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

Effects of a single dose of amisulpride on functional brain changes during reward- and motivation-related processing using task-based fMRI in healthy subjects and patients with major depressive disorder - study protocol for a randomized clinical trial

BACKGROUND

Anhedonia and other deficits in reward- and motivation-related processing in psychiatric patients, including patients with major depressive disorder (MDD), represent a high unmet medical need. Neurobiologically, these deficits in MDD patients are mainly associated with low dopamine function in a frontostriatal network. In this study, alterations in brain activation changes during reward processing and at rest in MDD patients compared with healthy subjects are explored and the effects of a single low dose of the dopamine D2 receptor antagonist amisulpride are investigated.

METHODS

This is a randomized, controlled, double-blind, single-dose, single-center parallel-group clinical trial to assess the effects of a single dose of amisulpride (100 mg) on blood-oxygenation-level-dependent (BOLD) responses during reward- and motivation-related processing in healthy subjects (n = 60) and MDD patients (n = 60). Using functional magnetic resonance imaging (fMRI), BOLD responses are assessed during the monetary incentive delay (MID) task (primary outcome). Exploratory outcomes include BOLD responses and behavioral measures during the MID task, instrumental learning task, effort-based decision-making task, social incentive delay task, and probabilistic reward task as well as changes in resting state functional connectivity and cerebral blood flow.

DISCUSSION

This study broadly covers all aspects of reward- and motivation-related processing as categorized by the National Institute of Mental Health Research Domain Criteria and is thereby an important step towards precision psychiatry. Results regarding the immediate effects of a dopaminergic drug on deficits in reward- and motivation-related processing not only have the potential to significantly broaden our understanding of underlying neurobiological processes but might eventually also pave the way for new treatment options.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05347199. April 12, 2022.

Differential Effects of Aripiprazole and Amisulpride on Negative and Cognitive Symptoms in Patients With First-Episode Psychoses

INTRODUCTION

Aripiprazole is hypothesized to have an effect on negative and cognitive symptoms in schizophrenia. Likewise, amisulpride is one of the only second-generation antipsychotics with which an effect on negative symptoms is reported. In the present study, we compare the effect of aripiprazole and amisulpride in initially antipsychotic-naïve patients with first-episode psychoses.

METHODS

Psychopathology and cognitive measures from two consecutive cohorts of antipsychotic-naïve first episode psychotic patients were obtained before and after 6 weeks of antipsychotic monotherapy with either aripiprazole or amisulpride. Matched healthy controls were included to account for retest effects on the cognitive measures. Analyses of variance (repeated-measures ANOVA) were performed to detect effect of time and possible cohort^*time interactions.

RESULTS

Longitudinal data was obtained from 47 and 48 patients treated for 6 weeks with amisulpride or aripiprazole, respectively. For the Wallwork negative symptom dimension, there was a cohort^*time interaction [F _{(1, 93)} = 4.29, p = 0.041] and a significant effect of time [F _{(1, 93)} = 6.03, p = 0.016], which was driven by an improvement in patients treated with aripiprazole [t ₍₄₇₎ = 4.1, p < 0.001] and not observed in patients treated with amisulpride (p > 0.5). For the eight cognitive measures, no cohort^*time interaction was found and neither was cognitive improvement in any of the cohorts when accounting for retest effect.

CONCLUSION

Patients treated with aripiprazole improved on negative symptoms, which was not the case for patients treated with amisulpride. This may point to a general effect of a partial D2 receptor agonist on negative symptoms in patients with first-episode psychoses. There was, however, no improvement in cognitive functions.

A meta-analysis of effectiveness of real-world studies of antipsychotics in schizophrenia: Are the results consistent with the findings of randomized controlled trials?

Randomized controlled trials (RCTs) have been considered as gold standard for establishing the efficacy and safety of investigational new drugs; nonetheless, the generalizability of their findings has been questioned. To address this issue, an increasing number of naturalistic studies and real-world database analyses have been conducted. The question of how much information from these two approaches is congruent or discrepant with each other is of great importance for the clinical practice. To answer this question, we focused on data from the antipsychotic (AP) treatment of schizophrenia. Our aim was two-fold: to conduct a meta-analysis of real-world studies (RWS), and to compare the results of RWS meta-analysis with previously published meta-analyses of RCTs. The principal measure of effectiveness was all-cause treatment discontinuation for both RWS and RCTs (when not available, then drop out for RCTs). We included publications for 8 selected APs (oral formulations of amisulpride, aripiprazole, clozapine, haloperidol, olanzapine, quetiapine, risperidone, and long-acting injectable (LAI) risperidone). We identified 11 RWS and 7 RCT meta-analyses for inclusion. Our results indicated that the RWS yielded statistically conclusive and consistent findings across individual investigations. For the overwhelming majority of the comparisons where both RWS and RCT meta-analyses were available, there was good congruency between the RWS and the RCT results. Our results support that RCTs, despite their limitations, provide evidence which is generalizable to real-world settings. This is an important finding for both regulators and clinicians. RWS can provide guidance for situations where no evidence is available from double-blind clinical trials.

