Asenapine elevates cortical dopamine, noradrenaline and serotonin release. Evidence for activation of cortical and subcortical dopamine systems by different mechanisms

Potential Mechanisms for Why Not All Antipsychotics Are Able to Occupy Dopamine D3 Receptors in the Brain in vivo

Dysfunctions of the dopaminergic system are believed to play a major role in the core symptoms of schizophrenia such as positive, negative, and cognitive symptoms. The first line of treatment of schizophrenia are antipsychotics, a class of medications that targets several neurotransmitter receptors in the brain, including dopaminergic, serotonergic, adrenergic and/or muscarinic receptors, depending on the given agent. Although the currently used antipsychotics display in vitro activity at several receptors, majority of them share the common property of having high/moderate in vitro affinity for dopamine D₂ receptors (D₂Rs) and D₃ receptors (D₃Rs). In terms of mode of action, these antipsychotics are either antagonist or partial agonist at the above-mentioned receptors. Although D₂Rs and D₃Rs possess high degree of homology in their molecular structure, have common signaling pathways and similar in vitro pharmacology, they have different in vivo pharmacology and therefore behavioral roles. The aim of this review, with summarizing preclinical and clinical evidence is to demonstrate that while currently used antipsychotics display substantial in vitro affinity for both D₃Rs and D₂Rs, only very few can significantly occupy D₃Rs in vivo. The relative importance of the level of endogenous extracellular dopamine in the brain and the degree of in vitro D₃Rs receptor affinity and selectivity as determinant factors for in vivo D₃Rs occupancy by antipsychotics, are also discussed.

Sea urchin larvae utilize light for regulating the pyloric opening

BACKGROUND

Light is essential for various biological activities. In particular, visual information through eyes or eyespots is very important for most of animals, and thus, the functions and developmental mechanisms of visual systems have been well studied to date. In addition, light-dependent non-visual systems expressing photoreceptor Opsins have been used to study the effects of light on diverse animal behaviors. However, it remains unclear how light-dependent systems were acquired and diversified during deuterostome evolution due to an almost complete lack of knowledge on the light-response signaling pathway in Ambulacraria, one of the major groups of deuterostomes and a sister group of chordates.

RESULTS

Here, we show that sea urchin larvae utilize light for digestive tract activity. We found that photoirradiation of larvae induces pyloric opening even without addition of food stimuli. Micro-surgical and knockdown experiments revealed that this stimulating light is received and mediated by Go(/RGR)-Opsin (Opsin3.2 in sea urchin genomes) cells around the anterior neuroectoderm. Furthermore, we found that the anterior neuroectodermal serotoninergic neurons near Go-Opsin-expressing cells are essential for mediating light stimuli-induced nitric oxide (NO) release at the pylorus. Our results demonstrate that the light>Go-Opsin>serotonin>NO pathway functions in pyloric opening during larval stages.

CONCLUSIONS

The results shown here will lead us to understand how light-dependent systems of pyloric opening functioning via neurotransmitters were acquired and established during animal evolution. Based on the similarity of nervous system patterns and the gut proportions among Ambulacraria, we suggest the light>pyloric opening pathway may be conserved in the clade, although the light signaling pathway has so far not been reported in other members of the group. In light of brain-gut interactions previously found in vertebrates, we speculate that one primitive function of anterior neuroectodermal neurons (brain neurons) may have been to regulate the function of the digestive tract in the common ancestor of deuterostomes. Given that food consumption and nutrient absorption are essential for animals, the acquirement and development of brain-based sophisticated gut regulatory system might have been important for deuterostome evolution.

Asenapine Transdermal Patch for the Management of Schizophrenia

Purpose of Review

This is a comprehensive review of the literature regarding the use of asenapine for the treatment of schizophrenia (SZ) in adults. It covers an introduction, epidemiology, risk factors, pathophysiology, and current treatment modalities regarding SZ, provides a background on the mechanism of action of asenapine, and then reviews the existing evidence for use of asenapine in both its sublingual and transdermal formulation in the treatment of SZ.

Recent Findings

SZ is a complex and multifactorial mental disorder which is thought to combine several genetic, epigenetic, and environmental factors causing abnormalities in the dopaminergic system. Symptoms are categorized in delusions, hallucinations, disorganization, and negative presentations like affective flattening and apathy. Current treatment focuses on antipsychotic medications by means of oral administration or long-acting injection. Asenapine is a second-generation antipsychotic with 5HT-2A antagonist and 5HT-1A/1B partial agonist properties, which provides a favorable profile in targeting schizophrenic symptoms, while reducing motor side effects and improving mood and cognition. Asenapine in its sublingual formulation was FDA approved for treatment of SZ and bipolar I disorder in adults in August of 2009 and has been proven to be both effective and safe. Transdermal patch of asenapine (Secuado) was FDA approved in October of 2019, the first and only FDA approved patch for SZ in adults, which offers another strategy for treatment to improve compliance and ease of administration.

Summary

SZ is a chronic and debilitating disease which is still not well understood and comes at great cost with regards to the quality of life for patients. Medication side-effects and compliance are enormous issues which take a toll on health care systems in industrialized nations and keep patients from achieving stability with their disease. Transdermal asenapine is a new first-in-class dosage form and provides a novel modality of administration. It has been shown to be effective in reducing positive, as well as negative symptoms, while still maintaining a favorable side-effect profile.

The Effects of Antipsychotics on the Synaptic Plasticity Gene Homer1a Depend on a Combination of Their Receptor Profile, Dose, Duration of Treatment, and Brain Regions Targeted

Background: Antipsychotic agents modulate key molecules of the postsynaptic density (PSD), including the Homer1a gene, implicated in dendritic spine architecture. How the antipsychotic receptor profile, dose, and duration of administration may influence synaptic plasticity and the Homer1a pattern of expression is yet to be determined. Methods: In situ hybridization for Homer1a was performed on rat tissue sections from cortical and striatal regions of interest (ROI) after acute or chronic administration of three antipsychotics with divergent receptor profile: Haloperidol, asenapine, and olanzapine. Univariate and multivariate analyses of the effects of topography, treatment, dose, and duration of antipsychotic administration were performed. Results: All acute treatment regimens were found to induce a consistently higher expression of Homer1a compared to chronic ones. Haloperidol increased Homer1a expression compared to olanzapine in striatum at the acute time-point. A dose effect was also observed for acute administration of haloperidol. Conclusions: Biological effects of antipsychotics on Homer1a varied strongly depending on the combination of their receptor profile, dose, duration of administration, and throughout the different brain regions. These molecular data may have translational valence and may reflect behavioral sensitization/tolerance phenomena observed with prolonged antipsychotics.

