Pharmacotherapies that specifically target ammonia for the prevention and treatment of hepatic encephalopathy in adults with cirrhosis.

BACKGROUND: Hepatic encephalopathy is a common complication of cirrhosis, with high related morbidity and mortality. Its presence is associated with a wide spectrum of change ranging from clinically obvious neuropsychiatric features, known as 'overt' hepatic encephalopathy, to abnormalities manifest only on psychometric or electrophysiological testing, 'minimal' hepatic encephalopathy. The exact pathogenesis of the syndrome is unknown but ammonia plays a key role. Drugs that specifically target ammonia include sodium benzoate, glycerol phenylbutyrate, ornithine phenylacetate, AST-120 (spherical carbon adsorbent), and polyethylene glycol. OBJECTIVES: To evaluate the beneficial and harmful effects of pharmacotherapies that specifically target ammonia versus placebo, no intervention, or other active interventions, for the prevention and treatment of hepatic encephalopathy in people with cirrhosis. SEARCH METHODS: We searched the Cochrane Hepato-Biliary Controlled Trials Register, CENTRAL, MEDLINE, Embase, and three other databases to March 2019. We also searched online trials registries such as ClinicalTrials.gov, European Medicines Agency, WHO International Clinical Trial Registry Platform, and the Food and Drug Administration for ongoing or unpublished trials. In addition, we searched conference proceedings, checked bibliographies, and corresponded with investigators. SELECTION CRITERIA: We included randomised clinical trials comparing sodium benzoate, glycerol phenylbutyrate, ornithine phenylacetate, AST-120, and polyethylene glycol versus placebo or non-absorbable disaccharides, irrespective of blinding, language, or publication status. We included participants with minimal or overt hepatic encephalopathy or participants who were at risk of developing hepatic encephalopathy. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data from the included reports. The primary outcomes were mortality, hepatic encephalopathy, and serious adverse events. We undertook meta-analyses and presented results using risk ratios (RR) or mean differences (MD), both with 95% confidence intervals (CIs), and I2 statistic values as a marker of heterogeneity. We assessed bias control using the Cochrane Hepato-Biliary domains and the certainty of the evidence using GRADE. MAIN RESULTS: We identified 11 randomised clinical trials that fulfilled our inclusion criteria. Two trials evaluated the prevention of hepatic encephalopathy while nine evaluated the treatment of hepatic encephalopathy. The trials assessed sodium benzoate (three trials), glycerol phenylbutyrate (one trial), ornithine phenylacetate (two trials), AST-120 (two trials), and polyethylene glycol (three trials). Overall, 499 participants received these pharmacotherapies while 444 participants received a placebo preparation or a non-absorbable disaccharide. We classified eight of the 11 trials as at 'high risk of bias' and downgraded the certainty of the evidence to very low for all outcomes.Eleven trials, involving 943 participants, reported mortality data, although there were no events in five trials. Our analyses found no beneficial or harmful effects of sodium benzoate versus non-absorbable disaccharides (RR 1.26, 95% CI 0.49 to 3.28; 101 participants; 2 trials; I2 = 0%), glycerol phenylbutyrate versus placebo (RR 0.65, 95% CI 0.11 to 3.81; 178 participants; 1 trial), ornithine phenylacetate versus