The 'atypicality' of antipsychotics: a concept re-examined and re-defined

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.

Modulation of neuronal morphology by antipsychotic drug: Involvement of serotonin receptor 7

Antipsychotic drugs (APDs) are the primary pharmacological treatment for schizophrenia, a complex disorder characterized by altered neuronal connectivity. Atypical or second-generation antipsychotics, such as Risperidone (RSP) and Clozapine (CZP) predominantly block dopaminergic D2 and serotonin receptor 2A (5-HT2A) neurotransmission. Both compounds also exhibit affinity for the 5-HT7R, with RSP acting as an antagonist and CZP as an inverse agonist. Our study aimed to determine whether RSP and CZP can influence neuronal morphology through a 5-HT7R-mediated mechanism. Here, we demonstrated that CZP promotes neurite outgrowth of early postnatal cortical neurons, and the 5-HT7R mediates its effect. Conversely, RSP leads to a reduction of neurite length of early postnatal cortical neurons, in a 5-HT7R-independent way. Furthermore, we found that the effects of CZP, mediated by 5-HT7R activation, require the participation of ERK and Cdk5 kinase pathways. At the same time, the modulation of neurite length by RSP does not involve these pathways. In conclusion, our findings provide valuable insights into the morphological changes induced by these two APDs in neurons and elucidate some of the associated molecular pathways. Investigating the 5-HT7R-dependent signaling pathways underlying the neuronal morphogenic effects of APDs may contribute to the identification of novel targets for the treatment of schizophrenia.

The Natural Protoalkaloid Methyl-2-Amino-3-Methoxybenzoate (MAM) Alleviates Positive as well as Cognitive Symptoms in Rat and Mouse Schizophrenia Models

The development of new antipsychotics with pro-cognitive properties and less side effects represents a priority in schizophrenia drug research. In this study, we present for the first time a preclinical exploration of the effects of the promising natural atypical antipsychotic Methyl-2-Amino-3- Methoxybenzoate (MAM), a brain-penetrable protoalkaloid from the seed of the plant Nigella damascena. Using animal models related to hyperdopaminergic activity, namely the pharmacogenetic apomorphine (D2/D1 receptor agonist)-susceptible (APO-SUS) rat model and pharmacologically induced mouse and rat models of schizophrenia, we found that MAM reduced gnawing stereotypy and climbing behaviours induced by dopaminergic agents. This predicts antipsychotic activity. In line, MAM antagonized apomorphine-induced c-Fos and NPAS4 mRNA levels in post-mortem brain nucleus accumbens and dorsolateral striatum of APO-SUS rats. Furthermore, phencyclidine (PCP, an NMDA receptor antagonist) and 2,5-Dimethoxy-4-iodoamphetamine (DOI, a 5HT2A/2C receptor agonist) induced prepulse inhibition deficits, reflecting the positive symptoms of schizophrenia, which were rescued by treatment with MAM and atypical antipsychotics alike. Post-mortem brain immunostaining revealed that MAM blocked the strong activation of both PCP- and DOI-induced c-Fos immunoreactivity in a number of cortical areas. Finally, during a 28-day subchronic treatment regime, MAM did not induce weight gain, hyperglycemia, hyperlipidemia or hepato- and nephrotoxic effects, side effects known to be induced by atypical antipsychotics. MAM also did not show any cataleptic effects. In conclusion, its brain penetrability, the apparent absence of preclinical side effects, and its ability to antagonize positive and cognitive symptoms associated with schizophrenia make MAM an exciting new antipsychotic drug that deserves clinical testing.

Noninvasive drug adherence monitoring of antipsychotic patients via finger sweat testing

Collection of finger sweat is explored here as a rapid and convenient way of monitoring patient adherence to antipsychotic drugs. Finger sweat samples (n = 426) collected from patients receiving treatment with clozapine, quetiapine and olanzapine were analysed by liquid chromatography mass spectrometry, including a subgroup of patients with paired plasma samples. Finger sweat samples were also analysed from a negative control group and patients who had handled antipsychotic medication only. The finger sweat test (based on the detection of parent drug in one donated sample) was 100% effective in monitoring adherence within commonly prescribed dosing ranges. In comparison to participants who handled the medication only, the test could distinguish between contact and administration through monitoring of the drug metabolite, or the level of parent drug. Additionally, in a subgroup of patients prescribed clozapine, a statistically significant correlation was observed between the mass of parent drug in finger sweat and plasma concentration. The finger sweat technology shows promise as a dignified, noninvasive method to monitor treatment adherence in patients taking antipsychotics.

Schizophrenia Synaptic Pathology and Antipsychotic Treatment in the Framework of Oxidative and Mitochondrial Dysfunction: Translational Highlights for the Clinics and Treatment

Schizophrenia is a worldwide mental illness characterized by alterations at dopaminergic and glutamatergic synapses resulting in global dysconnectivity within and between brain networks. Impairments in inflammatory processes, mitochondrial functions, energy expenditure, and oxidative stress have been extensively associated with schizophrenia pathophysiology. Antipsychotics, the mainstay of schizophrenia pharmacological treatment and all sharing the common feature of dopamine D2 receptor occupancy, may affect antioxidant pathways as well as mitochondrial protein levels and gene expression. Here, we systematically reviewed the available evidence on antioxidants' mechanisms in antipsychotic action and the impact of first- and second-generation compounds on mitochondrial functions and oxidative stress. We further focused on clinical trials addressing the efficacy and tolerability of antioxidants as an augmentation strategy of antipsychotic treatment. EMBASE, Scopus, and Medline/PubMed databases were interrogated. The selection process was conducted in respect of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. Several mitochondrial proteins involved in cell viability, energy metabolism, and regulation of oxidative systems were reported to be significantly modified by antipsychotic treatment with differences between first- and second-generation drugs. Finally, antioxidants may affect cognitive and psychotic symptoms in patients with schizophrenia, and although the evidence is only preliminary, the results indicate that further studies are warranted.

Molecular Imaging of Dopamine Partial Agonists in Humans: Implications for Clinical Practice

Positron emission tomography (PET) has been used since the late 1980s for the assessment of relationships between occupancy of D_2/3 receptors by antipsychotic drugs in the human brain and the clinical effects and side effects of these compounds in patients. It is now well established for most D_2/3 antagonists, both of the first and the second generation, that the ideal occupancy of their target receptors is between approximately 65 and 80%. If the occupancy is below 65%, the probability of treatment response is reduced, if the occupancy is higher than 80%, the risk for extrapyramidal side-effects increases substantially. However, partial agonist antipsychotics behave different from these rules. It has been shown for all three available drugs of this class (aripiprazole, brexpiprazole, cariprazine) that, due to their special pharmacology, a very high target engagement (>90%) not only is not harmful but represents a prerequisite for antipsychotic efficacy. The available PET studies for these drugs are reviewed in this work. It is demonstrated that optimal plasma levels for partial agonist antipsychotics can be derived from these studies, which can guide individual treatment in routine patient care.

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.

Pharmacogenetics of Antipsychotic Treatment in Schizophrenia

Antipsychotics are the mainstay treatment for schizophrenia. There is large variability between individuals in their response to antipsychotics, both in efficacy and adverse effects of treatment. While the source of interindividual variability in antipsychotic response is not completely understood, genetics is a major contributing factor. The identification of pharmacogenetic markers that predict antipsychotic efficacy and adverse reactions is a growing area of research and holds the potential to replace the current trial-and-error approach to treatment selection in schizophrenia with a personalized medicine approach.In this chapter, we provide an overview of the current state of pharmacogenetics in schizophrenia treatment. The most promising pharmacogenetic findings are presented for both antipsychotic response and commonly studied adverse reactions. The application of pharmacogenetics to schizophrenia treatment is discussed, with an emphasis on the clinical utility of pharmacogenetic testing and directions for future research.

