Efficacy of L-carnitine in reducing hyperammonaemia and improving neuropsychological test performance in patients with hepatic cirrhosis : results of a randomised trial

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.

Effect of L-carnitine on health-related quality of life in patients with liver cirrhosis

L-carnitine (4-N-trimethylammonium-3-hydroxybutyric acid) is the physiologically active form of carnitine and is a natural compound that has been shown to exhibit antioxidant activity. L-carnitine is used as a supplementary treatment in patients with cirrhosis with hepatic encephalopathy, hyperammonemia or muscle cramps. In the present study, the effect of L-carnitine supplementation on health-related quality of life in 30 patients with cirrhosis was prospectively examined. L-carnitine (1,800 mg/day) was administered orally for 6 months. To assess the effects of L-carnitine on chronic fatigue, patients filled out a self-report questionnaire regarding their physical and mental health. The levels of total and free carnitine, and acylcarnitine were found to be significantly higher 1, 3 and 6 months after therapy initiation compared with before treatment. Serum albumin levels were significantly increased 3 and 6 months after initiation of therapy. L-carnitine supplementation significantly increased the BAP/d-ROM ratio, a marker of antioxidant status in patients with cirrhosis. Changes in serum carnitine concentrations were positively correlated with changes in serum albumin levels (R²=0.369; P=0.012), but not with changes in serum ammonia levels (R²= 0.005; P=0.78). Total and mental health scores improved significantly, and physical scores improved marginally 3 and 6 months after initiation of L-carnitine. These findings may be attributed to the enhanced serum albumin levels and oxidative stress rather than the reduced serum ammonia levels. Based on these results, it is suggested that L-carnitine can potentially alleviate chronic fatigue, along with the increased BAP/d-ROM ratio, which were involved in increased oxidative stress in patients with cirrhosis. The specific mechanisms by which L-carnitine ameliorates chronic fatigue is not fully understood and requires further investigation.

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.

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.

Efficacy of L-carnitine on ribavirin-induced hemolytic anemia in patients with hepatitis C virus infection

Background/Aims

L-carnitine not only alleviates hyperammonemia and reduces muscle cramps in patients with liver cirrhosis, but also improves anemia in patients with chronic hepatitis and renal dysfunction. This study prospectively evaluated the preventative efficacy of L-carnitine supplementation against hemolytic anemia during antiviral treatment using ribavirin in patients with hepatitis C virus (HCV)-related chronic liver disease.

Methods

A total of 41 patients with chronic hepatitis were consecutively enrolled in this study. Group A (n=22) received sofosbuvir plus ribavirin for 3 months, whereas group B (n=19) was treated with sofosbuvir, ribavirin, and L-carnitine. Hemoglobin concentration changes, the effects of antiviral treatment, and the health status of patients were analyzed using short form-8 questionnaires.

Results

A significantly smaller decrease in hemoglobin concentration was observed in group B compared to group A at every time point. Moreover, the prescribed dose intensity of ribavirin in group B was higher than that of group A, resulting in a higher ratio of sustained virological response (SVR) 24 in group B compared with group A. The physical function of patients in group B was also significantly improved compared to group A at the end of antiviral treatment.

Conclusions

L-carnitine supplementation alleviates ribavirin-induced hemolytic anemia in patients with HCV and helps relieve the physical burden of treatment with ribavirin-containing regimens. These advantages significantly increase the likelihood of achieving SVR.

Hepatic Encephalopathy in Patients in Lviv (Ukraine)

Background and Objectives

Hepatic encephalopathy (HE) research has long been impeded by the vague definition of this disabling complication of liver failure. This article provides an overview of the etiology and impact of HE on neuromuscular functions as well as its role in the development of infections and anemia.

Materials and Methods

This was a descriptive study conducted in 36 patients with HE. Close monitoring of these patients was done by checking on several parameters.

Results

The etiological distribution: alcohol (67%), hepatitis C virus (HCV; 17%), HCV and alcohol (8%), hepatitis B virus (HBV; 3%), HBV and alcohol (3%), HBV and HCV (6%), and cryptogenic (3%). The laboratory results indicated an elevation of De Ritis level in 69% of cases and in 92% of total bilirubin values. The Halstead-Reitan (H-R) test score with regards to gender indicated that more than half of the patients had a score of 2, while only few cases received the scores 3 and 4. The frequency of H-R score with regards to Child-Pugh score showed the significant preponderance of Child-Pugh score of 7–9 (B): 58.3% compared to others groups of results, and these results indicated patients’ poor prognosis.

