Mechanisms of action of atypical antipsychotic drugs: a critical analysis

How to classify antipsychotics: time to ditch dichotomies?

The dichotomies of 'typical/atypical' or 'first/second generation' have been employed for several decades to classify antipsychotics, but justification for their use is not clear. In the current analysis we argue that this classification is flawed from both clinical and pharmacological perspectives. We then consider what approach should ideally be employed in both clinical and research settings.

Physicochemical Insights on Terahertz Wave Diminished Side Effects of Drugs from Slow Dissociation

Dopamine D2 receptors (D2Rs) are one of the most intensely investigated and well-established drug targets for neuropsychiatric disorders. Selective D2R antagonists have been developed as efficacious antipsychotic drugs. Nevertheless, the potent drugs with necessarily high affinity are prone to slow dissociation, which invokes a plethora of severe side effects such as extrapyramidal symptoms, substantial weight gain, associated diabetes, etc. This has become a major barrier in treating psychiatric patients. In this work, we propose a physical method, terahertz wave modulation, to promote the dissociation of high-affinity antipsychotics and thus diminish the side effects. We have proven that a 4.0 THz wave could reduce the affinity by 71% between the D2R and a risperidone ligand and meanwhile expand the exit via conformation modulation, which promises an accelerated dissociation of risperidone. In addition, it is estimated that the enhancement of the dissociation rate due to lowered binding by terahertz irritation could constitute up to 8 orders of magnitude, which is fairly impressive and resembles the enzyme's catalysis. Also, acceleration of the dissociation rate could be adjusted by the irritation strength. This work elaborates the terahertz wave-modulated noncovalent interactions critical in cell signaling pathways. Most importantly, it demonstrates the feasibility of terahertz technologies intervening in receptor-ligand complex regulated diseases such as neurodegenerative disorders, metabolic diseases, etc.

Consequences of Antipsychotic Medications on Mental Health

Individuals suffering from mental illnesses, unfortunately, have a shorter lifespan. The increase in mortality rates is primarily due to physical illness, unhealthy lifestyle, and associated comorbidities. Antipsychotic medications, previously known as tranquilizers, antipsychotics, or neuroleptics, can alleviate or attenuate symptoms related to psychosis, delusion, and/or hallucinations and are used in the treatment of psychosis, schizophrenia, bipolar disorder, depression, or Alzheimer's disease. Within hours to days, these medications cause calm and reduce confusion in individuals with psychosis however may take longer for full effect. Importantly, these drugs are not curing, but only treat the disease symptoms. The treatment is adjusted to reduce any psychotic symptoms while keeping the adverse effects to a minimum level. Antipsychotics may lead to increased risk of diseases, including but not limited to, diabetes, obesity, metabolic disorders, cardiovascular, renal, or respiratory disorders. Improved dosages, polypharmacy, and age-specific treatment play an important role in limiting the comorbidities as well as the side effects. Further research and clinical attention are required to understand the functioning of these medications. The review focuses on the use of antipsychotic medications in different diseases and their effect on mental health.

Atypical antipsychotic drugs deregulate the cholesterol metabolism of macrophage-foam cells by activating NOX-ROS-PPARγ-CD36 signaling pathway

BACKGROUND

Clinical reports indicate that schizophrenia patients taking atypical antipsychotic drugs suffer from metabolism diseases including atherosclerosis. However, the mechanisms underlying the detrimental effect of atypical antipsychotic drugs on atherosclerosis remain to be explored.

METHODS

In this study, we used apolipoprotein E-deficient (apoe^-/-) hyperlipidemic mice and apoe^-/-cd36^-/- mice to investigate the underlying mechanism of atypical antipsychotic drugs on atherosclerosis and macrophage-foam cells.

RESULTS

In vivo studies showed that genetic deletion of cd36 gene ablated the pro-atherogenic effect of olanzapine in apoe^-/- mice. Moreover, in vitro studies revealed that genetic deletion or siRNA-mediated knockdown of cd36 or pharmacological inhibition of CD36 prevented atypical antipsychotic drugs-induced oxLDL accumulation in macrophages. Additionally, olanzapine and clozapine activated NADPH oxidase (NOX) to generate reactive oxygen species (ROS) which upregulated the activity of peroxisome proliferator-activated receptor γ (PPARγ) and subsequently elevated CD36 expression. Inhibition of NOX activity, ROS production or PPARγ activity suppressed CD36 expression and abolished the detrimental effects of olanzapine and clozapine on oxLDL accumulation in macrophages.

CONCLUSION

Collectively, our results suggest that atypical antipsychotic drugs exacerbate atherosclerosis and macrophage-foam cell formation by activating the NOX-ROS-PPARγ-CD36 pathway.

Long-term effect on outcome of clozapine in chronic therapy-resistant schizophrenic patients

Controlled clinical trials have shown that the atypical neuroleptic clozapine is highly effective in schizophrenic patients who are unresponsive to conventional neuroleptic agents. The long-term outcome of clozapine treatment was studied in 122 patients who were treated between 1974 and 1991. The mean duration of treatment was 5.2 years. At follow-up, 74 patients (61%) were still receiving clozapine. Only 11 patients discontinued treatment because of adverse events and eight because of poor compliance. Clinical improvement was seen in 87% of patients; 40% had resumed employment after 2 years' treatment. About one-third of patients who received clozapine for 5–10 years continued to improve during this time; this was probably because of a continuing process of socialisation. Thus, clozapine offers important advantages in schizophrenic patients resistant to conventional neuroleptics in terms of long-term efficacy and lack of extrapyramidal side-effects.

The Cross-Talk Between the Dopaminergic and the Immune System Involved in Schizophrenia

Dopamine is one of the neurotransmitters whose transmission is altered in a number of neural pathways in the brain of schizophrenic patients. Current evidence indicates that these alterations involve hyperactive dopaminergic transmission in mesolimbic areas, striatum, and hippocampus, whereas hypoactive dopaminergic transmission has been reported in the prefrontal cortex of schizophrenic patients. Consequently, schizophrenia is associated with several cognitive and behavioral alterations. Of note, the immune system has been found to collaborate with the central nervous system in a number of cognitive and behavioral functions, which are dysregulated in schizophrenia. Moreover, emerging evidence has associated schizophrenia and inflammation. Importantly, different lines of evidence have shown dopamine as a major regulator of inflammation. In this regard, dopamine might exert strong regulation in the activity, migration, differentiation, and proliferation of immune cells that have been shown to contribute to cognitive functions, including T-cells, microglial cells, and peripheral monocytes. Thereby, alterations in dopamine levels associated to schizophrenia might affect inflammatory response of immune cells and consequently some behavioral functions, including reference memory, learning, social behavior, and stress resilience. Altogether these findings support the involvement of an active cross-talk between the dopaminergic and immune systems in the physiopathology of schizophrenia. In this review we summarize, integrate, and discuss the current evidence indicating the involvement of an altered dopaminergic regulation of immunity in schizophrenia.

