Brexpiprazole has a low risk of dopamine D2 receptor sensitization and inhibits rebound phenomena related to D2 and serotonin 5-HT2A receptors in rats

Brexpiprazole: A new option in treating agitation in Alzheimer's dementia-Insights from transgenic mouse models

AIM

Brexpiprazole is the first FDA-approved treatment for agitation associated with dementia due to Alzheimer's disease. Agitation in Alzheimer's dementia (AAD) occurs in high prevalence and is a great burden for patients and caregivers. Efficacy, safety, and tolerability of brexpiprazole were demonstrated in the AAD clinical trials. To demonstrate the agitation-ameliorating effect of brexpiprazole in animals, we evaluated brexpiprazole in two AAD mouse models.

METHODS

The resident-intruder test was conducted in 5- to 6-month-old Tg2576 mice, given vehicle or brexpiprazole (0.01 or 0.03 mg/kg) orally 1 h before the test. Locomotor activity was measured in 6-month-old APPSL-Tg mice given vehicle or brexpiprazole (0.01 or 0.03 mg/kg) orally the evening before the start of locomotor measurement for 3 days.

RESULTS

In the resident-intruder test, Tg2576 mice showed significantly higher attack number and shorter latency to first attack compared to non-Tg mice. In the Tg mice, brexpiprazole treatment (0.03 mg/kg) significantly delayed the latency to first attack and showed a trend toward a decrease in attack number. APPSL-Tg mice (≧6 months old) showed significantly higher locomotion during dark period Phase II (Zeitgeber time [ZT] 16-20) and Phase III (ZT20-24) compared to non-Tg mice, correlating with the clinical observations of late afternoon agitation in Alzheimer's disease. Brexpiprazole treatment (0.01 and 0.03 mg/kg) significantly decreased hyperlocomotion during the Phase III in APPSL-Tg mice.

CONCLUSION

The suppression of attack behavior and the reduction of nocturnal hyperlocomotion in these Tg mice may be indicative of the therapeutic effect of brexpiprazole on AAD, as demonstrated in the clinical trials.

Brexpiprazole Attenuates Aggression, Suicidality and Substance Use in Borderline Personality Disorder: A Case Series

Background: Borderline personality disorder (BPD) is a heterogeneous and highly comorbid disorder. Suicidality, aggression and substance abuse are common presentations of BPD. Our case series is the first to highlight the role of brexpiprazole in improving these symptoms in patients with BPD. Case presentation: We describe three cases demonstrating the role of brexpiprazole in improving BPD's prominent features and comorbidities. All cases improved when brexpiprazole was added to their treatment regime. Case 1: A 26-year-old woman who was diagnosed with BPD and cyclothymia, presented to the psychiatric emergency unit with impulsive suicidal behaviour. Case 2: A 43-year-old woman suffering from BPD sought help due to her violent behaviour and emotional dysregulation. Case 3: A 22-year-old woman with underlying attention deficit and hyperactivity disorder, polysubstance use disorder and BPD presented with dysregulated emotions. Conclusions: Our case series provides anecdotal evidence of the potential role of brexpiprazole in attenuating suicidality, aggression and substance abuse in patients with BPD. We postulate that brexpiprazole's high affinity for the 5HT1A/5HT2A receptors, coupled with its low intrinsic effect on the D2/D3 receptor system, is fundamental in its actions to stabilise the aberrant dopaminergic and serotonergic signalling in BPD. Future research should focus on well-designed clinical trials investigating the efficacy of brexpiprazole in patients with BPD.

Can brexpiprazole be switched safely in patients with schizophrenia and dopamine supersensitivity psychosis? A retrospective analysis in a real-world clinical practice

BACKGROUND

Several studies have reported that a switch to the dopamine partial agonist (DPA) aripiprazole (ARP), especially when the switch is abrupt, is likely to fail and sometimes worsen psychosis in schizophrenia patients already under high-dose antipsychotic treatment. Such a switching failure is speculated to be related to be the dopamine supersensitivity state. The risks of switching to the DPA brexpiprazole (BREX) have not been reported.

AIMS AND METHODS

We retrospectively analyzed the cases of 106 patients with schizophrenia to identify any factors related to the success or failure of switching to BREX.

