Review

Authors: Huann Lan Tan, Jared G Smith, Jan Hoffmann...

BACKGROUND

Burning mouth syndrome is a chronic idiopathic intractable intraoral dysaesthesia that remains a challenge to clinicians due to its poorly understood pathogenesis and inconsistent response to various treatments.

AIM

This review aimed to study the short- (≤3 months) and long-term (>3 months) effectiveness and sustainable benefit of different burning mouth syndrome treatment strategies and the associated side effects.

MATERIALS AND METHODS

Randomised controlled trials of burning mouth syndrome treatment compared with placebo or other interventions with a minimum follow up of 2 months were searched from the PubMed, Embase and Cochrane database (published to July 2020).

RESULTS

Twenty-two studies were selected based on the inclusion and exclusion criteria and analysed. Nine categories of burning mouth syndrome treatment were identified: Anticonvulsant and antidepressant agents, phytomedicine and alpha lipoic acid supplements, low-level laser therapy, saliva substitute, transcranial magnetic stimulation, and cognitive behaviour therapy. Cognitive behaviour therapy, topical capsaicin and clonazepam, and laser therapy demonstrated favourable outcome in both short- and long-term assessment. Phytomedicines reported a short-term benefit in pain score reduction. The pooled effect of alpha lipoic acid (ALA) pain score improvement was low, but its positive effects increased in long term assessment.

CONCLUSION

A more significant volume in terms of sample size, multi-centres, and multi-arm comparison of therapeutic agents with placebo and longitudinal follow-up studies is recommended to establish a standardised burning mouth syndrome treatment protocol. Further studies are required to assess the analgesic benefits of topical clonazepam and capsaicin, alternative medicines with neurodegenerative prevention capability and psychology support in treating burning mouth syndrome and reducing systemic adverse drug reactions. International Prospective Register of Systematic Reviews (PROSPERO):Protocol ID - CRD42020160892.

Topics: Burning Mouth Syndrome; Capsaicin; Clonazepam; Humans; Pain; Thioctic Acid

PubMed: 34404247
DOI: 10.1177/03331024211036152

Review

Authors: Umberto Capece, Simona Moffa, Ilaria Improta...

Alpha-lipoic acid (ALA) is a natural compound with antioxidant and pro-oxidant properties which has effects on the regulation of insulin sensitivity and insulin secretion. ALA is widely prescribed in patients with diabetic polyneuropathy due to its positive effects on nerve conduction and alleviation of symptoms. It is, moreover, also prescribed in other insulin resistance conditions such as metabolic syndrome (SM), polycystic ovary syndrome (PCOS) and obesity. However, several cases of Insulin Autoimmune Syndrome (IAS) have been reported in subjects taking ALA. The aim of the present review is to describe the main chemical and biological functions of ALA in glucose metabolism, focusing on its antioxidant activity, its role in modulating insulin sensitivity and secretion and in symptomatic peripheral diabetic polyneuropathy. We also provide a potential explanation for increased risk for the development of IAS.

Topics: Female; Humans; Thioctic Acid; Insulin Resistance; Diabetic Neuropathies; Antioxidants; Polycystic Ovary Syndrome; Autoimmune Diseases; Glucose

PubMed: 36615676
DOI: 10.3390/nu15010018

Review

Authors: Ashley Solmonson, Ralph J DeBerardinis

Lipoic acid is an essential cofactor for mitochondrial metabolism and is synthesized using intermediates from mitochondrial fatty-acid synthesis type II, -adenosylmethionine and iron-sulfur clusters. This cofactor is required for catalysis by multiple mitochondrial 2-ketoacid dehydrogenase complexes, including pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, and branched-chain ketoacid dehydrogenase. Lipoic acid also plays a critical role in stabilizing and regulating these multienzyme complexes. Many of these dehydrogenases are regulated by reactive oxygen species, mediated through the disulfide bond of the prosthetic lipoyl moiety. Collectively, its functions explain why lipoic acid is required for cell growth, mitochondrial activity, and coordination of fuel metabolism.

