Benefical effects of sigma-1 agonist fluvoxamine for tardive dyskinesia and tardive akathisia in patients with schizophrenia: report of three cases

In vitro and in vivo sigma 1 receptor imaging studies in different disease states

The sigma receptor system has been classified into two distinct subtypes, sigma 1 (σ1R) and sigma 2 (σ2R). Sigma 1 receptors (σ1Rs) are involved in many neurodegenerative diseases and different central nervous system disorders such as Alzheimer's disease, Parkinson's disease, schizophrenia, and drug addiction, and pain. This makes them attractive targets for developing radioligands as tools to gain a better understanding of disease pathophysiology and clinical diagnosis. Over the years, several σ1R radioligands have been developed to image the changes in σ1R distribution and density providing insights into their role in disease development. Moreover, the involvement of both σ1Rs and σ2Rs with cancer make these ligands, especially those that are σ2R selective, great tools for imaging different types of tumors. This review will discuss the principles of molecular imaging using PET and SPECT, known σ1R radioligands and their applications for labelling σ1Rs under different disease conditions. Furthermore, this review will highlight σ1R radioligands that have demonstrated considerable potential as biomarkers, and an opportunity to fulfill the ultimate goal of better healthcare outcomes and improving human health.

Rapid improvement of obsessive-compulsive disorder associated with schizophrenia with cariprazine add-on in a subject under paliperidone long-acting injection: a case report

Obsessive-compulsive disorder is often associated with schizophrenia and may represent a significant challenge in the treatment as this comorbidity may not respond properly to antipsychotic medication and usually require a pharmacological and psychotherapeutic add-on. In the present case report, we present the case of a 26-year-old male blue-collar subject who developed obsessive-compulsive disorder after a year of complete remission of schizophrenia symptoms under paliperidone long-acting injection that rapidly resolved after low-dosage cariprazine add-on. No adverse effects were reported due to cariprazine- paliperidone long-acting injection combination.

A Report of Rabbit Syndrome Who Benefited from Sigma 1 Agonist Fluvoxamine

Rabbit Syndrome is an uncommon side effect of antipsychotic treatment. Although it is usually associated with typical antipsychotics, it can also be related to atypical antipsychotics. Anticholinergics are the most accepted treatment approach in treating Rabbit Syndrome. Fluvoxamine is a member of selective serotonin reuptake inhibitors and it is a potent agonist of sigma 1 receptors. In this article, we report a Rabbit Syndrome case who has benefited from fluvoxamine, in terms of both depressive disorder and Rabbit Syndrome; and present the data on the effects of sigma 1 agonist fluvoxamine on numerous movement disorders.

Evaluation of the Effect of Fluvoxamine in Patients With Schizophrenia Under Risperidone Treatment: A Clinical Trial

PURPOSE/BACKGROUND

The effectiveness of selective-serotonin reuptake inhibitors in the improvement of schizophrenia is a controversial issue. The aim of this study was to evaluate the effect of fluvoxamine on the symptoms of schizophrenia including positive and negative symptoms, cognitive impairment, and quality of life.

METHODS/PROCEDURES

This clinical trial was performed on 68 patients with chronic schizophrenia, treated with risperidone at 22 Bahman Hospital of Qazvin, Iran during 2015 to 2016. The patients were randomly divided into control and intervention groups (34 patients per group). The control group was treated with risperidone and biperiden, whereas the intervention group received fluvoxamine, besides risperidone, and biperiden. The participants completed the Wechsler Memory Scale, Scale for the Assessment of Positive Symptoms, Scale for the Assessment of Negative Symptoms (SANS), and the World Health Organization Quality of Life Scale, and the findings were statistically analyzed at baseline and postintervention (8 and 10 weeks).

FINDINGS/RESULTS

The mean ± SD Wechsler Memory Scale scores in the evaluated intervals (baseline, week 8, and week 10), respectively, were 70.58 ± 11.51, 70.76 ± 11.36, and 70.88 ± 11.40 in the control group and 74.76 ± 10.56, 77.76 ± 10.56, and 77.76 ± 10.73 in the intervention group (F = 126.73, P ≤ 0.001). The difference between the groups in terms of SANS and quality of life scores was significant in the specified intervals, SANS (F = 6.36, P = 0.004), and quality of life (F = 15.13, P ≤ 0.001). Nevertheless, no difference was observed in terms of Scale for the Assessment of Positive Symptoms scores (P > 0.05).

IMPLICATIONS/CONCLUSIONS

The results indicated that risperidone augmentation with fluvoxamine could significantly improve cognitive impairments and negative symptoms among patients with schizophrenia. Moreover, this augmentation led to higher quality of life among these patients.

