Amisulpride: a review of its use in the management of schizophrenia

Photodegradation of psychotropic medications: Impact on efficacy, safety, and drug properties

Antipsychotics and antidepressants are essential psychotropic medications used for treating various mental health conditions such as depression, schizophrenia, and bipolar disorder. However, when exposed to light, these compounds are susceptible to photodegradation, potentially changing their biological activity and safety profiles. This study evaluates the pharmacokinetic and pharmacodynamic properties of several photoproducts derived from 13 psychotropic drugs. We used computational methods to predict the biological activity, toxicity, and drug-like properties of the photoproducts. Our results indicate that photoproducts such as amisulpride_TP166, TP246, quetiapine_D4, and quetiapine_PH1 show enhanced biological affinity and ADME-Tox profiles similar to their parent compounds, suggesting possible therapeutic advantages in their interaction with targeted receptors. However, some of the photocompounds exhibit lower predicted binding affinities when interacting with those receptors compared to their parent compounds, indicating a possible loss of function. These findings emphasize the need for further investigation into the effects and safety of drug photoproducts, particularly in the context of long-term pharmacotherapy.

Recent Advances in representative small-molecule DRD2 inhibitors: Synthetic Routes and clinical applications

The dopamine D2 receptor (DRD2) represents a pivotal target for therapeutic intervention in the treatment of neuropsychiatric disorders, including schizophrenia, bipolar disorder, and Parkinson's disease. The successful discovery of numerous effective DRD2 inhibitors has led to their clinical application and ongoing evaluation in various clinical trials. This review explores the synthetic approaches and clinical applications of prototypical small-molecule DRD2 inhibitors that have received approval or are currently undergoing clinical trials, highlighting their therapeutic potential and challenges. The synthesis of these inhibitors employs various chemical strategies, including modifications of phenothiazine and butyrophenone structures, which have yielded significant antipsychotic agents like chlorpromazine and haloperidol. Additionally, newer classes of inhibitors, such as aripiprazole, exhibit partial agonist activity at DRD2, offering a unique therapeutic profile. Clinically, DRD2 inhibitors demonstrate efficacy in managing positive symptoms of schizophrenia, manic episodes in bipolar disorder, and dopaminergic imbalance in Parkinson's disease. However, the emergence of adverse effects, including tardive dyskinesia, extrapyramidal symptoms and metabolic syndrome, presents substantial challenges. Advances in the development of second-generation antipsychotics aim to balance efficacy with a better side effect profile by targeting additional neurotransmitter receptors. This review aims to deliver an overview of the synthesis and clinical applications of representative small-molecule DRD2 inhibitors across various clinical phases, thereby offering strategic insights for the advancement of DRD2 inhibitor development.

Efficacy and safety of low-dose amisulpride versus olanzapine-fluoxetine combination in post-schizophrenic depression: A randomized controlled trial

Post-schizophrenic depression (PSD) increases the morbidity, mortality, and health burden in patients with schizophrenia. However, treatment of PSD is challenging due to the lack of substantial evidence of standard clinical practice. This study was aimed at comparing the efficacy and safety of low-dose amisulpride versus olanzapine-fluoxetine combination (OFC) in PSD. This was a randomized controlled trial conducted in sixty patients with PSD fulfilling the eligibility criteria. Recruited patients were randomized to receive either amisulpride at low dose (i.e., 100-300 mg/day) or OFC (5/10 mg + 20 mg) for eight weeks. The Calgary Depression Scale for Schizophrenia (CDSS), the Clinical Global Impression-Severity (CGI-S) and serum BDNF levels were assessed at baseline and after eight weeks of treatment. The change in the CDSS scores from baseline over eight weeks was significant in both the amisulpride and OFC groups. However, the changes were not significant when compared between the groups. Similarly, the changes in CGI-S scores and serum BDNF levels were significant in each group; but non-significant between the groups. A significant negative correlation was found between the changes in the CDSS scores and the serum BDNF levels in each group. No significant adverse events were noted in either group. Thus, to conclude, low-dose amisulpride can be a potential monotherapy in PSD with a favourable clinical outcome and safety profile (ClinicalTrials.gov ID: NCT04876521).

Age, Sex, and Comedication Effects on the Steady-State Plasma Concentrations of Amisulpride in Chinese Patients with Schizophrenia

BACKGROUND

Amisulpride, a second-generation atypical antipsychotic drug, was first marketed in Europe in the 1990s. This study aimed to provide a reference for the clinical application of amisulpride. The effects of age, sex, or specific comedications on amisulpride concentrations in Chinese patients with schizophrenia in the real world were investigated.

METHODS

A retrospective study was conducted of data on amisulpride based on the therapeutic drug monitoring service database at the Zigong Affiliated Hospital of Southwest Medical University.

RESULTS

Based on the inclusion criteria, 195 plasma samples from 173 patients (67.05% female and 32.95% male patients) were included for in-depth analysis. The median daily dose of amisulpride was 400 mg/d, median plasma concentration was 457.50 ng/mL, and median concentration/dose (C/D) ratio was 1.04 ng/mL/mg/d. The daily dose of amisulpride positively correlated with measured steady-state plasma concentrations. A significant difference was observed in the subgroup analysis of the combination with valproic acid, zopiclone, or aripiprazole on plasma concentrations. Combining amisulpride with these drugs increased the C/D ratios by 0.56-, 2.31-, and 0.77-fold, respectively. After adjusting for age, the median C/D ratio was found to be significantly different between female and male patients. However, no significant differences in daily dose, plasma concentration, and C/D ratio were noted with respect to sex and age of the patients.

CONCLUSIONS

Sex differences were inferred for the first time in this study, with differential effects on daily dose, steady-state plasma concentration, and C/D ratio associated with the population. In the included study samples, blood concentrations were distributed in the range of 223.25-823.55 ng/mL, which perhaps needs to be evaluated in line with the reference range of ammonia-sulfur ratios in the Chinese population.

Population pharmacokinetics of Amisulpride in Chinese patients with schizophrenia with external validation: the impact of renal function

Introduction: Amisulpride is primarily eliminated via the kidneys. Given the clear influence of renal clearance on plasma concentration, we aimed to explicitly examine the impact of renal function on amisulpride pharmacokinetics (PK) via population PK modelling and Monte Carlo simulations. Method: Plasma concentrations from 921 patients (776 in development and 145 in validation) were utilized. Results: Amisulpride PK could be described by a one-compartment model with linear elimination where estimated glomerular filtration rate, eGFR, had a significant influence on clearance. All PK parameters (estimate, RSE%) were precisely estimated: apparent volume of distribution (645 L, 18%), apparent clearance (60.5 L/h, 2%), absorption rate constant (0.106 h-1, 12%) and coefficient of renal function on clearance (0.817, 10%). No other significant covariate was found. The predictive performance of the model was externally validated. Covariate analysis showed an inverse relationship between eGFR and exposure, where subjects with eGFR= 30 mL/min/1.73 m2 had more than 2-fold increase in AUC, trough and peak concentration. Simulation results further illustrated that, given a dose of 800 mg, plasma concentrations of all patients with renal impairment would exceed 640 ng/mL. Discussion: Our work demonstrated the importance of renal function in amisulpride dose adjustment and provided a quantitative framework to guide individualized dosing for Chinese patients with schizophrenia.

