Effects of L-carnitine in patients with hepatic encephalopathy

L-Carnitine in the Treatment of Psychiatric and Neurological Manifestations: A Systematic Review

OBJECTIVE

L-carnitine (LC), a vital nutritional supplement, plays a crucial role in myocardial health and exhibits significant cardioprotective effects. LC, being the principal constituent of clinical-grade supplements, finds extensive application in the recovery and treatment of diverse cardiovascular and cerebrovascular disorders. However, controversies persist regarding the utilization of LC in nervous system diseases, with varying effects observed across numerous mental and neurological disorders. This article primarily aims to gather and analyze database information to comprehensively summarize the therapeutic potential of LC in patients suffering from nervous system diseases while providing valuable references for further research.

METHODS

A comprehensive search was conducted in PubMed, Web Of Science, Embase, Ovid Medline, Cochrane Library and Clinicaltrials.gov databases. The literature pertaining to the impact of LC supplementation on neurological or psychiatric disorders in patients was reviewed up until November 2023. No language or temporal restrictions were imposed on the search.

RESULTS

A total of 1479 articles were retrieved, and after the removal of duplicates through both automated and manual exclusion processes, 962 articles remained. Subsequently, a meticulous re-screening led to the identification of 60 relevant articles. Among these, there were 12 publications focusing on hepatic encephalopathy (HE), while neurodegenerative diseases (NDs) and peripheral nervous system diseases (PNSDs) were represented by 9 and 6 articles, respectively. Additionally, stroke was addressed in five publications, whereas Raynaud's syndrome (RS) and cognitive disorder (CD) each had three dedicated studies. Furthermore, migraine, depression, and amyotrophic lateral sclerosis (ALS) each accounted for two publications. Lastly, one article was found for other symptoms under investigation.

CONCLUSION

In summary, LC has demonstrated favorable therapeutic effects in the management of HE, Alzheimer's disease (AD), carpal tunnel syndrome (CTS), CD, migraine, neurofibromatosis (NF), PNSDs, RS, and stroke. However, its efficacy appears to be relatively limited in conditions such as ALS, ataxia, attention deficit hyperactivity disorder (ADHD), depression, chronic fatigue syndrome (CFS), Down syndrome (DS), and sciatica.

Brown adipose tissue-derived metabolites and their role in regulating metabolism

The discovery and rejuvenation of metabolically active brown adipose tissue (BAT) in adult humans have offered a new approach to treat obesity and metabolic diseases. Beyond its accomplished role in adaptive thermogenesis, BAT secretes signaling molecules known as "batokines", which are instrumental in regulating whole-body metabolism via autocrine, paracrine, and endocrine action. In addition to the intrinsic BAT metabolite-oxidizing activity, the endocrine functions of these molecules may help to explain the association between BAT activity and a healthy systemic metabolic profile. Herein, we review the evidence that underscores the significance of BAT-derived metabolites, especially highlighting their role in controlling physiological and metabolic processes involving thermogenesis, substrate metabolism, and other essential biological processes. The conversation extends to their capacity to enhance energy expenditure and mitigate features of obesity and its related metabolic complications. Thus, metabolites derived from BAT may provide new avenues for the discovery of metabolic health-promoting drugs with far-reaching impacts. This review aims to dissect the complexities of the secretory role of BAT in modulating local and systemic metabolism in metabolic health and disease.

The role of genetic defects in carnitine-associated hepatic encephalopathy: a review of literature

Hepatic encephalopathy (HE) is a serious neurological disorder characterized by brain dysfunction due to liver failure which occurs as a result of chronic or acute liver disease. HE can manifest with various neurological or psychiatric symptoms ranging from excessive sleepiness and sleep disorders to coma. HE is a serious disorder that in acute conditions can even lead to the death of the patient due to cerebral edema. Carnitine acts as a vital component in facilitating the transport of long-chain fatty acids into the mitochondria, thereby enabling their oxidation for the generation of energy. Carnitine additionally assumes a crucial role in the functionality of the brain. Carnitine deficiency is associated with various types of inherited disorders related to low levels of carnitine. A strong correlation exists between the insufficiency of carnitine and the occurrence of HE. If a deficiency of carnitine is identified through clinical symptoms or laboratory results in patients with liver dysfunction, treatment with carnitine replacement therapy is recommended. Thus, the administration of acetyl-L-carnitine in patients with HE can improve their mental and psychological conditions. In the present study, we provide an overview of the molecular and cellular mechanisms underlying HE. Our aim in this review has been genetic investigation of HE and genetic mutations to the causes of this neurological condition, which include carnitine deficiency, hyperammonemia, and etc. Finally, we discuss the genetic mutations that lead to carnitine deficiency as well as hyperammonemia and are associated with this neurological disease, together with the future treatment of this disease based on carnitine therapy. More studies soon will help early diagnosis (before poor prognosis) based on clinical observations, genetic tests, prenatal diagnosis, and new treatment strategies. Hepatic encephalopathy, Carnitine, Ammonia, Genetic, Treatment.

Treatment of Hyperammonemia Syndrome in Lung Transplant Recipients

Hyperammonemia syndrome is a complication that has been reported to occur in 1-4% of lung transplant patients with mortality rates as high as 60-80%, making detection and management crucial components of post-transplant care. Patients are treated with a multimodal strategy that may include renal replacement therapy, bowel decontamination, supplementation of urea cycle intermediates, nitrogen scavengers, antibiotics against Mollicutes, protein restriction, and restriction of parenteral nutrition. In this review we provide a framework of pharmacologic mechanisms, medication doses, adverse effects, and available evidence for commonly used treatments to consider when initiating therapy. In the absence of evidence for individual strategies and conclusive knowledge of the causes of hyperammonemia syndrome, clinicians should continue to design multimodal regimens based on suspected etiologies, institutional drug availability, patient ability to tolerate enteral medications and nutrition, and availability of intravenous access.

A metabolomics approach to the validation of predictive metabolites and phenotypic expression in non-alcoholic fatty liver disease

AIMS

Nonalcoholic fatty liver disease (NAFLD) is becoming more common and severe. Individuals with NAFLD have an altered composition of gut- microbial metabolites. We used metabolomics profiling to identify microbial metabolites that could indicate gut-liver metabolic severity. Noninvasive biomarkers are required for NAFLD, especially for patients at high risk of disease progression.

MAIN METHODS

We compared the stool metabolomes, untargeted metabolomics, and clinical data of 80 patients. Patients with nonalcoholic fatty liver (NAFL: n = 16), nonalcoholic steatohepatitis (NASH: n = 26), and cirrhosis (n = 19) and healthy control individuals (HC: n = 19) were enrolled. The identified metabolites in NAFLD were evaluated by multivariate statistical analysis and metabolic pathotypic expression. Gas chromatography-mass spectrometry (GC-MS) and liquid chromatography coupled to time-of-flight-mass spectrometry (LC-TOF-MS) were used to analyze metabolites.

