Aripiprazole, A Drug that Displays Partial Agonism and Functional Selectivity

Pharmacological Treatment of Binge Eating Disorder and Frequent Comorbid Diseases

Binge eating disorder (BED) is the most common specific eating disorder (ED). It is frequently associated with attention deficit hyperactivity disorder (ADHD), depression, bipolar disorder (BD), anxiety disorders, alcohol and nicotine use disorder, and obesity. The aim of this narrative review was to summarize the evidence for the pharmacological treatment of BED and its comorbid disorders. We recommend the ADHD medication lisdexamfetamine (LDX) and the antiepileptic and antimigraine drug topiramate for the pharmacological treatment of BED. However, only LDX is approved for the treatment of BED in some countries. Medications to treat diseases frequently comorbid with BED include atomoxetine and LDX for ADHD; citalopram, fluoxetine, sertraline, duloxetine, and venlafaxine for anxiety disorders and depression; aripiprazole for manic episodes of BD; lamotrigine, lirasidone and lumateperone for depressive episodes of BD; naltrexone for alcohol use disorder; bupropion for nicotine use disorder; and liraglutide, semaglutide, and the combination of bupropion and naltrexone for obesity. As obesity is a frequent health consequence of BED, weight gain-inducing medications, such as the atypical antipsychotics olanzapine or clozapine, the novel antidepressant mirtazapine and tricyclic antidepressants, and the mood stabilizer valproate should be avoided where possible. It is currently unclear whether the novel and promising glucagon, glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide 1 (GLP-1) receptor agonists like tirzepatide and retatrutide help with BED and its comorbidities. However, these compounds have been reported to reduce binge eating in individuals with obesity or overweight.

Longitudinal cytokine and multi-modal health data of an extremely severe ME/CFS patient with HSD reveals insights into immunopathology, and disease severity

Introduction

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) presents substantial challenges in patient care due to its intricate multisystem nature, comorbidities, and global prevalence. The heterogeneity among patient populations, coupled with the absence of FDA-approved diagnostics and therapeutics, further complicates research into disease etiology and patient managment. Integrating longitudinal multi-omics data with clinical, health,textual, pharmaceutical, and nutraceutical data offers a promising avenue to address these complexities, aiding in the identification of underlying causes and providing insights into effective therapeutics and diagnostic strategies.

Methods

This study focused on an exceptionally severe ME/CFS patient with hypermobility spectrum disorder (HSD) during a period of marginal symptom improvements. Longitudinal cytokine profiling was conducted alongside the collection of extensive multi-modal health data to explore the dynamic nature of symptoms, severity, triggers, and modifying factors. Additionally, an updated severity assessment platform and two applications, ME-CFSTrackerApp and LexiTime, were introduced to facilitate real-time symptom tracking and enhance patient-physician/researcher communication, and evaluate response to medical intervention.

Results

Longitudinal cytokine profiling revealed the significance of Th2-type cytokines and highlighted synergistic activities between mast cells and eosinophils, skewing Th1 toward Th2 immune responses in ME/CFS pathogenesis, particularly in cognitive impairment and sensorial intolerance. This suggests a potentially shared underlying mechanism with major ME/CFS comorbidities such as HSD, Mast cell activation syndrome, postural orthostatic tachycardia syndrome (POTS), and small fiber neuropathy. Additionally, the data identified potential roles of BCL6 and TP53 pathways in ME/CFS etiology and emphasized the importance of investigating adverse reactions to medication and supplements and drug interactions in ME/CFS severity and progression.

Discussion

Our study advocates for the integration of longitudinal multi-omics with multi-modal health data and artificial intelligence (AI) techniques to better understand ME/CFS and its major comorbidities. These findings highlight the significance of dysregulated Th2-type cytokines in patient stratification and precision medicine strategies. Additionally, our results suggest exploring the use of low-dose drugs with partial agonist activity as a potential avenue for ME/CFS treatment. This comprehensive approach emphasizes the importance of adopting a patient-centered care approach to improve ME/CFS healthcare management, disease severity assessment, and personalized medicine. Overall, these findings contribute to our understanding of ME/CFS and offer avenues for future research and clinical practice.

Towards precision medicine of long-acting aripiprazole through population pharmacokinetic modelling

Population pharmacokinetic (popPK) models constitute a valuable tool for characterizing the pharmacokinetic properties of once-monthly long-acting injectable aripiprazole (LAI aripiprazole) and quantifying the sources of variability in drug exposure. Our aim is to develop a popPK model of both aripiprazole and its metabolite dehydro-aripiprazole in patients treated with LAI aripiprazole, and to personalize the dosing regimen of aripiprazole across different sub-groups of patients. This is a prospective study investigating the pharmacokinetics of LAI aripiprazole. A total of 93 patients were included, 21 for model development and 71 for external model evaluation. A one-compartment model with linear absorption and elimination adequately described both aripiprazole and dehydro-aripiprazole concentrations. The weight of the patients has been shown to be the factor that most influences the absorption. However, the metabolizing phenotype for CYP2D6 and the concomitant treatment with strong inhibitors of this cytochrome have been shown to be the covariates that most influence total drug exposure. This is the first popPK model developed for LAI aripiprazole that includes aripiprazole and its main active metabolite, dehydroaripiprazole. It provides a personalized dosage recommendation that maximizes the probability of achieving optimal therapeutic concentrations and minimizes the difficulties associated with trial-and-error therapeutic strategies carried out in clinical practice.

Application of a nucleophilic substitution reaction for spectrofluorimetric determination of aripiprazole in pharmaceutical dosage form and plasma matrix; greenness assessment

Aripiprazole is an antipsychotic medicine used to treat a variety of mental disorders, including irritability linked with autism disorder in children. Herein, a green and highly sensitive spectrofluorimetric method was developed for the determination of aripiprazole in pharmaceutical dosage form and plasma matrix. The method based on the formation of a fluorescent adduct from the nucleophilic substitution reaction of 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-chloride) with aripiprazole, which can be detected at 542 nm following excitation at 481 nm. Factors that affect the development and fluorescence sensitivity of the reaction product were investigated and optimized. The reaction yielded the most optimal fluorescence responses when it was performed using 1.5 mL of 0.2 % w/v NBD-chloride, 1.5 mL of borate buffer pH 9, heating at 80 °C for 20 min, and ethanol as a diluting solvent. The method was validated as per ICH guidelines for analytical and bioanalytical procedures. Good linearity was established between the fluorescence responses of the reaction product and aripiprazole concentrations in the range of 100-1200 ng/mL with adequate accuracy and precision results. The applied method was very sensitive and selectively determined aripiprazole in pharmaceutical and plasma matrices with no interferences. Furthermore, the compliance of the proposed method with the principles of green analytical chemistry was evaluated in comparison with the reported method using analytical eco-scale and AGREE metrics. The outputs proved that the proposed method complied more with the principles of green analytical chemistry than the reported method.