A narrative review of non-racemic amisulpride (SEP-4199) for treatment of depressive symptoms in bipolar disorder and LB-102 for treatment of schizophrenia

INTRODUCTION

The challenges posed by treatment-resistant schizophrenia and depressive symptoms have led to ongoing difficulties despite the availability of antipsychotics and antidepressants. This review addresses the potential of amisulpride analogs, particularly SEP-4199, in addressing these challenges through enhanced efficacy and reduced side effects.

AREAS COVERED

This review focuses on the pharmacological profile of amisulpride analogs, exemplified by LB-102 and its derivative SEP-4199. PubMed gathered articles (up to 10 March 2023) on 'amisulpride,' 'schizophrenia,' 'bipolar disorder,' and 'major depressive disorder;' ClinicalTrials.gov tracked SEP-4199 and LB-102 trials. LB-102, a newly identified N-methylated analog of amisulpride, exhibits enhanced lipophilicity at lower doses, as demonstrated in a phase 1 study, indicating significant promise for therapeutic applications. The discovery of SEP-4199, a non-racemic analog composed of R- and S-enantiomers in an 85:15 ratio, is discussed, emphasizing its potential to enhance antidepressant effects while minimizing extrapyramidal side effects via selective D2 receptor binding. Recent phase 2 trials have demonstrated SEP-4199's efficacy in treating depressive symptoms in bipolar disorder I, capitalizing on D2-mediated anti-anhedonic and D3-mediated reward effects.

EXPERT OPINION

The development of SEP-4199 presents a potential breakthrough for managing depressive symptoms in bipolar disorder I. Further exploration of D2 and D3 receptor-mediated effects could lead to improved treatment strategies.

A Randomized, Double-blind, Placebo-controlled Proof-of-Concept Trial to Evaluate the Efficacy and Safety of Non-racemic Amisulpride (SEP-4199) for the Treatment of Bipolar I Depression

BACKGROUND

Non-racemic amisulpride (SEP-4199) is an 85:15 ratio of aramisulpride:esamisulpride with a 5-HT7 and D2 receptor binding profile optimized for the treatment of bipolar depression. The aim of this study was to evaluate the efficacy and safety of SEP-4199 for the treatment of bipolar depression.

METHODS

Patients meeting DSM-5 criteria for bipolar I depression were randomized to 6 weeks of double-blind, placebo-controlled treatment with SEP-4199 200 mg/d or 400 mg/d. The primary endpoint was change in the Montgomery-Asberg Depression Rating Scale (MADRS) at Week 6. The primary efficacy analysis population consisted of patients in Europe and US (n = 289); the secondary efficacy analysis population (ITT; n = 337) included patients in Japan.

RESULTS

Endpoint improvement in MADRS total score was observed on both the primary analysis for SEP-4199 200 mg/d (P = 0.054; effect size [ES], 0.31) and 400 mg/d (P = 0.054; ES, 0.29), and on the secondary (full ITT) analysis for SEP-4199 200 mg/d (P = 0.016; ES, 0.34) and 400 mg/d (P = 0.024; ES, 0.31). Study completion rates were 81% on SEP-4199 200 mg/d, 88% on 400 mg/d, and 86% on placebo. SEP-4199 had low rates of individual adverse events (<8%) and minimal effects on weight and lipids; median increases in prolactin were +83.6 μg/L on 200 mg/d, +95.2 μg/L on 400 mg/d compared with 0.0 μg/L on placebo.

LIMITATIONS

The study excluded patients with bipolar II depression and serious psychiatric or medical comorbidity.

CONCLUSION

Study results provide preliminary proof of concept, needing confirmation in subsequent randomized trials, for the efficacy of non-racemic amisulpride in bipolar depression.

Effect of a 5-HT7 Receptor Antagonist on Reversal Learning in the Rat Attentional Set-Shifting Test

5-HT7 receptor antagonism has been shown to ameliorate ketamine-induced schizophrenia-like deficits in extradimensional set-shifting using the attentional set-shifting task (ASST). However, this rodent paradigm distinguishes between several types of cognitive rigidity associated with neuropsychiatric conditions. The goal of this study was to test 5-HT7 receptor involvement in the reversal learning component of the ASST because this ability depends primarily on the orbito-frontal cortex, which shows strong 5-HT7 receptor expression. We found that impaired performance on the ASST induced by NMDA receptor blockade (MK-801, 0.2 mg/kg) in 14 rats was reversed by coadministration of the 5-HT7 receptor antagonist SB-269970. The strongest effect was found on the reversal phases of ASST, whereas injection of SB-269970 alone had no effect. These results indicate that 5-HT7 receptor mechanisms may have a specific contribution to the complex cognitive deficits, increasing perseverative responding, in psychiatric diseases, including schizophrenia, depression, and anorexia nervosa, which express different forms of cognitive inflexibility.

Oral Bioavailability Enhancement of Amisulpride: Complexation and its Pharmacokinetics and Pharmacodynamics Evaluations

BACKGROUND

Many CNS drugs have low bioavailability due to their poor water solubility of extensive first-pass metabolism and hence have less effectiveness.

OBJECTIVE

The present study aims to enhance the solubility and oral bioavailability of poorly watersoluble antipsychotic drug Amisulpride (AMS) through complexation with 2-hydroxypropyl β- cyclodextrin (HPβCD). It has slow and erratic absorption after oral administration.

METHODS

This report describes the study of the phase solubility diagram, preparation of the inclusion complex and tablet of prepared inclusion complex, characterization of the physico-chemical properties of the inclusion complex and tablet.

RESULTS

In-vitro study (100 % drug release in 15 minutes), and in-vivo study of an AL-type (linear type) phase solubility diagram indicated a complex of AMS-HP-β-CD with the constant complex formation of 13245 M-1 at 37°C. The complex formation was confirmed by DSC, IR, and X-ray diffraction. The extent of absorption of the complex was determined in rats and was compared with that of pure drug and the market product. The peak plasma concentration of pure drug was 30.05 ± 1.3 ng/ml (Cmax) at 60 ± 3 min, whereas with the market product the value was 54.85 ± 1.2 ng/ml at 40 ± 1 min and with AMS-HPβCD inclusion complex the value was 79.01 ± 1.5 ng/ml. The AUCtot of the pure drug was 2980.34±3.6, the market product was 7238.73±2.9 and of the inclusion complex was 11871.1±2.8.

CONCLUSION

Pharmacodynamic studies in mice showed improved effectiveness of drug compared to pure drug. The oral bioavailability of AMS was improved from 48% to 78%.