Molecular mechanisms of anti-psychotic drugs for improvement of cancer treatment

Anti-psychotic medications are widely used to treat schizophrenia and bipolar disorder. Besides their medical applications, anti-psychotic drugs have other pharmacological properties which are involved in multiple intracellular functions including metabolism, cell stress, cell-cycle regulation, survival and apoptosis through modulation of cellular signaling pathways such as PI3K/Akt/GSK-3β, STAT3 and wingless (Wnt)-related intracellular signaling. Also, anti-psychotics counteract the growth of tumor cells by stimulating the cellular immune system and natural killer cells. On the other hand, the positive charge and the lipophilicity of anti-psychotics have significant roles in the inhibition of P-gp pumps resulting in accumulation of chemotherapy drugs as well as increasing the cellular susceptibility to chemotherapy, autophagy, angiogenesis inhibition, stem cells differentiation induction and changing the expression of tumor suppressor genes and oncogenes. Overall, anti-psychotics are able to inhibit the proliferation of cancer cells through modulation of different cellular pathways. Anti-psychotics act as anti-cancer drugs and besides can increase the efficacy of anti-cancer agents in cancer cells. In this study, the anti-cancer effects of different anti-psychotic medicines on various malignant tumor cells and their molecular mechanisms have been discussed.

Schizophrenia, Dopamine and the Striatum: From Biology to Symptoms

The mesolimbic hypothesis has been a central dogma of schizophrenia for decades, positing that aberrant functioning of midbrain dopamine projections to limbic regions causes psychotic symptoms. Recently, however, advances in neuroimaging techniques have led to the unanticipated finding that dopaminergic dysfunction in schizophrenia is greatest within nigrostriatal pathways, implicating the dorsal striatum in the pathophysiology and calling into question the mesolimbic theory. At the same time our knowledge of striatal anatomy and function has progressed, suggesting new mechanisms via which striatal dysfunction may contribute to the symptoms of schizophrenia. This Review draws together these developments, to explore what they mean for our understanding of the pathophysiology, clinical manifestations, and treatment of the disorder.

Techniques for characterising the mesostriatal dopamine system, both in humans and animal models, have advanced significantly over the past decade.

In vivo imaging studies in schizophrenia patients demonstrate that dopaminergic dysfunction in schizophrenia is greatest in nigrostriatal as opposed to mesolimbic pathways.

Better understanding of striatal structure and function has enhanced our insight into the neurobiological basis of psychotic symptoms.

The role of other neurotransmitters in modulating striatal dopamine function merits further exploration, and modulating these neurotransmitter systems has potential to offer new therapeutic strategies.

Defining the Locus of Dopaminergic Dysfunction in Schizophrenia: A Meta-analysis and Test of the Mesolimbic Hypothesis

BACKGROUND

Studies using positron emission tomography to image striatal dopamine function, have demonstrated that individuals with schizophrenia display increases in presynaptic function. Mesolimbic dysfunction specifically, has previously been suggested to underlie psychotic symptoms. This has not been directly tested in vivo, and the precise anatomical locus of dopamine dysfunction within the striatum remains unclear. The current article investigates the magnitude of dopaminergic abnormalities in individuals with schizophrenia, and determines how the magnitude of abnormality varies across functional subdivisions of the striatum.

METHODS

EMBASE, PsychINFO, and MEDLINE were searched from January 1, 1960, to December 1, 2016. Inclusion criteria were molecular imaging studies that had measured presynaptic striatal dopamine functioning. Effects sizes for whole striatum and functional subdivisions were calculated separately. The magnitude of difference between functional subdivisions in patients and controls was meta-analyzed.

RESULTS

Twenty-one eligible studies were identified, including 269 patients and 313 controls. Individuals with schizophrenia (Hedges' g = 0.68, P < .001) demonstrated elevated presynaptic dopamine functioning compared to controls. Seven studies examined functional subdivisions. These demonstrated significant increases in patients compared to controls in associative (g = 0.73, P = .002) and sensorimotor (g = 0.54, P = .005) regions, but not limbic (g = 0.29, P = .09). The magnitude of the difference between associative and limbic subdivisions was significantly greater in patients compared to controls (g = 0.39, P = .003).

CONCLUSION

In individuals with schizophrenia dopaminergic dysfunction is greater in dorsal compared to limbic subdivisions of the striatum. This is inconsistent with the mesolimbic hypothesis and identifies the dorsal striatum as a target for novel treatment development.

Clozapine Intoxication Mimicking Acute Stroke

Clozapine is an atypical antipsychotic drug prescribed for treatment-resistant schizophrenia. The risk of adverse hematologic, cardiovascular, and neurologic effects has tempered its use, and reports of overdoses remain rare. We report a case of accidental acute clozapine intoxication in a clozapine-naïve patient, who presented with symptoms mimicking acute stroke and later developed status epilepticus. Clozapine intoxication is a rare presentation in the emergency department with potential for iatrogenic harm if not correctly identified.

Mining the Potential of Label-Free Biosensors for In Vitro Antipsychotic Drug Screening

The pharmaceutical industry is facing enormous challenges due to high drug attribution rates. For the past decades, novel methods have been developed for safety and efficacy testing, as well as for improving early development stages. In vitro screening methods for drug-receptor binding are considered to be good alternatives for decreasing costs in the identification of drug candidates. However, these methods require lengthy and troublesome labeling steps. Biosensors hold great promise due to the fact that label-free detection schemes can be designed in an easy and low-cost manner. In this paper, for the first time in the literature, we aimed to compare the potential of label-free optical and impedimetric electrochemical biosensors for the screening of antipsychotic drugs (APDs) based on their binding properties to dopamine receptors. Particularly, we have chosen a currently-used atypical antipsychotic drug (Buspirone) for investigating its dopamine D3 receptor (D3R) binding properties using an impedimetric biosensor and a nanoplasmonic biosensor. Both biosensors have been specifically functionalized and characterized for achieving a highly-sensitive and reliable analysis of drug-D3R binding. Our biosensor strategies allow for comparing different affinities against the D3R, which facilitates the identification of strong or weak dopamine antagonists via in vitro assays. This work demonstrates the unique potential of label-free biosensors for the implementation of cost-efficient and simpler analytical tools for the screening of antipsychotic drugs.

