A new generation of antipsychotics: pharmacology and clinical utility of cariprazine in schizophrenia

Effect of ponatinib on the metabolism of cariprazine in vitro and in vivo and the underlying mechanism

Cariprazine is an antipsychotic medication that has been approved for the treatment of schizophrenia and manic or mixed episodes. Patients with tumors frequently develop psychiatric disorders, necessitating the combination of antitumor and antipsychotic drugs. The objective of the present study was to examine the inhibitory impacts of three antitumor drugs (olmutinib, napabucasin and ponatinib) on the metabolism of cariprazine, and the molecular docking of cariprazine and ponatinib in relation to CYP3A4 was also evaluated. As the results, the half-maximal inhibitory concentration (IC50) values of ponatinib and olmutinib in vitro were < 10 μM, whereas napabucasin was >20 μM. Among these, ponatinib exhibited the smallest IC50 value. The metabolic stability of cariprazine was observed in the presence or absence of ponatinib in rat liver microsomes (RLM). The IC50 shift experiments demonstrated that the inhibition of cariprazine by ponatinib was non-time-dependent. In addition, ponatinib was shown to inhibit cariprazine in a mixed manner (RLM) and a competitive manner (HLM), respectively. In the in vivo study, the co-administration of ponatinib resulted in a significant 0.35-fold increase in both AUC(0-t) and AUC(0-∞) for cariprazine, accompanied by a significant 0.25-fold decrease in the CLz/F. Furthermore, the metabolites desmethyl-cariprazine (DCAR) and didesmethyl-cariprazine (DDCAR) exhibited disparate increases in both AUC(0-t) and AUC(0-∞). Molecular docking studies had demonstrated that both cariprazine and ponatinib could engage in hydrophobic interactions with residue PHE-304 on CYP3A4. Consequently, when ponatinib is employed in conjunction with cariprazine in a clinical setting, it is imperative to assess the efficacy and adverse effects, and adjust the dosage to attain the optimal efficacy.

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.

Enhanced computerized cognitive remediation therapy improved cognitive function, negative symptoms, and GDNF in male long-term inpatients with schizophrenia

Objective

Negative and cognitive symptoms present significant challenges in patients with schizophrenia, and cognitive remediation is a promising approach to alleviate these symptoms. This study aimed to explore the efficacy of computerized cognitive remediation therapy (CCRT) on psychiatric symptoms, cognitive deficits, and serum levels of brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) in patients with schizophrenia.

Materials and methods

Forty male long-term institutionalized inpatients with schizophrenia were assigned to either a CCRT group (n = 20) or a control group (n = 20). The CCRT intervention consisted of 40 individual 40-min sessions over 8 weeks, conducted five times a week. Psychiatric symptoms, cognition, and serum levels of BDNF and GDNF were assessed at baseline, 4 weeks, and 8 weeks.

Results

Compared to the control group, the CCRT group exhibited decreased total Positive and Negative Syndrome Scale and negative subscale scores, as well as increased Montreal Cognitive Assessment and Repeatable Battery for the Assessment of Neuropsychological Status scores. Moreover, improvements in list recall were associated with reduced negative symptoms. Additionally, CCRT ameliorated the decrease in serum GDNF levels in patients with schizophrenia.

Conclusion

The effectiveness of CCRT in alleviating negative symptoms was associated with improvements in list recall, and GDNF may play a role in the observed effects of CCRT in patients with schizophrenia.

Optimisation of pharmacotherapy in psychiatry through therapeutic drug monitoring, molecular brain imaging and pharmacogenetic tests: Focus on antipsychotics

BACKGROUND

For psychotic disorders (i.e. schizophrenia), pharmacotherapy plays a key role in controlling acute and long-term symptoms. To find the optimal individual dose and dosage strategy, specialised tools are used. Three tools have been proven useful to personalise drug treatments: therapeutic drug monitoring (TDM) of drug levels, pharmacogenetic testing (PG), and molecular neuroimaging.

METHODS

In these Guidelines, we provide an in-depth review of pharmacokinetics, pharmacodynamics, and pharmacogenetics for 45 antipsychotics. Over 30 international experts in psychiatry selected studies that have measured drug concentrations in the blood (TDM), gene polymorphisms of enzymes involved in drug metabolism, or receptor/transporter occupancies in the brain (positron emission tomography (PET)).

RESULTS

Study results strongly support the use of TDM and the cytochrome P450 (CYP) genotyping and/or phenotyping to guide drug therapies. Evidence-based target ranges are available for titrating drug doses that are often supported by PET findings.

CONCLUSION

All three tools discussed in these Guidelines are essential for drug treatment. TDM goes well beyond typical indications such as unclear compliance and polypharmacy. Despite its enormous potential to optimise treatment effects, minimise side effects and ultimately reduce the global burden of diseases, personalised drug treatment has not yet become the standard of care in psychiatry.