Conjugation of Amisulpride, an Anti-Psychotic Agent, with 5-Aminosalicylic Acid via an Azo Bond Yields an Orally Active Mutual Prodrug against Rat Colitis

Amisulpride (ASP), an anti-psychotic agent, is a pharmacologically equivalent to sulpiride (SP). Because SP demonstrates anti-ulcer and anti-colitic activities, ASP with an aniline moiety was azo-coupled to salicylic acid to generate 5-(aminoethanoylsulfamoyl)-N-[(1-ethylpyrrolidin-2-yl)methyl]-2-methoxybenzamide (ASP-azo-ASA), with the expectation that it would act as a colon-specific mutual prodrug against colitis. Following a 24 h incubation, approximately 80% of ASP-azo-ASA was cleaved to form ASP and 5-aminosalicylic acid (5-ASA) in the cecal contents, whereas it remained stable in the small intestinal contents. Oral gavage of ASP-azo-ASA (oral ASP-azo-ASA) delivered 5-ASA to the cecum to levels comparable with those observed for sulfasalazine (SSZ; clinical colon-specific prodrug of 5-ASA) and without detectable concentrations of ASP in the blood, indicating efficient colonic delivery. Oral ASP-azo-ASA ameliorated 2, 4-dinitrobenzenesulfonic acid hydrate (DNBS)-induced colitis in rats more effectively than oral SSZ. Additionally, oral ASP-azo-ASA lowered the levels of inflammatory mediators in the inflamed distal colon more effectively than oral SSZ. Combined treatment with 5-ASA and ASP via the rectal route more effectively reversed colonic damage and inflammation than treatment with 5-ASA or ASP alone, confirming the mutual anti-colitic actions of 5-ASA and ASP. In conclusion, ASP-azo-ASA is an orally active mutual prodrug against rat colitis with limited systemic absorption of ASP.

Escitalopram-induced liver injury: A case report and review of literature

BACKGROUND

Depression is a growing public health problem that affects over 350 million people globally and accounts for approximately 7.5% of healthy years lost due to disability. Escitalopram, one of the first-line medications for the treatment of depression, is a selective serotonin reuptake inhibitor and one of the most commonly prescribed antidepressant medications worldwide. Although thought to be generally safe and with minimal drug-drug interactions, we herein present an unusual case of cholestatic liver injury, likely secondary to escitalopram initiation.

CASE SUMMARY

A 56-year-old Chinese lady presented with fever and cholestatic liver injury two weeks after initiation of escitalopram for the treatment of psychotic depression. Physical examination was unremarkable. Further investigations, including a computed tomography scan of the abdomen and pelvis and tests for hepatitis A, B and C and for autoimmune liver disease were unyielding. Hence, a diagnosis of escitalopram-induced liver injury was made. Upon stopping escitalopram, repeat liver function tests showed downtrending liver enzymes with eventual normalization of serum aspartate aminotransferase and alanine aminotransferase one-week post-discharge.

CONCLUSION

Clinicians should be aware of the possibility of escitalopram-induced liver injury when initiating depressed patients on antidepressant treatment. This requires extra vigilance as most patients may remain asymptomatic. Measurement of liver function tests could be considered after initiation of antidepressant treatment, especially in patients with pre-existing liver disease.

Impaired Gastric Hormone Regulation of Osteoblasts and Lysyl Oxidase Drives Bone Disease in Diabetes Mellitus

Diabetic bone disease is a complication of type I and type II diabetes, both of which are increasing in the United States and elsewhere. Increased hip and foot fracture rates do not correlate well with changes in bone mineral density (BMD), whereas studies support the importance of collagen structure to bone strength. Extracellular lysyl oxidase (LOX) catalyzes the oxidative deamination of hydroxylysine and lysine residues in collagens resulting in aldehydes that subsequently form critically important biosynthetic crosslinks that stabilize functional collagens. Although LOX-dependent biosynthetic crosslinks in bone collagen are deficient in diabetic bone, the expression and regulation of bone LOXs in diabetes have not been comprehensively studied. Here, we found that LOX is profoundly downregulated in bone in diabetes. Moreover, we have identified a novel metabolic regulatory relationship that is dysregulated in diabetes using mouse models. Data indicate that the incretin (gastric hormone) known as glucose-dependent insulinotropic polypeptide (GIP) that is anabolic to osteoblasts strongly upregulates LOX, and that this regulation is disrupted in the streptozotocin-induced model of diabetes in mice. In vivo and in vitro studies support that diabetes results in elevated circulating peripheral dopamine, likely also derived from the gut, and is responsible for blocking GIP signaling and LOX levels in osteoblasts. Moreover, peripheral administration of the dopamine D2 receptor antagonist amisulpride to diabetic mice restored trabecular bone structure to near normal and partially reversed downregulation of LOX. Taken together our data identifies a novel metabolic relationship between the gut-derived hormone GIP and bone-derived LOX, and points to the importance of LOX dysregulation in the pathology of diabetic bone disease. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

An update of safety of clinically used atypical antipsychotics

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Clinical Assessment of Weight Gain with Atypical Antipsychotics - Blonanserin vs Amisulpride

BACKGROUND

Atypical antipsychotics appear to have the greatest potential to induce weight gain. Antipsychotic-induced weight gain is the one of main cause of non-compliance and discontinuation of treatment, often resulting in the relapse of psychosis.

OBJECTIVE

To compare the weight gain between amisulpride and blonanserin treatment, in persons with psychosis.

MATERIALS AND METHODS

Fifty six subjects with psychosis attending psychiatry department at KR Hospital, Mysore were randomized into two equal groups. After obtaining informed consent, subjects of group I received amisulpride tablets 200 mg BD, and group II received blonanserin tablets 4 mg BD, for eight weeks. Body weight, Body Mass Index (BMI) and Waist Hip Ratio (WHR) were measured at baseline, 4 weeks and 8 weeks.

RESULTS

The mean weight gain with amisulpride at 4 weeks was 2.73 kg (5.21%) and at 8 weeks was 4.34 kg (8.28%) from the baseline. The mean weight gain with blonanserin at 4 weeks was 1.77 kg (3.46%) and at 8 weeks was 3.46 kg (6.75%) from the baseline. The mean BMI increase at 8 weeks with amisulpride was 1.66 ± 0.56 and with blonanserin was 1.34 ± 0.77. The mean WHR increase at 8 weeks with amisulpride was 0.036 ± 0.026 and with blonanserin was 0.029 ± 0.020. There was statistically significant increase in weight, BMI and WHR associated with both blonanserin and amisulpride at 8 weeks. But there was no statistically significant difference in those parameters between blonanserin and amisulpride, at eight weeks.

CONCLUSION

Even though there was no significant difference in the weight gain caused by blonanserin, in comparison with amisulpride, both these drugs individually caused significant weight gain at 8 weeks, which is in contrast with the earlier studies, which needs to be further evaluated.

