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Aims: Dopamine replacement therapy is the backbone of Parkinson's disease (PD) treatment. However, long-term levodopa (L-DOPA) administration can lead to the severely disabling motor complication L-DOPA-induced dyskinesia (LID), for which standard, effective therapy is currently lacking. This study was conducted to characterize the distinct neural electrophysiological patterns involved in the progression of PD and to examine the efficacy of tetrabenazine, a vesicular monoamine transporter-2 inhibitor, in alleviating dyskinesia and its underlying electrophysiological mechanism., Methods: Electrophysiological analysis was performed to obtain power spectrum density and functional connectivity information from local field potential (LFP) data recorded from the primary motor cortex (M1) and dorsolateral striatum (DLS) during different pathological states in PD model rats. Behavioral tests and abnormal involuntary movements (AIMs) scoring were conducted to confirm PD model establishment and assess LID severity., Results: Increased beta oscillations and abnormally strengthened beta causality in the M1 → DLS direction and exaggerated beta-band M1-DLS functional connectivity were observed in the PD state. L-DOPA administration suppressed beta activity and augmented gamma power in the M1 and DLS, with increased gamma causality in the M1 → DLS direction and beta causality in the DLS → M1 direction, as well as elevated gamma-band M1-DLS functional connectivity. Tetrabenazine strongly ameliorated dyskinetic manifestations. It suppressed gamma power in the M1 and DLS, reduced gamma causality and increased beta causality in the M1 → DLS direction, reduced beta causality in the DLS → M1 direction, and reduced gamma-band M1-DLS functional connectivity., Conclusion: Tetrabenazine abrogated aberrant gamma activity to improve LID symptoms, which provides compelling evidence for its future clinical application in LID therapy., (© 2025 The Author(s). CNS Neuroscience & Therapeutics published by John Wiley & Sons Ltd.)

Introduction: Chorea is a motor manifestation of Huntington's disease (HD), which can lead to decreased functional independence and falls. Even though multiple classes of medications have been used to treat this symptom, only the vesicular monoamine transporter 2 (VMAT2) inhibitors tetrabenazine, deutetrabenazine, and valbenazine have been approved by the FDA for this indication., Areas Covered: This article reviews the pharmacological properties, clinical efficacy, safety, and tolerability of valbenazine in the treatment of chorea in HD. Key considerations in the concomitant use of VMAT2 inhibitors with other medications are discussed, particularly considerations specific to valbenazine use plus medications often used to treat neuropsychiatric symptoms in HD., Expert Opinion: Valbenazine effectively addresses chorea. Its selectivity avoids VMAT1-related side effects and tardive dyskinesia and may result in less off-target side effects such as parkinsonism, behavioral changes, and akathisia. The cost of this medication could be a barrier to access, even for those with insurance, due to high co-pay fees. Head-to-head clinical trials are needed to compare valbenazine's efficacy with the other approved drugs for chorea in HD.

Introduction: Tardive dyskinesia (TD) and Huntington's disease (HD)-associated chorea are persistent and disabling hyperkinetic disorders that can be treated with vesicular monoamine transporter type 2 (VMAT2) inhibitors, including the recently approved once-daily (QD) formulation of deutetrabenazine (DTBZ ER). While its efficacy and safety profile have not been directly investigated, currently available data confirms bioequivalence and similar bioavailability to the twice-daily formulation (DTBZ BID)., Areas Covered: The authors briefly review the pivotal trials establishing efficacy of DTBZ for TD and HD-associated chorea, the pharmacokinetic data for bioequivalence between QD and BID dosing of DTBZ, as well as dose proportionality evidence, titration recommendations, and safety profile for DTBZ ER., Expert Opinion: Long-term data show that DTBZ is efficacious and well tolerated for the treatment of TD and HD-associated chorea. DTBZ ER likely demonstrates therapeutic equivalence with no new safety signals. Due to the lack of comparative clinical trial data, no evidence-based recommendation about choice of VMAT2 inhibitor or switching between VMAT2 inhibitors can be made about best practice. Ultimately, QD dosing may offer the chance of improved medication adherence, an important consideration in patients with complex treatment regimens and/or patients with cognitive decline.

Introduction: GNAO1 encephalopathy is characterized by severe hypotonia, psychomotor retardation, epilepsy, and movement disorders. Genetic variations in GNAO1 have been linked to neurological symptoms including movement disorders like dystonia. The correlation between the E246K mutation in the Gα subunit and aberrant signal transduction of G proteins has been established but no data are reported regarding the efficacy of medical treatment with tetrabenazine., Methods: Molecular modeling studies were performed to elucidate the molecular mechanisms underlying this mutation. We developed drug efficacy models using molecular dynamic simulations that replicated the behavior of wild-type and mutated proteins in the presence or absence of ligands., Results and Discussion: We demonstrated that the absence of the mutation leads to normal signal transduction upon receptor activation by the endogenous ligand, but not in the presence of tetrabenazine. In contrast, the presence of the mutation resulted in abnormal signal transduction in the presence of the endogenous ligand, which was corrected by the drug tetrabenazine. Tetrabenazine was identified as a promising therapeutic option for pediatric patients suffering from encephalopathy due to an E246K mutation in the GNAO1 gene validated through molecular dynamics. This is a potential first example of the use of this technique in a rare neurological pediatric disease., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Background: Tardive Dyskinesia (TD) is a neurological disorder characterized by involuntary movements, often caused by dopamine receptor antagonists. Vesicular Monoamine Transporter 2 (VMAT2) inhibitors, such as valbenazine and deutetrabenazine, have emerged as promising therapies for TD and several clinical trials have shown their efficacy. This study aims to compare the efficacy and safety profile of VMAT2 inhibitors, focusing on a recent trial conducted in the Asian population., Methods: We reviewed the PubMed, Cochrane Library, Embase database, and clinicaltrials.gov between January 2017 and October 2023, using the keywords "tardive dyskinesia" AND ("valbenazine" [all fields] OR " deutetrabenazine " [all fields]) AND "clinical trial". The reviewed articles were studied for efficacy and side effects., Results: An initial search yielded 230 articles, of which 104 were duplicates. Following the title and abstract screening, 25 additional articles were excluded. A full-text review resulted in the exclusion of 96 more articles. Ultimately, four double-blind clinical trials met the inclusion criteria. The deutetrabenazine studies demonstrated significant improvements in Abnormal Involuntary Movement Scale (AIMS) scores compared to placebo, with no difference in adverse events. The valbenazine studies showed favorable results in reducing TD symptoms and were well-tolerated., Discussion: The studies reviewed in this analysis underscore the potential of deutetrabenazine and valbenazine as valuable treatment options for TD in diverse populations. Both medications demonstrated significant improvements in AIMS scores, suggesting their effectiveness in managing TD symptoms. Additionally, they exhibited favorable safety profiles, with low rates of serious adverse events and no significant increase in QT prolongation, parkinsonism, suicidal ideation, or mortality., Conclusion: The studies reviewed highlight the promising efficacy and tolerability of deutetrabenazine and valbenazine as treatments for Tardive Dyskinesia, providing new hope for individuals affected by this challenging condition., Competing Interests: Dr. Khashayar Dashtipour’s conflict of interest: Amneal, Teva, Neurocrine, Abbvie, Supernus, Ipsen, Acadia, Acorda, Sunovion. The authors have no competing interests to declare., (Copyright: © 2024 The Author(s).)