Tools for optimising pharmacotherapy in psychiatry (therapeutic drug monitoring, molecular brain imaging and pharmacogenetic tests): focus on antidepressants

Objectives: More than 40 drugs are available to treat affective disorders. Individual selection of the optimal drug and dose is required to attain the highest possible efficacy and acceptable tolerability for every patient.Methods: This review, which includes more than 500 articles selected by 30 experts, combines relevant knowledge on studies investigating the pharmacokinetics, pharmacodynamics and pharmacogenetics of 33 antidepressant drugs and of 4 drugs approved for augmentation in cases of insufficient response to antidepressant monotherapy. Such studies typically measure drug concentrations in blood (i.e. therapeutic drug monitoring) and genotype relevant genetic polymorphisms of enzymes, transporters or receptors involved in drug metabolism or mechanism of action. Imaging studies, primarily positron emission tomography that relates drug concentrations in blood and radioligand binding, are considered to quantify target structure occupancy by the antidepressant drugs in vivo. Results: Evidence is given that in vivo imaging, therapeutic drug monitoring and genotyping and/or phenotyping of drug metabolising enzymes should be an integral part in the development of any new antidepressant drug.Conclusions: To guide antidepressant drug therapy in everyday practice, there are multiple indications such as uncertain adherence, polypharmacy, nonresponse and/or adverse reactions under therapeutically recommended doses, where therapeutic drug monitoring and cytochrome P450 genotyping and/or phenotyping should be applied as valid tools of precision medicine.

Atypical Antipsychotics and Metabolic Syndrome: From Molecular Mechanisms to Clinical Differences

Atypical antipsychotics (AAPs) are commonly prescribed medications to treat schizophrenia, bipolar disorders and other psychotic disorders. However, they might cause metabolic syndrome (MetS) in terms of weight gain, dyslipidemia, type 2 diabetes (T2D), and high blood pressure, which are responsible for reduced life expectancy and poor adherence. Importantly, there is clear evidence that early metabolic disturbances can precede weight gain, even if the latter still remains the hallmark of AAPs use. In fact, AAPs interfere profoundly with glucose and lipid homeostasis acting mostly on hypothalamus, liver, pancreatic β-cells, adipose tissue, and skeletal muscle. Their actions on hypothalamic centers via dopamine, serotonin, acetylcholine, and histamine receptors affect neuropeptides and 5'AMP-activated protein kinase (AMPK) activity, thus producing a supraphysiological sympathetic outflow augmenting levels of glucagon and hepatic glucose production. In addition, altered insulin secretion, dyslipidemia, fat deposition in the liver and adipose tissues, and insulin resistance become aggravating factors for MetS. In clinical practice, among AAPs, olanzapine and clozapine are associated with the highest risk of MetS, whereas quetiapine, risperidone, asenapine and amisulpride cause moderate alterations. The new AAPs such as ziprasidone, lurasidone and the partial agonist aripiprazole seem more tolerable on the metabolic profile. However, these aspects must be considered together with the differences among AAPs in terms of their efficacy, where clozapine still remains the most effective. Intriguingly, there seems to be a correlation between AAP's higher clinical efficacy and increase risk of metabolic alterations. Finally, a multidisciplinary approach combining psychoeducation and therapeutic drug monitoring (TDM) is proposed as a first-line strategy to avoid the MetS. In addition, pharmacological treatments are discussed as well.

Effect of pharmacological manipulations on Arc function

Activity-regulated cytoskeleton-associated protein (Arc) is a brain-enriched immediate early gene that regulates important mechanisms implicated in learning and memory. Arc levels are controlled through a balance of induction and degradation in an activity-dependent manner. Arc further undergoes multiple post-translational modifications that regulate its stability, localization and function. Recent studies demonstrate that these features of Arc can be pharmacologically manipulated. In this review, we discuss some of these compounds, with an emphasis on drugs of abuse and psychotropic drugs. We also discuss inflammatory states that regulate Arc.

Targeting the 5-HT system: Potential side effects

Targeting the serotonin (5-HT) system is no simple task: there are at least 15 5-HT receptors, in addition to a number of transporters and metabolizing enzymes. Multiple 5-HT receptor variants exist due to genetic variations and/or post translational modifications, splice variants or editing variants. Some receptors may form homo and heteromers. The 5-HT system is targeted by multiple drugs to treat a variety of diseases. Given the homology amongst the 5-HT and neighbouring receptor classes, only few drugs are actually selective for a single target. In fact, many 5-HT drugs act on a combination of targets, i.e. several receptors and/or transporters or enzymes. For instance, a number of antidepressants or antipsychotics act on 5-HT and other transmitter systems. Recently developed drugs may show target selectivity by design, based on the current state of knowledge, whereas many older compounds hit multiple targets since they were developed using phenotypic screens, as was done well into the 1980's. Ergot analogues, antipsychotics or antidepressants, fall into this category. As our knowledge developed over the last 25-30 years, some targets have very well-defined liabilities: for instance, 5HT_2B or 5-HT_2A receptor agonists, will produce valvulopathies or hallucinations, respectively, whereas 5-HT₃ receptor antagonists, may lead to constipation. This short review will be limited in scope as there are multiple targets and even more compounds to discuss. This article is part of the special issue entitled 'Serotonin Research: Crossing Scales and Boundaries'.

Molecular imaging of schizophrenia: Neurochemical findings in a heterogeneous and evolving disorder

The past four decades have seen enormous efforts placed on a search for molecular markers of schizophrenia using positron emission tomography (PET) and single photon emission computed tomography (SPECT). In this narrative review, we cast a broad net to define and summarize what researchers have learned about schizophrenia from molecular imaging studies. Some PET studies of brain energy metabolism with the glucose analogue FDGhave have shown a hypofrontality defect in patients with schizophrenia, but more generally indicate a loss of metabolic coherence between different brain regions. An early finding of significantly increased striatal trapping of the dopamine synthesis tracer FDOPA has survived a meta-analysis of many replications, but the increase is not pathognomonic of the disorder, since one half of patients have entirely normal dopamine synthesis capacity. Similarly, competition SPECT studies show greater basal and amphetamine-evoked dopamine occupancy at post-synaptic dopamine D_2/3 receptors in patients with schizophrenia, but the difference is likewise not pathognomonic. We thus propose that molecular imaging studies of brain dopamine indicate neurochemical heterogeneity within the diagnostic entity of schizophrenia. Occupancy studies have established the relevant target engagement by antipsychotic medications at dopamine D_2/3 receptors in living brain. There is evidence for elevated frontal cortical dopamine D₁ receptors, especially in relation to cognitive deficits in schizophrenia. There is a general lack of consistent findings of abnormalities in serotonin markers, but some evidence for decreased levels of nicotinic receptors in patients. There are sparse and somewhat inconsistent findings of reduced binding of muscarinic, glutamate, and opioid receptors ligands, inconsistent findings of microglial activation, and very recently, evidence of globally reduced levels of synaptic proteins in brain of patients. One study reports a decline in histone acetylase binding that is confined to the dorsolateral prefrontal cortex. In most contexts, the phase of the disease and effects of past or present medication can obscure or confound PET and SPECT findings in schizophrenia.

Schizophrenia; A Review on Promising Drug Delivery Systems

Background:

Schizophrenia belongs to mental illnesses affecting 1% of the worldwide population. Its therapy is still unmet; thus, researchers aimed to develop new pharmacological molecules which can improve its management.

Methods:

Moreover, the current typical and atypical antipsychotics should be formulated in more efficacious systems that can deliver the drug in the brain with as few side effects as possible. Further, the development of long-acting efficient drug delivery systems could be significant in minimizing frequent dosing which is nonpreferred to schizophrenics.

Results:

Herein, authors focused on current developments of antipsychotic medications used in schizophrenia management. Various studies, which include the use of first and second-generation antipsychotics, were analyzed according to their efficacy. In fact, in this review, oral, injectable, transdermal and intranasal formulations entrapped antipsychotics are presented to be valuable guidance for scientists to formulate more effective drug delivery systems for schizophrenic patients.

Conclusions:

This review aimed to assist researchers working on schizophrenia management by summarizing current medications and newly synthesized drug delivery systems recently found in the literature.