KEY FINDINGS

Untargeted metabolomics was used to identify and quantify 103 metabolites. Principal component analysis (PCA) was used to assess the metabolic discrimination of NAFL, NASH, and cirrhosis. Short-chain fatty acids (SCFA) levels were significantly lower in NAFLD patients, including those of acetate (p = 0.03), butyrate (p = 0.0008), and propionate. The stool cholic acid (p = 0.001) level was significantly increased in NAFLD patients. Palmitoylcarnitine and l-carnitine levels were significantly increased in NASH and cirrhosis patients. The phenotypic expression of these metabolites was linked to β-oxidation.

SIGNIFICANCE

We demonstrated a distinct metabolome profile in NAFLD patients with NAFL, NASH, and cirrhosis. We also discovered that the expression of certain metabolites and metabolic pathways was linked to NAFLD.

Add-on Therapeutic Effects of Rifaximin on Treatment-resistant Hepatic Encephalopathy

Objective Rifaximin is used to treat hepatic encephalopathy. However, whether or not rifaximin and lactulose combination therapy can enhance the treatment outcomes and reduce the hospitalization rate of patients with hepatic encephalopathy that are resistant to lactulose has yet to be determined. The present study investigated the hospitalization rate before and after rifaximin add-on therapy in patients resistant to lactulose. Methods A total of 36 patients who were resistant to lactulose with add-on rifaximin therapy were enrolled. Patients who were hospitalized and/or did not achieve normalization of ammonia levels under lactulose administration were defined as treatment-resistant. The primary outcome was the change in hospitalization rate due to hepatic encephalopathy at 24 weeks before and after rifaximin administration. Results Before rifaximin administration, 15 (41.6%) patients were hospitalized due to hepatic encephalopathy. After rifaximin administration, 8 (22.2%) patients were hospitalized due to hepatic encephalopathy. The hospitalization rates were significantly reduced after rifaximin administration (p=0.02). The median (interquartile range) ammonia levels upon rifaximin administration (baseline) and 8, 12, and 24 weeks after rifaximin administration were 124 (24-310) μg/dL, 78 (15-192) μg/dL, 67 (21-233) μg/dL, and 77 (28-200) μg/dL, respectively. Furthermore, the ammonia levels were significantly reduced by rifaximin add-on therapy (p=0.005, p=0.01, and p=0.01). Conclusion The addition of rifaximin to lactulose treatment in treatment-resistant patients decreases the hospitalization rate among patients with hepatic encephalopathy and may be used as an add-on treatment.

Residual Amino Acid Imbalance in Rats during Recovery from Acute Thioacetamide-Induced Hepatic Encephalopathy Indicates Incomplete Healing

The delayed consequences of the influence of hepatic encephalopathy (HE) on the metabolism of animals have not been studied enough. We have previously shown that the development of acute HE under the influence of the thioacetamide (TAA) toxin is accompanied by pathological changes in the liver, an imbalance in CoA and acetyl CoA, as well as a number of metabolites of the TCA cycle. This paper discusses the change in the balance of amino acids (AAs) and related metabolites, as well as the activity of glutamine transaminase (GTK) and ω-amidase enzymes in the vital organs of animals 6 days after a single exposure to TAA. The balance of the main AAs in blood plasma, liver, kidney, and brain samples of control (n = 3) and TAA-induced groups (n = 13) of rats that received the toxin at doses of 200, 400, and 600 mg/kg was considered. Despite the apparent physiological recovery of the rats at the time of sampling, a residual imbalance in AA and associated enzymes persisted. The data obtained give an idea of the metabolic trends in the body of rats after their physiological recovery from TAA exposure and may be useful for prognostic purposes when choosing the necessary therapeutic agents.

Tricarboxylic Acid Metabolite Imbalance in Rats with Acute Thioacetamide-Induced Hepatic Encephalopathy Indicates Incomplete Recovery

Exposure to the toxin thioacetamide (TAA) causes acute hepatic encephalopathy (HE), changes in the functioning of systemic organs, and an imbalance in a number of energy metabolites. The deferred effects after acute HE development are poorly understood. The study considers the balance of the tricarboxylic acid (TCA) cycle metabolites in the blood plasma, liver, kidneys, and brain tissues of rats in the post-rehabilitation period. The samples of the control (n = 3) and TAA-induced groups of rats (n = 13) were collected six days after the administration of a single intraperitoneal TAA injection at doses of 200, 400, and 600 mg/kg. Despite the complete physiological recovery of rats by this date, a residual imbalance of metabolites in all the vital organs was noted. The results obtained showed a trend of stabilizing processes in the main organs of the animals and permit the use of these data both for prognostic purposes and the choice of potential therapeutic agents.

Current status of primary liver cancer and decompensated cirrhosis in Japan: launch of a nationwide registry for advanced liver diseases (REAL)

BACKGROUND

We developed a nationwide database that stores data of patients with primary liver cancer (PLC) and decompensated cirrhosis (DC) on an admission basis.

METHODS

A database was constructed using the National Clinical Database, a nationwide registry platform for various diseases in Japan. Mutual data exchange was possible with the Nationwide Follow-up Survey of Primary Liver Cancer in Japan by the Liver Cancer Study Group of Japan. The stored data on the admission of patients with PLC, DC, or both, included treatment details as well as patient characteristics.

RESULTS

A total of 37,705 admissions (29,489 PLC, 10,077 DC, and 1862 for both) in 21,376 patients from 224 hospitals were analyzed. The proportions of patients with hepatitis B, hepatitis C, and non-viral etiology were 11.9%, 36.2%, and 42.6%, respectively, in PLC, and 7.5%, 23.8%, and 55.0%, respectively, in DC. The mean ages (± standard deviation) on admission with PLC and DC were 73 ± 10 and 68 ± 13 years, respectively. The Barcelona Clinic Liver Cancer (BCLC) stage for PLC was 0, A, B, C, and D in 22.0%, 17.1%, 29.6%, 15.1%, and 5.1%, respectively. Treatment modalities for PLC were resection, ablation, transarterial chemoembolization, and systemic therapy in 18.4%, 22.8%, 33.7%, and 11.4%, respectively. A vasopressin receptor V2 antagonist was used in 38.2% in addition to conventionally used loop diuretics and aldosterone antagonists for DC.

CONCLUSIONS

The distribution of treatment options for PLC on admission differed from that of the initial treatment. Newly introduced drugs are widely used in patients with DC.

Role of Carnitine in Non-alcoholic Fatty Liver Disease and Other Related Diseases: An Update

Carnitine is an amino acid-derived substance that coordinates a wide range of biological processes. Such functions include transport of long-chain fatty acids from the cytoplasm to the mitochondrial matrix, regulation of acetyl-CoA/CoA, control of inter-organellar acyl traffic, and protection against oxidative stress. Recent studies have found that carnitine plays an important role in several diseases, including non-alcoholic fatty liver disease (NAFLD). However, its effect is still controversial, and its mechanism is not clear. Herein, this review provides current knowledge on the biological functions of carnitine, the “multiple hit” impact of carnitine on the NAFLD progression, and the downstream mechanisms. Based on the “multiple hit” hypothesis, carnitine inhibits β-oxidation, improves mitochondrial dysfunction, and reduces insulin resistance to ameliorate NAFLD. L-carnitine may have therapeutic role in liver diseases including non-alcoholic steatohepatitis, cirrhosis, hepatocellular carcinoma, alcoholic fatty liver disease, and viral hepatitis. We also discuss the prospects of L-carnitine supplementation as a therapeutic strategy in NAFLD and related diseases, and the factors limiting its widespread use.

