Brexpiprazole II: antipsychotic-like and procognitive effects of a novel serotonin-dopamine activity modulator

Third-Generation Antipsychotics: The Quest for the Key to Neurotrophism

Antipsychotic drugs (APs) have profoundly changed the treatment landscape for psychiatric disorders, yet their impact on neuroplasticity and neurotrophism remains only partially understood. While second-generation antipsychotics (SGAs) are associated with a better side effect profile than their predecessors, the emergence of third-generation antipsychotics (TGAs)-such as brexpiprazole, cariprazine, lurasidone, iloperidone, lumateperone, pimavanserin, and roluperidone-has prompted renewed interest in their potential neuroprotective and pro-cognitive effects. This review attempts to carefully examine the evidence on the neurotrophic properties of TGAs and their role in modulating brain plasticity by analyzing studies published between 2010 and 2024. Although data remain limited and focused primarily on earlier SGAs, emerging findings suggest that some TGAs may exert positive effects on neuroplastic processes, including the modulation of brain-derived neurotrophic factors (BDNFs) and synaptic architecture. However, robust clinical data on their long-term effects and comparative efficacy are lacking; therefore, further research is necessary to validate their role in preventing neurodegenerative changes and improving cognitive outcomes in patients with psychiatric conditions.

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.

Third-Generation Antipsychotics and Lurasidone in the Treatment of Substance-Induced Psychoses: A Narrative Review

This narrative review explores the efficacy and tolerability of third-generation antipsychotics (TGAs)-aripiprazole, cariprazine, brexpiprazole, and lurasidone-for the management of substance-induced psychosis (SIP). SIP is a psychiatric condition triggered by substance misuse or withdrawal, characterized by unique features distinct from those of primary psychotic disorders. These distinctive features include a heightened prevalence of positive symptoms, such as hallucinations and delusions, in addition to a spectrum of mood and cognitive disturbances. This review comprehensively investigates various substances, such as cannabinoids, cocaine, amphetamines, and LSD, which exhibit a greater propensity for inducing psychosis. TGAs exhibit substantial promise in addressing both psychotic symptoms and issues related to substance misuse. This review elucidates the distinctive pharmacological properties of each TGA, their intricate interactions with neurotransmitters, and their potential utility in the treatment of SIP. We advocate for further research to delineate the long-term effects of TGAs in this context and underscore the necessity for adopting an integrated approach that combines pharmacological and psychological interventions. Our findings underscore the intricate and multifaceted nature of treating SIP, highlighting the potential role of TGAs within therapeutic strategies.

Brexpiprazole in patients with schizophrenia with or without substance use disorder: an observational study

Background

Partial dopamine D2 receptor agonists are used for psychotic symptoms in adults with schizophrenia spectrum disorders. Recently, interest surged for partial dopamine D2 receptor agonists in substance use disorders (SUDs). Since it is believed that SUDs decrease the efficacy of pharmacotherapy of underlying psychiatric disorders, we tested the efficacy of the partial D2 agonist brexpiprazole in patients with schizophrenia who were either comorbid with a SUD (SUD group) or not comorbid (non-SUD) to assess treatment response and the effect of brexpiprazole on substance craving in SUD.

Methods

We included patients with DSM-5/DSM-5-TR schizophrenia (using SCID-5-CV) aged 18-66 years with either comorbid SUD or non-SUD to treat with brexpiprazole 4 mg/day for 6 months during February-October 2022. Patients were assessed with the Clinical Global Impressions-Severity (CGI-S) scale, the 24-item Brief Psychiatric Rating Scale (BPRS), and the Positive And Negative Syndrome Scale (PANSS) at baseline, weekly for the first 2 months and monthly for the next four. Furthermore, we assessed substance craving in SUD with a visual analog scale for craving (VAScrav) at the same timepoints.

Results

The total sample was 86 (85 analysable) 18- to 64-year-old (mean 39.32 ± 14.09) patients with schizophrenia [51 men (59.3%) and 35 women (40.7%)], of whom 48 SUD (55.8%) (37 men and 11 women) and 38 non-SUD (44.2%) (14 men and 24 women). No serious or persistent adverse events developed over the study period, but one patient dropped out for subjective akathisia. Results indicated the main effects of time with improvements over the course of the study for CGI-S, BPRS, and PANSS in both SUD and non-SUD groups and the entire sample, and for VAScrav in SUD. Brexpiprazole was associated with similar significant improvements in both groups at the 6 month endpoint compared to baseline.

Conclusion

Treatment with brexpiprazole for 6 months improved psychotic symptoms in patients with schizophrenia, independently from whether they belonged to the SUD or the non-SUD group; hence, SUD comorbidity did not confer treatment resistance to brexpiprazole. Furthermore, in the SUD group, we observed reduced substance craving.

Creation of a ready-to-use brexpiprazole suspension and the inflammation-mediated pharmacokinetics by intramuscular administration

Brexpiprazole (BPZ), which is approved for the treatment of schizophrenia and major depressive disorder, has the potential to meet diverse clinical needs. This study aimed to develop a long-acting injectable (LAI) formulation of BPZ that could provide sustained therapeutic benefits. A library of BPZ prodrugs was screened through esterification, and BPZ laurate (BPZL) was identified as an optimal candidate. To achieve stable aqueous suspensions, a pressure- and nozzle size-controlled microfluidization homogenizer was utilized. The pharmacokinetics (PK) profiles, considering dose and particle size modulation, were investigated following a single intramuscular injection in beagles and rats. BPZL treatment resulted in sustained plasma concentrations above the median effective concentration (EC₅₀) for 2∼3 weeks, without exhibiting an initial burst release. Histological examination of foreign body reaction (FBR) in rats revealed the morphological evolution of an inflammation-mediated drug depot, confirming the sustained release mechanism of BPZL. These findings provide strong support for the further development of a ready-to-use LAI suspension of BPZL, which could potentially enhance treatment outcomes, improve patient adherence, and address the clinical challenges associated with long-term regimens of schizophrenia spectrum disorders (SSD).

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.

Analysis of the effect of brexpiprazole on sleep architecture in patients with schizophrenia: A preliminary study

BACKGROUND

Brexpiprazole is an atypical antipsychotic drug widely used in Japan for the treatment of schizophrenia. Previous studies have investigated the therapeutic effects of some antipsychotics on sleep variables; however, to our knowledge, the effects of brexpiprazole on sleep architecture have not been examined in patients with schizophrenia. Therefore, we aimed to exploratorily investigate the effect of brexpiprazole on sleep variables measured by polysomnography in patients with schizophrenia.

METHODS

This study included 10 patients with schizophrenia who were originally treated with haloperidol alone. Sleep variables of the participants were measured using polysomnography. After excluding those who did not meet the study criteria, seven patients (five men and two women; mean age [SD], 59.0 [10.0] years) were eligible for further analysis. Polysomnography was repeated at 4 weeks after the participants were prescribed brexpiprazole in addition to haloperidol. We compared the sleep architecture of the participants, measured using polysomnography, before and after taking brexpiprazole.

RESULTS

Add-on brexpiprazole significantly prolonged rapid eye movement latency, increased the duration and percentage of stage N2 and stage N3 sleep (min, %), and decreased the duration and percentage of stage rapid eye movement sleep (min, %) at a significance level of nominal p < 0.05.

CONCLUSION

Although not significant after correcting for multiple comparisons, the present results showed that add-on brexpiprazole could alter the sleep architecture of patients with schizophrenia. Future studies are warranted to replicate these findings and to further investigate the beneficial influence of brexpiprazole on sleep.

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.