Dopamine D2-receptor blockade enhances decoding of prefrontal signals in humans

The prefrontal cortex houses representations critical for ongoing and future behavior expressed in the form of patterns of neural activity. Dopamine has long been suggested to play a key role in the integrity of such representations, with D2-receptor activation rendering them flexible but weak. However, it is currently unknown whether and how D2-receptor activation affects prefrontal representations in humans. In the current study, we use dopamine receptor-specific pharmacology and multivoxel pattern-based functional magnetic resonance imaging to test the hypothesis that blocking D2-receptor activation enhances prefrontal representations. Human subjects performed a simple reward prediction task after double-blind and placebo controlled administration of the D2-receptor antagonist amisulpride. Using a whole-brain searchlight decoding approach we show that D2-receptor blockade enhances decoding of reward signals in the medial orbitofrontal cortex. Examination of activity patterns suggests that amisulpride increases the separation of activity patterns related to reward versus no reward. Moreover, consistent with the cortical distribution of D2 receptors, post hoc analyses showed enhanced decoding of motor signals in motor cortex, but not of visual signals in visual cortex. These results suggest that D2-receptor blockade enhances content-specific representations in frontal cortex, presumably by a dopamine-mediated increase in pattern separation. These findings are in line with a dual-state model of prefrontal dopamine, and provide new insights into the potential mechanism of action of dopaminergic drugs.

α2-Adrenoceptors in the treatment of major neuropsychiatric disorders

Presynaptic autoreceptors mediate a retrograde transfer of information by a negative feedback mechanism mediated by the transmitter of the neuron, and fulfill an autoregulatory function in neurotransmission in the peripheral and central nervous system (CNS). Starting with norepinephrine (NE), it was later reported that an autoreceptor-mediated negative feedback mechanism exists for other neurotransmitters, including dopamine (DA), serotonin, acetylcholine, histamine, GABA, and glutamate. This feedback mechanism regulates calcium-dependent transmitter release and synthesis through terminal presynaptic autoreceptors, while the firing rate of the neuron is regulated through somatodendritic autoreceptors.

A validated GC/MS method for the determination of amisulpride in whole blood

A sensitive GC/MS method for the determination of amisulpride in whole blood was developed, optimized and validated. Sample preparation included solid-phase extraction using HF Bond Elut C18 cartridges and further derivatization with heptafluorobutyric anhydride (HFBA). The limits of detection and quantification were 3.00 and 10.0 μg/L, respectively. The calibration curves were linear up to 1000 μg/L (R(2)≥0.991). Absolute recovery ranged from 94.2 to 101%. Accuracy was found to be between -8.7 and 1.9% and imprecision was less than 10.0%. The developed method covers the generally accepted therapeutic range but it can also cover levels above them. This makes our method suitable for the determination of amisulpride not only for clinical purposes on psychiatric patients, but also during the investigation of forensic cases where amisulpride is involved.

Effects of risperidone, amisulpride and nicotine on eye movement control and their modulation by schizotypy

RATIONALE

The increasing demand to develop more efficient compounds to treat cognitive impairments in schizophrenia has led to the development of experimental model systems. One such model system combines the study of surrogate populations expressing high levels of schizotypy with oculomotor biomarkers.

OBJECTIVES

We aimed (1) to replicate oculomotor deficits in a psychometric schizotypy sample and (2) to investigate whether the expected deficits can be remedied by compounds shown to ameliorate impairments in schizophrenia.

METHODS

In this randomized double-blind, placebo-controlled study 233 healthy participants performed prosaccade (PS), antisaccade (AS) and smooth pursuit eye movement (SPEM) tasks after being randomly assigned to one of four drug groups (nicotine, risperidone, amisulpride, placebo). Participants were classified into medium- and high-schizotypy groups based on their scores on the Schizotypal Personality Questionnaire (SPQ, Raine (Schizophr Bull 17:555-564, 1991)).

RESULTS

AS error rate showed a main effect of Drug (p < 0.01), with nicotine improving performance, and a Drug by Schizotypy interaction (p = 0.04), indicating higher error rates in medium schizotypes (p = 0.01) but not high schizotypes under risperidone compared to placebo. High schizotypes had higher error rates than medium schizotypes under placebo (p = 0.03). There was a main effect of Drug for saccadic peak velocity and SPEM velocity gain (both p ≤ 0.01) indicating impaired performance with risperidone.

CONCLUSIONS

We replicate the observation of AS impairments in high schizotypy under placebo and show that nicotine enhances performance irrespective of group status. Caution should be exerted in applying this model as no beneficial effects of antipsychotics were seen in high schizotypes.

Interactions between antiepileptics and second-generation antipsychotics

INTRODUCTION

Pharmacokinetic and pharmacodynamic drug interactions (DIs) can occur between antiepileptics (AEDs) and second-generation antipsychotics (SGAPs). Some AED and SGAP pharmacodynamic mechanisms are poorly understood. AED-SGAP combinations are used for treating comorbid illnesses or increasing efficacy, particularly in bipolar disorder.

AREAS COVERED

This article provides a comprehensive review of the interactions between antiepileptics and second-generation antipsychotics. The authors cover pharmacokinetic AED-SGAP DI studies, the newest drug pharmacokinetics in addition to the limited pharmacodynamic DI studies.

EXPERT OPINION

Dosing correction factors and measuring SGAP levels can help to compensate for the inductive properties of carbamazepine, phenytoin, phenobarbital and primidone. Further studies are needed to establish the clinical relevance of combining: i) AED strong inducers with amisulpride, asenapine, iloperidone, lurasidone and paliperidone; ii) valproate with aripiprazole, asenapine, clozapine and olanzapine; iii) high doses of oxcarbazepine (≥ 1500 mg/day) or topiramate (≥ 400 mg/day) with aripiprazole, lurasidone, quetiapine, risperidone, asenapine and olanzapine. Two pharmacodynamic DIs are beneficial: i) valproate-SGAP combinations may have additive effects in bipolar disorder, ii) combining topiramate or zonisamide with SGAPs may decrease weight gain. Three pharmacodynamic DIs contributing to decreased safety are common: sedation, weight gain and swallowing disturbances. A few AED-SGAP combinations may increase risk for osteoporosis or nausea. Three potentially lethal but rare pharmacodynamic DIs include pancreatitis, agranulocytosis/leukopenia and heat stroke. The authors believe that collaboration is needed from drug agencies and pharmaceutical companies, the clinicians using these combinations, researchers with expertise in meta-analyses, grant agencies, pharmacoepidemiologists and DI pharmacologists for future progression in this field.

Effects on prolongation of Bazett's corrected QT interval of seven second-generation antipsychotics in the treatment of schizophrenia: a meta-analysis

The use of second-generation antipsychotics (SGAs) for the treatment of schizophrenia has surged worldwide. Amisulpride, aripiprazole, olanzapine, quetiapine, risperidone, sertindole and ziprasidone have now been commonly prescribed. Their effects on QT interval differ but evidence remains sparse and mostly inconclusive. Since prolongation of heart-rate corrected QT interval has been implicated as an useful surrogate marker to predict drug-related cardiac mortality and pro-arrhythmic potentials, it is timely and necessary to compare the effects of Bazett's corrected QT interval (QT(Bc)) prolongation for the commonly prescribed SGAs. A meta-analysis was conducted according to suggestions by the Quality of Reporting of Meta-analysis group with literature identified using various databases and augmented with hand-searching to assess the magnitude and risk on QT(Bc) prolongation by these seven SGAs for treatments in adult subjects with schizophrenia. Because of incomplete QT(Bc) data reporting, quetiapine could not be assessed by the meta-analytical approach in this study. Aripiprazole was the only SGA associated with both statistically significant lower risk and mean change in QT(Bc), with sertindole giving a statistically significant worsening effect on mean QT(Bc). Other analyses did not demonstrate any statistically significant pooled effects for the studied SGAs, neither on the magnitude over mean or mean change, nor the risk on QT(Bc) prolongation.