Brain Herniation and Intracranial Hypertension

This article introduces the basic concepts of intracranial physiology and pressure dynamics. It also includes discussion of signs and symptoms and examination and radiographic findings of patients with acute cerebral herniation as a result of increased as well as decreased intracranial pressure. Current best practices regarding medical and surgical treatments and approaches to management of intracranial hypertension as well as future directions are reviewed. Lastly, there is discussion of some of the implications of critical medical illness (sepsis, liver failure, and renal failure) and treatments thereof on causation or worsening of cerebral edema, intracranial hypertension, and cerebral herniation.

L-carnitine reduces hospital admissions in patients with hepatic encephalopathy

AIM

The aim of this study was to determine whether oral L-carnitine administration reduces the blood ammonia concentration and number of hospital admissions for hepatic encephalopathy in patients with advanced cirrhosis.

METHODS

Of 68 patients with hepatic encephalopathy treated with oral L-carnitine supplementation from April 2013 to March 2016, we enrolled 19 patients who had received full standard treatment. We analyzed blood ammonia concentration, number of hospital admissions, and prognosis to determine how effective L-carnitine was in achieving mid-term to long-term suppression of recurrent hepatic encephalopathy.

RESULTS

Median blood ammonia concentrations at the start, 1 week, 12 weeks, 24 weeks, and 48 weeks were 159, 79, 75, and 82 μg/dL, respectively. Blood ammonia concentrations 12 week, 24 weeks, and 48 weeks after L-carnitine administration were significantly lower than those at the start (P < 0.0001, respectively). During the 3 years prior to oral L-carnitine administration, the enrolled patients were hospitalized a total of 29 times for hepatic encephalopathy. However, during the 3 years following oral L-carnitine administration, they were admitted a total of six times for hepatic encephalopathy (P < 0.001). Median survival time was 40.9 months. Child-Pugh scores before and after oral L-carnitine administration differed significantly, whereas liver reserve function, nutritional status, and muscle index did not change significantly.

CONCLUSIONS

Oral L-carnitine administration is effective and free of adverse effects in patients with hyperammonemia and reduces the number of hospital admissions for hepatic encephalopathy.

The Efficacy of Levocarnitine Treatment in Relieving Fatigue in Patients with Cirrhosis but without Overt Hepatic Encephalopathy

Objective In the present study, we prospectively examined the efficacy of levocarnitine in relieving symptoms of fatigue in patients with cirrhosis but without overt hepatic encephalopathy. Methods Twenty-one cirrhotic patients who were able to undergo fatigue symptom evaluations at our institution were enrolled. A total of 12 cirrhotic patients underwent levocarnitine treatment (1,200-1,800 mg/day), while 9 did not undergo levocarnitine treatment. As primary endpoints, we investigated whether or not levocarnitine treatment exerted any beneficial effects by assessing the symptoms of fatigue [8-item Short-Form Health Survey (SF-8) and Fisk Fatigue Severity Score (FFSS)] at baseline and three months after treatment. Furthermore, as exploratory secondary endpoints, we investigated whether or not levocarnitine treatment exerted ameliorative effects on oxidative stress by assessing the serum thioredoxin (TRX) and urinary 8-hydroxydeoxyguanosine (8-OHdG) levels. Results The median age of the patients was 73 years old. Three men and 18 women were categorized by their Child-Pugh class (A and B in 14 and 7 patients, respectively). There were no significant differences in the clinical laboratory values between the two groups. The FFSS and SF-8 scores were significantly improved in the patients with cirrhosis who underwent levocarnitine treatment (p<0.01) but not in those who did not undergo levocarnitine treatment. Furthermore, three months after levocarnitine treatment, the serum carnitine concentrations were significantly increased, and the serum thioredoxin levels were decreased in the patients with cirrhosis who underwent levocarnitine treatment (p<0.05). Conclusion These results suggest that levocarnitine treatment may relieve symptoms of fatigue in cirrhotic patients by reducing oxidative stress.

Evaluation of the Long-term Administration of Rifaximin for More than Three Years in the Treatment of Repeated and Recurrent Overt Hepatic Encephalopathy

The patient was a 65-year-old man with alcoholic liver cirrhosis who had been admitted to hospital 5 times for repeated and recurrent overt hepatic encephalopathy (HE) despite numerous therapies, including disaccharide, branched-chain amino acid (BCAA) formula, L-carnitine and zinc. After the additional administration of rifaximin (1,200 mg/day orally), his consciousness level was well controlled for 3 years without any adverse effects. The long-term administration of rifaximin may be useful and safe for managing recurrent overt HE, although the maintenance dosage and duration of rifaximin and safety should be evaluated in patients with ameliorated HE.

Impaired brain function improved by L-carnitine in patients with cirrhosis: evaluation using near-infrared spectroscopy

To evaluate the effects of l-carnitine on impaired brain function in patients with liver cirrhosis. We conducted a retrospective cohort study that included sequential 80 liver cirrhosis patients with impaired brain function evaluated using near-infrared spectroscopy (NIRS). Among them, l-carnitine was administered to 48 patients. The NIRS data and blood ammonia level at baseline and after 8 weeks of treatment were compared between patients administered with l-carnitine (l-carnitine group) and those who were not (control group). The NIRS data at baseline were similar between the l-carnitine and control groups (0.04 ± 0.04 vs. 0.04 ± 0.05 mMmm, p = n.s), whereas those in the l-carnitine group (n = 48) were significantly better than that of the control group at 8 weeks of treatment (n = 32) (0.103 ± 0.081 vs. 0.040 ± 0.048 mMmm, p < 0.001). In the l-carnitine group, 35.4% (17/48) of patients had hyperammonemia. The NIRS data of the l-carnitine group at 8 weeks of treatment were significantly improved than that of the control group, irrespective of baseline ammonia levels (0.11 ± 0.09 vs. 0.04 ± 0.05 mMmm, p = 0.005, and 0.10 ± 0.06 vs. 0.02 ± 0.03 mMmm, p = 0.003, for normal baseline ammonia and elevated ammonia levels, respectively). In the multivariate analysis, l-carnitine administration (odds ratio [OR] 3.51, 95% confidence interval [CI] 1.23–9.99, p = 0.019) and baseline NIRS data of ≤ 0.07 mMmm (OR 5.21, 95% CI 1.69–16.0, p = 0.0041) were found as independent significant factors. l-carnitine improves impaired brain function in patients with liver cirrhosis.