The Effect of Transcranial Direct Current Stimulation (tDCS) on Anorexia Nervosa: A Narrative Review

(1) Introduction: Anorexia nervosa (AN) is a severe, debilitating disease with high incidence and high mortality. The methods of treatment used so far are moderately effective. Evidence from neuroimaging studies helps to design modern methods of therapy. One of them is transcranial direct current stimulation (tDCS), a non-invasive brain neuromodulation technique. (2) Methods: The purpose of this narrative review is to bring together all studies investigating the use of tDCS in the treatment of AN and to evaluate its effect and efficiency. Searches were conducted in the Pubmed/Medline, Research Gate, and Cochrane databases. (3) Results: The literature search resulted in five articles. These studies provide preliminary evidence that tDCS has the potential to alter eating behaviour, body weight, and food intake. Additionally, tDCS reduced symptoms of depression. Throughout all trials, stimulation targeted the left dorsolateral prefrontal cortex (DLPFC). Although the number of studies included is limited, attempts were made to elucidate the potential mechanisms underlying tDCS action in individuals with AN. Recommendations for future tDCS research in AN were issued. (4) Conclusions: The included studies have shown that tDCS stimulation of the left DLPFC has a positive effect on AN clinical symptoms and may improve them, as measured by various assessment measures. It is important to conduct more in-depth research on the potential benefits of using tDCS for treating AN. This should entail well-designed studies incorporating advanced neuroimaging techniques, such as fMRI. The aim is to gain a better understanding of how tDCS works in AN.

Exploring the Association between Schizophrenia and Cardiovascular Diseases: Insights into the Role of Sigma 1 Receptor

Contemporary society is characterized by rapid changes. Various epidemiological, political and economic crises represent a burden to mental health of nowadays population, which may at least partially explain the increasing incidence of mental disorders, including schizophrenia. Schizophrenia is associated with premature mortality by at least 13-15 years. The leading cause of premature mortality in schizophrenia patients is high incidence of cardiovascular diseases. The specific-cause mortality risk for cardiovascular diseases in schizophrenia patients is more than twice higher as compared to the general population. Several factors are discussed as the factor of cardiovascular diseases development. Intensive efforts to identify possible link between schizophrenia and cardiovascular diseases are made. It seems that sigma 1 receptor may represent such link. By modulation of the activity of several neurotransmitter systems, including dopamine, glutamate, and GABA, sigma 1 receptor might play a role in pathophysiology of schizophrenia. Moreover, significant roles of sigma 1 receptor in cardiovascular system have been repeatedly reported. The detailed role of sigma 1 receptor in both schizophrenia and cardiovascular disorders development however remains unclear. The article presents an overview of current knowledge about the association between schizophrenia and cardiovascular diseases and proposes possible explanations with special emphasis on the role of the sigma 1 receptor.

Cannabidiol attenuates insular activity during motivational salience processing in patients with early psychosis

BACKGROUND

The mechanisms underlying the antipsychotic potential of cannabidiol (CBD) remain unclear but growing evidence indicates that dysfunction in the insula, a key brain region involved in the processing of motivationally salient stimuli, may have a role in the pathophysiology of psychosis. Here, we investigate whether the antipsychotic mechanisms of CBD are underpinned by their effects on insular activation, known to be involved in salience processing.

METHODS

A within-subject, crossover, double-blind, placebo-controlled investigation of 19 healthy controls and 15 participants with early psychosis was conducted. Administration of a single dose of CBD was compared with placebo in psychosis participants while performing the monetary incentive delay task, an fMRI paradigm. Anticipation of reward and loss were used to contrast motivationally salient stimuli against a neutral control condition.

RESULTS

No group differences in brain activation between psychosis patients compared with healthy controls were observed. Attenuation of insula activation was observed following CBD, compared to placebo. Sensitivity analyses controlling for current cannabis use history did not affect the main results.

CONCLUSION

Our findings are in accordance with existing evidence suggesting that CBD modulates brain regions involved in salience processing. Whether such effects underlie the putative antipsychotic effects of CBD remains to be investigated.

Permanent non-progressive cinnarizine and flunarizine-induced parkinsonism: An under-recognized tardive syndrome in the elderly?

Secondary parkinsonism induced by exposure to dopamine (DA) receptor antagonists as first and second generation antipsychotics, DA storage depleters, calcium channel blockers, benzamides substituted and other classes of drugs is traditionally believed to be completely reversible in most of patients following withdrawal of the offending drug even though after a variable time delay. The lack of recovery or initial full recovery with subsequent development of progressive parkinsonism has been regarded to result from an underlying subclinical degenerative process like PD unmasked by the inducing drug. These well-recognized clinical outcomes of drug-induced parkinsonism (DIP) have disregarded the existence of another outcome, characterized by permanent non-progressive parkinsonism. This syndrome may fullfil the criteria of tardive parkinsonism, a controversial entity currently referred to as a persistent condition without indication of its long-term course and clinical features. On reviewing the published literature on DIP, we have identified two prospective long-term follow-up of elderly patients in which parkinsonism induced by the calcium channel antagonists cinnarizine and flunarizine became permanent and non-progressive following drug discontinuation in a non-negligible proportion of patients, consistent with the clinical concept of a true tardive syndrome, according to currently accepted criteria. The authors hypothesize that the development of tardive parkinsonism might be due to a neurotoxic effect of the pharmacodynamic proprieties of the calcium channel blockers and their metabolites, exerted on post-synaptic striatal neurons and/or a neurotoxic damage on presynaptic DA neurons in patients without an underlying subclinical degenerative parkinsonism, so accounting for the stable and non-progressive course over time.

Oculogyric Crisis after Initiation of Aripiprazole: A Case Report of an Active Duty Service Member

Introduction

Oculogyric crisis is an acute dystonic reaction characterized by sustained, bilateral, and upward deviation of the eyes. It is a relatively uncommon extrapyramidal side effect of antipsychotic medications. Aripiprazole is an atypical antipsychotic that is FDA-approved for the treatment of schizophrenia, bipolar disorder, Tourette's disorder, and treatment resistant major depressive disorder. Compared to other antipsychotics, it is thought to have a lower propensity for causing dystonic side effects. Clinical Case. This case report is of a 19-year-old male who was psychiatrically hospitalized for first episode psychosis and initiated on low-dose oral aripiprazole. Three days after initiation of the medication, the patient was found to be markedly anxious and pacing around his room. Exam was notable for intermittent upward eye rolling, sustained upward conjugate gaze, and limited downward gaze. No other facial dyskinetic movements were observed. Treatment. The patient's oral aripiprazole was held, and he was administered 50 mg of oral diphenhydramine with improvement in symptoms within one hour. Ocular symptoms, dizziness, frontal headache, and pacing were resolved the following morning. He declined reinitiation of an antipsychotic medication.

