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Molecules (Basel, Switzerland) Jul 2020The γ-aminobutyric acid (GABA) type B receptor (GABA-R) belongs to class C of the G-protein coupled receptors (GPCRs). Together with the GABA receptor, the receptor... (Review)
Review
The γ-aminobutyric acid (GABA) type B receptor (GABA-R) belongs to class C of the G-protein coupled receptors (GPCRs). Together with the GABA receptor, the receptor mediates the neurotransmission of GABA, the main inhibitory neurotransmitter in the central nervous system (CNS). In recent decades, the receptor has been extensively studied with the intention being to understand pathophysiological roles, structural mechanisms and develop drugs. The dysfunction of the receptor is linked to a broad variety of disorders, including anxiety, depression, alcohol addiction, memory and cancer. Despite extensive efforts, few compounds are known to target the receptor, and only the agonist baclofen is approved for clinical use. The receptor is a mandatory heterodimer of the GABA and GABA subunits, and each subunit is composed of an extracellular Venus Flytrap domain (VFT) and a transmembrane domain of seven α-helices (7TM domain). In this review, we briefly present the existing knowledge about the receptor structure, activation and compounds targeting the receptor, emphasizing the role of the receptor in previous and future drug design and discovery efforts.
Topics: Baclofen; Binding Sites; Drug Development; GABA-B Receptor Antagonists; Humans; Ligands; Models, Molecular; Protein Conformation, alpha-Helical; Receptors, GABA-B
PubMed: 32646032
DOI: 10.3390/molecules25133093 -
Neurology(R) Neuroimmunology &... May 2023Among the glutamic acid decarboxylase (GAD)-antibody-spectrum disorders, the most common phenotypic subset is the stiff-person syndrome (SPS), caused by impaired... (Review)
Review
Among the glutamic acid decarboxylase (GAD)-antibody-spectrum disorders, the most common phenotypic subset is the stiff-person syndrome (SPS), caused by impaired GABAergic inhibitory neurotransmission and autoimmunity characterized by very high titers of GAD antibodies and increased GAD-IgG intrathecal synthesis. If not properly treated or untreated because of delayed diagnosis, SPS progresses leading to disability; it is therefore fundamental to apply the best therapeutic schemes from the outset. This article is focused on the rationale of specific therapeutic strategies based on the SPS pathophysiology targeting both the impaired reciprocal GABAergic inhibition to symptomatically improve the main clinical manifestations of stiffness in the truncal and proximal limb muscles, gait dysfunction, and episodic painful muscle spasms and the autoimmunity to enhance improvement and slow down disease progression. A practical, step-by-step therapeutic approach is provided, highlighting the importance of combination therapies with the preferred gamma-aminobutyric acid-enhancing antispasmodic drugs, such as baclofen, tizanidine, benzodiazepines, and gabapentin, that provide the first-line symptomatic therapy, while detailing the application of current immunotherapies with intravenous immunoglobulin (IVIg) plasmapheresis, and rituximab. The pitfalls and concerns of long-term therapies in different age groups, including children, women planning pregnancy, and especially the elderly considering their comorbidities are emphasized, also highlighting the challenges in distinguishing the conditioning effects or expectations of chronically applied therapies from objective meaningful clinical benefits. Finally, the need for future targeted immunotherapeutic options based on disease immunopathogenesis and the biologic basis of autoimmune hyperexcitability are discussed, pointing out the unique challenges in the design of future controlled clinical trials especially in quantifying the extend and severity of stiffness, episodic or startle-triggered muscle spasms, task-specific phobias, and excitability.
Topics: Child; Humans; Female; Aged; Stiff-Person Syndrome; Autoantibodies; Autoimmunity; Baclofen; Spasm
PubMed: 37059468
DOI: 10.1212/NXI.0000000000200109 -
The Cochrane Database of Systematic... Aug 2017Baclofen shows potential for rapidly reducing symptoms of severe alcohol withdrawal syndrome (AWS) in people with alcoholism. Treatment with baclofen is easy to manage... (Review)
Review
BACKGROUND
Baclofen shows potential for rapidly reducing symptoms of severe alcohol withdrawal syndrome (AWS) in people with alcoholism. Treatment with baclofen is easy to manage and rarely produces euphoria or other pleasant effects, or craving for the drug. This is an updated version of the original Cochrane Review published in 2015, Issue 4.
