A Bioequivalence Comparison Between the Once-Daily Extended-Release Tablet and the Twice-Daily Tablet Formulations of Deutetrabenazine at Steady State

Deutetrabenazine is approved for the treatment of tardive dyskinesia and chorea associated with Huntington's disease. This study compared the exposure between the once-daily (test) and twice-daily (reference) formulations of deutetrabenazine under fed conditions. Using a randomized crossover design, healthy adults (n = 262) received the 24 mg of the test formulation once daily and 12 mg of the reference formulation twice daily, each for 7 days. Plasma concentrations were collected on Days 4-6 before dose intake, and frequently for pharmacokinetic evaluation on Days 6 and 7 for determination of deutetrabenazine and active metabolites, deuterated α-dihydrotetrabenazine (α-HTBZ) and β-dihydrotetrabenazine (β-HTBZ). Geometric mean ratios (GMRs, test/reference) were computed for all analytes, and bioequivalence was tested for area under the plasma concentration-time curve over 24 hours at steady state (AUC0-24 h,ss ) and for maximum plasma concentrations at steady state (Cmax,ss ). The GMRs for AUC0-24 h,ss were 115% for deutetrabenazine and 95% for deuterated total (α+β)-HTBZ; and the GMR for Cmax,ss for deutetrabenazine was 95%. Relative bioavailability was assessed for Cmax,ss of the active metabolites; the GMR was 78% for total (α+β)-HTBZ. At steady state, deutetrabenazine administered as the once-daily formulation was bioequivalent to the twice-daily formulation for both AUC and Cmax, and the active metabolites were bioequivalent with regard to AUC0-24 h,ss .

Real-World Experience With Deutetrabenazine for Huntington Disease Chorea

Huntington disease (HD) is a hereditary neurodegenerative disorder with a hallmark feature of chorea. While no disease-modifying therapies currently exist for HD, symptomatic treatment of HD-associated chorea includes US Food and Drug Administration-approved vesicular monoamine transporter type 2 inhibitors-tetrabenazine and deutetrabenazine. Deutetrabenazine was more recently approved (2017), and while structurally similar to tetrabenazine, deutetrabenazine has a unique pharmacokinetic profile that allows for a longer half-life, reduced plasma fluctuations, and less frequent dosing. In pivotal trials, deutetrabenazine seemed to have an improved safety and tolerability profile over tetrabenazine but real-world data to confirm this are lacking. Here, we evaluate our real-world clinical experience with deutetrabenazine for HD-associated chorea. We performed a retrospective chart review of all patients with HD who initiated treatment with deutetrabenazine from January 2017 to May 2019 at the University of Alabama at Birmingham. Total maximal chorea scores, patient-reported subjective efficacy, dosing information, and subjective reports of adverse events (AEs) were abstracted for each patient. Our review included 58 patients with a mean length of treatment of 476.4 days. In the reviewed time period, the mean treatment difference in total maximal chorea scores was 4.4. The combined total rate of occurrence of any AEs was relatively low, at 32.8%, and the most commonly reported AEs were sedation (15.5%), insomnia (6.9%), and diarrhea (3.4%). Our real-world data support current literature indicating that deutetrabenazine is an effective and well-tolerated treatment for HD-associated chorea. Further studies repeating this on a larger scale, across a greater geography and practice pattern, are needed.

Exploring real-world symptom impact and improvement in well-being domains for tardive dyskinesia in VMAT2 inhibitor-treated patients via clinician survey and chart review

Introduction

Two vesicular monoamine transporter 2 (VMAT2) inhibitors are approved in the United States (US) for the treatment of tardive dyskinesia (TD). There is a paucity of information on the impact of VMAT2 inhibitor treatment on patient social and physical well-being. The study objective was to elucidate clinician-reported improvement in symptoms and any noticeable changes in social or physical well-being in patients receiving VMAT2 inhibitors.

Methods

A web-based survey was offered to physicians, nurse practitioners, and physician assistants based in the US who prescribed valbenazine for TD within the past 24 months. Clinicians reported data from the charts of patients who met the inclusion criteria and were allowed to recall missing information.

Results

Respondents included 163 clinicians who reviewed charts of 601 VMAT2-treated patients with TD: 47% had TD symptoms in ≥2 body regions, with the most common being in the head or face and upper extremities. Prior to treatment, 93% of patients showed impairment in ≥1 social domain, and 88% were impaired in ≥1 physical domain. Following treatment, among those with improvement in TD symptoms (n = 540), 80% to 95% showed improvement in social domains, 90% to 95% showed improvement in physical domains, and 73% showed improvement in their primary psychiatric condition.