Effect of Resveratrol on Thioacetamide-induced Liver Damage in Rat Models

Background: The current treatments of liver diseases are not sufficiently effective, and there has been no therapy that can successfully prevent liver failure and its complications. Previous studies have suggested that resveratrol could inhibit the progression of hepatic diseases based on its antioxidative and anti-inflammatory potentials. Objectives: The present study evaluated the hepato-protective effects of resveratrol in thioacetamide (TAA)-induced acute liver damage in rats using neurobehavioral and biochemical parameters. Methods: Forty-eight healthy adult Wistar rats were divided into four groups: C1: healthy control group, C2: non-treated liver failure, E1: liver failure treated with resveratrol 5 mg/kg/day, and E2: liver failure treated with resveratrol 10 mg/kg/day. Aspartate aminotransferase/alanine aminotransferase (AST/ALT), alkaline phosphatase (Alk), total bilirubin (TB), and plasma-ammonia (NH4) were analyzed, and histopathological evaluations of the specimens were carried out after sacrificing the models. Hepatic encephalopathy (HE) grading, open-field, elevated plus arms, and forced-swimming tests were performed in the study. Results: The resveratrol-treated groups had lower serum concentrations of NH4, ALT, and AST than the C2 group (P < 0.05). The pathological evaluations demonstrated that resveratrol-treated groups had better outcomes in inflammatory cell infiltration, apoptosis, vacuolization, liver tissue necrosis, and liver damage stage than the C2 group (P < 0.05). They also showed lower grades of HE, higher locomotor activity (open-field test), and diminished levels of depression (forced-swimming) when compared to the C2 group (P < 0.05). Conclusions: Resveratrol supplementation can improve liver damage as AST, ALT, NH4, and tissue damages were decreased after administering the agent in TAA-induced liver damage. Resveratrol can also improve the neurobehavioral manifestations in animal models of liver failure.

The Importance of the Fatty Acid Transporter L-Carnitine in Non-Alcoholic Fatty Liver Disease (NAFLD)

L-carnitine transports fatty acids into the mitochondria for oxidation and also buffers excess acetyl-CoA away from the mitochondria. Thus, L-carnitine may play a key role in maintaining liver function, by its effect on lipid metabolism. The importance of L-carnitine in liver health is supported by the observation that patients with primary carnitine deficiency (PCD) can present with fatty liver disease, which could be due to low levels of intrahepatic and serum levels of L-carnitine. Furthermore, studies suggest that supplementation with L-carnitine may reduce liver fat and the liver enzymes alanine aminotransferase (ALT) and aspartate transaminase (AST) in patients with Non-Alcoholic Fatty Liver Disease (NAFLD). L-carnitine has also been shown to improve insulin sensitivity and elevate pyruvate dehydrogenase (PDH) flux. Studies that show reduced intrahepatic fat and reduced liver enzymes after L-carnitine supplementation suggest that L-carnitine might be a promising supplement to improve or delay the progression of NAFLD.

Usefulness of Carnitine Supplementation for the Complications of Liver Cirrhosis

Carnitine is a vitamin-like substance that regulates lipid metabolism and energy production. Carnitine homeostasis is mainly regulated by dietary intake and biosynthesis in the organs, including the skeletal muscle and the liver. Therefore, liver cirrhotic patients with reduced food intake, malnutrition, biosynthetic disorder, and poor storage capacity of carnitine in the skeletal muscle and liver are more likely to experience carnitine deficiency. In particular, liver cirrhotic patients with sarcopenia are at a high risk for developing carnitine deficiency. Carnitine deficiency impairs the important metabolic processes of the liver, such as gluconeogenesis, fatty acid metabolism, albumin biosynthesis, and ammonia detoxification by the urea cycle, and causes hypoalbuminemia and hyperammonemia. Carnitine deficiency should be suspected in liver cirrhotic patients with severe malaise, hepatic encephalopathy, sarcopenia, muscle cramps, and so on. Importantly, the blood carnitine level does not always decrease in patients with liver cirrhosis, and it sometimes exceeds the normal level. Therefore, patients with liver cirrhosis should be treated as if they are in a state of relative carnitine deficiency at the liver, skeletal muscle, and mitochondrial levels, even if the blood carnitine level is not decreased. Recent clinical trials have revealed the effectiveness of carnitine supplementation for the complications of liver cirrhosis, such as hepatic encephalopathy, sarcopenia, and muscle cramps. In conclusion, carnitine deficiency is not always rare in liver cirrhosis, and it requires constant attention in the daily medical care of this disease. Carnitine supplementation might be an important strategy for improving the quality of life of patients with liver cirrhosis.

Novel Therapies in Hepatic Encephalopathy

Despite widespread use of lactulose and rifaximin for the treatment of hepatic encephalopathy, this complication of advanced liver disease remains a major burden on the health care system in the United States and continues to predispose to high morbidity and mortality. Several agents have surfaced over recent years with promise to treat hepatic encephalopathy and mitigate the cognitive impairment associated with this disease process. The purpose of this article is to highlight the leading emerging therapies in hepatic encephalopathy as well as their therapeutic targets.

Blood carnitine profiling on tandem mass spectrometry in liver cirrhotic patients

BACKGROUND

The level and profiles of blood free carnitine and acylcarnitines, obtained by acylcarnitine analysis using tandem mass spectrometry, reflect various metabolic conditions. We aimed to examine the level of free carnitine and acylcarnitines in liver cirrhosis patients by acylcarnitine analysis and determine the clinical and subjective factors associated with blood carnitine fraction levels in liver cirrhosis.

METHODS

We compared blood carnitine fractions in 54 liver cirrhotic patients to other laboratory test results and questionnaire answers.

RESULTS

In almost all patients, the blood levels of free carnitine (C0) and acetylcarnitine (C2) were within the normal reference range. However, in some patients, the levels of long-chain acylcarnitines, such as C16 and C18:1-acylcarnitine, were higher than the normal reference range. Liver function, assessed by Child-Pugh score, was significantly correlated with the blood level of each carnitine fraction measured (C0, C2, C3, C4, C6, C10, C12, C12:1, C14:1, C16, C18:1, and C18:2-acylcarnitine). Cirrhotic symptom score was significantly correlated with C0, C2, C3, C16, and C18-1-acylcarnitine blood levels. Among the 36-item short-form health survey (SF-36) items, the physical component summary was significantly associated with C0, C2, and C18-1-acylcarnitine blood levels.

CONCLUSIONS

Carnitine fraction levels were positively correlated with liver cirrhosis stage, particularly, long-chain acylcarnitines. Moreover, carnitine fraction levels were associated with various subjective physical symptoms in liver cirrhosis patients.

Effect of L-carnitine on liver enzymes and biochemical factors in hepatic encephalopathy: A systematic review and meta-analysis

BACKGROUND AND AIMS

We aimed to investigate the effect of L-carnitine on biochemical factors including ammonia, bilirubin, albumin, alanine aminotransferase, aspartate aminotransferase (AST), blood urea nitrogen (BUN), and creatinine (Cr) in patients with hepatic encephalopathy (HE).