Volumetric absorptive microsampling for the therapeutic drug monitoring of psychiatric patients treated with cariprazine

Psychiatric disorders are usually treated with antipsychotic agents belonging to different pharmacological and chemical classes, the most recent ones collectively known as "third-generation antipsychotics", such as cariprazine, approved in 2015 for the treatment of patients affected by schizophrenia. For these patients, a frequent therapeutic drug monitoring (TDM) becomes essential to assess compliance and to optimise and personalise their therapy, also due to cariprazine interindividual variability and narrow therapeutic range. In this study, a bioanalytical method featuring miniaturised sampling and pretreatment was developed, based on volumetric absorptive microsampling (VAMS) for TDM of psychiatric patients under cariprazine treatment and compared to a reference method based on fluid plasma analysis. Minimally invasive whole blood VAMS was coupled to an original instrumental method based on ultra-high performance liquid chromatography hyphenated to mass spectrometry (UHPLC-MS). A feasible and streamlined, yet reliable VAMS pretreatment protocol was carefully optimised and the VAMS-UHPLC-MS methodology was validated with satisfactory results in terms of linearity (r2 > 0.9970 in the 1.5-100 ng/mL range), precision (%RSD < 11.7), extraction yield (> 90.0 %) and matrix effect (8.2 ≤ %RE ≤ 10.9). Finally, the microsampling approach coupled to UHPLC-MS was successfully applied to the TDM of psychiatric patients treated with cariprazine and compared with standard fluid plasma analysis, providing reliable quali-quantitative results, and proving to be readily applicable to the clinical practice in TDM programs as a useful alternative to cariprazine plasma analysis. This is the first report of a successful microsampling application, and in particular the first report of VAMS application, for the TDM of cariprazine.

Cariprazine for Treating Schizophrenia, Mania, Bipolar Depression, and Unipolar Depression: A Review of Its Efficacy

This drug review presents a comprehensive review of Cariprazine, a medication that received FDA approval in 2015 for treating schizophrenia and bipolar disorder. The paper begins by exploring Cariprazine's mechanism of action, which involves modulating dopamine and serotonin receptors. Additionally, the review assesses Cariprazine's metabolic profile and notes its low potential for weight gain and metabolic side effects. The study examines Cariprazine's efficacy and safety in treating various psychiatric disorders, such as schizophrenia, bipolar maintenance, mania, and bipolar depression. A meticulous analysis of clinical trials is included, demonstrating Cariprazine's potential advantages over existing medications used for these disorders. Additionally, the review covers Cariprazine's recent approval as an adjuvant treatment for unipolar depression. Furthermore, the paper examines the limitations of Cariprazine, such as the absence of head-to-head trials comparing it to other commonly used medications for these disorders. The paper concludes by emphasizing the need for more research to establish Cariprazine's position in treating schizophrenia and bipolar disorder and determine its comparative effectiveness with other available treatments.

Evaluation of the Effect of Cariprazine on Memory and Cognition in Experimental Rodent Models

The main symptoms of schizophrenia are categorized as positive, negative, and cognitive. Cognitive impairments do not generally respond to antipsychotics. Cariprazine is a novel antipsychotic conceived with the idea that high affinity for D3 receptors may elicit a favorable response in the management of cognitive deficits. We evaluated the pro-cognitive properties of 14-day long pre-treatment with cariprazine (0.25, 0.5, and 1 mg/kg b.w. intraperitoneally) in experimental rodent models with scopolamine-induced memory impairment employing novel object recognition test (NORT), T-maze, Y-maze, and passive avoidance tasks (step-through and step-down). Statistical analysis was performed with One Way ANOVA. In NORT cariprazine increased the recognition index. In T-maze and Y-maze cariprazine increased the working memory index as well as the percentage of spontaneous alternation. Cariprazine improved learning and memory in both short-term and long-term memory retention tests in step-down and step-through tasks. Cariprazine improves learning, recognition, and spatial memory in rats with scopolamine-induced memory impairment. Cariprazine's beneficial effect on cognition is likely due to its affinity for D3 receptors, as well as agonism at 5-HT1A receptors. Most probably, the cognitive-enhancing properties of cariprazine are the result of integrated modulation in the amygdala, hippocampus, and prefrontal cortex.

Add-on Cariprazine in Patients with Long-term Clozapine Treatment and Treatment Resistant Schizophrenia: Two Cases of Psychotic Deterioration and Pisa Syndrome

An increasing number of studies deal with medical options for treatment resistant schizophrenia. If no remission can be achieved with clozapine, a combination of antipsychotics can be considered. The combination of clozapine and cariprazine is rarely studied. Cariprazine is a partial agonist on dopamine D₂ and D₃ receptors and a pharmaceutically rational add-on to clozapine. Stimulating D₃ receptors has been linked to improved cognition and mood, with negligible extrapyramidal side effects. We present two patients with long-term treatment resistant schizophrenia receiving cariprazine and clozapine. Whereas psychotic symptoms worsened, the patients developed extrapyramidal side effects with a Pisa syndrome. The syndrome remitted after discontinuation of cariprazine. Possible explanations by pharmacodynamic interactions and drug specific receptor profiles are discussed.

Clozapine augmentation with cariprazine for negative symptoms: a case series and literature review

Only about 50% of patients with treatment-resistant schizophrenia respond to clozapine, and many more patients continue to experience ongoing and prominent negative symptoms. These negative symptoms, for which there are limited pharmacological options, may represent the greatest barrier to functional recovery. Cariprazine is a novel antipsychotic drug that is a partial agonist at dopamine D₂ and D₃ receptors with preferential binding to the D₃ receptor, antagonism of 5HT_2B receptors, and partial agonism at 5HT_1A receptors. Cariprazine is currently licenced for the treatment of schizophrenia in Europe and the United States and has also been approved for bipolar disorder in the United States. There is a limited body of evidence to suggest clinical effectiveness as an augmentation strategy for negative symptoms in those treated with clozapine. In this case series, we present five cases of successful treatment of negative symptoms by clozapine combined with cariprazine in treatment-resistant psychosis.