Rationale: Dopamine antagonists induce dopamine receptor supersensitivity. This may manifest in late-appearing movement disorders (tardive dyskinesia (TD). VMAT-2 inhibitors reduce dopaminergic transmission but have limited activity at postsynaptic receptors and so may have antipsychotic activity with lower risk of tardive dyskinesia., Methods: We conducted a systematic database search from inception to September 2022 for articles describing the use of VMAT-2 inhibitors in psychosis. Inclusion criteria were as follows: Population: adults diagnosed with psychosis or schizophrenia; Intervention: treatment with tetrabenazine, deutetrabenazine or valbenazine; Comparison: comparison with placebo or/and antipsychotic drug; Outcomes: with efficacy outcomes (e.g. Brief Psychiatric Rating Scale (BPRS) change or clinician assessment) and adverse effects ratings (e.g. rating scale or clinician assessment or dropouts); and Studies: in randomised controlled trials and non-randomised studies., Results: We identified 4892 records relating to VMAT-2 inhibitor use of which 5 (173 participants) met our a priori meta-analysis inclusion criteria. VMAT-2 inhibitors were more effective than placebo for the outcome 'slight improvement' (risk ratio (RR) = 1.77 (95% CI 1.03, 3.04)) but not for 'moderate improvement' (RR 2.81 (95% CI 0.27, 29.17). VMAT-2 inhibitors were as effective as active comparators on both measures for-'slight improvement' (RR 1.05 (95% CI 0.6, 1.81)) and 'moderate improvement' (RR 1.11 (95% CI 0.51, 2.42). Antipsychotic efficacy was also suggested by a narrative review of 37 studies excluded from the meta-analysis., Conclusions: VMAT-2 inhibitors may have antipsychotic activity and may offer promise for treatment of psychosis with the potential for a reduced risk of TD., (© 2023. The Author(s).)

Purpose: One-capsule, once-daily valbenazine is approved for tardive dyskinesia and under evaluation for chorea associated with Huntington's disease, conditions in which patients often experience dysphagia. In vitro studies were conducted to assess the suitability of crushing the contents of valbenazine capsules (40 and 80 mg) for mixing with soft foods or liquids or administration via a gastrostomy tube (G-tube)., Methods: In study 1, the dissolution of whole valbenazine capsules and crushed capsule contents were measured serially for 1 hour. In study 2, valbenazine recovery was evaluated after crushed contents were mixed with soft foods, buffer solutions (pH range, 1.2-6.8), and fed-state simulated gastric fluid. In study 3, valbenazine recovery was evaluated after crushed contents were dispersed in water and delivered via a G-tube. In studies 2 and 3, acceptable valbenazine recovery was 90% to 110%., Findings: Study 1 indicated rapid and complete drug release for whole valbenazine capsules and crushed capsule contents, with similar release at 10 minutes (whole, 94%-99%; crushed, 98%-100%) and 60 minutes (whole, 101%-103%; crushed, 101%-102%). Study 2 found acceptable valbenazine recovery within 2 hours of adding crushed capsule contents to tested foods, buffers, or fed-state simulated gastric fluid (recovery, 92%-102%). Study 3 found acceptable valbenazine recovery when crushed contents were added to cold or hot water and delivered via G-tube, with a water cup rinse to capture residual contents (recovery, 91%-97%)., Implications: These studies indicate the potential viability of valbenazine formulation(s) that can be added to soft foods or liquids or delivered via G-tube. Such formulations will be important for individuals who require treatment with a vesicular monoamine transporter 2 inhibitor but cannot swallow whole pills., Competing Interests: Declaration of Competing Interest The three studies included in this report were supported by Neurocrine Biosciences, Inc. MS has received the following: research grants within past 3 years from International Society for Bipolar Disorders (ISBD), National Institutes of Health (NIH), Centers for Disease Control and Prevention (CDC), Patient-Centered Outcomes Research Institute (PCORI), Merck, Otsuka, Alkermes; consultant fees in the past 1 year from Alkermes, Otsuka, Janssen, Lundbeck, Teva, Neurelis; royalties in the past 1 year from Springer Press, Johns Hopkins University Press, Oxford Press, UpToDate; and compensation in the past 1 year for CME preparation/participation in CME activities: American Physician's Institute (CMEtoGo), Psychopharmacology Institute, American Epilepsy Society, Clinical Care Options, American Academy of Child and Adolescent Psychiatry, Neurocrine. AP has received consulting fees from Neurocrine Biosciences, Inc. All remaining authors are full-time employees of Neurocrine Biosciences, Inc., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: The NKX2-1-related disorders (NKX2-1-RD) is a rare disorder characterized by choreiform movements along with respiratory and endocrine abnormalities. The European Reference Network of Rare Neurological Disorders funded by the European Commission conducted a systematic review to assess drug treatment of chorea in NKX2-1-RD, aiming to provide clinical recommendations for its management., Methods: A systematic pairwise review using various databases, including MEDLINE, Embase, Cochrane, CINAHL, and PsycInfo, was conducted. The review included patients diagnosed with chorea and NKX2-1-RD genetic diagnosis, drug therapy as intervention, no comparator, and outcomes of chorea improvement and adverse events. The methodological quality of the studies was assessed, and the study protocol was registered in PROSPERO., Results: Of the 1417 studies examined, 28 studies met the selection criteria, consisting of 68 patients. The studies reported 22 different treatments for chorea, including carbidopa/levodopa, tetrabenazine, clonazepam, methylphenidate, carbamazepine, topiramate, trihexyphenidyl, haloperidol, propranolol, risperidone, and valproate. No clinical improvements were observed with carbidopa/levodopa, tetrabenazine, or clonazepam, and various adverse effects were reported. However, most patients treated with methylphenidate experienced improvements in chorea and reported only a few negative effects. The quality of evidence was determined to be low., Conclusions: The management of chorea in individuals with NKX2-1-RD presents significant heterogeneity and lack of clarity. While the available evidence suggests that methylphenidate may be effective in improving chorea symptoms, the findings should be interpreted with caution due to the limitations of the studies reviewed. Nonetheless, more rigorous and comprehensive studies are necessary to provide sufficient evidence for clinical recommendations., (© 2023 The Authors. European Journal of Neurology published by John Wiley & Sons Ltd on behalf of European Academy of Neurology.)

Objectives: We aimed to review our "real-world" experience with the vesicular monoamine transporter 2 (VMAT2) inhibitors tetrabenazine, deutetrabenazine, and valbenazine for treatment of Tourette syndrome, focusing on therapeutic benefits, side effect profile, and accessibility for the off-label use of these drugs., Methods: We performed a retrospective chart review, supplemented with a telephone survey, of all our patients treated for their tics with VMAT2 inhibitors over a period of 4 years from January 2017 until January 2021., Results: We identified 164 patients treated with the various VMAT2 inhibitors (tetrabenazine, n = 135; deutetrabenazine, n = 71; valbenazine, n = 20). Data on the mean treatment duration and daily dosages were collected. The response to VMAT2 inhibitors was assessed by a Likert scale by comparing the symptom severity before initiation and while on treatment. Side effects were mild and mostly consisted of depression as the major side effect but there was no suicidality reported., Conclusion: VMAT2 inhibitors are effective and safe in the treatment of tics associated with Tourette syndrome but are not readily accessible by patients in the United States, partly because of lack of approval by the Food and Drug Administration., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany.)

Tardive dyskinesia (TD) is a persistent involuntary complex movement disorder that is known to occur with long-term antipsychotic treatment. Despite being a well-recognized complication of this treatment, its symptoms are often masked by the antipsychotic agents, only to become apparent upon reducing or terminating the treatment. In an effort to advance our understanding of TD pathophysiology and to identify potential therapies, the current study aimed to establish an animal model of TD by administering haloperidol to rats and to evaluate the efficacy of fluvoxamine, a selective serotonin reuptake inhibitor (SSRI), in ameliorating TD symptoms. The study compared the behavioral and biochemical parameters of rats that were treated with either fluvoxamine, tetrabenazine, haloperidol, or saline (control group). The biochemical parameters of interest included the brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), superoxide dismutase (SOD), and malondialdehyde (MDA). To achieve the study objectives, 32 male Wistar Albino rats were assigned to four different groups. The control group received physiological saline for six weeks. The haloperidol group received 1 mg/kg/ip haloperidol for the first three weeks, followed by two weeks of saline. The haloperidol+fluvoxamine group received 1 mg/kg/ip haloperidol for the first three weeks, followed by 30 mg/kg/ip fluvoxamine. The haloperidol+tetrabenazine group was administered 1 mg/kg/ip haloperidol for the first three weeks, followed by 5 mg/kg/ip tetrabenazine. Behavioral assessments of the rats were performed by measuring vacuous chewing movements. Subsequently, samples were collected from the hippocampus, striatum, and frontal lobe tissues of the rats, and BDNF, NGF, SOD, and MDA levels were measured. The results of the study demonstrated significant differences between the groups with respect to behavioral observations. Furthermore, SOD levels in the hippocampus, as well as BDNF, NGF, and SOD levels in the striatum of the haloperidol+fluvoxamine group were significantly higher than those observed in the haloperidol group. Conversely, MDA levels in the hippocampus were significantly lower in the haloperidol+fluvoxamine group than in the haloperidol group. These findings provide evidence of the beneficial effects of fluvoxamine, acting as a sigma-1 agonist, in treating TD symptoms induced experimentally. The observed benefits were supported by the biochemical investigations performed on brain tissue samples. Therefore, fluvoxamine may be considered as a potential alternative treatment for TD in clinical practice, although further research is needed to corroborate these findings., Competing Interests: Declaration of Competing Interest Authors report no conflicts of interest., (Copyright © 2023. Published by Elsevier Inc.)