Conclusion

Aripiprazole-induced acute dystonia, specifically OGC, is a rare potential adverse effect of aripiprazole. Risk factors include male gender, young age, use of typical antipsychotics, and initiation or uptitration of an antipsychotic. Even though atypical antipsychotics including aripiprazole are associated with lower risk for extrapyramidal symptoms, the possibility of oculogyric dystonia merits close monitoring especially in young, male, and drug naive patients. Anticholinergic agents such as diphenhydramine can treat symptoms of acute dystonia.

Concurrent measures of impulsive action and choice are partially related and differentially modulated by dopamine D1- and D2-like receptors in a rat model of impulsivity

Impulsivity is a multidimensional construct, but the relationships between its constructs and their respective underlying dopaminergic underpinnings in the general population remain unclear. A cohort of Roman high- (RHA) and low- (RLA) avoidance rats were tested for impulsive action and risky decision-making in the rat gambling task, and then for delay discounting in the delay-discounting task to concurrently measure the relationships among the three constructs of impulsivity using a within-subject design. Then, we evaluated the effects of dopaminergic drugs on the three constructs of impulsivity, considering innate differences in impulsive behaviors at baseline. Risky decision-making and delay-discounting were positively correlated, indicating that both constructs of impulsive choice are related. Impulsive action positively correlated with risky decision-making but not with delay discounting, suggesting partial overlap between impulsive action and impulsive choice. RHAs showed a more impulsive phenotype in the three constructs of impulsivity compared to RLAs, demonstrating the comorbid nature of impulsivity in a population of rats. Amphetamine increased impulsive action and had no effect on risky decision-making regardless of baseline levels of impulsivity, but it decreased delay discounting only in high impulsive RHAs. In contrast, while D₁R and D₃R agonism as well as D_2/3R partial agonism decreased impulsive action regardless of baseline levels of impulsivity, D_2/3R agonism decreased impulsive action exclusively in high impulsive RHAs. Irrespective of baseline levels of impulsivity, risky decision-making was increased by D₁R and D_2/3R agonism but not by D₃R agonism or D_2/3R partial agonism. Finally, while D₁R and D₃R agonism, D_2/3R partial agonism and D₂R blockade increased delay discounting irrespective of baseline levels of impulsivity, D_2/3R agonism decreased it in low impulsive RLAs only. These findings indicate that the acute effects of dopamine drugs were partially overlapping across dimensions of impulsivity, and that only D_2/3R agonism showed baseline-dependent effects on impulsive action and impulsive choice.

Antipsychotic drug-aripiprazole against schizophrenia, its therapeutic and metabolic effects associated with gene polymorphisms

Second-generation antipsychotics are widely used for the treatment of schizophrenia. Aripiprazole (ARI) is classified as a third-generation antipsychotic drug with a high affinity for dopamine and serotonin receptors. It is considered a dopamine-system stabilizer without severe side effects. In some patients the response to ARI treatment is inadequate and they require an effective augmentation strategy. It has been found that the response to the drug and the risk of adverse metabolic effects can be related to gene polymorphisms. A reduced dose is recommended for CYP2D6 poor metabolizers; moreover, it is postulated that other polymorphisms including CYP3A4, CYP3A5, ABCB1, DRD2, and 5-HTRs genes influence the therapeutic effect of ARI. ARI can increase the levels of prolactin, C-peptide, insulin, and/or cholesterol possibly due to specific genetic variants. It seems that a pharmacogenetic approach can help predict drug response and improve the clinical management of patients with schizophrenia.

Drug-Induced Gambling Disorder: Epidemiology, Neurobiology, and Management

Problematic gambling has been suggested to be a possible consequence of dopaminergic medications used mainly in neurological conditions, i.e. pramipexole and ropinirole, and possibly by one antipsychotic compound, aripiprazole. Patients with Parkinson's disease, restless legs syndrome and other conditions potentially treated with dopamine agonists, as well as patients treated for psychotic disorders, are vulnerable patient groups with theoretically increased risk of developing gambling disorder (GD), for example due to higher rates of mental ill-health in these groups. The aim of the present paper is to review the epidemiological, clinical, and neurobiological evidence of the association between dopaminergic medications and GD, and to describe risk groups and treatment options. The neurobiology of GD involves the reward and reinforcement system, based mainly on mesocorticolimbic dopamine projections, with the nucleus accumbens being a crucial area for developing addictions to substances and behaviors. The addictive properties of gambling can perhaps be explained by the reward uncertainty that activates dopamine signaling in a pathological manner. Since reward-related learning is mediated by dopamine, it can be altered by dopaminergic medications, possibly leading to increased gambling behavior and a decreased impulse control. A causal relationship between the medications and GD seems likely, but the molecular mechanisms behind this association have not been fully described yet. More research is needed in order to fully outline the clinical picture of GD developing in patient groups with dopaminergic medications, and data are needed on the differentiation of risk in different compounds. In addition, very few interventional studies are available on the management of GD induced by dopaminergic medications. While GD overall can be treated, there is need for treatment studies testing the effectiveness of tapering of the medication or other gambling-specific treatment modalities in these patient groups.

Network Analysis of the Structure of the Core Symptoms and Clinical Correlates in Comorbid Schizophrenia and Gambling Disorder

Few studies have analyzed the clinical profile of treatment-seeking patients with the comorbid presence of schizophrenia (SCZ) and gambling disorder (GD), which warrants new research to assess the network structure of this complex mental condition. The aim of this study was to explore the organization of the symptoms and other clinical correlates of SCZ with GD. Network analysis was applied to a sample of N = 179 SCZ patients (age range: 19-70 years, mean=39.5, SD=9.9) who met clinical criteria for gambling disorder-related problems. Variables included in the network were the core GD symptoms according to the DSM-5, psychotic and paranoid ideation levels, global psychological distress, GD severity measures (debts and illegal behavior related with gambling), substances (tobacco, alcohol, and illegal drugs), and personality profile. The nodes with the highest authority in the network (variables of highest relevance) were personality traits and psychological distress. Four empirical modules/clusters were identified, and linkage analysis identified the nodes with the highest closeness (bridge nodes) to be novelty seeking and reward dependence (these traits facilitate the transition between the modules). Identification of the variables with the highest centrality/linkage can be particularly useful for developing precise management plans to prevent and treat SCZ with GD.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11469-022-00983-y.