Voltammetric Analysis of Atypical Antipsychotic Drugs with Solid Electrodes

Background:

Qualitative and quantitative analysis of atypical antipsychotic drugs used for the treatment of schizophrenia, depression, anxiety, and bipolar disorder obtaining satisfactory results can be ensured by voltammetric techniques. The aim of this review is to present the application of voltammetric techniques developed for the determination of the atypical antipsychotic drugs, which are amisulpride, aripiprazole, clozapine, olanzapine, quetiapine fumarate, risperidone, sertindole, and ziprasidone, in pharmaceutical dosage forms and biological samples.

Methods:

Studies in the literature published between 2004 and 2017 based on the voltammetric determination of atypical antipsychotic drugs were gathered using scientific databases. The results obtained from these studies were combined and interpreted.

Results:

oltammetric techniques applied for the sensitive determination of trace amounts of the selected atypical antipsychotic drugs in their pharmaceutical dosage forms and biological fluids were compared. The best analysis conditions were obtained after the optimization of some parameters such as buffer type, pH, and scan rate. For diffusion controlled electrode processes, it was observed that differential pulse and square wave voltammetry methods were generally used for the sensitive quantitative determination of the drugs, whereas stripping methods were used for the adsorption controlled electrode processes. Detection limits were between 1.53×10-3 µM for clozapine and 0.97 µM for risperidone.

Conclusion:

The electrodes used in the studies showed high selectivity, sensitivity, and good accuracy with precision. The developed methods were also applied to pharmaceutical preparations of the drugs and biological fluids with satisfactory results, without any interference from inactive excipients.

Controversies in bipolar disorder; role of second-generation antipsychotic for maintenance therapy

In this narrative review, we discuss use of second-generation antipsychotics (SGAs) in maintenance treatment of bipolar disorder. We compare their use to historically more established treatments (particularly lithium, the gold standard). To compare we review evidence on efficacy, effectiveness and tolerability across illness poles, possible mechanisms of treatment response, guidance given by guideline groups and pragmatic clinical considerations. We then illustrate the controversies in maintenance antipsychotic use, with the example of first episode mania and its treatment within first episode psychosis services. Finally, we make suggestions for future studies to unpick these differences.

[Translational behavioral research using common marmosets in the psychiatric field]

The drug discovery activities for novel compounds with the superior efficacies to current drugs have been largely unsuccessful in the psychiatric field. One of the main reasons is the lack of appropriate behavioral assays and animal models for psychiatric disorders. Since the prefrontal cortex has great roles in their pathophysiology, non-human primate common marmosets with the well-developed prefrontal cortex would be useful as experimental animals in the future translational research. To measure objectively and quantitatively the psychiatric symptoms like motivational deficits, negative affective bias and cognitive impairments in patients with schizophrenia or major depressive disorder, the clinical laboratory tasks have been developed. The development of marmoset behavioral paradigms, which may correspond to the clinical laboratory tasks, have been progressed for the translational research. On the other hand, there are still limitations to develop the marmoset models resembling the pathophysiology of psychiatric disorders. We review the current state and future perspective of translational behavioral research using marmosets.

An Overview of Animal Models Related to Schizophrenia

Schizophrenia is a heterogeneous psychiatric disorder that is poorly treated with current therapies. In this brief review, we provide an update regarding the use of animal models to study schizophrenia in an attempt to understand its aetiology and develop novel therapeutic strategies. Tremendous progress has been made developing and validating rodent models that replicate the aetiologies, brain pathologies, and behavioural abnormalities associated with schizophrenia in humans. Here, models are grouped into 3 categories-developmental, drug induced, and genetic-to reflect the heterogeneous risk factors associated with schizophrenia. Each of these models is associated with varied but overlapping pathophysiology, endophenotypes, behavioural abnormalities, and cognitive impairments. Studying schizophrenia using multiple models will permit an understanding of the core features of the disease, thereby facilitating preclinical research aimed at the development and validation of better pharmacotherapies to alter the progression of schizophrenia or alleviate its debilitating symptoms.

Trace Amines and Their Receptors

Trace amines are endogenous compounds classically regarded as comprising β-phenylethyalmine, p-tyramine, tryptamine, p-octopamine, and some of their metabolites. They are also abundant in common foodstuffs and can be produced and degraded by the constitutive microbiota. The ability to use trace amines has arisen at least twice during evolution, with distinct receptor families present in invertebrates and vertebrates. The term "trace amine" was coined to reflect the low tissue levels in mammals; however, invertebrates have relatively high levels where they function like mammalian adrenergic systems, involved in "fight-or-flight" responses. Vertebrates express a family of receptors termed trace amine-associated receptors (TAARs). Humans possess six functional isoforms (TAAR1, TAAR2, TAAR5, TAAR6, TAAR8, and TAAR9), whereas some fish species express over 100. With the exception of TAAR1, TAARs are expressed in olfactory epithelium neurons, where they detect diverse ethological signals including predators, spoiled food, migratory cues, and pheromones. Outside the olfactory system, TAAR1 is the most thoroughly studied and has both central and peripheral roles. In the brain, TAAR1 acts as a rheostat of dopaminergic, glutamatergic, and serotonergic neurotransmission and has been identified as a novel therapeutic target for schizophrenia, depression, and addiction. In the periphery, TAAR1 regulates nutrient-induced hormone secretion, suggesting its potential as a novel therapeutic target for diabetes and obesity. TAAR1 may also regulate immune responses by regulating leukocyte differentiation and activation. This article provides a comprehensive review of the current state of knowledge of the evolution, physiologic functions, pharmacology, molecular mechanisms, and therapeutic potential of trace amines and their receptors in vertebrates and invertebrates.

Comparative Efficacy and Safety of Long-acting Injectable and Oral Second-generation Antipsychotics for the Treatment of Schizophrenia: A Systematic Review and Meta-analysis

We aimed to compare the efficacy and safety of long-acting injectable (LAI) and oral second-generation antipsychotics (SGAs) in treating schizophrenia by performing a systematic review and meta-analysis. MEDLINE, EMBASE, PsycINFO, CINAHL, and the Cochrane Library, as well as five Korean databases, were systemically searched to identify studies published from 2000 to 16 April 2015, which compared the efficacy and safety of LAI and oral SGAs. Using data from randomized controlled trials (RCTs), meta-analyses were conducted. In addition, the GRADE (the Grading of Recommendations, Assessment, Development and Evaluation) approach was applied to explicitly assess the quality of the evidence. A total of 30 studies including 17 RCTs and 13 observational studies were selected. The group treated with LAI SGAs was characterized by significantly lower relapse rates, longer times to relapse and fewer hospital days, but also by a higher occurrence of extrapyramidal syndrome and prolactin-related symptoms than that in the group treated with oral SGAs. Our findings demonstrate that there is moderate to high level of evidence suggesting that in the treatment of schizophrenia, LAI SGAs have higher efficacy and are associated with higher rates of extrapyramidal syndrome and prolactin-related symptoms. Additionally, the use of LAI SGAs should be combined with appropriate measures to reduce dopamine D₂ antagonism-related symptoms.

Morin Attenuates Neurochemical Changes and Increased Oxidative/Nitrergic Stress in Brains of Mice Exposed to Ketamine: Prevention and Reversal of Schizophrenia-Like Symptoms

Previous studies have revealed that morin (MOR), a neuroactive bioflavonoid, with proven psychotropic and neuroprotective properties reduced schizophrenic-like behaviors in mice. This study further evaluated the ability of MOR to prevent and reverse ketamine-induced schizophrenic-like behaviors and the underlying neurochemical changes and increased oxidative/nitrergic stress in mice. In the preventive protocol, mice received intraperitoneal injection of MOR (100 mg/kg), reference antipsychotic drugs [haloperidol (1 mg/kg), risperidone (0.5 mg/kg)], or saline daily for 14 consecutive days prior to i.p. injection of ketamine (KET) (20 mg/kg/day) from the 8th to the 14th day. In the reversal protocol, the animals received KET or saline for 14 days prior to MOR, haloperidol, risperidone, or saline treatments. Schizophrenic-like behaviors: positive (open-field test), negative (social-interaction test) and cognitive (Y-maze test) symptoms were evaluated. Thereafter, the brain levels of dopamine, glutamate, 5-hydroxytryptamine and acetyl-cholinesterase, as well as biomarkers of oxidative/nitrergic stress were measured in the striatum, prefrontal-cortex (PFC) and hippocampus (HC). Morin prevented and reversed KET-induced hyperlocomotion, social and cognitive deficits. Also, MOR or risperidone attenuated altered dopaminergic, glutamatergic, 5-hydroxytryptaminergic and cholinergic neurotransmissions in brain region-dependent manner. The increased malondialdehyde and nitrite levels accompanied by decreased glutathione concentrations in the striatum, PFC and HC in KET-treated mice were significantly attenuated by MOR or risperidone. Taken together, these findings suggest that the anti-schizophrenic-like activity of MOR may be mediated via mechanisms related to attenuation of neurochemical changes and oxidative/nitrergic alterations in mice.