METHODS

A systematic search was carried out in Web of Science, PubMed, Scopus, and Cochrane Library databases to find articles related to the effect of L-carnitine supplementation in patients with HE, up to 7 February 2019. There was no language and time limitation. Meta-analyses were carried out using both the random and fixed effects models where appropriate, and I² index was used to evaluate the heterogeneity.

RESULTS

Search yielded 3462 publications. Nine randomized clinical trials with 779 patients were eligible. L-carnitine supplementation significantly reduced blood levels of ammonia. Furthermore, our results indicated that L-carnitine supplementation significantly reduced blood levels of bilirubin, AST, BUN, and Cr in patients with HE. Subgroup analysis demonstrated that L-carnitine significantly reduced ammonia in patients with all the ages, long and short duration of the supplementation, doses less or higher than 4000 mg/day, any route of treatment (intravenous or oral), and in patients with any grade of the symptoms of HE. Moreover, we found that L-carnitine significantly increased circulating levels of albumin in HE patients.

CONCLUSIONS

Present systematic review and meta-analysis revealed that L-carnitine supplementation significantly reduced blood levels of ammonia, bilirubin, AST, BUN, and Cr in HE patients. Moreover, we found that L-carnitine significantly increased circulating levels of albumin. However, further large-scale randomized clinical trials are needed.

A Callosal Catastrophe: Toxic Leukoencephalopathy Associated with Thermogenic Weight Loss Supplement Use

BACKGROUND

The use of weight loss drugs and dietary supplements is common, but safety profiles for these drugs are largely unknown. Reports of toxicity have been published, and the use of these agents should be considered in clinical differential diagnoses.

METHODS

We report the case of a patient with toxic leukoencephalopathy and hyponatremia associated with oral consumption of a thermogenic dietary supplement and essential oils.

RESULTS

A 30-year-old woman presented after 2 days of headache, blurred vision, photophobia, vomiting, and hand spasms. She was taking a thermogenic dietary supplement daily for 6 months as well as a number of essential oils. Examination revealed mild right sided ataxia and diffuse hyperreflexia. Neuroimaging demonstrated bilaterally symmetric T2 hyperintensities of the corpus callosum and periventricular white matter. Approximately 18 h after admission she became unresponsive with brief extensor posturing and urinary incontinence. She partially recovered, but 1 h later became unresponsive with dilated nonreactive pupils and extensor posturing (central herniation syndrome). She was intubated, hyperventilated, and given hyperosmotic therapy. Emergent imaging showed diffuse cerebral edema. Intracranial pressure was elevated but normalized with treatment; she regained consciousness the following day. She was extubated one day later and discharged on hospital day 5. She was seen 2 months later with no further symptoms and a normal neurologic examination.

CONCLUSIONS

The pathophysiology of this patient's hyponatremia and toxic leukoencephalopathy is unknown. However, physicians must be aware of the association between thermogenic dietary supplements and toxic leukoencephalopathy. Vigilance for life-threatening complications including hyponatremia and cerebral edema is critical.

L-carnitine prevents ammonia-induced cytotoxicity and disturbances in intracellular amino acid levels in human astrocytes

BACKGROUND AND AIM

L-carnitine (L-CA) has been used therapeutically to treat hepatic encephalopathy with hyperammonemia, but the mechanism by which L-CA contributes to ammonia detoxification in the brain is still unclear. Thus, the cytotoxicity and changes in intracellular amino acids (AAs) in astrocytes with hyperammonemia following L-CA administration were studied.

METHODS

Human astrocytes were treated with ammonium chloride (NH₄ Cl), L-CA or a mixture of NH₄ Cl, and L-CA under defined conditions. Total intracellular reactive oxygen species and lactate dehydrogenase leakage were measured following different treatment periods. The intracellular levels of AAs in astrocytes were determined using metabolomic analysis.

RESULTS

Intracellular total reactive oxygen species and lactate dehydrogenase leakage were significantly increased after treatment with NH₄ Cl. In contrast, co-treatment with L-CA significantly inhibited the cytotoxic effects of NH₄ Cl. The intracellular levels of almost all AAs involving glutamine and branched-chain AAs (BCAAs) were significantly increased in the NH₄ Cl-treated cells compared with in the control cells; these changes in BCAA levels were reduced with L-CA co-treatment. Additionally, the level of 3-methyl-2-oxovaleric acid, which is a metabolite from isoleucine and plays a critical role in neurological damage, was significantly increased in the NH₄ Cl-treated cells, but this metabolite was significantly decreased with L-CA co-treatment.

CONCLUSION

L-CA protects human astrocytes from ammonia-induced acute cytotoxic effects and the increased intracellular levels of glutamine and BCAAs.

Erythrocytes as bioreactors to decrease excess ammonium concentration in blood

Increased blood ammonium concentrations cause neurological complications. Existing drugs are not always sufficiently effective. Alternatively, erythrocytes-bioreactors (EBRs) loaded with enzymes utilizing ammonium, were suggested for ammonium removal from blood. However all they worked only for a short period of time. The reasons for this were not investigated. In this study, EBR mathematical models were developed and analysed based on the reactions of glycolysis and different enzymes utilizing ammonium, which showed that the efficiency and duration of EBRs' functioning could be limited due to low permeability of the cell membrane for some key substrates and products. A new enzyme system including glutamate dehydrogenase and alanine aminotransferase was proposed and realised experimentally, which was not limited by cell membrane permeability for glutamate and α-ketoglutarate due to creating metabolic pathway where these metabolites were produced and consumed cyclically. New bioreactors removed ammonium in vitro at the rate of 1.5 mmol/h × lRBCs (for human bioreactors) and in vivo in a model of hyperammoniemia in mice at the rate of 2.0 mmol/h × lRBCs (for mouse bioreactors), which correlated with model calculations. Experimental studies proved the proposed mathematical models are correct. Mathematical simulation of erythrocyte-bioreactors opens new opportunities for analysing the efficiency of any enzyme included in erythrocytes.

CPT2 downregulation adapts HCC to lipid-rich environment and promotes carcinogenesis via acylcarnitine accumulation in obesity

OBJECTIVE

Metabolic reprogramming of tumour cells that allows for adaptation to their local environment is a hallmark of cancer. Interestingly, obesity-driven and non-alcoholic steatohepatitis (NASH)-driven hepatocellular carcinoma (HCC) mouse models commonly exhibit strong steatosis in tumour cells as seen in human steatohepatitic HCC (SH-HCC), which may reflect a characteristic metabolic alteration.

DESIGN

Non-tumour and HCC tissues obtained from diethylnitrosamine-injected mice fed either a normal or a high-fat diet (HFD) were subjected to comprehensive metabolome analysis, and the significance of obesity-mediated metabolic alteration in hepatocarcinogenesis was evaluated.