Block of Voltage-Gated Sodium Channels by Aripiprazole in a State-Dependent Manner

Aripiprazole is an atypical antipsychotic drug, which is prescribed for many psychiatric diseases such as schizophrenia and mania in bipolar disorder. It primarily acts as an agonist of dopaminergic and other G-protein coupled receptors. So far, an interaction with ligand- or voltage-gated ion channels has been classified as weak. Meanwhile, we identified aripiprazole in a preliminary test as a potent blocker of voltage-gated sodium channels. Here, we present a detailed analysis about the interaction of aripiprazole with the dominant voltage-gated sodium channel of heart muscle (hNa_v1.5). Electrophysiological experiments were performed by means of the patch clamp technique at human heart muscle sodium channels (hNa_v1.5), heterologously expressed in human TsA cells. Aripiprazole inhibits the hNa_v1.5 channel in a state- but not use-dependent manner. The affinity for the resting state is weak with an extrapolated K_r of about 55 µM. By contrast, the interaction with the inactivated state is strong. The affinities for the fast and slow inactivated state are in the low micromolar range (0.5–1 µM). Kinetic studies indicate that block development for the inactivated state must be described with a fast (ms) and a slow (s) time constant. Even though the time constants differ by a factor of about 50, the resulting affinity constants were nearly identical (in the range of 0.5 µM). Besides this, aripirazole also interacts with the open state of the channel. Using an inactivation deficit mutant, an affinity of about 1 µM was estimated. In summary, aripiprazole inhibits voltage-gated sodium channels at low micromolar concentrations. This property might add to its possible anticancer and neuroprotective properties.

Spironolactone alleviates schizophrenia-related reversal learning in Tcf4 transgenic mice subjected to social defeat

Cognitive deficits are a hallmark of schizophrenia, for which no convincing pharmacological treatment option is currently available. Here, we tested spironolactone as a repurposed compound in Tcf4 transgenic mice subjected to psychosocial stress. In this ‘2-hit’ gene by environment mouse (GxE) model, the animals showed schizophrenia-related cognitive deficits. We had previously shown that spironolactone ameliorates working memory deficits and hyperactivity in a mouse model of cortical excitatory/inhibitory (E/I) dysbalance caused by an overactive NRG1-ERBB4 signaling pathway. In an add-on clinical study design, we used spironolactone as adjuvant medication to the standard antipsychotic drug aripiprazole. We characterized the compound effects using our previously established Platform for Systematic Semi-Automated Behavioral and Cognitive Profiling (PsyCoP). PsyCoP is a widely applicable analysis pipeline based on the Research Domain Criteria (RDoC) framework aiming at facilitating translation into the clinic. In addition, we use dimensional reduction to analyze and visualize overall treatment effect profiles. We found that spironolactone and aripiprazole improve deficits of several cognitive domains in Tcf4tg x SD mice but partially interfere with each other’s effect in the combination therapy. A similar interaction was detected for the modulation of novelty-induced activity. In addition to its strong activity-dampening effects, we found an increase in negative valence measures as a side effect of aripiprazole treatment in mice. We suggest that repurposed drug candidates should first be tested in an adequate preclinical setting before initiating clinical trials. In addition, a more specific and effective NRG1-ERBB4 pathway inhibitor or more potent E/I balancing drug might enhance the ameliorating effect on cognition even further.

Aripiprazole Improved Post-Streptococcal Dyskinesia by Modulating Dopaminergic Activity: A Case Report

This case report aimed to discuss the efficacy of aripiprazole for dyskinesia in patients with functional movement disorder after streptococcal infection, with its biological action of modulating dopamine hyperactivity in the basal ganglia as a dopamine partial agonist. This report has shown that the [18F] N -(3-Fluoropropyl)-2β-carbon ethoxy-3β-(4-iodophenyl) nortropane positron emission tomography findings of the patient revealed that the dopamine hyperactivity in the basal ganglia at baseline was normalized after aripiprazole treatment due to its balancing effect as a dopamine partial agonist.

Lower Vitamin C Levels Are Associated With Less Improvement in Negative Symptoms in Initially Antipsychotic-Naïve Patients With First-Episode Psychosis

Low levels of vitamin C have been observed in patients with schizophrenia and psychosis, and vitamin C may affect the dopaminergic system. Likewise, antipsychotic medication modulates striatal dopamine D2 receptors. We measured vitamin C levels in 52 patients with first-episode psychoses (24 females, age 23.1 ± 5.2 years) and 57 matched HCs (20 females, age 22.7 ± 4.3 years) before and after 6 weeks where patients received aripiprazole monotherapy (mean dose 10.4 mg ± 4.8 mg). At baseline, patients displayed lower levels of vitamin C (57.4 ± 25.9 µM) than controls (72.7 ± 21.4 µM) (t = 3.4, P = .001). Baseline symptoms and vitamin C levels were not correlated. Higher baseline vitamin C levels were associated with more improvement in negative symptoms (n = 39, R2 = 0.20, F = 8.2, P = .007), but not with age, sex, or p-aripiprazole. Because negative symptoms are generally considered challenging to alleviate, a potential adjunctive effect of vitamin C on treatment response should be tested in future randomized clinical trials.

Case series on aripiprazole and dopamine supersensitivity psychosis

A potential link between switching to aripiprazole and worsening of psychosis was first reported in the early 2000s. There have since been numerous published case reports describing this phenomenon, but only recently has the concept of a theoretical aripiprazole-induced dopamine supersensitivity psychosis (DSP) caused by D2 receptor activation in patients undergoing a switch to aripiprazole appeared in the literature. There is less awareness in clinical practice of the possibility of inducing DSP with aripiprazole, which may be particularly severe in some patients. The objective of this article is to present four cases demonstrating rapid and dramatic onset of DSP during switching to aripiprazole. In each case, a patient with a Diagnostic and statistical manual of mental disorders (5th ed.) diagnosis of schizophrenia experienced severe worsening of psychosis within 4-5 days of abrupt switching to aripiprazole from a full D2 antagonist. To our knowledge, this is the first case series characterizing the previously well-documented worsening of psychosis during switching to aripiprazole specifically as aripiprazole-induced DSP. We discuss clinical relevance, prevention and future directions. Careful cross-titration per clinical practice guidelines may reduce occurrence of DSP during aripiprazole switching or augmentation treatment.

Orexin-a elevation in antipsychotic-treated compared to drug-free patients with schizophrenia: A medication effect independent of metabolic syndrome

BACKGROUND/PURPOSE

Orexin-A levels are reportedly increased in antipsychotic (APD)-treated patients with schizophrenia compared to healthy controls and have been associated with metabolic abnormalities. It is not clear whether the orexin-A elevation is related specifically to the drug (APDs) effect, which should be clarified by including a drug-free group for comparison, or related to drug-induced metabolic abnormalities.

METHODS

Blood orexin-A levels and metabolic profiles were compared between 37 drug-free, 45 aripiprazole-treated, and 156 clozapine-treated patients with schizophrenia. The association between orexin-A and metabolic outcomes were examined. We explored the effects of APDs treatment and metabolic status on orexin-A levels by linear regression.