Efficacy and Tolerability of Asenapine Compared with Olanzapine in Borderline Personality Disorder: An Open-Label Randomized Controlled Trial

BACKGROUND

Asenapine is a new second-generation antipsychotic that is understudied in borderline personality disorder (BPD). Only one study investigating the use of the drug in this indication (an open-label pilot study) has been conducted to date.

OBJECTIVE

The present open-label, randomized, controlled trial aimed to evaluate the efficacy and tolerability of asenapine in comparison with olanzapine, the most broadly studied antipsychotic in BPD.

METHODS

A total of 51 outpatients aged between 18 and 50 years with a diagnosis of BPD based on Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria were assigned for 12 weeks to asenapine (5-10 mg/day) or olanzapine (5-10 mg/day). Participants were assessed at baseline and after 12 weeks with the following instruments: the Clinical Global Impression Scale, Severity item (CGI-S), Hamilton Depression Rating Scale (HAM-D), Hamilton Anxiety Rating Scale (HAM-A), Social Occupational Functioning Assessment Scale (SOFAS), Borderline Personality Disorder Severity Index (BPDSI), Barratt Impulsiveness Scale, version 11 (BIS-11), Modified Overt Aggression Scale (MOAS), Self-Harm Inventory (SHI), and Dosage Record and Treatment Emergent Symptom Scale (DOTES). Analysis of variance repeated measures was performed. Intention-to-treat analysis with last observation carried forward was conducted.

RESULTS

There were 11 drop-outs (21.57%): six patients taking asenapine and five patients receiving olanzapine. Two patients who received asenapine stopped the drug, one due to oral hypoesthesia and the other due to moderate anxiety. Two patients receiving olanzapine discontinued the treatment because of significant weight gain (≥3 kg). The remaining seven drop-outs resulted from the lack of compliance with the trial prescription. Forty out of the 51 patients (78%) completed the trial: 19 patients received asenapine, while 21 patients received olanzapine. We found a significant within-subject effect (trial duration) for all rating scales, except from the HAM-D, the MOAS, and two items of the BPDSI, namely, "identity disturbance" and "parasuicidal behaviors." A significant effect between subjects was found for the two items of the BPDSI "affective instability" and "dissociation/paranoid ideation." Asenapine was found superior to olanzapine in reducing the affective instability score (P = 0.001), whereas olanzapine was found superior to asenapine in reducing dissociation/paranoid ideation (P = 0.012). However, the study was found to be underpowered to detect a difference between the drugs on the dissociation/paranoid ideation item of the BPDSI. Two patients receiving asenapine experienced akathisia and another two restlessness/anxiety, while three patients receiving olanzapine reported somnolence and two fatigue.

CONCLUSIONS

Asenapine and olanzapine were demonstrated to have a similar efficacy. While asenapine was found to be more efficacious than olanzapine in treating affective instability, olanzapine was superior to asenapine in treating paranoid ideation and dissociation. However, the study was underpowered to detect a difference between groups on the dissociation/paranoid ideation item. Both medications were well tolerated, with asenapine being related to a higher frequency of oral hypoesthesia and akathisia, and olanzapine being prone to induce weight gain. The open-label study design, lack of a placebo group, and small sample size constitute major limitations of this trial. Our findings need to be replicated in further studies. Clinical Trials Registry code: ACTRN12614000551695.

Asenapine modulates mood-related behaviors and 5-HT1A/7 receptors-mediated neurotransmission

AIM

Asenapine is a new atypical antipsychotic prescribed for the treatment of psychosis/bipolar disorders that presents higher affinity for serotonergic than dopaminergic receptors. The objective of this study was to investigate its antidepressant-like and antimanic-like properties on relevant animal models of depression and mania and to assess the acute and chronic effect of Asenapine on dorsal raphe nucleus (DRN) 5-HT cell firing activity.

METHODS

We assessed the effects of Asenapine using in vivo electrophysiological and behavioral assays in rats.

RESULTS

Behavioral experiments showed that Asenapine had no significant effect on immobility time in the forced swim test (FST) in control rats. In the ACTH-treated rats, a model of antidepressant-resistance, Asenapine failed to alter immobility time in the FST. In contrast in the sleep deprivation (SD) model of mania, acute administration of Asenapine significantly decreased the hyperlocomotion of SD rats. In the DRN, acute administration of Asenapine reduced the suppressant effect of the selective 5-HT₇ receptor agonist LP-44 and of the prototypical 5-HT_1A receptor agonist 8-OH-DPAT on 5-HT neuronal firing activity. In addition, chronic treatment with Asenapine enhanced DRN 5-HT neuronal firing and this effect was associated with an alteration of the 5-HT₇ receptor responsiveness.

CONCLUSION

These results confirm that Asenapine displays robust antimanic property and effective in vivo antagonistic activity at 5-HT_1A/7 receptors.

Dopamine D4 receptor stimulation contributes to novel object recognition: Relevance to cognitive impairment in schizophrenia

Several atypical antipsychotic drugs (APDs) have high affinity for the dopamine (DA) D₄ receptor, but the relevance to the efficacy for the treatment of cognitive impairment associated with schizophrenia (CIAS) is poorly understood. The aim of this study was to investigate the effects of D₄ receptor stimulation or blockade on novel object recognition (NOR) in normal rats and on the sub-chronic phencyclidine (PCP)-induced novel object recognition deficit. The effect of the D₄ agonist, PD168077, and the D₄ antagonist, L-745,870, were studied alone, and in combination with clozapine and lurasidone. In normal rats, L-745,870 impaired novel object recognition, whereas PD168077 had no effect. PD168077 acutely reversed the sub-chronic phencyclidine-induced novel object recognition deficit. Co-administration of a sub-effective dose (SED) of PD168077 with a sub-effective dose of lurasidone also reversed this deficit, but a sub-effective dose of PD168077 with a sub-effective dose of clozapine, a more potent D₄ antagonist than lurasidone, did not reverse the sub-chronic phencyclidine-induced novel object recognition deficit. At a dose that did not induce a novel object recognition deficit, L-745,870 blocked the ability of clozapine, but not lurasidone, to reverse the novel object recognition deficit. D₄ receptor agonism has a beneficial effect on novel object recognition in sub-chronic PCP-treated rats and augments the cognitive enhancing efficacy of an atypical antipsychotic drug that lacks affinity for the D₄ receptor, lurasidone.