Sigma-1 Receptor Agonists and Their Clinical Implications in Neuropsychiatric Disorders

Accumulating evidence suggests that sigma-1 receptors play a role in the pathophysiology of neuropsychiatric diseases, as well as in the mechanisms of some selective serotonin reuptake inhibitors (SSRIs). Among the SSRIs, the order of affinity for sigma-1 receptors is as follows: fluvoxamine > sertraline > fluoxetine > escitalopram > citalopram >> paroxetine. Some SSRIs (e.g., fluvoxamine, fluoxetine and escitalopram) and other drugs (donepezil , ifenprodil , dehydroepiandeterone (DHEA)) potentiate nerve-growth factor (NGF)-induced neurite outgrowth in PC12 cells, and these effects could be antagonized by the selective sigma-1 receptor antagonist NE-100. Furthermore, fluvoxamine, donepezil, and DHEA, but not paroxetine or sertraline, improved phencyclidine-induced cognitive deficits in mice, and these effects could be antagonized by NE-100. Several clinical studies showed that sigma-1 receptor agonists such as fluvoxamine and ifenprodil could have beneficial effects in patients with neuropsychiatric disorders. In this chapter, the authors will discuss the role of sigma-1 receptors in the mechanistic action of some SSRIs, donepezil, neurosteroids, and ifenprodil, and the clinical implications for sigma-1 receptor agonists .

The clinical potentials of adjunctive fluvoxamine to clozapine treatment: a systematic review

RATIONALE

New clozapine optimization strategies are warranted, as some patients do not achieve sufficient response and experience various adverse effects. Fluvoxamine is a potent CYP1A2 inhibitor and may increase the ratio of clozapine to its primary metabolite N-desmethylclozapine (NDMC).

OBJECTIVES

This study aims to review all pharmacodynamic effects and the adverse effect profile of changing the clozapine/NDMC ratio with adjunctive fluvoxamine.

METHODS

MEDLINE, Embase, and the Cochrane Library were searched with the search terms "clozapine" and "fluvoxamine" without any time limit. Language was restricted to English, Scandinavian, Polish, and German. Studies were sorted for relevance based on title and abstract. Clinical recommendations of potential indications/effects were graded as level A, B, C, or D depending on studies of high, moderate, low, or very low quality, respectively.

RESULTS

Based on data from 24 case reports/series, seven cohort studies, and two randomized controlled trials, 241 patients were studied. Evidence (A) supported that adjunctive fluvoxamine increased clozapine plasma levels. This may increase the probability of response in patients, where sufficient clozapine plasma levels cannot be achieved. Adjunctive fluvoxamine reduced metabolic adverse effects of clozapine (B) but not agranulocytosis risk (B). Although depressive or obsessive-compulsive symptoms may improve, a SSRI with no CYP1A2 inhibition should rather be used (C). No studies investigated the effect of adjunctive fluvoxamine to minimize clozapine rebound psychosis (D) or to reduce the effects of smoking on clozapine plasma levels (D).

CONCLUSIONS

Adjunctive fluvoxamine may have clinical potentials for optimizing clozapine treatment but further clinical studies are warranted to explore the clinical implications.

Drug-induced movement disorders

Movement disorders are frequently a result of prescription drugs or of illicit drug use. This article focuses on prescribed drugs but briefly mentions drugs of abuse. The main emphasis is on movement disorders caused by dopamine receptor-blocking agents. However, movement disorders caused by other drugs are also briefly discussed.

The pain of pain: challenges of animal behavior models

Berend Olivier has had a long-standing interest in the utility of animal models for a wide variety of therapeutic indications. His work has spanned multiple types of models, blending ethological, or species typical and naturalistic behaviors, along with methodologies based on learned behavior. He has consistently done so, from an analytical as well as predictive perspective, and has made multiple contributions while working in both the pharmaceutical industry and within an academic institution. Although focused primarily on psychiatric disorders, Berend has conducted research in the area of pain in humans and in animals, demonstrating an expansive appreciation for the breadth, scope and significance of the science and applications of the discipline of pharmacology to these diverse areas. This review focuses on the use of animal models in pain research from the perspective of the long-standing deficiencies in the development of therapeutics in this area and from a preclinical perspective where the translational weaknesses have been quite problematic. The challenges confronting animal models of pain, however, are not unique to this area of research, as they cut across several therapeutic areas. Despite the deficiencies, failures and concerns, existing animal models of pain continue to be of widespread use and are essential to progress in pain research as well as in other areas. Although not focusing on specific animal models of pain, this paper seeks to examine general issues facing the use of these models. It does so by exploring alternative approaches which capture recent developments, which build upon principles and concepts we have learned from Berend's contributions, and which provide the prospect of helping to address the absence of novel therapeutics in this area.