Topics: Animals; Energy Metabolism; Humans; Lipid Metabolism; Mitochondria; Oxidation-Reduction; Thioctic Acid

PubMed: 29191830
DOI: 10.1074/jbc.TM117.000259

Review

Authors: Dan Ziegler

Diabetic peripheral neuropathy (DPN) is found in around one third of people with diabetes, but remains inadequately diagnosed and treated. Its management includes three cornerstones: 1) causal treatment with lifestyle modification, intensive diabetes therapy aimed at near-normoglycemia, and multifactorial cardiovascular risk intervention, 2) pathogenesis-oriented pharmacotherapy, and 3) symptomatic pain relief. Since symptomatic analgesic monotherapy only relieves the pain without targeting the underlying neuropathy and both has limited efficacy and is associated with adverse events, there is an unmet need for additional approaches derived from the pathogenetic concepts of DPN. Preclinical studies have suggested that diabetic neuropathy can be prevented or improved through the use of various agents that interfere with the pathophysiology of the underlying condition. Some of these encouraging findings could be translated successfully into the clinical setting. Efficacy and excellent safety were demonstrated in several meta-analyses (α-lipoic acid) and randomized clinical trials (benfotiamine, actovegin, epalrestat) in the treatment of symptomatic DPN. The NATHAN 1 trial demonstrated an improvement of neuropathic signs (deficits, impairments) after four years in asymptomatic DPN. These compounds are currently authorized for treatment of DPN in several countries. Long-term pivotal clinical trials should further establish their value as mono- and combination therapies in DPN.

Topics: Humans; Combined Modality Therapy; Diabetes Mellitus; Diabetic Neuropathies; Pain; Thioctic Acid

PubMed: 38245327
DOI: 10.1016/j.diabres.2023.110764

Review

Authors: Riley J Wedan, Jacob Z Longenecker, Sara M Nowinski...

Contrary to their well-known functions in nutrient breakdown, mitochondria are also important biosynthetic hubs and express an evolutionarily conserved mitochondrial fatty acid synthesis (mtFAS) pathway. mtFAS builds lipoic acid and longer saturated fatty acids, but its exact products, their ultimate destination in cells, and the cellular significance of the pathway are all active research questions. Moreover, why mitochondria need mtFAS despite their well-defined ability to import fatty acids is still unclear. The identification of patients with inborn errors of metabolism in mtFAS genes has sparked fresh research interest in the pathway. New mammalian models have provided insights into how mtFAS coordinates many aspects of oxidative mitochondrial metabolism and raise questions about its role in diseases such as obesity, diabetes, and heart failure. In this review, we discuss the products of mtFAS, their function, and the consequences of mtFAS impairment across models and in metabolic disease.

Topics: Animals; Humans; Mitochondria; Cell Respiration; Fatty Acids; Thioctic Acid; Oxidative Stress; Mammals

PubMed: 38128528
DOI: 10.1016/j.cmet.2023.11.017

Review

Authors: Bahare Salehi, Yakup Berkay Yılmaz, Gizem Antika...

α-lipoic acid (ALA, thioctic acid) is an organosulfur component produced from plants, animals, and humans. It has various properties, among them great antioxidant potential and is widely used as a racemic drug for diabetic polyneuropathy-associated pain and paresthesia. Naturally, ALA is located in mitochondria, where it is used as a cofactor for pyruvate dehydrogenase (PDH) and α-ketoglutarate dehydrogenase complexes. Despite its various potentials, ALA therapeutic efficacy is relatively low due to its pharmacokinetic profile. Data suggests that ALA has a short half-life and bioavailability (about 30%) triggered by its hepatic degradation, reduced solubility as well as instability in the stomach. However, the use of various innovative formulations has greatly improved ALA bioavailability. The R enantiomer of ALA shows better pharmacokinetic parameters, including increased bioavailability as compared to its S enantiomer. Indeed, the use of amphiphilic matrices has capability to improve ALA bioavailability and intestinal absorption. Also, ALA's liquid formulations are associated with greater plasma concentration and bioavailability as compared to its solidified dosage form. Thus, improved formulations can increase both ALA absorption and bioavailability, leading to a raise in therapeutic efficacy. Interestingly, ALA bioavailability will be dependent on age, while no difference has been found for gender. The present review aims to provide an updated on studies from preclinical to clinical trials assessing ALA's usages in diabetic patients with neuropathy, obesity, central nervous system-related diseases and abnormalities in pregnancy.