Treatment of Symptom Clusters in Schizophrenia, Bipolar Disorder and Major Depressive Disorder With the Dopamine D3/D2 Preferring Partial Agonist Cariprazine

Cariprazine is currently approved for the treatment of patients with schizophrenia (USA and EU), and for manic, depressive, and episodes with mixed features in bipolar I disorder (USA): several randomized controlled studies have also explored its efficacy in patients with major depressive disorder. This review summarizes its current therapeutic uses and potential advantages for treating the main symptoms of schizophrenia, bipolar I and major depressive disorder, considering its pharmacodynamic properties, efficacy, and tolerability. Its predominantly D3 receptor preferring affinity, with functional selectivity according to the prevailing neuronal environment, contributes to its efficacy across a wide array of psychopathological symptoms (including reality distortion, disorganized thought, negative symptoms, mood disturbance, anhedonia, and cognitive impairment), and to a favorable side effect profile. Cariprazine may be a "drug of choice" in patients with predominant negative and cognitive symptoms of schizophrenia, as well as those with metabolic syndrome. Further investigation of its relative efficacy when compared to aripiprazole or other active comparators is warranted. Its effectiveness in the treatment of bipolar mania, bipolar I depression and bipolar I episodes with mixed features, with minimal accompanying metabolic changes is well-established. The longer half-life and delayed time to relapse in patients diagnosed with schizophrenia when compared to other second-generation antipsychotics represent other advantages, given the high rates of non-adherence and frequent relapses seen in clinical practice. Its efficacy in overlapping symptom domains in other major psychiatric disorders appears promising.

TPN672: A Novel Serotonin-Dopamine Receptor Modulator for the Treatment of Schizophrenia

TPN672 [7-(2-(4-(benzothiophen-4-yl) piperazin-1-yl)ethyl)quinolin-2(1H)-one maleate] is a novel antipsychotic candidate with high affinity for serotonin and dopamine receptors that is currently in clinical trial for the treatment of psychiatric disorders. In vitro binding study showed that TPN672 exhibited extremely high affinity for serotonin 1A receptor (5-HT1AR) (K i = 0.23 nM) and 5-HT2AR (K i = 2.58 nM) as well as moderate affinity for D3R (K i = 11.55 nM) and D2R (K i = 17.91 nM). In vitro functional assays demonstrated that TPN672 acted as a potent 5-HT1AR agonist, D2R/D3R partial agonist, and 5-HT2AR antagonist. TPN672 displayed robust antipsychotic efficacy in rodent models (e.g., blocking phencyclidine-induced hyperactivity), significantly better than aripiprazole, and ameliorated negative symptoms and cognitive deficits in the sociability test, dark avoidance response, Morris water maze test, and novel object recognition test. The results of electrophysiological experiments showed that TPN672 might inhibit the excitability of the glutamate system through activating 5-HT1AR in medial prefrontal cortex, thereby improving cognitive and negative symptoms. Moreover, the safety margin (the ratio of minimum catalepsy-inducing dose to minimum effective dose) of TPN672 was about 10-fold, which was superior to aripiprazole. In conclusion, TPN672 is a promising new drug candidate for the treatment of schizophrenia and has been shown to be more effective in attenuating negative symptoms and cognitive deficits while having lower risk of extrapyramidal symptoms and hyperprolactinemia. SIGNIFICANCE STATEMENT: TPN672 is a promising new drug candidate for the treatment of schizophrenia and has been shown to be more effective in attenuating negative symptoms and cognitive deficits while having a lower risk of extrapyramidal symptoms and hyperprolactinemia. A phase I clinical trial is now under way to test its tolerance, pharmacokinetics, and pharmacodynamic effects in human volunteers. Accordingly, the present results will have significant impact on the development of new antischizophrenia drugs.

Synthesis and biological evaluation of a new class of multi-target heterocycle piperazine derivatives as potential antipsychotics

In this study, we designed and synthesized a novel series of multi-receptor ligands as polypharmacological antipsychotic agents by using a multi-receptor affinity strategy. Among them, 3w combines a multi-receptor mechanism with high mixed affinities for D₂, 5-HT_1A, 5-HT_2A and H₃ receptors, and low efficacy at the off-target receptors (5-HT_2C, H₁ and α₁ receptor) and human ether-à-go-go-related gene (hERG) channel. In addition, compound 3w exhibits favorable antipsychotic drug-like activities in in vivo assessment. An animal behavioral study revealed that compound 3w significantly reverses apomorphine-induced climbing and MK-801-induced hyperactivity, and avoidance behavior in the CAR test, with a high threshold for catalepsy. Moreover, compound 3w demonstrates memory enhancement in a novel object recognition task and low liabilities for weight gain and hyperprolactinemia in a long-term metabolic adverse effects model. Thus, 3w was selected as an antipsychotic candidate for further development.

In this study, we designed and synthesized a novel series of multi-receptor ligands as polypharmacological antipsychotic agents by using a multi-receptor affinity strategy.