Asenapine reduces anxiety-related behaviours in rat conditioned fear stress model

OBJECTIVE

Asenapine is an atypical antipsychotic that is currently available for the treatment of schizophrenia and bipolar I disorder. Although the atypical antipsychotics clozapine and olanzapine are effective for depression and anxiety in schizophrenia, as demonstrated by animal model studies, this has not been clarified for asenapine. Therefore, we compared the effects of asenapine in the conditioned fear stress model with those of clozapine and olanzapine.

METHOD

Rats were individually fear conditioned using electrical foot shock in a Skinner box. Approximately 24 h later, individual animals were returned to the same Skinner box (without electrical shock) and their freezing behaviour was observed for 5 min. Animals were treated with asenapine, clozapine, olanzapine, the 5-HT1A receptor partial agonist buspirone, or the 5-HT2C receptor antagonist SB242084 at 30 min before freezing behaviour assessment. The 5-HT1A receptor antagonist WAY100635 or the 5-HT2C receptor agonist Ro60-0175 was also used concomitantly with asenapine. The effects of asenapine, clozapine, and olanzapine on serotonin release in the rat hippocampus were also measured using in vivo microdialysis.

RESULTS

Asenapine reduced freezing behaviour, while neither clozapine nor olanzapine reduced freezing behaviour. Buspirone and SB242084 also reduced freezing behaviour. The effect of asenapine in reducing freezing behaviour was not altered by the concomitant administration of WAY100635 or Ro60-0175. Both asenapine and clozapine, but not olanzapine, increased serotonin release in the rat hippocampus.

CONCLUSION

Asenapine may have superior therapeutic effect on anxiety symptoms than other agents, although the underlying mechanism of its anxiolytic activity remains unknown.

An update of safety of clinically used atypical antipsychotics

INTRODUCTION

The atypical antipsychotic (APs) drugs have become the most widely used agents to treat a variety of psychoses because of their superiority with regard to safety and tolerability profile compared to conventional/'typical' APs.

AREAS COVERED

We aimed at providing a synthesis of most current evidence about the safety and tolerability profile of the most clinically used atypical APs so far marketed. Qualitative synthesis followed an electronic search made inquiring of the following databases: MEDLINE, Embase, PsycINFO and the Cochrane Library from inception until January 2016, combining free terms and MESH headings for the topics of psychiatric disorders and all atypical APs as following: ((safety OR adverse events OR side effects) AND (aripiprazole OR asenapine OR quetiapine OR olanzapine OR risperidone OR paliperidone OR ziprasidone OR lurasidone OR clozapine OR amisulpride OR iloperidone)).

EXPERT OPINION

A critical issue in the treatment with atypical APs is represented by their metabolic side effect profile (e.g. weight gain, lipid and glycaemic imbalance, risk of diabetes mellitus and diabetic ketoacidosis) which may limit their use in particular clinical samples. Electrolyte imbalance, ECG abnormalities and cardiovascular adverse effects may recommend a careful baseline and periodic assessments.

Asenapine in the Treatment of Acute Mania: A Real-World Observational Study With 6 Months Follow-Up

Asenapine is a second-generation antipsychotic with a unique pharmacological profile that was recently approved for the treatment of moderate/severe manic episodes. Real-world data on rapidity of action in inpatient settings are lacking.The aims of the current real-world observational study were to evaluate: (i) short-term efficacy of asenapine after 7 days (T0-T1) in patients hospitalized for a manic episode in the course of bipolar I disorder or schizoaffective disorder (group A), (ii) differences in length of stay (LoS), and (iii) rehospitalization compared to a control population (group B) with a 6-month follow-up.Twenty patients were included in each group. The mean total Young Mania Rating Scale score decreased by 12.6 (SD ±10.3; t(17) = 5.2, P < 0.005), implying a mean 37.8% improvement. A statistically significant reduction was observed for all Young Mania Rating Scale items, except for "sexual interest." The mean total BPRS score decreased by 17.2 (SD ±14.9; t(17) = 4.9, P < 0.005). A statistically significant reduction was observed for several items, including "conceptual disorganization," "grandiosity," "unusual thought content," and "excitement". Length of stay was 17.9 (SD ±9.0) days for group A and 14.7 (SD ±12.7) days for group B; the result of the Kruskal-Wallis test showed no significant differences (χ = 2.199, P = 0.138). Despite a high discontinuation rate, only 17.7% of patients in group A were rehospitalized in the following 6 months compared to 41.2% of those in group B (relative risk = 0.43, 95% confidence interval, 0.13-1.39).Findings from this small, preliminary study at least partially support the results of previous trials, confirming effectiveness and tolerability in the context of comorbidity and polypsychopharmacology.

Asenapine alters the activity of monoaminergic systems following its subacute and long-term administration: an in vivo electrophysiological characterization

Asenapine is a tetracyclic atypical antipsychotic used for treatment of schizophrenia and mania. Previous in vivo electrophysiological studies demonstrated antagonistic action of asenapine at dopamine D2, serotonin (5-HT)2A, and α2-adrenergic receptors. Here, we assessed monoamine system activities after two-day and 21-day asenapine administration at a dosage (0.1mg/kg/day) resulting in clinically relevant plasma levels. In the ventral tegmental area (VTA), asenapine increased the number of spontaneously active dopamine neurons, while firing parameters remained unchanged. Asenapine partially prevented the D2 autoreceptor-mediated inhibitory response to apomorphine after two days of administration. This effect was lost after 21 days of administration, suggesting adaptive changes leading to D2 receptor sensitization. Asenapine increased the firing activity of noradrenergic neurons in the locus coeruleus (LC) after 21, but not two days of administration. Furthermore, it potently blocked 5-HT2A receptors while α2-adrenergic receptors were unaffected by this drug regimen. Both acute and long-term asenapine administration partially blocked α2-adrenergic receptors in the CA3 region of the hippocampus, and noradrenergic tone on α1- and α2-adrenoceptors remained unchanged. In the dorsal raphe nucleus, asenapine increased the firing rate of 5-HT neurons after two, but not 21 days of administration. In addition, responsiveness of 5-HT1A autoreceptors was unaltered by asenapine. In the hippocampus, 21-day asenapine administration increased serotonergic tone by partial agonistic action on postsynaptic 5-HT1A and terminal 5-HT1B receptors. Taken together, asenapine had profound effects on both catecholamine systems, potently blocked 5-HT2A receptors, and enhanced 5-HT tone, effects that could be important in treatment of mood disorders and schizophrenia.