Topics: Animals; Antioxidants; Biological Availability; Central Nervous System Diseases; Diabetic Neuropathies; Humans; Obesity; Thioctic Acid

PubMed: 31405030
DOI: 10.3390/biom9080356

Review

Authors: David Mantle, Iain Parry Hargreaves

Mitochondrial dysfunction has been implicated in the pathogenesis of a number of neurodegenerative disorders, including Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis, multisystem atrophy, and progressive supranuclear palsy. This article is concerned specifically with mitochondrial dysfunction as defined by reduced capacity for ATP production, the role of depleted levels of key nutritionally related metabolites, and the potential benefit of supplementation with specific nutrients of relevance to normal mitochondrial function in the above neurodegenerative disorders. The article provides a rationale for a combination of CoQ10, B-vitamins/NADH, L-carnitine, vitamin D, and alpha-lipoic acid for the treatment of the above neurodegenerative disorders.

Topics: Humans; NAD; Thioctic Acid; Mitochondria; Dietary Supplements; Multiple System Atrophy; Vitamins; Carnitine; Vitamin D; Adenosine Triphosphate

PubMed: 36293457
DOI: 10.3390/ijms232012603

Meta-Analysis Review

Authors: Ruey-Yu Hsieh, I-Chen Huang, Chiehfeng Chen...

Alpha-lipoic acid (ALA) was found to improve the symptoms in patients with diabetic sensorimotor peripheral neuropathy (DSPN) by reducing oxidative stress and ameliorating microcirculation. Our meta-analysis is aimed at evaluating the effects of oral-administered ALA versus a placebo in patients with DSPN and determining the optimal dosage for this treatment. We systematically reviewed randomized controlled trials (RCTs) in the PubMed, Embase, and Cochrane databases to determine the efficacy of oral ALA for patients with DSPN. The primary outcome was total symptoms' score (TSS), and secondary outcomes were the neurological disability score (NDS), neuropathy impaired score (NIS), NIS-lower limb (NIS-LL), vibration perception threshold (VPT), nerve conduction study (NCS) results, and global satisfaction. A subgroup analysis of the ALA dosage (600, 1200, and 1800 mg/day) was also conducted. Ten RCTs (1242 patients) were included. ALA treatment produced favorable results for TSS (a dose-related trend was observed), NDS, and the global satisfaction score. For VAS, VPT, NIS-LL, and NCS results, ALA did not produce favorable results. ALA treatment had favorable effects on DSPN by reducing sensory symptoms, and it resulted in a dose-dependent response relative to the placebo for TSS and the global satisfaction score. The use of ALA to prevent neurological symptoms should be further researched.

Topics: Humans; Diabetic Neuropathies; Thioctic Acid; Administration, Oral; Databases, Factual; Lower Extremity; Diabetes Mellitus

PubMed: 37630823
DOI: 10.3390/nu15163634

Review

Authors: Cristian Baicus, Adrian Purcarea, Erik von Elm...

BACKGROUND

Diabetic peripheral neuropathy (DPN) is a frequent complication in people living with type 1 or type 2 diabetes. There is currently no effective treatment for DPN. Although alpha-lipoic acid (ALA, also known as thioctic acid) is widely used, there is no consensus about its benefits and harms.

OBJECTIVES

To assess the effects of alpha-lipoic acid as a disease-modifying agent in people with diabetic peripheral neuropathy.

SEARCH METHODS

On 11 September 2022, we searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, Embase, and two clinical trials registers. We also searched the reference lists of the included studies and relevant review articles for additional references not identified by the electronic searches.