RESULTS

The comparison between the patients with dopamine supersensitivity psychosis (n = 44) and those without (n = 62) revealed no significant difference in the switching failure judged at the sixth week. A comparison of the patients with successful switching (n = 80) and those who failed (n = 26) revealed that patients with treatment-resistant schizophrenia (TRS) were significantly more likely to fail. A logistic regression analysis also revealed that patients with past failure of switching to ARP are likely to succeed in switching to BREX. The 2-year follow-up of the patients with successful switching to BREX suggested that the patients who were treated with BREX, even temporarily, experienced some improvement in their Global Assessment of Functioning and Clinical Global Impression-Severity scores.

CONCLUSIONS

Overall, the results indicate that patients with schizophrenia can be switched more safely to BREX compared to ARP. However, the failure of switching to BREX could be higher in patients with TRS, and thus, starting BREX treatment in refractory patients warrants careful monitoring.

Dopamine partial agonists: a discrete class of antipsychotics

Worldwide, there are now three marketed dopamine D2 partial agonists: aripiprazole, brexpiprazole and cariprazine. These three drugs share a number of properties other than their action at D2 receptors. Pharmacologically, they are 5HT2 antagonists and D3 and 5HT1A partial agonists but with little or no alpha-adrenergic, anticholinergic or antihistaminic activity. They also share a long duration of action. Clinically, D2 partial agonists are effective antipsychotics and generally have useful antimanic and antidepressant activity. They are usually well tolerated, causing akathisia and insomnia only at the start of treatment, and are non-sedating. These drugs also share a very low risk of increased prolactin and of weight gain and accompanying metabolic effects. They may also have a relatively low risk of tardive dyskinesia. There is some evidence that they are preferred by patients to dopamine antagonists. Individual dopamineD2 partial agonists have much in common and as a group they differ importantly from dopamine D2 antagonists. Dopamine D2 partial agonists should be considered a distinct class of antipsychotics.Key pointsD2 partial agonists share many pharmacological and clinical propertiesD2 partial agonists differ in several important respects from D2 antagonistsD2 partial agonists should be considered a discrete class of antipsychotics.

Preclinical evidence for the use of the atypical antipsychotic, brexpiprazole, for opioid use disorder

Opioid addiction is characterized by adaptations in the mesolimbic dopamine system that occur during chronic opioid use. Alterations in dopaminergic transmission contribute to pathological drug-seeking behavior and other symptoms associated with opioid withdrawal following drug discontinuation, making drug abstinence challenging and contributing to high rates of relapse among those suffering from substance use disorder. Recently, the use of dopamine partial agonists has been proposed as a potential strategy to restore dopaminergic signalling during drug withdrawal, while avoiding the adverse side effects associated with stronger modulators of dopaminergic transmission. We investigated the effects of the atypical antipsychotic brexpiprazole, which is a partial agonist at dopamine D2 and D3 receptors, in a mouse model of opioid dependence. The development of opioid dependence in mice is characterized by locomotor sensitization, analgesic tolerance, opioid-induced hyperalgesia, and drug-seeking behavior. We set up four paradigms to model the effects of brexpiprazole on each of these adaptations that occur during chronic opioid use in male and female C57BL/6J mice. Concomitant treatment of brexpiprazole during chronic morphine administration attenuated the development of locomotor sensitization. Brexpiprazole treatment abolished morphine place preference and blocked reinstatement of this behavior following extinction. Brexpiprazole treatment did not alter morphine analgesia, nor did it impact the development of morphine tolerance. However, brexpiprazole treatment did prevent the expression of opioid-induced hyperalgesia in a tail-withdrawal assay, while failing to improve somatic withdrawal symptoms. Altogether, these results provide preclinical evidence for the efficacy of brexpiprazole as a modulator of dopamine-dependent behaviors during opioid use and withdrawal.

Synergistic anti-depressive effect of combination treatment of Brexpiprazole and selective serotonin reuptake inhibitors on forced swimming test in mice

AIM

Selective serotonin reuptake inhibitors (SSRIs) are used to treat major depressive disorder (MDD) and other psychiatric disorders (e.g., obsessive compulsive disorder, social anxiety disorder, and panic disorder). In MDD treatment, SSRIs do not show remission in approximately 30% of patients, indicating a need for a better treatment option. Forced swimming test (FST) is a behavioral assay to evaluate depression-like behavior and antidepressant efficacy in rodents. In the present study, we evaluated the combination effect of brexpiprazole with SSRIs on FST in mice, in order to investigate their synergistic effect.