RESULTS

The extensive accumulation of acylcarnitine species was seen in HCC tissues and in the serum of HFD-fed mice. A similar increase was found in the serum of patients with NASH-HCC. The accumulation of acylcarnitine could be attributed to the downregulation of carnitine palmitoyltransferase 2 (CPT2), which was also seen in human SH-HCC. CPT2 downregulation induced the suppression of fatty acid β-oxidation, which would account for the steatotic changes in HCC. CPT2 knockdown in HCC cells resulted in their resistance to lipotoxicity by inhibiting the Src-mediated JNK activation. Additionally, oleoylcarnitine enhanced sphere formation by HCC cells via STAT3 activation, suggesting that acylcarnitine accumulation was a surrogate marker of CPT2 downregulation and directly contributed to hepatocarcinogenesis. HFD feeding and carnitine supplementation synergistically enhanced HCC development accompanied by acylcarnitine accumulation in vivo.

CONCLUSION

In obesity-driven and NASH-driven HCC, metabolic reprogramming mediated by the downregulation of CPT2 enables HCC cells to escape lipotoxicity and promotes hepatocarcinogenesis.

Recent advances in drug delivery via the organic cation/carnitine transporter 2 (OCTN2/SLC22A5)

INTRODUCTION

Transporters in the plasma membrane have been exploited successfully for the delivery of drugs in the form of prodrugs and nanoparticles. Organic cation/carnitine transporter 2 (OCTN2, SLC22A5) has emerged as a viable target for drug delivery. OCTN2 is a Na⁺-dependent high-affinity transporter for L-carnitine and a Na⁺-independent transporter for organic cations. OCTN2 is expressed in the blood-brain barrier, heart, liver, kidney, intestinal tract and placenta and plays an essential role in L-carnitine homeostasis in the body. Areas covered: In recent years, several studies have been reported in the literature describing the utility of OCTN2 to enhance the delivery of drugs, prodrugs and nanoparticles. Here we summarize the salient features of OCTN2 in terms of its role in the cellular uptake of its physiological substrate L-carnitine in physiological and pathological context; the structural requirements for recognition and the recent advances in OCTN2-targeted drug delivery systems, including prodrugs and nanoparticles, are discussed. Expert opinion: This transporter has great potential to be utilized as a target for drug delivery to improve oral absorption of drugs in the intestinal tract. It also has potential to facilitate the transfer of drugs across the biological barriers such as the blood-brain barrier, blood-retinal barrier, and maternal-fetal barrier.

Hepatic encephalopathy: Diagnosis and management

Hepatic encephalopathy (HE) is a peculiar kind of brain dysfunction caused by liver insufficiency and/or portal-systemic shunting. It is related to gut-derived substances. It is a relevant cause of morbidity and hospitalisation for patients with cirrhosis. The prognosis of HE is important in terms of survival and re-hospitalisation. It is related to impaired quality of life, falls and poor driving; presents a relevant burden for caregivers and health services; and may negatively impact on patient's job and income. Proper diagnosis and classification are expected to improve HE management. Once diagnosed, the management and therapeutic options for HE are generally clear. The improvement of knowledge in recent years has also clarified which are the further aims of research in this field of medicine. Prophylaxis of overt HE should always be performed, and this is generally secondary prophylaxis. Primary prophylaxis should be done immediately after upper gastrointestinal bleeding. Great advances in the detection and treatment of mild forms of HE are expected to lead to further improvement in patient management.

BBOX1 is down-regulated in maternal immune-activated mice and implicated in genetic susceptibility to human schizophrenia

Prenatal exposure to infectious or inflammatory insults can increase the risk of developing neuropsychiatric disorders such as bipolar disorder, autism, and schizophrenia in later life. Gamma-butyrobetaine hydroxylase (BBOX 1) is an enzyme responsible for the biosynthesis of l-carnitine, a key molecule in fatty acid metabolism. This cytosolic dimeric protein belongs to the dioxygenase family. In this study, we investigated whether BBOX 1 expression was related to psychiatric disorder in an animal model. We also conducted a case-control study using 284 schizophrenia patients and 409 controls with single-nucleotide polymorphisms (SNPs) in the 5'-near region of BBOX 1. BBOX 1 expression was increased in the medial frontal cortex of a mouse model of schizophrenia induced by maternal immune activation. Furthermore, the genotype and allele frequencies of two SNPs (rs7939644 and rs10767592) were significantly associated with schizophrenia susceptibility. Our results suggest that BBOX 1 might be associated with maternal immune activation and schizophrenia susceptibility. Therefore, it might be involved in the pathophysiology of schizophrenia.

L-Carnitine for the Treatment of Overt Hepatic Encephalopathy in Patients with Advanced Liver Cirrhosis

Hepatic encephalopathy is a major complication in patients with advanced cirrhosis and is associated with poor prognosis. To evaluate the effectiveness of L-carnitine supplementation in patients with overt hepatic encephalopathy (OHE), outcomes were retrospectively analyzed in patients with OHE who were treated with intravenous branched-chain amino acids (BCAA), with or without intravenous L-carnitine. Twenty-six patients were treated with intravenous BCAA in addition to conventional agents such as lactulose and non-absorbable antibiotics (Group A), and 19 patients were treated with these agents plus intravenous L-carnitine (Group L). Changes in blood ammonia concentrations, hepatic coma grade and the Glasgow Coma Scale (GCS) were compared in the two groups. Recurrence-free survival (RFS) was evaluated in the two groups and in patients who were and were not administered oral L-carnitine supplementation. At baseline, GCS scores were significantly lower and deterioration in liver function greater in Group L. After 3 d of intravenous L-carnitine, however, GCS showed a significantly greater improvement in Group L than in Group A. Blood ammonia levels improved stably over time in Group L. Overall survival and RFS were similar in Group L and Group A, but median RFS was significantly longer in patients who did than did not receive oral L-carnitine supplementation (735 versus 497 d, p=0.03). Although these findings are preliminary, L-carnitine supplementation may be a therapeutic option for patients with OHE and disturbed consciousness.

Ammonia-induced mitochondrial dysfunction and energy metabolism disturbances in isolated brain and liver mitochondria, and the effect of taurine administration: relevance to hepatic encephalopathy treatment

INTRODUCTION

Ammonia-induced oxidative stress, mitochondrial dysfunction, and energy crisis are known as some the major mechanisms of brain injury in hepatic encephalopathy (HE). Hyperammonemia also affects the liver and hepatocytes. Therefore, targeting mitochondria seems to be a therapeutic point of intervention in the treatment of HE. Taurine is an abundant amino acid in the human body. Several biological functions including the mitochondrial protective properties are attributed to this amino acid. The aim of this study is to evaluate the effect of taurine administration on ammonia-induced mitochondrial dysfunction.

MATERIAL AND METHODS

Isolated mice liver and brain mitochondria were exposed to different concentrations of ammonia (1, 5, 10, and 20 mM) and taurine (1, 5, and 10 mM), and several mitochondrial indices were assessed.

RESULTS

It was found that ammonia inhibited mitochondrial dehydrogenases activity caused collapse of mitochondrial membrane potential (MMP), induced mitochondrial swelling (MPP), and increased reactive oxygen species (ROS) in isolated liver and brain mitochondria. Furthermore, a significant amount of lipid peroxidation (LPO), along with glutathione (GSH) and ATP depletion, was detected in ammonia exposed mitochondria. Taurine administration (5 and 10 mM) mitigated ammonia-induced mitochondrial dysfunction.