Discussion

In VMAT2-treated patients with TD symptom improvement, clinicians reported concomitant improvement in psychiatric disorder symptoms and in social and physical well-being. Regular assessment of TD impact on these types of domains should occur simultaneously with movement disorder ratings when evaluating the value of VMAT2 inhibitor therapy.

Predictors of persistence and adherence to deutetrabenazine among patients with Huntington disease or tardive dyskinesia

Introduction

Deutetrabenazine is approved for treatment of Huntington disease (HD)-related chorea and tardive dyskinesia (TD) in adults. Factors associated with deutetrabenazine persistence and adherence are not well understood.

Methods

Claims data from the Symphony Health Solutions Integrated Dataverse (2017-2019) were analyzed to identify real-world predictors of deutetrabenazine persistence and adherence in adults with HD or TD in the United States. Predictive models for persistence and adherence that considered patient demographics, payer type, comorbidities, treatment history, and health care resource use were developed.

Results

In HD, use of anticonvulsants (HR = 2.00 [95% CI = 1.03, 3.85]; P < .05), lipid-lowering agents (2.22 [1.03, 4.76]; P < .05), and Medicaid versus Medicare insurance (2.27 [1.03, 5.00]; P < .05) predicted persistence, whereas only comorbid anxiety disorders predicted discontinuation (0.46 [0.23, 0.93]; P < .05). Of these patients, 62.5% were adherent at 6 months. Use of ≤2 treatments for chronic diseases (OR = 0.18 [95% CI = 0.04, 0.81]; P < .05) and Medicaid versus Medicare insurance (0.27 [0.09, 0.75]; P < .05) was associated with lower odds of adherence. In TD, use of lipid-lowering agents (HR = 4.76 [95% CI = 1.02, 20.00]; P < .05) predicted persistence, while comorbid schizoaffective disorder and/or schizophrenia (0.16 [0.14, 0.69]; P < .05) and sleep-wake disorders (0.18 [0.04, 0.82]; P < .05) predicted discontinuation. Of these patients, 46.7% were adherent at 6 months. Comorbid schizoaffective disorder and/or schizophrenia was associated with lower odds of adherence (OR = 0.26 [0.07, 0.91]; P < .05).

Discussion

Identifying factors predictive of discontinuation and/or nonadherence to deutetrabenazine may facilitate the development of personalized support programs that seek to improve outcomes in patients with HD or TD.

Safety and Efficacy of Long-Term Deutetrabenazine Use in Children and Adolescents with Tics Associated with Tourette Syndrome: An Open-Label Extension Study

Background

Tourette syndrome (TS) is a neurodevelopmental disorder characterized by motor and phonic tics.

Objective

To assess the safety and efficacy of deutetrabenazine (Teva Neuroscience, Inc, Parsippany, NJ), a vesicular monoamine transporter 2 inhibitor, in children and adolescents with TS.

Methods

Alternatives for Reducing Tics in TS (ARTISTS) open-label extension (OLE) (NCT03567291) was a 54-week, global, phase 3, open-label extension study of deutetrabenazine (6-48 mg daily) conducted May 28, 2018 to April 3, 2020 with a 2-week randomized withdrawal period. Participants (6-16 years of age) had TS and active tics causing distress or impairment. Safety (primary outcome) was assessed by treatment-emergent adverse events (TEAEs) and clinical laboratory testing. Efficacy was measured by the Yale Global Tic Severity Scale-Total Tic Score (YGTSS-TTS).

Results

The intent-to-treat population (228 participants; mean age, 12.0 years; 79.8% male; 86.4% white) had a median (range) duration of exposure of 28.4 (0.3-52.9) weeks. Of 227 participants in the safety analysis, 161 (70.9%) reported ≥1 TEAE (exposure-adjusted incidence rate, 2.77/patient-year), of which 95 (41.9%) were treatment related. The most frequently reported TEAEs were headaches, somnolence, nasopharyngitis, weight increases, and anxiety. No additional safety signals were observed. Worsening of YGTSS-TTS after the 2-week randomized withdrawal was not statistically significant (least squares mean difference, -0.4; P = 0.78). Several exploratory measures showed sustained improvement throughout the treatment periods.

Conclusions

In this long-term, open-label trial, deutetrabenazine was well tolerated with low frequency of TEAEs. There was no significant difference in tics between treatment arms during the 2-week randomized withdrawal period, however, descriptive statistics and comparison with baseline showed a numeric improvement in tics, quality of life, and other measures.