METHODS

Brexpiprazole (0.003 mg/kg) was intraperitoneally injected to mice 15 min before testing. Escitalopram (10 mg/kg), fluoxetine (75 mg/kg), paroxetine (10 mg/kg), or sertraline (15 mg/kg) were orally administered to mice 60 min before testing. Then, the mice were placed in water and immobility time was measured. Data from animals treated with escitalopram, fluoxetine, paroxetine, and sertraline were pooled as SSRI-treated group data.

RESULTS

Combination treatment of brexpiprazole with SSRIs reduced immobility time in FST more than vehicle or each single treatment. A significant interaction effect was confirmed in the combination of brexpiprazole and SSRIs (p = 0.0411).

CONCLUSION

Efficacy of adjunctive brexpiprazole has already been demonstrated in clinical trials in MDD patients not adequately responding to antidepressants including escitalopram, fluoxetine, paroxetine, and sertraline. The synergistic antidepressant-like effect of brexpiprazole with SSRIs found in this study supports the already known clinical findings.

Spontaneous head twitches in aged rats: behavioral and molecular study

RATIONALE

We have discovered that rats at the age of 18 months begin to twitch their heads spontaneously (spontaneous head twitching, SHT). To date, no one has described this phenomenon.

OBJECTIVES

The purpose of this study was to characterize SHT pharmacologically and to assess some possible mechanisms underlying SHT.

METHODS

Wistar male rats were used in the study. Animals at the age of 18 months were qualified as HSHT (SHT ≥ 7/10 min observations) or LSHT (SHT < 7/10 min observations). Quantitative real-time PCR with TaqMan low-density array (TLDA) approach was adopted to assess the mRNA expression of selected genes in rat's hippocampus.

RESULTS

HSHT rats did not differ from LSHT rats in terms of survival time, general health and behavior, water intake, and spontaneous locomotor activity. 2,5-dimethoxy-4-iodoamphetamine (DOI) at a dose of 2.5 mg/kg increased the SHT in HSHT and LSHT rats, while ketanserin dose-dependently abolished the SHT in the HSHT rats. The SHT was reduced or abolished by olanzapine, clozapine, risperidone, and pimavanserin. All these drugs have strong 5-HT2A receptor-inhibiting properties. Haloperidol and amisulpride, as antipsychotic drugs with a mostly dopaminergic mechanism of action, did not influence SHT. Similarly, escitalopram did not affect SHT. An in-depth gene expression analysis did not reveal significant differences between the HSHT and the LSHT rats.

CONCLUSIONS

SHT appears in some aging rats (about 50%) and is permanent over time and specific to individuals. The 5-HT2A receptor strongly controls SHT. HSHT animals can be a useful animal model for studying 5-HT2A receptor ligands.

The Role of G Protein-Coupled Receptors (GPCRs) and Calcium Signaling in Schizophrenia. Focus on GPCRs Activated by Neurotransmitters and Chemokines

Schizophrenia is a common debilitating disease characterized by continuous or relapsing episodes of psychosis. Although the molecular mechanisms underlying this psychiatric illness remain incompletely understood, a growing body of clinical, pharmacological, and genetic evidence suggests that G protein-coupled receptors (GPCRs) play a critical role in disease development, progression, and treatment. This pivotal role is further highlighted by the fact that GPCRs are the most common targets for antipsychotic drugs. The GPCRs activation evokes slow synaptic transmission through several downstream pathways, many of them engaging intracellular Ca²⁺ mobilization. Dysfunctions of the neurotransmitter systems involving the action of GPCRs in the frontal and limbic-related regions are likely to underly the complex picture that includes the whole spectrum of positive and negative schizophrenia symptoms. Therefore, the progress in our understanding of GPCRs function in the control of brain cognitive functions is expected to open new avenues for selective drug development. In this paper, we review and synthesize the recent data regarding the contribution of neurotransmitter-GPCRs signaling to schizophrenia symptomology.

Discovery research and development history of the dopamine D2 receptor partial agonists, aripiprazole and brexpiprazole

Otsuka Pharmaceutical Co., Ltd. successfully developed the first dopamine D₂ receptor partial agonist approved for schizophrenia, the antipsychotic aripiprazole (Abilify^®). The drug was approved for this indication in the United States in 2002 and has received approval in the United States, Europe, Japan, and many other countries for several indications including schizophrenia, acute mania, adjunctive treatment of major depressive disorder (MDD), irritability associated with autistic disorder, and Tourette's disorder. Otsuka next developed brexpiprazole (Rexulti^®), another D₂ receptor partial agonist, which was granted marketing approval in the United States in 2015 as adjunctive therapy in major depressive disorder and for the treatment of schizophrenia. In Japan, brexpiprazole also received approval as a treatment for schizophrenia in 2018. In this review, we describe Otsuka's research history and achievements over the preceding 40 years in the area of antipsychotic drug discovery for dopamine D₂ receptor partial agonists.