RESULTS

Patients under APDs treatment had increased orexin-A levels compared to drug-free patients, with aripiprazole-treated group having higher orexin-A levels than clozapine-treated group. Higher orexin-A levels reduced the risks of metabolic syndrome (MS) and type 2 diabetes mellitus, indicating a relationship between orexin-A levels and metabolic problems. After adjusting the effect from metabolic problems, we found APD treatment is still associated with orexin-A regulation, with aripiprazole more significantly than clozapine.

CONCLUSION

With the inclusion of drug-free patients rather than healthy controls for comparison, we demonstrated that orexin-A is upregulated following APD treatment even after we controlled the potential effect from MS, suggesting an independent effect of APDs on orexin-A levels. Furthermore, the effect differed between APDs with dissimilar obesogenicity, i.e. less obesogenicity likely associated with higher orexin-A levels. Future prospective studies exploring the causal relationship between APDs treatment and orexin-A elevation as well as the underlying mechanisms are warranted.

Case report: Open bite as an extrapyramidal side effect with aripiprazole, a dopamine partial agonist

Long-term, fixed-point posttreatment observation of orthodontically treated patients provided us with the opportunity to capture the onset, development, and improvement of open bite, a type of malocclusion. Based on the chronological sequence of events, i.e., a tendency for open bite to worsen with increasing aripiprazole dosage and to improve with decreasing dosage, it was inferred that the onset of malocclusion was caused by extrapyramidal symptoms related to aripiprazole dosage. Physicians should be aware of this side effect when prescribing aripiprazole to children and adolescents. Careful consideration of medication history is necessary when dentists treat open bite in children and adolescents.

Dose-response analysis of aripiprazole in patients with schizophrenia in Taiwan

BACKGROUND

Aripiprazole is a third-generation antipsychotic agent with acceptable efficacy and a good safety profile. Previous studies have indicated the therapeutic serum concentration of aripiprazole to be 100 to 350 ng/ml; however, most of these studies examined a Western population. Patients with schizophrenia from Tungs' Taichung MetroHarbor Hospital in central Taiwan were recruited to analyze the dose-response relationship of aripiprazole in the Chinese population.

OBJECTIVE

We aimed to investigate whether a serum concentration of aripiprazole higher than the current suggested range leads to higher response rates.

DESIGN

A prospective cohort study was designed to investigate the response rates in different studied cohorts grouped by serum concentration of aripiprazole.

DATA SOURCES AND METHODS

Data of 64 patients who presented to a single medical center in central Taiwan and who received therapeutic drug monitoring (TDM) were obtained. Serum concentrations of aripiprazole were correlated with the clinical response of patients by using the Clinical Global Impressions (CGI) scores.

RESULTS

The mean concentration of aripiprazole was 432.1 ± 275.1 ng/ml in the study cohort. Among the much-improved patients, the mean serum concentration of aripiprazole was 494 ± 273 ng/ml (25th-75th percentiles 264-666 ng/ml), which was higher than the current recommended therapeutic target of 100-350 ng/ml for aripiprazole. The response rate in the severe group (baseline CGI score of 6 or 7) was significantly higher than in the moderate group (baseline CGI score of 4 or 5; 86.7% versus 55.9%, p = 0.007).

CONCLUSION

A significantly higher response rate was observed in the study cohort with serum aripiprazole concentrations over 300 ng/ml. Therefore, dosing higher than the current recommended range may potentially improve the treatment efficacy in the Chinese population. Because the serum concentration varies among patients due to multiple intrinsic and extrinsic factors, TDM, especially in outpatients, is recommended if the clinical response is limited.

Bioequivalence of 2 Aripiprazole Orally Disintegrating Tablets in Healthy Chinese Volunteers Under Fasting and Fed Conditions

To assess the bioequivalence of 2 formulations of aripiprazole orally disintegrating tablets and to monitor their safety and tolerability in Chinese subjects, a single-site, open-label, randomized, 2-preparation, single-dose, 2-period crossover design was conducted. All 60 subjects were randomly divided into the fasting group and the fed group. Blood samples were collected at scheduled times after a single oral dose of orodispersible tablets containing 10 mg of aripiprazole. In the fasting state, the geometric mean ratios (90% confidence intervals [CIs]) of the test/reference formulation were 92.22%-100.20% for the area under the concentration-time curve (AUC) from time zero to the last measured concentration (AUC_0-t ), 91.73%-100.14% for the AUC from administration to infinite time (AUC_0-∞ ), and 98.52%-112.52% for the maximum plasma concentration (C_max ). In the fed state, AUC_0-t , AUC_0-∞ , and C_max were 92.23%-100.20%, 91.73%-100.14%, and 95.91%-105.13%, respectively. The 90%CIs of the test/reference AUC ratio and C_max ratio were within the acceptance range of 80.00%-125.00% for bioequivalence. Neither the maximum peak plasma concentration (t_max ) nor the terminal elimination half-life (t_1/2 ) showed any significant difference. No serious adverse events) were encountered during the study. The test and reference formulations were bioequivalent under both fasting and fed conditions and were found to be safe and tolerated.

Risperidone versus aripiprazole fracture risk in children and adolescents with autism spectrum disorders

Risperidone and aripiprazole, commonly used antipsychotics in children with autism spectrum disorder (ASD), have previously been associated with elevated fracture risk in other populations. The aim of this study was to evaluate and compare the risk of fracture among children with ASD using risperidone or aripiprazole. This was a retrospective, propensity-score matched cohort study, set between January 2013 and December 2018. We used the MarketScan Medicaid insurance data, which covers multiple states of the United States. We included ASD children aged 2-18 years, who were new users of aripiprazole or risperidone and with no prior history of antipsychotic use or fractures. The main exposure was the continued use of aripiprazole or risperidone. The incidence rates of any fracture during follow-up were evaluated, and the risk between aripiprazole and risperidone was compared via Cox-proportional hazard models. Results were stratified by age, sex, duration of exposure and fracture site. In total, 3312 patients (78% male; mean [SD] age 11.0 [3.7] years) were identified for each cohort. Over the full duration of follow-up, fracture incidence rates per 1000 patient-years were 23.2 for risperidone and 38.4 for aripiprazole (hazard ratio and 95% confidence interval: 0.60 [0.44-0.83]). Risks were similar between cohorts throughout the first 180 days on treatment, but significantly higher in the aripiprazole group thereafter. Extremity fractures drove most of the increased risk, with the biggest differences in lower leg and ankle fractures. Differences widened for children aged 10 years or younger (HR [95% CI]: 0.47 [0.30-0.74]). In conclusion, compared to aripiprazole, risperidone was associated with 40% lower risk of fracture. Further analysis on the mechanism and long-term bone health of antipsychotic-treated children with ASD is warranted. LAY SUMMARY: We compared the risk of bone fractures among 6624 children with autism spectrum disorder (ASD), half of whom used risperidone and half of whom used aripiprazole. Taking other factors into account, risks were similar between the two groups throughout the first 180 days on treatment, but significantly higher in the aripiprazole group thereafter. The biggest differences were in lower leg and ankle fractures. Overall, compared with aripiprazole, risperidone was associated with 40% lower risk of fracture.