Seventy Years of Antipsychotic Development: A Critical Review

Since the mid-1950s discovery of the first effective antipsychotic medications (APM), we have only been able to improve the tolerability but not the overall efficacy of currently available APMs, as reflected by effectiveness trials in Europe and the United States. This inability to develop more effective APMs is attributable to multiple factors, including failure to create and use assessment tools to assess core symptom domains in schizophrenia, move beyond the dopaminergic hypothesis and to develop "me too" drugs, imposing ill-defined research domain criteria, and lacking federal funding for clinical trials. The classification of APMs is also confusing, including second-generation, partial agonists, and multimodal APMs in the same class of APMs, despite significant differences in their mechanisms of action. Other factors stagnating drug development include inadequate sample sizes to address heterogeneity, lack of statistical measures correlating with clinical significance, using the atheoretical basis of psychiatric diagnoses, failure to control placebo response, and high cost of newer and perhaps more tolerable APMs. Furthermore, there has been a failure to develop early predictors of antipsychotic response and various tools to optimize an APM response. Finally, some mental health providers are also responsible for the suboptimal use of APMs, by using excessive maintenance doses, often with irrational polypharmacy, further compromising effectiveness and medication adherence. However, some bright spots in antipsychotic development include improved tolerability of APMs and long-acting injectables to address the high prevalence of medication nonadherence. This review critically reviews 70 years of antipsychotic development, the reasons behind the failure to develop more effective APMs, and suggestions for future direction.

Treatment Discontinuation Among Patients with Schizophrenia Treated with Brexpiprazole and Other Oral Atypical Antipsychotics in Japan: A Retrospective Observational Study

Introduction

Treatment continuation is essential for relapse prevention in patients with schizophrenia. The aim of this exploratory study was to compare the time to treatment discontinuation between patients with schizophrenia prescribed brexpiprazole (BRX group) and those prescribed other atypical antipsychotics (OAA group) in clinical settings in Japan using health insurance claims data.

Methods

De-identified data of working individuals with schizophrenia aged < 75 years and their dependents were assessed from April 2017 to May 2020 using a nationwide claims database. Cox proportional hazards models, adjusted for baseline patient variables, were used to compare the time to treatment discontinuation (primary outcome) for 180 days between BRX and OAA groups and to estimate the hazard ratio (HR) with 95% confidence interval (CI). The cumulative treatment continuation rates at 180 days were also estimated. Sensitivity and subgroup analyses were conducted for the primary outcome.

Results

The analysis included 978 and 4898 patients in the BRX and OAA groups, respectively. Patients in the BRX group were significantly less likely to discontinue treatment than those in the OAA group (HR 0.86, 95% CI 0.78–0.95; p = 0.0024). The cumulative treatment continuation rates were higher in the BRX group (45.9%, 95% CI 42.5–49.2]) than in the OAA group (39.5%, 95% CI 38.1–41.0; log-rank test, p < 0.0001). Based on patients matched by propensity score, the BRX group was significantly less likely to discontinue treatment than the OAA group (log-rank test, p = 0.0466). Similar results were obtained in sensitivity and subgroup analyses.

Conclusion

This real-world study showed that patients in the BRX group were less likely to discontinue treatments than those in the OAA group. These findings suggest that BRX may contribute to treatment continuation among patients with schizophrenia.

Trial Registration

University hospital Medical Information Network (UMIN) Clinical Trials Registry: UMIN000044682.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-022-02252-9.

Abnormal synaptic plasticity and impaired cognition in schizophrenia

Schizophrenia (SCZ) is a severe mental illness that affects several brain domains with relation to cognition and behaviour. SCZ symptoms are typically classified into three categories, namely, positive, negative, and cognitive. The etiology of SCZ is thought to be multifactorial and poorly understood. Accumulating evidence has indicated abnormal synaptic plasticity and cognitive impairments in SCZ. Synaptic plasticity is thought to be induced at appropriate synapses during memory formation and has a critical role in the cognitive symptoms of SCZ. Many factors, including synaptic structure changes, aberrant expression of plasticity-related genes, and abnormal synaptic transmission, may influence synaptic plasticity and play vital roles in SCZ. In this article, we briefly summarize the morphology of the synapse, the neurobiology of synaptic plasticity, and the role of synaptic plasticity, and review potential mechanisms underlying abnormal synaptic plasticity in SCZ. These abnormalities involve dendritic spines, postsynaptic density, and long-term potentiation-like plasticity. We also focus on cognitive dysfunction, which reflects impaired connectivity in SCZ. Additionally, the potential targets for the treatment of SCZ are discussed in this article. Therefore, understanding abnormal synaptic plasticity and impaired cognition in SCZ has an essential role in drug therapy.

Polypharmacology: The science of multi-targeting molecules

Polypharmacology is a concept where a molecule can interact with two or more targets simultaneously. It offers many advantages as compared to the conventional single-targeting molecules. A multi-targeting drug is much more efficacious due to its cumulative efficacy at all of its individual targets making it much more effective in complex and multifactorial diseases like cancer, where multiple proteins and pathways are involved in the onset and development of the disease. For a molecule to be polypharmacologic in nature, it needs to possess promiscuity which is the ability to interact with multiple targets; and at the same time avoid binding to antitargets which would otherwise result in off-target adverse effects. There are certain structural features and physicochemical properties which when present would help researchers to predict if the designed molecule would possess promiscuity or not. Promiscuity can also be identified via advanced state-of-the-art computational methods. In this review, we also elaborate on the methods by which one can intentionally incorporate promiscuity in their molecules and make them polypharmacologic. The polypharmacology paradigm of "one drug-multiple targets" has numerous applications especially in drug repurposing where an already established drug is redeveloped for a new indication. Though designing a polypharmacological drug is much more difficult than designing a single-targeting drug, with the current technologies and information regarding different diseases and chemical functional groups, it is plausible for researchers to intentionally design a polypharmacological drug and unlock its advantages.

Efficacy and Safety of Low-Dose Brexpiprazole for Acute Schizophrenia: Meta-Analysis of Randomized Placebo-Controlled Trials

PURPOSE

The purpose of this meta-analysis was to compare the efficacy and safety profile of low-dose brexpiprazole (<2 mg/d) compared to placebo and standard-dose brexpiprazole (2-4 mg/d).

PATIENTS AND METHODS

We identified relevant studies pertaining to the specific purpose of our meta-analysis by searching PubMed, Web of Science, Embase, Cochrane library, and PsycINFO using the search terms "schizophrenia" or "schizophrenic" AND "brexpiprazole" or "REXULTI". We systematically reviewed all randomized controlled trials (RCTs) comparing low-dose brexpiprazole with placebo. Primary efficacy outcomes were the PANSS total score change and response rate. Primary safety outcomes were total treatment discontinuation rate, and total serious adverse events (SAEs). Risk ratios (RR) and standardized mean differences (SMDs) were pooled implementing a random effect model.

RESULTS

Four RCTs (2178 patients) were included for effect assessment of low-dose brexpiprazole treatment on the patients with acute schizophrenia. Low-dose brexpiprazole was not superior to placebo (SMD = -0.11, 95% CI = -0.23, 0.02, P = 0.10, I² = 0%), and significantly inferior to standard-dose brexpiprazole (SMD = 0.15, 95% CI = 0.03, 0.26, P = 0.01, I² = 0%) for PANSS total score change. Low-dose brexpiprazole did not result in significant difference for response rate when compared to placebo and standard-dose brexpiprazole (RR = 1.16, 95% CI = 0.95, 1.41, P = 0.14, I² = 25%; RR = 0.92, 95% CI = 0.76, 1.12, P = 0.40, I² = 38%, respectively). For ratio of total discontinuation, low-dose brexpiprazole did not exhibit significant difference when compared to placebo (RR = 0.95, 95% CI = 0.81, 1.11, P = 0.53, I² = 0%) and standard-dose brexpiprazole group (RR = 1.11, 95% CI = 0.95, 1.29, P = 0.19, I² = 0%). Total SAEs in low-dose brexpiprazole group did not differ significantly from placebo and standard-dose brexpiprazole group (RR = 0.96, 95% CI = 0.52, 1.80, P = 0.90, I² = 0%; RR = 1.29, 95% CI = 0.65, 2.57, P = 0.47, I² = 26%, respectively).

