Treatment of Tardive Dyskinesia: A General Overview with Focus on the Vesicular Monoamine Transporter 2 Inhibitors

Profiling deutetrabenazine extended-release tablets for tardive dyskinesia and chorea associated with Huntington's disease

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.

An Unexpected Phenomenon: A Case of Citalopram-Induced Dyskinesia

Dyskinetic movements are characterized as hyperkinetic, repetitive movements of the extremities, facial, and oral musculature, most associated with prolonged dopamine D2 receptor blockade. In rare instances, dyskinetic movements can be brought on by selective serotonin reuptake inhibitor (SSRI) usage via an indirect D2 blockade mechanism, mimicking the D2 blockade observed with dopamine receptor blocking agents (DRBAs), such as in first-generation antipsychotics. This mimicked D2 blockade by SSRIs is said to be due to increased tonic inhibition by serotonin on dopaminergic neurons in the dopaminergic pathways of the brain, specifically the nigrostriatal pathway. In this case report, we look at a patient with a history of cerebral palsy who developed acute dyskinetic movements after short-term citalopram usage. The objective is to bring attention to the possible extrapyramidal side effects (EPS) of SSRI usage.

The Outcome of Antipsychotics-induced Tardive Syndromes: A Ten-year Follow-up Study

Objective

Tardive syndrome (TS) is an umbrella term used to describe a group of abnormal movement disorders caused by chronic exposure to dopamine receptor blocking agents. Few follow-up studies have been performed on the outcome of TS in patients using antipsychotics. The purpose of our study was to investigate the prevalence, incidence, remission rate, and factors associated with remission in patients using antipsychotics.

Methods

This retrospective cohort study consisted of 123 patients who received continuous treatment of antipsychotics in a medical center in Taiwan, from April 1, 2011 to May 31, 2021. We assessed the demographic and clinical characteristics, prevalence, incidence, remission rate, and factors associated with remission in patients using antipsychotics. TS remission was defined as a Visual Analogue Scale score ≤ 3.

Results

Of the 92 patients who completed the 10-year follow-up, 39 (42.4%) were found to have at least one episode of TS, with tardive dyskinesia (TD) being the most prevalent subtype (51.3%). With regard to concurrent physical illness, a history of extrapyramidal symptoms were significant risk factors for TS. During the 10-year follow-up period, the remission rate of TS was 74.3%. The use of antioxidants including vitamin B6 and piracetam was related to the remission of TS. Patients with tardive dystonia had a higher remission rate (87.5%) compared to TD (70%).

Conclusion

Our study suggests that TS may be a treatable condition, and the key to a better outcome is early detection and prompt intervention, including closely monitoring antipsychotics-related TS symptoms and using antioxidants.

Effective treatment of choreaballism due to an MT-CYB variant with haloperidol, tetrabenazine, and antioxidants

Hypokinetic and hyperkinetic movement disorders are a common phenotypic feature of mitochondrial disorders. Choreaballism has been reported particularly in patients with mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes syndrome and in maternally inherited diabetes and deafness syndrome. The pathophysiological basis of movement disorders in mitochondrial disorders is the involvement of the basal ganglia or the midbrain. Haloperidol and mitochondrial cocktails have proven beneficial in some of these cases. Here we present another patient with mitochondrial choreaballism who benefited significantly from symptomatic therapy. The patient is a 14-year-old male with a history of hypoacusis, ptosis, and focal tonic-clonic seizures of the upper/lower limbs on either side since childhood. Since this time he has also developed occasional, abnormal involuntary limb movements, choreaballism, facial grimacing, carpopedal spasms, and abnormal lip sensations. He was diagnosed with a non-syndromic mitochondrial disorder after detection of the variant m.15043G > A in MT-CYB. Seizures have been successfully treated with lamotrigine. Hypocalcemia was treated with intravenous calcium. For hypoparathyroidism calcitriol was given. Choreaballism was treated with haloperidol and tetrabenazine. In addition, he received coenzyme Q10, L-carnitine, thiamine, riboflavin, alpha-lipoic acid, biotin, vitamin-C, vitamin-E, and creatine-monohydrate. With this therapy, the choreaballism disappeared completely. This case shows that mitochondrial disorders can manifest with cognitive impairment, seizures, movement disorder, hypoacusis, endocrinopathy, cardiomyopathy, neuropathy, and myopathy, that choreaballism can be a phenotypic feature of multisystem mitochondrial disorders, and that choreaballism favorably responds to haloperidol, tetrabenazine, and possibly to a cocktail of antioxidants, cofactors, and vitamins.