Progressive recruitment of cortical and striatal regions by inducible postsynaptic density transcripts after increasing doses of antipsychotics with different receptor profiles: insights for psychosis treatment

Antipsychotics may modulate the transcription of multiple gene programs, including those belonging to postsynaptic density (PSD) network, within cortical and subcortical brain regions. Understanding which brain region is activated progressively by increasing doses of antipsychotics and how their different receptor profiles may impact such an activation could be relevant to better correlate the mechanism of action of antipsychotics both with their efficacy and side effects. We analyzed the differential topography of PSD transcripts by incremental doses of two antipsychotics: haloperidol, the prototypical first generation antipsychotic with prevalent dopamine D2 receptors antagonism, and asenapine, a second generation antipsychotic characterized by multiple receptors occupancy. We investigated the expression of PSD genes involved in synaptic plasticity and previously demonstrated to be modulated by antipsychotics: Homer1a, and its related interacting constitutive genes Homer1b/c and PSD95, as well as Arc, C-fos and Zif-268, also known to be induced by antipsychotics administration. We found that increasing acute doses of haloperidol induced immediate-early genes (IEGs) expression in different striatal areas, which were progressively recruited by incremental doses with a dorsal-to-ventral gradient of expression. Conversely, increasing acute asenapine doses progressively de-recruited IEGs expression in cortical areas and increased striatal genes signal intensity. These effects were mirrored by a progressive reduction in locomotor animal activity by haloperidol, and an opposite increase by asenapine. Thus, we demonstrated for the first time that antipsychotics may progressively recruit PSD-related IEGs expression in cortical and subcortical areas when administered at incremental doses and these effects may reflect a fine-tuned dose-dependent modulation of the PSD.

Adjunctive treatment with asenapine augments the escitalopram-induced effects on monoaminergic outflow and glutamatergic neurotransmission in the medial prefrontal cortex of the rat

BACKGROUND

Substantial clinical data support the addition of low doses of atypical antipsychotic drugs to selective serotonin reuptake inhibitors (SSRIs) to rapidly enhance the antidepressant effect in treatment-resistant depression. Preclinical studies suggest that this effect is at least partly explained by an increased catecholamine outflow in the medial prefrontal cortex (mPFC).

METHODS

In the present study we used in vivo microdialysis in freely moving rats and in vitro intracellular recordings of pyramidal cells of the rat mPFC to investigate the effects of adding the novel atypical antipsychotic drug asenapine to the SSRI escitalopram with regards to monoamine outflow in the mPFC and dopamine outflow in nucleus accumbens as well as glutamatergic transmission in the mPFC.

RESULTS

The present study shows that addition of low doses (0.05 and 0.1 mg/kg) of asenapine to escitalopram (5 mg/kg) markedly enhances dopamine, noradrenaline, and serotonin release in the rat mPFC as well as dopamine release in the nucleus accumbens. Moreover, this drug combination facilitated both N-methyl-d-Aspartate (NMDA)- and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-induced currents as well as electrically evoked excitatory postsynaptic potentials in pyramidal cells of the rat mPFC.

CONCLUSIONS

Our results support the notion that the augmentation of SSRIs by atypical antipsychotic drugs in treatment-resistant depression may, at least in part, be related to enhanced catecholamine output in the prefrontal cortex and that asenapine may be clinically used to achieve this end. In particular, the subsequent activation of the D1 receptor may be of importance for the augmented antidepressant effect, as this mechanism facilitated both NMDA and AMPA receptor-mediated transmission in the mPFC. Our novel observation that the drug combination, like ketamine, facilitates glutamatergic transmission in the mPFC may contribute to explain the rapid and potent antidepressant effect obtained when atypical antipsychotic drugs are added to SSRIs.

Effect of acute asenapine treatment on Fos expression in the forebrain structures under normal conditions and mild stress preconditioning in the rat

Asenapine (ASE) is a novel atypical antipsychotic drug approved for the treatment of schizophrenia and bipolar disorder. Stress is an inseparable part of the human life, which may interfere with the therapeutic effect of different drugs. The aim of the present study was: (1) to delineate the quantitative and qualitative profiles of the ASE effect on Fos expression in the striatum, septum, nucleus accumbens, and the prefrontal cortex and (2) to find out whether a chronic unpredictable variable mild stress (CMS) preconditioning may modify the effect of acute ASE treatment. Stress paradigms included restrain, social isolation, crowding, swimming, and cold. The animals were exposed to CMS for 21 days and on the 22nd day received an injection of vehicle (saline 300 μl/rat s.c.) or ASE (0.3mg/kg s.c.). They were sacrificed 90 min after the treatments. Fos protein was visualized by avidin biotin peroxidase (ABC). Four groups of animals were investigated: controls+vehicle, controls+ASE, CMS+vehicle, and CMS+ASE. The number of Fos labeled neurons was calculated per total investigated area, which was selective for each structure, and also recalculated per unified sector. ASE treatment induced significant and very similar increase of the Fos expression in both ASE control and ASE CMS animals in comparison with saline control and CMS ones. Moreover, ASE induced regional differences in the number of Fos-positive neurons. In both ASE groups most pronounced response in the number of Fos profiles occurred in the dorsolateral striatum, ventrolateral septum, shell of the nucleus accumbens, and the medial prefrontal cortex. Mild Fos response was seen in the dorsomedial and ventromedial striatum and core of the nucleus accumbens. No response was seen in the dorsolateral septum. The present paper demonstrates for the first time the character of the Fos distribution in the forebrain structures induced by acute ASE treatment as well as ASE response to 21 days CMS preconditioning. The study provides an important comparative background that may help in the further understanding of the effect of ASE on the brain activation as well as its responsiveness to CMS challenges.