Molecular targets of atypical antipsychotics: From mechanism of action to clinical differences

The introduction of atypical antipsychotics (AAPs) since the discovery of its prototypical drug clozapine has been a revolutionary pharmacological step for treating psychotic patients as these allow a significant recovery not only in terms of hospitalization and reduction in symptoms severity, but also in terms of safety, socialization and better rehabilitation in the society. Regarding the mechanism of action, AAPs are weak D₂ receptor antagonists and they act beyond D₂ antagonism, involving other receptor targets which regulate dopamine and other neurotransmitters. Consequently, AAPs present a significant reduction of deleterious side effects like parkinsonism, hyperprolactinemia, apathy and anhedonia, which are all linked to the strong blockade of D₂ receptors. This review revisits previous and current findings within the class of AAPs and highlights the differences in terms of receptor properties and clinical activities among them. Furthermore, we propose a continuum spectrum of "atypia" that begins with risperidone (the least atypical) to clozapine (the most atypical), while all the other AAPs fall within the extremes of this spectrum. Clozapine is still considered the gold standard in refractory schizophrenia and in psychoses present in Parkinson's disease, though it has been associated with adverse effects like agranulocytosis (0.7%) and weight gain, pushing the scientific community to find new drugs as effective as clozapine, but devoid of its side effects. To achieve this, it is therefore imperative to characterize and compare in depth the very complex molecular profile of AAPs. We also introduce relatively new concepts like biased agonism, receptor dimerization and neurogenesis to identify better the old and new hallmarks of "atypia". Finally, a detailed confrontation of clinical differences among the AAPs is presented, especially in relation to their molecular targets, and new means like therapeutic drug monitoring are also proposed to improve the effectiveness of AAPs in clinical practice.

Extract of Synedrella nodiflora (L) Gaertn exhibits antipsychotic properties in murine models of psychosis

BACKGROUND

The hydro-ethanolic whole plant extract of Synedrella nodiflora (SNE) has demonstrated anticonvulsant, sedative and analgesic effects. Preliminary studies conducted in animals, SNE significantly decreased stereotypic behaviours suggesting antipsychotic potential. Coupled with the central nervous system depressant effects of SNE, we hypothesized that it may have utility in the management of psychosis. The present study therefore investigated the antipsychotic potential of the SNE in several murine models of psychosis.

METHOD

The primary central nervous system activities of SNE (30-3000 mg/kg, p.o) were investigated using the Irwin's test. The novelty-induced rearing, locomotion and stereotypy counts provoked by SNE (100-1000 mg/kg, p.o) were conducted using the open-field paradigm. The antipsychotic test models used in the screening of SNE (100-1000 mg/kg, p.o) included apomorphine-induced stereotypy, rearing, locomotion and cage climbing activities. The combined effects of a low dose of SNE (100 mg/kg) with various doses of haloperidol and chlorpromazine were analysed using the apomorphine-induced cage climbing and stereotypy, respectively. The ability of SNE to cause catalepsy in naïve mice as well as its effect on haloperidol-induced catalepsy was assessed.

RESULTS

SNE showed acetylcholine-like and serotonin-like activities in the Irwin test, with sedation occurring at high doses. SNE significantly reduced the frequencies of novelty- and apomorphine-induced rearing and locomotion; stereotypy behaviour and the frequency and duration of apomorphine-induced cage climbing in mice. In all the tests performed, SNE was less potent than the reference drugs used (chlorpromazine and haloperidol). In addition, SNE potentiated the effects of haloperidol and chlorpromazine on apomorphine-induced cage climbing and stereotypy activities in mice.

CONCLUSION

SNE, while exhibiting antipsychotic properties itself, can also potentiate the antipsychotic effects of chlorpromazine and haloperidol.

Receptor visualization and the atomic bomb. A historical account of the development of the chemical neuroanatomy of receptors for neurotransmitters and drugs during the Cold War

This is a historical account of how receptors for neurotransmitters and drugs got to be seen at the regional, cellular, and subcellular levels in brain, in the years going from the end of the World War II until the collapse of the Soviet Union, the Cold War (1945-1991). The realization in the US of the problem of mental health care, as a consequence of the results of medical evaluation for military service during the war, let the US Government to act creating among other things the National Institute for Mental Health (NIMH). Coincident with that, new drug treatments for these disorders were introduced. War science also created an important number of tools and instruments, such as the radioisotopes, that played a significant role in the development of our story. The scientific context was marked by the development of Biochemistry, Molecular Biology and the introduction in the early 80's of the DNA recombinant technologies. The concepts of chemical neurotransmission in the brain and of receptors for drugs and transmitters, although proposed before the war, where not generally accepted. Neurotransmitters were identified and the mechanisms of biosynthesis, storage, release and termination of action by mechanisms such as reuptake, elucidated. Furthermore, the synapse was seen with the electron microscope and more important for our account, neurons and their processes visualized in the brain first by fluorescence histochemistry, then using radioisotopes and autoradiography, and later by immunohistochemistry (IHC), originating the Chemical Neuroanatomy. The concept of chemical neurotransmission evolved from the amines, expanded to excitatory and inhibitory amino acids, then to neuropeptides and finally to gases and other "atypical" neurotransmitters. In addition, coexpression of more than one transmitter in a neuron, changed the initial ideas of neurotransmission. The concept of receptors for these and other messengers underwent a significant evolution from an abstract chemical concept to their physical reality as gene products. Important steps were the introduction in the 70's of radioligand binding techniques and the cloning of receptor genes in the 80's. Receptors were first visualized using radioligands and autoradiography, and analyzed with the newly developed computer-assisted image analysis systems. Using Positron Emission Tomography transmitters and receptors were visualized in living human brain. The cloning of receptor genes allowed the use of in situ hybridization histochemistry and immunohistochemistry to visualize with the light and electron microscopes the receptor mRNAs and proteins. The results showed the wide heterogeneity of receptors and the diversity of mode of signal transmission, synaptic and extra-synaptic, again radically modifying the early views of neurotransmission. During the entire period the interplay between basic science and Psychopharmacology and Psychiatry generated different transmitter or receptor-based theories of brain drug action. These concepts and technologies also changed the way new drugs were discovered and developed. At the end of the period, a number of declines in these theories, the use of certain tools and the ability to generate new diagnostics and treatments, the end of an era and the beginning of a new one in the research of how the brain functions.

Extrapyramidal Symptoms Probably Related to Risperidone Treatment: A Case Series

BACKGROUND

Atypical antipsychotics, like risperidone purportedly, score over their typical counterparts in terms of their lower propensity toward producing extrapyramidal symptoms (EPS). However, recent studies have furnished evidence to the contrary. Hereby, we present a case series implicating risperidone as the causative agent for EPS.

METHODS

As a part of the pharmacovigilance programme of India, the authors have assessed 10 physician-reported cases of EPS among the 1,830 patients who were prescribed risperidone within the time period of January 2012-December 2014 in a tertiary care hospital in South India. Causality, severity, and preventability assessments of adverse reaction were done as per Naranjo's, Hartwig's, and Thornton'scale respectively.

RESULTS

Of the 10 cases, a dose-dependent occurrence of EPS was noted in all and the time duration for development of EPS ranged from 1 week to 2 years. Four patients developed EPS at a dose of 6-8 mg, 4 developed at a dose of 4-6 mg, and the remaining 2 developed at 2 and 1 mg.

