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Hepatic Encephalopathy: Current and Emerging Treatment Modalities. Clin Gastroenterol Hepatol 2022; 20:S9-S19. [PMID: 35940731 DOI: 10.1016/j.cgh.2022.04.034] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/13/2022] [Accepted: 04/13/2022] [Indexed: 02/07/2023]
Abstract
Hepatic encephalopathy (HE) is a potentially reversible neurocognitive complication of cirrhosis. It has been reported in at least 30% of patients with cirrhosis and imposes a significant economic burden on caregivers and the healthcare system. Ammonia has been recognized as the culprit in HE development, and all the currently approved treatments mostly act on this toxin to help with HE resolution. After a brief overview of HE characteristics and pathophysiology, this review explores the current accepted treatments for this debilitating complication of cirrhosis. This is followed by an overview of the novel available therapies and a brief focus on future treatment modalities for HE.
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Safadi R, Rahimi RS, Thabut D, Bajaj JS, Ram Bhamidimarri K, Pyrsopoulos N, Potthoff A, Bukofzer S, Wang L, Jamil K, Devarakonda KR. Pharmacokinetics/pharmacodynamics of L-ornithine phenylacetate in overt hepatic encephalopathy and the effect of plasma ammonia concentration reduction on clinical outcomes. Clin Transl Sci 2022; 15:1449-1459. [PMID: 35238476 PMCID: PMC9199870 DOI: 10.1111/cts.13257] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 01/31/2022] [Accepted: 02/08/2022] [Indexed: 12/19/2022] Open
Abstract
Hepatic encephalopathy (HE) is a serious neurocognitive complication of liver dysfunction, often associated with elevated plasma ammonia. Ornithine phenylacetate (OP), a potent ammonia scavenger, is being evaluated for the treatment of acute/overt HE. The pharmacokinetics and pharmacodynamics of OP in patients with HE were characterized in this phase IIb study (NCT01966419). Adult patients hospitalized with an overt HE episode, cirrhosis, and plasma ammonia above the upper limit of normal (ULN) who failed to improve after 48 hours’ standard care were randomly assigned to continuous intravenous OP (10, 15, or 20 g/day, based on Child–Turcotte–Pugh score) or matching placebo for 5 days. Plasma levels of ornithine and phenylacetic acid (PAA) and plasma/urinary levels of phenylacetylglutamine (PAGN) (primary metabolite of PAA) were regularly assessed; plasma ammonia level was the primary pharmacodynamic variable. PAA demonstrated dose‐dependent pharmacokinetics; ornithine and PAGN levels increased with dose. PAGN urinary excretion represented ~50%–60% of administered PAA across all doses. Mean reduction in plasma ammonia with OP at 3 hours postinfusion was significantly greater versus placebo (p = 0.014); and time to achieve plasma ammonia less than or equal to the ULN was significantly reduced (p = 0.028). Achievement of clinical response based on HE stage was associated with a greater reduction in mean plasma ammonia level (p = 0.009). OP effects on plasma ammonia were consistent with its proposed mechanism of action as a primary ammonia scavenger, with a significant association between reduced plasma ammonia and improvement in HE stage. OP should be further evaluated as a promising treatment for hyperammonemia in patients with overt HE.