OBJECTIVES
To assess the efficacy and safety of baclofen for people with AWS.
SEARCH METHODS
We updated our searches of the following databases to March 2017: the Cochrane Drugs and Alcohol Group Specialised Register, CENTRAL, PubMed, Embase, and CINAHL. We also searched registers of ongoing trials. We handsearched the references quoted in the identified trials, and sought information from researchers, pharmaceutical companies, and relevant trial authors about unpublished or uncompleted trials. We placed no restrictions on language.
SELECTION CRITERIA
We included all randomised controlled clinical trials (RCTs) evaluating baclofen versus placebo or any other treatment for people with AWS. We excluded uncontrolled, non-randomised, or quasi-randomised trials. We included both parallel group and cross-over studies.
DATA COLLECTION AND ANALYSIS
We used standard methodological procedures expected by Cochrane.
MAIN RESULTS
We included three RCTs with 141 randomised participants. We did not perform meta-analyses due to the different control interventions. For the comparison of baclofen and placebo (1 study, 31 participants), there was no significant difference in Clinical Institute Withdrawal Assessment of Alcohol Scale, Revised (CIWA-Ar) scores (very low quality evidence). For the comparison of baclofen and diazepam (1 study, 37 participants), there was no significant difference in CIWA-Ar scores (very low quality evidence), adverse events (risk difference (RD) 0.00, 95% confidence interval (CI) -0.10 to 0.10; very low quality evidence), dropouts (RD 0.00, 95% CI -0.10 to 0.10; very low quality evidence), and dropouts due to adverse events (RD 0.00, 95% CI -0.10 to 0.10; very low quality evidence). For the comparison of baclofen and chlordiazepoxide (1 study, 60 participants), there was no significant difference in CIWA-Ar scores (mean difference (MD) 1.00, 95% CI 0.70 to 1.30; very low quality evidence), global improvement (MD 0.10, 95% CI -0.03 to 0.23; very low quality evidence), adverse events (RD 2.50, 95% CI 0.88 to 7.10; very low quality of evidence), dropouts (RD 0.00, 95% CI -0.06 to 0.06; very low quality evidence), and dropouts due to adverse events (RD 0.00, 95% CI -0.06 to 0.06; very low quality evidence).
AUTHORS' CONCLUSIONS
No conclusions can be drawn about the efficacy and safety of baclofen for the management of alcohol withdrawal because we found insufficient and very low quality evidence.
Topics: Alcohol-Induced Disorders; Baclofen; Chlordiazepoxide; Diazepam; Ethanol; GABA Agonists; Humans; Randomized Controlled Trials as Topic; Substance Withdrawal Syndrome
PubMed: 28822350
DOI: 10.1002/14651858.CD008502.pub5 -
The Cochrane Database of Systematic... Jan 2023Alcohol use disorder (AUD) is one of the most widespread psychiatric disorders leading to detrimental consequences to people with this disorder and others. Worldwide,... (Review)
Review
BACKGROUND
Alcohol use disorder (AUD) is one of the most widespread psychiatric disorders leading to detrimental consequences to people with this disorder and others. Worldwide, the prevalence of heavy episodic drinking (30-day prevalence of at least one occasion of 60 g of pure alcohol intake among current drinkers) is estimated at 20% and the prevalence of AUD at 5% of the adult general population, with highest prevalence in Europe and North America. Therapeutic approaches, including pharmacotherapy, play an important role in treating people with AUD. This is an update of a Cochrane Review first published in 2018.
OBJECTIVES
To evaluate the benefits and harms of baclofen on achieving and maintaining abstinence or reducing alcohol consumption in people with AUD compared to placebo, no treatment or any other pharmacological relapse prevention treatment.
SEARCH METHODS
We used standard, extensive Cochrane search methods. The latest search was 22 November 2021.
SELECTION CRITERIA
Randomised controlled trials (RCTs) of at least four weeks' treatment duration and 12 weeks' overall study duration comparing baclofen for AUD treatment with placebo, no treatment or other treatments.