CONCLUSIONS

The current investigation demonstrates that taurine is instrumental in preserving brain and liver mitochondrial function in a hyperammonemic environment. The data suggest taurine as a potential protective agent with a therapeutic capability against hepatic encephalopathy and hyperammonemia.

Carnitine dynamics and their effects on hyperammonemia in cirrhotic Japanese patients

AIM

Supplementation with levocarnitine preparations has been reported to improve hepatic encephalopathy, but no detailed investigations have addressed the dynamics of carnitine or its supplementation indication in cirrhosis patients. We studied carnitine dynamics in cirrhotic patients by measuring serum and liver tissue carnitine levels and tested the effects of levocarnitine supplementation on concurrent hyperammonemia.

METHODS

In a pilot cohort of seven patients with liver cirrhosis and five patients without cirrhosis, the serum and liver carnitine concentrations were measured. Then the serum carnitine fractions were analyzed in 70 liver cirrhosis patients. Among them, a levocarnitine preparation (1800 mg/day) was supplemented orally for 3 months in 27 patients with refractory hyperammonemia, and the effects were evaluated.

RESULTS

A significant correlation was observed between serum and liver tissue carnitine concentrations (r = 0.69, P < 0.05). The serum total carnitine concentration was 68.4 ± 4.7 μmol/L, the free carnitine concentration was 53.2 ± 2.6 μmol/L, and the acylcarnitine concentration was 13.2 ± 1.1 μmol/L in 70 cirrhotic patients (reference values are 45-91, 36-74, 6-23 μmol/L, respectively). There was no correlation between blood ammonia and serum carnitine concentrations. The serum carnitine concentration rose with levocarnitine supplementation, reaching steady state after 1 month and, in parallel, refractory hyperammonemia was significantly improved. The cut-off level for a 20% decrease in blood ammonia was identified as 62.0 μmol/L total carnitine concentration by receiver-operating characteristic curve analysis, with an area under the curve of 0.69.

CONCLUSION

Serum carnitine concentrations were within standard levels in the majority of liver cirrhosis patients. In patients with concurrent hyperammonemia, the levocarnitine supplementation reduced blood ammonia levels.

Cerebrospinal fluid metabolomics highlights dysregulation of energy metabolism in overt hepatic encephalopathy

BACKGROUND & AIMS

Hepatic encephalopathy (HE) is a neurological complication observed in patients with liver disease and/or porto-systemic shunt. The proportion of cirrhotic patients developing overt HE is about 20%, and 60-80% of cirrhotic patients exhibit mild cognitive impairment potentially related to minimal HE. However, the pathophysiological mechanisms of HE remain poorly understood. In this context, metabolomics was used to highlight dysfunction of metabolic pathways in cerebrospinal fluid (CSF) samples of patients suffering from HE.

METHODS

CSF samples were collected in 27 control patients without any proven neurological disease and 14 patients with symptoms of HE. Plasma samples were obtained from control patients, and from cirrhotic patients with and without HE. Metabolomic analysis was performed using liquid chromatography coupled to high-resolution mass spectrometry.

RESULTS

Concentrations of 73 CSF metabolites, including amino acids, acylcarnitines, bile acids and nucleosides, were altered in HE patients. Accumulation of acetylated compounds, which could be due to a defect of the Krebs cycle in HE patients, is reported for the first time. Furthermore, analysis of plasma samples showed that concentrations of metabolites involved in ammonia, amino-acid and energy metabolism are specifically and significantly increased in CSF samples of HE patients. Lastly, several drugs were detected in CSF samples and could partially explain worsening of neurological symptoms for some patients.

CONCLUSION

By enabling the simultaneous monitoring of a large set of metabolites in HE patients, CSF metabolomics highlighted alterations of metabolic pathways linked to energy metabolism that were not observed in plasma samples.

LAY SUMMARY

CSF metabolomics provides a global picture of altered metabolic pathways in CSF samples of HE patients and highlights alterations of metabolic pathways linked to energy metabolism that are not observed in plasma samples.

L-carnitine Reduces Muscle Cramps in Patients With Cirrhosis

We performed a prospective study to evaluate the ability of L-carnitine, which is involved in the β-oxidation of fatty acids, to reduce muscle cramps in patients with cirrhosis. Consecutive patients with cirrhosis and muscle cramps were given L-carnitine 300 mg, 3 times/day (900 mg/day, n = 19) or 4 times/day (1200 mg/day, n = 23) for 8 weeks. The frequency of muscle cramps was assessed by questionnaires, and the degree of muscle cramping was assessed by using the visual analogue scale (VAS). Muscle cramping was reduced in 88.1% of all subjects at the end of the 8-week study period and disappeared for 28.6% of patients. Overall VAS scores decreased significantly from 69.9 ± 22.5 at baseline to 26.2 ± 29.1 after 8 weeks (P < .0001). The dose of L-carnitine was significantly associated with percentages of patients with reduced muscle cramps after 8 weeks (43.5% in the 1200 mg/day group vs 10.5% in the 900 mg/day group, P = .037) and VAS scores at 8 weeks (9.9 ± 13.5 in the 1200 mg/day group vs 39.6 ± 31.9 in the 900 mg/day group, P = .003). No adverse events were reported. Therefore, L-carnitine appears to be safe and effective for reducing liver cramps in patients with cirrhosis.

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.

Oral acetyl-L-carnitine treatment in hepatic encephalopathy: view of evidence-based medicine

OBJECTIVE

To systematically review the effect of acetyl-L-carnitine in patients with hepatic encephalopathy.

DESIGN

systematic review and meta-analysis.

DATA SOURCES

The Cochrane Library, MEDLINE, EMBASE.com, Science Citation Index, Google search and the China Biological Medicine Database to June 2012.

REVIEW METHODS

randomized placebo controlled trials of acetyl-L-carnitine in patients with hepatic encephalopathy assessing whether acetyl-L-carnitine is an effective therapy or not. No language restrictions were applied. Two reviewers independently extracted data and assessed quality.

RESULTS

7 methodologically sound randomized controlled trials were identified involving 660 participants with hepatic encephalopathy, totaling 249 with subclinical hepatic encephalopathy, 189 with West Haven grade 1, 162 with West Haven grade 2 and 60 with West Haven grade 3. Acetyl-L-carnitine was effective to improve serum ammonia level (weighted mean difference 25.90, 95% confidence intervals 20.89 to 30.91, P < 0.05) and the number connection test completion time (weighted mean difference 16.62, 95% confidence intervals 9.88 to 23.36, P < 0.05). The outcome was consistent in subgroup analyses. No publication bias was detected. Adverse events were reported infrequently and were minor.

CONCLUSIONS

Acetyl-L-carnitine is promising as an effective and tolerable treatment for hepatic encephalopathy that associated with improved serum ammonia levels and the number connection test.