Neuroleptic malignant syndrome associated with atypical antipsychotic drugs

Neuroleptic malignant syndrome (NMS) is a rare but potentially severe idiosyncratic adverse reaction usually seen in the context of treatment with antipsychotic drugs. Although NMS is historically associated with the classic or 'typical' antipsychotic drugs, it is also a potential adverse effect of atypical antipsychotic drugs. The widespread use of atypical antipsychotic drugs highlights the need to examine the data relating to the symptomatology, diagnosis, classification and management of NMS with these newer agents. We used MEDLINE and EMBASE to identify NMS case reports and systematic reviews published to June 2008 related to the atypical antipsychotic drugs clozapine, olanzapine, risperidone, paliperidone, aripiprazole, ziprasidone, amisulpride and quetiapine. Case reports and reviews were systematically examined. Our review suggests that, in general, NMS associated with atypical antipsychotic drugs manifests in a typical manner. One notable exception is clozapine-induced NMS, which appears less likely to manifest with extrapyramidal features, including rigidity and tremor. The available literature highlights the divergence of opinion relating to the core diagnostic features of NMS and its conceptualization as a categorical versus dimensional disorder. Both these issues have relevance for the identification of atypical or milder forms of NMS, which are sometimes seen with atypical antipsychotic drugs.

Update on the management of symptoms in schizophrenia: focus on amisulpride

Amisulpride is an atypical antipsychotic drug with a unique receptor pharmacology which is dose dependent. It is a standard treatment in dysthymia as well as in psychosis. Amisulpride is efficacious, effective and well tolerated in positive symptoms of schizophrenia: there is extensive evidence that it treats negative symptoms when given in low doses, although relative lack of EPS and an antidepressant effect may contribute. In first-episode patients amisulpride is an option, although there is little comparative work available. Amisulpride has the best evidence as an effective adjunct to clozapine treatment. Regarding intellectual function, amisulpride appears cognitive sparing but the clinical relevance of this remains obscure. There is evidence that amisulpride can improve social function but again there is little comparative work to demonstrate any particular advantages. Regarding the current conventional versus atypical antipsychotic controversy, amisulpride did better in switching studies and meta-analyses than in the single large pragmatic randomized trial reported to date. It is a versatile drug, and may offer advantages over other atypical antipsychotic drugs in the treatment of negative and depressive symptoms, and tolerability advantages such as the avoidance of weight gain. Essentially it rests with the treating clinician to employ a rational psychopharmacological approach towards the individual patient: there will be few circumstances in which amisulpride will not be a likely contender as a treatment choice.

Antipsychotics possessing antidepressive efficacy increase Golf protein in rat striatum

INTRODUCTION

Recently, second-generation antipsychotics (SGAs) have been widely used in the treatment of mood disorders. However, the mechanisms of the antidepressant effect of SGAs remain unclear. We proposed that Golf protein, a stimulant alpha-subunit of G protein coupled with the dopamine D1 receptor, might a play the key role in the antidepressive effect of antidepressants. To clarify the relationship between Golf protein and the antidepressive effects of antipsychotics, we examined the effects of chronic treatment with several antipsychotics on the level of Golf protein in the rat striatum.

MATERIALS AND METHODS

Male Wistar rats were treated with one of several antipsychotics for 2 weeks: olanzapine (2, 5, or 10 mg/kg), sulpiride (5, 10, or 50 mg/kg), amisulpride (3, 10, or 20 mg/kg), risperidone (0.2 or 2 mg/kg), haloperidol (0.3 or 3 mg/kg), or clozapine (2 or 10 mg/kg).

RESULTS AND DISCUSSION

Olanzapine (5 mg/kg), sulpiride (5, or 10 mg/kg), and amisulpride (10 mg/kg) treatments significantly increased the level of Golf protein, but there was no increase with administration of higher doses of these three antipsychotics. Risperidone, haloperidol, and clozapine treatment did not change the level of Golf protein at any dose. In this study, all antipsychotics that have antidepressive effects increased Golf protein. This suggests that an increase in Golf may play an important role in the antidepressive effect of antipsychotics.

CONCLUSION

We postulate that the increase in Golf protein levels result in an increase the proportion of D1 receptors in the high-affinity state and that augmentation of the dopaminergic system exerts the antidepressant effect.

Practical issues with amisulpride in the management of patients with schizophrenia

Amisulpride is an atypical antipsychotic with a significantly greater effect size than first-generation, typical antipsychotics, and efficacy at least similar to that of olanzapine and risperidone in large-scale clinical trials in schizophrenia. Amisulpride provides greater improvement in positive and negative symptoms of schizophrenia, a better long-term outcome than typical antipsychotics, and distinct tolerability advantages over typical antipsychotics, which are reported to cause extrapyramidal symptoms (EPS) in 20-50% of patients. In addition, amisulpride is associated with significantly less weight gain than olanzapine and risperidone, does not increase body mass index, and favourably influences lipid profiles. In many patients with schizophrenia, adverse events impair adherence to treatment, and switching from typical or atypical antipsychotic therapy to amisulpride may be clinically appropriate. Observational drug-utilization studies suggest that many physicians switch to amisulpride because of fewer EPS and/or less weight gain and improved patient adherence. Cross-tapering (over 4 weeks), rather than abrupt cessation of pre-switch treatment, is preferred. Amisulpride has a low risk of drug-drug interactions, and, during cross-tapering, patients can remain on concurrent treatments (e.g. anticholinergics and antiparkinsonian agents) until the effective dosage has been reached. An appropriate amisulpride starting dose is 800 mg/day for patients with acute psychotic exacerbations, 400-800 mg/day for patients with predominantly positive symptoms, and 100-300 mg/day for predominantly negative symptoms. Amisulpride may be particularly suitable for clozapine-augmentation therapy in patients with refractory schizophrenia. Indeed, amisulpride is more effective than quetiapine as augmentation therapy in patients partially responsive to clozapine, and several prospective open-label studies and case series have reported promising results for amisulpride/clozapine combination therapy. In three prospective studies, addition of amisulpride 200-800 mg/day to clozapine significantly reduced mean scores on the Brief Psychiatric Rating Scale (BPRS) total (-33% to -35%), Clinical Global Impression (CGI)-Severity scale (-31%), Positive and Negative Syndrome Scale total (-22%), and Scale for the Assessment of Negative Symptoms (-34%). The proportion of responders (CGI score > or =3 or BPRS improvement >20%) was 71-86%. Retrospective case-series analyses have also reported improved psychopathological state, reduced adverse events, and lower clozapine dosage requirement with use of this combination. The pharmacological and clinical profiles of amisulpride suggest that this agent is a viable clinical option when a change of antipsychotic therapy is required in patients with schizophrenia because of lack of efficacy, adverse events and poor adherence to treatment, or for augmentation of clozapine in treatment-resistant illness.