CONCLUSION

The results indicated that low-dose brexpiprazole may be not superior for improving the efficacy and safety for acute schizophrenia compared to placebo and standard-dose brexpiprazole, and may cause additional risk of increasing body weight. Therefore, using low-dose brexpiprazole in acute schizophrenia patients may be not recommended.

Newer antipsychotics: Brexpiprazole, cariprazine, and lumateperone: A pledge or another unkept promise?

Antipsychotic agents are used for various indications in the treatment of psychiatric disorders. Despite their proven roles in multiple conditions, the treatment-emergent side effects of antipsychotic medications, such as metabolic side effects, are often the limiting factor for their long-term and short-term uses. Moreover, antipsychotic medications are often criticized for being less effective in treating different disabling symptoms such as negative symptoms of schizophrenia. As a result, the search for safer and more efficacious antipsychotic agents is ongoing. Newer antipsychotic agents are gaining attention related to emerging efficacy and tolerability data in treating neuropsychiatric conditions. In this review, we attempt to appraise the scientific data on psychopharmacology, safety profile, and efficacy of the newer additions to the list of second-generation antipsychotics, namely brexpiprazole, cariprazine, and lumateperone. We conducted a selective review utilizing PubMed, clinicaltrials.gov, and Cochrane databases to gather appropriate publications, keeping broad inclusion criteria. There were no restrictions on the age of the study population or the year of publication. We also cross-referenced articles and references to capture all existing studies. Our review of the current literature indicates that all three antipsychotic agents appear to be promising based on their short-term studies, while long-term studies remain limited. There is also a need for a head to head comparison between the newer antipsychotics with the other antipsychotic agents to ascertain if the newer agents are any better than the others.

A double-blind placebo-controlled study of brexpiprazole for the treatment of borderline personality disorder

BACKGROUND

Borderline personality disorder is associated with impaired quality of life and has a number of untoward public health associations. There is no established first-line pharmacological treatment for borderline personality disorder, and available options are not suitable for all individuals.

AIMS

To evaluate brexpiprazole, which has effects on the dopaminergic and serotonergic systems, for the reduction of borderline personality disorder symptoms.

METHOD

Eighty adults with borderline personality disorder were recruited for a randomised, double-blind placebo-controlled study. Participants received 12-week treatment with brexpiprazole (1 mg/day for 1 week, then increasing to 2 mg/day) or placebo in a parallel design. The primary efficacy outcome measure was the clinician-rated Zanarini Rating Scale for Borderline Personality Disorder (ZAN-BPD). Safety data were collected. Effects of active versus placebo treatment were characterised with linear repeated measures models.

RESULTS

There was a significant interaction between treatment and time on the ZAN-BPD scale (P = 0.0031), solely because of differentiation specifically at week 12. Brexpiprazole was generally well tolerated. Secondary measures did not result in statistically significant differences from placebo.

CONCLUSIONS

Brexpiprazole appears to have some possible effect on borderline personality disorder symptoms, but further studies are needed because of the significant effects evident, specifically at the final time point. These findings also need to be viewed cautiously, given the small sample size, large drop-out rate and robust placebo response.

Contrasting Typical and Atypical Antipsychotic Drugs

The beliefs that antipsychotic drugs (APDs) are 1) effective only to treat delusions and hallucinations (positive symptoms), 2) that typical and atypical APDs differ only in ability to cause extrapyramidal side effects, and 3) that their efficacy as antipsychotics is due solely to their dopamine D₂ receptor blockade are outmoded concepts that prevent clinicians from achieving optimal clinical results when prescribing an APD. Atypical APDs are often more effective than typical APDs in treating negative symptoms, cognitive impairment, and mood symptoms as well as reducing the risk for suicide and decreasing aggression. This applies not only to those diagnosed with schizophrenia or schizoaffective disorder but also to bipolar disorder, major depression, and other psychiatric diagnoses. The greater advantage of an atypical APD is not evident in all patients for every atypical APD due, in part, to individual differences in genetic and epigenetic endowment and differences in the pharmacology of the atypical APDs, their mode of action being far more complex than that of the typical APDs. A common misconception is that among the atypical APDs, only clozapine is effective for reducing psychosis in treatment-resistant schizophrenia. Aripiprazole, lurasidone, olanzapine, and risperidone also can be more effective than typical APDs for treatment-resistant schizophrenia; clozapine is uniquely indicated for reducing the risk for suicide. The ability of the atypical APDs to improve cognition and negative symptoms in some patients together with lower propensity to cause tardive dyskinesia (an underappreciated advantage) leads to better overall outcomes. These advantages of the atypical APDs in efficacy and safety are due, in part, to initiation of synaptic plasticity via direct and indirect effects of the atypical APDs on a variety of proteins, especially G proteins, and release of neurotrophins (e.g., brain-derived neurotrophic factor). The typical APDs beneficial effects on psychosis are mainly the result of D₂ receptor blockade, which can be associated with serious side effects and lack of tolerability.

Engineered PLGA microspheres for extended release of brexpiprazole: in vitro and in vivo studies

OBJECTIVE

To develop poly(d,l-lactide-co-glycolide) (PLGA) microspheres to achieve controlled and sustained release of brexpiprazole in vivo.

METHODS

Brexpiprazole microspheres were prepared by oil-in-water emulsion-solvent evaporation method and evaluated for morphology, particle size, encapsulation efficiency, drug loading, conformation and compatibility of drug and polymer, in vitro release, and in vivo pharmacokinetics. By establishing the relationship between in vitro and in vivo release, it helps identify the appropriate in vitro release conditions to explore release profiles of brexpiprazole microspheres.

RESULTS

Porous PLGA microspheres with near spherical morphology were obtained displaying an average diameter of 20.43 ± 0.06 μm, a drug loading capacity of 27.24 ± 0.33% and an encapsulation efficiency of 81.87 ± 1.07%. Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), and differential scanning calorimetry (DSC) analysis showed that some drugs encapsulated in the microspheres remained in the amorphous state and some were in the crystalline state. Different release setups resulted in different release kinetics. The dialysis release setup displayed a cumulative release of about 65% within 60 days, while the sample-and-separate setup showed a cumulative release of about 77% within 35 days. Per pharmacokinetic studies in rats, a burst phase in the plasma concentration-time curve was observed after intramuscular injection in the first 2 h followed by a clear zero-order release phase. Overall, brexpiprazole achieved in vivo sustained release from PLGA microspheres for up to 40 days.

CONCLUSION

A PLGA microsphere loaded with brexpiprazole was successfully developed and demonstrated potential for extended-release of therapeutics for schizophrenia treatment.

Brexpiprazole blocks post-traumatic stress disorder-like memory while promoting normal fear memory

A cardinal feature of post-traumatic stress disorder (PTSD) is a long-lasting paradoxical alteration of memory with hypermnesia for salient traumatic cues and amnesia for peri-traumatic contextual cues. So far, pharmacological therapeutic approach of this stress-related disorder is poorly developed mainly because of the lack of animal model for this paradoxical memory alteration. Using a model that precisely recapitulates the two memory components of PTSD in mice, we tested if brexpiprazole, a new antipsychotic drug with pro-cognitive effects in rodents, may persistently prevent the expression of PTSD-like memory induced by injection of corticosterone immediately after fear conditioning. Acute administration of brexpiprazole (0.3 mg/kg) 7 days' post-trauma first blocks the expression of the maladaptive fear memory for a salient but irrelevant trauma-related cue. In addition, it enhances (with superior efficacy when compared to diazepam, prazosin, and escitalopram) memory for the traumatic context, correct predictor of the threat. This beneficial effect of brexpiprazole is overall maintained 1 week after treatment. In contrast brexpiprazole fully spares normal/adaptive cued fear memory, showing that the effect of this drug is specific to an abnormal/maladaptive (PTSD-like) fear memory of a salient cue. Finally, this treatment not only promotes the switch from PTSD-like to normal fear memory, but also normalizes most of the alterations in the hippocampal-amygdalar network activation associated with PTSD-like memory, as measured by C-Fos expression. Altogether, these preclinical data indicate that brexpiprazole could represent a new pharmacological treatment of PTSD promoting the normalization of traumatic memory.