“Dopamine‐system stabilizer” activity of aripiprazole.

Treatment-resistant schizophrenia characterised by dopamine supersensitivity psychosis and efficacy of asenapine

Dopamine supersensitivity psychosis (DSP) frequently arises with long-term antipsychotic treatment and accounts for a significant proportion of treatment-resistant schizophrenia. The mechanism underlying DSP is thought to be a compensatory increase in dopamine receptor density in the striatum caused by long-term antipsychotic treatment. Previous animal studies have reported that antipsychotics increase serotonin 5-HT2A receptor density in the striatum and that 5-HT2A receptor blockers suppress dopamine-sensitive psychomotor activity, which may be linked to the pathophysiology of DSP. In this paper, we describe a patient who was hospitalised with treatment-resistant schizophrenia. Following treatment with high-dose antipsychotic polypharmacy for 10 weeks, the patient experienced worsening of psychotic and extrapyramidal symptoms. The patient was then started on second-generation antipsychotic asenapine while other antipsychotics were tapered off, resulting in improvement of these symptoms. Retrospectively, we presumed that the high-dose antipsychotic polypharmacy caused DSP, which was effectively treated by the potent 5-HT2A receptor antagonism of asenapine.

Rationale and neurobiological effects of treatment with antipsychotics in patients with chronic schizophrenia considering dopamine supersensitivity

The long-term treatment of patients with schizophrenia often involves the management of relapses for most patients and the development of treatment resistance in some patients. To stabilize the clinical course and allow as many patients as possible to recover, clinicians need to recognize dopamine supersensitivity, which can be provoked by administration of high dosages of antipsychotics, and deal with it properly. However, no treatment guidelines have addressed this issue. The present review summarized the characteristics of long-acting injectable antipsychotics, dopamine partial agonists, and clozapine in relation to dopamine supersensitivity from the viewpoints of receptor profiles and pharmacokinetics. The potential merits and limitations of these medicines are discussed, as well as the risks of treating patients with established dopamine supersensitivity with these classes of drugs. Finally, the review discussed the biological influence of antipsychotic treatment on the human brain based on findings regarding the relationship between the hippocampus and antipsychotics.

Effect of Switching to Brexpiprazole on Plasma Homovanillic Acid Levels and Antipsychotic-Related Side Effects in Patients with Schizophrenia or Schizoaffective Disorder

OBJECTIVE

Although switching antipsychotics is a common strategy in the treatment of schizophrenia, caution is needed because of the risk of worsening of psychosis, particularly when switching to a dopamine D2 partial agonist. Homovanillic acid (HVA), a dopamine metabolite, is thought to be a possible indicator of the response to antipsychotics. We examined the effects of switching to brexpiprazole monotherapy from other antipsychotics on plasma HVA levels and side effects during maintenance treatment of schizophrenia.

METHODS

The antipsychotics of 37 Japanese patients with schizophrenia or schizoaffective disorder were switched to brexpiprazole for the improvement of side effects. We evaluated clinical symptoms and extrapyramidal symptoms (EPS) and took fasting blood samples at baseline and endpoint (eight weeks after completing the switch) to measure plasma levels of HVA, prolactin, and metabolic parameters.

RESULTS

Switching to brexpiprazole significantly decreased the Drug-Induced Extrapyramidal Symptoms Scale total score (p=0.008), prolactin levels (p<0.001), body weight (p=0.046), and body-mass index (p=0.034), and increased HDL cholesterol (p=0.008). On the other hand, switching to brexpiprazole did not change plasma levels of HVA or Positive and Negative Syndrome Scale scores.

CONCLUSION

Switching to brexpiprazole significantly improved EPS, high prolactin levels, and metabolic side effects without elevating plasma HVA levels. Brexpiprazole may stabilize dopaminergic neural transmission and could be a useful strategy to decrease the burden in patients with schizophrenia during the maintenance phase. Because of the small sample size, further studies with larger sample sizes are needed to confirm and extend our results.