Background: Huntington's disease is a rare neurodegenerative illness of the central nervous system that is inherited in an autosomal dominant pattern. Mutant huntingtin protein is produced as a result of enlargement of CAG repeat in the N-terminal of the polyglutamine tract., Aim of the Study: Herein, we aim to investigate the mutations and their effects on the HTT gene and its genetic variants. Additionally, the protein-protein interaction of HTT with other proteins and receptor-ligand interaction with the three-dimensional structure of huntingtin protein were identified., Methods: A comprehensive analysis of the HTT interactome and protein-ligand interaction has been carried out to provide a global picture of structure-function analysis of huntingtin protein. Mutations were analyzed and mutation verification tools were used to check the effect of mutation on protein function., Results: The results showed, mutations in a single gene are not only responsible for causing a particular disease but may also cause other hereditary disorders as well. Moreover, the modification at the nucleotide level also cause the change in the specific amino acid which may disrupt the function of HTT and its interacting proteins contributing in disease pathogenesis. Furthermore, the interaction between MECP2 and BDNF lowers the rate of transcriptional activity. Molecular docking further confirmed the strong interaction between MECP2 and BDNF with highest affinity. Amino acid residues of the HTT protein, involved in the interaction with tetrabenazine were N912, Y890, G2385, and V2320. These findings proved, tetrabenazine as one of the potential therapeutic agent for treatment of Huntington's disease., Conclusion: These results give further insights into the genetics of Huntington's disease for a better understanding of disease models which will be beneficial for the future therapeutic studies., (© 2022. The Author(s), under exclusive licence to Royal Academy of Medicine in Ireland.)

Tardive dyskinesia (TD) is a delayed, often irreversible iatrogenic movement disorder caused by long-term use of that dopamine receptors blocking drugs. Prevention of TD is paramount, and clinicians should follow best practice recommendations for prescribing antipsychotics, as well as reduction the using of dopamine receptor blocking drugs for non-psychiatric prescriptions. Replacement of antipsychotics with lower affinity for D2 receptors drugs, addition of VMAT2 (tetrabenazine), botulinum therapy, amantadine may be effective. In detection and incurable cases, the possibility of neuromodulation of brain structures should be considered. Most methods for testing TD currently have an insufficient level of evidence, although they include recommendations from professional communities. There is a great need for new clinical trials.

Purpose/aim: Diabetic chorea is a rare movement disorder associated with diabetes mellitus. We report the case of a patient that benefited from pimozide and died of pancreatic cancer., Case Report: A 70-year-old woman presented with pollakiuria and involuntary movements of left limbs since three months. Laboratory tests revealed high serum levels of glycemia and glycated haemoglobin. She was admitted to internal medicine department and discharged one week later: insulin was administered with normalization of blood glucose levels and the involuntary movements gradually disappeared. Three weeks later she was admitted to neurological department due to the recurrence of the involuntary movements. Glycemia and other routine laboratory tests were normal. Neurological examination showed choreic movements involving left limbs. MRI showed a hyperintensity on T1- and T2-weighted sequences of right putamen and caudate nucleus head. Haloperidol was administered without improvement, it was successively substituted with tetrabenazine and the patient was discharged with an unvaried clinical picture. Two months later tetrabenazine was discontinued because of inefficacy and pimozide was started. The choreic movements considerably diminished after few days. Four months later, a pancreatic cancer was diagnosed and the patient died in the same month., Conclusion: Clinical and radiological features were suggestive of diabetic chorea. Our patient benefited exclusively from pimozide, it could be reasonable to use pimozide in resistant form and also propose it as first choice treatment. Another important element is the diagnosis of pancreatic cancer some months after chorea onset: a causal link could exist.

Tardive dyskinesia is recognized as buccolingual dyskinesia, but also includes various involuntary movements, such as chorea, dystonia, myoclonus, and tremor. Tardive dyskinesia can be treated depending on the type of movement disorder present. Antipsychotics causing tardive dyskinesia should be reduced in dosage or should be discontinued. However, the treatment of schizophrenia is important, and neurologists must treat tardive dyskinesia in collaboration with psychiatrists taking care of patients with tardive dystonia. Various treatments, such as VMAT-2 inhibitors or tetrabenazine, reserpine, dopamine receptor antagonists, botulinum toxin therapy, anticholinergic agents, or deep brain stimulation, are trialed, depending on the type of movement disorder and the degree of severity of the disorder.

Introduction: Deutetrabenazine is approved by the US Food and Drug Administration to treat tardive dyskinesia (TD) based on 2 pivotal, 12-week, placebo-controlled studies (ARM-TD and AIM-TD) evaluating safety and efficacy in patients with baseline total motor Abnormal Involuntary Movement Scale (AIMS) score ≥6. This analysis estimated the minimal clinically important change (MCIC) in total motor AIMS score in TD patients treated with deutetrabenazine., Methods: The pooled analysis population included all patients in ARM-TD and AIM-TD who received study drug and had ≥1 postbaseline AIMS assessment. MCIC analyses were performed using Patient Global Impression of Change (PGIC) and Clinical Global Impression of Change (CGIC) as anchors. MCIC was defined as the mean change from baseline in total motor AIMS score in patients treated with deutetrabenazine who were rated minimally improved on PGIC or CGIC at Week 12., Results: This analysis included 295 patients (deutetrabenazine, n = 197; placebo, n = 98). At Week 12, the MCIC in deutetrabenazine-treated patients was -2.4 based on the PGIC and -2.1 based on the CGIC. Mean change from baseline in total motor AIMS score for placebo-treated patients rated minimally improved was -1.4 based on the PGIC and -1.5 based on the CGIC. The proportion of deutetrabenazine-treated patients who achieved improvement in total motor AIMS score by ≥2 and ≥3 points was 66% and 55%, respectively., Conclusion: Using anchor-based methodology, the MCIC on the AIMS for deutetrabenazine in patients with TD was approximately -2, suggesting that a reduction in total motor AIMS score of ∼2 is associated with clinically meaningful improvement in TD symptoms., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Huntington's disease (HD) is a rare, incurable, inheritedneurodegenerative disorder manifested by chorea, hyperkinetic, and hypokinetic movements. The FDA has approved only two drugs, viz. tetrabenazine, and deutetrabenazine, to manage the chorea associated with HD. However, several other drugs are used as an off-label to manage chorea and other symptoms such as depression, anxiety, muscle tremors, and cognitive dysfunction associated with HD. So far, there is no disease-modifying treatment available. Drug repurposing has been a primary drive to search for new anti-HD drugs. Numerous molecular targets along with a wide range of small molecules and gene therapies are currently under clinical investigation. More than 200 clinical studies are underway for HD, 75% are interventional, and 25% are observational studies. The present review discusses the small molecule clinical pipeline and molecular targets for HD. Furthermore, the biomarkers, diagnostic tests, gene therapies, behavioral and observational studies for HD were also deliberated., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Huntington's disease (HD) is a rare neurodegenerative disorder with protean clinical manifestations. Its management is challenging, consisting mainly of off-label treatments., Objectives: The International Parkinson and Movement Disorder Society commissioned a task force to review and evaluate the evidence of available therapies for HD gene expansion carriers., Methods: We followed the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Eligible randomized controlled trials were identified via an electronic search of the CENTRAL, MEDLINE, and EMBASE databases. All eligible trials that evaluated one or more of 33 predetermined clinical questions were included. Risk of bias was evaluated using the Cochrane Risk of Bias tool. A framework was adapted to allow for efficacy and safety conclusions to be drawn from the balance between the GRADE level of evidence and the importance of the benefit/harm of the intervention., Results: Twenty-two eligible studies involving 17 interventions were included, providing data to address 8 clinical questions. These data supported a likely effect of deutetrabenazine on motor impairment, chorea, and dystonia and of tetrabenazine on chorea. The data did not support a disease-modifying effect for premanifest and manifest HD. There was no eligible evidence to support the use of specific treatments for depression, psychosis, irritability, apathy, or suicidality. Similarly, no evidence was eligible to support the use of physiotherapy, occupational therapy, exercise, dietary, or surgical treatments., Conclusions: Data for therapeutic interventions in HD are limited and support only the use of VMAT2 inhibitors for specific motor symptoms. © 2021 International Parkinson and Movement Disorder Society., (© 2021 International Parkinson and Movement Disorder Society.)