DATA COLLECTION AND ANALYSIS
We used standard Cochrane methods. Our primary outcomes were 1. relapse, 2. frequency of use, 3. amount of use, 4. adverse events, 5. dropouts from treatment and 6. dropouts from treatment due to adverse events. Our secondary outcomes were 7. craving, 8. anxiety, 9. depression and 10. frequency of most relevant adverse events.
MAIN RESULTS
We included 17 RCTs (1818 participants) with a diagnosis of alcohol dependence according to the Diagnostic and Statistical Manual of Mental Disorders, 4th edition or International Classification of Diseases 10th edition criteria. Mean age was 46.5 years and 70% were men. Ten studies compared baclofen to placebo or another medication; seven compared two baclofen doses to placebo or another medication. Globally, 15 studies compared baclofen to placebo, two baclofen to acamprosate and two baclofen to naltrexone. In 16 studies, participants received psychosocial treatments. We judged most studies at low risk of selection, performance, detection (subjective outcome), attrition and reporting bias. Ten studies detoxified participants before treatment; in seven studies, participants were still drinking at the beginning of treatment. Treatment duration was 12 weeks for 15 RCTs and longer in two studies. Baclofen daily dose was 30 mg to 300 mg: 10 RCTs used low doses (30 mg or less); eight RCTs medium doses (above 30 and 100 mg or less) and four RCTs high doses (above 100 mg). Compared to placebo, moderate-certainty evidence found that baclofen probably decreases the risk to relapse (risk ratio (RR) 0.87, 95% confidence interval (CI) 0.77 to 0.99; 12 studies, 1057 participants). This result was confirmed among detoxified participants but not among other subgroups of participants. High-certainty evidence found that baclofen increases the percentage of days abstinent (mean difference (MD) 9.07, 95% CI 3.30 to 14.85; 16 studies, 1273 participants). This result was confirmed among all subgroups of participants except non-detoxified or those who received medium doses. There was no difference between baclofen and placebo in the other primary outcomes: heavy drinking days (standardised mean difference (SMD) -0.18, 95% CI -0.48 to 0.11; 13 studies, 840 participants; moderate-certainty evidence); number of drinks per drinking days (MD -0.45, 95% CI -1.20 to 0.30; 9 studies, 392 participants; moderate-certainty evidence); number of participants with at least one adverse event (RR 1.05, 95% CI 0.99 to 1.11; 10 studies, 738 participants; high-certainty evidence); dropouts (RR 0.88, 95% CI 0.74 to 1.03; 17 studies, 1563 participants; high-certainty evidence); dropouts due to adverse events (RR 1.39, 95% CI 0.89 to 2.18; 16 studies, 1499 participants; high-certainty evidence). These results were confirmed by subgroup analyses except than for the dropouts that resulted lower among participants who received high doses of baclofen and studies longer than 12 weeks. Compared to placebo, there was no difference in craving (SMD -0.16, 95% CI -0.37 to 0.04; 17 studies, 1275 participants), anxiety (MD -0.01, 95% CI -0.14 to 0.11; 15 studies, 1123 participants) and depression (SMD 0.07, 95% CI -0.12 to 0.27; 11 studies, 1029 participants). Concerning the specific adverse events, baclofen increases fatigue, dizziness, somnolence/sedation, dry mouth, paraesthesia and muscle spasms/rigidity. There was no difference in the other adverse events. Compared to acamprosate, one study (60 participants) found no differences in any outcomes but the evidence was very uncertain: relapse (RR 1.25, 95% CI 0.71 to 2.20; very low-certainty evidence); number of participants with at least one adverse event (RR 0.63, 95% CI 0.23 to 1.69; very low-certainty evidence); dropouts (RR 0.56, 95% CI 0.21 to 1.46; very low-certainty evidence); dropouts due to adverse events (RR 0.33, 95% CI 0.01 to 7.87; very low-certainty evidence) and craving (MD 5.80, 95% CI -11.84 to 23.44); and all the adverse events evaluated. Compared to naltrexone, baclofen may increase the risk of relapse (RR 2.50, 95% CI 1.12 to 5.56; 1 study, 60 participants; very low-certainty evidence) and decrease the number of participants with at least one adverse event (RR 0.35, 95% CI 0.15 to 0.80; 2 studies, 80 participants; very low-certainty evidence) but the evidence is very uncertain. One study (60 participants) found no difference between baclofen and naltrexone in the dropouts at the end of treatment (RR 1.00, 95% CI 0.32 to 3.10; very low-certainty evidence), craving (MD 2.08, 95% CI -3.71 to 7.87), and all the adverse events evaluated.
