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Pharmacotherapy for Hepatic encephalopathy: view of Evidence-Based Medicine | OMICS International
ISSN: 2167-0889
Journal of Liver
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Pharmacotherapy for Hepatic encephalopathy: view of Evidence-Based Medicine

Ming-Hua Zheng1*, Dan-Qin Sun1, Qian Jiang2, Ke-Qing Shi1, Ai-Min Wu3 and Yong-Ping Chen1*
1Department of Infection and Liver Diseases, Liver Research Center, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou 325000, China
2Department of Pharmacy, the Second people’s Hospital of Sichuan Province, Sichuan provincial Cancer Hospital, Chengdu 610041, China
3Information Service Department, Library of Wenzhou Medical College, Wenzhou 325000, China
Corresponding Authors : Ming-Hua Zheng
Department of Infection and Liver Diseases, Liver Research Center
The First Affiliated Hospital of Wenzhou Medical College
No.2 Fuxue lane, Wenzhou, Zhejiang, China
Tel: (86) 577-88078232
Fax: (86) 577-88078262
E-mail: [email protected]
  Yong-Ping Chen
Department of Infection and Liver Diseases, Liver Research Center
The First Affiliated Hospital of Wenzhou Medical College
No.2 Fuxue lane, Wenzhou, Zhejiang, China
Tel: (86) 577-88078232
Fax: (86) 577-88078262
E-mail: [email protected]
Received October 20, 2011; Accepted December 15, 2011; Published December 18, 2011
Citation: Zheng MH, Sun DQ, Jiang Q, Shi KQ, Wu AM, et al. (2011) Pharmacotherapy for Hepatic encephalopathy: view of Evidence-Based Medicine. J Liver 1:102. doi:
Copyright: © 2011 Zheng MH, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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Abstract

Hepatic encephalopathy (HE) refers to a complex and reversible neuro-psychiatric syndrome that results from complications of acute or chronic hepatic failure, particularly alcoholic cirrhosis. It will lead to frequent life disruptions, poor quality of life and extensive use of health care resources. We conducted the review of several agents based on randomized controlled trials (RCTs) of high-quality Jadad scores (≥3) to provide effective information for clinical practice. Rifaximin appears at least to be as effective as conventional treatments, but not superior to them. L-Ornithine-L-aspartate appears to be a safe and effective treatment of chronic HE when compared with a placebo regime. Other treatments include non-absorbable disaccharides (NAD) and benzodiazepine receptor antagonists. In spite of the variability in the improvement of HE, NAD and non-absorbed antibiotics such as rifaximin offer a favorable benefit–risk ratio in the improvement of HE. Further RCTs with power calculation and a multi-centre approach with adequate population number are needed to resolve the heterogeneous results

Keywords
Hepatic encephalopathy; Randomized controlled trial; L-Ornithine-L-aspartate; Rifaximin
Introduction
Hepatic encephalopathy (HE) refers to a complex and reversible neuro-psychiatric syndrome that result from complications of acute or chronic hepatic failure, particularly alcoholic cirrhosis [1,2]. Clinical manifestations of HE can vary widely from minor signs of altered brain function, overt psychiatric, and/or neurological symptoms to deep coma, which will lead to frequent life disruptions, poor quality of life and extensive use of health care resources. It is also an independent risk factor for death [3].
The accumulation of unmetabolized toxins (primarily ammonia) in the brain, false neurotransmitters and neuro-inhibitory substances are believed to be the main mechanisms of HE. Precipitating factors include gastrointestinal bleeding, infections or systemic inflammatory response syndrome, renal and electrolyte disturbances, dehydration, use of psychoactive medications, constipation, excess dietary protein, and acute deterioration of liver function. Therefore, current management of HE focuses on exclusion of other causes of encephalopathy, identification of precipitating factors, resolution of the accumulation of neurotoxic byproducts of protein metabolism (measured by ammonia level) and correction of electrolyte balance [1-3].
The most commonly used therapies for treatment and prevention are non-absorbable disaccharides (NAD), in spite of limited studies evaluating the safety and efficacy, which calls for new therapeutics worldwide. Therefore, we conducted the review of several agents, e.g. rifaximin, L-Ornithine-L-aspartate (LOLA) based on randomized controlled trials (RCTs) of high-quality Jadad scores (≥3), which assessed the degree of randomization, blinding, subject withdrawals and dropouts, to provide effective information for clinical practice.