Recent research has provided strong evidence that neurodegeneration may develop from an imbalance between synaptic structural components in the brain. Lately, inhibitory synapses communicating via the neurotransmitters GABA or glycine have come to the center of attention. Increasing evidence suggests that imbalance in the structural composition of inhibitory synapses affect deeply the ability of neurons to communicate effectively over synaptic connections. Progressive failure of synaptic plasticity and memory are thus hallmarks of neurodegenerative diseases. In order to prove that structural changes at synapses contribute to neurodegeneration, we need to visualize single-molecule interactions at synaptic sites in an exact spatial and time frame. This visualization has been restricted in terms of spatial and temporal resolution. New developments in electron microscopy and super-resolution microscopy have improved spatial and time resolution tremendously, opening up numerous possibilities. Here we critically review current and recently developed methods for high-resolution visualization of inhibitory synapses in the context of neurodegenerative diseases. We present advantages, strengths, weaknesses, and current limitations for selected methods in research, as well as present a future perspective. A range of new options has become available that will soon help understand the involvement of inhibitory synapses in neurodegenerative disorders.

Vesicular monoamine transporter 2 (VMAT2) is essential for synaptic transmission of all biogenic amines in the brain including serotonin, norepinephrine, histamine, and dopamine (DA). Given its crucial role in the neurophysiology and pharmacology of the central nervous system, VMAT2 is recognized as an important therapeutic target for various neurological disorders such as tardive dyskinesia (TD). Here, a novel series of dihydrotetrabenazine derivative analogs were designed and synthesized to evaluate their effects on [ 3 H]dihydrotetrabenazine (DTBZ) binding and [ 3 H]DA uptake at VMAT2. Of these analogs, compound 13e showed a high binding affinity for VMAT2 (IC 50  = 5.13 ± 0.16 nM) with excellent inhibition of [ 3 H]DA uptake (IC 50  = 6.04 ± 0.03 nM) in striatal synaptosomes. In human liver microsomes, 13e was more stable (T 1/2  = 161.2 min) than other reported VMAT2 inhibitors such as DTBZ (T 1/2  = 119.5 min). In addition, 13e effectively inhibited the spontaneous locomotor activity (percent inhibition at 3 μmol/kg = 64.7%) in Sprague-Dawley rats. Taken together, our results indicate that 13e might be a promising lead compound for the development of novel treatments of TD., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

Importance: Tourette syndrome is a neurodevelopmental disorder characterized by childhood onset of motor and phonic tics, often accompanied by behavioral and psychiatric comorbidities. Deutetrabenazine is a vesicular monoamine transporter 2 inhibitor approved in the US for the treatment of chorea associated with Huntington disease and tardive dyskinesia., Objective: To report results of the ARTISTS 2 (Alternatives for Reducing Tics in Tourette Syndrome 2) study examining deutetrabenazine for treatment of Tourette syndrome., Design, Setting, and Participants: This phase 3, randomized, double-blind, placebo-controlled, parallel-group, fixed-dose study was conducted over 8 weeks with a 1-week follow-up (June 21, 2018, to December 9, 2019). Children and adolescents aged 6 to 16 years with a diagnosis of Tourette syndrome and active tics causing distress or impairment were enrolled in the study. Children were recruited from 52 sites in 10 countries. Data were analyzed from February 4 to April 22, 2020., Interventions: Participants were randomized (1:1:1) to low-dose deutetrabenazine (up to 36 mg/d), high-dose deutetrabenazine (up to 48 mg/d), or a matching placebo, which were titrated over 4 weeks to the target dose followed by a 4-week maintenance period., Main Outcomes and Measures: The primary efficacy end point was change from baseline to week 8 in the Yale Global Tic Severity Scale-Total Tic Score (YGTSS-TTS) for high-dose deutetrabenazine. Key secondary end points included changes in YGTSS-TTS for low-dose deutetrabenazine, Tourette Syndrome Clinical Global Impression score, Tourette Syndrome Patient Global Impression of Impact score, and Child and Adolescent Gilles de la Tourette Syndrome-Quality of Life Activities of Daily Living subscale score. Safety assessments included incidence of treatment-emergent adverse events, laboratory parameters, vital signs, and questionnaires., Results: The study included 158 children and adolescents (mean [SD] age, 11.7 [2.6] years). A total of 119 participants (75%) were boys; 7 (4%), Asian; 1 (1%), Black; 32 (20%), Hispanic; 4 (3%), Native American; 135 (85%), White; 2 (1%), multiracial; 9 (6%), other race; and 1 (0.6%), of unknown ethnic origin. Fifty-two participants were randomized to the high-dose deutetrabenazine group, 54 to the low-dose deutetrabenazine group, and 52 to the placebo group. Baseline characteristics for participants were similar between groups. Of the total 158 participants, 64 (41%) were aged 6 to 11 years, and 94 (59%) were aged 12 to 16 years at baseline. Mean time since Tourette syndrome diagnosis was 3.3 (2.8) years, and mean baseline YGTSS-TTS was 33.8 (6.6) points. At week 8, the difference in YGTSS-TTS was not significant between the high-dose deutetrabenazine and placebo groups (least-squares mean difference, -0.8 points; 95% CI, -3.9 to 2.3 points; P = .60; Cohen d, -0.11). There were no nominally significant differences between groups for key secondary end points. Treatment-emergent adverse events were reported for 34 participants (65%) treated with high-dose deutetrabenazine, 24 (44%) treated with low-dose deutetrabenazine, and 25 (49%) treated with placebo and were generally mild or moderate., Conclusions and Relevance: In this fixed-dose randomized clinical trial of deutetrabenazine in children and adolescents with Tourette syndrome, the primary efficacy end point was not met. No new safety signals were identified., Trial Registration: ClinicalTrials.gov Identifier: NCT03571256.

Background: Individuals with tardive dyskinesia (TD) who completed a long-term study (KINECT 3 or KINECT 4) of valbenazine (40 or 80 mg/day, once-daily for up to 48 weeks followed by 4-week washout) were enrolled in a subsequent study (NCT02736955) that was primarily designed to further evaluate the long-term safety of valbenazine., Methods: Participants were initiated at 40 mg/day (following prior valbenazine washout). At week 4, dosing was escalated to 80 mg/day based on tolerability and clinical assessment of TD; reduction to 40 mg/day was allowed for tolerability. The study was planned for 72 weeks or until termination due to commercial availability of valbenazine. Assessments included the Clinical Global Impression of Severity-TD (CGIS-TD), Patient Satisfaction Questionnaire (PSQ), and treatment-emergent adverse events (TEAEs)., Results: At study termination, 85.7% (138/161) of participants were still active. Four participants had reached week 60, and none reached week 72. The percentage of participants with a CGIS-TD score ≤2 (normal/not ill or borderline ill) increased from study baseline (14.5% [23/159]) to week 48 (64.3% [36/56]). At baseline, 98.8% (158/160) of participants rated their prior valbenazine experience with a PSQ score ≤2 (very satisfied or somewhat satisfied). At week 48, 98.2% (55/56) remained satisfied. Before week 4 (dose escalation), 9.4% of participants had ≥1 TEAE. After week 4, the TEAE incidence was 49.0%. No TEAE occurred in ≥5% of participants during treatment (before or after week 4)., Conclusions: Valbenazine was well-tolerated and persistent improvements in TD were found in adults who received once-daily treatment for >1 year.