placebo (RR 0.73, 95% CI 0.35 to 1.51; 269 participants; 2 trials; I2 = 0%), AST-120 versus lactulose (RR 1.05, 95% CI 0.59 to 1.85; 41 participants; 1 trial), or polyethylene glycol versus lactulose (RR 0.50, 95% CI 0.09 to 2.64; 190 participants; 3 trials; I2 = 0%).Seven trials involving 521 participants reported data on hepatic encephalopathy. Our analyses showed a beneficial effect of glycerol phenylbutyrate versus placebo (RR 0.57, 95% CI 0.36 to 0.90; 178 participants; 1 trial; number needed to treat for an additional beneficial outcome (NNTB) 6), and of polyethylene glycol versus lactulose (RR 0.19, 95% CI 0.08 to 0.44; 190 participants; 3 trials; NNTB 4). We did not observe beneficial effects in the remaining three trials with extractable data: sodium benzoate versus non-absorbable disaccharides (RR 1.22, 95% CI 0.51 to 2.93; 74 participants; 1 trial); ornithine phenylacetate versus placebo (RR 2.71, 95% CI 0.12 to 62.70; 38 participants; 1 trial); or AST-120 versus lactulose (RR 1.05, 95% CI 0.59 to 1.85; 41 participants; 1 trial).Ten trials, involving 790 participants, reported a total of 130 serious adverse events. Our analyses found no evidence of beneficial or harmful effects of sodium benzoate versus non-absorbable disaccharides (RR 1.08, 95% CI 0.44 to 2.68; 101 participants; 2 trials), glycerol phenylbutyrate versus placebo (RR 1.63, 95% CI 0.85 to 3.13; 178 participants; 1 trial), ornithine phenylacetate versus placebo (RR 0.92, 95% CI 0.62 to 1.36; 264 participants; 2 trials; I2 = 0%), or polyethylene glycol versus lactulose (RR 0.57, 95% CI 0.18 to 1.82; 190 participants; 3 trials; I2 = 0%). Likewise, eight trials, involving 782 participants, reported a total of 374 non-serious adverse events and again our analyses found no beneficial or harmful effects of the pharmacotherapies under review when compared to placebo or to lactulose/lactitol.Nine trials, involving 733 participants, reported data on blood ammonia. We observed significant reductions in blood ammonia in placebo-controlled trials evaluating sodium benzoate (MD -32.00, 95% CI -46.85 to -17.15; 16 participants; 1 trial), glycerol phenylbutyrate (MD -12.00, 95% CI -23.37 to -0.63; 178 participants; 1 trial), ornithine phenylacetate (MD -27.10, 95% CI -48.55 to -5.65; 231 participants; 1 trial), and AST-120 (MD -22.00, 95% CI -26.75 to -17.25; 98 participants; 1 trial). However, there were no significant differences in blood ammonia concentrations in comparison with lactulose/lactitol with sodium benzoate (MD 9.00, 95% CI -1.10 to 19.11; 85 participants; 2 trials; I2 = 0%), AST-120 (MD 5.20, 95% CI -2.75 to 13.15; 35 participants; 1 trial), and polyethylene glycol (MD -29.28, 95% CI -95.96 to 37.39; 90 participants; 2 trials; I2 = 88%). FUNDING: Five trials received support from pharmaceutical companies while four did not; two did not provide this information. AUTHORS' CONCLUSIONS: There is insufficient evidence to determine the effects of these pharmacotherapies on the prevention and treatment of hepatic encephalopathy in adults with cirrhosis. They have the potential to reduce blood ammonia concentrations when compared to placebo, but their overall effects on clinical outcomes of interest and the potential harms associated with their use remain uncertain. Further evidence is needed to evaluate the potential beneficial and harmful effects of these pharmacotherapies in this clinical setting.

Carvedilol versus traditional, non-selective beta-blockers for adults with cirrhosis and gastroesophageal varices.