White matter integrity associated with severity reductions in positive symptoms after amisulpride treatment in drug-free patients with schizophrenia

Amisulpride is an effective antipsychotic for the treatment of schizophrenia with a lower propensity for extrapyramidal adverse effects than conventional antipsychotics. However, no study has investigated white matter (WM) integrity in patients with schizophrenia in relation to treatment response after amisulpride administration. Here, we investigated the associations of WM integrity with severity reductions in clinical symptoms in drug-free patients with schizophrenia at an early stage of amisulpride treatment. Nineteen patients with schizophrenia (SZ) and 15 healthy controls (HCs) participated in the present study. Diffusion tensor imaging data were acquired from all participants at baseline. All SZ participants began treatment with 200 mg of amisulpride per day. The dose was increased up to 1200 mg/day within 2 weeks depending on the severity of clinical symptoms, and maintained for the subsequent 6 weeks. Initially, and after 8 weeks of amisulpride treatment, SZ participants were assessed for the severity of overall illness, positive and negative symptoms, and motor side effects. SZ participants showed lower integrity in several WM regions, including the corpus callosum and fronto-temporal connections, when compared to HCs. Furthermore, lower WM integrity in fronto-temporo-limbic regions at baseline was found to be associated with severity reductions in positive symptoms after 8 weeks. Our findings suggest that WM integrity at the early stage of treatment may serve as a possible predictive marker for treatment response.

Amisulpride Augmentation in Acute Catatonia

Benzodiazepines are the first-line treatment of catatonia, but a substantial number of patients do not respond to them. Amisulpride is one of the atypical antipsychotic that has been effective for negative symptoms of schizophrenia. We examined the effect of augmentation of oral low doses of amisulpride with lorazepam on resolution of catatonic symptoms. Fifteen patients with catatonia were treated with a combination of oral lorazepam (2-4 mg) with amisulpride (100 mg). Catatonic symptoms were rated using the Bush Francis Catatonia Rating Scale at the baseline and daily thereafter. There was complete resolution of catatonic symptoms on the third day in all patients. There was significant reduction of the total Bush Francis Catatonia Rating Scale score over time (F = 181.38, P < 0.001) with a strong effect size (partial η = 0.96). Augmentation of lorazepam with low-dose amisulpride can be a reliable strategy for management of catatonia.

Psychopharmacology of the negative symptoms: current status and prospects for progress

The past decade has witnessed a resurgence of interest in the development of novel pharmacological agents to treat the negative symptoms of schizophrenia. This review provides an overview of pharmacological approaches that have been evaluated as potential treatments and describes the emergence of several promising new approaches. First, we briefly describe recent methodological developments, including consensus-based clinical trial guidelines for patient selection criteria, symptom assessment, and trial duration. Next, we overview mono- and adjunctive-therapies that have been evaluated, including first- and second-generation antipsychotics, antidepressants, psychostimulants, molecules targeting cholinergic and glutamatergic systems, and hormones. We highlight the most promising pharmacological agents on the horizon, including glycine transporter-1 inhibitors, α7-nicotinic receptor positive allosteric modulators, and oxytocin, as well as non-pharmacological electromagnetic stimulation approaches. Further investigations, using optimal clinical trial design, hold considerable promise for discovering effective treatments for these functionally disabling symptoms in the near future.

Effects of single dose intranasal oxytocin on social cognition in schizophrenia

Deficits in social cognition are common in schizophrenia and predict poor community functioning. Given the current limitations of psychosocial treatments and the lack of pharmacological treatments for social cognitive deficits, the development of novel therapeutic agents could greatly enhance functional recovery in schizophrenia. This study evaluated whether a single dose of intranasal oxytocin acutely improves social cognitive functioning in schizophrenia. Twenty-three male veterans with schizophrenia completed baseline assessments of social cognition that were divided into lower-level (facial affect perception, social perception, detection of lies) and higher-level (detection of sarcasm and deception, empathy) processes. One week later, patients received the same battery after being randomized to a single dose of 40 IU intranasal oxytocin or placebo. Though the groups did not differ significantly on the social cognition composite score, oxytocin improved performance for the higher-level social cognitive tasks (Cohen's d=1.0, p=0.045). Subjects were unable to accurately guess which treatment they had received. The improvements found in higher-level social cognition encourage further studies into the therapeutic potential of oxytocin in schizophrenia.