Introduction Chorea is a common motor manifestation of Huntington's disease (HD). Two vesicular monoamine transporter type 2 (VMAT-2) inhibitors have been approved by the FDA for treatment of HD chorea, and a third is currently being assessed in a phase 3 trial. Antipsychotic therapies are used off-label for treatment of chorea and can treat comorbid psychiatric symptoms. There is considerable clinical equipoise regarding the safe and effective treatment of chorea and comorbid symptoms in HD. Areas covered : The authors review existing medications used to treat HD chorea in the United States of America (USA). Implications for common comorbid symptoms (e.g. psychiatric, metabolic) are also discussed. Available therapies vary widely in cost, dosing frequency, and off -target effects, both beneficial or negative. Expert opinion : Treatment considerations for chorea should account for patient comorbidities. The authors recommend prospective, observational clinical effectiveness studies which can evaluate the long-term comparative effectiveness and safety of VMAT-2 inhibitors and antipsychotics in HD. Data regarding safety of dual therapy is another critical need. This is especially timely given the changing landscape of HD therapies which may increase cost burden and possibly extend both asymptomatic and symptomatic years for HD patients.

Introduction : Significant need exists for effective, well-tolerated pharmacologic treatments for Tourette syndrome (TS). Medications that inhibit vesicular monoamine transporters (i.e. VMAT2 inhibitors) downregulate presynaptic packaging and release of dopamine into the neuronal synapse and are effective in treating hyperkinetic movement disorders such as Huntington's chorea and tardive dyskinesia (TD); thus, they may be useful in treating TS. Areas covered : This review describes the clinical program evaluating the safety and efficacy of valbenazine in the treatment of involuntary tics associated with TS in adult and pediatric subjects. While there was a trend in the 6 completed trials toward greater improvement in valbenazine-treated versus placebo subjects on the primary efficacy endpoint (Yale Global Tic Severity Scale Total Tic Score), this difference did not reach statistical significance. Valbenazine was generally well-tolerated in the studies, and treatment-emergent adverse events were consistent with valbenazine studies in TD. Expert opinion : Due to the failure to meet the primary endpoint in these trials, further investigation of valbenazine for TS is unlikely. Given the need for safe and effective TS therapies and the key role of VMAT2 in modulating dopaminergic activity, it is reasonable for future studies to investigate other VMAT2 inhibitors as potential treatments for TS.

Introduction : Tardive dyskinesia (TD) is a hyperkinetic movement disorder that arises as a complication of exposure to dopamine receptor blocking agents. Vesicular monoamine transporter type 2 (VMAT2) inhibitors reduce dyskinesia by decreasing transport of monoamines, including dopamine, into presynaptic vesicles, leaving unpackaged dopamine to be metabolized by monoamine oxidase. Deutetrabenazine was adapted from an earlier VMAT2 inhibitor, tetrabenazine, by substituting three deuterium isotopes in place of three hydrogen isotopes at the site of metabolic degradation to improve upon the pharmacokinetics of the parent compound. Areas covered : The authors reviewed the pivotal trials examining the safety and efficacy of deutetrabenazine, as well as long-term data from an open-label extension. Also reviewed were posters and oral presentations, as well as information from the product label and the United States Food and Drug Administration. Expert opinion : Deutetrabenazine is effective at decreasing dyskinesia in TD, but drug selection and cost-effectiveness between existing VMAT2 inhibitors are evolving areas of study. Other areas of investigation include novel anti-dyskinetic agents and use of deep brain stimulation.

Aims: To evaluate clinical and economic outcomes associated with valbenazine compared with deutetrabenazine in patients with tardive dyskinesia (TD) using a model that accounts for multiple dimensions of patient health status., Materials and Methods: A discretely integrated condition event model was developed to evaluate the cost-effectiveness of treatment with valbenazine and deutetrabenazine in a synthetic cohort of 1,000 patients with TD who were receiving antipsychotic medication to treat an underlying psychiatric disorder. Clinical inputs were derived from relevant clinical trials or from publicly available sources. Patients were assessed over 1 year using ≥50% improvement from baseline in Abnormal Involuntary Movement Scale (AIMS) total score as the primary definition of response. Response at 1 year using Clinical Global Impression of Change (CGIC) score ≤2 was also assessed. Health outcomes included quality-adjusted life years (QALYs), life years, proportion responding to treatment at 1 year, and number of psychiatric relapses., Results: Regardless of the definition used for response, patients treated with valbenazine were more likely to have responded to treatment at 1 year, lived longer, and accrued more QALYs than patients who received deutetrabenazine. Using the AIMS response criterion, the incremental cost-effectiveness ratio was $9,951/QALY for valbenazine compared with deutetrabenazine. By comparison, using the CGIC response criterion valbenazine dominated deutetrabenazine with valbenazine-treated patients accumulating more QALYs (3.4 vs 3.3 years) and incurring lower lifetime costs ($252,311 vs $283,208) than deutetrabenazine-treated patients., Limitations: There are no head-to-head trials of valbenazine and deutetrabenazine, so probabilities of response used in the model were calculated based on an indirect treatment comparison of results from individual trials with one drug or the other, using only those metrics reported across trials., Conclusions: In patients with TD, treatment with valbenazine is highly cost-effective compared with deutetrabenazine.

Background: Copulatory or pelvic thrusting dyskinesia is a subtype of tardive dyskinesia (TD) which is caused by exposure to dopamine blocking agents., Phenomenology Shown: A man exhibiting rhythmic, stereotypical pelvic thrusting movements., Educational Value: Recognition of copulatory dyskinesia as a distinctive iatrogenic disorder helps prevent unnecessary investigations and guides the implementation of corrective strategies., Competing Interests: The author has no competing interests to declare., (Copyright: © 2020 The Author(s).)

​​ Tardive dyskinesia (TD) is a condition of potentially irreversible abnormal involuntary movements associated with dopamine receptor blocking agents, such as antipsychotics. While prevention is the best strategy, it is not always possible. This report outlines strategies to reduce TD symptoms, including the use of the FDA-approved treatment options (valbenazine and deutetrabenazine)., (© Copyright 2020 Physicians Postgraduate Press, Inc.)

Tetrabenazine reduces chorea symptoms associated with Huntington's disease by depleting monoamines in pre-synaptic vesicles. It exhibits low aqueous solubility and undergoes first pass metabolism due to which it has low oral bioavailability. The aim of present work was to formulate intranasal tetrabenazine loaded nanoemulsion for better management and treatment of hyperkinesia related with Huntington's disease. A quality by design (QbD) technique was employed as statistical multivariate approach for formulation and optimization of nanoemulsion. Optimized formulation showed droplet size of 106.80 ± 1.96 nm with polydispersity index (PDI) value of 0.198 ± 0.005 and -9.63 ± 0.63 mV zeta potential. Ex-vivo drug permeation studies were carried out and found that the formulation has an augmented permeation by 1.68 times as compared to tetrabenazine suspension. MTT assay on neuro-2a cell lines showed that tetrabenazine loaded nanoemulsion displayed better cell viability than placebo and aqueous drug solution at ½ × C max , C max and 2 × C max . Pharmacokinetic parameters in brain after intranasal administration of tetrabenazine nanoemulsion were found to be C max  = 3.497 ± 0.275 μg/mL, AUC 0-12 = 29.196 ± 0.870 μg h/mL and elimination rate constant (k e ) = 0.097 ± 0.012 h -1 where as in plasma the pharmacokinetic parameters were C max  = 1.400 ± 0.084 μg/mL, AUC 0-12  = 12.925 ± 0.340 μg h/mL and k e  = 0.061 ± 0.010 h -1 . Histopathological studies of porcine nasal mucosa showed that nasal mucosa remains intact when treated with tetrabenazine loaded nanoemulsion. Thus it can be concluded from study that optimized nanoemulsion formulation of a tetrabenazine was robust and its delivery through nasal route is a viable alternative to other routes of administration for treatment of hyperkinesia associated with Huntington's disease., Competing Interests: Declaration of Competing Interest The authors report no conflicts of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Hyperkinetic movement disorders comprise a variety of conditions characterized by involuntary movements, which include but are not limited to tardive dyskinesia, chorea associated with Huntington's Disease, and tic disorders. The class of medications that have been used to treat these conditions includes Vesicular Monoamine Transporter-2 (VMAT2) inhibitors. In 2008, the FDA approved tetrabenazine as a treatment for chorea associated with Huntington's Disease. Optimization of the pharmacology of tetrabenazine has since led to the approval of two new VMAT2 inhibitors, deutetrabenazine and valbenazine. The objective of this review is to provide background on the role of VMAT in monoamine neurotransmission, the mechanism of VMAT2 inhibition on the treatment of hyperkinetic disorders (specifically tardive dyskinesia and chorea associated with Huntington's Disease), the pharmacology and pharmacokinetics of the commercially available VMAT2 inhibitors, and a summary of the clinical data to support application of these medications., Competing Interests: Declaration of Competing Interest Dr. Jessa Koch has no conflicts of interest to disclose. Dr. Wei-Xing Shi has no conflicts of interest to disclose. Dr. Khashayar Dashtipour reported receiving compensation to serve as an advisor and/or speaker for Allergan, AbbVie, Acadia, Acorda Therapeutics, Adamas Pharmaceuticals Inc., Amneal, Kyowa Kirin, Ipsen, Lundbeck, Neurocrine Biosciences, Teva Pharmaceutical Industries Ltd., and US WorldMeds., (Copyright © 2020. Published by Elsevier Inc.)