BACKGROUND: Non-selective beta-blockers are recommended for the prevention of bleeding in people with cirrhosis, portal hypertension and gastroesophageal varices. Carvedilol is a non-selective beta-blocker with additional intrinsic alpha1-blocking effects, which may be superior to traditional, non-selective beta-blockers in reducing portal pressure and, therefore, in reducing the risk of upper gastrointestinal bleeding. OBJECTIVES: To assess the beneficial and harmful effects of carvedilol compared with traditional, non-selective beta-blockers for adults with cirrhosis and gastroesophageal varices. SEARCH METHODS: We combined searches in the Cochrane Hepato-Biliary's Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, LILACS, and Science Citation Index with manual searches. The last search update was 08 May 2018. SELECTION CRITERIA: We included randomised clinical trials comparing carvedilol versus traditional, non-selective beta-blockers, irrespective of publication status, blinding, or language. We included trials evaluating both primary and secondary prevention of upper gastrointestinal bleeding in adults with cirrhosis and verified gastroesophageal varices. DATA COLLECTION AND ANALYSIS: Three review authors (AZ, RJ and LH), independently extracted data. The primary outcome measures were mortality, upper gastrointestinal bleeding and serious adverse events. We undertook meta-analyses and presented results using risk ratios (RR) or mean differences (MD), both with 95% confidence intervals (CIs), and I2 values as a marker of heterogeneity. We assessed bias control using the Cochrane Hepato-Biliary domains and the quality of the evidence with GRADE. MAIN RESULTS: Eleven trials fulfilled our inclusion criteria. One trial did not report clinical outcomes. We included the remaining 10 randomised clinical trials, involving 810 participants with cirrhosis and oesophageal varices, in our analyses. The intervention comparisons were carvedilol versus propranolol (nine trials), or nadolol (one trial). Six trials were of short duration (mean 6 (range 1 to 12) weeks), while four were of longer duration (13.5 (6 to 30) months). Three trials evaluated primary prevention; three evaluated secondary prevention; while four evaluated both primary and secondary prevention. We classified all trials as at 'high risk of bias'. We gathered mortality data from seven trials involving 507 participants; no events occurred in four of these. Sixteen of 254 participants receiving carvedilol and 19 of 253 participants receiving propranolol or nadolol died (RR 0.86, 95% CI 0.48 to 1.53; I2 = 0%, low-quality evidence). There appeared to be no differences between carvedilol versus traditional, non-selective beta-blockers and the risks of upper gastrointestinal bleeding (RR 0.77, 95% CI 0.43 to 1.37; 810 participants; 10 trials; I2 = 45%, very low-quality evidence) and serious adverse events (RR 0.97, 95% CI 0.67 to 1.42; 810 participants; 10 trials; I2 = 14%, low-quality evidence). Significantly more deaths, episodes of upper gastrointestinal bleeding and serious adverse events occurred in the long-term trials but there was not enough information to determine whether there were differences between carvedilol and traditional, non-selective beta-blockers, by trial duration. There was also insufficient information to detect differences in the effects of these interventions in trials evaluating primary or secondary prevention. There appeared to be no differences in the risk of non-serious adverse events between carvedilol versus its comparators (RR 0.55, 95% CI 0.23 to 1.29; 596 participants; 6 trials; I2 = 88%; very low-quality evidence). Use of carvedilol was associated with a greater reduction in hepatic venous pressure gradient than traditional, non-selective beta-blockers both in absolute (MD -1.75 mmHg, 95% CI -2.60 to -0.89; 368 participants; 6 trials; I2 = 0%; low-quality evidence) and percentage terms (MD -8.02%, 95% CI -11.49% to -4.55%; 368 participants; 6 trials; I2 = 0%; low-quality evidence). However, we did not observe a concomitant reduction in the number of participants who failed to achieve a sufficient haemodynamic response (RR 0.76, 95% CI 0.57 to 1.02; 368 participants; 6 trials; I2 = 42%; very low-quality evidence) or in clinical outcomes. AUTHORS' CONCLUSIONS: We found no clear beneficial or harmful effects of carvedilol versus traditional, non-selective beta-blockers on mortality, upper gastrointestinal bleeding, serious or non-serious adverse events despite the fact that carvedilol was more effective at reducing the hepatic venous pressure gradient. However, the evidence was of low or very low quality, and hence the findings are uncertain. Additional evidence is required from adequately powered, long-term, double-blind, randomised clinical trials, which evaluate both clinical and haemodynamic outcomes.