Use of asenapine as add-on therapy in the treatment of bipolar disorder: a comprehensive review and case series

INTRODUCTION

Several randomized controlled trials (RCTs), conducted in schizophrenic and bipolar patients, have documented the efficacy and tolerability of asenapine as monotherapy both for short- and long-term treatment. However, evidence on its augmentative use is more limited and related to the manic/mixed phase of bipolar disorder (BD).

AREAS COVERED

The present article reviews augmentative asenapine efficacy and safety/tolerability in the treatment of BD. It also includes some original cases of bipolar patients treated with add-on asenapine in the short- and long-term.

EXPERT OPINION

To date, only a single RCT with manic/mixed patients with partial response to mood-stabilizer monotherapy supports the efficacy and safety/tolerability of augmentative asenapine to lithium/valproate, both in acute and long-term treatment. Additionally, two case reports confirm the overall effectiveness of augmentative asenapine to clozapine and valproate. Our case series, consisting of 4 bipolar patients treated with adjunctive asenapine to mood stabilizers and atypical antipsychotics - with treatment duration ranging from 1 to 14 months - provided clinical results that are consistent with literature data. Taken as a whole, available evidence seems to support the efficacy and safety of adjunctive asenapine in bipolar patients, though additional studies with active comparators are requested to confirm the current body of evidence.

Management of schizophrenia: clinical experience with asenapine

Schizophrenia is a chronic brain disorder comprising a range of clinical features, including positive and negative symptoms, cognitive dysfunction and mood symptoms (particularly depression and anxiety). The management of schizophrenia requires effective short- and long-term treatment with antipsychotic medication that is effective across these symptom domains, while being well tolerated over the long term. Asenapine is the first tetracyclic atypical antipsychotic to be licensed in the USA and several other countries outside Europe for the acute and maintenance treatment of schizophrenia in adults. It has a unique receptor-binding profile and a broad range of therapeutic effects. Since clinical trials are conducted under strict conditions in tightly defined patient populations, evidence of an agent's efficacy and tolerability under 'real-world' clinical practice conditions is also required. As in clinical trials, real-life case reports demonstrate that asenapine is effective in treating the positive symptoms of schizophrenia, both in the acute setting and for relapse prevention. It is also effective in treating negative symptoms and shows promise in the treatment of depressive symptoms associated with schizophrenia. Asenapine has a favourable tolerability profile, having a minimal impact on weight and metabolic parameters. As such, asenapine is valuable option for the treatment of schizophrenia in adults.

Electrophysiological and neurochemical effects of long-term vagus nerve stimulation on the rat monoaminergic systems

Vagus nerve stimulation (VNS) is an adjunctive treatment for resistant epilepsy and depression. Electrophysiological recordings in the rat brain have already shown that chronic VNS increases norepinephrine (NE) neuronal firing activity and, subsequently, that of serotonin (5-HT) neurons through an activation of their excitatory α1-adrenoceptors. Long-term VNS was shown to increase the tonic activation of post-synaptic 5-HT1A receptors in the hippocampus. This study was aimed at examining the effect of VNS on extracellular 5-HT, NE and dopamine (DA) levels in different brain areas using in vivo microdialysis, on NE transmission in the hippocampus, and DA neuronal firing activity using electrophysiology. Rats were implanted with a VNS device and stimulated for 14 d with standard parameters used in treatment-resistant depression (0.25 mA, 20 Hz, 500 μs, 30 s on-5 min off). The results of the present study revealed that 2-wk VNS significantly increased extracellular NE levels in the prefrontal cortex and the hippocampus and enhanced the tonic activation of post-synaptic α2-adrenoceptors on pyramidal neurons. The electrophysiological experiments revealed a significant decrease in ventral tegmental area DA neuronal firing rate after long-term VNS; extracellular DA levels were nevertheless increased in the prefrontal cortex and nucleus accumbens. Chronic VNS significantly increased extracellular 5-HT levels in the dorsal raphe but not in the hippocampus and prefrontal cortex. In conclusion, the effect of VNS in increasing the transmission of monoaminergic systems targeted in the treatment of resistant depression should be involved, at least in part, in its antidepressant properties observed in patients not responding to many antidepressant strategies.

Asenapine for the treatment of manic and mixed episodes associated with bipolar I disorder: from clinical research to clinical practice

INTRODUCTION

Asenapine is a sublingually administered second-generation antipsychotic with proven efficacy for the treatment of moderate to severe manic episodes associated with bipolar I disorder in adults. Its relatively favorable weight and metabolic profile, as well as the lack of appreciable activity at muscarinic cholinergic receptors and the sublingual administration are of clinical interest.

AREAS COVERED

This paper comprises a review and commentary regarding the use of sublingual asenapine in the treatment of acute manic and mixed episodes of bipolar disorder. Basic principles in dosing, switching, management of side effects and co-administration with other medications are provided.

EXPERT OPINION

Asenapine displays quick and reliable effects on manic symptoms, very low risk of depressive switches, efficacy on depressive symptoms during manic and mixed episodes, usually good tolerability and continued longer-term efficacy on residual and subthreshold symptoms. The fast-dissolving sublingual route of administration may favor those who have difficulties in swallowing medications. Also, the sublingual administration reduces the risk of overdose when more than the prescribed tablets are swallowed. The relatively low metabolic risk and the lack of anticholinergic side effects contribute to making this medication a useful tool for the treatment of patients with bipolar disorder.

New serotonin/dopamine antagonists for the treatment of schizophrenia: are we making real progress?