How CATIE brought us back to Kansas: a critical re-evaluation of the concept of atypical antipsychotics and their place in the treatment of schizophrenia

The subdivision of the class of antipsychotic drugs into two discrete groups – ‘conventional’ (or first generation) and ‘atypical’ (or second generation) – has been adopted as standard, with the latter generally accepted as ‘better’ and widely recommended as automatic first-line choices. However, this perception has been thrown into confusion with the results of large pragmatic trials that failed to identify advantages with the new, more expensive drugs, while identifying worrying tolerability issues. This article explores the origins of ‘atypicality’, its construction on the back of a confusing and weak clinical validator (diminished liability to promote parkinsonism) and how even in relation to the archetypical atypical, clozapine, the uncertain boundaries of drug-induced extrapyramidal dysfunction may be contributing to confusion about ‘efficacy’ and ‘tolerability’. It argues that abandoning atypicality would open up clinical practice to all drugs of a single class of ‘antipsychotics’ and allow for individualised risk/benefit appraisal as a basis for truly tailored treatment recommendations.

The development of antipsychotic drugs

Antipsychotic drugs revolutionised psychiatric practice and provided a range of tools for exploring brain function in health and disease. Their development and introduction were largely empirical but based on long and honourable scientific credentials and remarkable powers of clinical observation. The class shares a common core action of attenuating central dopamine transmission, which underlies the major limitation to their use - high liability to disrupt extrapyramidal function - and also the most durable hypothesis of the basis of psychotic disorders, especially schizophrenia. However, the Dopamine Hypothesis, which has driven drug development for almost half a century, has become a straight-jacket, stifling innovation, resulting in a class of compounds that are largely derivative. Recent efforts only cemented this tendency as no clinical evidence supports the notion that newer compounds, modelled on clozapine, share that drug's unique neurological tolerability and can be considered 'atypical'. Patients and doctors alike must await a more profound understanding of central dopamine homeostasis and novel methods of maintaining it before they can again experience the intoxicating promise antipsychotics once held.

Olanzapine: Psychopharmacology, Clinical Efficacy, and Adverse Effects

Olanzapine is an atypical antipsychotic that has a pharmacological profile similar that of clozapine. It is biotransformed by hepatic enzymes and can be dosed on a once-daily basis. In large, double-blind, placebo-controlled trials, olanzapine was shown to be efficacious in the treatment of schizophrenia relative to placebo. Many trials showed superior efficacy to haloperidol, especially against negative symptoms. Olanzapine is FDA-approved for the treatment of psychotic disorders, though data suggest possible use in depression, bipolar disorder, psychogenic polydipsia, and developmental disabilities. Olanzap-ine appears to be well-tolerated. Commonly reported adverse effects include orthostatic hypotension, sedation, hepatic transaminase elevations, weight gain, headache, agitation, dizziness, and constipation. The incidence of extrapyramidal symptoms and tardive dyskinesia is low. Few drug interactions have been reported. The recommended starting dose is 10 mg once daily. One trial indicated that the higher cost of this agent might be offset by a reduction in overall hospitalization costs.

Chlorpromazine versus atypical antipsychotic drugs for schizophrenia

BACKGROUND

Chlorpromazine is an aliphatic phenothiazine, which is one of the widely-used typical antipsychotic drugs. Chlorpromazine is reliable for its efficacy and one of the most tested first generation antipsychotic drugs. It has been used as a 'gold standard' to compare the efficacy of older and newer antipsychotic drugs. Expensive new generation drugs are heavily marketed worldwide as a better treatment for schizophrenia, but this may not be the case and an unnecessary drain on very limited resources.

OBJECTIVES

To compare the effects of chlorpromazine with atypical or second generation antipsychotic drugs, for the treatment of people with schizophrenia.

SEARCH METHODS

We searched the Cochrane Schizophrenia Group's Trials Register up to 23 September 2013.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared chlorpromazine with any other atypical antipsychotic drugs for treating people with schizophrenia. Adults (as defined in each trial) diagnosed with schizophrenia, including schizophreniform, schizoaffective and delusional disorders were included in this review.

DATA COLLECTION AND ANALYSIS

At least two review authors independently screened the articles identified in the literature search against the inclusion criteria and extracted data from included trials. For homogeneous dichotomous data, we calculated the risk ratio (RR) and the 95% confidence intervals (CIs). For continuous data, we determined the mean difference (MD) values and 95% CIs. We assessed the risk of bias in included studies and rated the quality of the evidence using the GRADE approach.

MAIN RESULTS

This review includes 71 studies comparing chlorpromazine to olanzapine, risperidone or quetiapine. None of the included trials reported any data on economic costs. 1. Chlorpromazine versus olanzapineIn the short term, there appeared to be a significantly greater clinical response (as defined in each study) in people receiving olanzapine (3 RCTs, N = 204; RR 2.34, 95% CI 1.37 to 3.99, low quality evidence). There was no difference between drugs for relapse (1 RCT, N = 70; RR 1.5, 95% CI 0.46 to 4.86, very low quality evidence), nor in average endpoint score using the Brief Psychiatric Rating Scale (BPRS) for mental state (4 RCTs, N = 245; MD 3.21, 95% CI -0.62 to 7.05,very low quality evidence). There were significantly more extrapyramidal symptoms experienced amongst people receiving chlorpromazine (2 RCTs, N = 298; RR 34.47, 95% CI 4.79 to 248.30,very low quality evidence). Quality of life ratings using the general quality of life interview (GQOLI) - physical health subscale were more favourable with people receiving olanzapine (1 RCT, N = 61; MD -10.10, 95% CI -13.93 to -6.27, very low quality evidence). There was no difference between groups for people leaving the studies early (3 RCTs, N = 139; RR 1.69, 95% CI 0.45 to 6.40, very low quality evidence). 2. Chlorpromazine versus risperidoneIn the short term, there appeared to be no difference in clinical response (as defined in each study) between chlorpromazine or risperidone (7 RCTs, N = 475; RR 0.84, 95% CI 0.53 to 1.34, low quality of evidence), nor in average endpoint score using the BPRS for mental state 4 RCTs, N = 247; MD 0.90, 95% CI -3.49 to 5.28, very low quality evidence), or any observed extrapyramidal adverse effects (3 RCTs, N = 235; RR 1.7, 95% CI 0.85 to 3.40,very low quality evidence). Quality of life ratings using the QOL scale were significantly more favourable with people receiving risperidone (1 RCT, N = 100; MD -14.2, 95% CI -20.50 to -7.90, very low quality evidence). There was no difference between groups for people leaving the studies early (one RCT, N = 41; RR 0.21, 95% CI 0.01 to 4.11, very low quality evidence). 3. Chlorpromazine versus quetiapineIn the short term, there appeared to be no difference in clinical response (as defined in each study) between chlorpromazine or quetiapine (28 RCTs, N = 3241; RR 0.93, 95% CI 0.81 to 1.06, moderate quality evidence) nor in average endpoint score using the BPRS for mental state (6 RCTs, N = 548; MD -0.18, 95% CI -1.23 to 0.88, very low quality evidence). Quality of life ratings using the GQOL1-74 scale were significantly more favourable with people receiving quetiapine (1 RCT, N = 59; MD -6.49, 95% CI -11.30 to -1.68, very low quality evidence). Significantly more people receiving chlorpromazine experienced extrapyramidal adverse effects (8 RCTs, N = 644; RR 8.03, 95% CI 4.78 to 13.51, low quality of evidence). There was no difference between groups for people leaving the studies early in the short term (12 RCTs, N = 1223; RR 1.04, 95% CI 0.77 to 1.41,moderate quality evidence).