Minimization of Acid-Catalyzed Degradation in KinetiSol Processing through HPMCAS Neutralization

Hypromellose acetate succinate (HPMCAS) is an enteric polymer that has been successfully employed as a carrier in amorphous solid dispersions (ASDs). Deprotonation of succinic acid substituents at intestinal pH levels results in solubilization of the polymer. However, the acidic moieties responsible for favorable pH-dependent solubility can also result in incompatibilities between acid-sensitive drugs and HPMCAS. Solution-state conversion of the carboxylic acid substituents of enteric polymers into carboxylate salts to reduce acid-mediated drug degradation is a demonstrated effective strategy for generating ASDs in enteric polymers. This work aimed to extend the use of a pre-ionized enteric polymer to KinetiSol solvent-free processing to reduce acid- or base-mediated drug degradation during processing. Pre-ionization of HPMCAS was accomplished by reaction with a stoichiometric quantity of sodium carbonate (Na₂CO₃) delivered as a saturated aqueous solution. The resulting ionized polymer, HPMCAS-Na, was dried thoroughly before processing. Tetrabenazine (TBZ) was chosen as a model drug for its susceptibility to degradation via both acid- and base-catalyzed reaction mechanisms and for its tendency to form a single impurity by these mechanisms. The use of HPMCAS-Na in KinetiSol solid dispersions (KSDs) of TBZ resulted in a 6- to 8-fold reduction of the acid- and base-generated TBZ impurity compared with KSDs formulated with untreated HPMCAS.

Efficacy and safety of valbenazine in Japanese patients with tardive dyskinesia: A multicenter, randomized, double-blind, placebo-controlled study (J-KINECT)

AIM

Valbenazine is approved in the US for treatment of tardive dyskinesia (TD); however, efficacy/safety data in Asian populations are lacking. We assessed the efficacy/safety of valbenazine in Japanese patients.

METHODS

This phase II/III, multicenter, randomized, double-blind, placebo-controlled study (NCT03176771) included adult psychiatric patients with TD, who were randomly allocated to receive placebo or valbenazine (once-daily 40- or 80-mg) for a 6-week, double-blind period, after which the placebo group was switched to valbenazine for a 42-week extension. The primary endpoint was change from baseline in Abnormal Involuntary Movement Scale (AIMS) total score at Week 6; clinical global impression of improvement of TD (CGI-TD) was also assessed.

RESULTS

Of 256 patients, 86, 85, and 85 were allocated to the 40-mg valbenazine, 80-mg valbenazine, and placebo groups, respectively. Least-squares mean (95% confidence interval) change from baseline in AIMS score at Week 6 was -2.3 (-3.0 to -1.7) in the valbenazine 40-mg group, -3.7 (-4.4 to -3.0) in the 80-mg group, and -0.1 (-0.8 to 0.5) in the placebo group; both treatment groups showed statistically significant improvements vs. placebo. Patients switched to valbenazine at Week 6 showed similar improvements in AIMS scores, which were maintained to Week 48. Improvements in CGI-TD scores were observed for both treatment groups vs. placebo. Incidence of adverse events was highest in the 80-mg group; common events included nasopharyngitis, somnolence, schizophrenia worsening, hypersalivation, insomnia, and tremor.

CONCLUSION

The efficacy/safety profile of valbenazine was similar to that of previous clinical trials, supporting its use for TD treatment in Japanese patients.