Rifaxinmin
Background: Rifaximin, a derivative of rifamycin, has a very low rate of systemic absorption (<0.4%) after oral administration, acts by inhibiting a spectrum of antibacterial ribonuclease acid synthesis. The drug was first introduced in Italy in 1987, and was used as first line therapy for hepatic encephalopathy in Europe, Asia, and Africa. In the United States, however, it was used for the treatment of non-dysenteric diarrhea, but not for HE [2]. During the past decade, numeric studies have identified that rifaximin was at least as safe and as effective as lactulose and other non-absorbable antibiotics, such as neomycin and paromomycin, for the treatment of HE [4-11].
Clinical efficacy of rifaximin: Clinical efficacy was defined as improvement of clinical syndrome, mental state and EEG and significant decrease of ammonia level. A total of five RCTs were registered in our study. The quality scores were listed in Table 1. All the included trials were of high quality. In these studies, two compared rifaximin with lactitol, three with lactulose, one with neomycin and the rest one with placebo (Table 1). The main features of these trials included are shown in Table 2.
In 1993, a randomized, double-blind, double-dummy, controlled trial was designed to compare rifaximin and lactulose for the treatment of patients with stage 1 porto-systemic encephalopathy (PSE) for 3 months. Mental status, ammonia level, asterixis and PSE severity were all improved. However, it concluded that clinical efficacy of rifaximin was not superior to lactulose. In an open-label prospective randomized trial conducted in Korea [9], the efficacy and safety of rifaximin was reported to be no better than lactulose (the HE index; rifaximin group (10.0 --> 4.2, p = 0.000); lactulose group (11.3 --> 5.0, p = 0.000). Mas et al. [8] conducted a randomized, double-blind, double-dummy controlled study of rifaximin 1,200 mg/day (n=50) and lactitol 60 g/ day (n=53) in patients with grade I–III and acute HE for 5-6 days. HE index mental status, asterixis, EEG and ammonia level were evaluated. The results had showed that PSE was decreased to some extent, due to a greater efficacy of blood ammino and EEG abnormalities. The total effectiveness was similar: 81.6% in the rifaximin group and 80.4% in the lactitol group, respectively. It suggested that rifaximin might be a good alternative for patients with acute HE of moderate to severe grade. Another high-quality controlled trial reported that rifaximin was not superior to lactitol [6]. Recently, Nathan M et al. [12] performed a RCT comparing rifaximin (n=140, 550mg, bid for 6 months) with placebo (n=159) in 299 patients. 87.9% of patients in the rifaximin group were in remission from recurrent HE resulting from chronic liver disease as compared with 54.1% of patients in the placebo group. The significant benefits for rifaximin were evident and also significantly reduced the risk of hospitalization from HE over a 6-month period.
There were several studies comparing rifaximin with neomycin and other antibiotics. Migllo et al.[13] designed a double-blind, randomized trial with 60 patients in grade 1-2 score at the dose of 1g three times daily.. This study indicated that rifaximin, was more effective than neomycin, although the difference was not significant. However, some oral antibiotics are not widespread due to adverse events profiles in the clinical studies.
Even though these studies reported conflicting results, our metaanalysis of rifaximin versus non-absorbale disaccharides in HE [14] concluded that there were no difference between the two regimes.
Adverse events: Rifaximin also has revealed adverse events (AEs), which were mainly gastrointestinal or systemic in nature. Paik et al. [9] reported that one patient treated with rifaximin complained of abdominal pain. It was easily managed by the physician. No serious events related to rifaximin were reported in this trial. Abdominal pain and diarrhea were also reported in the other two studies and no significant difference was observed when compared with NAD. The incidence of AEs published by Nathan was flatulence (14.3%), diarrhea (10.7%), nausea (14.3%), abdominal pain (8.6%), dyspepsia (6.4%), ascites (11.4%). Meanwhile, some serious events such as anemia, ascites, esophageal various, pneumonia were also reported in this study. However, all these studies estimated patients treated with rifaximin were more tolerant than those with NAD [8-9,15].
LOLA
Background: LOLA is a stable salt which is composed of the two amino acids L-Ornithine and L-Aspartate. The use of ornithineaspartate provides substrates for the urea cycle (ornithine) and for the synthesis of glutamine (aspartate, by the transamination to glutamate), while also diminishing ammonium levels. A number of preliminary uncontrolled trials with LOLA had been carried out since 1970s, but there was no clear assessment. However, over the past 10 years, several randomized controlled trials have been conducted [1,2,16].