Impact on L-carnitine Homeostasis of Short-term Treatment with the Pivalate Prodrug Tenofovir Dipivoxil

Pivalate-generating prodrugs have been suggested to cause clinically significant hypocarnitinaemia. Tenofovir dipivoxil, a novel ester prodrug of tenofovir, can be used for treatment for hepatitis B and HIV infection and it was necessary to evaluate the effect of its treatment on carnitine homeostasis. We sought to investigate the effect of Class 1 drug tenofovir dipivoxil on endogenous L-carnitine level during a 72-hr test in healthy Chinese volunteers and to establish a suitable dose of L-carnitine nutritional supplement for patients who were administered short-term tenofovir dipivoxil tablets for treatment for hepatitis B and herpes simplex virus infection. Tenofovir dipivoxil was administered in one of eight dosing regimens (single dose 150, 300 and 600 mg, multiple dose 300, 450, and 600 mg, multiple dose 450 (600) mg tenofovir dipivoxil and 0.5 g L-carnitine) to gender-balanced groups of 84 healthy Chinese volunteers. Plasma concentrations of L-carnitine were quantified before, during and after treatment. Plasma L-carnitine concentrations fell during tenofovir dipivoxil dosing. The nadir in L-carnitine concentration was dependent on the dose of tenofovir dipivoxil and it decreased from 6.1 ± 0.6 to 4.4 ± 0.8 μg/ml, 6.1 ± 1.8 to 3.3 ± 1.2 μg/ml, 6.2 ± 0.6 to 2.5 ± 0.5 μg/ml for single doses of 150, 300, 600 mg tenofovir dipivoxil tablets and from 6.0 ± 1.4 to 2.1 ± 1.5 μg/ml, 6.2 ± 0.4 to 0.9 ± 0.5 μg/ml for multiple doses of 450, 600 mg tenofovir dipivoxil tablets, respectively. Short-term administration of tenofovir dipivoxil results in hypocarnitinaemia and increased losses of carnitine in resulting of minor adverse events of decreased food appetite, nausea, abdominal distention and muscle weakness.

Serum carnitine levels and levocarnitine supplementation in institutionalized Huntington's disease patients

Along with antioxidant properties, carnitine is an important regulator of lipid metabolism in humans. While beneficial effects of carnitine have been demonstrated in animal models of Huntington's disease (HD), metabolism of carnitine has not been studied in humans with this illness. In this retrospective database review from 23 patients admitted to a HD-specialized nursing home unit, we found a relatively high prevalence of hypocarnitinemia (6 cases, 26%). Our review suggests that catabolism and chronic valproate use predisposed our patients to develop hypocarnitinemia. The patients with low serum carnitine levels who received levocarnitine supplementation, during a mean period of 7.3 months, showed improvement in motor, cognitive and behavioral measures. We hypothesize that observed improvement related to the resolution of reversible metabolic encephalopathy and myopathy associated with secondary carnitine deficiency. In conclusion, notwithstanding its limitations, this is the first study to report measurements of carnitine levels in HD patients, revealing relatively high prevalence of hypocarnitinemia in our population. Our findings suggest that HD patients with hypocarnitinemia may benefit from low-dose levocarnitine supplementation. Further studies of carnitine metabolism and supplementation in HD patients are warranted.

Treatment with a potassium-iron-phosphate-citrate complex improves PSE scores and quality of life in patients with minimal hepatic encephalopathy: a multicenter, randomized, placebo-controlled, double-blind clinical trial

OBJECTIVE

Minimal hepatic encephalopathy (MHE) is one of the possible complications of liver cirrhosis. In this study, a potassium-iron-phosphate-citrate complex was analyzed for its efficacy and safety in the treatment of MHE, as this complex is supposed to bind to the major pathogenic factor of MHE: intestinal ammonia.

MATERIALS AND METHODS

In this placebo-controlled, double-blind clinical trial, 51 patients with MHE were randomized into two groups at a ratio of 1 : 1 and treated for 4 weeks either with a potassium-iron-phosphate-citrate complex or a placebo. The efficacy of treatment was assessed according to changes in the portosystemic encephalopathy (PSE) score. Further assessments included alterations in quality of life and safety evaluations.

RESULTS

Significantly more patients showed improvements in the PSE syndrome test from pathological to nonpathological PSE scores in the potassium-iron-phosphate-citrate-treated group (72.0%) than in the placebo group (26.9%; P=0.0014). Furthermore, quality of life improved at a higher grade in the verum group (by 0.7 ± 0.6 U) compared with the placebo group (by 0.2 ± 0.6 U; P=0.0036). Adverse events occurring in 28.0% of potassium-iron-phosphate-citrate-treated patients were generally mild or moderate and affected mainly the gastrointestinal tract.

CONCLUSION

Treatment with potassium-iron-phosphate-citrate significantly improved PSE scores and quality of life in patients with MHE. The potassium-iron-phosphate-citrate complex is a well-tolerated treatment option in MHE.

Hepatic encephalopathy: a review of its pathophysiology and treatment

Hepatic encephalopathy (HE) is a broad spectrum of neuropsychiatric manifestations usually affecting individuals with end-stage liver disease. The presence of HE is a poor prognostic sign, with 1-year mortality rates of almost 60%. There is much debate about the underlying mechanisms that result in this syndrome; however, elevated plasma and central nervous system ammonia levels are considered key factors in its pathogenesis. Initial evaluation of the patient presenting with overt HE should include a careful search for predisposing factors, including underlying infection, gastrointestinal (GI) bleeding, electrolyte disturbances, hepatocellular carcinoma, dehydration, hypotension, and excessive use of benzodiazepines, psychoactive drugs, or alcohol. The mainstay of treatment for many years has been nonabsorbable disaccharides, particularly lactulose. Alternative treatments, which usually are second line in patients who do not respond to lactulose, include zinc, antibiotics (neomycin, metronidazole, and rifaximin), ornithine aspartate, sodium benzoate, probiotics, and surgical intervention. Accepted treatments for HE are associated with significant unpleasant side effects, including diarrhea, renal failure, neuropathy, and other GI disturbance. Newer therapies are still in development, and most are awaiting human trials in order to confirm their benefit. These include manganese chelators, L-carnitine, N-methyl-d-aspartate receptor antagonists, blood purification dialysis system, and an intravenous combination of sodium benzoate and phenylacetate.

Ammonia-lowering strategies for the treatment of hepatic encephalopathy

Hyperammonemia leads to neurotoxic levels of brain ammonia and is a major factor involved in the pathogenesis of hepatic encephalopathy (HE). Ammonia-lowering treatments primarily involve two strategies: inhibiting ammonia production and/or increasing ammonia removal. Targeting the gut has been the primary focus for many years, with the goal of inhibiting the generation of ammonia. However, in the context of liver failure, extrahepatic organs containing ammonia metabolic pathways have become new potential ammonia-lowering targets. Skeletal muscle has the capacity to remove ammonia by producing glutamine through the enzyme glutamine synthetase (amidation of glutamate) and, given its large mass, has the potential to be an important ammonia-removing organ. On the other hand, glutamine can be deaminated to glutamate by phosphate-activated glutaminase, thus releasing ammonia (ammonia rebound). Therefore, new treatment strategies are being focused on stimulating the removal of both ammonia and glutamine.