Brexpiprazole for the Treatment of Schizophrenia in Adults: An Overview of Its Clinical Efficacy and Safety and a Psychiatrist's Perspective

While the prognosis of patients with schizophrenia has dramatically improved after the advent of chlorpromazine, the antipsychotics currently available are so numerous that it has become a challenge for psychiatrists to choose from among these drugs for each patient presenting for care. In addition, while numerous studies show that an effective antipsychotic should be continued indefinitely to prevent relapses or worsening, many patients appear to have difficulty remaining on any drug thus initiated. Brexpiprazole, a dopamine D₂ receptor partial agonist, appears to provide a unique profile that has much to offer in this light. Specifically, this novel drug is potentially better suited for long-term use, with decreased risk of extrapyramidal side effects, hyperprolactinemia, weight gain, psychosis, insomnia, akathisia, nausea/vomiting or restlessness, thus potentially facilitating patients' reintegration into society. Indeed, brexpiprazole has been shown in randomized, double-blind, placebo-controlled trials to have proven efficacy not only in improving the symptoms of schizophrenia but in preventing relapses. It is also suggested in both short- and long-term studies that brexpiprazole offers a favorable safety and tolerability profile. This review also includes a proposed treatment algorithm incorporating brexpiprazole, based on the clinical trial results available, as well as on the authors' clinical experience, where brexpiprazole may be best used as a drug of first choice for the treatment of schizophrenia. Thus, overall, brexpiprazole appears to play a more significant role in the treatment of schizophrenia than other antipsychotics.

Dopamine D2 up-regulation in psychosis patients after antipsychotic drug treatment

PURPOSE OF REVIEW

Recently, it has been questioned whether the re-emergence of psychotic symptoms following antipsychotic discontinuation or dose reduction is attributable to underlying psychotic vulnerability or to rebound effects of chronic use of antipsychotic medication. It was repeatedly shown that relapse rates are high after discontinuation of maintenance treatment. A potential contributing factor could be the increase in density of postsynaptic dopamine D2 receptors in the striatum and the higher affinity of D2 receptors for dopamine after chronic blockade.

RECENT FINDINGS

To date, little clinical evidence is available for the mechanisms involved in postsynaptic striatal D2 receptor up-regulation after use of antipsychotic medication, and most knowledge comes from animal studies.

SUMMARY

Further research is needed to investigate whether antipsychotic medication causes neuroadaptations leading to a dopamine supersensitive state in humans, how long such hypersensitive states may last and what differences exist between high and low D2 affinity antipsychotic drugs. Further, information is needed on discontinuation schedules that provide optimal protection for relapse during hypersensitive periods.

Efficacy and safety of brexpiprazole in acute management of psychiatric disorders: a meta-analysis of randomized controlled trials

Brexpiprazole is a new atypical antipsychotic for schizophrenia management and as adjunct in major depressive disorder (MDD). We searched randomized controlled trials (RCT) to review brexpiprazole efficacy and tolerability in acute management of schizophrenia and MDD using PubMed, EUDRACT, ClinicalTrials.gov and Cochrane Central Register of Controlled Trials. A meta-analysis was conducted using the identified 14 RCT to assess its efficacy using positive and negative syndrome scale (PANSS), clinical global impressions - severity of illness (CGI-S), personal and social performance scale (PSP), Montgomery-Åsberg depression rating scale (MADRS), Sheehan disability scale (SDS) and Hamilton depression rating scale (HDRS17). The mean difference comparing brexpiprazole and placebo were PANSS -4.48, CGI-S -0.23 and PSP 3.24 favoring brexpiprazole. Compared to aripiprazole and quetiapine, brexpiprazole showed similar efficacy. In MDD, brexpiprazole showed efficacy compared to placebo demonstrated by MADRS -1.25, SDS -0.37 and HDRS17 -1.28. Brexpiprazole was associated with side effects including akathisia risk ratio (RR) = 1.72; weight increase RR = 2.74 and somnolence RR = 1.87. Compared to 4 mg, brexpiprazole 2 mg was associated with less risk of akathisia and somnolence. Brexpiprazole demonstrated significant improvements in schizophrenia and MDD and is well-tolerated; however, associated with akathisia and somnolence. These findings will guide psychiatrists and pharmacists in their clinical role for supporting psychiatric patients care.

