Antibacterial activity of rifaximin reduces the levels of benzodiazepine-like compounds in patients with liver cirrhosis

Efficacy and tolerability of rifaximin in combination with lactulose in end-stage liver disease patients with MELD greater than 20: a single center experience

BACKGROUND

Rifaximin is a non-absorbable antibiotic which is approved for the treatment of hepatic encephalopathy (HE) in the United States. Our goal was to retrospectively assess this in patients with very advanced liver disease with our center data.

METHODS

Between 2003 and 2010, we examined a total of 286 consecutive patients from our center who were on a combination of rifaximin and lactulose, who had been evaluated or listed as eligible for a liver transplant. Patients who received less than 3 months of rifaximin and lactulose were excluded. Patients who had incomplete data; specifically, a lack of MELD score upon hospital admission were excluded from this analysis. The retrospective chart review was approved by the institutional review board.

RESULTS

We observed a total of 723 hospitalizations among the patients. Of the 723 hospitalizations, 218 were due to portosystemic encephalopathy (PSE), whereas 505 were due to other causes. We observed that patients with a MELD < 20 had an average of 2.5 hospitalizations per 6 month period, and that those with a MELD > 20 had an average of 1.6 hospitalizations per 6 month period for HE. At the same time, patients who had a MELD score < 20 had 3.29 hospitalizations for HE unrelated causes and those whose MELD was >20 had 3.73 hospitalizations for causes not related to HE. In this cohort 65% of all hospitalizations from HE were in patients whose MELD was < 20, and 35% of all hospitalizations were for patients with a MELD > 20.

CONCLUSION

In our experience, HE related hospitalizations were lower in patients whose MELD > 20 who were on a combination of rifaximin and lactulose compared to patients with MELD < 20. In contrast, patients whose MELD > 20 had greater hospitalizations for non HE events which may be an expected result owing to the overall increased severity of their liver disease. The limitation of this study is its retrospective nature and single center experience. In conclusion, administration of rifaximin appears to significantly reduce hospitalizations from HE in patients with MELD > 20 and therefore is advocated in maintenance of remission of HE in patients with very advanced liver disease.

Clinical effects of rifaximin in patientswith hepatic encephalopathy intolerant or nonresponsive to previous lactulose treatment: An open-label, pilot study

BACKGROUND

Hepatic encephalopathy (HE) is a metabolic-neurophysiologicsyndrome that occurs in patients with advanced hepatic disease. One of the main pathogenic mechanisms is represented by circulating toxins produced by the intestinal metabolism of nitrogenous compounds. The therapeutic approach to HE is mainly based on drugs that eliminate ammonia-producing bacteria.

OBJECTIVES

The aim of this study was to evaluate the effects of the nonabsorbable antibiotic rifaximin in patients with HE who were intolerant or nonresponsive to treatment with an oral, nonabsorbable disaccharide (lactulose).

METHODS

This uncontrolled, open-label, pilot study was conducted at the University of Bologna, Bologna, Italy. Patients aged ≥ 18 years with histologically proven liver cirrhosis and HE were studied. All patients were intolerant or nonresponsive to previous treatment with lactulose. Rifaximin tablets were administered to patients at a dosage of 400 mg TID for 10 days. The portal systemic encephalopathy (PSE) index was evaluated at enrollment and at the end of the treatment period. Tolerability was assessed using hematology, biochemistry, and urinalysis and by recording adverse effects (AEs).

RESULTS

Twenty-six patients (18 men, 8 women; mean [SD] age, 55.8 [8.0] years) were enrolled (intolerants, n = 17; nonresponders, n = 9). All patients completed the study. Significant improvement was shown in most of the 5 components of the PSE index after rifaximin administration in both intolerants and nonresponders. At the end of the 10-day treatment period, the PSE index was significantly reduced in both intolerants and nonresponders. Rifaximin was well tolerated; no clinically relevant AEs were observed during the treatment period.

CONCLUSIONS

This pilot study of patients with liver cirrhosis and HE who were intolerant or nonresponsive to previous treatment with an oral, nonabsorbable disaccharide suggests that treatment with rifaximin may be considered as an adjuvant or an alternative treatment in reducing HE.

Rifaximin

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Hepatic encephalopathy: pathophysiology and emerging therapies

Hepatic encephalopathy is characterized by neuropsychiatric abnormalities in patients with liver failure. Severe hepatic encephalopathy is an indication for liver transplantation as it portends poor outcome. Treatment of hepatic encephalopathy involves correction of precipitating factors such as sepsis, gastrointestinal bleeding, medications, and electrolyte imbalance. Effective therapies include lactulose and antibiotics such as neomycin, metronidazole, and rifaximin.

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.

Rifaximin for the treatment of hepatic encephalopathy

OBJECTIVE

To review the effectiveness and safety of rifaximin for the treatment of hepatic encephalopathy.

METHODS

A literature search was conducted of MEDLINE (1966-September 2007), the Cochrane Database of Systematic Reviews (1995-2007), and the Cochrane Hepato-Biliary Group Reviews (2003-2007). English-language articles identified from the data sources were evaluated. All available studies were reviewed, including placebo-controlled, treatment comparison, and open label.

RESULTS

Rifaximin was effective in improving behavioral, laboratory, mental status, and intellectual abnormalities associated with hepatic encephalopathy. Some studies demonstrated superior and more rapid improvement in signs or symptoms of encephalopathy during treatment with rifaximin compared with nonabsorbable disaccharides (lactulose, lactitol). Patients treated with rifaximin also required less hospitalization, had shorter duration of hospitalization, and lower hospital charges compared with lactulose-treated patients. Adverse effects of rifaximin were mostly minor gastrointestinal complaints; however, rifaximin was better tolerated than other pharmacologic treatments.