AUTHORS' CONCLUSIONS

Most included trials included inpatients from hospitals in China. Therefore the results of this Cochrane review are more applicable to the Chinese population. Mostincluded trials were short term studies, therefore we cannot comment on the medium and long term use of chlorpromazine compared to atypical antipsychotics. Low qualityy evidence suggests chlorpromazine causes more extrapyramidal adverse effects. However, all studiesused varying dose ranges, and higher doses would be expected to be associated with more adverse events.

Dopamine Targeting Drugs for the Treatment of Schizophrenia: Past, Present and Future

Schizophrenia is a chronic and debilitating neuropsychiatric disorder affecting approximately 1% of the world's population. This disease is associated with considerable morbidity placing a major financial burden on society. Antipsychotics have been the mainstay of the pharmacological treatment of schizophrenia for decades. The traditional typical and atypical antipsychotics demonstrate clinical efficacy in treating positive symptoms, such as hallucinations and delusions, while are largely ineffective and may worsen negative symptoms, such as blunted affect and social withdrawal, as well as cognitive function. The inability to treat these latter symptoms may contribute to social function impairment associated with schizophrenia. The dysfunction of multiple neurotransmitter systems in schizophrenia suggests that drugs selectively targeting one neurotransmission pathway are unlikely to meet all the therapeutic needs of this heterogeneous disorder. Often, however, the unintentional engagement of multiple pharmacological targets or even the excessive engagement of intended pharmacological targets can lead to undesired consequences and poor tolerability. In this article, we will review marketed typical and atypical antipsychotics and new therapeutic agents targeting dopamine receptors and other neurotransmitters for the treatment of schizophrenia. Representative typical and atypical antipsychotic drugs and new investigational drug candidates will be systematically reviewed and compared by reviewing structure-activity relationships, pharmacokinetic properties, drug metabolism and safety, pharmacological properties, preclinical data in animal models, clinical outcomes and associated side effects.

Effects of clozapine on perceptual abnormalities and sensory gating: a preliminary cross-sectional study in schizophrenia

The aim of the present study was to investigate the effect of second-generation antipsychotics (clozapine or another second-generation antipsychotic) on perceptual abnormalities related to sensory gating deficit. Although clozapine is known to improve sensory gating assessed neurophysiologically, we hypothesized that patients with schizophrenia treated with clozapine would report less perceptual abnormalities related to sensory gating deficit than patients treated with other second-generation antipsychotics do. Forty patients with a diagnosis of schizophrenia were investigated (10 patients treated with clozapine and 30 patients treated with another second-generation antipsychotic drug). Perceptual abnormalities were assessed with the Sensory Gating Inventory. Sensory gating was assessed through electroencephalogram with the auditory event-related potential method by measuring P50 amplitude changes in a dual click conditioning-testing procedure. Patients treated with clozapine present normal sensory gating and report less perceptual abnormalities related to sensory gating than patients treated with other second-generation antipsychotics do. Although the cross-sectional design of this study is limited because causal inferences cannot be clearly concluded, the present study suggests clinical and neurophysiological advantages of clozapine compared with other second-generation antipsychotics and provides a basis for future investigations on the effect of this treatment on perceptual abnormalities related to sensory gating deficit in patients with schizophrenia.

Aripiprazole-associated tic in a schizophrenia patient

Tic disorder, characterized by the presence of both motor and vocal tics is common in adolescents and adults. Antipsychotics including typical antipsychotics and atypical antipsychotics are generally recognized by experts as the most effective pharmacological treatment for tics. However, previous studies suggest that tic-like symptoms might manifest during treatment with atypical antipsychotics such as clozapine, quetiapine, but not aripiprazole. We present the first case, to our knowledge, of an adult schizophrenia patient who developed tics during treatment with aripiprazole.

Synthesis and evaluation of amide, sulfonamide and urea – benzisoxazole derivatives as potential atypical antipsychotics

A series of amide derivatives of benzisoxazole has been synthesized and the target compounds evaluated for atypical antipsychotic activity in vitro and vivo.

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.

Paliperidone extended-release: safety and tolerability from a metabolic profile perspective

Pharmacologic management strategies for schizophrenia, a relatively common psychotic disorder, include the use of typical and atypical antipsychotic drugs. In general, typical (or conventional) antipsychotics have a proven track record in effectively managing the positive symptoms of schizophrenia but sometimes lack efficacy in treating negative symptoms. The conventional agents are also associated with adverse neurologic effects such as extrapyramidal symptoms (EPS). The development of atypical antipsychotics has partly ameliorated the issue of EPS induced by typical antipsychotics. However, several of these atypical antipsychotic agents have been associated with adverse metabolic effects, including weight gain, dyslipidemia, and increased serum glucose levels. Paliperidone (9-hydroxy-riperidone) extended-release (ER) is an atypical antipsychotic indicated for the treatment of schizophrenia which utilizes a patented oral osmotic system technology that provides constant drug delivery over the course of the day. The efficacy and safety of paliperidone ER in patients with schizophrenia have been established. This review focuses on the metabolic safety of paliperidone ER in patients with schizophrenia. Clinical trials have demonstrated a lack of significant change in lipid profiles with paliperidone ER; furthermore, reported incidences of glucose-related adverse events in clinical trials were very low and similar to those seen with placebo. While dose-related increases in bodyweight of 1-2 kg have been observed with paliperidone ER, there are few reports of clinically relevant increases in bodyweight during treatment. Placebo-controlled trials indicate that the risk of developing metabolic disorders with paliperidone ER is low and similar to that seen with placebo. Furthermore, the ER formulation of paliperidone may offer potential advantages over atypical antipsychotics such as risperidone, particularly with regard to side effects and compliance, but comparative studies are needed.

