Brexpiprazole for the maintenance treatment of adults with schizophrenia: an evidence-based review and place in therapy

A review on the pharmacology of cariprazine and its role in the treatment of negative symptoms of schizophrenia

Management of negative symptoms is one of the most challenging and important unmet needs of schizophrenia treatment. Negative symptoms together with positive symptoms result in significant psychosocial impairment and poor quality of life. Existing studies on atypical antipsychotics reported limited treatment adherence due to higher prevalence of treatment-emergent adverse events, such as diabetes, weight gain, hyperlipidemia, hyperprolactinemia and hypertension. A compound with greater affinity for dopamine D2/D3 receptors may improve negative symptoms, mood, and cognitive impairment associated with schizophrenia. In 2015, the US FDA has approved cariprazine, a partial D2/D3 agonist for treatment of schizophrenia, mania or mixed episodes. Midlands and Lancashire Commissioning Support Unit, UK (2019) has particularly suggested cariprazine for the treatment of predominant negative symptoms of schizophrenia. India's Central Drugs Standard Control Organization (CDSCO) has approved cariprazine in 2021 for the treatment of schizophrenia, manic or mixed episodes associated with bipolar I disorder. A ten-fold greater affinity for D3 receptors and partial agonism to serotonin receptors, along with longer half-life make cariprazine distinct when compared with other atypical antipsychotics. Cariprazine is also reported to have fewer incidents of metabolic and hormonal adverse events, and has been shown to provide better relapse prevention. Recent evidence indicates promising effect of cariprazine in ameliorating negative symptoms as well as psychotic symptoms in patients with schizophrenia. In addition, improved adherence to treatment (adjunctive/monotherapy) with cariprazine in patients having inadequate response to an ongoing antipsychotic treatment has also been clinically established. This review presents the evidence-based safety and efficacy of cariprazine for treatment of predominant negative symptoms of schizophrenia.

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.

New Antipsychotic Medications in the Last Decade

PURPOSE OF REVIEW

Over the last ten years, the treatment of psychosis has seen a near explosion of creative development in both novel agents and new delivery modalities. The current review summarizes these developments over the past decade (2011-2020). We performed a systematic review utilizing PubMed and PsychInfo with the aim of identifying all the RCT and related analyses in adults with psychosis (schizophrenia and mania).

RECENT FINDINGS

We identified 11 significant developments: the introduction of new antipsychotics cariprazine, brexpiprazole, lumateperone, and pimavanserin; introduction of new delivery methods: subcutaneous long-acting risperidone, aripiprazole lauroxil, transdermal asenapine, and inhaled loxapine; and the introduction of new approaches such as olanzapine/samidorphan for olanzapine-associated weight gain, examination of the TAAR1 agonist SEP 363,856 as a test of concept, and the combination of Xanomeline/Trospium, an M₁ and M₄ muscarinic receptor agonist in conjunction with a peripheral anticholinergic. Last decade has seen a tremendous development in second-generation antipsychotics which provides unprecedented treatment options for clinicians in treating psychosis.

Partial agonists of dopamine receptors: mechanisms and clinical effects of aripiprazole, brexpiprazole and cariprazine

Aripiprazole, brexpiprazole and cariprazine are partial dopamine (and serotonin) agonists developed as novel antipsychotics. This article discusses their pharmacology, evidence on their licensed and off-licence uses (including psychosis, mania, bipolar depression, Tourette syndrome and autism spectrum disorder) and side-effects. In schizophrenia, they have a low risk of Parkinsonism or hyperprolactinaemia, cause modest increases in body weight and are of moderate efficacy.

Effect of Novel Antipsychotics on Energy Metabolism - In Vitro Study in Pig Brain Mitochondria