CONCLUSION

Rifaximin was at least equally effective as and in some studies superior to nonabsorbable disaccharides and antimicrobials in relieving signs or symptoms observed in patients with mild-to-moderately severe hepatic encephalopathy. Future clinical trials should focus on using standardized methods of evaluating mental status and limiting enrollment to patients with mild-to-moderate, episodic, persistent, or minimal hepatic encephalopathy. Well-designed studies are needed to fully delineate the efficacy of rifaximin and other pharmacologic treatments for patients with hepatic encephalopathy.

Pathogenesis of hepatic encephalopathy: the tumour necrosis factor-alpha theory

Hepatic encephalopathy (HE) is a major complication for acute and chronic liver failure. Despite several decades of intensive clinical and basic research, the pathogenesis of HE is still incompletely understood, and the precise mechanisms causing brain dysfunction in liver failure are still not fully established. Several theories concerning the pathogenesis of HE have been previously suggested, including the ammonia theory, which received the most attention. These theories are not mutually exclusive and the validity of none of them has been definitely proved experimentally. In this review article, an attractive theory concerning the pathogenesis of HE, the tumour necrosis factor-alpha (TNF) theory, is presented and comprehensively discussed after accumulation of sufficient data which indicate that the pro-inflammatory cytokine, TNF, is strongly involved in the pathogenesis of HE associated with both acute and chronic liver failure. This theory seems to be superior to all other previous theories in the pathogenesis of HE, and may induce development of other beneficial therapeutical modalities for HE directed towards inhibition of TNF production and/or action, and towards enhancement of its degradation.

Review article: bacterial flora and pathogenesis in hepatic encephalopathy

The aetiology of hepatic encephalopathy has not been conclusively established, but it is widely agreed that ammonia derived primarily from enteric bacterial flora plays a central role. Recent research on the pathogenesis of hepatic encephalopathy reinforces previous findings, supporting an integral role of bacteria-derived ammonia and reveals other potential mechanisms by which bacterial flora and pathogens may be pathophysiologically important. This review discusses this research and considers its implications for the therapeutic management of hepatic encephalopathy. Besides producing ammonia, the enteric flora generates other neurotoxic products, such as phenols and mercaptans, that may potentiate the effects of ammonia. Bacteria may also constitute a primary source of the benzodiazepine-like compounds implicated in neuropsychiatric symptoms in patients with liver disease. New evidence suggests that acute bacterial infections, long recognized as important precipitants of hepatic encephalopathy, may mediate clinical worsening through effects on systemic inflammatory responses. Considered together, these data suggest wide-ranging pathophysiological contributions of bacteria to hepatic encephalopathy and underline the potential for an integral role of antibiotics and other bactericidal agents in its management.

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.

Management of hepatic encephalopathy: role of rifaximin

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome, which develops in patients with acute or chronic liver failure. It is widely accepted to be due to impairment of hepatic clearance of toxic products from the gut such as ammonia. Accumulation of ammonia induces a glutamate neurotoxicity leading to an increased tone of the gamma-aminobutyric acid A (GABA-A) receptor system in the brain which results in HE. Factors either increasing the ammonia levels (protein load, constipation, sepsis, or gastrointestinal bleeding) or potentiating the functional activity of the GABAergic system [natural benzodiazepine-like compounds (NBZDs) or exogenous benzodiazepines] may act as precipitating factors of HE. NBZDs are present in trace amounts in the blood of normal subjects and have been found to be increased in the blood of patients with liver cirrhosis, with or without HE. These compounds may derive either from the diet since they have been found in plants, vegetables and animals or from gut bacteria. The observation that intestinal bacterial flora is involved in the production of both primary agent of HE (ammonia) and precipitating factors (NBZDs) suggests that the use of nonabsorbable antibiotics such as rifaximin may be useful in preventing episodes of HE in patients with liver cirrhosis.

Epithelial cell proliferation of the colonic mucosa in diverticular disease: a case-control study

BACKGROUND

A higher risk of both advanced adenoma and carcinoma occurs in the sigmoid colon of patients with diverticular disease, for which bacterial carcinogens have been claimed to play a role.

AIM

To assess epithelial cell proliferation in colonic mucosa of diverticular disease patients before and after rifaximin treatment.

METHODS

Twelve consecutive patients with a new endoscopic diagnosis of left-sided diverticular disease and 12 matched controls were enrolled. Epithelial cell proliferation in the sigmoid mucosa was assessed by using proliferating cell nuclear antigen. The proliferating cell nuclear antigen index of the whole crypt and of the upper third was separately evaluated before and after 10-day rifaximin (400 mg b.d.) therapy.

RESULTS

Proliferating cell nuclear antigen index in the upper third of the crypt was significantly higher in the diverticular patients (median: 25, range: 14-32) as compared with controls (median: 15, range: 5-20) (P = 0.038), and it was not reverted by rifaximin therapy. No difference of the proliferating cell nuclear antigen index of the whole crypt was detected between cases (median: 27, range: 23-44) and controls (median: 25, range: 18-42) (P = 0.6).

CONCLUSIONS

Our data showed an upward shifting of cellular proliferation in the sigmoid mucosa of patients with diverticular disease. Because of rifaximin failure in reversing this alteration, factors other than the bacterial load should probably be investigated.