Tardive syndromes (TDS) are a group of hyperkinetic and hypokinetic movement disorders that occurs after exposure to dopamine receptor blocking agents such as antipsychotic and antiemetic drugs. The Abnormal Involuntary Movement Scale (AIMS) is a widely used instrument that has become the standard for assessment of tardive dyskinesia (TDD), the most common form of TDS. However, the AIMS has a number of clinimetric limitations and was designed primarily to assess the anatomic distribution and severity of involuntary movements without regard to phenomenology. To build on recent advances in understanding and treatment of TDS, re-evaluation and revision of the AIMS that could aid both clinical practice and research may be worthwhile. Challenges, such as retaining the efficiency of the current AIMS, incorporating evaluation of impairment in daily activities, and re-training clinicians for a revised examination procedure and rating instrument, are very likely surmountable., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Competing Interests: Competing interests: None declared.

Tardive dyskinesia (TD) is an iatrogenic condition that encompasses a wide phenomenological spectrum of movement disorders caused by exposure to dopamine receptor blocking agents (DRBAs). TD may cause troublesome or disabling symptoms that impair quality of life. Due to frequent, often inappropriate, use of DRBAs, TD prevalence rates among patients exposed to DRBAs continue to be high. The judicious use of DRBAs is key to the prevention of TD, reduction of disease burden, and achieving lasting remission. Dopamine-depleting vesicular monoamine transporter type 2 inhibitors are considered the treatment of choice of TD., Competing Interests: Disclosure Dr H.H. Bashir has nothing to disclose. Dr J. Jankovic has received research/training funding from Allergan; CHDI Foundation; Dystonia Coalition; F. Hoffmann-La Roche Ltd; Huntington Study Group; Medtronic Neuromodulation; Merz Pharmaceuticals; Michael J Fox Foundation for Parkinson Research; National Institutes of Health; Neurocrine Biosciences; Parkinson's Foundation; Parkinson Study Group; Revance Therapeutics, Inc; and Teva Pharmaceutical Industries. He has served as a consultant/advisory board member for Abide; Aeon BioPharma; Nuvelution; Retrophin; and Teva Pharmaceutical Industries Ltd. He has served on editorial boards of Expert Review of Neurotherapeutics; Journal of Parkinson’s Disease; Medlink; Neurology in Clinical Practice; The Botulinum Journal; PeerJ; Therapeutic Advances in Neurologic Disorders; Neurotherapeutics; Tremor and Other Hyperkinetic Movements; Toxins; and UpToDate. He has received royalties from Cambridge; Elsevier; Future Science Group; Hodder Arnold; Medlink: Neurology; Lippincott Williams and Wilkins; and Wiley-Blackwell., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Valbenazine, a vesicular monoamine transporter 2 (VMAT2, SLC18A2) inhibitor, is a newly approved treatment for tardive dyskinesia. VMAT2 is present in the membrane of secretory vesicles and transports dopamine (DA), norepinephrine (NE), serotonin (5-HT), histamine, glutamate (Glu), and GABA into vesicles for presynaptic release. We utilized microdialysis in awake, freely moving mice to determine the effect of NBI-98782, the active metabolite of valbenazine, alone, or in combination with several antipsychotic drugs (APDs), to influence neurotransmitter efflux in the medial prefrontal cortex (mPFC), dorsal striatum (dSTR), hippocampus and nucleus accumbens (NAC); we also compared it with tetrabenazine, the prototypical VMAT2 inhibitor. Acute NBI-98782 and tetrabenazine decreased mPFC, dSTR, hippocampus, and NAC DA, 5-HT, and NE efflux, while increasing that of DOPAC, HVA, and 5-HIAA. Sub-chronic NBI-98782 (7 days) decreased baseline DA and 5-HT efflux in both mPFC and dSTR. NBI-98782 elicited similar effects on neurotransmitter efflux in sub-chronic NBI-98782-treated mice but also enhanced ACh and GABA; the decrease in DA efflux in mPFC and dSTR was not significant in the sc-treated animals. NBI-98782 suppressed clozapine-, olanzapine- and risperidone-induced DA efflux in both mPFC and dSTR, and ACh efflux in mPFC. NBI-98782 suppressed the haloperidol-induced DA efflux in dSTR, with minimal effect on GABA efflux. NBI-98782 attenuated PCP-induced DA, 5-HT, NE and Glu efflux, and AMPH-induced DA and NE efflux, in both mPFC and dSTR, as well as PCP- and AMPH-induced hyperlocomotion, suggesting possible beneficial antipsychotic effects., (Copyright © 2020. Published by Elsevier Inc.)

Objective: To evaluate the effects of once-daily valbenazine (40 or 80 mg/d) in older and younger adults with tardive dyskinesia (TD)., Methods: Data were pooled from three 6-week, randomized, double-blind, placebo-controlled (DBPC) studies (KINECT [NCT01688037], KINECT 2 [NCT01733121], and KINECT 3 [NCT02274558]) and two long-term studies (KINECT 3 extension and KINECT 4 [NCT02405091]). Outcomes analyzed in older and younger participants (55 years or older and younger than 55 years, respectively) included Abnormal Involuntary Movement Scale (AIMS) response (threshold of greater than or equal to 50% improvement from baseline in total score [items 1 to 7]) and Clinical Global Impression of Change-Tardive Dyskinesia (CGI-TD) response (score 2 or less ["very much improved" or "much improved"]). Safety assessments included treatment-emergent adverse events (TEAEs)., Results: At week 6 (end of DBPC treatment), the percentage of participants who met the AIMS response threshold was higher with valbenazine versus placebo in both subgroups: 55 years or older (80 mg/d, 39.7% [P < .001]; 40 mg/d, 28.6% [P < .01]; placebo, 9.7%); younger than 55 years (80 mg/d, 39.5% [P < .001]; 40 mg/d, 20.0% [P > .05]; placebo, 10.8%). The percentage of participants with CGI-TD response was also higher with valbenazine versus placebo: 55 years or older (80 mg/d, 41.3% [P < .01]; 40 mg/d, 30.2% [P > .05]; placebo, 19.4%); younger than 55 years (80 mg/d, 39.5% [P < .05]; 40 mg/d, 35.3% [P < .05]; placebo, 18.5%). Responses at week 48 (end of long-term treatment, combined doses) were as follows: 55 years or older (AIMS, 70.7%; CGI-TD, 82.8%); younger than 55 years (AIMS, 58.7%; CGI-TD, 72.3%). No significant differences between older and younger subgroups were found for AIMS or CGI-TD response. No new safety signals or TEAEs of clinical concern were found in older participants who received long-term treatment., Conclusions: Valbenazine improved TD and was generally well tolerated in older and younger adults., (© 2019 The Authors. International Journal of Geriatric Psychiatry published by John Wiley & Sons Ltd.)

Tardive dyskinesia (TD), a condition characterized by involuntary movements, is found in patients taking antipsychotics or other agents that block dopamine receptors. Symptoms of TD are associated with reduced quality of life, psychosocial problems, and medication nonadherence. Few agents tested in the treatment of TD had sufficient data to support or refute their use, until recently. A review of new evidence was combined with the existing guideline to provide new treatment recommendations. This activity provides an overview of treatments for patients with TD, including valbenazine and deutetrabenazine, which both received FDA approval for the treatment of TD., (© Copyright 2019 Physicians Postgraduate Press, Inc.)