Altered Cholesterol Biosynthesis Affects Drug Metabolism

The last step of cholesterol biosynthesis is the conversion of 7-dehydrocholesterol (7-DHC) into cholesterol, a reaction catalyzed by dehydrocholesterol reductase 7 (DHCR7). Investigation of the effect of Dhcr7 single-allele mutations on the metabolism of aripiprazole (ARI) and cariprazine (CAR) in maternally exposed transgenic pups revealed that ARI, CAR, and their active metabolites were decreased in the liver and brain of Dhcr7 ^+/- . This difference in the drug and metabolite levels resulted in an increased turnover of ARI and CAR in tissues from Dhcr7 ^+/- animals, indicating an enhanced metabolism, which was at least partially due to increased levels of Cyp2d6 in the liver of Dhcr7 ^+/- mice. Finally, experiments with both WT and DHCR7 ^+/- human fibroblasts revealed lower drug levels in DHCR7 ^+/- heterozygous cells. Our findings have potential clinical implications, as DHCR7 heterozygosity is present in 1-3% in the human population, and these individuals might have reduced therapeutic levels of Cyp2d6-metabolized medications and are putatively more susceptible to unwanted side effects.

Cariprazine in the Treatment of Bipolar Disorder: Within and Beyond Clinical Trials

Bipolar disorder (BD) is chronic psychiatric disorder associated with significant impairment in psychosocial functioning and quality of life. Although current pharmacological treatments for BD have improved its clinical management, many patients do not achieve remission, particularly those suffering from bipolar depression. In addition, available treatments are associated with a myriad of potential adverse effects, which highlights the need for novel therapeutic agents that can be effective for both phases of the illness with a reduced side effect burden. Cariprazine is a novel antipsychotic that is a dopamine D2/D3 partial agonist with a preference for D3 receptors. In this review, we examine the pharmacological properties, clinical efficacy and tolerability profile of cariprazine in patients with BD, taking into account the latest clinical trials data. We also review post hoc analyses addressing clinically relevant subgroups and symptom domains in BD. Current evidence suggests efficacy for cariprazine 3-12 mg/day in the treatment of acute manic and mixed episodes; for bipolar depression, the efficacy of cariprazine appears to be dose-related, with doses of 1.5-3 mg/day beneficial as monotherapy. Cariprazine is overall well-tolerated by patients in both manic and depressive episodes. Its most common side effects relative to placebo include akathisia, extrapyramidal symptoms and nausea. There are no metabolic concerns reported with cariprazine use. In summary, the latest evidence suggests that cariprazine is an effective and safe treatment option for BD.

Negative Symptoms of Schizophrenia: New Prospects of Cariprazine Treatment

Background

Cariprazine is a new piperazine derivative atypical antipsychotic, like aripiprazole and brexpiprazole. It has been approved for treating schizophrenia in many countries and has recently been included on the List of Essential Medicines in Russia. Unlike most other atypical antipsychotics, it shows high in vivo occupancy of dopamine D2 and D3 receptors at clinically relevant doses. In animal models, cariprazine has demonstrated dopamine D3 receptor-dependent pro-cognitive and anti-anhedonic effects, suggesting its potential for treating negative symptoms. This review summarizes the efficacy of cariprazine in the treatment of negative symptoms of schizophrenia.

Methods

A literature search of databases covering international and Russian journals, for articles published between 1st January 2010 and 1st June 2020.

Results

Cariprazine demonstrated at least comparable efficacy in the treatment of schizophrenia symptoms to active comparators including risperidone, olanzapine or aripiprazole. The drug has a good safety profile. It appeared to be associated with a lower risk of metabolic syndromes and most extrapyramidal symptoms. The positive effect of cariprazine on the negative symptoms of schizophrenia may be associated with the elimination of secondary negative symptoms. However, of all the atypical antipsychotics to date, only cariprazine has a convincingly, methodologically robust proven advantage over risperidone in eliminating the predominant negative symptoms of schizophrenia. Yet only four studies have investigated the effect of cariprazine on the negative symptoms of schizophrenia. There is a lack of research into its direct impact on emotional-volitional disorders, anhedonia, cognitive symptoms and personality changes. However, there is evidence to suggest cariprazine is effective in treatment-resistant cases, but this requires further confirmation.

Conclusion

Cariprazine is an effective and well-tolerated agent for the treatment of schizophrenia and may be effective in cases where other antipsychotics have failed. Cariprazine has been shown to have a positive effect on negative symptoms. Further studies are needed to collect more data on long-term treatment of schizophrenia and especially negative symptoms.

Urea Derivatives in Modern Drug Discovery and Medicinal Chemistry

The urea functionality is inherent to numerous bioactive compounds, including a variety of clinically approved therapies. Urea containing compounds are increasingly used in medicinal chemistry and drug design in order to establish key drug-target interactions and fine-tune crucial drug-like properties. In this perspective, we highlight physicochemical and conformational properties of urea derivatives. We provide outlines of traditional reagents and chemical procedures for the preparation of ureas. Also, we discuss newly developed methodologies mainly aimed at overcoming safety issues associated with traditional synthesis. Finally, we provide a broad overview of urea-based medicinally relevant compounds, ranging from approved drugs to recent medicinal chemistry developments.