Design and synthesis of novel 2H-chromen-2-one derivatives bearing 1,2,3-triazole moiety as lead antimicrobials

A series of novel 2H-chromen-2-one derivatives decorated with 1,2,3-triazole moiety were designed and synthesized using the click reaction of azidoalkyloxy-2H-chromen-2-ones with different propargylamines. Propargylamines were obtained by alkylation of various heterocyclic amines with propargyl bromide. Newly synthesized compounds and intermediates were evaluated for their antifungal activity against four fungi (Aspergillus niger, Aspergillus fumigatus, Aspergillus flavus and Candida albicans). Antibacterial studies were also carried out against three Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis and Staphylococcus epidermis) and four Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Klebsiella pneumoniae). In vitro, bioassay results showed that all the synthesized compounds exhibited excellent activity against fungal strains Aspergillus fumigatus, Aspergillus flavus and Candida albicans. Interestingly, all the compounds have shown even superior activity than the reference drug miconazole against Aspergillus fumigatus. Morpholine and N-acetyl piperazine containing compounds 10c and 10e have shown promising activity against various bacterial strains. Compound 10e was found to be most active against Pseudomonas aeruginosa. Based on, in silico pharmacokinetic studies, compounds 10a-e were identified as lead compounds for future investigation due to their lower toxicity, high drug score values and good oral bioavailability as per OECD guidelines.

Synthesis and evaluation of new coumarin derivatives as potential atypical antipsychotics

In this paper, we report the synthesis of novel, potential antipsychotic coumarin derivatives combining potent dopamine D₂, D₃ and serotonin 5-HT(1A), 5-HT(2A) receptors properties. We describe the structure activity relationship that leads us to the promising derivative: 7-(4-(4-(6-fluorobenzo[d]isoxazol-3-yl)piperidin-1-yl)butoxy)-6-methyl-2,3-dihydrocyclopenta[c]chromen-4(1H)-one 27. The unique pharmacological features of compound 27 are a high affinity for dopamine D₂, D₃ and serotonin 5-HT(1A), 5-HT(2A) receptors, together with a low affinity for H₁ receptor (to reduce the risk of obesity under chronic treatment). In animal models, compound 27 inhibited apomorphine-induced climbing and MK-801-induced hyperactivity without observable catalepsy at the highest dose tested. In particular, compound 27 was more potent than clozapine.

The effectiveness of treatments for cocaine dependence in schizophrenic patients: a systematic review

Objectives:

To evaluate and compare the effectiveness of available treatments for cocaine dependence in schizophrenic patients.

Method:

We searched articles published between May 2002 and June 2012 in the following databases: Scopus, Pubmed and Web of Knowledge. The key words utilised were “schizophrenia”, "dementia praecox", "schizophrenic disorder", "cocaine related disorder", "cocaine abuse", "cocaine addiction", "cocaine dependence", “treatment”, “therapeutic”, and "drug therapy”.

Selection of studies and data extraction:

Original articles in English, Portuguese and Spanish were selected. Controlled, double-blind and open-label studies involving only human subjects were included in this review.

Data Synthesis:

We found studies on typical and atypical antipsychotics and one monoamine transporter antagonist. There were few indications of the effectiveness of atypical antipsychotic medications for the treatment of cocaine dependence in patients with schizophrenia.

Conclusions:

We suggest that further studies be conducted with atypical antipsychotic medicationsand greater methodological strictness, including using a placebo group in the studies, so that health professionals can determine the real effectiveness of this class of medication for the treatment of cocaine dependence in schizophrenic patients.

Quinoline- and isoquinoline-sulfonamide analogs of aripiprazole: novel antipsychotic agents?

The introduction of typical antipsychotics over six decades ago signaled an important milestone in psychiatry. However, second-generation antipsychotics ameliorated the positive symptoms of schizophrenia but displayed limited effectiveness for the negative and cognitive symptoms. In addition, while the newer antipsychotics produced fewer motor side effects, the atypical antipsychotics still induced weight gain and endocrinopathies. In recent years, a third generation of antipsychotics was identified. Aripiprazole was the first approved drug acting as a D2 partial agonist/functionally selective ligand. This review presents the state of the development of novel antipsychotic dopaminergic and non-dopaminergic agents, supported by an overview of the compounds evaluated under advanced preclinical and clinical development (e.g., cariprazine and brexpiprazole). In line with the recent trends in the development of modern atypical antipsychotics, we present our strategic development of long-chain arylpiperazine-derived quinoline- and isoquinoline-sulfonamide displaying a multireceptor binding profile and partial D2 receptor agonism.

Dopamine D3 and 5-HT1B receptor dysregulation as a result of psychostimulant intake and forced abstinence: Implications for medications development

Addiction to psychostimulants, including cocaine and amphetamine, is associated with dysregulation of dopamine and serotonin (5-HT) neurotransmitter systems. Neuroadaptations in these systems vary depending on the stage of the drug taking-abstinence-relapse cycle. Consequently, the effects of potential treatments that target these systems may vary depending on whether they are given during abstinence or relapse. In this review, we discuss evidence that dopamine D3 receptors (D3Rs) and 5-HT1B receptors (5-HT1BRs) are dysregulated in response to both chronic psychostimulant use and subsequent abstinence. We then review findings from preclinical self-administration models which support targeting D3Rs and 5-HT1BRs as potential medications for psychostimulant dependence. Potential side effects of the treatments are discussed and attention is given to studies reporting positive treatment outcomes that depend on: 1) whether testing occurs during self-administration versus abstinence, 2) whether escalation of drug self-administration has occurred, 3) whether the treatments are given repeatedly, and 4) whether social factors influence treatment outcomes. We conclude that D3/D2 agonists may decrease psychostimulant intake; however, side effects of D3/D2R full agonists may limit their therapeutic potential, whereas D3/D2R partial agonists have fewer undesirable side effects. D3-selective antagonists may not reduce psychostimulant intake during relapse, but nonetheless, may decrease motivation for seeking psychostimulants with relatively few side-effects. 5-HT1BR agonists provide a striking example of treatment outcomes that are dependent on the stage of the addiction cycle. Specifically, these agonists initially increase cocaine's reinforcing effects during maintenance of self-administration, but after a period of abstinence they reduce psychostimulant seeking and the resumption of self-administration. In conclusion, we suggest that factors contributing to dysregulation of monoamine systems, including drug history, abstinence, and social context, should be considered when evaluating potential treatments to better model treatment effects in humans. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

Paliperidone protects prefrontal cortical neurons from damages caused by MK-801 via Akt1/GSK3β signaling pathway

Recent studies have suggested that neurodegeneration is involved in the pathogenesis of schizophrenia, and some atypical antipsychotics appear to prevent or retard progressive morphological brain changes. However, the underlying molecular mechanisms are largely unknown. Whether changes in intracellular signaling pathways are related to their neuroprotective effects remains undefined. In the present study, we used mouse embryonic prefrontal cortical neurons to examine the neuroprotection of paliperidone against the neuronal damage induced by exposure to the NMDA receptor antagonist, MK-801. Paliperidone inhibited MK-801 induced neurotoxicity both in MTT metabolism assay (p<0.01) and in lactate dehydrogenase (LDH) activity assay (p<0.01). Time course studies revealed that paliperidone effectively attenuated the elevation of intracellular free calcium concentration ([Ca(2+)]i) induced by exposure to MK-801 (p<0.01). Moreover, paliperidone could significantly retard MK-801-mediated inhibition of neurite outgrowth (p<0.01) and reverse MK-801-induced decreases of gene expression and phosphorylation of Akt1 and GSK3β (both p<0.01). Furthermore, these protective effects of paliperidone were blocked by pretreatment with a PI3K inhibitor LY294002. Taking together, our results demonstrated that paliperidone could protect prefrontal cortical neurons from MK-801-induced damages via Akt1/GSK3β signaling pathway.