The identification and quantification of mitochondrial effects of novel antipsychotics (brexpiprazole, cariprazine, loxapine, and lurasidone) were studied in vitro in pig brain mitochondria. Selected parameters of mitochondrial metabolism, electron transport chain (ETC) complexes, citrate synthase (CS), malate dehydrogenase (MDH), monoamine oxidase (MAO), mitochondrial respiration, and total ATP and reactive oxygen species (ROS) production were evaluated and associated with possible adverse effects of drugs. All tested antipsychotics decreased the ETC activities (except for complex IV, which increased in activity after brexpiprazole and loxapine addition). Both complex I- and complex II-linked respiration were dose-dependently inhibited, and significant correlations were found between complex I-linked respiration and both complex I activity (positive correlation) and complex IV activity (negative correlation). All drugs significantly decreased mitochondrial ATP production at higher concentrations. Hydrogen peroxide production was significantly increased at 10 µM brexpiprazole and lurasidone and at 100 µM cariprazine and loxapine. All antipsychotics acted as partial inhibitors of MAO-A, brexpiprazole and loxapine partially inhibited MAO-B. Based on our results, novel antipsychotics probably lacked oxygen uncoupling properties. The mitochondrial effects of novel antipsychotics might contribute on their adverse effects, which are mostly related to decreased ATP production and increased ROS production, while MAO-A inhibition might contribute to their antidepressant effect, and brexpiprazole- and loxapine-induced MAO-B inhibition might likely promote neuroplasticity and neuroprotection. The assessment of drug-induced mitochondrial dysfunctions is important in development of new drugs as well as in the understanding of molecular mechanism of adverse or side drug effects.

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.

Regulation of Reactive Oxygen Species-Mediated Damage in the Pathogenesis of Schizophrenia

The biochemical integrity of the brain is paramount to the function of the central nervous system, and oxidative stress is a key contributor to cerebral biochemical impairment. Oxidative stress, which occurs when an imbalance arises between the production of reactive oxygen species (ROS) and the efficacy of the antioxidant defense mechanism, is believed to play a role in the pathophysiology of various brain disorders. One such disorder, schizophrenia, not only causes lifelong disability but also induces severe emotional distress; however, because of its onset in early adolescence or adulthood and its progressive development, consuming natural antioxidant products may help regulate the pathogenesis of schizophrenia. Therefore, elucidating the functions of ROS and dietary antioxidants in the pathogenesis of schizophrenia could help formulate improved therapeutic strategies for its prevention and treatment. This review focuses specifically on the roles of ROS and oxidative damage in the pathophysiology of schizophrenia, as well as the effects of nutrition, antipsychotic use, cognitive therapies, and quality of life on patients with schizophrenia. By improving our understanding of the effects of various nutrients on schizophrenia, it may become possible to develop nutritional strategies and supplements to treat the disorder, alleviate its symptoms, and facilitate long-term recovery.

Antipsychotic-induced Hyperprolactinemia in aging populations: Prevalence, implications, prevention and management

This paper reviews the prevalence, implications, prevention and management of antipsychotic-induced hyperprolactinemia in aging populations. Antipsychotics are indicated mainly for the treatment of psychotic illness but are also used in other conditions. Complications induced by antipsychotics increase with age, due to age-related changes in drug metabolism and excretion. Almost all antipsychotics lead to hyperprolactinemia by blocking dopamine D2 receptors in the anterior pituitary gland, which counteracts dopamine's inhibitory action on prolactin secretion. The main findings of this narrative review are that, though many of the known side effects of high prolactin levels lose their salience with age, the risk of exacerbating osteoporosis remains critical. Methods of preventing antipsychotic-induced hyperprolactinemia in older individuals include using antipsychotic medication (AP) as sparingly as possible and monitoring AP serum levels, regularly measuring prolactin levels, closely monitoring bone density, treating substance abuse, and teaching patients stress management techniques. When hyperprolactinemia symptoms cannot be otherwise managed, adjunctive drugs are available. Potential helpful adjuncts are: dopamine agonists, antipsychotics with partial agonist properties (e.g. aripiprazole), selective estrogen receptor modulators, and metformin. Because a gold standard for prevention/treatment has not been established, clinical decisions need to be made based on safety and individual circumstance.

New antipsychotic drugs for the treatment of agitation and psychosis in Alzheimer's disease: focus on brexpiprazole and pimavanserin

Behavioral and psychological symptoms of dementia are symptoms of disturbed perception, mood, behavior, and thought content that occurred frequently. These symptoms, which include apathy, depression, anxiety, psychosis, agitation, and aggression, can serve as predictors of and early clinical diagnostic markers for Alzheimer's disease (AD) and are common precipitants of institutional care. Agitation and psychosis are associated with accelerated disease progression and increased tau phosphorylation in patients with AD. Current guidelines recommend the use of second-generation antipsychotics for the treatment of agitation and psychosis in AD, but only after first-line non-pharmacological interventions and for no longer than 12 weeks because long-term use of these drugs is associated with an increased risk of mortality and an increased frequency of cerebrovascular events. Therefore, new antipsychotic drugs with improved efficacy and safety are needed as an alternative to current antipsychotic drugs. In this report, we discuss some of the most relevant advances in the field of agitation and psychosis in AD and focus on the recent positive clinical evidence observed with two new antipsychotics drugs: brexpiprazole and pimavanserin. Brexpiprazole is a receptor partial agonist (D2, D3, 5-HT1A), receptor antagonist (5-HT2A/B, α1B/α2C) according to the neuroscience-based nomenclature. Two recent phase III clinical trials have shown that brexpiprazole 2 mg/day is effective for the treatment of agitation in patients with AD and has an improved tolerability and safety profile compared with currently available second-generation antipsychotics. Pimavanserin is a receptor antagonist (5-HT2A, 5-HT2C) that has been given market authorization for psychosis occurring in Parkinson's disease. Recent phase II studies suggest that this drug is effective in AD patients with more severe psychosis, although further long-term studies are needed to better define the efficacy and long-term safety profile of pimavanserin for the treatment of psychosis in AD.