Increased risk for developing gambling disorder under the treatment with pramipexole, ropinirole, and aripiprazole: A nationwide register study in Sweden

Gambling Disorder (GD) has recently been reclassified from an impulse-control disorder to a behavioural addiction and, as in other addictive disorders, the dopaminergic reward system is involved. According to neuroimaging studies, alterations within the striatal dopaminergic signalling can occur in GD. However, the findings to date are controversial and there has been no agreement yet on how the reward system is affected on a molecular basis. Within the last 20 years, there has been growing evidence for a higher risk to develop GD in response to certain dopaminergic medication. Especially the dopamine agonists pramipexole and ropinirole, and the dopamine modulator aripiprazole seem to increase the likelihood for GD. The goal of this study was to examine the association between a prescription for either of the three pharmaceuticals and a GD diagnosis in a large cross-sectional study of the Swedish population. Compared to patients with any other dopaminergic drug prescription (38.7% with GD), the diagnosis was more common in patients with a dopamine agonist prescription (69.8% with GD), resulting in an odds ratio of 3.2. A similar association was found between aripiprazole prescriptions and GD diagnoses, which were analysed within the subgroup of all patients with schizophrenia or a schizotypal, delusional, or another non-mood psychotic disorder. An aripiprazole prescription increased the likelihood of GD (88.8%) in comparison to patients without an aripiprazole prescription (71.2%) with an odds ratio of 3.4. This study contributes to the increasingly reliable evidence for an association between several dopaminergic drugs and a higher risk for developing GD. Therefore, one future research goal should be a better understanding of the neurobiology in GD to be able to design more selective dopaminergic medication with less severe side effects. Additionally, this knowledge could enable the development of pharmacotherapy in GD and other addictive disorders.

Reversibility of Antipsychotic-Induced Weight Gain: A Systematic Review and Meta-Analysis

BACKGROUND AND AIMS

Weight gain is a major adverse effect of antipsychotic medication, negatively affecting physical and mental well-being. The objective of this study was to explore if dose reduction, discontinuation, switch to a partial agonist, or switch from polypharmacy to monotherapy will lead to weight loss.

METHODS

Controlled and uncontrolled studies reporting the effects of discontinuation, dose reduction, switch to a partial agonist, or switch from polypharmacy to monotherapy on weight were included. Primary outcome was difference in weight compared to maintenance groups based on controlled studies. Secondary outcome was change in weight from initiation of one of the included interventions until follow-up in a pre-post analysis.

RESULTS

We identified 40 randomized controlled trials and 15 uncontrolled studies including 12,279 individuals. The effect of the interventions, i.e. dose reduction, drug discontinuation, or switch to a partial agonis, reduced the weight with 1.5 kg (95% CI -2.03 to -0.98; P < 0.001) compared to maintenance treatment. The weight change from pre to post was a reduction of 1.13 kg (95% CI -1.36 to -0.90; P < 0.001).

CONCLUSION

We found a significant but small reduction in weight, suggesting that antipsychotic-induced weight gain can be reversed to some degree. Only a few studies were designed to address the question as primary outcome, which limits the generalizability of our findings.

Effectiveness of 2-year treatment with aripiprazole long-acting injectable and comparison with paliperidone palmitate

BACKGROUND

The pragmatic management of psychotic disorders is more complex than that delivered in a controlled trial environment. Therefore, this study aims to evaluate the real-world effectiveness of aripiprazole long-acting injectable (ALAI) and compare it with another commonly used long-acting anti-psychotic, once-monthly paliperidone palmitate (PP1M).

METHODS

This naturalistic, independent 4-year mirror image study compared the mean number and length of hospital admissions 2 years before and 2 years after treatment initiation with ALAI. Retention rates, discontinuation reasons and level of adherence were also recorded. Furthermore, indirect comparisons were made between treatment outcomes on ALAI and PP1M.

RESULTS

A total of 109 eligible patients with a severe mental illness (65% with schizophrenia and 35% with other diagnosis) commenced on ALAI and 173 patients (69% with schizophrenia and 31% with other diagnoses) initiated on PP1M were included. Of these, 37% on ALAI and 34% on PP1M stopped treatment at 2 years; retention rates were most favourable for the schizophrenia group on PP1M. Patients were more likely to discontinue due to lack of effectiveness on ALAI and due to tolerability issues on PP1M. Those who continued for 2 years on ALAI (n = 69), demonstrated an overall decrease of 84% in the mean number and 88% in the mean length of hospital admissions compared with the 2 years before initiation. Although patients on ALAI appeared to have a significantly higher bed occupancy the 2-year period before initiation than patients on PP1M, the reductions in hospitalizations were comparable across both cohorts after 2 years of treatment.

CONCLUSIONS

The introduction of ALAI had a substantial impact on long-term clinical outcomes in this naturalistic cohort; more than half of patients continued treatment and had no admission during 2 years of follow up. There were no significant differences in hospitalisation rates between patients on ALAI and PP1M at 2 years.

Dopamine in Autism Spectrum Disorders-Focus on D2/D3 Partial Agonists and Their Possible Use in Treatment

Autism spectrum disorders (ASD) are a group of disorders characterized by impairment in social communication and repetitive and stereotyped behaviors. ASD etiology is very complex, including the effect of both genetic and environmental factors. So far, no specific treatment for the core symptoms of ASD has been developed, although attempts have been made for the treatment of repetitive behavior. The pharmacological treatment is aimed at treating non-specific symptoms such as irritability and aggression. Recent studies pointed out to the possible role of altered dopamine signaling in mesocorticolimbic and nigrostriatal circuits in ASD. In addition, several research pointed out to the association of dopamine receptors polymorphism and ASD, specifically repetitive and stereotyped behavior. In this paper, we will provide a review of the studies regarding dopamine signaling in ASD, existing data on the effects of D2/D3 partial agonists in ASD, possible implications regarding their individual receptor profiles, and future perspectives of their possible use in ASD treatment.

Effect of aripiprazole as an adjunct to atypical antipsychotics on weight and metabolic profile: a 12-week open-label trial

BACKGROUND

Atypical antipsychotics are widely prescribed, yet have been associated with weight gain and metabolic syndrome.