Effect of D-cycloserine in conjunction with fear extinction training on extracellular signal-regulated kinase activation in the medial prefrontal cortex and amygdala in rat

D-cycloserine (DCS) is currently under clinical trials for a number of neuropsychiatric conditions and has been found to augment fear extinction in rodents and exposure therapy in humans. However, the molecular mechanism of DCS action in these multiple modalities remains unclear. Here, we describe the effect of DCS administration, alone or in conjunction with extinction training, on neuronal activity (c-fos) and neuronal plasticity [phospho-extracellular signal-regulated kinase (pERK)] markers using immunohistochemistry. We found that intraperitoneal administration of DCS in untrained young rats (24-28 days old) increased c-fos- and pERK-stained neurons in both the prelimbic and infralimbic division of the medial prefrontal cortex (mPFC) and reduced pERK levels in the lateral nucleus of the central amygdala. Moreover, DCS administration significantly increased GluA1, GluN1, GluN2A, and GluN2B expression in the mPFC. In a separate set of animals, we found that DCS facilitated fear extinction and increased pERK levels in the infralimbic prefrontal cortex, prelimbic prefrontal cortex intercalated cells and lateral nucleus of the central amygdala, compared with saline control. In the synaptoneurosomal preparation, we found that extinction training increased iGluR protein expression in the mPFC, compared with context animals. No significant difference in protein expression was observed between extinction-saline and extinction-DCS groups in the mPFC. In contrast, in the amygdala DCS, the conjunction with extinction training led to an increase in iGluR subunit expression, compared with the extinction-saline group. Our data suggest that the efficacy of DCS in neuropsychiatric disorders may be partly due to its ability to affect neuronal activity and signaling in the mPFC and amygdala subnuclei.

Antipsychotic compounds differentially modulate high-frequency oscillations in the rat nucleus accumbens: a comparison of first- and second-generation drugs

Improved understanding of the actions of antipsychotic compounds is critical for a better treatment of schizophrenia. Abnormal oscillatory activity has been found in schizophrenia and in rat models of the disease. N-Methyl-D-aspartic acid receptor (NMDAR) antagonists, used to model certain features of schizophrenia, increase the frequency and power of high-frequency oscillations (HFO, 130-180 Hz) in the rat nucleus accumbens, a brain region implicated in schizophrenia pathology. Antipsychotics can be classified as first- and second-generation drugs, the latter often reported to have wider benefit in humans and experimental models. This prompted the authors to examine the pre- and post-treatment effects of clozapine, risperidone (second-generation drugs) and sulpiride and haloperidol (first-generation drugs) on ketamine and MK801-enhanced accumbal HFO. Both NMDAR antagonists increased HFO frequency. In contrast, clozapine and risperidone markedly and dose-dependently reduced the frequency of spontaneous and NMDAR-antagonist-enhanced HFO, whilst a moderate effect was found for sulpiride and a much weaker effect for haloperidol. Unexpectedly, we found reductions in HFO frequency were associated with an increase in its power. These findings indicate that modulation of accumbal HFO frequency may be a fundamental effect produced by antipsychotic compounds. Of the drugs investigated, first- and second-generation compounds could be dissociated by their potency on this measure. This effect may partially explain the differences in the clinical profile of these drugs.

Teaching Application of Clinical Pharmacology Skills Using Unusual Observations from Clozapine Overdoses

Massive drug overdoses provide a unique opportunity to observe human pharmacokinetic data not otherwise ethically available. They can also provide practical examples for teaching thoughtful application of the principles of clinical pharmacology. Following a case of clozapine overdose in which onset of toxicity was delayed by 72 hours, a probable explanation was found in an exploration of three cases with unusual concentration-time profiles and revealed unexpected implications for the management of clozapine overdoses. The authors systematically addressed the possible mechanisms proposed in the literature for an unusual plateau in concentrations observed in three clozapine overdoses. The effects that the most commonly suggested explanations (i.e., delayed absorption and saturated or impaired metabolism) would have on both clozapine and norclozapine concentrations were then modeled using the data available from those three cases to provide an objective illustration for comparison. This exercise was then used as a teaching seminar, leading students through the steps required to reach a logical explanation for the observed delayed toxicity and to consider the implications for therapy. Delayed absorption best predicted the sustained serum clozapine and norclozapine concentrations observed in three cases, and modeling suggests that much of the drug remains in the gut, available for absorption for days following an overdose. As a seminar, the exercise provides students with a practical example of the value of systematically ruling out possible explanations by considering what effects various pharmacokinetic alterations would have on observed data. Absorption following massive clozapine overdose appears fundamentally different from that with conventional dosing. This suggests a potential for delayed or prolonged toxicity, extending well beyond the time frame predicted by its half-life, unless aggressive and sustained efforts are applied to remove clozapine from the gut. Data from drug overdoses provide opportunities to explore unusual aspects of pharmacokinetics, better understand future overdoses of the same agent, and present excellent material for teaching. A seminar illustrating the role that thoughtful application of pharmacologic principles had in addressing this case is now used to introduce the clinical aspects of pharmacology to students at our institutions.