(Re)contextualizing the Trauma to Prevent or Treat PTSD-Related Hypermnesia

A cardinal feature of Post-traumatic stress-related disorder (PTSD) is a paradoxical memory alteration including both intrusive emotional hypermnesia and declarative/contextual amnesia. Most preclinical, but also numerous clinical, studies focus almost exclusively on the emotional hypermnesia aiming at suppressing this recurrent and highly debilitating symptom either by reducing fear and anxiety or with the ethically questionable idea of a rather radical erasure of traumatic memory. Of very mixed efficacy, often associated with a resurgence of symptoms after a while, these approaches focus on PTSD-related symptom while neglecting the potential cause of this symptom: traumatic amnesia. Two of our preclinical studies have recently demonstrated that treating contextual amnesia durably prevents, and even treats, PTSD-related hypermnesia. Specifically, promoting the contextual memory of the trauma, either by a cognitivo-behavioral, optogenetic or pharmacological approach enhancing a hippocampus-dependent memory processing of the trauma normalizes the fear memory by inducing a long-lasting suppression of the erratic traumatic hypermnesia.

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.

Continuation rate for asenapine and brexpiprazole treatment in patients with schizophrenia

INTRODUCTION

The current study sought to compare the treatment continuation rates of asenapine and brexpiprazole while specifically investigating the factors influencing this index and the clinical efficacy of brexpiprazole.

METHODS

Retrospective study on patients with schizophrenia who were prescribed either asenapine (n = 73) or brexpiprazole (n = 136), as part of their routine medical care.

RESULTS

The treatment continuation rates for asenapine and brexpiprazole were 19.0% and 38.6% at 52 weeks, with that of brexpiprazole found to be significantly higher than that of asenapine (p = .002). Moreover, age was found to be a significant factor affecting the treatment continuation rate for brexpiprazole (p = .03). Additionally, patients with a longer continuation duration had significantly lower Clinical Global Impression-Severity of Illness (CGI-S) scale scores compared to those who discontinued early (p = .04). The continuation rate was also significantly higher for those who began using the drug as outpatients compared to those first administered the drug as inpatients (p = .04). Furthermore, disease duration, CGI-S scale, and continuation duration significantly affected the clinical efficacy of brexipiprazole (p < .05 for all).

CONCLUSIONS

The continuation rate for brexpiprazole increases as the age of the patient increases, as disease severity decreases, and if the patient first uses the drug as an outpatient. Shorter disease duration and longer drug administration may lead to improved clinical efficacy. These results suggest that brexpiprazole is an effective treatment option for maintenance therapy of schizophrenia.

In vitro evaluations for pharmacokinetic drug-drug interactions of a novel serotonin-dopamine activity modulator, brexpiprazole

Brexpiprazole, a serotonin-dopamine activity modulator, is indicated for the treatment of schizophrenia and also adjunctive therapy to antidepressants for the treatment of Major Depressive Disorder. To determine the drug-drug interaction risk for cytochrome P450, and SLC and ABC transporters, brexpiprazole and its metabolite, DM-3411 were assessed in this in vitro investigation.Brexpiprazole exhibited weak inhibitory effects (IC₅₀ >13 μmol/L) on CYP2C9, CYP2C19, CYP2D6 and CYP3A4 activities, but had moderate inhibitor activity on CYP2B6 (IC₅₀ 8.19 μmol/L). The ratio of systemic unbound concentration (3.8 nmol/L) to the K_i value was sufficiently low. DM-3411 had comparable inhibitory potentials with brexpiprazole only for CYP2D6 and CYP3A4. The mRNA expressions of CYP1A2, CYP2B6 and CYP3A4 were not changed by the exposure of brexpiprazole to human hepatocytes.Brexpiprazole and DM-3411 exhibited weak or no inhibitory effects for hepatic and renal transporters (OATPs, OATs, OCTs, MATE1, and BSEP), except for MATE-2K (0.156 μmol/L of DM-3411), even for which the ratio to systemic unbound concentration (5.3 nmol/L) was sufficiently low.Brexpiprazole effected the functions of P-gp and BCRP with IC₅₀ values of 6.31 and 1.16 μmol/L, respectively, however, the pharmacokinetic alteration was not observed in the clinical concomitant study on P-gp and BCRP substrates.These in vitro data suggest that brexpiprazole is unlikely to cause clinically relevant drug interactions resulting from the effects on CYPs or transporters mediating the absorption, metabolism, and/or disposition of co-administered drugs.

Pharmacokinetics and metabolism of brexpiprazole, a novel serotonin-dopamine activity modulator and its main metabolite in rat, monkey and human

The pharmacokinetics of brexpiprazole were investigated in the in vitro and in vivo.The total body clearance of brexpiprazole in rat and monkey was 2.32 and 0.326 L/h/kg, respectively, after intravenous administration, and oral availability was 13.6% and 31.0%, respectively. Dose-dependent exposures were observed at dose ranges between 1-30 mg/kg in the rat and 0.1-3 mg/kg in the monkey.Brexpiprazole distributed widely to body tissues, and V_d,z were 2.81 and 1.82 L/kg in rat and monkey, respectively. The serum protein binding of brexpiprazole was 99% or more in animals and human. Uniform distribution character among the species was suggested by a traditional animal scale-up method.A common main metabolite, DM-3411 was found in animals and humans in the metabolic reactions with the liver S9 fraction. CYP3A4 and CYP2D6 were predominantly involved in the metabolism.The affinity of DM-3411 for D₂ receptors was lower than that of brexpiprazole, and neither DM-3411 nor any metabolites with affinity other than M3 were detected in the brain, demonstrating that brexpiprazole is only involved in the pharmacological effects.Overall, brexpiprazole has a simple pharmacokinetic profile with good metabolic stability, linear kinetics, and no remarkable species differences with regard to metabolism and tissue distribution.

Chronic nicotine, but not suramin or resveratrol, partially remediates the mania-like profile of dopamine transporter knockdown mice

Bipolar disorder (BD) is a severe mental illness affecting 2% of the global population. Current pharmacotherapies provide incomplete symptom remediation, highlighting the need for novel therapeutics. BD is characterized by fluctuations between mania and depression, likely driven by shifts between hyperdopaminergia and hypercholinergia, respectively. Hyperdopaminergia may result from insufficient activity of the dopamine transporter (DAT), the primary mediator of synaptic dopamine clearance. The DAT knockdown (DAT KD) mouse recreates this mechanism and exhibits a highly reproducible hyperexploratory profile in the cross-species translatable Behavioral Pattern Monitor (BPM) that is: (a) consistent with that observed in BD mania patients; and (b) partially normalized by chronic lithium and valproate treatment. The DAT KD/BPM model of mania therefore exhibits high levels of face-, construct-, and predictive-validity for the pre-clinical assessment of putative anti-mania drugs. Three different drug regimens - chronic nicotine (nicotinic acetylcholine receptor (nAChR) agonist; 40 mg/kg/d, 26 d), subchronic suramin (anti-purinergic; 20 mg/kg, 1 × /wk, 4 wks), and subchronic resveratrol (striatal DAT upregulator; 20 mg/kg/d, 4 d) - were administered to separate cohorts of male and female DAT KD- and wildtype (WT) littermate mice, and exploration was assessed in the BPM. Throughout, DAT KD mice exhibited robust hyperexploratory profiles relative to WTs. Nicotine partially normalized this behavior. Resveratrol modestly upregulated DAT expression but did not normalize DAT KD behavior. These results support the mania-like profile of DAT KD mice, which may be partially remediated by nAChR agonists via restoration of disrupted catecholaminergic/cholinergic equilibrium. Delineating the precise mechanism of action of nicotine could identify more selective therapeutic targets.