Improvement of patient compliance after switching from conventional neuroleptics to the atypical neuroleptic amisulpride

Medication noncompliance of schizophrenic outpatients is an important problem in clinical practice, causing relapse and illness deterioration. Because atypical neuroleptics have, in controlled clinical studies, been shown to be better tolerated and accepted by patients, the question is whether switching from conventional to atypical neuroleptics such as amisulpride can increase patient compliance also under conditions of routine care. In a drug utilization observation study 570 schizophrenic outpatients, who had been pretreated with conventional neuroleptics and then been switched for individual clinical reasons to amisulpride, were observed for 3 months. Sociodemographic, illness and treatment related variables (e.g. Positive and Negative Symptom Scale, side effects), patients' subjective attitudes, and premedication and treatment compliance were assessed using standardized instruments. A total of 43.7% were rated as being noncompliant with the premedication, while 85.8% were rated as compliant after being switched to amisulpride, including 82.7% of the former noncompliant patients. Patients who had become compliant showed a signicantly better psychopathological status after 3 months as compared to still noncompliant patients, including a lower rate of inpatient stays. Switching noncompliant patients from conventional to atypical neuroleptics like amisulpride can improve patient compliance and psychopathology under conditions of routine treatment.

Comparison of pramipexole and amisulpride on alertness, autonomic and endocrine functions in healthy volunteers

RATIONALE

In a previous study in healthy volunteers, the anti-Parkinsonian drug pramipexole caused sedation and pupil dilatation, consistent with the stimulation of inhibitory D(2)/D(3) autoreceptors on the ventral tegmental area dopaminergic neurones. The sedation may be related to the removal of the dopaminergic excitation of the locus coeruleus (via the meso-coerulear pathway), whereas the pupil dilatation may be due to the removal of the dopaminergic excitation of the Edinger-Westphal nucleus (via a putative meso-pupillomotor pathway).

OBJECTIVES

We investigated the hypothesis that amisulpride, a D(2)/D(3) receptor antagonist, would have effects opposite to those of pramipexole on alertness, pupillary and endocrine functions.

MATERIALS AND METHODS

Pramipexole (0.5 mg), amisulpride (50 mg), and their combination were administered to 16 healthy males in a balanced, cross-over, double-blind design. Tests included measures of alertness (Pupillographic Sleepiness Test, critical flicker fusion frequency, visual analogue scales), pupillary functions (resting pupil diameter, light and darkness reflex responses), non-pupillary autonomic functions (heart rate, blood pressure, salivation, core temperature), and endocrine functions [blood concentrations of prolactin, growth hormone (GH) and thyroid stimulating hormone (TSH)]. Data were analysed by ANOVA.

RESULTS

Pramipexole reduced alertness and pupillary light reflex response amplitude, tended to reduce core temperature, reduced prolactin levels and increased GH levels. Amisulpride reduced pupil diameter, increased the amplitude of the light reflex response and prolactin and TSH levels.

CONCLUSIONS

The opposite effects of pramipexole and amisulpride on alertness, pupillary function and pituitary hormone levels are consistent with their interactions with inhibitory D(2)/D(3) receptors on VTA neurones and in the tuberoinfundibular system.

Amisulpride in the treatment of behavioural disturbances among patients with moderate to severe Alzheimer's disease

OBJECTIVE

The aim of this article was to evaluate the effects of amisulpride on the behavioural and psychiatric symptoms of patients with Alzheimer's disease (AD).

MATERIALS AND METHODS

In this open-label study, we observed 18 outpatients affected by moderate to severe AD, complicated with agitation and disruptive behaviours. Behavioural, cognitive and motor effects of amisulpride at baseline and after 12 weeks were rated by the Neuropsychiatric Inventory (NPI), Mini Mental State Examination, Clinical Dementia Rating Scale, activities of daily living, and the motor score of the Unified Parkinson's Disease Rating Scale.

RESULTS

After treatment with amisulpride (200 mg/day), the patients showed a significant decrease in NPI total scores, particularly for the subitem 'agitation'. Cognitive and motor variables did not worsen significantly over the 12-week period.

CONCLUSIONS

This preliminary observation suggests that amisulpride can be useful to control agitation and disruptive behaviours in AD patients without significantly effecting vigilance and motor activity.

Ziprasidone and amisulpride effectively treat negative symptoms of schizophrenia: results of a 12-week, double-blind study

We compared the efficacy of ziprasidone and amisulpride in the treatment of negative symptoms and overall psychopathology in subjects who had chronic schizophrenia with predominantly negative symptoms. This multicentre, 12-week, double-blind study randomly assigned subjects with predominantly negative-symptom schizophrenia [i.e. Positive and Negative Syndrome Scale (PANSS) Negative Subscale score >or=6 points greater than Positive Subscale score] to ziprasidone (40-80 mg b.i.d.; n=60) or amisulpride (50-100 mg b.i.d.; n=63). The primary efficacy variable was the change from baseline in PANSS Negative Subscale score. Secondary efficacy variables included change in scores for PANSS Total, Global Assessment of Functioning, Brief Psychiatric Rating Scale derived from PANSS Total and Core, Clinical Global Impression (CGI)-Severity and CGI-Improvement. For the change in PANSS Negative Subscale score, a ratio to assess the equivalence of the treatment groups was calculated from the least squares mean changes from baseline, with equivalence claimed if the lower limit of the 95% confidence interval of the ratio exceeded 0.60. Mean daily dose, adjusted for differential numbers of subjects and differential days between visits, was 118.0 mg for ziprasidone and 144.7 mg for amisulpride. Mean PANSS Negative Subscale scores improved over the 12-week treatment period for intent-to-treat subjects, evaluable subjects (subjects with >or=4 weeks of double-blind treatment and no protocol deviations) and completers in both treatment groups. Ziprasidone demonstrated efficacy comparable to amisulpride in improving negative symptoms and global psychopathology. The groups demonstrated comparable improvements in secondary efficacy variables. Both agents were generally well tolerated, with comparably low incidences of movement disorders. In subjects with negative symptom-prominent schizophrenia, ziprasidone in mean daily doses of 118 mg was equivalent to amisulpride in mean daily doses of 148 mg in ameliorating negative symptoms and comparable in improving overall psychopathology and global illness severity.

Antipsychotic and antidepressive effects of second generation antipsychotics: two different pharmacological mechanisms?

Second generation antipsychotics display antidepressive effects in schizophrenic patients that are more pronounced than those of traditional neuroleptics and that go beyond antidepressive effects secondary to the reduction of positive symptoms. The antidepressive potential of second generation antipsychotics is presumably related to their pharmacological mechanisms, which differ from those of traditional neuroleptics. Among others, 5-HT(2A) antagonism is of special relevance for most of the new antipsychotics in this respect. But also special interactions with the dopaminergic system, as is the case with amisulpride and aripiprazole, or noradrenalin- and/or serotonin-reuptake-inhibition, as with ziprasidone and zotepine, should be considered. It can be summarised that the antipsychotic and antidepressive effects of second generation antipsychotics are mostly based on different pharmacological mechanisms. This might be especially true for direct antidepressive effects, i. e. antidepressive effects that are not mediated by the reduction of positive symptoms.