Evaluation of Deutetrabenazine's Potential to Delay Cardiac Repolarization Using Concentration-QTc Analysis

Deutetrabenazine (Austedo) is indicated in adults for chorea associated with Huntington disease and tardive dyskinesia. Escalating deutetrabenazine doses were administered to healthy volunteers who were cytochrome P450 2D6 extensive/intermediate metabolizers (EMs) or poor metabolizers (PMs) to determine pharmacokinetic exposure of parent drug and active metabolites (α-dihydrotetrabenazine [α-HTBZ] and β-dihydrotetrabenazine [β-HTBZ]), and collect corresponding electrocardiograms (ECGs) for evaluation of the cardiodynamic effect using concentration-QTc (C-QTc) modeling. Participants (12 EMs, 24 PMs) received placebo or single doses of deutetrabenazine (24, 48, and 72 mg) to achieve plasma concentrations exceeding therapeutic range in both cohorts. Pharmacokinetic samples were obtained over 72 hours after dosing and were time matched with 12-lead ECGs extracted from continuous ECG recordings. C-QTc analysis, using linear mixed-effects modeling and model selection procedure, characterized the relationship between plasma concentrations of deutetrabenazine, deuterated α-HTBZ and β-HTBZ, and the change from baseline in QT interval corrected using Fridericia's formula. Deutetrabenazine exhibited linear kinetics, and a C-QTc model with deuterated α-HTBZ and β-HTBZ was selected to best describe the C-QTc relationship in pooled EM and PM data. This model predicted a placebo-corrected Fridericia corrected QT interval prolongation higher than 10 milliseconds can be excluded at concentrations associated with the maximum recommended doses in both populations. Adverse events increased with higher exposure as reflected by the higher event number in the PM cohort receiving 48 and 72 mg doses. No subject discontinued due to cardiac-related adverse events and no clinically relevant ECG findings were reported. Thus, this study found that deutetrabenazine does not have a clinically relevant effect on QT prolongation at maximum recommended doses in either cytochrome P450 2D6 EMs or PMs.

Long-Term Deutetrabenazine Treatment for Tardive Dyskinesia Is Associated With Sustained Benefits and Safety: A 3-Year, Open-Label Extension Study

Background

Deutetrabenazine is a vesicular monoamine transporter 2 inhibitor approved for the treatment of tardive dyskinesia (TD) in adults. In two 12-week pivotal studies, deutetrabenazine demonstrated statistically significant improvements in Abnormal Involuntary Movement Scale (AIMS) scores, with favorable safety/tolerability in TD patients. This study reports long-term efficacy and safety of deutetrabenazine in a 3-year, single-arm, open-label extension (OLE) study.

Methods

Patients who completed the pivotal studies could enroll in this single-arm OLE study, titrating up to 48 mg/day based on dyskinesia control and tolerability. Efficacy was assessed based on change from baseline in total motor AIMS score, Clinical Global Impression of Change (CGIC) and Patient Global Impression of Change (PGIC), and quality of life (QOL) assessments. Safety evaluation included adverse event (AE) incidence, reported using exposure-adjusted incidence rates, and safety scales.

Results

343 patients enrolled in the study (6 patients were excluded). At Week 145 (mean dose: 39.4 ± 0.83 mg/day), mean ± SE change from baseline in total motor AIMS score was −6.6 ± 0.37 and 67% of patients achieved ≥50% improvement in total motor AIMS score. Based on CGIC and PGIC, 73% and 63% of patients achieved treatment success, respectively. QOL improvements were also observed. Deutetrabenazine was generally well tolerated, with low rates of mild-to-moderate AEs and no new safety signals; most safety scales remained unchanged over time.

Conclusions

Long-term deutetrabenazine treatment was associated with sustained improvement in AIMS scores, indicative of clinically meaningful long-term benefit, and was generally well tolerated. Results suggest deutetrabenazine may provide increasing benefit over time without increases in dose.

Benign Presentation Following Massive Deutetrabenazine Overdose

Deutetrabenazine (DTBZ) (Austedo®) is a novel vesicular monoamine transporter 2 (VMAT2) inhibitor, which acts by blocking dopamine release and other monoamines from neuronal vesicles. Although this drug is considered the first-line treatment for tardive dyskinesia (TD), VMAT2 inhibition has also been shown to improve patients’ symptoms with Huntington’s disease-induced chorea. We present the case of a 59-year-old woman with a history of TD, who presented to the emergency department following massive DTBZ ingestion. The relative paucity of other overdose symptoms further supports the manufacturer’s claims of a low side effect profile for this drug in overdose. Although DTBZ demonstrates an excellent safety profile, emergency physicians should be aware of the potential side effect of DTBZ overdose, in addition to other known side effects of this novel drug.