In situ-gelling starch nanoparticle (SNP)/O-carboxymethyl chitosan (CMCh) nanoparticle network hydrogels for the intranasal delivery of an antipsychotic peptide

Existing oral or injectable antipsychotic drug delivery strategies typically demonstrate low bioavailability to targeted brain regions, incentivizing the development of alternative delivery strategies. Delivery via the nasal cavity circumvents multiple barriers for reaching the brain but requires drug delivery vehicles with very specific properties to be effective. Herein, we report in situ-gelling and degradable bulk nanoparticle network hydrogels consisting of oxidized starch nanoparticles (SNPs) and carboxymethyl chitosan (CMCh) that enable intranasal delivery via spray, high nasal mucosal retention, and functional controlled release of the peptide drug PAOPA, a positive allosteric modulator of dopamine D2 receptor. PAOPA-loaded SNP-CMCh hydrogels can alleviate negative symptoms like behavioural abnormalities associated with schizophrenia (i.e. decreased social interaction time) for up to 72 h in an MK-801-induced pre-clinical rat model of schizophrenia at a low drug dosage (0.5 mg/kg); in comparison, conventional PAOPA administration via the intraperitoneal route requires twice the PAOPA dose to achieve a therapeutic effect that persists for only a few hours. This strategy offers potential for substantially decreasing re-administration frequencies and overall drug doses (and thus side-effects) of a range of potential antipsychotic drugs via a minimally-invasive administration route.

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, Cognitive Impairments and Second-Generation Antipsychotics: From Mechanistic Advances to More Personalized Treatments

The pharmacological treatment of cognitive impairments associated with schizophrenia is still a major unmet clinical need. Indeed, treatments with available antipsychotics generate highly variable cognitive responses among patients with schizophrenia. This has led to the general assumption that antipsychotics are ineffective on cognitive impairment, although personalized medicine and drug repurposing approaches might scale down this clinical issue. In this scenario, evidence suggests that cognitive improvement exerted by old and new atypical antipsychotics depends on dopaminergic mechanisms. Moreover, the newer antipsychotics brexpiprazole and cariprazine, which might have superior clinical efficacy on cognitive deficits over older antipsychotics, mainly target dopamine receptors. It is thus reasonable to assume that despite more than 50 years of elusive efforts to develop novel non-dopaminergic antipsychotics, dopamine receptors remain the most attractive and promising pharmacological targets in this field. In the present review, we discuss preclinical and clinical findings showing dopaminergic mechanisms as key players in the cognitive improvement induced by both atypical antipsychotics and potential antipsychotics. We also emphasize the concept that these mechanistic advances, which help to understand the heterogeneity of cognitive responses to antipsychotics, may properly guide treatment decisions and address the unmet medical need for the management of cognitive impairment associated with schizophrenia.

Effects of 26 Recombinant CYP3A4 Variants on Brexpiprazole Metabolism

As a new atypical antipsychotic, brexpiprazole is primarily metabolized by cytochrome P450 3A4 (CYP3A4). However, genetic polymorphisms in CYP3A4 cause wide variability in individuals' responses to brexpiprazole, leading to unpredictable adverse side effects or even therapeutic failure. The present study was designed to systematically study the effects of 26 recombinant CYP3A4 variants on the metabolism of brexpiprazole and investigate their enzymatic activity. Wild-type CYP3A4 and the 26 variants were incubated with the substrate brexpiprazole for 30 min at 37 °C. The metabolite DM-3411 was detected using ultraperformance liquid chromatography-tandem mass spectrometry. The activity of the wild-type CYP3A4 and 26 of its variants was analyzed. Then, the mechanism underlying the changes in enzyme function was observed using molecular dynamics simulations and molecular docking. Compared with CYP3A4.1, the enzymatic activities of CYP3A4.19, -.24, and -.28 were not significantly different (from 91.82% to 96.25%), but CYP3A4.14 and CYP3A4.15 exhibited higher enzyme activity (from 117.9 to 127.5%). The remaining 21 isoforms, including CYP3A4.2, -.3, -.4, -.5, -.7, -.8, -.9, -.10, -.11, -.12, -.13, -.16, -.17, -.18, -.20, -.23, -.29, -.31, -.32, -.33 and -.34, displayed lower enzymatic activities (from 2.90% to 75.72%). The results obtained from computer modeling indicated that weak binding affinity impaired the function of CYP3A4.32. Mutations that occur around the active site might lead to a loss of enzymatic activity, while the variants located far away from the active site perhaps had little effect on function of CYP3A4. These comprehensive data provide a reference and prediction for treatment strategies and risk assessments of brexpiprazole.

Long-Term Efficacy and Safety of Brexpiprazole in Elderly Japanese Patients with Schizophrenia: A Subgroup Analysis of an Open-Label Study

PURPOSE

This study was performed to assess the long-term efficacy, safety, and tolerability of brexpiprazole in elderly Japanese patients with schizophrenia.

METHODS

This is a post hoc analysis of a previous open-label study conducted over 56 weeks which consisted of two consecutive phases: a 4-week switching period and a 52-week open-label period. Mean change in the Positive and Negative Syndrome Scale (PANSS) total score, response rates, number and incidence of treatment-emergent adverse events (TEAEs), and other safety parameters were analyzed using descriptive statistics based on age group (elderly, ≥65 and non-elderly, <65).

RESULTS

This post hoc analysis included 208 de novo patients of which 33 were elderly. The continuation rate in elderly patients was 54.5%, and the mean daily dose and treatment duration of brexpiprazole in elderly patients at week 56 were similar to those of non-elderly patients. The mean change in the PANSS total score from the baseline to week 56 was -13.8 in elderly patients and this improvement was maintained throughout the open-label phase. This outcome was comparable to that of the non-elderly patients (-9.0). The incidence rate of TEAEs was 97.0% in elderly patients and 82.3% in non-elderly patients. Most of the TEAEs were either mild (75.8%) or moderate (18.2%) in severity in the elderly patients and the incidence of TEAEs leading to discontinuation was lower in elderly (9.1%) than in non-elderly patients (13.1%). The most commonly observed adverse events in elderly patients were nasopharyngitis (30.3%) and worsening of schizophrenia (27.3%). The safety profiles in both groups were similar.

CONCLUSION

Brexpiprazole was shown to be safe and effective in the treatment of elderly Japanese patients with schizophrenia.

Real-World Economic Outcomes of Brexpiprazole and Extended-Release Quetiapine Adjunctive Use in Major Depressive Disorder

Purpose

Major depressive disorder (MDD) is a chronic mental disorder with a substantial clinical and economic burden. Despite the efficacy of adjunctive atypical antipsychotics (AAP) for augmentation in patients with major depressive disorder (MDD) who failed first-line antidepressant therapy (ADT), little is known of the impact of AAP choices on healthcare resource use and costs in real-world practice. Therefore, this study compared real-world healthcare utilization and costs in patients with MDD treated with brexpiprazole or extended-release (XR) quetiapine as adjunctive treatment to ADT.

Patients and methods

Adults with MDD starting adjunctive treatment with brexpiprazole (n=844) or extended-release (XR) quetiapine (n=688) were identified in the adjudicated health plan claims data (07/2014 – 09/2016). Resource use and healthcare costs in the 6 months following treatment initiation were compared between non-matched populations, and between propensity score-matched groups, and by multivariable regression analyses.