The role of dopamine D(3) receptors in antipsychotic activity and cognitive functions

Dopamine D(3) receptors have a pre- and postsynaptic localization in brain stem nuclei, limbic parts of the striatum, and cortex. Their widespread influence on dopamine release, on dopaminergic function, and on several other neurotransmitters makes them attractive targets for therapeutic intervention. The signaling pathways of D(3) receptors are distinct from those of other members of the D(2)-like receptor family. There is increasing evidence that D(3) receptors can form heteromers with dopamine D(1), D(2), and probably other G-protein-coupled receptors. The functional consequences remain to be characterized in more detail but might open new interesting pharmacological insight and opportunities. In terms of behavioral function, D(3) receptors are involved in cognitive, social, and motor functions, as well as in filtering and sensitization processes. Although the role of D(3) receptor blockade for alleviating positive symptoms is still unsettled, selective D(3) receptor antagonism has therapeutic features for schizophrenia and beyond as demonstrated by several animal models: improved cognitive function, emotional processing, executive function, flexibility, and social behavior. D(3) receptor antagonism seems to contribute to atypicality of clinically used antipsychotics by reducing extrapyramidal motor symptoms; has no direct influence on prolactin release; and does not cause anhedonia, weight gain, or metabolic dysfunctions. Unfortunately, clinical data with new, selective D(3) antagonists are still incomplete; their cognitive effects have only been communicated in part. In vitro, virtually all clinically used antipsychotics are not D(2)-selective but also have affinity for D(3) receptors. The exact D(3) receptor occupancies achieved in patients, particularly in cortical areas, are largely unknown, mainly because only nonselective or agonist PET tracers are currently available. It is unlikely that a degree of D(3) receptor antagonism optimal for antipsychotic and cognitive function can be achieved with existing antipsychotics. Therefore, selective D(3) antagonism represents a promising mechanism still to be fully exploited for the treatment of schizophrenia, cognitive deficits in schizophrenia, and comorbid conditions such as substance abuse.

Metabolic, endocrinologic and cardiac effects of amisulpride: a 24-week follow-up study

BACKGROUND

Amisulpride is a second-generation antipsychotic which has been proved to be effective in the control of both positive and negative symptoms of schizophrenia. In this study we aimed to determine metabolic, endocrinologic and cardiac effects of amisulpride commonly used in our clinical practice.

METHODS

A total of 18 patients (11 males, 7 females) diagnosed with schizophrenia received amisulpride at the dosage of 800 mg/day and were followed up for 24 weeks. Positive and negative psychotic symptoms, extrapyramidal and sexual side effects, metabolic, endocrinologic and cardiac parameters were evaluated at regular intervals.

RESULTS

Significant improvement in both positive and negative symptoms was observed in patients starting from the second week of treatment. Prolactin levels increased significantly both in men and women starting from the measurement on day 4. Prolactin elevation was significantly higher in women than in men. Increase in total cholesterol level became significant at week 24. No other significant difference was observed between weeks 1 and 24 regarding the other parameters.

CONCLUSIONS

The clinical data from the present study supports the fact that amisulpride is an effective and safe antipsychotic drug, but elevates prolactin levels in both sexes.

The acute and long-term effectiveness of amisulpride in patients with schizophrenia: results of a 12-month open-label prospective follow-up study

OBJECTIVE

To compare the effectiveness of amisulpride in acute (up to 8 weeks) and maintenance (week 8 to 12 months) phases of a 12-month course of treatment in a heterogeneous group of patients with schizophrenia.

METHODS

We conducted a 12-month, open-label clinical trial with flexible doses of amisulpride among 129 Korean patients with schizophrenia. The Positive and Negative Symptom Scale (PANSS) and several other scales measuring efficacy and tolerability were analyzed during the acute and maintenance phases.

RESULTS

The completion rates were 78.3% by week 8 and 55.8% by month 12. Total PANSS scores and scores on the negative-symptom and general-symptom subscales improved significantly during both acute and maintenance periods, but scores on the positive-symptom subscale improved only during the acute phase. Improvement during both treatment phases was significant in all other scales except for the Drug Attitude Inventory. The negative-symptom and mixed-symptom groups showed significant improvement in the PANSS negative subscale, the Clinical Global Impression scale, and the Global Assessment of Functioning during the maintenance period. Hyperprolactinemia and related events were commonly reported.

CONCLUSIONS

This study demonstrated the significant effectiveness and a good safety profile of amisulpride for treating acute and 12-month phases of schizophrenia under natural conditions.

Effects of atypical (risperidone) and typical (haloperidol) antipsychotic agents on astroglial functions

Although classical and atypical antipsychotics may have different neurotoxic effects, their underlying mechanisms remain to be elucidated, especially regarding neuroglial function. In the present study, we compared the atypical antipsychotic risperidone (0.01-10 μM) with the typical antipsychotic haloperidol (0.01-10 μM) regarding different aspects such as glutamate uptake, glutamine synthetase (GS) activity, glutathione (GSH) content, and intracellular reactive oxygen species (ROS) production in C6 astroglial cells. Risperidone significantly increased glutamate uptake (up to 27%), GS activity (14%), and GSH content (up to 17%). In contrast, haloperidol was not able to change any of these glial functions. However, at concentration of 10 μM, haloperidol increased (12%) ROS production. Our data contribute to the clarification of different hypothesis concerning the putative neural responses after stimulus with different antipsychotics, and may establish important insights about how brain rewiring could be enhanced.