Brexpiprazole in the treatment of schizophrenia and agitation in Alzheimer's disease

Schizophrenia is a disabling psychiatric disorder marked by progressive loss of functionality in activities of daily living with each relapse. Antipsychotics, the mainstay of therapy for schizophrenia, treat hallucinations and delusions but may have intolerable side effects, including metabolic disturbances and extrapyramidal symptoms. Brexpiprazole, a second-generation antipsychotic with dopamine partial agonist properties, was approved by the US FDA in 2015 for the treatment of schizophrenia and adjunctive treatment of major depressive disorder and by the EU in 2018 for adults with schizophrenia. Additionally, brexpiprazole has recently been studied for the treatment of agitation in Alzheimer's dementia, an area of largely unmet need. Overall, well-tolerated brexpiprazole expands the armamentarium of treatment options available for these conditions.

Comparative Tolerability of Dopamine D2/3 Receptor Partial Agonists for Schizophrenia

Aripiprazole, brexpiprazole and cariprazine differ from all other second-generation antipsychotics due to partial agonism at the dopamine D2 and D3 receptors. In contrast to aripiprazole, brexpiprazole has lower intrinsic dopamine D2 activity and higher affinity for the serotonin 5-HT1A and 5-HT2A receptors, while cariprazine has the highest affinity for the dopamine D3 receptor, and the longest half-life. The main adverse effect of dopamine receptor partial agonists (DRPAs) is akathisia of low-to-moderate severity, which occurs in a small proportion of patients, usually in the first few weeks of treatment. While definitive conclusions concerning differences between the DRPAs require head-to-head comparison studies, on the available evidence, akathisia is probably least likely to occur with brexpiprazole and most likely with cariprazine; the risk of akathisia with aripiprazole lies in between. Weight-gain risk is low with aripiprazole and cariprazine, but moderate with brexpiprazole. Risk of sedation is low with DRPAs, as is risk of insomnia and nausea. Partial dopamine agonism leads to a low risk for hyperprolactinaemia (and probably a low risk of sexual dysfunction). Prolactin concentrations fall in some patients (particularly those with elevated levels prior to initiating the drugs). Rates of discontinuation due to adverse effects in pivotal studies were low, and on the whole, DRPAs are well tolerated. Aripiprazole has been implicated in pathological gambling and other impulse control behaviours, likely due to partial dopamine agonist activity (there have been no reports with brexpiprazole and cariprazine). The risks for diabetes and tardive dyskinesia with DRPAs are unknown, but are likely to be low. On the basis of tolerability, DRPAs should be considered as first-line treatment options, particularly in patients with early schizophrenia.

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.

Association of rs4680 COMT, rs6280 DRD3, and rs7322347 5HT2A With Clinical Features of Youth-Onset Schizophrenia

We investigated the associations of rs4680 COMT, rs6280 DRD3, and rs7322347 5HT2A with youth-onset schizophrenia in the Russian population in a case-control study, and the role of the genotype in the severity of clinical features. The association between rs7322347 and schizophrenia (p = 0.0001) is described for the first time. Furthermore, we found a link with rs6280 and rs4680 in females (p = 0.001 and p = 0.02 respectively) and with rs7322347 in males (p = 0.002). Clinical symptoms were assessed on three scales: the Clinician-Rated Dimensions of Psychosis Symptom Severity scale, Positive and Negative Syndrome Scale, and Frontal Assessment Battery. Gender differences in clinical features are of particular interest. In our study we found gender differences in the severity of clinical features-higher scores for delusions (Positive and Negative Syndrome Scale and Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition) in males and higher scores for depression, delusions, somatic concern, motor retardation, poor attention were found in females.