Aripiprazole: a novel atypical antipsychotic drug with a uniquely robust pharmacology

Aripiprazole (Abilify) is an atypical antipsychotic drug that has been recently introduced for clinical use in the treatment of schizophrenia. Aripiprazole has a unique pharmacologic profile that includes partial agonism at several G-protein coupled receptors (GPCRs) [especially dopamine (D2) and 5-HT1A] and antagonistic action at others (especially 5-HT2A). Clinical trials indicate that aripiprazole is effective in treating the positive and negative symptoms of schizophrenia. In short-term studies rapid onset of action (within one week) has been demonstrated. Preliminary data indicate that aripiprazole may also be effective in the treatment of manic symptoms of bipolar disorder. At recommended doses, aripiprazole appears to be safe and well tolerated in most adult patients with schizophrenia and schizoaffective disorder. There is only limited information available on the use of aripiprazole in children and adolescents, and pilot data suggest that a revised dosing strategy, based on weight, is indicated in this population. In the long-term studies, the use of aripiprazole was associated with continued efficacy, good compliance and increased time-to-relapse. Aripiprazole represents the first functionally selective atypical antipsychotic drug.

Amisulpride: a review of its use in the management of schizophrenia

Amisulpride (Solian), a substituted benzamide derivative, is a second-generation antipsychotic that preferentially binds to dopamine D2/D3 receptors in limbic rather than striatal structures. High dosages preferentially antagonise postsynaptic D2/D3 receptors, resulting in reduced dopamine transmission, and low dosages preferentially block presynaptic D2/D3 receptors, resulting in enhanced dopamine transmission. Amisulpride (200-1200 mg/day) was at least as effective as haloperidol and as effective as risperidone or olanzapine, in studies of up to 1 year in patients with schizophrenia manifesting predominantly positive symptoms. Amisulpride (50-300 mg/day) was significantly more effective than placebo in studies of up to 6 months in patients manifesting predominantly negative symptoms. Quality of life was also improved significantly more in patients receiving amisulpride than in those receiving haloperidol in 4- and 12-month studies in patients with predominantly mixed symptoms. Amisulpride was generally well tolerated in clinical trials. In patients with predominantly positive symptoms, amisulpride appeared to be better tolerated than haloperidol and was tolerated as well as risperidone and olanzapine. The incidence of extrapyramidal adverse effects with amisulpride was lower than with haloperidol but was generally similar to risperidone or olanzapine. Weight gain with amisulpride was less than that with risperidone or olanzapine and, unlike these agents, amisulpride does not seem to be associated with diabetogenic effects. Plasma prolactin levels are increased during amisulpride therapy and amenorrhoea occurs in about 4% of women. The incidence of adverse events with low dosages of amisulpride (< or = 300 mg/day) in patients with predominantly negative symptoms was similar to that observed with placebo. In conclusion, oral amisulpride (200-1200 mg/day) is at least as effective as haloperidol, and as effective as risperidone or olanzapine, in the treatment of patients with schizophrenia manifesting predominantly positive symptoms. In the treatment of patients manifesting predominantly negative symptoms, low dosages of amisulpride (50-300 mg/day) are significantly more effective than placebo. Amisulpride appears to be better tolerated than haloperidol, causing a lower incidence of extrapyramidal adverse effects and an improved quality of life. Compared with risperidone or olanzapine, amisulpride is more likely to cause hyperprolactinaemia, but has a lower propensity to cause weight gain and does not seem to be associated with diabetogenic effects. Thus, amisulpride is an effective and well tolerated option for the first-line treatment of patients with acute schizophrenia as well as for those requiring long-term maintenance therapy.

Therapeutic monitoring of new antipsychotic drugs

Typical antipsychotic drugs qualify for therapeutic drug monitoring (TDM) primarily for the following reasons: control of compliance and avoidance of extrapyramidal side effects by keeping chronic exposure to minimal effective blood levels. For the atypical antipsychotic clozapine, drug safety is another reason to use TDM. With regard to the new antipsychotics risperidone, olanzapine, quetiapine, amisulpride, ziprasidone, and aripiprazole, which have been introduced in the clinic during the last few years, the rationale to use TDM is a matter of debate. Positron emission tomography (PET), which enables measurement of the occupancy of dopamine D2 receptors, revealed that receptor occupancy correlated better with plasma concentrations than with doses of the antipsychotics. Regarding plasma levels related to therapeutic effects, optimal concentrations have been established for clozapine (350-600 ng/mL), risperidone (20-60 ng/mL), and olanzapine (20-80 ng/mL) but not for the other new antipsychotics. Studies that included analyses of drug levels in blood reported mean concentrations of 68 ng/mL for quetiapine and 317 ng/mL for amisulpride under therapeutic doses of the antipsychotic drugs. For ziprasidone or aripriprazole, data on therapeutic drug concentrations are so far lacking. In conclusion, evidence is growing that TDM may improve efficacy and safety in patients treated with the new antipsychotic drugs, especially when patients do not respond or develop side effects under therapeutic doses. The few reported investigations, however, need to be confirmed and extended.

Treatment of the metabolic disturbances caused by antipsychotic drugs: focus on potential drug interactions

The risk of excessive bodyweight gain, glucose dysregulation and hyperlipidaemia is differentially increased by conventional and atypical antipsychotic drugs. Switching or combining agents may be sufficient in some cases, but in many instances additional drug treatment will be required. This includes oral antidiabetics, insulin and agents to treat hyperlipidaemia, hypertension and platelet dysfunction, among others. Numerous pharmacokinetic and pharmacodynamic interactions with the antipsychotics are possible, although few have been tested in formal studies. After reviewing the literature, the authors provide preliminary guidelines to assist clinicians in drug selection for this complex and fragile clinical population.

Amisulpride: limbic specificity and the mechanism of antipsychotic atypicality

Amisulpride clearly has the clinical profile of an atypical antipsychotic, characterised in particular by its lower propensity to induce extrapyramidal side effects as well as its greater efficacy in treating negative symptoms compared with classical neuroleptics. In addition to the clinical advantages over classical neuroleptics, it has also been demonstrated that the clinical profile of amisulpride is comparable to that of other modern atypical neuroleptics. Animal data also allow the conclusion to be drawn that amisulpride has an atypical profile. For example, amisulpride does not provoke catalepsy which is characteristic of postsynaptic D2 blockade in the rat. The induction of catalepsy in animal models is usually seen as an indicator of the propensity to induce extrapyramidal side effects in patients. In relation to the widely accepted hypothesis that the inclusion of 5-HT2A antagonism in addition to D2 antagonism is of great relevance for the atypicality of an antipsychotic, and given the fact that amisulpride lacks 5-HT2A antagonism, the pharmacological explanation of the clinically well-proven atypicality of amisulpride is of great interest. Based on basic research and in vivo imaging studies, two mechanisms in particular seem to explain the atypicality of amisulpride: preferential action on limbic D2/D3 receptors and preferential blockade of presynaptic D2/D3 receptors. In addition, the fast dissociation hypothesis can contribute to the explanation of the atypical clinical profile of amisulpride. The relevance of the D3 blockade in the context of atypicality is not yet completely clear.