Pathophysiology, prognosis and treatment of tardive dyskinesia

Tardive dyskinesia (TD), a movement disorder associated with antipsychotics, most frequently affects the lower face and jaw muscles, but can also affect walking, breathing and use of the hands and limbs. Knowledge of TD among physicians may be limited, and the pathophysiology of TD is poorly understood. We conducted this review to summarise the current knowledge surrounding the pathophysiology of TD and present recommendations for prevention and treatment based on a literature search and roundtable discussion attended by psychiatrists in Japan. It has been suggested that dopamine hypersensitivity, damaged gamma-aminobutyric acidergic neurons and/or increased production of reactive oxygen species may contribute to development of TD. Symptoms can profoundly affect everyday life; patients who develop TD have poorer prognoses, worse health-related quality of life, greater social withdrawal and higher mortality than patients without TD. Traditional treatment options include dietary supplements, although evidence for their effectiveness is low. Among pharmaceutical interventions, there is moderate evidence that switching to the second-generation antipsychotic clozapine, which has a lower affinity for dopamine D₂ receptors than other antipsychotics, may improve symptoms. Vesicular monoamine transporter 2 (VMAT-2) inhibitors, which oppose the increased dopaminergic activity associated with prolonged antipsychotic use by interfering with dopamine uptake and storage, have the strongest evidence for efficacy. VMAT-2 inhibitors are approved in the United States for the treatment of TD, and the first VMAT-2 inhibitor was approved in Japan for this indication in March 2022. Most guidelines recommend treating TD by first reducing the dose of antipsychotics or switching to clozapine or other second-generation antipsychotics, which have a lower association with TD than first-generation antipsychotics. We recommend focusing on prevention and monitoring for TD when prescribing antipsychotics, given that TD is often irreversible. Physicians should treat with antipsychotics only when necessary and at the lowest effective dose, and frequently monitor for TD symptoms.

PLAIN LANGUAGE SUMMARY

Plain Language Summary (In Japanese).

VISUAL SUMMARY

Visual Summary (In Japanese).

Biologically active metabolites in drug discovery

Biologically active metabolites are a valuable resource for development of drug candidates and lead structures for drug design. This digest highlights a selection of biologically active metabolites that have been used as new chemical entities for development or as lead structures for drug design.

Botulinum Neurotoxin Injections in Childhood Opisthotonus

Opisthotonus refers to abnormal axial extension and arching of the trunk produced by excessive contractions of the paraspinal muscles. In childhood, the abnormal posture is most often related to dystonia in the setting of hypoxic injury or a number of other acquired and genetic etiologies. The condition is often painful, interferes with ambulation and quality of life, and is challenging to treat. Therapeutic options include oral benzodiazepines, oral and intrathecal baclofen, botulinum neurotoxin injections, and deep brain stimulation. Management of opisthotonus within the pediatric population has not been systematically reviewed. Here, we describe a series of seven children who presented to our institution with opisthotonus in whom symptom relief was achieved following administration of botulinum neurotoxin injections.

Tardive Dyskinesia in Older Persons Taking Antipsychotics

Tardive dyskinesia (TD) is a hyperkinetic movement disorder caused by the use of dopamine receptor-blocking agents (DRBAs), a category of medications that includes first- and second-generation antipsychotics (APs) and agents such as metoclopramide that are used for the treatment of nausea and gastrointestinal dysmotility. While TD can affect people of all ages, older age is associated with increased risk of TD and also with the emergence of TD occurring after shorter treatment durations and lower dosages of DRBAs. TD is characterized by involuntary movements that include the face, limbs, and trunk, and is associated with increased comorbidities, social stigmatization, and impaired physical and mental health. Once present, TD tends to persist despite AP dose adjustment or discontinuation. Even with the use of US Food and Drug Administration (FDA)-approved medications for TD, symptoms may persist. Because the leading hypothesis for the pathophysiology of TD has been dysregulation of dopamine transmission due to treatment with DRBAs, APs that avoid postsynaptic dopamine receptor blockade may provide an alternative therapeutic approach for patients who require an AP. In this review, we discuss the risks, burdens, prevention, and management of TD, with a focus on older people.