Medication-Induced Akathisia with Newly Approved Antipsychotics in Patients with a Severe Mental Illness: A Systematic Review and Meta-Analysis

BACKGROUND

Akathisia is a common and distressing movement disorder that can be associated with the use of antipsychotics. It is characterized by a subjective (inner restlessness) and an objective (excessive movements) component. Akathisia can have a negative impact on clinical outcome and even lead to treatment discontinuation. Although medication-induced akathisia is more commonly associated with the use of first-generation antipsychotics (FGAs), it also occurs with second-generation antipsychotics (SGAs), including the newly approved antipsychotics (NAPs) asenapine, lurasidone, iloperidone, cariprazine, and brexpiprazole. Until now, no meta-analysis has been published on the risk of akathisia for all NAPs, as monotherapy or adjunctive treatment, in patients with a severe mental illness.

OBJECTIVE

The primary objectives of this systematic review and meta-analysis were to (i) compare akathisia incidence rates of the NAPs, as monotherapy or adjunctive treatment, in adult patients with a severe mental illness (i.e., schizophrenia, bipolar disorder, or major depressive disorder), using data from published and unpublished randomized controlled trials; and (ii) examine the role of several study characteristics explaining differences in akathisia incidence rates between studies.

METHODS

A systematic literature search, using the PubMed, EMBASE, and Cochrane Library databases (until October 2018), was conducted for English-language placebo- as well as active-controlled clinical trials, including subjective (percentage of patients reporting akathisia) and/or scale-defined medication-induced akathisia incidence rates with NAPs (as monotherapy or as adjunctive treatment) in adult patients with schizophrenia, bipolar disorder, or major depressive disorder. Additional unpublished clinical trials were identified through the ClinicalTrials.gov electronic database. Two meta-analyses (incidence rates and odds ratio [OR] [placebo vs. active] of medication-induced akathisia with NAPs) were performed to obtain an optimal estimation of akathisia risks of adult patients with a severe mental illness under these treatment conditions and to assess the role of study characteristics.

RESULTS

Two hundred and thirteen reports were selected as potentially eligible for our meta-analysis. Of these, 48 met the inclusion criteria. Eight records, identified through the ClinicalTrials.gov database and cross-referencing, and which fulfilled the inclusion criteria, were added, resulting in a total of 56 records (iloperidone = 5, asenapine = 11, lurasidone = 15, brexpiprazole = 13, cariprazine = 12). The estimated weighted mean incidence rate of akathisia was 7.7% (95% confidence interval [CI] 6.5-9.1), with estimates being 3.9% (95% CI 2.4-6.3) for iloperidone, 6.8% (95% CI 5.1-9.0) for asenapine, 10.0% (95% CI 7.4-13.5) for brexpiprazole, 12.7% (95% CI 10.1-16.1) for lurasidone, and 17.2% (95% CI 13.4-22.1) for cariprazine. After Tukey-adjustment for multiple testing, the incidence rate of akathisia was significantly (p < 0.05) lower for iloperidone than for brexpiprazole, lurasidone, and cariprazine. In addition, the incidence rate of akathisia was significantly (p < 0.05) lower for asenapine than for lurasidone and cariprazine. Finally, the incidence rate of akathisia was significantly (p < 0.05) lower for brexpiprazole than for cariprazine. Type of medication (p < 0.0001), diagnosis (p = 0.02), and race (p = 0.0003) significantly explained part of the heterogeneity of the incidence estimates of akathisia between studies. The estimated weighted OR of akathisia under medication, compared with placebo, was 2.43 (95% CI 1.91-3.10). The OR was smallest for iloperidone (OR 1.20; 95% CI 0.42-3.45) and increased for brexpiprazole (OR 2.04; 95% CI 1.09-3.83), asenapine (OR 2.37; 95% CI 1.32-4.27), lurasidone (OR 3.74; 95% CI 2.32-6.02), and cariprazine (OR 4.35; 95% CI 2.80-6.75). Only type of medication (p = 0.03) explained systematic differences in the OR for akathisia between placebo versus active treatment across studies. After Tukey-adjustment for multiple testing, no significant differences between these ORs were found. The severity of akathisia with NAPs generally is mild to moderate, only leading to treatment discontinuation in a minority of cases (< 5%).

CONCLUSIONS

The use of a NAP raises the akathisia risk more than two-fold when compared with patients receiving placebo. Although distinctions between the different NAPs were not clear in placebo-controlled trials, the results of our meta-analyses and systematic review generally indicate that these differences more than likely reflect real differences, with iloperidone showing the most and cariprazine showing the least benign akathisia profile. Moreover, due to patient characteristics and methodological issues, incidence rates of akathisia with NAPs found in this meta-analysis may even be an underestimation of true incidence rates.

Antidepressant activities of escitalopram and blonanserin on prenatal and adolescent combined stress-induced depression model: Possible role of neurotrophic mechanism change in serum and nucleus accumbens

BACKGROUND

There has been number of studies suggesting experiences of adversity in early life interrelated subsequent brain development, however, neurobiological mechanisms confer risk for onset of psychiatric illness remains unclear.

METHODS

In order to elucidate the pathogenic mechanisms underlying early life adversity-induced refractory depression in more detail, we administered corticosterone (CORT) to adolescent rats with or without prenatal ethanol exposure followed by an antidepressant or antipsychotic and examined alterations in depressive and social function behaviors and brain-derived neurotrophic factor (BDNF) levels in serum, the hippocampus, anterior cingulate cortex, and nucleus accumbens.

RESULTS

The combined stress exposure of prenatal ethanol and adolescent CORT prolonged immobility times in the forced swim test (FST), and increased investigation times and numbers in the social interaction test (SIT). A treatment with escitalopram reversed depression-like behavior accompanied by reductions in BDNF levels in serum and the nucleus accumbens, while a treatment with blonanserin ameliorated abnormal social interaction behavior with reductions in serum BDNF levels.