[Preclinical pharmacological profiles and clinical efficacy of the novel antipsychotic drug brexpiprazole (REXULTI® Tablets 1 mg, 2 mg)]

Brexpiprazole (Rexulti^®) is the second antipsychotic agent in the world with dopamine D2 receptor partial agonist which was developed by Otsuka Pharmaceutical Co. Ltd. It is categorized as 〝Serotonin- dopamine Activity Modulator (SDAM)〟 that regulates both serotoninergic and dopaminergic systems by acting as a partial agonist for serotonin 5-HT1A receptors and D2 receptors and as an antagonist for 5-HT2A receptors. In preclinical pharmacological studies, brexpiprazole showed the equivalent antipsychotic-like effects to those of other atypical antipsychotics. And it was suggested that brexpiprazole has the low potentials to induce extrapyramidal symptoms, hyperprolactinemia and tardive dyskinesia, with improvement effects on cognitive dysfunction. Furthermore, brexpiprazole has the weak effects on histamine H1 receptors which are associated with sedation and weight gain in clinical. In the clinical trials in patients with schizophrenia in both acute and maintenance phase, brexpiprazole showed improvement of antipsychotic effects against placebo, and low incidence of adverse events, e.g., extrapyramidal symptoms, hyperprolactinemia, and weight gain, as suggested in preclinical studies. Furthermore, brexpiprazole showed low incidence of metabolic abnormalities. In particular, brexpiprazole showed relatively low incidences of akathisia, insomnia and agitation which has been commonly reported with aripiprazole. This would be based on the pharmacological features of brexpiprazole that is more potent antagonism at 5-HT2A receptors and D2 receptors partial agonism with lower intrinsic activity compared to those of aripiprazole. In conclusion, brexpiprazole could be one of the antipsychotics with the most rational mechanism of action, and the better efficacy and safety/tolerability profiles would contribute to the treatment of patients with schizophrenia.

Brexpiprazole has a low risk of dopamine D2 receptor sensitization and inhibits rebound phenomena related to D2 and serotonin 5-HT2A receptors in rats

Background

Long‐term antipsychotic treatment in patients with schizophrenia can induce supersensitivity psychosis and tardive dyskinesia which is thought to be caused by dopamine D₂ receptor sensitization. We evaluated the effects of brexpiprazole on D₂ receptor sensitivity after subchronic treatment in rats. We also evaluated whether brexpiprazole could suppress enhanced response to D₂ receptors in rats subchronically dosed with another atypical antipsychotic.

Methods

The maximum D₂ receptor density (B_max) and apomorphine (a D₂ receptor agonist)‐induced stereotypy were measured in rats orally dosed with vehicle, haloperidol (1 mg/kg), or brexpiprazole (4 or 30 mg/kg for B_max, 6 or 30 mg/kg for stereotypy) for 21 days. Then, effects of oral administrations of brexpiprazole (3 mg/kg), aripiprazole (10 mg/kg), and olanzapine (3 mg/kg) against increases in apomorphine‐induced hyperlocomotion and (±)‐2,5‐dimethoxy‐4‐iodoamphetamine hydrochloride (DOI: a 5‐HT_2A receptor agonist)‐induced head twitches were evaluated in rats subcutaneously treated with risperidone (1.5 mg/kg/d) via minipumps for 21 days.

Results

Haloperidol and brexpiprazole (30 mg/kg: approximately tenfold ED₅₀ of anti‐apomorphine‐induced stereotypy) but not brexpiprazole (4 or 6 mg/kg) significantly increased the B_max and apomorphine‐induced stereotypy. Brexpiprazole (3 mg/kg) and olanzapine (3 mg/kg) significantly suppressed both increases in apomorphine‐induced hyperlocomotion and also DOI‐induced head twitches in rats subchronically treated with risperidone, but aripiprazole (10 mg/kg) significantly suppressed only apomorphine‐induced hyperlocomotion.

Conclusion

Brexpiprazole has a low risk of D₂ receptor sensitization after a repeated administration and suppresses the rebound phenomena related to D₂ and 5‐HT_2A receptors after a repeated administration of risperidone.

Brexpiprazole has less potential to evoke dopamine D2 receptor supersensitivity in rats after repeated administration compared to haloperidol. In addition, brexpiprazole may have a lower risk for producing rebound symptoms associated with D2 receptor, 5‐HT2A receptor sensitization when switching from other antipsychotics such as risperidone.