AIM

To study the effect of adjunct low-dose aripiprazole on weight and metabolic parameters of subjects on atypical antipsychotics (olanzapine, clozapine or risperidone).

METHODS

The study was carried out as an open-label trial with a fixed dose of 5 mg aripiprazole added to the patient's current antipsychotic for 12 weeks. The primary outcome measure was mean change in weight, while secondary outcome measures included change in waist circumference; fasting blood glucose; HbA1c; triglycerides; total, HDL and LDL cholesterol levels; functioning; and neurocognition.

RESULTS

For the overall study (n = 55), there was no significant effect of adjunct aripiprazole on the weight of the subjects. However, the clozapine group achieved significant weight loss (p = 0.002) and also had significant improvements in total cholesterol (p < 0.001), HDL (p = 0.016), LDL (p = 0.044) and triglyceride levels (p = 0.038). The olanzapine group had significant improvement in triglycerides (p = 0.001), and other metabolic parameters for this group showed improvement trends, but did not reach statistical significance. The risperidone group did not show any significant improvement in weight or metabolic parameters.

CONCLUSIONS

The study adds support to the adjunctive use of aripiprazole to clozapine for weight loss and improvement in metabolic profile, and for reduction in cardiometabolic risk for patients on olanzapine.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT02949752.

Dopamine, Cognitive Impairments and Second-Generation Antipsychotics: From Mechanistic Advances to More Personalized Treatments

The pharmacological treatment of cognitive impairments associated with schizophrenia is still a major unmet clinical need. Indeed, treatments with available antipsychotics generate highly variable cognitive responses among patients with schizophrenia. This has led to the general assumption that antipsychotics are ineffective on cognitive impairment, although personalized medicine and drug repurposing approaches might scale down this clinical issue. In this scenario, evidence suggests that cognitive improvement exerted by old and new atypical antipsychotics depends on dopaminergic mechanisms. Moreover, the newer antipsychotics brexpiprazole and cariprazine, which might have superior clinical efficacy on cognitive deficits over older antipsychotics, mainly target dopamine receptors. It is thus reasonable to assume that despite more than 50 years of elusive efforts to develop novel non-dopaminergic antipsychotics, dopamine receptors remain the most attractive and promising pharmacological targets in this field. In the present review, we discuss preclinical and clinical findings showing dopaminergic mechanisms as key players in the cognitive improvement induced by both atypical antipsychotics and potential antipsychotics. We also emphasize the concept that these mechanistic advances, which help to understand the heterogeneity of cognitive responses to antipsychotics, may properly guide treatment decisions and address the unmet medical need for the management of cognitive impairment associated with schizophrenia.

Regulation of Reactive Oxygen Species-Mediated Damage in the Pathogenesis of Schizophrenia

The biochemical integrity of the brain is paramount to the function of the central nervous system, and oxidative stress is a key contributor to cerebral biochemical impairment. Oxidative stress, which occurs when an imbalance arises between the production of reactive oxygen species (ROS) and the efficacy of the antioxidant defense mechanism, is believed to play a role in the pathophysiology of various brain disorders. One such disorder, schizophrenia, not only causes lifelong disability but also induces severe emotional distress; however, because of its onset in early adolescence or adulthood and its progressive development, consuming natural antioxidant products may help regulate the pathogenesis of schizophrenia. Therefore, elucidating the functions of ROS and dietary antioxidants in the pathogenesis of schizophrenia could help formulate improved therapeutic strategies for its prevention and treatment. This review focuses specifically on the roles of ROS and oxidative damage in the pathophysiology of schizophrenia, as well as the effects of nutrition, antipsychotic use, cognitive therapies, and quality of life on patients with schizophrenia. By improving our understanding of the effects of various nutrients on schizophrenia, it may become possible to develop nutritional strategies and supplements to treat the disorder, alleviate its symptoms, and facilitate long-term recovery.

Treatment of psychosis in Parkinson's disease and dementia with Lewy Bodies: A review

There is a considerable overlap between Parkinson's Disease Dementia (PDD) and Dementia with Lewy Bodies (DLB). They present a challenge therapeutically, with regard to morbidity and mortality risk. In particular, symptoms of psychosis in these conditions augur a considerably increased burden. To date, there has been a myriad of prospective, retrospective and case studies examining the use of neuroleptics in the treatment of psychotic symptoms in PDD/DLB. Clozapine has the most robust evidence base however its use is limited by agranulocytosis risk and the associated need for frequent blood count monitoring. Quetiapine is more readily used, however, it has a more equivocal evidence base, in terms of efficacy. Other neuroleptics have thus far demonstrated mixed results with increased risk of extrapyramidal worsening. In addition to the atypical agents, the introduction of pimavanserin has provided another treatment option for Parkinson's Disease Psychosis (PDP), decreasing concern for deterioration in motor function. We await further research to confidently demonstrate its efficacy and safety in DLB psychosis. Cholinesterase inhibitors likely have a limited role in treating milder psychosis symptomatology in DLB and perhaps PDD. After review of the current literature for antipsychotic therapy in both PDD and DLB, we provide a logical framework for addressing psychotic symptoms in each condition.

Severe parkinsonism under treatment with antipsychotic drugs

The aim of the study was to assess rates of severe parkinsonism related to different antipsychotic drugs (APDs) using data from an observational pharmacovigilance programme in German-speaking countries-Arzneimittelsicherheit in der Psychiatrie (AMSP). Data on APD utilization and reports of severe APD-induced parkinsonism were collected in 99 psychiatric hospitals in Austria, Germany and Switzerland during the period 2001-2016. Of 340,099 patients under surveillance, 245,958 patients were treated with APDs for the main indications of schizophrenic disorders, depression, mania and organic mental disorders. A total of 200 events of severe APD-induced parkinsonism were identified (0.08%). First-generation low-potency APDs were significantly less often implicated (0.02%) than second-generation APDs (0.07%) and first-generation high-potency APDs (0.16%). Among the second-generation APDs, amisulpride and risperidone ranked highest. The phenothiazines were associated with significantly lower rates of severe parkinsonism (0.02%) than those of the butyrophenones (0.11%) and thioxanthenes (0.12%). In 71 cases (35.5%), more than 1 drug was considered responsible for the induction of severe parkinsonism. In 44 patients (22.0%), the symptoms were extremely severe, leading to complete immobility and/or massive complications such as pneumonia and severe injuries due to falls. Higher age (> 60 years) was associated with significantly higher rates of severe parkinsonism, as were the diagnoses of schizophrenic disorder or mania. The large number of patients included in the present survey allows for the comparison of severe parkinsonism rates related to different APD classes and single APDs. The first-generation low-potency APDs had significantly reduced risk of severe parkinsonism compared not only to high potency but also to second-generation APDs.