Cost-effectiveness of valbenazine compared with deutetrabenazine for the treatment of tardive dyskinesia

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.

Case Report: Deutetrabenazine as an Adjunctive Treatment for Stuttering

Childhood-Onset Fluency Disorder (Stuttering) is a neurodevelopmental disorder in which disturbances occur in the normal fluency and time patterning of speech. While the dopamine system has been well-described in its neurophysiology, there currently is no FDA-approved treatment for stuttering. Second-generation antipsychotics, which have been effective in the treatment of schizophrenia and bipolar disorder, act as dopamine D-2 receptor antagonists at the postsynaptic neuron and have been shown to reduce the symptoms of stuttering. However, the D-2 receptor antagonist and partial agonist agents carry the potential for metabolic side effects and can potentially lead to movement disorders. Deutetrabenazine, a VMAT-2 inhibitor indicated to treat hyperkinetic movement disorders, is a potential candidate in the treatment of stuttering, based on its mechanism of action in decreasing dopamine activity while not carrying the risk of metabolic adverse events.

Deutetrabenazine for treatment of involuntary movements in patients with tardive dyskinesia

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.

Valbenazine and deutetrabenazine: Vesicular monoamine transporter 2 inhibitors for tardive dyskinesia

PURPOSE

The purpose of this review is to summarize the current evidence for valbenazine and deutetrabenazine use for the treatment of tardive dyskinesia (TD).

SUMMARY

A literature search was conducted to gather relevant data regarding the use of valbenazine and deutetrabenazine for TD management. PubMed, MEDLINE, and ClinicalTrials.gov were searched using the following keywords and MeSH terms: valbenazine, deutetrabenazine, tardive dyskinesia, VMAT2 inhibitors, and vesicular monoamine transporter 2 inhibitors. Randomized, double-blind, placebo-controlled trials and meta-analyses published in English from April 2015 to August 2019 were included. Valbenazine 40-80 mg and deutetrabenazine 12-36 mg per day have been evaluated for the treatment of TD. Abnormal Involuntary Movement Scale (AIMS) scores decline similarly (by 2-5 points) with use of either agent. AIMS response rates, defined by a 50% decline in symptoms, range from 33% to 50%. Both agents are well tolerated, with somnolence and akathisia reported most frequently (at low rates). Agent selection may be guided by manufacturer labeling recommendations for special populations and cost considerations.

CONCLUSIONS

Valbenazine and deutetrabenazine were demonstrated to be effective in decreasing AIMS scores and were well tolerated in randomized controlled trials. These treatments may be considered as a next-line option when traditional strategies are not feasible or are ineffective. Head-to-head studies are warranted to decipher if either agent is preferable in terms of efficacy or tolerability.

Pharmacokinetics of Deutetrabenazine and Tetrabenazine: Dose Proportionality and Food Effect

Deutetrabenazine (Austedo, Teva), an approved treatment of chorea in Huntington's disease and tardive dyskinesia in adult patients, is a rationally designed deuterated form of tetrabenazine. Two studies assessed the pharmacokinetics and safety of deutetrabenazine compared with tetrabenazine, and the effects of food on absorption of the deuterated active metabolites, α‐dihydrotetrabenazine (α‐HTBZ) and β‐dihydrotetrabenazine (β‐HTBZ). One study was an open‐label 2‐part study in healthy volunteers; the first part included a crossover single dose of two 15 mg candidate deutetrabenazine formulations in fed and fasted states compared with tetrabenazine 25 mg in the fasted state, and the second part included single and repeated dosing of the commercial formulation of deutetrabenazine (7.5, 15, and 22.5 mg) compared with tetrabenazine 25 mg. The second study was an open‐label 5‐way crossover study in healthy volunteers (n = 32) to evaluate relative bioavailability of 4 dose levels of the commercial formulation of deutetrabenazine (6, 12, 18, and 24 mg) with a standard meal and 18 mg with a high‐fat meal. Both studies confirmed longer half‐lives for active metabolites and lower peak‐to‐trough fluctuations for the sum of the metabolites (total [α+β]‐HTBZ) following deutetrabenazine compared with tetrabenazine (3‐ to 4‐fold and 11‐fold, respectively) in steady‐state conditions. Deutetrabenazine doses estimated to provide total (α+β)‐HTBZ exposure comparable to tetrabenazine 25 mg were 11.4‐13.2 mg. Food had no effect on exposure to total (α+β)‐HTBZ, as measured by AUC. Although the total (α+β)‐HTBZ C_max of deutetrabenazine was increased by ≈50% in the presence of food, it remained lower than that of tetrabenazine.