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.

Synthesis of Tetrabenazine and Its Derivatives, Pursuing Efficiency and Selectivity

Tetrabenazine is a US Food and Drug Administration (FDA)-approved drug that exhibits a dopamine depleting effect and is used for the treatment of chorea in Huntington’s disease. Mechanistically, tetrabenazine binds and inhibits vesicular monoamine transporter type 2, which is responsible for importing neurotransmitters from the cytosol to the vesicles in neuronal cells. This transportation contributes to the release of neurotransmitters inside the cell to the synaptic cleft, resulting in dopaminergic signal transmission. The highly potent inhibitory activity of tetrabenazine has led to its advanced applications and in-depth investigation of prodrug design and metabolite drug discovery. In addition, the synthesis of enantiomerically pure tetrabenazine has been pursued. After a series of research studies, tetrabenazine derivatives such as valbenazine and deutetrabenazine have been approved by the US FDA. In addition, radioisotopically labeled tetrabenazine permits the early diagnosis of Parkinson’s disease, which is difficult to treat during the later stages of this disease. These applications were made possible by the synthetic efforts aimed toward the efficient and asymmetric synthesis of tetrabenazine. In this review, various syntheses of tetrabenazine and its derivatives have been summarized.

Treatment of tics associated with Tourette syndrome

Motor and phonic tics associated with Tourette syndrome (TS) can range in severity from barely perceptible to disabling and most patients have a variety of behavioral co-morbidities, particularly, attention deficit disorder and obsessive compulsive disorder. Therefore, therapy must be tailored to the individual needs of the patients. In addition to behavioral therapy, oral medications such as alpha agonists, dopamine depletors, anti-psychotics, and topiramate are used to control the involuntary movements and noises. Botulinum toxin injections are particularly effective in patients with troublesome focal motor and phonic tics, including coprolalia. Deep brain stimulation may be considered for patients with "malignant" TS, that is, refractory to medical therapy. When appropriate therapy is selected and implemented, most patients with TS can achieve their full potential and lead essentially normal life.

[Antipsychotic-induced motor symptoms in schizophrenic psychoses-Part 3 : Tardive dyskinesia]

The treatment of schizophrenic psychoses with antipsychotic drugs (AP) is often associated with an increased risk of delayed occurrence of antipsychotic-associated movement disorders. Persistence and chronicity of such symptoms are very frequent. The risk of developing tardive dyskinesia (TD) is associated with the pharmacological effect profile of a particular AP, with treatment duration and age. This systematic review article summarizes the current study situation on prevalence, risk factors, prevention and treatment options and instruments for early prediction of TD in schizophrenic psychoses. The current data situation on treatment strategies for TD is very heterogeneous. For the treatment of TD there is preliminary evidence for reduction or discontinuation of the AP, switching to clozapine, administration of benzodiazepines (clonazepam) and treatment with vesicular monoamine transporter (VMAT2) inhibitors, ginkgo biloba, amantadine or vitamin E. Although TD can be precisely diagnosed it cannot always be effectively treated. Early detection and early treatment of TD can have a favorable influence on the prognosis and the clinical outcome.

Recent developments in drug-induced movement disorders: a mixed picture

A large and ever-growing number of medications can induce various movement disorders. Drug-induced movement disorders are disabling but are often under-recognised and inappropriately managed. In particular, second generation antipsychotics, like first generation agents, are associated with potentially debilitating side-effects, most notably tardive syndromes and parkinsonism, as well as potentially fatal acute syndromes. Appropriate, evidence-based management is essential as these drugs are being prescribed to a growing population vulnerable to these side-effects, including children and elderly people. Prevention of the development of drug-induced movement disorders is an important consideration when prescribing medications that can induce movement disorders. Recent developments in diagnosis, such as the use of dopamine transporter imaging for drug-induced parkinsonism, and treatment, with the approval of valbenazine and deutetrabenazine, the first drugs indicated for tardive syndromes, have improved outcomes for many patients with drug-induced movement disorders. Future research should focus on development of safer antipsychotics and specific therapies for the different tardive syndromes and the treatment of drug-induced parkinsonism.