Olanzapine-induced diabetic ketoacidosis and neuroleptic malignant syndrome with rhabdomyolysis: a case report

Atypical antipsychotics have replaced conventional antipsychotics in the treatment of schizophrenia because they have less of a propensity to cause undesirable neurologic adverse events including extrapyramidal symptoms, tardive dyskinesia, and neuroleptic malignant syndrome (NMS). However, atypical antipsychotics have been known to result in various metabolic complications such as impaired glucose tolerance, diabetes and even diabetic ketoacidosis (DKA). In addition, a number of NMS cases have been reported in patients treated with atypical antipsychotics, although the absolute incidence of neurologic side effects is currently significantly low. Here, we report a patient who simultaneously developed DKA, acute renal failure and NMS with rhabdomyolysis after olanzapine treatment. Olanzapine-induced metabolic complications and NMS were dramatically improved with cessation of the olanzapine treatment and initiation of supportive management including fluid therapy, hemodialysis, and intensive glycemic control using insulin. At short-term follow-up, insulin secretion was markedly recovered as evidenced by a restoration of serum C-peptide level, and the patient no longer required any hypoglycemic medications. Despite the dramatic increase in the use of atypical antipsychotics treatment, individualized treatments along with careful monitoring may be prudent for high risk or vulnerable patients in order to avoid the development of metabolic side effects.

Effects of antipsychotic drugs on the expression of synaptic proteins and dendritic outgrowth in hippocampal neuronal cultures

Recent evidence has suggested that atypical antipsychotic drugs regulate synaptic plasticity. We investigated whether some atypical antipsychotic drugs (olanzapine, aripiprazole, quetiapine, and ziprasidone) altered the expression of synapse-associated proteins in rat hippocampal neuronal cultures under toxic conditions induced by B27 deprivation. A typical antipsychotic, haloperidol, was used for comparison. We measured changes in the expression of various synaptic proteins including postsynaptic density protein-95 (PSD-95), brain-derived neurotrophic factor (BDNF), and synaptophysin (SYP). Then we examined whether these drugs affected the dendritic morphology of hippocampal neurons. We found that olanzapine, aripiprazole, and quetiapine, but not haloperidol, significantly hindered the B27 deprivation-induced decrease in the levels of these synaptic proteins. Ziprasidone did not affect PSD-95 or BDNF levels, but significantly increased the levels of SYP under B27 deprivation conditions. Moreover, olanzapine and aripiprazole individually significantly increased the levels of PSD-95 and BDNF, respectively, even under normal conditions, whereas haloperidol decreased the levels of PSD-95. These drugs increased the total outgrowth of hippocampal dendrites via PI3K signaling, whereas haloperidol had no effect in this regard. Together, these results suggest that the up-regulation of synaptic proteins and dendritic outgrowth may represent key effects of some atypical antipsychotic drugs but that haloperidol may be associated with distinct actions.

Comparative effectiveness of antipsychotic drugs in schizophrenia

Chlorpromazine, which was discovered in 1952, has an exhaustively characterized efficacy/safety profile comprising serious limitations: effectiveness in the field failing to match efficacy in trials, residual symptoms in 50% of patients, a 20% relapse rate in compliant patients, and worrisome extrapyramidal side effects, including tardive dyskinesia in 5% per year. Second-generation "atypical" antipsychotics bypass these effects by having less affinity for the dopamine D(2) receptor and affinities for other neuroreceptors. Clozapine, the lead atypical antipsychotic, was followed in the mid 1990s by risperidone, olanzapine, and quetiapine, which now account for over half of new antipsychotic prescriptions in North America, The debate over their relative efficacy involves the potential well-being of millions of schizophrenics and billions of dollars. Atypical antipsychotics are considerably more expensive; evidence for their superiority is highly variable and often inadequate, largely confined to short-term regulatory studies. Their effects on long-term outcome (particularly negative symptoms), relapse prevention, social and vocational functioning, suicide prevention and quality of life, and family and caregiver burden are largely unknown. The National institute of Mental Health's Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) project is a combined efficacy-effectiveness trial that aims to answer these questions in a broad range of patients with schizophrenia and Alzheimer's disease.

Treatment Response in First-episode Schizophrenia

First episode schizophrenia (FES) patients tend to be more responsive to treatment. An adequate response has been associated with a favourable long-term course in FES patients. Yet, despite the generally very favourable response profile around one quarter of the patients shows persisting symptoms of psychosis. To improve the outcome and course of psychosis great effort has emerged in identifying biological and clinical variables associated with non-response in order to identify non-responders as early as possible and adopt specific treatment strategies improving illness outcome. Different antipsychotic treatment regimens have been evaluated in terms of their efficacy in reducing symptoms of FES with psychological interventions gaining increasing importance in the treatment concept of patients suffering from their first illness episode. Therefore, aim of this review is to summarize current evidence on the response patterns, the most important predictors of response/non-response as well as on effective treatment interventions in FES patients.

Effects of aripiprazole and clozapine on the treatment of glycolytic carbon in PC12 cells

Aripiprazole is the only atypical antipsychotic drug known to cause the phosphorylation of AMP-activated protein kinase (AMPK) in PC12 cells. However, the molecular mechanisms underlying this phosphorylation in aripiprazole-treated PC12 cells have not yet been clarified. Here, using PC12 cells, we show that these cells incubated for 24 h with aripiprazole at 50 μM and 25 mM glucose underwent a decrease in their NAD⁺/NADH ratio. Aripiprazole suppressed cytochrome c oxidase (COX) activity but enhanced the activities of pyruvate dehydrogenase (PDH), citrate synthase and Complex I. The changes in enzyme activities coincided well with those in NADH, NAD⁺, and NAD⁺/NADH ratio. However, the bioenergetic peril judged by the lowered COX activity might not be accompanied by excessive occurrence of apoptotic cell death in aripiprazole-treated cells, because the mitochondrial membrane potential was not decreased, but rather increased. On the other hand, when PC12 cells were incubated for 24 h with clozapine at 50 μM and 25 mM glucose, the NAD⁺/NADH ratio did not change. Also, the COX activity was decreased; and the PDH activity was enhanced. These results suggest that aripiprazole-treated PC12 cells responded to the bioenergetic peril more effectively than the clozapine-treated ones to return the ATP biosynthesis back toward its ordinary level. This finding might be related to the fact that aripiprazole alone causes phosphorylation of AMPK in PC12 cells.

Clozapine, atypical antipsychotics, and the benefits of fast-off D2 dopamine receptor antagonism

Drug-receptor interactions are traditionally quantified in terms of affinity and efficacy, but there is increasing awareness that the drug-on-receptor residence time also affects clinical performance. While most interest has hitherto been focused on slow-dissociating drugs, D(2) dopamine receptor antagonists show less extrapyramidal side effects but still have excellent antipsychotic activity when they dissociate swiftly. Fast dissociation of clozapine, the prototype of the "atypical antipsychotics", has been evidenced by distinct radioligand binding approaches both on cell membranes and intact cells. The surmountable nature of clozapine in functional assays with fast-emerging responses like calcium transients is confirmatory. Potential advantages and pitfalls of the hitherto used techniques are discussed, and recommendations are given to obtain more precise dissociation rates for such drugs. Surmountable antagonism is necessary to allow sufficient D(2) receptor stimulation by endogenous dopamine in the striatum. Simulations are presented to find out whether this can be achieved during sub-second bursts in dopamine concentration or rather during much slower, activity-related increases thereof. While the antagonist's dissociation rate is important to distinguish between both mechanisms, this becomes much less so when contemplating time intervals between successive drug intakes, i.e., when pharmacokinetic considerations prevail. Attention is also drawn to the divergent residence times of hydrophobic antagonists like haloperidol when comparing radioligand binding data on cell membranes with those on intact cells and clinical data.