Long-term safety and efficacy of deutetrabenazine for the treatment of tardive dyskinesia

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.

Deutetrabenazine for tardive dyskinesia and chorea associated with Huntington's disease: a review of clinical trial data

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.

Role of Vesicular Monoamine Transporter 2 Inhibitors in Tardive Dyskinesia Management

Tardive dyskinesia (TD) is a distressing and disabling movement disorder that occurs with the use of chronic neuroleptic medications. TD is defined as involuntary athetoid or choreiform movements of head, trunk or limbs. Tongue, lower face, jaw, and extremities are commonly involved but pharyngeal, diaphragmatic, or truncal muscles are also sometimes involved affecting breathing, swallowing, speech, posture, gait, and mobility of an individual.

TD is a debilitating movement disorder that requires timely intervention. Subtle tongue movements, tic-like facial movements or increased blink frequency could be some of the initial manifestations of TD. Our article is focused on the new advents in treating TD, their efficacy, and tolerability with emphasizing their side effect profile. The implication of a genetic marker vesicular monoamine transporter 2 (VMAT2), helped in investigating VMAT2 inhibitors for alleviating TD. Among the modalities tested, only VMAT2 inhibitors reported efficacy. However, the outcome of long-term use and its side effect profile can only be determined with longer studies utilizing large set data. More clinical trials are required to explore individual drug efficacy and their long-term adverse effects.

We aim to provide an overview of TD management, illustrating the priority of VMAT2 inhibitors and to determine the importance of selecting an optimal medication. A search through PubMed with terms "Tardive dyskinesia" and "VMAT2 inhibitors" was carried out. Several treatment modalities were tested to control the symptoms of TD with limited benefit. However, VMAT2 inhibitors showed improvement in the Abnormal Involuntary Movement Scale (AIMS) rating scale for TD. Valbenazine and deutetrabenazine (d-TBZ) were recently approved by the Food and Drug Administration (FDA) for treating TD in adults.

Deutetrabenazine in the treatment of tardive dyskinesia

Tardive dyskinesia is a common movement disorder in the population of patients taking dopamine receptor blocking agents, such as antipsychotics and certain antiemetics, which likely lead to D2-receptor upregulation and hypersensitization. Efficacious and well-tolerated treatments are now available to reduce symptoms. Deutetrabenazine, a reversible inhibitor of vesicular monoamine transporter 2, was US FDA-approved for treatment of tardive dyskinesia in 2017. Two pivotal clinical trials, Aim to Reduce Movements in Tardive Dyskinesia (ARM-TD) and Addressing Involuntary Movements in Tardive Dyskinesia (AIM-TD), provide evidence that deutetrabenazine dosed 24-48 mg/day effectively controlled involuntary movements according to rating scales. Adverse events that occurred more frequently in the deutetrabenazine group (rate >2%) compared with placebo were nasopharyngitis and insomnia. Interim results of a long-term open-label study show continued efficacy and good tolerability, even in combination with baseline dopamine receptor blocking agents.

Overcoming barriers to effective management of tardive dyskinesia

Tardive dyskinesia (TD) is a heterogeneous syndrome of involuntary hyperkinetic movements that is often persistent and occurs belatedly during treatment with antipsychotics. Recent approval of two dopamine-depleting analogs of tetrabenazine based on randomized controlled trials offers an evidence-based therapeutic approach to TD for the first time. These agents are optimally used within the context of a comprehensive approach to patient management that includes a practical screening and monitoring program, sensitive and specific criteria for the diagnosis of TD, awareness of the severity and impact of the disorder, informed discussions with patients and caregivers, and a rational basis for prescribing decisions about continued antipsychotic and adjunctive agents. Areas of limited or inconclusive data, bias and misunderstandings about key aspects, and neglect of training about TD in recent years contribute to barriers in providing effective care and promoting patient safety.

A systematic review on treatment of tardive dyskinesia with valbenazine and deutetrabenazine

Recent reports state that the prevalence of tardive dyskinesia (TD) is 32% with typical antipsychotics, and 13% with atypical antipsychotics. Current evidence-based recommendations determine an unmet need for efficacious treatment of TD. This systematic review was planned to update the evidence for TD treatment, comparing two vesicular monoamine transporter 2 (VMAT2) inhibitors, deutetrabenazine (DBZ), and valbenazine (VBZ). Of 75 PubMed search results, 11 studies met the review criteria. Efficacy and tolerability were demonstrated in a series of randomized, placebo-controlled clinical trials in our review study, and the Abnormal Involuntary Movement Scale response of ⩾50% reduction in score was robust for VBZ 80 mg/day in short-term and long-term studies. On the contrary, DBZ was equally efficacious at 12 mg twice daily, but additional information about long-term efficacy and persistence of effect is needed.