Real-World Experience With VMAT2 Inhibitors

OBJECTIVES

The aim of this study was to review our "real-world" experience with the vesicular monoamine transporter 2 (VMAT2) inhibitors tetrabenazine (TBZ), deutetrabenazine (DTBZ), and valbenazine (VBZ) for treatment of hyperkinetic movement disorders. Access and adherence to VMAT2 inhibitors may be limited by insurance and regulatory issues, inexperience with their use by the prescribing physician, lack of efficacy, or side effects.

METHODS

We performed a retrospective chart review, supplemented with a questionnaire, of all our patients treated with a VMAT2 inhibitor between January 1, 2017, and August 30, 2018.

RESULTS

We identified 135 patients (57.8% male) and 178 prescriptions for VMAT2 inhibitors (TBZ, n = 45 [25.3%]; DTBZ, n = 104 [58.4%]; VBZ, n = 29 [16.3%]). Tourette syndrome/tics was the most common diagnosis (n = 67 [49.6%]) for which VMAT2 inhibitors were prescribed. The VMAT2 inhibitor mean treatment durations (range; SD) and daily dosages (range; SD) were as follows: TBZ (n = 31), 5.1 months (1-19; 3.9) at 48.8 mg (12.5-112.5; 29.6); DTBZ (n = 51), 8.0 months (0.25-16.5; 4.4) at 34.4 mg (6-96; 20.7); and VBZ (n = 20), 6.0 months (0.1-16; 5.6) at 64 mg (40-160; 35.3). The VMAT2 inhibitors effectively controlled hyperkinetic movement disorders as measured by a 1- to 4-point Likert scale (1 = normal or mildly ill, 4 = severely ill) comparing illness severity before starting and while on treatment (score of 1 in 13.0%-26.7% vs 60.9%-71.9% of patients). Side effects were mild and improved or resolved following dose reduction, drug cessation, or addition of adjunctive medications.

CONCLUSIONS

The VMAT2 inhibitors are effective and safe in a range of hyperkinetic movement disorders but are not readily accessible by patients in the United States for indications not approved by the Food and Drug Administration.

Tardive Dyskinesia: New Treatments Available

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.].

Valbenazine in the treatment of tardive dyskinesia

Tardive dyskinesia (TD) is a bothersome and – at times, disabling – movement disorder associated with exposure to dopamine receptor antagonist medications. On 11 April 2017, valbenazine became the first US FDA-approved medication indicated for the treatment of TD. Valbenazine is a vesicular monoamine transporter 2 (VMAT2) inhibitor that decreases the abnormal movements of TD. The FDA considered valbenazine a breakthrough therapy in 2014 given its underlying mechanism and its importance in addressing an unmet need, as there were no available FDA-approved medications indicated for TD. The advantages of valbenazine include once-daily dosing and a rapid onset of effect within 2 weeks of treatment initiation.

Drug-induced movement disorders

Many therapeutic and illicit drugs can cause movement disorders Antipsychotics and antiemetics are most commonly implicated

The time of onset of the movement disorder may be acute subacute or chronic The severity can range from mild to severe and life-threatening

Early recognition of a drug-induced movement disorder is essential to allow for prompt intervention This includes stopping the offending drug supportive care and sometimes other pharmacological treatment

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.

Comparing pharmacologic mechanism of action for the vesicular monoamine transporter 2 (VMAT2) inhibitors valbenazine and deutetrabenazine in treating tardive dyskinesia: does one have advantages over the other?

The two approved treatments for tardive dyskinesia both inhibit the vesicular monoamine transporter type 2 (VMAT2) yet have pharmacologic properties that distinguish one from the other. Knowing these differences may help optimize which treatment to select for individual patients.