Introduction : Huntington's disease (HD)-associated chorea and tardive dyskinesia (TD) are hyperkinetic movement disorders that can have deleterious effects on patients' quality of life (QoL). Deutetrabenazine, a vesicular monoamine transporter 2 (VMAT2) inhibitor, was approved by the US Food and Drug Administration (FDA) for the treatment of HD-associated chorea and TD. It is structurally similar to tetrabenazine, an FDA-approved compound for treatment of chorea that is widely used off-label for treatment of TD, but has deuterium modifications that improve its pharmacokinetic profile. Areas covered : Herein, the authors cover the key clinical trials with deutetrabenazine in patients with HD-associated chorea (First-HD and ARC-HD) and in patients with TD (ARM-TD, AIM-TD, and RIM-TD). Expert opinion : Deutetrabenazine demonstrates consistent efficacy across patient types regardless of underlying psychiatric illness, or through use of dopamine-receptor antagonists (DRAs), which are the primary cause of TD. The safety profile of deutetrabenazine in clinical trials is similar to that of placebo. Long-term extension studies in both HD-associated chorea and TD show consistent efficacy and safety. Deutetrabenazine will likely be an integral part of the treatment strategy for HD-associated chorea and TD. Meanwhile, its potential to treat other hyperkinetic movement disorders is still under investigation.

Objective: To evaluate the long-term safety and efficacy of deutetrabenazine in patients with tardive dyskinesia (TD)., Method: Patients with TD who completed the 12 week, phase 3, placebo-controlled trials were eligible to enter this open-label, single-arm study. The open-label study consisted of a 6 week dose-escalation phase and a long-term maintenance phase (clinic visits at Weeks 4, 6 and 15, and every 13 weeks until Week 106). Patients began deutetrabenazine at 12 mg/day, titrating up to a dose that was tolerable and provided adequate dyskinesia control, based on investigator judgement, with a maximum allowed dose of 48 mg/day (36 mg/day for patients taking strong cytochrome P450 2D6 (CYP2D6) inhibitors). Safety measures included incidence of adverse events (AEs) and scales used to monitor parkinsonism, akathisia/restlessness, anxiety, depression, suicidality and somnolence/sedation. Efficacy endpoints included the change in Abnormal Involuntary Movement Scale (AIMS) score (items 1 to 7) from baseline and the proportion of patients rated as 'Much Improved' or 'Very Much Improved' on the Clinical Global Impression of Change., Results: A total of 343 patients enrolled in the extension study, and there were 331 patient-years of exposure in this analysis. The exposure-adjusted incidence rates of AEs with long-term treatment were comparable to or lower than those observed in the phase 3 trials. The mean (SE) change in AIMS score was -4.9 (0.4) at Week 54 (n = 146), - 6.3 (0.7) at Week 80 (n = 66) and -5.1 (2.0) at Week 106 (n = 8)., Conclusions: Overall, long-term treatment with deutetrabenazine was efficacious, safe, and well tolerated in patients with TD., Trial Registration Number: NCT02198794., Competing Interests: Competing interests: HHF has received honoraria from Prime Education, Inc, International Parkinson and Movement Disorders Society, Carling Communications, Medscape (speaker in CME events), AbbVie, Biogen, GE Health Care, Inventiv, Kyowa Hakko Kirin, Lundbeck, Merz Pharmaceuticals, Voyager, Sunovion, Pfizer Pharmaceuticals (as a consultant). He has received grant and research support from: AbbVie, Acadia, Teva, Biotie/Acorda Therapeutics, Civitas, Kyowa/Prostrakan, Michael J. Fox Foundation, Movement Disorders Society, NIH/NINDS, Parkinson Study Group, Rhythm, Synosia; he has no owner interest in any pharmaceutical company. He has received royalties from: Demos Publishing (serving as a book author/editor). The Cleveland Clinic has a contract with Teva for his role as a Co-Principal Investigator in SD-809 tardive dyskinesia global studies. He also serves as a member of the publication committee for Acorda Pharmaceuticals but does not receive any personal compensation for this. He receives a stipend from the International Parkinson and Movement Disorders Society for serving as Medical Editor of the MDS Web Site. DS is a former employee of Teva Pharmaceuticals; he has received salary and benefits from Auspex Pharmaceuticals, and has patents pending: US20160346270, US20160287574. MDD is an employee of Teva Pharmaceuticals. SAF has received honoraria from Neurocrine, Lundbeck, Teva, Avanir, UCB, US WorldMeds, Sunovion, Adamas; he has received research support from Ipsen, Medtronic, Auspex, US WorldMeds, Pharm-Olam, Cynapsus Therapeutics/Sunovion, Vaccinex, Solstice, CHDI Foundation, Michael J. Fox Foundation, NIH; he has received royalties from Demos, Blackwell Futura for textbooks, and UpToDate. RAH has served as a consultant for Teva Pharmaceuticals, AbbVie, Inc, Acorda Therapeutics, Adamas Pharmaceuticals, AstraZeneca, Biotie Therapies, Cynapsus Therapeutics, Impax Laboratories, Inc, Lundbeck LLC, Michael J Fox Foundation, Neurocrine Biosciences, Neuropore Therapies, Pfizer Inc, Prexton Therapeutics, US WorldMeds, Guidepoint Global, Gerson Lehrman Group (GLG), LCN Consulting, Putnam Associates, National Parkinson Foundation, eResearch Technology, Inc, Sarepta Therapeutics, Back Bay Life Science, National Institutes of Health, Projects in Knowledge, Vista Research, LifeMax, Peerview Press, ClinicalMind Medical and Therapeutic Communications, Sunovion Pharmaceuticals, Academy for Continued Healthcare Learning, Outcomes Insights, Expert Connect, HealthLogix, Cowen and Company, Pharma Two B, Ltd, RMEI Medical Education for Better Outcomes, ClearView Healthcare Partners, Health Advances, Kyowa Kirin Pharmaceutical Development, Ltd, Quintiles, and Eli Lilly and Company. JJ-S has received research support from Acadia Pharmaceuticals, St. Jude Medical, Biotie, Michael J. Fox Foundation; she has served as a consultant for Teva, St. Jude Medical, Medtronic; she has also received honoraria from Vindico Medical Education. WGO has received research support from Lundbeck, Tremor Research Group, Dystonia Coalition, Restless Leg Syndrome Foundation, Acorda. Speakers’ Bureau: Teva, Lundbeck, UCB, US WorldMeds; he has served as a consultant for Teva, Lundbeck, Acadia. LFJ has received grant support Auspex/Teva, Boehringer Ingelheim, Otsuka, NIH; he has served as a consultant for Roche. SWW has received research support from Teva, Pfizer; he has served as a consultant for Boehringer Ingelheim, Nutria Health. DB has received research support from National Parkinson Foundation; he has served on the speaker’s bureau for Teva Pharmaceuticals and Acadia Pharmaceuticals, Inc; he has served as a consultant for Teva, Cynapsus, Acadia. MSL has served on the speakers’ bureau for Lundbeck, Acadia, and Teva; he has served as a consultant for Teva Neuroscience, US WorldMeds, the Mayo Clinic, Starnes-Davis-Florie, Elite Medical Experts, Spears, Moore, Rebman receives research support from the National Institutes of Health (R01 NS082296, R21 GM118962, U54 TR001456, 5U01 NS090259), Department of Defense (W81XWH-17-1-0062), Michael J. Fox Foundation, Dorothy/Daniel Gerwin Parkinson’s Research Fund, Auspex, Teva, Acorda, US WorldMeds, Axovant and CHDI; and receives royalty payments from Elsevier for editing ‘Animal Models of Movement Disorders’ and ‘Movement Disorders: Genetics and Models.’ DRS has served as a consultant for Eli Lilly, Teva, Lundbeck, and Weston Brain Institute; he has received speaker’s fees from Acadia, Baylor College of Medicine, the Arizona Psychiatric Society, Lundbeck, Teva US World Meds and the Tourette Association of America; he has received research support from Arizona Alzheimer’s Consortium, Axovant, Biotie, Intec, Kyowa, Teva, US WorldMeds, Neurocrine, Michael J. Fox Foundation, and the NIH. KEA has served as a scientific adviser and was the North American study Co-Principal Investigator for LEGATO-HD, Global Principal Investigator for AIM-TD, and Global Co-Principal Investigator for ARM-TD; she was the site Principal Investigator for Pride-HD, First-HD, ARC-HD for Teva; she was the scientific advisor and site Principal Investigator for ENROLL-HD for CHDI Foundation; she was a scientific advisor for Prana and site Principal Investigator for Vaccinex; she served as a consultant for the NeuroNext 105 study for Azevan; she has received salary support from the Griffin Foundation. She has also received honoraria from Vindico Medical Education., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Aim: Utilize the Bucher indirect treatment comparison (ITC) method to compare valbenazine and deutetrabenazine efficacy using clinical trial data. Methods: Outcomes included mean change from baseline in Abnormal Involuntary Movement Scale (AIMS) total score, AIMS response (≥50% improvement), clinical global impression of change response (score ≤2) and safety outcomes. Data were pooled by trial and dose; outcomes were analyzed at multiple time points. Results: ITC of AIMS score improvement significantly favored valbenazine 80 mg/day at 6 weeks versus deutetrabenazine 36 mg/day at 8 weeks, while valbenazine 40 mg/day was statistically similar to all doses of deutetrabenazine at all time points. No significant differences between drugs were found in AIMS and clinical global impression of change responses and safety outcomes. Conclusion: In this ITC of pooled trial data, valbenazine was generally favorable over deutetrabenazine, although dose titration and equivalency should be considered when interpreting results.