Valbenazine and Deutetrabenazine for Tardive Dyskinesia

Tardive dyskinesia (TD) is a medication-induced permanent movement disorder with no United States Food and Drug Administration (FDA)-approved treatments prior to 2017. Although TD is medication-induced, patients who have responded well to antipsychotics might not be candidates for dose reduction or discontinuation due to a risk of psychiatric decompensation. Valbenazine and deutetrabenazine were recently approved by the FDA for the treatment of TD. They offer a unique mechanism of action by inhibiting vesicular monoamine transporter type 2. The objective of this review is to discuss the efficacy, tolerability, dosing, drug interactions, and precautions for valbenazine and deutetrabenazine.

Treatment of tardive dyskinesia with VMAT-2 inhibitors: a systematic review and meta-analysis of randomized controlled trials

Aim

The aim of this study was to summarize the characteristics, efficacy, and safety of vesicular monoamine transporter-2 (VMAT-2) inhibitors for treating tardive dyskinesia (TD).

Materials and methods

We conducted a literature search in PubMed, Cochrane Database, and ClinicalTrials.gov, screening for systematic reviews, meta-analyses or double-blind, randomized, placebo-controlled trials (DBRPCTs) reporting efficacy or safety data of VMAT-2 inhibitors (tetrabenazine, deutetrabenazine, and valbenazine) in patients with TD. A random effects meta-analysis of efficacy and safety data from DBRPCTs was performed.

Results

Two acute, 12-week DBRPCTs with deutetrabenazine 12–48 mg/day (n=413) and 4 acute, 4–6-week double-blind trials with valbenazine 12.5–100 mg/day (n=488) were meta-analyzable, without meta-analyzable, high-quality data for tetrabenazine. Regarding reduction in total Abnormal Involuntary Movement Scale (AIMS) scores (primary outcome), both deutetrabenazine (k=2, n=413, standardized mean difference [SMD] =−0.40, 95% confidence interval [CI] =−0.19, −0.62, p<0.001; weighted mean difference (WMD) =−1.44, 95% CI =−0.67, −2.19, p<0.001) and valbenazine (k=4, n=421, SMD =−0.58, 95% CI =−0.26, −0.91, p<0.001; WMD =−2.07, 95% CI =−1.08, −3.05, p<0.001) significantly outperformed placebo. Results were confirmed regarding responder rates (≥50% AIMS total score reduction; deutetrabenazine: risk ratio [RR] =2.13, 95% CI =1.10, 4.12, p=0.024, number-needed-to-treat [NNT] =7, 95% CI =3, 333, p=0.046; valbenazine: RR =3.05, 95% CI =1.81, 5.11, p<0.001, NNT =4, 95% CI =3, 6, p<0.001). Less consistent results emerged from patient-rated global impression-based response (p=0.15) and clinical global impression for deutetrabenazine (p=0.088), and for clinical global impression change for valbenazine (p=0.67). In an open-label extension (OLE) study of deutetrabenazine (≤54 weeks) and a dose-blinded valbenazine study (≤48 weeks), responder rates increased over time. With valbenazine, discontinuation effects were studied, showing TD symptom recurrence towards baseline severity levels within 4 weeks after valbenazine withdrawal. No increased cumulative or specific adverse (AEs) events versus placebo (acute trials) in extension versus acute trial data were observed.

Conclusion

The 2 VMAT-2 inhibitors, valbenazine and deutetrabenazine, are effective in treating TD, both acutely and long-term, without concerns about increased risk of depression or suicide in the TD population. No head-to-head comparison among VMAT-2 inhibitors and no high-quality, meta-analyzable data are available for tetrabenazine in patients with TD.