The introduction of second-generation antipsychotics (SGAs), heralded by clozapine in 1990, represented an important advance in the pharmacologic treatment of schizophrenia. However, several recent comparative effectiveness trials found that non-clozapine SGAs provided little or no advantage in efficacy over first-generation antipsychotics, and all agents had substantial safety and tolerability concerns. Clearly, there remains a great unmet need for more effective and better-tolerated antipsychotics. Relatively potent antagonism of serotonin 5-HT2A receptors coupled with relatively weaker antagonism of dopamine D2 receptors is the central pharmacological characteristic shared by most SGAs. This profile continues to be a favored model for developing new SGAs, commonly defined as serotonin/dopamine antagonists. In the past ten years, aripiprazole, paliperidone, asenapine, iloperidone, and lurasidone have been introduced. Studies suggest that the newer agents have similar short-term efficacy to earlier serotonin/dopamine antagonists, and several demonstrate at least modest improvements in safety and tolerability profiles, particularly metabolic measures. However, as a group, the newer serotonin/dopamine antagonists are pharmacologically heterogeneous, and their side-effect burden can still be considerable. Moreover, their putative clinical advantages have not yet been well demonstrated via direct comparative studies. The absence of such evidence adds to the challenges in defining their place among more established treatment choices, or in providing clinicians with clear indications to guide treatment choices for individual patients. Long-term, head-to-head comparative studies are required to clarify the risk/benefit profiles of the newer antipsychotics and their roles in the treatment of schizophrenia.

The vigilance regulation model of affective disorders and ADHD

According to the recently proposed vigilance model of affective disorders (vigilance in the sense of "brain arousal"), manic behaviour is partly interpreted as an autoregulatory attempt to stabilise vigilance by creating a stimulating environment, and the sensation avoidance and withdrawal in Major Depressive Disorder (MDD) is seen as an autoregulatory reaction to tonically increased vigilance. Indeed, using a newly developed EEG-based algorithm, hyperstable vigilance was found in MDD, and the contrary, with rapid drops to sleep stages, in mania. Furthermore, destabilising vigilance (e.g. by sleep deprivation) triggers (hypo)mania and improves depression, whereas stabilising vigilance, e.g. by prolonged sleep, improves mania. ADHD and mania have common symptoms, and the unstable vigilance might be a common pathophysiology. There is even evidence that psychostimulants might ameliorate both ADHD and mania. Hyperactivity of the noradrenergic system could explain both the high vigilance level in MDD and, as recently argued, anhedonia and behavioural inhibition. Interestingly, antidepressants and electroconvulsions decrease the firing rate of neurons in the noradrenergic locus coeruleus, whereas many antimanic drugs have opposite effects.

Iloperidone, asenapine and lurasidone: a primer on their current status

INTRODUCTION

Three newer atypical antipsychotic drugs were FDA-approved in 2009 and 2010 in the following order: iloperidone, asenapine and lurasidone. The three drugs are indicated for the treatment of acute schizophrenia. Asenapine is also approved for treatment of manic or mixed episodes associated with bipolar I disorder, for the maintenance treatment of schizophrenia and as an adjunctive therapy with lithium or valproate for the acute treatment of manic or mixed episodes associated with bipolar I disorder in adults.

AREAS COVERED

This review compares and contrasts the current preclinical, clinical, safety and tolerability profiles of the three newer drugs, as reported in published preclinical and clinical studies, product labels, poster presentations and press releases.

EXPERT OPINION

Preclinical studies have reported that the three drugs have variable affinities for a wide range of neurotransmitter receptors, and are active in animal models predictive of antipsychotic activity. Asenapine is the first antipsychotic to be administered sublingually, whereas iloperidone requires titration to minimize orthostatic hypotension. Asenapine and lurasidone are associated with dose-related akathisia, whereas iloperidone is not. The three drugs appear to have relatively benign metabolic profiles. The availability of the three novel antipsychotics should provide additional options for improved treatment of schizophrenia and other psychotic disorders.

Asenapine: a clinical review of a second-generation antipsychotic

BACKGROUND

Schizophrenia and bipolar disorder are both prevalent types of psychiatric illness in the United States. As second-generation antipsychotics have become a more viable first-line treatment option, their use has been associated with a new era of adverse events (AEs), most notably metabolic and cardiovascular concerns. Although treatment options for schizophrenia and bipolar disorder have arguably improved, there continues to be a need for medications that achieve and maintain desired efficacy with minimal AEs.

OBJECTIVES

This article serves as a comprehensive review of the pharmacologic profile of the second-generation antipsychotic asenapine, as well as a review of its efficacy and safety profiles based on the findings from clinical trials in schizophrenia and bipolar disorder.

METHODS

Searches of Ovid MEDLINE, EMBASE, and IDIS were conducted (January 1996 to November 2011) to identify clinical studies and other primary literature sources with the following search terms: asenapine, bipolar disorder, antipsychotic, psychosis, dopamine, and schizophrenia. Only studies of asenapine and placebo and/or active-comparator arms were included.

RESULTS

The literature search yielded 67 unique articles, including review articles, which were excluded. The efficacy of asenapine was reported in 3 clinical studies in patients with schizophrenia, 1 each in acute and long-term settings, measured as significant changes in Positive and Negative Syndrome Scale scores over 6 and 52 weeks. Asenapine also had reported efficacy in the prevention of relapse in schizophrenia during a 26-week extension study. In addition, efficacy of asenapine was reported in 2 studies in acute mania as well as extension phases of both 9 and 40 weeks, as determined by significant changes in Young Mania Rating Scale scores. The most commonly reported AEs in these studies were somnolence (13%-24%), extrapyramidal symptoms (EPS) (7%-12%), and dizziness (11%).

CONCLUSIONS

The findings from multiple studies have suggested that asenapine is efficacious in the acute treatment of schizophrenia. Asenapine has reported long-term efficacy for this indication and the potential to reduce the incidence of relapse. Asenapine efficacy was also reported in the treatment of acute manic or mixed states associated with bipolar I disorder. Asenapine had an acceptable safety profile across the different disease states studied, although it was not devoid of metabolic and EPS-related AEs.

Spontaneous object recognition and its relevance to schizophrenia: a review of findings from pharmacological, genetic, lesion and developmental rodent models

RATIONALE

Spontaneous (novel) object recognition (SOR) is one of the most widely used rodent behavioural tests. The opportunity for rapid data collection has made SOR a popular choice in studies that explore cognitive impairment in rodent models of schizophrenia, and that test the efficacy of drugs intended to reverse these deficits.