Purpose of Review: Tardive dyskinesia (TD) is caused by exposure to medications with dopamine antagonism, mainly antipsychotics. It often distresses individuals, physically and emotionally and affects their quality of life. We evaluated peer-reviewed recently published articles with a goal of providing a critically appraised update on the latest advancements in this field., Recent Findings: In 2017, FDA approved VMAT2 inhibitors, deutetrabenazine and valbenazine. They have demonstrated efficacy in several class 1 studies. Also there have been update in the evidence-based guidelines for treatment for tardive dyskinesia. Various medication classes are being used for treatment of TD with VMAT2 inhibitors to be first FDA-approved medications. Their use should be tailored to the individual patient. Long-term studies will further guide us in how to optimize treatment, especially in the real-world setting. As clinicians, we need to take into consideration all aspects of symptomatology, etiology, potential side effects of the medications, to find the best possible "match" for our patients.

Background: A minimal clinically important difference has not been established for the Abnormal Involuntary Movement Scale in patients with tardive dyskinesia. Valbenazine is a vesicular monoamine transporter 2 inhibitor approved for the treatment of tardive dyskinesia in adults. Efficacy in randomized, double-blind, placebo-controlled trials was defined as the change from baseline in Abnormal Involuntary Movement Scale total score (sum of items 1-7)., Objectives: To estimate an minimal clinically important difference for the Abnormal Involuntary Movement Scale using valbenazine trial data and an anchor-based method., Methods: Data were pooled from three 6-week double-blind, placebo-controlled trials: KINECT (NCT01688037), KINECT 2 (NCT01733121), and KINECT 3 (NCT02274558). Valbenazine doses were pooled for analyses as follows: "low dose," which includes 40 or 50 mg/day; and "high dose," which includes 75 or 80 mg/day. Mean changes from baseline in Abnormal Involuntary Movement Scale total score were analyzed in all participants (valbenazine- and placebo-treated) with a Clinical Global Impression of Change-Tardive Dyskinesia or Patient Global Impression of Change score of 1 (very much improved) to 3 (minimally improved)., Results: The least squares mean improvement from baseline to week 6 in Abnormal Involuntary Movement Scale total score was significantly greater with valbenazine (low dose: -2.4; high dose: -3.2; both, P < 0.001) versus placebo (-0.7). An minimal clinically important difference of 2 points was estimated based on least squares mean changes in Abnormal Involuntary Movement Scale total score in participants with a Clinical Global Impression of Change-Tardive Dyskinesia score ≤3 at week 6 (mean change: -2.2; median change: -2) or Patient Global Impression of Change score ≤3 at week 6 (mean change: -2.0; median change: -2)., Conclusions: Results from an anchor-based method indicate that a 2-point decrease in Abnormal Involuntary Movement Scale total score may be considered clinically important. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society., (© 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.)

Background: Tardive dyskinesia is a movement disorder characterised by irregular, stereotyped, and choreiform movements associated with the use of antipsychotic medication. We aim to provide recommendations on the treatment of tardive dyskinesia., Methods: We performed a systematic review of studies of the treatment of tardive dyskinesia. Studies were rated for methodological quality using the American Academy of Neurology Risk of Bias Classification system. Overall level of evidence classifications and grades of recommendation were made using the Scottish Intercollegiate Guidelines Network framework., Results: Preventing tardive dyskinesia is of primary importance, and clinicians should follow best practice for prescribing antipsychotic medication, including limiting the prescription for specific indications, using the minimum effective dose, and minimising the duration of therapy. The first-line management of tardive dyskinesia is the withdrawal of antipsychotic medication if clinically feasible. Yet, for many patients with serious mental illness, the discontinuation of antipsychotics is not possible due to disease relapse. Switching from a first-generation to a second-generation antipsychotic with a lower D2 affinity, such as clozapine or quetiapine, may be effective in reducing tardive dyskinesia symptoms. The strongest evidence for a suitable co-intervention to treat tardive dyskinesia comes from tests with the new VMAT inhibitors, deutetrabenazine and valbenazine. These medications have not been approved for use in Canada., Conclusion: Data on tardive dyskinesia treatment are limited, and the best management strategy remains prevention. More long-term safety and efficacy data are needed for deutetrabenazine and valbenazine, and their routine availability to patients outside of the USA remains in question.

Tardive dyskinesia (TD), the choreoathetoid movements of fingers, arms, legs, and trunk and irregular stereotypical movements of the mouth, face, and tongue, has been the scourge of antipsychotic medications since the approval of chlorpromazine. TD tends to occur late in treatment and sometimes remains after discontinuation of the antipsychotic medication. With the recent approval of two medications, valbenazine (Ingrezza ® ) and deutetrabenazine (Austedo ® ), there are now treatments for this disfiguring consequence of dopamine-blocking medications. The current article distinguishes the movement disorder adverse effects of dopamine antagonists, explains the putative mechanism of action, and describes how best to treat TD with the new vesicular monamine transporter 2 (VMAT2) medications now approved by the U.S. Food and Drug Administration. [Journal of Psychosocial Nursing and Mental Health Services, 57(5), 11-14.]., (Copyright 2019, SLACK Incorporated.)

Objective: Most suicidality literature in Huntington disease (HD) is based on natural history studies or retrospective reviews, but reports on risk factors from clinical trials are limited., Methods: We analyzed 609 participants from 2CARE, a randomized, double-blind, placebo-controlled clinical trial with up to 5 years of follow-up, for risk factors related to suicidality. The primary outcome variable was the time from randomization until the first occurrence of either suicidal ideation or attempt. We also considered time from randomization until the first suicide attempt as a secondary outcome variable., Results: Depression, anxiety, bipolar disorder, antidepressant or anxiolytic use, and prior suicide attempt at baseline were associated with time to ideation or attempt. Baseline employment status, marital status, CAG repeat length, tetrabenazine use, and treatment assignment (coenzyme Q 10 or placebo) were not associated with suicidality. Time-dependent variables from the Unified Huntington's Disease Rating Scale Behavioral Assessment were associated with time to suicidal ideation or attempt, driven mainly by items related to depressed mood, low self-esteem/guilt, anxiety, suicidal thoughts, irritability, and compulsions. Variables associated with time to suicide attempt alone were generally similar., Conclusion: These data suggest psychiatric comorbidities in HD are predictive of suicidal behavior while participating in clinical trials, reinforcing the importance of clinical surveillance and treatment towards lessening risk during participation and perhaps beyond. Designing a composite algorithm for early prediction of suicide attempts in HD may be of value, particularly given anticipated trials aimed at disease modification are likely to be long-term., Clinicaltrialsgov Identifier: NCT00608881., (© 2019 American Academy of Neurology.)