CONCLUSION

A strong temporal correlation between risperidone and EPS was noted in all cases. High doses produced EPS early, whereas moderate to low doses produced EPS at a later date. Thus, cautious use and close monitoring are warranted in the chronic use of risperidone.

Antipsychotic combinations for schizophrenia

BACKGROUND

Many people with schizophrenia do not achieve a satisfactory treatment response with their initial antipsychotic drug treatment. Sometimes a second antipsychotic, in combination with the first, is used in these situations.

OBJECTIVES

To examine whether:1. treatment with antipsychotic combinations is effective for schizophrenia; and2. treatment with antipsychotic combinations is safe for the same illness.

SEARCH METHODS

We searched the Cochrane Schizophrenia Group's register which is based on regular searches of CINAHL, BIOSIS, AMED, Embase, PubMed, MEDLINE, PsycINFO, and registries of clinical trials. There are no language, time, document type, or publication status limitations for inclusion of records in the register. We ran searches in September 2010, August 2012 and January 2016. We checked for additional trials in the reference lists of included trials.

SELECTION CRITERIA

We included all randomised and quasi-randomised controlled trials comparing antipsychotic combinations with antipsychotic monotherapy for the treatment of schizophrenia and/or schizophrenia-like psychoses.

DATA COLLECTION AND ANALYSIS

We independently extracted data from the included studies. We analysed dichotomous data using risk ratios (RR) and the 95% confidence intervals (CI). We analysed continuous data using mean difference (MD) with a 95% CIs. For the meta-analysis we used a random-effects model. We used GRADE to complete a 'Summary of findings' table and assessed risk of bias for included studies.

MAIN RESULTS

Sixty-two studies are included in the review, 31 of these compared clozapine monotherapy with clozapine combination. We considered the risk of bias in the included studies to be moderate to high. The majority of trials had unclear allocation concealment, method of randomisation and blinding, and were not free of selective reporting.There is some limited evidence that combination therapy is superior to monotherapy in improving clinical response (RR 0.73, 95% CI 0.63 to 0.85; participants = 2364; studies = 29, very low-quality evidence), although subgroup analyses show that the positive result was due to the studies with clozapine in both the monotherapy and combination groups (RR 0.66, 95% CI 0.53 to 0.83; participants = 1127; studies = 17). Few studies reported on rate of relapse, most likely due to the short length of the studies. Overall, a combination of antipsychotics was not superior or inferior to antipsychotic monotherapy in preventing relapse (RR 0.63, 95% CI 0.31 to 1.29; participants = 512; studies = 3, very low-quality evidence), but the pooled data showed high heterogeneity (I² = 82%). A combination of antipsychotics was not superior or inferior to antipsychotic monotherapy in reducing the number of participants discontinuing treatment early (RR 0.89, 95% CI 0.73 to 1.07; participants = 3103; studies = 43, low-quality evidence). No difference was found between treatment groups in the number of participants hospitalised (RR 0.96, 95% CI 0.36 to 2.55; participants = 202; studies = 3, low-quality evidence) . We did not find evidence of a difference between treatment groups in serious adverse events or those requiring discontinuation (RR 1.05, 95% CI 0.65 to 1.69; participants = 2398; studies = 30, very low-quality evidence). There is as lack of evidence on clinically important change in quality of life, with only four studies reporting average endpoint or change data for this outcome on three different scales, none of which showed a difference between treatment groups.

AUTHORS' CONCLUSIONS

Currently, most evidence regarding the use of antipsychotic combinations comes from short-term trials, limiting the assessment of long-term efficacy and safety. We found very low-quality evidence that a combination of antipsychotics may improve the clinical response. We also found low-quality evidence that a combination of antipsychotics is may make no difference at preventing participants from leaving the study early, preventing relapse and/or causing more serious adverse events than monotherapy.

Clozapine as the most efficacious antipsychotic for activating ERK 1/2 kinases: Role of 5-HT2A receptor agonism

Antipsychotics (APDs) are divided into first-generation antipsychotics (FGAs) and second-generation antipsychotics (SGAs) based on the concept that SGAs have reduced motor side effects. With this premise, this study examined in HeLa and other cell lines the effects of different APDs on the activation of ERK1/2 (Extracellular signal-regulated kinases) and AKT (Protein Kinase B) kinases, which may be affected in schizophrenia and bipolar disorder. Among the SGAs, Clozapine clearly resulted as the most effective drug inducing ERK1/2 phosphorylation with potency in the low micromolar range. Quetiapine and Olanzapine showed a maximal response of about 50% compared to Clozapine, while FGAs such as Haloperidol and Sulpiride did not have any relevant effect. Among FGAs, Chlorpromazine was able to partially activate ERK1/2 at 30% compared to Clozapine. Referring to AKT activation, Clozapine, Quetiapine and Olanzapine demonstrated a similar efficacy, while FGAs, besides Chlorpromazine, were incapable to obtain any particular biological response. In relation to ERK1/2 activation, we found that 5-HT_2A serotonin receptor antagonists Ketanserin and M100907, both partially reduced Clozapine effect. In addition, we also observed an increase of potency of Clozapine effect in HeLa transfected cells with recombinant 5-HT_2A receptor and in rat glioma C6 cells that express a higher amount of this receptor. This indicates that ERK1/2 stimulation induced by Clozapine could, to some extent, be mediated by 5-HT_2A receptor, through a novel mechanism that is called "biased agonism", even though other cellular targets are involved. This evidence may be relevant to explain the superiority of Clozapine among the APDs.

Therapeutic Potential of Selectively Targeting the α2C-Adrenoceptor in Cognition, Depression, and Schizophrenia-New Developments and Future Perspective

α_2A- and α_2C-adrenoceptors (ARs) are the primary α₂-AR subtypes involved in central nervous system (CNS) function. These receptors are implicated in the pathophysiology of psychiatric illness, particularly those associated with affective, psychotic, and cognitive symptoms. Indeed, non-selective α₂-AR blockade is proposed to contribute toward antidepressant (e.g., mirtazapine) and atypical antipsychotic (e.g., clozapine) drug action. Both α_2C- and α_2A-AR share autoreceptor functions to exert negative feedback control on noradrenaline (NA) release, with α_2C-AR heteroreceptors regulating non-noradrenergic transmission (e.g., serotonin, dopamine). While the α_2A-AR is widely distributed throughout the CNS, α_2C-AR expression is more restricted, suggesting the possibility of significant differences in how these two receptor subtypes modulate regional neurotransmission. However, the α_2C-AR plays a more prominent role during states of low endogenous NA activity, while the α_2A-AR is relatively more engaged during states of high noradrenergic tone. Although augmentation of conventional antidepressant and antipsychotic therapy with non-selective α₂-AR antagonists may improve therapeutic outcome, animal studies report distinct yet often opposing roles for the α_2A- and α_2C-ARs on behavioral markers of mood and cognition, implying that non-selective α₂-AR antagonism may compromise therapeutic utility both in terms of efficacy and side-effect liability. Recently, several highly selective α_2C-AR antagonists have been identified that have allowed deeper investigation into the function and utility of the α_2C-AR. ORM-13070 is a useful positron emission tomography ligand, ORM-10921 has demonstrated antipsychotic, antidepressant, and pro-cognitive actions in animals, while ORM-12741 is in clinical development for the treatment of cognitive dysfunction and neuropsychiatric symptoms in Alzheimer's disease. This review will emphasize the importance and relevance of the α_2C-AR as a neuropsychiatric drug target in major depression, schizophrenia, and associated cognitive deficits. In addition, we will present new prospects and future directions of investigation.