SELECTION CRITERIA

We included randomised clinical trials (RCTs) that compared ALA with placebo in adults (aged 18 years or older) and that applied the study interventions for at least six months. There were no language restrictions.

DATA COLLECTION AND ANALYSIS

We used standard methods expected by Cochrane. The primary outcome was change in neuropathy symptoms expressed as changes in the Total Symptom Score (TSS) at six months after randomisation. Secondary outcomes were change in neuropathy symptoms at six to 12 months and at 12 to 24 months, change in impairment, change in any validated quality of life total score, complications of DPN, and adverse events. We assessed the certainty of the evidence using GRADE.

MAIN RESULTS

Our analysis incorporated three trials involving 816 participants. Two studies included people with type 1 or type 2 diabetes, while one study included only people with type 2 diabetes. The duration of treatment was between six months and 48 months. We judged all studies at high risk of overall bias due to attrition. ALA compared with placebo probably has little or no effect on neuropathy symptoms measured by TSS (lower score is better) after six months (mean difference (MD) -0.16 points, 95% confidence interval (CI) -0.83 to 0.51; 1 study, 330 participants; moderate-certainty evidence). The CI of this effect estimate did not contain the minimal clinically important difference (MCID) of 0.97 points. ALA compared with placebo may have little or no effect on impairment measured by the Neuropathy Impairment Score-Lower Limbs (NIS-LL; lower score is better) after six months (MD -1.02 points, 95% CI -2.93 to 0.89; 1 study, 245 participants; low-certainty evidence). However, we cannot rule out a significant benefit, because the lower limit of the CI surpassed the MCID of 2 points. There is probably little or no difference between ALA and placebo in terms of adverse events leading to cessation of treatment within six months (risk ratio (RR) 1.48, 95% CI 0.50 to 4.35; 3 studies, 1090 participants; moderate-certainty evidence). No studies reported quality of life or complications associated with DPN.

AUTHORS' CONCLUSIONS

Our analysis suggests that ALA probably has little or no effect on neuropathy symptoms or adverse events at six months, and may have little or no effect on impairment at six months. All the studies were at high risk of attrition bias. Therefore, future RCTs should ensure complete follow-up and transparent reporting of any participants missing from the analyses.

Topics: Adult; Humans; Thioctic Acid; Diabetic Neuropathies; Diabetes Mellitus, Type 2; Lower Extremity; MEDLINE

PubMed: 38205823
DOI: 10.1002/14651858.CD012967.pub2

Review

Authors: Kate Petersen Shay, Régis F Moreau, Eric J Smith...

Alpha-lipoic acid (LA) has become a common ingredient in multivitamin formulas, anti-aging supplements, and even pet food. It is well-defined as a therapy for preventing diabetic polyneuropathies, and scavenges free radicals, chelates metals, and restores intracellular glutathione levels which otherwise decline with age. How do the biochemical properties of LA relate to its biological effects? Herein, we review the molecular mechanisms of LA discovered using cell and animal models, and the effects of LA on human subjects. Though LA has long been touted as an antioxidant, it has also been shown to improve glucose and ascorbate handling, increase eNOS activity, activate Phase II detoxification via the transcription factor Nrf2, and lower expression of MMP-9 and VCAM-1 through repression of NF-kappa B. LA and its reduced form, dihydrolipoic acid, may use their chemical properties as a redox couple to alter protein conformations by forming mixed disulfides. Beneficial effects are achieved with low micromolar levels of LA, suggesting that some of its therapeutic potential extends beyond the strict definition of an antioxidant. Current trials are investigating whether these beneficial properties of LA make it an appropriate treatment not just for diabetes, but also for the prevention of vascular disease, hypertension, and inflammation.

Topics: Animals; Diabetic Neuropathies; Dietary Supplements; Humans; Hypertension; Inflammation; Models, Biological; Molecular Structure; Thioctic Acid; Vascular Diseases

PubMed: 19664690
DOI: 10.1016/j.bbagen.2009.07.026