AUTHORS' CONCLUSIONS
Baclofen likely reduces the risk of relapse to any drinking and increases the percentage of abstinent days, mainly among detoxified participants. It does not increase the number of participants with at least one adverse event, those who dropout for any reason or due to adverse events. It probably does not reduce number of heavy drinking days and the number of drinks per drinking days. Current evidence suggests that baclofen may help people with AUD in maintaining abstinence. The results of comparisons of baclofen with acamprosate and naltrexone were mainly based on only one study.
Topics: Adult; Female; Humans; Male; Middle Aged; Acamprosate; Alcohol Drinking; Alcoholism; Baclofen; Chronic Disease; Naltrexone
PubMed: 36637087
DOI: 10.1002/14651858.CD012557.pub3 -
Tidsskrift For Den Norske Laegeforening... Sep 2023Spasticity is a frequent complication of diseases of and injuries to the central nervous system. Early treatment prevents further loss of function and spasticity-related... (Review)
Review
BACKGROUND
Spasticity is a frequent complication of diseases of and injuries to the central nervous system. Early treatment prevents further loss of function and spasticity-related complications. Basic spasticity treatment begins in the primary healthcare service and includes physiotherapy, occupational therapy and oral spasmolytics, while treatment with botulinum toxin and baclofen pump is carried out by the specialist healthcare services. The objective of the study was to obtain an overview of the availability and organisation of these specialised forms of spasticity treatment in Norway.
MATERIAL AND METHOD
We conducted a survey in which a digital questionnaire was sent to hospitals that offer spasticity treatment.
RESULTS
A total of 30 of 47 hospital departments/outpatient clinics (hereafter referred to as 'hospital units') distributed across all Norwegian health regions responded to the questionnaire. Spasticity treatment with botulinum toxin and baclofen pump was available in all of the health regions. Median time from first referral was 10 weeks (interquartile range 7 weeks). A total of 14 of 30 hospital units expressed a need for more treatment days to cover the local demand. Of the 30 hospital units, 23 had interdisciplinary teams with doctors, physiotherapists, occupational therapists and/or nurses. For treatment with botulinum toxin, ultrasound was used as guidance in 22 of 26 hospital units, EMG was used in 15 units and electrical muscle stimulation was used in 11 units.
INTERPRETATION
The study suggests that there may be a need for improvements to specialised spasticity treatment in Norway to ensure good patient care pathways, interdisciplinary assessments, and safe and efficient performance of the practical interventions.
Topics: Humans; Baclofen; Botulinum Toxins; Hospitals; Muscle Spasticity; Norway
PubMed: 37668130
DOI: 10.4045/tidsskr.22.0774 -
Mayo Clinic Proceedings May 2023To quantify the risk of encephalopathy associated with oral baclofen compared with other muscle relaxants-tizanidine or cyclobenzaprine.
OBJECTIVE
To quantify the risk of encephalopathy associated with oral baclofen compared with other muscle relaxants-tizanidine or cyclobenzaprine.
PATIENTS AND METHODS
We conducted a new-user, active-comparator study of 2 pairwise cohorts using tertiary health system data from Geisinger Health in Pennsylvania (January 1, 2005, through December 31, 2018). Adults (aged ≥18 years) newly treated with baclofen or tizanidine were included in cohort 1. Adults newly treated with baclofen or cyclobenzaprine were included in cohort 2. Propensity score-based inverse probability of treatment weighting (IPTW) was used to balance the respective cohorts on 45 patient characteristics. Fine-Gray competing risk regression was used to estimate the risk of encephalopathy.