OBJECTIVES

We provide an overview of the many recent studies that have used SOR to explore the mnemonic effects of manipulation of the key transmitter systems relevant to schizophrenia-the dopamine, glutamate, GABA, acetylcholine, serotonin and cannabinoid systems-alone or in combination. We also review the use of SOR in studying memory in genetically modified mouse models of schizophrenia, as well as in neurodevelopmental and lesion models. We end by discussing the construct and predictive validity, and translational relevance, of SOR with respect to cognitive impairment in schizophrenia.

RESULTS

Perturbation of the dopamine or glutamate systems can generate robust and reliable impairment in SOR. Impaired performance is also seen following antagonism of the muscarinic acetylcholine system, or exposure to cannabinoid agonists. Cognitive enhancement has been reported using alpha7-nicotinic acetylcholine receptor agonists and 5-HT(6) antagonists. Among non-pharmacological models, neonatal ventral hippocampal lesions and maternal immune activation can impair SOR, while mixed results have been obtained with mice carrying mutations in schizophrenia risk-associated genes, including neuregulin and COMT.

CONCLUSIONS

While SOR is not without its limitations, the task represents a useful method for studying manipulations with relevance to cognitive impairment in schizophrenia, as well as the interactions between them.

Asenapine effects on cognitive and monoamine dysfunction elicited by subchronic phencyclidine administration

PURPOSE

Repeated, intermittent administration of the psychotropic NMDA antagonist phencyclidine (PCP) to laboratory animals causes impairment in cognitive and executive functions, modeling important sequelae of schizophrenia; these effects are thought to be due to a dysregulation of neurotransmission within the prefrontal cortex. Atypical antipsychotic drugs have been reported to have measurable, if incomplete, effects on cognitive dysfunction in this model, and these effects may be due to their ability to normalize a subset of the physiological deficits occurring within the prefrontal cortex. Asenapine is an atypical antipsychotic approved in the US for the treatment of schizophrenia and for the treatment, as monotherapy or adjunctive therapy to lithium or valproate, of acute manic or mixed episodes associated bipolar I disorder. To understand its cognitive and neurochemical actions more fully, we explored the effects of short- and long-term dosing with asenapine on measures of cognitive and motor function in normal monkeys and in those previously exposed for 2 weeks to PCP; we further studied the impact of treatment with asenapine on dopamine and serotonin turnover in discrete brain regions from the same cohort.

METHODS

Monkeys were trained to perform reversal learning and object retrieval procedures before twice daily administration of PCP (0.3 mg/kg intra-muscular) or saline for 14 days. Tests confirmed cognitive deficits in PCP-exposed animals before beginning twice daily administration of saline (control) or asenapine (50, 100, or 150 μg/kg, intra-muscular). Dopamine and serotonin turnover were assessed in 15 specific brain regions by high-pressure liquid chromatography measures of the ratio of parent amine to its major metabolite.

RESULTS

On average, PCP-treated monkeys made twice as many errors in the reversal task as did control monkeys. Asenapine facilitated reversal learning performance in PCP-exposed monkeys, with improvements at trend level after 1 week of administration and reaching significance after 2-4 weeks of dosing. In week 4, the improvement with asenapine 150 μg/kg (p = 0.01) rendered the performance of PCP-exposed monkeys indistinguishable from that of normal monkeys without compromising fine motor function. Asenapine administration (150 μg/kg twice daily) produced an increase in dopamine and serotonin turnover in most brain regions of control monkeys and asenapine (50-150 μg/kg) increased dopamine and serotonin turnover in several brain regions of subchronic PCP-treated monkeys. No significant changes in the steady-state levels of dopamine or serotonin were observed in any brain region except for the central amygdala, in which a significant depletion of dopamine was observed in PCP-treated control monkeys; asenapine treatment reversed this dopamine depletion. A significant decrease in serotonin utilization was observed in the orbitofrontal cortex and nucleus accumbens in PCP monkeys, which may underlie poor reversal learning. In the same brain regions, dopamine utilization was not affected. Asenapine ameliorated this serotonin deficit in a dose-related manner that matched its efficacy for reversing the cognitive deficit.

CONCLUSIONS

In this model of cognitive dysfunction, asenapine produced substantial gains in executive functions that were maintained with long-term administration. The cognition-enhancing effects of asenapine and the neurochemical changes in serotonin and dopamine turnover seen in this study are hypothesized to be primarily related to its potent serotonergic and noradrenergic receptor binding properties, and support the potential for asenapine to reduce cognitive dysfunction in patients with schizophrenia and bipolar disorder.

Treatment strategies for dosing the second generation antipsychotics

BACKGROUND

The second generation antipsychotics now have clinical approvals for the treatment of schizophrenia, bipolar depression, bipolar mania, autism, major depressive disorder and are used furthermore off-label to treat other mental disorders. Each agent is unique in its pharmacodynamic profile and allows for unique dosing strategies to be employed when treating these different disorders.

AIMS

To review relevant data regarding the second generation antipsychotics and their empirical dosing strategies. To further review and comment theoretically in these areas where substantial, definitive data are lacking.

MATERIALS AND METHODS

A MEDLINE and recent textbook review was conducted regarding each second generation antipsychotic and cross-referenced with searches for major mental disorders. The findings are compiled in the review below.

DISCUSSION

The second generation antipsychotics are clearly delineated in the treatment of psychosis and mania and share similar mechanisms of action to achieve these results: dopamine-2 receptor antagonism for efficacy and serotonin-2a receptor antagonism for EPS tolerability. From here, each agent has a unique pharmacodynamic and pharmacokinetic profile where some agents carry more, or less antidepressant, anxiolyic, or hypnotic profiles. Choosing an agent, and dosing it in low, middle, or high ranges may result in differential effectiveness and tolerability.

CONCLUSION

The second generation antipsychotics have many clinical applications in psychiatric practice. This article serves to review this and also suggests ways clinicians may optimize treatment based upon patient diagnosis and utilizing appropriate dosing of each individual second generation antipsychotic.

Effects of asenapine on depressive symptoms in patients with bipolar I disorder experiencing acute manic or mixed episodes: a post hoc analysis of two 3-week clinical trials

BACKGROUND

Asenapine demonstrated superiority over placebo for mania in bipolar I disorder patients experiencing acute current manic or mixed episodes in 2 randomized, placebo-and olanzapine-controlled trials. We report the results of exploratory pooled post hoc analyses from these trials evaluating asenapine's effects on depressive symptoms in patients from these trials with significant baseline depressive symptoms.