Varenicline as a smoking cessation aid in schizophrenia: effects on smoking behavior and reward sensitivity

RATIONALE

Smoking rates are up to five times higher in people with schizophrenia than in the general population, placing these individuals at high risk for smoking-related health problems. Varenicline, an α4β2 nicotinic acetylcholine receptor partial agonist, is a promising aid for smoking cessation in this population. To maximize treatment efficacy while minimizing risks, it is critical to identify reliable predictors of positive response to varenicline in smokers with schizophrenia.

OBJECTIVES

Negative symptoms of schizophrenia are related to dysfunctions in the brain reward system, are associated with nicotine dependence, and may be improved by nicotine or nicotinic receptor agonists, suggesting that smoking cessation may be especially difficult for patients with substantial negative symptoms. The purpose of the study was to evaluate negative symptoms as predictors of response to varenicline.

METHODS

Patients with schizophrenia (N = 53) completed a 12-week smoking cessation trial combining varenicline with cognitive behavioral therapy. Negative symptoms were assessed via the Scale for the Assessment of Negative Symptoms (Andreasen 1983). Outcomes included smoking abstinence as assessed by self-report and expired carbon monoxide. Change in performance on a probabilistic reward task was used as an index of change in reward sensitivity during treatment.

RESULTS

At week 12, 32 participants met criteria for 14-day point-prevalence abstinence. Patients with lower baseline symptoms of affective flattening (more typical affect) were more likely to achieve smoking abstinence and demonstrated larger increases in reward sensitivity during treatment.

CONCLUSIONS

These data suggest that affective flattening symptoms in smokers with schizophrenia may predict response to varenicline.

Olanzapine stimulates proliferation but inhibits differentiation in rat oligodendrocyte precursor cell cultures

In the developing brain, oligodendrocyte progenitor cells (OPCs) proliferate, migrate, and differentiate into mature oligodendrocytes (OLs) capable of myelinating axons. Recently, OPCs have been identified as an abundant and widespread population in the adult as well as in the developing animal. Current research indicates that these OPCs in the adult brain can proliferate and differentiate into myelinating OLs, albeit with different potentialities from those in developing animals. Multiple lines of evidence, from neuroimaging, postmortem, and genetic association studies, have implicated OL and myelin dysfunction in the pathogenesis of schizophrenia. If altered OL function is involved in pathogenesis, OPCs may thus respond to antipsychotic drugs during the recovery process. In the present study, we used primary OPC cultures from optic nerve of newborn Wistar rat pups to investigate the direct effects of haloperidol (HPD; a typical antipsychotic) and olanzapine (OLZ; an atypical antipsychotic) on the proliferation and differentiation of OPCs. Our results showed that 1) OLZ treatment significantly increased the number of viable OPCs when compared to HPD treatment at relatively high concentrations, 2) OLZ treatment suppressed the expression of myelin basic protein (MBP), and to a greater extent than HPD treatment, and 3) these pharmacological effects may be mediated via the ERK signaling pathway. Our findings suggest a glial mechanism for the antipsychotic action of OLZ, and a role for oligodendrocyte-lineage cells in the pathogenesis and treatment of schizophrenia.

Neuroprotection of paliperidone on SH-SY5Y cells against β-amyloid peptide(25-35), N-methyl-4-phenylpyridinium ion, and hydrogen peroxide-induced cell death

RATIONALE

Antipsychotic drugs (APDs) were widely used in treating schizophrenia. Some APDs were reported to have neuroprotective effects against neurotoxicants in the cell level.

OBJECTIVES

Thus, one typical APD (haloperidol) and three atypical APDs (paliperidone, olanzapine, and risperidone) were tested whether they provide neuroprotection against stressor-induced cell death of SH-SY5Y.

METHODS

Hydrogen peroxide, N-methyl-4-phenylpyridinium ion, and β-amyloid peptide were used to treat cells with or without preconditioning by APDs; cell survival and indicators of oxidative stress were measured, respectively.

RESULTS

Paliperidone has the lowest baseline cytotoxicity compared with other APDs at 24 h; in addition, the paliperidone group showed a better survival than the other APD groups (P < 0.05). In stressor challenging, with a fixed concentration of stressors, olanzapine provided the best neuroprotection at 100 μM against Aβ(25-35) and MPP(+) (P < 0.05). In contrast, paliperidone works finely at low concentrations (10 and 50 μM) against Aβ(25-35) and MPP(+) and solely protected SH-SY5Y from hydrogen peroxide. At 100 μM, paliperidone completely diminished cell reduction induced by different stressors, regardless of their dosages. Paliperidone was demonstrated with a higher oxidative stress-scavenging properties than other APDs in several aspects, such as generated bulk glutathione, low HNE, and protein carbonyl productions. Contradictorily, olanzapine, at 24 h, also enhanced HNE and protein carbonyl productions, which may underlie its induced cytotoxicity.

CONCLUSIONS

Different APDs exhibit variations against different stressors. Paliperidone might be useful not only in alleviating oxidative stress induced by Aβ(25-35) and MPP(+) but also in providing neuroprotection against hydrogen peroxide.

Factors affecting interindividual differences in clozapine response: a review and case report

OBJECTIVE

Clozapine is the most powerful new‐generation antipsychotic. Although this drug leads to great therapeutic benefits, two types of undesirable conditions frequently occur with its use: side effects and resistance to treatment. Therapeutic drug monitoring of clozapine would be very useful to avoid both these situations. The necessity of monitoring the therapy is the result of a wide interindividual variability in the metabolism of clozapine. In this review, we highlight all the conditions underlying this variability, analyzing them one by one.

METHODS

Relevant literature was identified through a search of MEDLINE and PubMed. In addition, the case of a treatment‐resistant patient with accelerated metabolism of clozapine is reported as representative of utility of therapeutic drug monitoring in terms of clozapine dose adjustment.

RESULTS

Genetic polymorphisms of cytochrome P450 enzymes and of neurotransmitter receptors; drug interactions; interactions of clozapine with other substances such as food and drink; smoking; and nonmodifiable variables such as age, ethnicity, and gender have been examined in relation to the existing scientific literature. The laboratory techniques that clinicians could use to identify these variables and adequate therapies are also reviewed.