Switching antipsychotics: Imaging the differential effect on the topography of postsynaptic density transcripts in antipsychotic-naïve vs. antipsychotic-exposed rats

The postsynaptic density (PSD) has been regarded as a functional switchboard at the crossroads of a dopamine-glutamate interaction, and it is putatively involved in the pathophysiology of psychosis. Indeed, it has been demonstrated that antipsychotics may modulate several PSD transcripts, such as PSD-95, Shank, and Homer. Despite switching antipsychotics is a frequent strategy to counteract lack of efficacy and/or side effect onset in clinical practice, no information is available on the effects of sequential treatments with different antipsychotics on PSD molecules. The aim of this study was to evaluate whether a previous exposure to a typical antipsychotic and a switch to an atypical one may affect the expression of PSD transcripts, in order to evaluate potential neurobiological correlates of this common clinical practice, with specific regards to putative synaptic plasticity processes. We treated male Sprague-Dawley rats intraperitoneally for 15days with haloperidol or vehicle, then from the sixteenth day we switched the animals to amisulpride or continued to treat them with vehicle or haloperidol for 15 additional days. In this way we got six first treatment/second treatment groups: vehicle/vehicle, vehicle/haloperidol, vehicle/amisulpride, haloperidol/vehicle, haloperidol/haloperidol, haloperidol/amisulpride. In this paradigm, we evaluated the expression of brain transcripts belonging to relevant and interacting PSD proteins, both of the Immediate-Early Gene (Homer1a, Arc) and the constitutive classes (Homer1b/c and PSD-95). The major finding was the differential effect of amisulpride on gene transcripts when administered in naïve vs. antipsychotic-pretreated rats, with modifications of the ratio between Homer1a/Homer1b transcripts and differential effects in cortex and striatum. These results suggest that the neurobiological effects on PSD transcripts of amisulpride, and possibly of other antipsychotics, may be greatly affected by prior antipsychotic treatments and may impact significantly on the switching procedure.

Risperidone-induced extrapyramidal side effects: is the need for anticholinergics the consequence of high plasma concentrations?

Antipsychotic drugs can induce various undesirable adverse motor reactions, such as extrapyramidal side effects (EPS). A widely accepted pharmacodynamic mechanism underlying EPS includes an increase in striatal D2-receptor occupancy. However, less is known about the pharmacokinetic background of EPS. The aim of this study was to analyze in-vivo possible pharmacokinetic patterns underlying biperiden-treated EPS in risperidone (RIS)-medicated patients. A large therapeutic drug monitoring database containing plasma concentrations of RIS and its metabolite 9-hydroxyrisperidone (9-OH-RIS) of 2293 adult inpatients and outpatients was analyzed. Two groups were compared: a group receiving RIS (n=772) and a group comedicated with biperiden (n=68). Plasma concentrations, dose-adjusted plasma concentrations (C/D) of RIS, 9-OH-RIS, and active moiety (AM) (RIS+9-OH-RIS) as well as ratios of concentrations for metabolite to parent drug (9-OH-RIS/RIS) were computed. We compared the plasma concentrations of the different compounds between the two groups considering the prescription of biperiden as an indirect report of EPS. The daily dosage of RIS did not differ between groups. No differences were detected in case of plasma concentrations and C/D of RIS and active metabolite between the groups. However, plasma concentrations of the AM were significantly higher in the comedicated group (P=0.032) and showed a trend in terms of the active metabolite 9-OH-RIS (P=0.053). Data indicate enhanced AM plasma concentrations of RIS in patients comedicated with biperiden as an EPS treatment. This might underscore an association between higher plasma concentrations of the AM and treatment-requiring EPS.

Effects of first-generation antipsychotics versus second-generation antipsychotics on quality of life in schizophrenia: a double-blind, randomised study

BACKGROUND

Whether or not second-generation antipsychotics (SGAs) represent an advantage over first-generation antipsychotics (FGAs) in the treatment of schizophrenia is not certain. Effectiveness studies published in the past 10 years have not unequivocally confirmed the superiority of SGAs over FGAs. We aimed to compare quality of life in patients with schizophrenia on an FGA strategy with those on an SGA strategy.

METHODS

In the multicentre, randomised, double-blind Neuroleptic Strategy Study (NeSSy), we recruited participants (aged 18-65 years) with schizophrenia (ICD-10: F20.X) who required treatment initiation or a change in treatment, from 14 psychiatric university hospitals and state hospitals in Germany. Double randomisation allowed for restricted selection of a treatment within each antipsychotic drug group (FGA or SGA) for an individual patient: first, patients were assigned with a random number table to two of six possible drug pairs, each pair consisting of an FGA (haloperidol [3-6 mg] or flupentixol [6-12 mg]) given orally and an SGA (aripiprazole [10-20 mg], olanzapine [10-20 mg], or quetiapine [400-800 mg]) given orally, and the investigator then selected which pair was best suited to the patient; a second, double-blind random assignment allocated either the FGA or the SGA from the investigator-chosen pair to the patient. Treatment duration was 24 weeks. Primary outcomes were change from baseline to week 24 in quality of life (SF-36) and clinical global impression (CGI-I), analysed in all randomly assigned patients who received at least one dose of the study drug. Safety was assessed in a safety set, consisting of all randomly assigned patients who received at least one dose of the study drug, coinciding with the set of the efficacy analyses. The study is registered with ClinicalTrials.gov, number NCT01164059; German Clinical Trials Register, number DRKS00000304; WHO ICTRP, number U1111-1112-9727; and EudraCT, number 2009-010966-47.

FINDINGS

Between April 1, 2010, and May 31, 2013, 149 patients were randomly assigned, 69 to FGA treatment and 80 to SGA treatment. 136 patients received at least one dose of study drug (63 in the FGA group, 73 in the SGA group). Mean area under the curve (AUC) values of SF-36 were significantly higher in the SGA group than in the FGA group (85·1 [SD 14·7] vs 79·7 [17·3], p=0·0112). Mean AUC values for CGI-I scores decreased in both groups, but were not significantly different between the two groups (3·39 [SD 0·89] in the FGA group vs 3·26 [0·92] in the SGA group, p=0·3423). 30 (48%) of 63 patients given FGAs had at least one adverse event compared with 42 (57%) of 73 patients given an SGA (p=0·3019); the most common were nervous system disorders (18 [60%] of 30 in the FGA group vs 19 [45%] of 42 in the SGA group) and psychiatric disorders (ten [33%] vs 16 [38%]). One patient died after cessation of study drug (olanzapine), most likely as a result of an illicit drug overdose. The increase in body-mass index (BMI) was significantly higher in the SGA group than in the FGA group (p=0·0021 at week 6 and p=0·0041 at week 24).

INTERPRETATION

Improvement of patient-reported quality of life was significantly higher in patients with schizophrenia given SGAs than in those given FGAs, when treatment selection was individualised. This advantage, however, has to be weighed against the potential metabolic adverse effects of some SGAs.

FUNDING

German Federal Ministry of Education and Research.

Polypharmacology of dopamine receptor ligands

Most neurological diseases have a multifactorial nature and the number of molecular mechanisms discovered as underpinning these diseases is continuously evolving. The old concept of developing selective agents for a single target does not fit with the medical need of most neurological diseases. The development of designed multiple ligands holds great promises and appears as the next step in drug development for the treatment of these multifactorial diseases. Dopamine and its five receptor subtypes are intimately involved in numerous neurological disorders. Dopamine receptor ligands display a high degree of cross interactions with many other targets including G-protein coupled receptors, transporters, enzymes and ion channels. For brain disorders like Parkinsońs disease, schizophrenia and depression the dopaminergic system, being intertwined with many other signaling systems, plays a key role in pathogenesis and therapy. The concept of designed multiple ligands and polypharmacology, which perfectly meets the therapeutic needs for these brain disorders, is herein discussed as a general ligand-based concept while focusing on dopaminergic agents and receptor subtypes in particular.

Pharmacogenetics and outcome with antipsychotic drugs

Antipsychotic medications are the gold-standard treatment for schizophrenia, and are often prescribed for other mental conditions. However, the efficacy and side-effect profiles of these drugs are heterogeneous, with large interindividual variability. As a result, treatment selection remains a largely trial-and-error process, with many failed treatment regimens endured before finding a tolerable balance between symptom management and side effects. Much of the interindividual variability in response and side effects is due to genetic factors (heritability, h²~ 0.60-0.80). Pharmacogenetics is an emerging field that holds the potential to facilitate the selection of the best medication for a particular patient, based on his or her genetic information. In this review we discuss the most promising genetic markers of antipsychotic treatment outcomes, and present current translational research efforts that aim to bring these pharmacogenetic findings to the clinic in the near future.