METHODS

In the original trials (A7501004 [NCT00159744], A7501005 [NCT00159796]), 977 patients were randomized to flexible-dose sublingual asenapine (10 mg twice daily on day 1; 5 or 10 mg twice daily thereafter), placebo, or oral olanzapine 5-20 mg once daily for 3 weeks. Three populations were defined using baseline depressive symptoms: (1) Montgomery-Asberg Depression Rating Scale (MADRS) total score ≥20 (n = 132); (2) Clinical Global Impression for Bipolar Disorder-Depression (CGI-BP-D) scale severity score ≥4 (n = 170); (3) diagnosis of mixed episodes (n = 302) by investigative site screening. For each population, asenapine and olanzapine were independently compared with placebo using least squares mean change from baseline on depressive symptom measures.

RESULTS

Decreases in MADRS total score were statistically greater with asenapine versus placebo at days 7 and 21 in all populations; differences between olanzapine and placebo were not significant. Decreases in CGI-BP-D score were significantly greater with asenapine versus placebo at day 7 in all categories and day 21 in population 1; CGI-BP-D score reductions were significantly greater with olanzapine versus placebo at day 21 in population 1 and day 7 in populations 2 and 3.

CONCLUSIONS

These post hoc analyses show that asenapine reduced depressive symptoms in bipolar I disorder patients experiencing acute manic or mixed episodes with clinically relevant depressive symptoms at baseline; olanzapine results appeared to be less consistent. Controlled studies of asenapine in patients with acute bipolar depression are necessary to confirm the generalizability of these findings.

Asenapine improves phencyclidine-induced object recognition deficits in the rat: evidence for engagement of a dopamine D1 receptor mechanism

RATIONALE

Cognitive deficits are common in schizophrenia. Asenapine is an atypical antipsychotic approved by the US Food and Drug Administration in adults for treatment of schizophrenia or acute treatment, as monotherapy or adjunct therapy to lithium or valproate, of manic or mixed episodes of bipolar I disorder.

OBJECTIVES

Based on the receptor pharmacology of asenapine, the current study assessed the efficacy and mechanism of action of asenapine to improve a subchronic phencyclidine (PCP)-induced deficit in visual recognition memory using the novel object recognition (NOR) paradigm in the rat, a paradigm of relevance to cognition in schizophrenia.

METHODS

Female-hooded Lister rats received vehicle or PCP (2 mg/kg, i.p.) for 7 days, followed by a 7-day washout. On the test day, rats were given asenapine (0.001-0.1 mg/kg, s.c.) alone or in combination with the D(1) receptor antagonist SCH-23390 (0.05 mg/kg, i.p.) or 5-HT(1A) receptor antagonist WAY100635 (1 mg/kg, i.p.). Time spent exploring two identical objects during a 3-min acquisition trial (followed by a 1-min intertrial interval) and then a familiar and a novel object for another 3 min (retention trial) were recorded onto videotape and scored blind.

RESULTS

In the retention trial, vehicle- but not PCP-treated animals explored the novel object significantly more than the familiar object (p < 0.001). Asenapine (0.01-0.075 mg/kg) reversed PCP-induced deficits in NOR (p < 0.01-0.001) in a dose-related manner. This effect was antagonised by SCH-23390 but not by WAY100635.

CONCLUSIONS

These results demonstrate a role for D(1) but not 5-HT(1A) receptor mechanisms in mediating the cognitive effects of asenapine in this rodent model.

Pharmacology and efficacy of asenapine for manic and mixed states in adults with bipolar disorder

Asenapine sublingual is a novel atypical antipsychotic approved in August 2009 for the acute treatment of schizophrenia, as well as for manic or mixed episodes as part of adult bipolar I disorder. Asenapine's in vitro profile is similar to other atypical antipsychotic agents insofar as there is higher affinity for serotonin 5-HT(2A) versus dopamine D(2) receptors. Asenapine exhibits a unique effect on monoamine, histamine and muscarinic receptor affinities, as well as effects on NMDA and AMPA receptors. This pharmacodynamic signature may mediate its symptom relief in positive, negative and mood symptoms, as well as conferring upon this agent an improved tolerability and safety profile when compared with some atypical agents. Asenapine has a relatively low propensity for changes in metabolic parameters, body composition, sedation/somnolence and extrapyramidal side effects, and is not associated with prolactin elevation or clinically significant electrocardiographic changes. Asenapine is available only in sublingual formulation, which has advantages (e.g., patient acceptance, compliance, difficulty swallowing) as well as disadvantages (i.e., patients are encouraged not to eat or drink within 10 min of administration). Its efficacy in mania is unequivocally established as is the sustaining of its acute antimanic effect. Its antidepressant and recurrence prevention effects in bipolar disorder are under investigation, as is its possible role in major depressive disorder.

Asenapine

Asenapine is a novel psychopharmacological agent that binds with high affinity and specificity to numerous dopamine, serotonin, noradrenaline (norepinephrine) and histamine receptor subtypes. It is being developed for the treatment of schizophrenia and bipolar mania. In two randomized, controlled trials of asenapine monotherapy and in one randomized, controlled trial of adjunctive asenapine therapy in adult patients with bipolar I disorder, sublingual asenapine produced significantly greater reductions from baseline than placebo in clinician-assessed Young Mania Rating Scale (YMRS) total score at 3 weeks. In two randomized, controlled trials in adult patients with acute schizophrenia, treatment with asenapine reduced from baseline the clinician-assessed Positive and Negative Syndrome Scale (PANSS) total score to a significantly greater extent than placebo at 6 weeks. In schizophrenic patients with predominant, persistent, negative symptoms, asenapine at 26 weeks reduced the Negative Symptom Assessment (NSA-16) total score from baseline to an extent similar to that observed with olanzapine. Sublingual asenapine was generally well tolerated in clinical trials, with most treatment-emergent adverse events being of mild to moderate severity. Incidence rates of clinically significant weight gain, extrapyramidal symptoms, hyperprolactinaemia and alterations in glucose or lipid metabolism were generally low.