LIMITATIONS

Further studies are needed to clarify the clinical evinces responding to these results, and many questions remain regarding the mechanisms by which refractory depression and antidepressant/antipsychotic treatments cause changes in serum and brain regional BDNF levels.

CONCLUSION

These results strongly implicate changes in BDNF levels in serum and the nucleus accumbens in the pathophysiology and treatment of early life combined stress-induced depression and highlight the therapeutic potential of escitalopram and new generation antipsychotic blonanserin for treatment-resistant refractory depression.

Early antipsychotic exposure affects NMDA and GABAA receptor binding in the brains of juvenile rats

Antipsychotics were developed to treat schizophrenia in adults; however they have been increasingly prescribed in children and adolescents. The NMDA and GABA_A receptors are involved in neurodevelopment and the pathophysiology of various mental disorders in children and adolescents. Male and female juvenile rats were treated orally with risperidone (0.3 mg/kg, 3 times/day), aripiprazole (1 mg/kg), olanzapine (1 mg/kg) or vehicle (control), starting from postnatal day (PD) 23 (±1 day) for 3 weeks (corresponding to the childhood-adolescent period in humans). Quantitative autoradiography was used to detect the binding density of [³H]MK-801 (an NMDA receptor antagonist) and [³H]muscimol (a selective GABA_A receptor agonist). Aripiprazole elevated the [³H]MK801 binding levels in the NAcC of male rats, and the NAcS and CPu of female rats. Risperidone increased [³H]MK801 levels in the CPu of female rats, and the NAcS of male rats. Aripiprazole upregulated [³H]muscimol binding levels in the CPu and NAcC of male rats, while it elevated the [³H]muscimol levels in the PFC of female rats, compared to controls. These results suggest that early treatment with these antipsychotics modulates NMDA and GABA_A neurotransmission in juveniles, which may play a role in their clinical efficacy in the control of mental disorders in children and adolescents.

The preclinical discovery and development of cariprazine for the treatment of schizophrenia

INTRODUCTION

Cariprazine is approved in the United States and Europe for the treatment of manic or mixed episodes associated with bipolar I disorder and for the treatment of schizophrenia in adult patients. It is typically administered orally once a day (a dose range 1.5 - 6 mg/day), does require titration, and may be given with or without food. It has a half-life of 2 - 4 days with an active metabolite that has a terminal half-life of 2 - 3 weeks. Areas covered: This review article focuses on the preclinical discovery of cariprazine providing details regarding its pharmacological, behavioral, and neurochemical mechanisms and its contribution to clinical therapeutic benefits. This article is based on the available literature with respect to the preclinical and clinical findings and product labels of cariprazine. Expert opinion: Cariprazine shows highest affinity toward D₃ receptors, followed by D₂, 5-HT_2B, and 5-HT_1A receptors. It also shows moderate affinity toward σ₁, 5-HT_2A, and histamine H₁ receptors. Long-term administration of cariprazine altered the abundance of dopamine, serotonin, and glutamate receptor subtypes in different brain regions. All these mechanisms of cariprazine may contribute toward its unique preclinical profile and its clinically observed benefits in the treatment of schizophrenia, bipolar mania, and possibly other psychiatric disorders.

Antipsychotic-induced Tardive dyskinesia: from biological basis to clinical management

INTRODUCTION

Tardive dyskinesia (TD) is a chronic and disabling movement disorder with a complex pathophysiological basis. A significant percentage of patients does not receive correct diagnosis, resulting in delayed or inaccurate treatment and poor outcome. Therefore, there is a critical need for prompt recognition, implementation of efficacious treatment regimens and long-term follow up of patients with TD. Areas covered: The current paper provides an overview of emerging data concerning proposed pathophysiology theories, epidemiology, risk factors, and therapeutic strategies for TD. Expert commentary: Despite considerable research efforts, TD remains a challenge in the treatment of psychosis as the available strategies remain sub-optimal. The best scenario will always be the prophylaxis or prevention of TD, which entails limiting the use of antipsychotics.

Managing interactions between cognitive enhancers and other psychotropics

Polypharmacy is common in psychiatry. Usage of cognitive enhancers is increasing in the psychiatric population. Many clinicians are not familiar with these new psychoactive compounds. This paper reviews the potential drug-drug interactions when these cognitive enhancers are used together with psychotropic drugs and their confounding effects on diagnosis and clinical management.

Cariprazine for the Treatment of Bipolar Disorder

PURPOSE

To review the data regarding a new antipsychotic, cariprazine.

CONCLUSIONS

Cariprazine is a dopamine D3, D2 partial agonist, with greater affinity to D3. It has been examined for schizophrenia, bipolar mania, bipolar depression, and unipolar depression. It has demonstrated efficacy in schizophrenia and mania, and has recently been approved by the U.S. Food and Drug Administration. However, it has a more inconsistent effect in depression, both unipolar and bipolar. Adverse effects include extrapyramidal symptoms, akathisia, and gastrointestinal distress.

PRACTICE IMPLICATIONS

Cariprazine will be a promising addition in the treatment of patients with acute mania and schizophrenia.