Results

During follow-up, unadjusted all-cause hospitalization (6.6% vs 12.5%) and ED visits (17.0% vs 27.5%) were lower with brexpiprazole compared to quetiapine XR (both p<0.001). Brexpiprazole-treated patients had significantly lower mean medical costs (US$6,421 vs US$8,545, p=0.0123) but higher mean pharmacy costs (US$7,401 vs US$4,691, p<0.0001) than quetiapine XR-treated patients did. Total healthcare costs were not significantly different between the two cohorts. Propensity score-matched comparisons of 397 patients in each cohort showed no statistically significant difference in all-cause hospitalization, ED visits, and total healthcare costs; and significantly lower medical costs (US$5,719 vs US$8,602, p=0.0092) but higher pharmacy costs (US$7,091 vs US$5,091, p=0.0007) in brexpiprazole compared to quetiapine XR. In multivariable regressions, brexpiprazole was associated with 16.1% lower medical costs (p=0.0186) and 9.4% higher total healthcare costs (p=0.0463) as compared to quetiapine XR.

Conclusion

Significantly lower medical costs were observed in patients with MDD treated with brexpiprazole vs quetiapine XR.

[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.

Novel antipsychotics specificity profile: A clinically oriented review of lurasidone, brexpiprazole, cariprazine and lumateperone

Second generation antipsychotics (SGAs) are effective options in the treatment of schizophrenia and mood disorders, each with characteristic efficacy and safety features. In order to optimize the balance between efficacy and side effects, it is of upmost importance to match compound specificity against patient clinical profile. As the number of SGAs increased, this review can assist physicians in the prescription of three novel SGAs already on the market, namely lurasidone, brexpiprazole, cariprazine, and lumateperone, which is in the approval phase for schizophrenia treatment at the FDA. Besides schizophrenia, EMA and/or FDA approved lurasidone for bipolar depression, brexpiprazole as augmentation in major depressive disorder and cariprazine for the acute treatment of manic or mixed episodes associated with bipolar I disorder. These new antipsychotics were developed with the aim of improving efficacy on negative and depressive symptoms and reducing metabolic and cardiovascular side effects compared to prior SGAs, while keeping the risk of extrapyramidal symptoms low. They succeeded quite well in containing these side effects, despite weight gain during acute treatment remains a possible concern for brexpiprazole, while cariprazine and lurasidone show higher risk of akathisia compared to placebo and other SGAs such as olanzapine. The available studies support the expected benefits on negative symptoms, cognitive dysfunction and depressive symptoms, while the overall effect on acute psychotic symptoms may be similar to other SGAs such as quetiapine, aripiprazole and ziprasidone. The discussed new antipsychotics represent useful therapeutic options but their efficacy and side effect profiles should be considered to personalize prescription.

Advances in Management of Neuropsychiatric Syndromes in Neurodegenerative Diseases

PURPOSE OF REVIEW

Neuropsychiatric syndromes (NPS) are common in neurodegenerative disorders (NDD). This review describes the role of NPS in the diagnosis of NDD, criteria for the diagnosis of NPS, management of NPS, and agents in clinical trials for NPS.

RECENT FINDINGS

NPS play an increasingly important role in the diagnosis of NDD. Consensus diagnostic criteria have evolved for psychosis, depression, agitation, and apathy in NDD. With one exception-pimavanserin is approved for the treatment of hallucinations and delusions in Parkinson's disease-there are no drugs approved by the FDA for treatment of NPS in NDD. Trials show that atypical antipsychotics reduce psychosis in AD and in Parkinson's disease, although side effect concerns have constrained their use. Antidepressants show benefit in treatment of Parkinson's disease with depression. Several agents are in clinical trials for treatment of NPS in NDD. Neuropsychiatric syndromes play a major role in NDD diagnosis. Clinical criteria allow recognition of NPS in NDD. Psychotropic medications are often useful in the treatment of NPS in NDD; efficacious, safe, and approved agents are needed.

Co-treatment of buspirone with atypical antipsychotic drugs (AAPDs) improved neurocognitive function in chronic schizophrenia

We conducted a 24-week, randomized, double-blind parallel-controlled trial to test whether buspirone is beneficial to improve cognitive deficits of schizophrenia because it remains unclear. Two hundred patients received in random order either co-treatment buspirone with AAPDs or monotherapy with AAPDs. All patients had been treated with a stable dosage of AAPDs for at least three months. The positive and negative syndrome scale (PANSS), Hamilton Depression Scale-24 (HAMD-24), and 14-item Hamilton Rating Scale for Anxiety (HAMA-14) were used to evaluate clinical symptoms. The short version of Wechsler Adult Intelligence Scale-Revised in China (WAIS-RC) was used to assess neurocognitive function. Social function and family burden were evaluated by Social Disability Screening Schedule (SDSS) and Family Burden Interview Schedule (FBIS). All patients were enrolled at baseline and followed up after 12 and 24 weeks. A total of 196 patients completed the trial, with 99 in the combined treatment group and 97 in the control group. During the intervention, the score of PANSS, HAMD-24, and HAMA-14 decreased slightly without group differences. Repeated measures ANOVA showed significant differences between the two groups in the score of arithmetic, similarities, picture completion, block design, SDSS, and FBIS (P < 0.05), but no difference was found with regard to the score of information, digital span test, or digital symbols (P > 0.05). In conclusion, co-treatment with buspirone and APPDs outperformed APPDs alone in improving cognitive deficit and reducing family burden of schizophrenia. Buspirone may be a promising candidate for co-treatment of schizophrenia-associated cognitive deficits.

Brexpiprazole: A Review in Schizophrenia

Brexpiprazole (Rxulti^®, Rexulti^®) is an oral atypical antipsychotic agent approved for the treatment of schizophrenia in the EU (in adult patients) and the USA, as well as in some other countries, including Japan. Like aripiprazole, it is a partial agonist at dopamine D₂ and serotonin 5-HT_1A receptors and an antagonist at serotonin 5-HT_2A receptors. However, brexpiprazole displays less intrinsic activity at D₂ receptors and, coupled with actions at 5HT_1A, 5HT_2A and noradrenaline α_1B receptors that are at least as potent as its action at D₂ receptors, is predicted to demonstrate a lower propensity for activating adverse events and extrapyramidal symptoms than aripiprazole. Brexpiprazole 2-4 mg/day produced statistically significant and clinically meaningful improvements in overall symptomatology and psychosocial functioning compared with placebo in adults with acute exacerbation of schizophrenia. As maintenance treatment, brexpiprazole 1-4 mg/day significantly delayed the time to relapse compared with placebo in patients who were already stabilized on the drug and was associated with stabilization or continued improvement in patients' symptoms and functioning. Brexpiprazole was generally well tolerated, exhibiting an adverse event profile characterized by a relatively low incidence of activating and sedating adverse effects, small changes in QT interval and metabolic parameters that were not clinically significant, and moderate weight gain. Clinical evidence to date suggests it usefully extends the range of therapeutic options for schizophrenia.

A Review of the Pharmacological and Clinical Profile of Newer Atypical Antipsychotics as Treatments for Bipolar Disorder: Considerations for Use in Older Patients

Bipolar disorder prevalence rates vary in the older adult population (defined as age ≥ 65 years), ranging from 1% in community dwellers to as high as 8-10% in hospital inpatients. Although older agents, including lithium and valproic acid, offer significant antimanic efficacy, as supported by a recent randomized controlled trial (RCT), there is growing interest in using atypical antipsychotics to treat bipolar disorder in older adults. Newer atypical antipsychotics are of interest based on their tolerability and efficacy in the general adult bipolar population. The aim of this review was to systematically examine efficacy and tolerability of newer atypical antipsychotics for older adult bipolar disorder (OABD). We conducted a systematic search utilizing the MEDLINE, EMBASE, PsycINFO and Cochrane Library electronic databases, with the aim of identifying all RCTs comparing newer atypical antipsychotics approved by the US FDA since 2002 (including brexpiprazole, cariprazine, lurasidone, iloperidone, asenapine, paliperidone, and aripiprazole) with placebo or another comparator, in the treatment of any phase of bipolar disorder (including mania, depression or mixed episodes while used as an acute or maintenance treatment) in older adults (> 65 years). We found no RCT data on any of the examined agents. Hence, we changed our search criteria to include studies with a lower age cut-off (≥ 55 years), as well as the inclusion of post hoc studies. Two post hoc studies on lurasidone suggest its reasonable safety and efficacy profile in the acute and maintenance treatment of OABD; however, there are no pharmacoeconomic data on the use of lurasidone in the treatment of OABD. Research data from open-label studies on oral asenapine and aripiprazole as add-on therapy suggest that these two agents are adequately tolerated and improved symptoms of depression and mania in OABD; hence, there is an urgent need to conduct RCTs on these two agents. Lastly, we found no studies for the treatment of OABD with brexpiprazole, cariprazine, iloperidone, or paliperidone.