Clinical efficacy of LOLA: Six high-quality trials were enrolled and characteristics were showed in Table 3. One involving 20 patients compared LOLA with lactulose and the other five compared with placebo (Table 4). LOLA is available both in oral or intravenous forms, and the recommended maximal intravenous infusion dose was 5g/h. Kircheis et al. [17] reported 126 patients with minimal or manifest lowgrade HE, who were randomized to LOLA group ( 20g/day infused for over 4 h) or placebo group for 7 days. According to the study, LOLA resulted in significant improvement of mental state grade and portalsystemic encephalopathy index (PSEI) compared with placebo (59% vs. 32%, respectively; p<0.001). Recently, an increasing number of studies were published. In 2006, a randomized lactulose-controlled study with 20 patients of chronic liver disease (3g/three times daily for 2 weeks ) indicated that there was no significant prominently difference [16]. In 2010, Schmid et al. [18] performed a double-blind, randomized, placebo-controlled trial which evaluated the effect of LOLA in cirrhotic. It reported LOLA might be superior to placebo and improved Posturography (equilibrium score (ES)) and PSE Syndrome Test (PSE) (ES: 5.3%; PSE: 1.9 vs ES: 3.9%; PSE: 1.3, respectively). A double-blind, randomized, placebo-controlled study was designed by Acharya S.K et al. [19] in order to assess the effectiveness of LOLA in acute liver failure. However, LOLA did not improve clinical symptom, reduce the mortality(mortality: 33.3% in placebo and 42.4% in LOLA) or decrease more ammonia level than placebo(P = 492). Based on these highquality studies, our meta-analysis showed that LOLA could markedly improve patients with mild to moderate HE [20].
Adverse events: Safety was also evaluated as important as efficacy and only a few adverse events such as abdominal pain, nausea and flatulence were frequently reported in these studies [16-18,20-22]. There were no serious adverse events related to LOLA and medications were well tolerated.
NADs
NADs, such as lactulose, were used as first-line therapies in 1966 and lactitol in 1980 which aimed to reduce intestinal derived production and absorption of ammonia and enhance its elimination [23].
Published studies reported the efficacy were finite for the improvement of HE. A systematic review of 22 RCTs identified that there was insufficient evidence to support or refute the use of NADs for HE and NADs were always served as the comparator in randomized trials on HE [24]. Recently, one trial had been reported that lactulose improved both cognitive function and health-related quality of life in patients with minimal HE [25]. However, no further studies were published.
Flumazenil
From a pathogenetic point of view, it is widely accepted that the cause of HE involved gamma-aminobutyric acid (GABA). GABA and benzodiazepine could make GABA-A receptor complex tick rapidly. Therefore, flumazenil a competitive benzodiazepine antagonist has high affinity with inhibition of GABA receptor binding sites [26-28].
A meta-analysis showed that flumazenil was more preponderant in clinical and ECG improvement of HE than placebo in patients with cirrhosis [29]. In addition, another meta-analysis of 13 randomized trials with 805 patients manifested that fulmazenil had an important effect on improvement of HE at the end of treatment (RD 0.28; 95% CI 0.20 to 0.37, eight trials). However, 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). It was associated with adverse events, but results were heterogeneous [26]. In summary, flumazenil may benefit patients with HE a lot. However, present studies do not recommend flumazenil routinely. Further studies on large patients are necessary to provide abundant evidence to the effectiveness of flumazenil.
Conclusion
Although there is variability in the improvement of HE, NADs and non-absorbed antibiotics, such as rifaximin, offer a favorable benefit– risk ratio in the improvement of HE. But, they should be recommended carefully in practice. We have entered an exciting phase in the research of HE and further RCTs with power calculation and a multi-centre approach with adequate population number are needed to resolve the heterogeneous results now.
Financial Support
This work was supported by grants from the Scientific Research Foundation of Wenzhou, Zhejiang Province, China (H20090014, Y20090269), Health Bureau of Zhejiang Province (2010KYB070), Research Foundation of Education Bureau of Zhejiang Province (Y201009942) and Project of New Century 551 Talent Nurturing in Wenzhou
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