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Affiliation(s)
- Rifaat Safadi
- Director of The Liver Institute, Hadassah Medical Organization, Hadassah Hebrew University Medical Center, Jerusalem, Israel
| | - Robert S Rahimi
- Baylor Scott and White Hospital, Baylor University Medical Center, Dallas, Texas, USA
| | - Dominique Thabut
- Brain Liver Pitié-Salpêtrière (B-LIPS) Study Group, Paris Sorbonne Université, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Jasmohan S Bajaj
- Department of Medicine, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia, USA
| | | | - Nikolaos Pyrsopoulos
- Rutgers New Jersey Medical School and University Hospital, Newark, New Jersey, USA
| | - Amy Potthoff
- Ocera Therapeutics, Inc., Redwood City, California, USA
| | - Stan Bukofzer
- Ocera Therapeutics, Inc., Redwood City, California, USA
| | - Laurene Wang
- INDAPharma, LLC, Chapel Hill, North Carolina, USA
| | - Khurram Jamil
- Mallinckrodt Pharmaceuticals, Hampton, New Jersey, USA
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Rahimi RS, Safadi R, Thabut D, Bhamidimarri KR, Pyrsopoulos N, Potthoff A, Bukofzer S, Bajaj JS. Efficacy and Safety of Ornithine Phenylacetate for Treating Overt Hepatic Encephalopathy in a Randomized Trial. Clin Gastroenterol Hepatol 2021; 19:2626-2635.e7. [PMID: 33069881 DOI: 10.1016/j.cgh.2020.10.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 10/07/2020] [Accepted: 10/12/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Hepatic encephalopathy (HE) is associated with increased morbidity, mortality, and health care resource use. In this phase 2b study, we evaluated the efficacy and safety of ornithine phenylacetate (OP), an ammonia scavenger, in hospitalized patients with cirrhosis, increased levels of ammonia at screening, and acute or overt HE. METHODS We conducted a double-blind study of 231 patients with cirrhosis and HE at multiple sites in North America, Europe, Israel, and Australia from January 7, 2014, through December 29, 2016. Patients were assigned randomly to groups that received placebo or OP (10, 15, or 20 g/d, based on the severity of liver disease), plus each institution's standard of care (eg, lactulose to achieve 2-3 bowel movements with or without rifaximin, in accordance with guidelines). The primary end point was time to confirmed clinical response, defined as reduction to HE staging tool (HEST) stage 2 from baseline HEST stages 3/4 or improvement to HEST stages 0/1 from baseline stage 2, in the intent-to-treat population (all patients with increased levels of ammonia at screening, determined by a local laboratory). RESULTS Median times to clinical improvement, based on ammonia measurements at local laboratories, did not differ significantly between the groups given OP vs the placebo group (P = .129). Analyses of central laboratory-confirmed increases in levels of ammonia at baseline (n = 201) showed clinical improvement in HE at a median of 21 hours sooner in groups given OP vs placebo. The percentages of patients with any specific adverse event did not differ significantly between groups. Serious adverse events occurred in 25% of patients in the OP group and in 29% in the placebo group (P = .552). CONCLUSIONS In a randomized controlled trial of patients with cirrhosis and HE, we found no significant difference in time to clinical improvement between patients given OP vs placebo. However, OP appears to be safe and should undergo further testing for treatment of hyperammonemia in hospitalized patients receiving treatment for the underlying precipitant of acute or overt HE. ClinicalTrials.gov no: NCT01966419.
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Affiliation(s)
- Robert S Rahimi
- Transplant Hepatology, Baylor Scott and White Hospital, Baylor University Medical Center, Dallas, Texas.
| | - Rifaat Safadi
- The Liver Unit, Division of Medicine, Institute of Gastroenterology and Liver Diseases, Hadassah Medical Organization, Hadassah Hebrew University Medical Center, Jerusalem, Israel
| | - Dominique Thabut
- Hepatogastroenterology Department, Paris Sorbonne Université, Assistance Publique-Hôpitaux de Paris, Brain Liver Pitié-Salpêtrière Study Group, Paris, France
| | | | - Nikolaos Pyrsopoulos
- Division of Gastroenterology and Hepatology, Liver Transplantation, Rutgers New Jersey Medical School and University Hospital, Newark, New Jersey
| | - Amy Potthoff
- Clinical Operations, Ocera Therapeutics, Inc, Redwood City, California ∗∗Medical & Scientific Affairs, Ocera Therapeutics, Inc, Redwood City, California
| | - Stan Bukofzer
- Department of Medicine, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia
| | - Jasmohan S Bajaj
- Department of Medicine, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia
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Mohammadi H, Heidari R, Niknezhad SV, Jamshidzadeh A, Farjadian F. In vitro and in vivo Evaluation of Succinic Acid-Substituted Mesoporous Silica for Ammonia Adsorption: Potential Application in the Management of Hepatic Encephalopathy. Int J Nanomedicine 2020; 15:10085-10098. [PMID: 33363368 PMCID: PMC7754271 DOI: 10.2147/ijn.s271883] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Accepted: 11/20/2020] [Indexed: 12/21/2022] Open
Abstract
Purpose Hepatic encephalopathy (HE) is a critical situation in which liver failure affects brain function. HE could result in a state of coma and death. The liver is the main organ for ammonium ion (NH4 +) metabolism. Hence, acute and/or chronic liver failure could lead to hyperammonemia. NH4 + is the most suspected neurotoxic agent in HE. Thus, finding new therapeutic options to decrease plasma and brain NH4 + levels has a significant clinical value. Mesoporous silica (MS) particles have revolutionized many aspects of pharmaceutical sciences, including drug delivery systems. Moreover, recently, MS has been applied as agents for the detoxification of chemicals (eg, drugs and poisons). Methods First, MS particles containing amine groups (MS-NH2) were synthesized in co-condensation processes. Then, the structure was modified by succinic anhydride to have MS-SA. The MS-SA was characterized (FT-IR, XRD, X-ray photoelectron spectroscopy (XPS), DLS-Zeta FESEM-EDX, and HRTEM). Then, the potential of MS-NH2 and MS-SA particles in adsorption of NH4 + was investigated in vitro and in vivo. MS-NH2 and MS-SA were incubated with increasing concentrations (0.1-10 mM) of NH4 +, and the scavenging capacity of the investigated particles was evaluated. On the other hand, different doses (1 and 5 mg/kg per day) of nanoparticles were administered to a hyperammonemia animal model. Results It was figured out that both MS-NH2 and MS-SA significantly scavenged NH4 + in the in vitro model. However, the NH4 + scavenging capability of MS-SA was more significant. Administration of MS-NH2 and MS-SA also considerably decreased the level of ammonium in plasma and brain and improved cognitive and locomotor activity in hyperammonemic animals. The effects of MS-SA were more significant than MS-NH2 in the HE animal model. Conclusion Collectively, our data suggest that MS particles, especially succinic acid-functionalized MS, could act as special ancillary treatment in HE as a critical clinical complication.