Current Concepts and Treatments of Schizophrenia

Schizophrenia is a debilitating mental illness which involves three groups of symptoms, i.e., positive, negative and cognitive, and has major public health implications. According to various sources, it affects up to 1% of the population. The pathomechanism of schizophrenia is not fully understood and current antipsychotics are characterized by severe limitations. Firstly, these treatments are efficient for about half of patients only. Secondly, they ameliorate mainly positive symptoms (e.g., hallucinations and thought disorders which are the core of the disease) but negative (e.g., flat affect and social withdrawal) and cognitive (e.g., learning and attention disorders) symptoms remain untreated. Thirdly, they involve severe neurological and metabolic side effects and may lead to sexual dysfunction or agranulocytosis (clozapine). It is generally agreed that the interactions of antipsychotics with various neurotransmitter receptors are responsible for their effects to treat schizophrenia symptoms. In particular, several G protein-coupled receptors (GPCRs), mainly dopamine, serotonin and adrenaline receptors, are traditional molecular targets for antipsychotics. Comprehensive research on GPCRs resulted in the exploration of novel important signaling mechanisms of GPCRs which are crucial for drug discovery: intentionally non-selective multi-target compounds, allosteric modulators, functionally selective compounds and receptor oligomerization. In this review, we cover current hypotheses of schizophrenia, involving different neurotransmitter systems, discuss available treatments and present novel concepts in schizophrenia and its treatment, involving mainly novel mechanisms of GPCRs signaling.

In Vitro and In Vivo Characterization of PCC0104005, a Novel Modulator of Serotonin-Dopamine Activity, as an Atypical Antipsychotic Drug

PCC0104005 is a novel drug candidate for treating schizophrenia that displays high affinity for serotonin, dopamine, and noradrenaline receptors, including partial agonism at dopamine D₂, D₃, D₄, serotonin 5-HT_1A, and 5-HT_2A receptors and antagonism at 5-HT_2B, 5-HT₆, and 5-HT₇ receptors. PCC0104005 blocks MK-801-induced hyperactivity in rats, consistent with the reduction in dopamine D₂ receptor stimulation and increased dopamine release in the medial prefrontal cortex. PCC0104005 inhibits 5-HTP-induced head twitches in rats, due to its moderate affinity for human 5-HT_2A receptors (Ki = 5.1 nM). PCC0104005 significantly reduced the escape latency of rats and improved the MK-801-induced memory impairment. In the object recognition experiment, PCC0104005 significantly improved the recognition disorder induced by MK-801. PCC0104005 did not significantly increase the plasma prolactin level, which is thought to be related to the preferential affinity of PCC0104005 for dopamine D₂ receptors compared with 5-HT_1A receptors, as well as the relative antagonistic activity toward the D₂ receptor. Due to its 5-HT_1A agonism, PCC0104005 does not produce catalepsy in mice, a behaviour predictive of the occurrence of extra-pyramidal syndrome (EPS) in humans. PCC0104005 has unique affinities for dopamine receptors and serotonin receptors, which may lead to clinical advantages, as well as fewer adverse reactions.

Vortioxetine Treatment Reverses Subchronic PCP Treatment-Induced Cognitive Impairments: A Potential Role for Serotonin Receptor-Mediated Regulation of GABA Neurotransmission

Major depressive disorder (MDD) is associated with cognitive impairments that may contribute to poor functional outcomes. Clinical data suggests that the multimodal antidepressant vortioxetine attenuates some cognitive impairments in MDD patients, but the mechanistic basis for these improvements is unclear. One theory suggests that vortioxetine improves cognition by suppressing γ-amino butyric acid (GABA)ergic neurotransmission, thereby increasing glutamatergic activation. Vortioxetine’s effects on cognition, GABA and glutamate neurotransmission have been supported in separate experiments, but no empirical work has directly connected vortioxetine’s cognitive effects to those on GABA and glutamate neurotransmission. In this paper, we attempt to bridge this gap by evaluating vortioxetine’s effects in the subchronic PCP (subPCP) model, which induces impaired cognitive function and altered GABA and glutamate neurotransmission. We demonstrate that acute or subchronic vortioxetine treatment attenuated subPCP-induced deficits in attentional set shifting (AST) performance, and that the selective 5-HT₃ receptor antagonist ondansetron or the 5-HT reuptake inhibitor escitalopram could mimic this effect. Furthermore, acute vortioxetine treatment reversed subPCP-induced object recognition (OR) deficits in rats, while subchronic vortioxetine reversed subPCP-induced Object Recognition and object placement impairments in mice. Finally, subPCP treatment reduced GABA_B receptor expression in a manner that was insensitive to vortioxetine treatment, and subchronic vortioxetine treatment alone, but not in combination with subPCP, significantly increased GABA’s affinity for the GABA_A receptor. These data suggest that vortioxetine reverses cognitive impairments in a model associated with altered GABA and glutamate neurotransmission, further supporting the hypothesis that vortioxetine’s GABAergic and glutamatergic effects are relevant for cognitive function.

Adjunctive treatment with brexpiprazole and escitalopram reduces behavioral stress responses and increase hypothalamic NPY immunoreactivity in a rat model of PTSD-like symptoms

The study explored effects of brexpiprazole (partial D₂/5-HT_1A agonist, 5-HT_2A and α_1B/2C-adrenoceptor antagonist) in rats exposed to predator scent stress (PSS), a proposed model of PTSD-like phenotype. Brexpiprazole (3.0mg/kg, PO), escitalopram (5.0mg/kg, IP) and their combination were administered twice daily for 14 days, starting 14 days after exposure to PSS or sham-PSS, shortly after a situational stress reminder. One day after last treatment behavioral responsivity was assessed. Brexpiprazole+escitalopram-treated rats spent more time in open arms, entered open arms more often and exhibited a lower anxiety index in the elevated plus maze than vehicle-treated, PSS-exposed rats. Adjunct brexpiprazole+escitalopram treatment reduced startle amplitude, compared with vehicle-treated, PSS-exposed rats. Treatment with either drug alone did not attenuate anxiety-like behaviors following PSS exposure. Use of cut-off behavioral criteria confirmed that adjunct treatment shifted prevalence of PSS-exposed rats from extreme towards minimal behavioral responders. One day following behavioral tests, brains were prepared for immunohistochemical analysis of number of BDNF-positive cells and of NPY-positive cells/fibers. PSS exposure decreased BDNF levels in hippocampus, but this was not affected by drug treatments. PSS exposure decreased number of NPY positive cells/fibers in paraventricular and arcuate nuclei of hypothalamus. Adjunct treatment with brexpiprazole+escitalopram increased NPY in PSS- and sham-exposed rats. Treatment with brexpiprazole alone had no effects, while treatment with escitalopram alone increased NPY in the arcuate nucleus of PSS-exposed rats. In conclusion, treatment with brexpiprazole+escitalopram may be an effective intervention for the attenuation of PTSD-like stress responses, which in part may be mediated by activating NPY function.