RP5063, an atypical antipsychotic drug with a unique pharmacologic profile, improves declarative memory and psychosis in mouse models of schizophrenia

Various types of atypical antipsychotic drugs (AAPDs) modestly improve the cognitive impairment associated with schizophrenia (CIAS). RP5063 is an AAPD with a diverse and unique pharmacology, including partial agonism at dopamine (DA) D₂, D₃, D₄, serotonin (5-HT)_1A, and 5-HT_2A receptors (Rs), full agonism at α₄β₂ nicotinic acetylcholine (ACh)R (nAChR), and antagonism at 5-HT_2B, 5-HT₆, and 5-HT₇Rs. Most atypical APDs are 5-HT_2A inverse agonists. The efficacy of RP5063 in mouse models of psychosis and episodic memory were studied. RP5063 blocked acute phencyclidine (PCP)-as well as amphetamine-induced hyperactivity, indicating antipsychotic activity. Acute administration of RP5063 significantly reversed subchronic (sc)PCP-induced impairment in novel object recognition (NOR), a measure of episodic memory, but not reversal learning, a measure of executive function. Co-administration of a sub-effective dose (SED) of RP5063 with SEDs of a 5-HT₇R antagonist, a 5-HT_1BR antagonist, a 5-HT_2AR inverse agonist, or an α₄β₂ nAChR agonist, restored the ability of RP5063 to ameliorate the NOR deficit in scPCP mice. Pre-treatment with a 5-HT_1AR, a D₄R, antagonist, but not an α₄β₂ nAChR antagonist, blocked the ameliorating effect of RP5063. Further, co-administration of scRP5063 prior to each dose of PCP prevented the effect of PCP to produce a deficit in NOR for one week. RP5063, given to scPCP-treated mice for one week restored NOR for one week only. Acute administration of RP5063 significantly increased cortical DA efflux, which may be critical to some of its cognitive enhancing properties. These results indicate that RP5063, by itself, or as an adjunctive treatment has a multifaceted basis for improving some cognitive deficits associated with schizophrenia.

The dopamine D₃-preferring D₂/D₃ dopamine receptor partial agonist, cariprazine, reverses behavioural changes in a rat neurodevelopmental model for schizophrenia

Current antipsychotic medication is largely ineffective against the negative and cognitive symptoms of schizophrenia. One promising therapeutic development is to design new molecules that balance actions on dopamine D2 and D3 receptors to maximise benefits and limit adverse effects. This study used two rodent paradigms to investigate the action of the dopamine D3-preferring D3/D2 receptor partial agonist cariprazine. In adult male rats, cariprazine (0.03-0.3 mg/kg i.p.), and the atypical antipsychotic aripiprazole (1-3 mg/kg i.p.) caused dose-dependent reversal of a delay-induced impairment in novel object recognition (NOR). Treating neonatal rat pups with phencyclidine (PCP) and subsequent social isolation produced a syndrome of behavioural alterations in adulthood including hyperactivity in a novel arena, deficits in NOR and fear motivated learning and memory, and a reduction and change in pattern of social interaction accompanied by increased ultrasonic vocalisations (USVs). Acute administration of cariprazine (0.1 and 0.3 mg/kg) and aripiprazole (3 mg/kg) to resultant adult rats reduced neonatal PCP-social isolation induced locomotor hyperactivity and reversed NOR deficits. Cariprazine (0.3 mg/kg) caused a limited reversal of the social interaction deficit but neither drug affected the change in USVs or the deficit in fear motivated learning and memory. Results suggest that in the behavioural tests investigated cariprazine is at least as effective as aripiprazole and in some paradigms it showed additional beneficial features further supporting the advantage of combined dopamine D3/D2 receptor targeting. These findings support recent clinical studies demonstrating the efficacy of cariprazine in treatment of negative symptoms and functional impairment in schizophrenia patients.

New developments in the management of schizophrenia and bipolar disorder: potential use of cariprazine

Cariprazine is a recently developed antipsychotic drug with a partial agonism for the D₂ and D₃ receptors. It shows a tenfold greater affinity for the D₃ receptor. In clinical trials, its therapeutic effect has been tested in patients with an acute exacerbation of schizophrenia and in patients with acute mania in bipolar disorder. Like risperidone, cariprazine improves positive and negative schizophrenic symptoms, and ameliorates cognitive functions. Cariprazine induces extrapyramidal symptoms less often than risperidone and can cause acute akathisia. It is a prolactin-sparing antipsychotic drug and has a favorable metabolic profile. In acute mania in bipolar disorder, it treats manic symptoms significantly better than placebo. As a consequence of its improved adverse effects, cariprazine improves patients’ quality of life to a greater extent than other second-generation antipsychotic drugs. Cariprazine is a promising antipsychotic drug in the treatment of schizophrenia, acute mania in bipolar disorder, and in schizophrenia with mania. In these patients, its long-term therapeutic effect and its action in comparison with other second-generation antipsychotic drugs, above all aripiprazole, remain to be tested in clinical trials.