Generalization of clozapine as compared to other antipsychotic agents to a discriminative stimulus elicited by the serotonin (5-HT)2A antagonist, MDL100,907

Employing a two-lever, food-reinforced FR10 procedure, rats were trained to recognize a discriminative stimulus (DS) elicited by the 5-HT(2A) receptor antagonist and potential antipsychotic agent, MDL100,907 (0.16 mg/kg, i.p.). In generalization tests, by analogy to MDL100,907 itself (Effective Dose(50) (ED(50)), 0.002 mg/kg, s.c.), the 'atypical' antipsychotic, clozapine, which displays high affinity for 5-HT(2A) as compared to D(2) receptors, dose-dependently and fully generalized to MDL100,907 (ED(50), 0.2 mg/kg, s.c.). S16924 (0.05 mg/kg, s.c.), S18327 (0.09 mg/kg, s.c.), quetiapine (1.8 mg/kg, s.c.), risperidone (0.02 mg/kg, s.c.) and ziprasidone (0.01 mg/kg, s.c.), antipsychotics which possess-like clozapine-marked affinity for 5-HT(2A) versus D(2) receptors, also generalized to MDL100,907. In distinction, raclopride, an antipsychotic which selectively interacts with D(2) versus 5-HT(2A) receptors, did not display significant generalization. Interestingly, haloperidol, which shows only modest affinity for 5-HT(2A) versus D(2) sites, generalized to MDL100,907 (ED(50), 0.02 mg/kg, s.c.). In light of the antagonist properties of haloperidol, clozapine and all other antipsychotics tested (except raclopride) at alpha(1)-adrenoceptors (ARs), the selective alpha(1)-AR antagonists, prazosin and WB4101, were examined. Both dose-dependently and fully generalized to MDL100,907 (ED(50)s, 0.07 and 0.11 mg/kg, s.c., respectively). At doses showing pronounced generalization to MDL100,907, the only drugs which significantly suppressed response rates were haloperidol and, weakly, quetiapine. Raclopride also markedly decreased response rates. In conclusion, the antipsychotic agents, clozapine, ziprasidone, risperidone, S16924, S18327, quetiapine and haloperidol, all generalized to a DS elicited by MDL100,907. While D(2) receptors are not implicated in their actions, in addition to antagonist properties at 5-HT(2A) receptors, blockade of alpha(1)-ARs and other, as yet unidentified, mechanisms may be involved. These data underpin interest in MDL100,907 as a potential antipsychotic agent.

SPECT imaging, clinical features, and cognition before and after low doses of amisulpride in schizophrenic patients with the deficit syndrome

The aim of the study was to examine the action of low-dose amisulpride (100 mg/d), an atypical antipsychotic from the benzamide class with a high affinity for the D2 and D3 dopamine receptors, given for 4 weeks in 19 schizophrenic patients with the deficit syndrome, in terms of clinical response, modifications in their cognitive performance and changes in brain perfusion values. A secondary objective was to distinguish between primary and secondary deficit, according to Carpenter's definition. Both efficacy and a relatively low rate of side effects of low-dose amisulpride in the deficit forms of schizophrenia were found as expected from earlier placebo-controlled studies. Our study found significant changes in the cerebral blood flow, before and after treatment, more marked in the frontal area and particularly in the dorso-lateral frontal area. A significant improvement of cognitive function was found after treatment, without a link to any particular changes in a loco-regional perfusion value. Finally, a distinction between primary and secondary deficit showed a higher percentage of clinical improvement in the patients with a secondary deficit. The psychometric and cerebral perfusion changes were no different in the two groups.

Switching antipsychotic medications: general recommendations and switching to amisulpride

As more and more novel antipsychotic agents are introduced, the need for practical guidelines on switching these medications is becoming increasingly important. Indications for a switch include situations where the patient or his family/caregiver requests a change in medication, where the patient cannot tolerate current treatment, where they have comorbid physical or psychiatric conditions or where they have achieved only a partial remission, are refractory to treatment or have relapsed. Cross-tapering is generally the most acceptable method of switching, although abrupt withdrawal may be necessary in some cases, such as when a patient develops a severe or acute reaction to their current treatment. Possible problems of switching include the risk of discontinuation reactions and the re-emergence of psychotic symptoms. The pharmacological profile of amisulpride means it has a relatively low potential for interactions with other drugs and may be started while discontinuing the previous antipsychotic. It should be started at the target dose for the patient's current symptoms. A retrospective questionnaire among 60 patients switching to amisulpride treatment was undertaken to identify the characteristics of patients switching antipsychotics and their reasons. Patients were switched from a variety of antipsychotic medications, both traditional (42% of patients) and atypical (58%). Most patients (87%) had at least two reasons for changing medication, with lack of efficacy, adverse events and treatment optimisation before reintegration being the most common. Contrary to recommendations, 89% of patients were switched abruptly between medications. A total of 62% of patients received amisulpride doses in the range 400-800 mg/day and most (72%) required no dose adjustment. The great majority of patients (87%) switched to amisulpride without problems.

A double-blind, randomised comparative trial of amisulpride versus olanzapine in the treatment of schizophrenia: short-term results at two months

OBJECTIVE

To compare the efficacy and safety of the atypical antipsychotics amisulpride and olanzapine in the treatment of acute psychotic exacerbations of schizophrenia.

DESIGN AND SETTING

A multinational, double-blind randomised clinical trial.

PATIENTS AND TREATMENT

Three hundred and seventy-seven patients with predominantly positive symptomatology were treated for six months with either amisulpride (200-800 mg/d) or olanzapine (5-20 mg/d).

MAIN OUTCOME MEASURES

Short-term results were analysed after two months of treatment. The primary efficacy measure was the change of score on the Brief Psychiatric Rating Scale (BPRS). Other measures of efficacy and safety were also evaluated.

RESULTS

Psychotic symptoms, as measured on the BPRS score, improved with both treatments, amisulpride being equivalent to olanzapine. All BPRS factor scores, as well as depressive symptoms, improved to a similar extent with both treatments. Less than five per cent of patients withdrew for adverse events, and there was no evidence for the emergence of extrapyramidal symptoms with either treatment. Statistically significant greater weight gain (2.7 +/- 3.9 kg) was observed during the study in the olanzapine group, compared with the amisulpride group (0.9 +/- 3.2 kg, p < 0.0001).

CONCLUSIONS

Amisulpride and olanzapine show equivalent efficacy at 2 months in the treatment of acute psychotic exacerbations of schizophrenia. Amisulpride offers a significant advantage in preserving body weight.