Prevention and treatment of HE in cirrhotic patients continues to rely on ammonia-lowering strategies which include assessment of dietary protein intake and the use of lactulose, neomycin, sodium benzoate and L-ornithine-aspartate. The benzodiazepine receptor antagonist flumazenil may be effective in certain cases. A more widespread use of central nervous system-acting drugs awaits a more complete understanding of the precise neurotransmitter systems involved in the pathogenesis of HE in chronic liver failure.

Plasma and CSF benzodiazepine receptor ligand concentrations in cirrhotic patients with hepatic encephalopathy: relationship to severity of encephalopathy and to pharmaceutical benzodiazepine intake

Increased plasma and CSF concentrations of substances which bind to brain benzodiazepine receptors have previously been reported in cirrhotic patients with hepatic encephalopathy (HE). However, their relationship to previous intake of pharmaceutical benzodiazepines has not been clearly established. In the present study, plasma levels of benzodiazepine receptor ligands (BZRLs) were measured using a sensitive radioreceptor assay in 12 control subjects with no evidence of hepatic, neurological or psychiatric illness, 11 cirrhotic patients without HE, 24 cirrhotic patients with moderate (grade I-II) HE and in 45 cirrhotic patients with severe (grade II-IV) HE. In addition, CSF concentrations of BZRLs were measured in 8 cirrhotic patients with HE and an equal number of age-matched controls. Recent intake (within 10 days) of pharmaceutical benzodiazepines was assessed by detailed review of medical files, and interviews with the patient, at least one family member as well as the pharmacist. Significantly increased plasma concentrations of BZRLs were observed in cirrhotic patients with severe encephalopathy (p < 0.02) compared to controls and to cirrhotic patients without (or with mild) neurological impairment. Increased plasma BZRLs could be accounted for by prior exposure to benzodiazepine medication in all cases. CSF concentrations of BZRLs in cirrhotic patients were not significantly different from control values. These findings do not support a role for "endogenous" benzodiazepines in the pathogenesis of HE in chronic liver disease but suggest that pharmaceutic benzodiazepines administered to cirrhotic patients as sedatives or as part of endoscopic work-up could have contributed to the neurological impairment in some patients.

Improvement of chronic hepatic encephalopathy in dogs by the benzodiazepine-receptor partial inverse agonist sarmazenil, but not by the antagonist flumazenil

Therapeutic modulation of the increased GABAergic tone in chronic hepatic encephalopathy (HE) by the benzodiazepine receptor (BR) antagonist flumazenil (F) has led to conflicting results in humans and animal models for HE. The BR inverse agonist sarmazenil (S) has only been used in animal models of acute HE. Therefore we investigated the effects of intravenous injection of F and S in dogs with chronic HE 8 to 12 weeks after placement of a portocaval shunt and 40% hepatectomy (n=7), compared to sham-operated pair-fed controls (n=7). The HE dogs had hyperammonemia (298 +/- 48 microM v 33 +/- 3 before surgery (mean +/- SEM)) and signs of HE at the start of the experiments (0.9 +/- 0.1 (scale 0-4)). Three (S3) and 8 (S8) mg/kg of S resulted in a significant improvement of encephalopathy (grade 0.9 +/- 0.2 immediately before v 0.5 +/- 0.1 after injection (S3) and 0.7 +/- 0.1 v 0.3 +/- 0.1 (S8)) and increase in mean dominant frequency of the EEG (MDF; 9.1 +/- 0.7 Hz v 11.1 +/- 0.3 (S3) and 8.9 +/- 0.5 v 11.0 +/- 0.3 (S8)) in HE dogs, whereas 15 mg/kg of S, 3 and 8 mg/kg of F, and the vehicle had no significant effects. The efficacy of S in these dogs is consistent with an increased GABAergic tone in the pathogenesis of chronic HE. The lack of effects of F makes a role for endogenous benzodiazepines herein unlikely.

Benzodiazepine-like substances and hepatic encephalopathy : implications for treatment

Hepatic encephalopathy is a neuropsychiatric syndrome that can complicate acute and chronic liver disease. Recent research has focused on the role benzodiazepine-like substances play in the pathogenesis of this disorder. It has been proposed that potentiation of the action of the neuroinhibitory transmitter γr-aminobutyric acid (GABA) through the binding of endogenous benzodiazepine agonists to the benzodiazepine receptor binding site accounts for the clinical and biochemical features of this condition.Increased levels of endogenous benzodiazepine-like substances have been noted in animal models of hepatic encephalopathy. In human studies, levels of these substances of up to 10 times those found in the body fluids of nonencephalopathic controls have been reported. The existence of such markedly elevated levels cannot be satisfactorily explained with reference to possible pharmaceutical or dietary origins.Further support for the role of benzodiazepines in the mediation of hepatic encephalopathy comes from the therapeutic effect reported after administration of the benzodiazepine receptor antagonist flumazenil. Improvements in the severity of hepatic encephalopathy have been documented in rats with fulminant hepatic failure given flumazenil, although results have been inconsistent according to the dose of flumazenil used and the procedure employed to induce the encephalopathy. Transient, but distinct, improvements in the grade of hepatic encephalopathy have also been documented in several human studies. In a placebo-controlled study involving patients with mild hepatic encephalopathy, a low dose of flumazenil (0.2 mg/kg) resulted in a significant improvement in reaction time.Research now needs to identify whether the beneficial effect of flumazenil is due to its antagonistic or inverse agonistic properties, and also to clarify the mechanisms by which the differential response to the drug in animal models of fulminant hepatic failure is mediated.

Cerebral abnormalities in patients with cirrhosis detected by proton magnetic resonance spectroscopy and magnetic resonance imaging

Hepatic encephalopathy is a common problem in cirrhosis. The pathogenesis of this complication of advanced liver disease still remains unclear. Magnetic resonance spectroscopy was used to assess prospectively cerebral metabolism in 51 patients with histologically proven cirrhosis (Child-Pugh classes A, B, and C, 18, 18, and 15, respectively) and 36 healthy volunteers. According to the results of psychometric tests, overt hepatic encephalopathy, subclinical encephalopathy, and no encephalopathy were found in 14, 21, and 16 patients, respectively. Myoinositol/creatine ratios in gray (.36 +/- .17) and white (.35 +/- .22) matter voxel were reduced significantly (P < .0001) in cirrhotic patients compared with healthy volunteers (gray matter, .51 +/- .11; white matter, .64 +/- .16). In addition, patients showed a significant reduction (P = .024) in white matter choline/creatine ratio (.77 +/- .27) compared with controls (.92 +/- .25), and glutamine/glutamate level was elevated in cirrhotic patients compared with controls (gray matter, P < .0001; white matter, P = .036). Changes in cerebral myoinositol and glutamine/glutamate levels correlated significantly with the severity of hepatic encephalopathy (P < .0001). However, these metabolic alterations were also detected in patients without hepatic encephalopathy (normal psychometric test results). N-acetyl aspartate/creatine ratios did not differ between patients and controls. Magnetic resonance imaging detected bright basal ganglia in 37 patients, which correlated significantly with portal-systemic shunting and elevation of glutamine/glutamate, but not with the degree of hepatic encephalopathy. In conclusion, magnetic resonance imaging and spectroscopy showed that alterations of cerebral metabolism are common in patients with cirrhosis, even without evidence of clinical or subclinical hepatic encephalopathy.