Subtyping Schizophrenia by Treatment Response: Antipsychotic Development and the Central Role of Positive Symptoms

We have recently proposed a model for subtyping schizophrenia based on antipsychotic (AP) treatment response. Evidence suggests that APs, both old and new, are comparable in terms of efficacy; however, one AP, clozapine, is uniquely effective in one subgroup of patients (that is, those with treatment-resistant schizophrenia [TRS]). This permits us to subdivide schizophrenia into 3 specific groups: AP responsive, clozapine responsive, and clozapine resistant. Here, we integrate this model with current criteria related to TRS and ultraresistant schizophrenia, the latter referred to in our model as clozapine resistant. We suggest several modifications to existing criteria, in line with current evidence and practice patterns, particularly emphasizing the need to focus on positive symptoms. While APs can favourably impact numerous dimensions related to schizophrenia, it is their effect on positive symptoms that distinguishes them from other psychotropics. Further, it is positive symptoms that are central to AP and clozapine resistance, and it is these people that place the greatest demands on acute and long-term inpatient resources. In moving AP development forward, we advocate specifically focusing on positive symptoms and capitalizing on the evidence we have of 3 subtypes of psychosis (that is, positive symptoms) based on treatment response, implicating 3 distinguishable forms of underlying pathophysiology. Conversely, pooling these groups risks obfuscating potentially identifiable differences. Such a position does not challenge the importance of dopamine D2 receptor blockade, but rather highlights the need to better isolate those other subgroups that require something more or entirely different.

Second-generation antipsychotics and neuroleptic malignant syndrome: systematic review and case report analysis

BACKGROUND

Neuroleptic malignant syndrome (NMS) is a rare, severe, idiosyncratic adverse reaction to antipsychotics. Second-generation antipsychotics (SGAs) were originally assumed to be free from the risk of causing NMS, however several cases of NMS induced by SGAs (SGA-NMS) have been reported.

OBJECTIVES

The aim of this study was to systematically review available studies and case reports on SGA-NMS and compare the presentation of NMS induced by different SGAs.

DATA SOURCES

Citations were retrieved from PubMed up to November 2013, and from reference lists of relevant citations.

STUDY ELIGIBILITY CRITERIA

Eligibility criteria included (a) primary studies reporting data on NMS, with at least 50 % of the sample receiving SGAs; or (b) case reports and case reviews reporting on NMS induced by SGA monotherapy, excluding those due to antipsychotic withdrawal.

STUDY APPRAISAL AND SYNTHESIS METHODS

A standardized method for data extraction and coding was developed for the analysis of eligible case reports.

RESULTS

Six primary studies and 186 individual cases of NMS induced by SGAs were included. Primary studies suggest that SGA-NMS is characterized by lower incidence, lower clinical severity, and less frequent lethal outcome than NMS induced by first-generation antipsychotics. Systematic analysis of case reports suggests that even the most recently marketed antipsychotics are not free from the risk of inducing NMS. Furthermore, clozapine-, aripiprazole- and amisulpride-induced NMS can present with atypical features more frequently than other SGA-NMS, i.e. displaying less intense extrapyramidal symptoms or high fever.

LIMITATIONS

Case reports report non-systematic data, therefore analyses may be subject to bias.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

Clinicians should be aware that NMS is virtually associated with all antipsychotics, including those most recently marketed. Although apparently less severe than NMS induced by older antipsychotics, SGA-NMS still represent a relevant clinical issue.

Aripiprazole: from pharmacological profile to clinical use

Clinical experience with aripiprazole has confirmed the effectiveness and the safety of this novel antipsychotic drug in patients with schizophrenia as well as for the treatment of mania in type I bipolar disorder. However the generalization of the results from clinical trials requires further effort in order to address some issues and to overcome incorrect and partial interpretation of the clinical evidence. This article provides some straightforward guidance that may help clinical psychiatrists to translate the mechanism of action of aripiprazole into clinical setting, thus improving the appropriate use of the drug through rational application of its pharmacological profile. Examples of paradigmatic clinical situations are presented and discussed, suggesting possible intervention strategies, which may contribute to achieving the most appropriate use of the pharmacological properties of aripiprazole in real life settings.

COMT Val158Met and 5-HT1A-R -1019 C/G polymorphisms: effects on the negative symptom response to clozapine

Aim: Clozapine is still considered the gold standard for treatment-resistant schizophrenia patients; however, up to 40% of patients do not respond adequately. Identifying potential predictors of clinical response to this last-line antipsychotic could represent an important goal for treatment. Among these, functional polymorphisms involved in dopamine system modulation, known to be disrupted in schizophrenia, may play a role. We examined the COMT Val158Met polymorphism, which plays a key role in dopamine regulation at the prefrontal level, and the 5-HT1A-R -1019 C/G polymorphism, a target of clozapine activity involved in the interaction between the serotonin and dopamine systems. Materials & methods: 107 neuroleptic-refractory, biologically unrelated Italian patients (70 males and 37 females) with a DSM-IV diagnosis of schizophrenia who were being treated with clozapine were recruited. Psychopathology was assessed by the Positive and Negative Symptoms Scale (PANSS) at the beginning of treatment, and at weeks 8 and 12. Genomic DNA was extracted from venous blood samples. COMT rs4680 (Val158Met) and 5-HT1A-R rs6295 (-1019 C/G) polymorphisms were analyzed by PCR-based restriction fragment length and direct sequencing, respectively. Results: We found a significant effect of COMT and 5-HT1A-R on the PANSS Negative Subscale variation, with greater improvement among COMT Val/Val and 5-HT1A-R G/G subjects. Conclusion: The findings support the hypothesis that COMT rs4680 and 5-HT1A-R rs6295 polymorphisms could influence the negative symptom response to clozapine, probably through modulation of the dopaminergic system.

Original submitted 26 February 2014; Revision submitted 15 October 2014

Formulation and characterization of clozapine and risperidone co-entrapped spray-dried PLGA nanoparticles

In the current study, polylactide-co-glycolide (PLGA) nanoparticles entrapping both clozapine (CLZ) and risperidone (RIS) were formulated by spray-drying using Buchi Nano Spray Dryer B-90 (Flawil, Switzerland). Parameters such as inlet temperature, spray mesh diameter, sample flow rate, spray rate and applied pressure were optimized to produce nanoparticles having desired release profile using both low- and high-molecular weight PLGA polymer. Smallest size nanoparticle of size around 248 nm could be prepared using a 4.0 μm mesh diameter with low-molecular weight polymer. The load of CLZ and RIS was 126.3 and 58.2 μg/mg of polymer particles, respectively. Entrapment efficiency of drugs in PLGA nanoparticles was 94.74% for CLZ and 93.12% for RIS. Both the drugs released continuously from the nanoparticle formulations. PLGA nanoparticles formulated using low-molecular weight polymer released around 80% of the entrapped drug over 10 days of time. Nature of drug inside polymer particles was amorphous, and there was no chemical interaction of CLZ and RIS with polymer. Polymeric nanoparticles were found to be non-toxic in nature using PC12 cell line. This nanospray drying process proved to be suitable for developing polymeric nanoformulation delivering dual drugs for the treatment of Schizophrenia.

Perinatal use of aripiprazole: plasma levels, placental transfer, and child outcome in 3 new cases

The use of new agents of second-generation antipsychotics in childbearing women is increasing and poses an unknown risk to the fetus; thus, information of pregnancy and child outcome are urgently needed. We reviewed the literature of 12 patients, 3 of them were exposed during the first trimester, and added 3 new cases of peripartum use of aripiprazole. No teratogenesis was observed despite all 3 women having received the substance during part or full first trimester. All 3 pregnancies were uncomplicated with spontaneous birth. Dosage had to be changed during the course of gestation from 2.5 to 15 mg and plasma levels (PL) were below recommended levels, although all 3 women remained in stable remission throughout pregnancy and postpartum period.The extent of placental transfer of aripiprazole (mean ratio of 56.2%) is comparable with that of other second-generation antipsychotics.Our observations have clinical implications: antipsychotic PLs show large-scale decreases, which may require dose adjustments during pregnancy. Pregnant women may require lower PLs. In our cases, a PL of one third of the previous effective PL was effective and safe. Repeated therapeutic drug monitoring during late gestation based on individual, previous effective PLs seems to be a feasible way for safe and effective antipsychotic therapy in unplanned pregnancy.