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Affiliation(s)
- Hamidreza Mohammadi
- Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.,Department of Pharmacology and Toxicology, Faculty of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Reza Heidari
- Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Seyyed Vahid Niknezhad
- Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Akram Jamshidzadeh
- Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.,Department of Pharmacology and Toxicology, Faculty of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Fatemeh Farjadian
- Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
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Ryu AJ, Rahimi RS, Leise MD. The Current Hepatic Encephalopathy Pipeline. J Clin Exp Hepatol 2020; 10:377-385. [PMID: 32655239 PMCID: PMC7335727 DOI: 10.1016/j.jceh.2020.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 01/06/2020] [Indexed: 02/08/2023] Open
Abstract
Hepatic encephalopathy (HE) is a complication of acute or chronic liver failure; its mechanism is complex, involving multiple organ systems, and is still being elucidated. The standard of care, lactulose, has remained generally unchanged for decades. However, in recent years, better understanding of the pathophysiology has yielded new therapeutic targets for this reversible condition. These novel treatments act both on traditional pathways established in the ammonia hypothesis and through more recently discovered mechanisms. Here, we review contemporary investigational therapies for HE. We used narrative reviews and searched ClinicalTrials.gov database for the condition "hepatic encephalopathy" through August 29, 2019. Our review yielded six key areas of therapeutic focus: (1) antibiotics against urease-producing gut bacteria, (2) intravenous ammonia scavengers, (3) modified synthetic probiotics, (4) fecal microbiota transplant, (5) brain steroid-modulating agents, and 6) nonlactulose laxatives. Active trials are ongoing in each of these therapeutic areas.
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Key Words
- CHESS, clinical hepatic encephalopathy staging scale
- FMT, fecal microbiota transplant
- HE, hepatic encephalopathy
- HESA, hepatic encephalopathy scoring algorithm
- MAD, multiple-ascending dose
- MES, modified encephalopathy scale
- ORT, object recognition test
- PEG, polyethylene glycol-3350
- SAD, single-ascending dose
- SEV, saccadic eye velocity
- ammonia
- antibiotics
- fecal microbiota transplant
- hepatic encephalopathy
- lactulose
- therapy
- trials
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Affiliation(s)
- Alexander J. Ryu
- Department of Medicine, Mayo Clinic College of Medicine, Rochester, MN, United States
| | - Robert S. Rahimi
- Division of Hepatology, Baylor Scott & White Health, Dallas, TX, United States
| | - Michael D. Leise
- Division of Gastroenterology & Hepatology, Mayo Clinic College of Medicine, Rochester, MN, United States
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Abstract
This article reviews hepatic encephalopathy (HE) in companion animals. Clinical signs and categories of hepatic disease likely to cause HE are discussed. Ammonia has a key role in pathogenesis and current concepts in body ammonia metabolism are reviewed. Inflammation and manganese accumulation are also thought to be important in pathogenesis. Treatment of HE in acute and chronic cases is discussed along with the rationale for current treatment recommendations. Potential avenues for new treatments and human treatments, which may be transferable to companion animals, are reviewed.
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Affiliation(s)
- Adam G Gow
- Hospital for Small Animals, Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush, Edinburgh EH25 9RG, Scotland.
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