The antipsychotic drug brexpiprazole reverses phencyclidine-induced disruptions of thalamocortical networks

Brexpiprazole (BREX), a recently approved antipsychotic drug in the US and Canada, improves cognitive dysfunction in animal models, by still largely unknown mechanisms. BREX is a partial agonist at 5-HT_1A and D₂ receptors and antagonist at α_1B- and α_2C-adrenergic and 5-HT_2A receptors all with a similar potency. The NMDA receptor antagonist phencyclidine (PCP), used as pharmacological model of schizophrenia, activates thalamocortical networks and decreases low frequency oscillations (LFO; <4 Hz). These effects are reversed by antipsychotics. Here we assessed the ability of BREX to reverse PCP-induced hyperactivity of thalamocortical circuits, and the involvement of 5-HT_1A receptors in its therapeutic action. BREX reversed PCP-induced neuronal activation at a lower dose in centromedial/mediodorsal thalamic nuclei (CM/MD; 0.5mg/kg) than in pyramidal medial prefrontal cortex neurons (mPFC, 2mg/kg), perhaps due to antagonism at α_1B-adrenoceptors, abundantly expressed in the thalamus. Conversely, a cumulative 0.5 mg/kg dose reversed a PCP-induced LFO decrease in mPFC but not in CM/MD. BREX reduced LFO in both areas, yet with a different dose-response, and moderately excited mPFC neurons. The latter effect was reversed by the 5-HT_1A receptor antagonist WAY-100635. Thus, BREX partly antagonizes PCP-induced thalamocortical hyperactivity, differentially in mPFC versus CM/MD. This regional selectivity may be related to the differential expression of α_1B-, α_2C-adrenergic and 5-HT_2A receptors in both regions and/or different neuronal types. Furthermore, the pro-cognitive properties of BREX may be related to the 5-HT_1A receptor-mediated increase in mPFC pyramidal neuron activity. Overall, the present data provide new insight on the brain elements involved in BREX's therapeutic actions.

Alterations in amino acid levels in mouse brain regions after adjunctive treatment of brexpiprazole with fluoxetine: comparison with (R)-ketamine

RATIONALE

Brexpiprazole, a serotonin-dopamine activity modulator, is approved in the USA as an adjunctive therapy to antidepressants for treating major depressive disorders. Similar to the N-methyl-D-aspartate receptor (NMDAR) antagonist ketamine, the combination of brexpiprazole and fluoxetine has demonstrated antidepressant-like effects in animal models of depression.

OBJECTIVES

The present study was conducted to examine whether the combination of brexpiprazole and fluoxetine could affect the tissue levels of amino acids [glutamate, glutamine, γ-aminobutyric acid (GABA), D-serine, L-serine, and glycine] that are associated with NMDAR neurotransmission.

METHODS

The tissue levels of amino acids in the frontal cortex, striatum, hippocampus, and cerebellum were measured after a single [or repeated (14 days)] oral administration of vehicle, fluoxetine (10 mg/kg), brexpiprazole (0.1 mg/kg), or a combination of the two drugs. Furthermore, we measured the tissue levels of amino acids after a single administration of the NMDAR antagonist (R)-ketamine.

RESULTS

A single injection of the combination of fluoxetine and brexpiprazole significantly increased GABA levels in the striatum, the D-serine/L-serine ratio in the frontal cortex, and the glycine/L-serine ratio in the hippocampus. A repeated administration of the combination significantly altered the tissue levels of amino acids in all regions. Interestingly, a repeated administration of the combination significantly decreased the D-serine/L-serine ratio in the frontal cortex, striatum, and hippocampus. In contrast, a single administration of (R)-ketamine significantly increased the D-serine/L-serine ratio in the frontal cortex.

CONCLUSIONS

These results suggested that alterations in the tissue levels of these amino acids may be involved in the antidepressant-like effects of the combination of brexpiprazole and fluoxetine.

Buspirone Counteracts MK-801-Induced Schizophrenia-Like Phenotypes through Dopamine D3 Receptor Blockade

Background: Several efforts have been made to develop effective antipsychotic drugs. Currently, available antipsychotics are effective on positive symptoms, less on negative symptoms, but not on cognitive impairment, a clinically relevant dimension of schizophrenia. Drug repurposing offers great advantages over the long-lasting, risky and expensive, de novo drug discovery strategy. To our knowledge, the possible antipsychotic properties of buspirone, an azapirone anxiolytic drug marketed in 1986 as serotonin 5-HT_1A receptor (5-HT_1AR) partial agonist, have not been extensively investigated despite its intriguing pharmacodynamic profile, which includes dopamine D₃ (D₃R) and D₄ receptor (D₄R) antagonist activity. Multiple lines of evidence point to D₃R as a valid therapeutic target for the treatment of several neuropsychiatric disorders including schizophrenia. In the present study, we tested the hypothesis that buspirone, behaving as dopamine D₃R antagonist, may have antipsychotic-like activity.

Materials and Methods: Effects of acute administration of buspirone was assessed on a wide-range of schizophrenia-relevant abnormalities induced by a single administration of the non-competitive NMDAR antagonist MK-801, in both wild-type mice (WT) and D₃R-null mutant mice (D₃R^-/-).

Results: Buspirone (3 mg⋅kg^-1, i.p.) was devoid of cataleptogenic activity in itself, but resulted effective in counteracting disruption of prepulse inhibition (PPI), hyperlocomotion and deficit of temporal order recognition memory (TOR) induced by MK-801 (0.1 mg⋅kg^-1, i.p.) in WT mice. Conversely, in D₃R^-/- mice, buspirone was ineffective in preventing MK-801-induced TOR deficit and it was only partially effective in blocking MK-801-stimulated hyperlocomotion.

Conclusion: Taken together, these results indicate, for the first time, that buspirone, might be a potential therapeutic medication for the treatment of schizophrenia. In particular, buspirone, through its D₃R antagonist activity, may be a useful tool for improving the treatment of cognitive deficits in schizophrenia that still represents an unmet need of this disease.

Brexpiprazole in patients with schizophrenia: overview of short- and long-term phase 3 controlled studies

OBJECTIVE

Review efficacy, safety, and tolerability of brexpiprazole in patients with schizophrenia in short- and long-term phase 3 studies.

METHODS

Patients experiencing a current exacerbation of schizophrenia received brexpiprazole in two fixed-dose (2 and 4 mg), 6-week, placebo-controlled studies, one flexible-dose (2-4 mg), 6-week, placebo-control and active reference study, and one fixed-dose (1-4 mg), 52-week, placebo-controlled maintenance study.

RESULTS

The efficacy of brexpiprazole was demonstrated in the two short-term fixed-dose studies with statistically significant improvements from baseline in Positive and Negative Syndrome Scale (PANSS) total score compared with placebo. In the flexible-dose short-term study, treatment with brexpiprazole resulted in numerically greater improvements in PANSS total score than with placebo that approached statistical significance (p=0.056). A meta-analysis of these short-term studies showed a mean change in PANSS total score of -20.1, reflecting a clinically meaningful reduction in symptoms. In the maintenance study, brexpiprazole had a beneficial effect relative to placebo on time to exacerbation of psychotic symptoms/impending relapse (p<0.0001). For all studies, brexpiprazole demonstrated clinically meaningful treatment effects on the Personal and Social Performance scale. Brexpiprazole had a favourable safety profile, with a relatively low prevalence of activating and sedating side effects. Weight gain in the short-term studies was ~1 kg greater than placebo. No safety concerns were observed with brexpiprazole in laboratory values, electrocardiogram, or vital signs.

CONCLUSIONS

Overall, the results indicate brexpiprazole, used either short-term or as part of a long-term maintenance treatment programme, is an efficacious therapy option in adults with schizophrenia and has a favourable safety/tolerability profile.