How antipsychotics impact the different dimensions of Schizophrenia: a test of competing hypotheses

The clinical expression of schizophrenia is generally reported to be expressed by three to five different factors (i.e. positive, negative, disorganization, excitability, anxiety-depression symptoms). It is often claimed that antipsychotic medications are particularly helpful for positive symptoms, but not for the others, suggesting a differential efficacy for different aspects of the disorder. We formally tested this claim. Using Structural Equation Modeling in two large [1884 patients] clinical trials in schizophrenia, we compared the model of a common general effect of antipsychotics to models whereby the antipsychotics have multiple and differential effects on the different factors of the illness. We validated the generalizability of the model in further trials involving antipsychotics in chronic [1460 patients] and first-episode patients [1053 patients]. Across different populations, different trials and different antipsychotics - the best-fitting model suggests that symptom response in schizophrenia is underpinned by a single general effect with secondary and minor lower-order effects on specific symptom domains. This single-factor model explained nearly 80% of the variance, was superior to the assumption of unique efficacy for specific domains; and replicated across antipsychotics and illness stages. Despite theoretical and pharmacological claims the differential efficacy of antipsychotics on the various dimensions of schizophrenia is not supported in the prevailing data. The implication of this finding for the measurement of treatment response and our understanding of the neurobiology of antipsychotic action, for clinical practice and for future drug development are discussed.

Drug elucidation: invertebrate genetics sheds new light on the molecular targets of CNS drugs

Many important drugs approved to treat common human diseases were discovered by serendipity, without a firm understanding of their modes of action. As a result, the side effects and interactions of these medications are often unpredictable, and there is limited guidance for improving the design of next-generation drugs. Here, we review the innovative use of simple model organisms, especially Caenorhabditis elegans, to gain fresh insights into the complex biological effects of approved CNS medications. Whereas drug discovery involves the identification of new drug targets and lead compounds/biologics, and drug development spans preclinical testing to FDA approval, drug elucidation refers to the process of understanding the mechanisms of action of marketed drugs by studying their novel effects in model organisms. Drug elucidation studies have revealed new pathways affected by antipsychotic drugs, e.g., the insulin signaling pathway, a trace amine receptor and a nicotinic acetylcholine receptor. Similarly, novel targets of antidepressant drugs and lithium have been identified in C. elegans, including lipid-binding/transport proteins and the SGK-1 signaling pathway, respectively. Elucidation of the mode of action of anesthetic agents has shown that anesthesia can involve mitochondrial targets, leak currents, and gap junctions. The general approach reviewed in this article has advanced our knowledge about important drugs for CNS disorders and can guide future drug discovery efforts.

Cariprazine, a new, orally active dopamine D2/3 receptor partial agonist for the treatment of schizophrenia, bipolar mania and depression

Cariprazine is a novel drug with partial agonist activity at dopamine D2/3 receptors and six- to eightfold higher affinity for human dopamine D3 over D2 receptors. Results from several placebo-controlled Phase II/III trials in patients with a The Diagnostic and Statistical Manual of Mental Disorders IV diagnosis of schizophrenia or bipolar I disorder suggest that cariprazine is superior to placebo with respect to antipsychotic and antimanic activity. Reports concerning safety and tolerability of cariprazine are mainly favorable, although the rates of treatment-associated adverse events, which most commonly included akathisia and extrapyramidal symptom, are rather high. However, only minor alterations of clinical laboratory values, prolactin concentrations and ECG parameters are reported in cariprazine-treated patients. A new drug application to the U.S. F DA for cariprazine for the treatment of both schizophrenia and manic or mixed episodes associated with bipolar I disorder was submitted in November 2012. A more precise assessment of the clinical properties of this new drug will require additional studies, aimed to compare and contrast cariprazine with other antipsychotic agents.

Pharmacogenetics of antipsychotic treatment in schizophrenia

Antipsychotics are the mainstay treatment for schizophrenia. There is large variability between individuals in their response to antipsychotics, both in efficacy and adverse effects of treatment. While the source of interindividual variability in antipsychotic response is not completely understood, genetics is a major contributing factor. The identification of pharmacogenetic markers that predict antipsychotic efficacy and adverse reactions is a growing area of research, and holds the potential to replace the current trial-and-error approach to treatment selection in schizophrenia with a personalized medicine approach.In this chapter, we provide an overview of the current state of pharmacogenetics in schizophrenia treatment. The most promising pharmacogenetic findings are presented for both antipsychotic response and commonly studied adverse reactions. The application of pharmacogenetics to schizophrenia treatment is discussed, with an emphasis on the clinical utility of pharmacogenetic testing and directions for future research.

Imaging brain gene expression profiles by antipsychotics: region-specific action of amisulpride on postsynaptic density transcripts compared to haloperidol

Induction of motor disorders is considered the clinical landmark differentiating typical from atypical antipsychotics, and has been mainly correlated to dopamine D2 receptors blockade in striatum. This view is challenged by benzamides, such as amisulpride, which display low liability for motor side effects despite being D2/D3 receptors high-affinity blocking agents. These effects have been explained with the prominent presynaptic action of amisulpride or with the fast dissociation at D2 receptors, but there is scarce information on the effects of amisulpride on postsynaptic signaling. We carried out a molecular imaging study of gene expression after acute administration of haloperidol (0.8 mg/kg), amisulpride (10 or 35 mg/kg), or vehicle, focusing on postsynaptic genes that are key regulators of synaptic plasticity, such as Arc, c-fos, Zif-268, Norbin, Homer. The last one has been associated to schizophrenia both in clinical and preclinical studies, and is differentially induced by antipsychotics with different D2 receptors affinity. Topography of gene expression revealed that amisulpride, unlike haloperidol, triggers transcripts expression peak in medial striatal regions. Correlation analysis of gene expression revealed a prevalent correlated gene induction within motor corticostriatal regions by haloperidol and a more balanced gene induction within limbic and motor corticostriatal regions by amisulpride. Despite the selective dopaminergic profile of both compounds, our results demonstrated a differential modulation of postsynaptic molecules by amisulpride and haloperidol, the former impacting preferentially medial regions of striatum whereas the latter inducing strong gene expression in lateral regions. Thus, we provided a possible molecular profile of amisulpride, putatively explaining its "atypical atypicality".

Differential responses to JNJ-37822681, a specific and fast dissociating dopamine D2 receptor antagonist, in cynomolgus monkey and Sprague-Dawley rat general toxicology studies: clinical observations, prolactin levels, mammary histopathology findings and toxicokinetics

JNJ-37822681 is a potent, specific and fast dissociating dopamine D2 receptor antagonist intended for the treatment of schizophrenia. Its nonclinical toxicological profile was investigated in a series of general repeat dose toxicity studies in cynomolgus monkeys and Sprague-Dawley rats. The maximum duration of treatment was 9 and 6 months, respectively. Interspecies differences were noted in the response to JNJ-37822681 in terms of extrapyramidal (EPS)-like clinical signs and prolactin-mediated tissue changes in the mammary gland. Monkeys showed severe EPS-like clinical signs such as abnormal posture, abnormal eye movements and hallucination-like behavior at relatively low exposures compared to those associated with EPS in patients with schizophrenia. The high sensitivity of the monkey to JNJ-37822681-induced EPS-like signs was unexpected based on the fast dissociating properties of the compound. Rats, however, were not prone to EPS. Elevated serum prolactin levels were found in rats and monkeys. While rats showed slight to moderate prolactin-related tissue changes upon histopathological examination in all studies, which among others affected the mammary gland, only minor mammary gland tissue changes were noted in monkeys. Prolactin levels were only slightly increased in patients with schizophrenia receiving relatively high dose levels of JNJ-37822681. The monkey toxicology studies did not provide an exposure-based safety margin, while in rats adverse effects were only noted at exposures considerably higher than those achieved at efficacious plasma concentrations in the clinic. Overall, the available data suggest that the cynomolgus monkey showed better predictivity towards the nature of JNJ-37822681-associated adverse events in humans than the Sprague-Dawley rat.