Pharmacological targeting of dopamine D3 receptors: Possible clinical applications of selective drugs

Dopamine D3 receptors have been pharmacologically engaged in humans since the development of the first antipsychotics and ergot-derivative dopamine (DA) agonists, even without knowing it. These agents were generally non-selective, developed primarily to target D2 receptors. In the last 10 years the understanding of the clinical implication of D3 receptors has been progressing also due to the identification of D3 gene polymorphisms, the use of more selective PET ligands such as [(11)C]-(+)-PHNO and the learning regarding the clinical use of the D3-preferential D2/D3 agonists ropinirole and pramipexole. A new specific neuroplasticity role of D3 receptor regarding dendrite arborisation outgrowth in dopaminergic neurons was also proposed to support, at least in part, the slowing of disease observed in subjects with Parkinson׳s Disease treated with DA agonists. Similar mechanisms could be at the basis of the antidepressant-like effects observed with DA agonists when co-administered with standard of care. Severe adverse event occurring with the use of anti-parkinsonian DA agonists in predisposed subjects, i.e., impulse control disorders, are now suggested to be putatively related to overactive D3 receptors. Not surprisingly, blockade of D3 receptors was proposed as treatment for addictive disorders, a goal that could be potentially achieved by repositioning buspirone, an anxiolytic drug with D3-preferential antagonistic features, or with novel selective D3 antagonists or partial agonists currently in development for schizophrenia. At the moment ABT-925 is the only selective D3 antagonist tested in schizophrenic patients in Phase II, showing an intriguing cognitive enhancing effects supported by preclinical data. Finally, exploratory pharmacogenetic analysis suggested that ABT-925 could be effective in a subpopulation of patients with a polymorphism on the D3 receptor, opening to a possible personalised medicine approach.

Clinical pharmacology of atypical antipsychotics: an update

This review will concentrate on the clinical pharmacology, in particular pharmacodynamic data, related to atypical antipsychotics, clozapine, risperidone, paliperidone, olanzapine, que¬tiapine, amisulpride, ziprasidone, aripiprazole, asenapine, iloperidone, lurasidone and cariprazine. A summary of their acute pharmacokinetics properties are also reported. Four new second-generation antipsychotics are available: iloperidone, asenapine, lurasidone and in the next future cariprazine. Similar to ziprasidone and aripiprazole, these new agents are advisable for the lower propensity to give weight gain and metabolic abnormalities in comparison with older second-generation antipsychotics such as olanzapine or clozapine. Actually lurasidone seems to be best in terms of minimizing unwanted alterations in body weight and metabolic variables. Therapeutic drug monitoring is not strictly necessary for all of the new antipsychotic drugs because there are no unequivocal data supporting a relationship between plasma drug levels and clinical outcomes or side effects. The exception can be represented by clozapine for which plasma levels of 350-420 ng/ml are reported to be associated with an increased probability of a good clinical response. Also for olanzapine an established therapeutic range (20-50 ng/ml) is proposed to yield an optimal response and minimize side effects.

Characterization of [(3) H]LS-3-134, a novel arylamide phenylpiperazine D3 dopamine receptor selective radioligand

LS-3-134 is a substituted N-phenylpiperazine derivative that has been reported to exhibit: (i) high-affinity binding (Ki value 0.2 nM) at human D3 dopamine receptors, (ii) > 100-fold D3 versus D2 dopamine receptor subtype binding selectivity, and (iii) low-affinity binding (Ki  > 5000 nM) at sigma 1 and sigma 2 receptors. Based upon a forskolin-dependent activation of the adenylyl cyclase inhibition assay, LS-3-134 is a weak partial agonist at both D2 and D3 dopamine receptor subtypes (29% and 35% of full agonist activity, respectively). In this study, [(3) H]-labeled LS-3-134 was prepared and evaluated to further characterize its use as a D3 dopamine receptor selective radioligand. Kinetic and equilibrium radioligand binding studies were performed. This radioligand rapidly reaches equilibrium (10-15 min at 37°C) and binds with high affinity to both human (Kd  = 0.06 ± 0.01 nM) and rat (Kd  = 0.2 ± 0.02 nM) D3 receptors expressed in HEK293 cells. Direct and competitive radioligand binding studies using rat caudate and nucleus accumbens tissue indicate that [(3) H]LS-3-134 selectively binds a homogeneous population of binding sites with a dopamine D3 receptor pharmacological profile. Based upon these studies, we propose that [(3) H]LS-3-134 represents a novel D3 dopamine receptor selective radioligand that can be used for studying the expression and regulation of the D3 dopamine receptor subtype.

Functionally selective dopamine D₂, D₃ receptor partial agonists

Dopamine D2 receptor-promoted activation of Gα(o) over Gα(i) may increase synaptic plasticity and thereby might improve negative symptoms of schizophrenia. Heterocyclic dopamine surrogates comprising a pyrazolo[1,5-a]pyridine moiety were synthesized and investigated for their binding properties when low- to subnanomolar K(i) values were determined for D(2L), D(2S), and D3 receptors. Measurement of [(35)S]GTPγS incorporation at D(2S) coexpressed with G-protein subunits indicated significant bias for promotion of Gα(o1) over Gα(i2) coupling for several test compounds. Functionally selective D(2S) activation was most striking for the carbaldoxime 8b (Gα(o1), pEC50 = 8.87, E(max) = 65%; Gα(i2), pEC50 = 6.63, E(max) = 27%). In contrast, the investigated 1,4-disubstituted aromatic piperazines (1,4-DAPs) behaved as antagonists for β-arrestin-2 recruitment, implying significant ligand bias for G-protein activation over β-arrestin-2 recruitment at D(2S) receptors. Ligand efficacy and selectivity between D(2S) and D3 activation were strongly influenced by regiochemistry and the nature of functional groups attached to the pyrazolo[1,5-a]pyridine moiety.