Update on the Pharmacological Treatment of Tics with Dopamine-Modulating Agents

More than 40 years of research and clinical practice have proven the effectiveness of dopamine receptor antagonists in the pharmacological treatment of tics. A blockade of the striatal dopamine-D2 receptors is mainly responsible for their tic-reducing effect. A broad spectrum of dopamine-modulating agents, such as typical and atypical antipsychotics, but also dopamine receptor agonists are used with an immanent discord between experts about which of them should be considered as first choice. The present Review outlines the state of the art on pharmacological treatment of tics with dopamine-modulating agents by giving an systematic overview of studies on their effectiveness and a critical discussion of their specific adverse effects. It is considered as an update of a previous review of our research group published in 2013. The Review closes with a description of the current resulting treatment recommendations including the results of a first published revised survey on European expert's prescription preferences. Based on the enormously growing evidence on its effectiveness and safety, aripiprazole currently seems to be the most promising agent in the pharmacological treatment of tics. Furthermore, benzamides (especially tiapride), which are commonly used in Europe, have proven their excellent effectiveness-tolerability profile over decades in clinical practice and are therefore also highly recommended for the treatment of tics. Nevertheless, pharmacological treatment of tics remains an indiviual choice depending on each patient's own specific needs.

VMAT2 Inhibitors for Tardive Dyskinesia-Practice Implications

Tardive dyskinesia is a potentially irreversible, debilitating, hyperkinetic movement disorder that can result from dopamine receptor antagonists. Prompt recognition and resolution of symptoms are instrumental in preventing disease irreversibility, though current treatment options have fallen short of robust, effective, and long-term symptom control. In April 2017, the Food and Drug Administration (FDA) approved 2 new vesicular monoamine transporter 2 (VMAT2) inhibitors, deutetrabenazine and valbenazine, for chorea related to Huntington's disease and tardive dyskinesia, respectively. These agents were pharmacologically modified from tetrabenazine, a VMAT2 inhibitor used off-label in the treatment of tardive dyskinesia. Despite FDA-labeled indications of deutetrabenazine and valbenazine, each agent was explored as a treatment option for those with tardive dyskinesia. In this study, the pharmacologic modifications of the 2 new VMAT2 inhibitors are described, with detailed explanation as to how these may impact clinical practice. The associated case series, observational studies, and clinical trials exploring their use in the treatment of tardive dyskinesia are reported with expert opinion on practice implication.

Review of deutetrabenazine: a novel treatment for chorea associated with Huntington's disease

Deutetrabenazine was recently approved for the treatment of chorea in Huntington’s disease (HD) and is the first deuterated medication that has been US Food and Drug Administration (FDA)-approved for therapeutic use. In this article, we review deutetrabenazine’s drug design, pharmacokinetics, drug interactions, efficacy, adverse events, comparison with tetrabenazine, dosage, and administration. Deutetrabenazine is a deuterated form of tetrabenazine and is a vesicular monoamine transporter 2 (VMAT2) inhibitor. The substitution of deuterium for hydrogen at key positions in the tetrabenazine molecule allows a longer drug half-life and less frequent daily dosing. Deutetrabenazine is administered twice daily up to a maximum daily dose of 48 mg, which corresponds to a similar daily dose of 100 mg of tetrabenazine. In a Phase III clinical trial (First-HD), there was a statistically significant improvement of chorea in HD subjects, as well as improvements in global impression of change as assessed by both patients and clinicians. This improvement was seen without significant adverse effects as the overall tolerability profile of deutetrabenazine was similar to placebo. Somnolence was the most commonly reported symptom in the deutetrabenazine group. In a study where subjects converted from tetrabenazine to deutetrabenazine in an open-label fashion (ARC-HD) and indirect comparison studies between tetrabenazine and deutetrabenazine, there is a suggestion that while efficacy for chorea is similar, the data may slightly favor tetrabenazine, but adverse effects and tolerability strongly favor deutetrabenazine. These data have not been replicated in true head-to-head studies. Current evidence supports that deutetrabenazine is an effective therapeutic treatment option for chorea in HD and may provide a more favorable adverse effect profile than tetrabenazine. However, more data are needed, particularly in the form of head-to-head studies between deutetrabenazine and other treatment options as well as longer term clinical experience with deutetrabenazine.

Treatment options for chorea

INTRODUCTION

Chorea is defined as jerk-like movements that move randomly from one body part to another. It is due to a variety of disorders and although current symptomatic therapy is quite effective there are few etiology- or pathogenesis-targeted therapies. The aim of this review is to summarize our own experience and published evidence in the treatment of chorea. Areas covered: After evaluating current guidelines and clinical practices for chorea of all etiologies, PubMed was searched for the most recent clinical trials and reviews using the term 'chorea' cross referenced with specific drug names. Expert commentary: Inhibitors of presynaptic vesicular monoamine transporter type 2 (VMAT2) that cause striatal dopamine depletion, such as tetrabenazine, deutetrabenazine, and valbenazine, are considered the treatment of choice in patients with chorea. Some clinicians also use dopamine receptor blockers (e.g. antipsychotics) and other drugs, including anti-epileptics and anti-glutamatargics. 'Dopamine stabilizers' such as pridopidine and other experimental drugs are currently being investigated in the treatment of chorea. Deep brain stimulation is usually reserved for patients with disabling chorea despite optimal medical therapy.