RESULTS
Cohort 1 included 16,192 new baclofen users and 9782 new tizanidine users. The 30-day risk of encephalopathy was higher in patients treated with baclofen vs tizanidine (IPTW incidence rate, 64.7 vs 28.3 per 1000 person-years) with an IPTW subdistribution hazard ratio (SHR) of 2.29 (95% CI, 1.43 to 3.67). This risk persisted through 1 year (SHR, 1.32 [95% CI, 1.07 to 1.64]). Similarly in cohort 2, baclofen vs cyclobenzaprine was associated with a greater risk of encephalopathy at 30 days (SHR, 2.35 [95% CI, 1.59 to 3.48]) that persisted through the first year of treatment (SHR, 1.94 [95% CI, 1.56 to 2.40]).
CONCLUSION
The risk of encephalopathy was greater with baclofen vs tizanidine or cyclobenzaprine use. The elevated risk was apparent as early as 30 days and persisted through the first year of treatment. Our findings from routine care settings may inform shared treatment decisions between patients and prescribers.
Topics: Adult; Humans; Adolescent; Baclofen; Muscle Relaxants, Central; Muscle Spasticity; Cohort Studies; Brain Diseases
PubMed: 37028980
DOI: 10.1016/j.mayocp.2022.11.004 -
Journal of Rehabilitation Medicine Mar 2017Oral baclofen has long been a mainstay in the management of spasticity. This review looks at the clinical evidence for the efficacy and safety of oral baclofen in... (Review)
Review
Oral baclofen has long been a mainstay in the management of spasticity. This review looks at the clinical evidence for the efficacy and safety of oral baclofen in patients with spasticity of any origin or severity, to determine whether there is a rationale for the use of intrathecal baclofen. Results suggest that oral baclofen may be effective in many patients with spasticity, regardless of the underlying disease or severity, and that it is at least comparable with other antispasmodic agents. However, adverse effects, such as muscle weakness, nausea, somnolence and paraesthesia, are common with oral baclofen, affecting between 25% and 75% of patients, and limiting its usefulness. Intrathecal baclofen may be an effective alternative as the drug is delivered directly into the cerebrospinal fluid, thus bypassing the blood-brain barrier and thereby optimizing the efficacy of baclofen while minimizing drug-related side-effects. Intrathecal baclofen is a viable option in patients who experience intolerable side-effects or who fail to respond to the maximum recommended dose of oral baclofen.
Topics: Administration, Oral; Adult; Baclofen; Disorders of Excessive Somnolence; Dose-Response Relationship, Drug; Female; Humans; Injections, Spinal; Male; Muscle Relaxants, Central; Muscle Spasticity; Muscle Weakness; Nausea; Parasympatholytics
PubMed: 28233010
DOI: 10.2340/16501977-2211 -
Biomolecules Feb 2023This study aims to explore the role of GABA receptors in the development of deprivation myopia (DM), lens-induced myopia (LIM) and lens-induced hyperopia (LIH). Chicks...
This study aims to explore the role of GABA receptors in the development of deprivation myopia (DM), lens-induced myopia (LIM) and lens-induced hyperopia (LIH). Chicks were intravitreally injected with 25 µg baclofen (GABAR agonist) in one eye and saline into the fellow eye. Choroidal thickness (ChT) was measured via OCT before and 2, 4, 6, 8, 24 h after injection. ChT decreased strongly at 6 and 8 h after baclofen injection and returned back to baseline level after 24 h. Moreover, chicks were monocularly treated with translucent diffusers, -7D or +7D lenses and randomly assigned to baclofen or saline treatment. DM chicks were injected daily into both eyes, while LIM and LIH chicks were monocularly injected into the lens-wearing eyes, for 4 days. Refractive error, axial length and ChT were measured before and after treatment. Dopamine and its metabolites were analyzed via HPLC. Baclofen significantly reduced the myopic shift and eye growth in DM and LIM eyes. However, it did not change ChT compared to respective saline-injected eyes. On the other hand, baclofen inhibited the hyperopic shift and choroidal thickening in LIH eyes. All the baclofen-injected eyes showed significantly lower vitreal DOPAC content. Since GABA is an inhibitory ubiquitous neurotransmitter, interfering with its signaling affects spatial retinal processing and therefore refractive error development with both diffusers and lenses.