Conclusion

Findings showed the preponderance of female patients towards developing HE and the poor survival rate of patients older than 65 years. Alcohol and hepatitis C were the main causes associated with the development of HE. The neurological assessment marked the preponderance of Child-Pugh grades B and C and also the prevalence in female patients with neuropsychological disabilities through the assessment of H-R test.

L-carnitine for cognitive enhancement in people without cognitive impairment

BACKGROUND

Safe interventions to enhance cognitive function in cognitively healthy people would be very valuable for several reasons, including a better quality of life and professional success. While L-carnitine has been reported to enhance cognitive function in some conditions, its efficacy is disputed. The evidence of its efficacy for cognitively healthy people has not previously been systematically reviewed.

OBJECTIVES

To assess the efficacy and safety of L-carnitine for the enhancement of cognitive function in people without cognitive impairment.

SEARCH METHODS

We searched ALOIS, the Cochrane Dementia and Cognitive Improvement Group's Specialized Register, on 4 November 2016. We used the search terms 'L-carnitine' or 'acetyl-L-carnitine' or 'propionyl-L-carnitine' or 'ALC' or 'PLC' or 'ALCAR' or 'ALPAR'. We ran additional separate searches in several other sources to ensure that we retrieved the most up-to-date results. We also reviewed the bibliographies of the randomised controlled trials identified and contacted the authors and known experts in the field and pharmaceutical companies to identify additional published or unpublished data.

SELECTION CRITERIA

Eligible trials were randomised controlled trials (RCTs) or quasi-RCTs, parallel-group or cross-over, that compared L-carnitine or its derivatives, acetyl-L-carnitine or propionyl-L-carnitine, at any dose and for any length of treatment, with placebo or no treatment in cognitively healthy people of any age and either gender.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Two review authors independently selected trials and evaluated the methodological quality, then extracted and analysed data from the included trials.

MAIN RESULTS

Only two RCTs were eligible. One was a cross-over trial with 18 participants. The other randomised 400 participants to one of four treatments, of which two (L-carnitine and placebo) were relevant to this review, but the exact numbers of participants in these two treatment groups was not reported. All participants were young adults. Methodological details were poorly reported, and we considered the risk of bias in both studies to be unclear. The trials assessed different cognitive outcomes. We could extract cognitive data on approximately 200 participants from one trial. We found no evidence that L-carnitine has any effect on reaction time, vigilance, immediate memory, or delayed recall after three days of treatment. This trial report stated that there was a small number of adverse effects, none of which were serious. The small cross-over trial also reported no effect of L-carnitine on cognition, but did not provide data; no information was provided on adverse effects. We considered the available evidence to be of very low quality for all reported outcomes.

AUTHORS' CONCLUSIONS

Due to the limited number of included trials, short-term treatment, and inadequate reporting, we were unable to draw any conclusions about the efficacy or safety of L-carnitine for cognitive enhancement in healthy adults. Well-designed, randomised, placebo-controlled trials of L-carnitine for cognition enhancement in cognitively healthy people, with large samples and relatively long-term follow-up, are still needed.

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.

Is oral L-acyl-carnitine an effective therapy for hepatic encephalopathy? Review of the literature

Hepatic encephalopathy (HE) is a significant cause of morbidity and mortality in patients with advanced chronic liver disease. Current therapies are associated with inconvenient side-effects, high cost, and incomplete efficacy. The quanternary ammonium compound L-acyl-carnitine has been suggested as a potent, low-cost, and safe alternative therapy for patients with cirrhosis and HE. A systematic review of the literature assessing the use of carnitine in the treatment of HE identified three high-quality human trials for review. Analysis of the selected carnitine trials compared to currently accepted therapies suggests that L-acyl-carnitine is promising as a safe and effective treatment for HE, and further trials of this drug are warranted.

An overview of psychiatric issues in liver disease for the consultation-liaison psychiatrist

Liver disease is a common cause of morbidity and mortality in the United States and elsewhere. Arising from infectious, hereditary, or toxin-induced sources, the detection of liver disease often requires a high index of suspicion. Clinical presentations are highly variable and are often accompanied by neuropsychiatric symptoms. This fact, along with an increased incidence of liver disease among patients with primary psychiatric disorders and the presence of varied drug use, complicates the tasks of providing care to patients with liver disease. To assist the consultation-liaison psychiatrist, the authors present the first of a two-part series focused on psychiatric issues in liver disease.