Tetrabenazine Versus Deutetrabenazine for Huntington's Disease: Twins or Distant Cousins?

Background

Tetrabenazine is the only US Food and Drug Administration‐approved drug for Huntington's disease, and deutetrabenazine was recently tested against placebo. A switching‐trial from tetrabenazine to deutetrabenazine is underway, but no head‐to‐head, blinded, randomized controlled trial is planned. Using meta‐analytical methodology, the authors compared these molecules.

Methods

RCTs comparing tetrabenazine or deutetrabenazine with placebo in Huntington's disease were searched. The authors assessed the Cochrane risk‐of‐bias tool, calculated indirect treatment comparisons, and applied the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework.

Results

The evidence network for this report comprised 1 tetrabenazine trial and 1 deutetrabenazine trial, both against placebo. Risk of bias was moderate in both. Participants in the tetrabenazine and deutetrabenazine trials did not differ significantly on motor scores or adverse events. Depression and somnolence scales significantly favored deutetrabenazine.

Conclusion

There is low‐quality evidence that tetrabenazine and deutetrabenazine do not differ in efficacy or safety. It is important to note that these results are likely to remain the only head‐to‐head comparison between these 2 compounds in Huntington's disease.

Emerging pharmacological therapies in schizophrenia: what's new, what's different, what's next?

There are several new and emerging medication interventions for both the acute and maintenance treatment phases of schizophrenia. Recently approved are 2 new dopamine receptor partial agonists, brexpiprazole and cariprazine, as well as 2 new long-acting injectable antipsychotic formulations, aripiprazole lauroxil and 3-month paliperidone palmitate. Although differences in efficacy compared to other available choices are not expected, the new oral options offer different tolerability profiles that may be attractive for individual patients who have had difficulties with older medications. The new long-acting injectable options provide additional flexibility in terms of increasing the time interval between injections. In Phase III of clinical development is a novel antipsychotic, lumateperone (ITI-007), that appears to have little in the way of significant adverse effects. Deutetrabenazine and valbenazine are agents in Phase III for the treatment of tardive dyskinesia, a condition that can be found among persons receiving chronic antipsychotic therapy. On the horizon are additional injectable formulations of familiar antipsychotics, aripiprazole and risperidone, that may be more convenient than what is presently available.

Deutetrabenazine in Tics Associated with Tourette Syndrome

Background

Deutetrabenazine, an inhibitor of vesicular monoamine transporter type 2 (VMAT2) depletes presynaptic dopamine and is useful in the treatment of hyperkinetic movement disorders. This study explored the safety, tolerability, and preliminary efficacy of deutetrabenazine in adolescents with moderate-to-severe tics associated with Tourette syndrome (TS).

Methods

In this open-label study of 12–18-year-old patients with TS-related tics, deutetrabenazine was titrated up to 36 mg/day over 6 weeks to adequately suppress tics without bothersome adverse effects (AEs), followed by maintenance at optimal dose for 2 weeks. An independent blinded rater assessed tic severity using the Yale Global Tic Severity Scale (YGTSS), which was the primary outcome measure. Secondary outcome measures included the TS Clinical Global Impression (TS-CGI) and TS Patient Global Impression of Change (TS-PGIC).

Results

Twenty-three enrolled patients received deutetrabenazine and had at least 1 post-baseline YGTSS assessment. The mean (SD [standard deviation]) baseline YGTSS Total Tic Severity Score (TTS) was 31.6 (7.9) and had decreased by 11.6 (8.2) points at week 8, a 37.6% reduction in tic severity (p<0.0001). The TS-CGI score improved by 1.2 (0.81) points (p<0.0001) and the TS-PGIC results at week 8 indicated that 76% of patients were much improved or very much improved compared with baseline. The mean (SD) daily deutetrabenazine dose at week 8 was 32.1 (6.6) mg (range 18–36 mg). One week after withdrawal of deutetrabenazine, the TTS scores increased by 5.6 (8.4) points, providing confirmation of the drug effect. No serious or severe adverse events were reported.

Discussion

The results of this open-label 8-week study suggest that deutetrabenazine is safe and associated with improvement in tic severity in adolescents with TS and troublesome tics.