Topics: Animals; Baclofen; Chickens; Choroid; Hyperopia; Myopia; Refractive Errors
PubMed: 36979369
DOI: 10.3390/biom13030434 -
The Journal of Physiology Nov 2018Short-latency afferent inhibition (SAI) is modulated by GABA receptor activity, whereas the pharmacological origin of long-latency afferent inhibition remains unknown....
KEY POINTS
Short-latency afferent inhibition (SAI) is modulated by GABA receptor activity, whereas the pharmacological origin of long-latency afferent inhibition remains unknown. This is the first study to report that long-latency afferent inhibition (LAI) is reduced by the GABA positive allosteric modulator lorazepam, and that both SAI and LAI are not modulated by the GABA agonist baclofen. These findings advance our understanding of the neural mechanisms underlying afferent inhibition.
ABSTRACT
The afferent volley evoked by peripheral nerve stimulation has an inhibitory influence on transcranial magnetic stimulation induced motor evoked potentials. This phenomenon, known as afferent inhibition, occurs in two phases: short-latency afferent inhibition (SAI) and long-latency afferent inhibition (LAI). SAI exerts its inhibitory influence via cholinergic and GABAergic activity. The neurotransmitter receptors that mediate LAI remain unclear. The present study aimed to determine whether LAI is contributed by GABA and/or GABA receptor activity. In a double-blinded, placebo-controlled study, 2.5 mg of lorazepam (GABA agonist), 20 mg of baclofen (GABA agonist) and placebo were administered to 14 males (mean age 22.7 ± 1.9 years) in three separate sessions. SAI and LAI, evoked by stimulation of the median nerve and recorded from the first dorsal interosseous muscle, were quantified before and at the peak plasma concentration following drug ingestion. Results indicate that lorazepam reduced LAI by ∼40% and, in support of previous work, reduced SAI by ∼19%. However, neither SAI, nor LAI were altered by baclofen. In a follow-up double-blinded, placebo-controlled study, 10 returning participants received placebo or 40 mg of baclofen (double the dosage used in Experiment 1). The results obtained indicate that SAI and LAI were unchanged by baclofen. This is the first study to show that LAI is modulated by GABA receptor activity, similar to SAI, and that afferent inhibition does not appear to be a GABA mediated process.
Topics: Baclofen; GABA Agonists; Humans; Lorazepam; Male; Median Nerve; Neural Inhibition; Neurons, Afferent; Reaction Time; Young Adult
PubMed: 30192388
DOI: 10.1113/JP276710 -
European Journal of Clinical... Mar 2018Gamma-hydroxybutyrate (GHB) withdrawal is a life-threatening condition that does not always respond to standard treatment with benzodiazepines. Baclofen has potential... (Review)
Review
PURPOSE
Gamma-hydroxybutyrate (GHB) withdrawal is a life-threatening condition that does not always respond to standard treatment with benzodiazepines. Baclofen has potential utility as a pharmacological adjunct and anecdotal reports suggest that it is being used by drug users to self-manage GHB withdrawal symptoms. Here, we investigate current patterns of use and the online availably of baclofen.
METHODS
Data triangulation techniques were applied to published scientific literature and publicly accessible Internet resources (grey literature) to assess the use of baclofen in GHB withdrawal. An Internet snapshot survey was performed to identify the availability of baclofen for online purchase and the compliance of retailers with the UK regulations. Data were collected according to pre-defined criteria.
RESULTS
A total of 37 cases of baclofen use in GHB withdrawal were identified in the scientific literature, as well as 51 relevant discussion threads across eight Internet forums in the grey literature. Baclofen was available to purchase from 38 online pharmacies, of which only one conformed to the UK regulations.
CONCLUSIONS
There is limited published evidence on the use of baclofen in GHB withdrawal, but both scientific and grey literature suggests clinical utility. Online pharmacies are readily offering prescription-only-medication without prescription and due to inadequate regulation, pose a danger to the public.
Topics: Animals; Baclofen; Biomedical Research; Drug Trafficking; GABA-B Receptor Agonists; Humans; Internet; Pharmaceutical Services, Online; Practice Patterns, Physicians'; Prescription Drugs; Psychotropic Drugs; Social Media; Sodium Oxybate; Substance Withdrawal Syndrome; United Kingdom
PubMed: 29198063
DOI: 10.1007/s00228-017-2387-z