Second-Generation Antipsychotics and Dysregulation of Glucose Metabolism: Beyond Weight Gain

Second-generation antipsychotics (SGAs) are the cornerstone of treatment for schizophrenia because of their high clinical efficacy. However, SGA treatment is associated with severe metabolic alterations and body weight gain, which can increase the risk of type 2 diabetes and cardiovascular disease, and greatly accelerate mortality. Several underlying mechanisms have been proposed for antipsychotic-induced weight gain (AIWG), but some studies suggest that metabolic changes in insulin-sensitive tissues can be triggered before the onset of AIWG. In this review, we give an outlook on current research about the metabolic disturbances provoked by SGAs, with a particular focus on whole-body glucose homeostasis disturbances induced independently of AIWG, lipid dysregulation or adipose tissue disturbances. Specifically, we discuss the mechanistic insights gleamed from cellular and preclinical animal studies that have reported on the impact of SGAs on insulin signaling, endogenous glucose production, glucose uptake and insulin secretion in the liver, skeletal muscle and the endocrine pancreas. Finally, we discuss some of the genetic and epigenetic changes that might explain the different susceptibilities of SGA-treated patients to the metabolic side-effects of antipsychotics.

Effects of aripiprazole on circadian prolactin secretion related to pharmacogenetics in healthy volunteers

Aripiprazole treatment in schizophrenic patients was previously associated with lower or normalized prolactin levels. Genetic variants in cytochrome P450 (CYP) (CYP2D6), dopamine receptor (DRD2, DRD3) and serotonin receptor (HTR2A, HTR2C) genes were previously associated with antipsychotic-induced hyperprolactinaemia. Our aim was to evaluate whether aripiprazole affects prolactin secretion and its relationship with pharmacogenetics. Thirty-one healthy volunteers receiving a 10-mg single oral dose of aripiprazole were genotyped for 12 polymorphisms in CYP2D6, DRD2, DRD3, HTR2A and HTR2C genes by qPCR. Aripiprazole and dehydro-aripiprazole plasma concentrations were measured by HPLC-MS/MS. Prolactin concentrations of the 31 volunteers taking aripiprazole and 12 volunteers receiving ibuprofen were determined by ELISA. Prolactin concentrations after ibuprofen intake were considered as control, since it is known to cause no effect. Prolactin concentrations were slightly higher in the aripiprazole group compared to the ibuprofen group. All prolactin pharmacokinetic parameters were higher in females than in males. CYP2D6 poor and intermediate metabolizers had notably higher prolactin C_max and AUC_0-12 than normal and ultrarapid metabolizers. The DRD3 rs6280 polymorphism affected prolactin levels: volunteers carrying Ser/Ser genotype had significantly lower prolactin levels than volunteers carrying the Gly allele. Furthermore, HTR2C rs3813929 C/C homozygotes had significantly lower prolactin levels than T allele carriers. Nevertheless, aripiprazole did increase prolactin levels compared to ibuprofen.

Rational Design of Multitarget-Directed Ligands: Strategies and Emerging Paradigms

Due to the complexity of multifactorial diseases, single-target drugs do not always exhibit satisfactory efficacy. Recently, increasing evidence indicates that simultaneous modulation of multiple targets may improve both therapeutic safety and efficacy, compared with single-target drugs. However, few multitarget drugs are on market or in clinical trials, despite the best efforts of medicinal chemists. This article discusses the systematic establishment of target combination, lead generation, and optimization of multitarget-directed ligands (MTDLs). Moreover, we analyze some MTDLs research cases for several complex diseases in recent years and the physicochemical properties of 117 clinical multitarget drugs, with the aim to reveal the trends and insights of the potential use of MTDLs.

Aripiprazole for the treatment of duloxetine-induced hyperprolactinemia: A case report

BACKGROUND

It is well known that aripiprazole co-treatment effectively reduces antipsychotic-induced hyperprolactinemia. However, the effectiveness of aripiprazole to treat high prolactin levels induced by antidepressant drugs with serotoninergic activity, such as duloxetine, remains unknown.

CASE PRESENTATION

An 18-year-old female diagnosed with major depressive disorder (MDD) was treated with 100 mg sertraline once daily. After two weeks, galactorrhoea was observed. Blood biochemical tests revealed an elevated serum prolactin level of 241 ng/mL. Physiological causes and additional potential pathological causes were ruled out. Therefore, sertraline was cross tapered with mirtazapine. Galactorrhoea ceased, but the side-effect of sedation prompted a switch to 40 mg duloxetine twice daily. After two weeks, the patient developed menstrual irregularities and milky discharge concomitant with a serum prolactin level of 205 ng/mL. As a result, duloxetine was decreased to 60 mg once daily, and aripiprazole was initiated at 2.5 mg daily and titrated to 5 mg daily. Two weeks after the initiation of dual therapy, galactorrhoea stopped, and prolactin levels decreased to 118 ng/mL. After eight weeks, prolactin levels decreased to 39 ng/mL, and menstruation returned to normal. After antidepressant therapy finished, prolactin levels normalized to 19 ng/mL.

CONCLUSION

The case suggests that adjunctive aripiprazole may be useful as a treatment option for duloxetine-induced hyperprolactinemia in MDD.

Current Concepts and Treatments of Schizophrenia

Schizophrenia is a debilitating mental illness which involves three groups of symptoms, i.e., positive, negative and cognitive, and has major public health implications. According to various sources, it affects up to 1% of the population. The pathomechanism of schizophrenia is not fully understood and current antipsychotics are characterized by severe limitations. Firstly, these treatments are efficient for about half of patients only. Secondly, they ameliorate mainly positive symptoms (e.g., hallucinations and thought disorders which are the core of the disease) but negative (e.g., flat affect and social withdrawal) and cognitive (e.g., learning and attention disorders) symptoms remain untreated. Thirdly, they involve severe neurological and metabolic side effects and may lead to sexual dysfunction or agranulocytosis (clozapine). It is generally agreed that the interactions of antipsychotics with various neurotransmitter receptors are responsible for their effects to treat schizophrenia symptoms. In particular, several G protein-coupled receptors (GPCRs), mainly dopamine, serotonin and adrenaline receptors, are traditional molecular targets for antipsychotics. Comprehensive research on GPCRs resulted in the exploration of novel important signaling mechanisms of GPCRs which are crucial for drug discovery: intentionally non-selective multi-target compounds, allosteric modulators, functionally selective compounds and receptor oligomerization. In this review, we cover current hypotheses of schizophrenia, involving different neurotransmitter systems, discuss available treatments and present novel concepts in schizophrenia and its treatment, involving mainly novel mechanisms of GPCRs signaling.

Making Sense of Pharmacology: Inverse Agonism and Functional Selectivity

Constitutive receptor activity/inverse agonism and functional selectivity/biased agonism are 2 concepts in contemporary pharmacology that have major implications for the use of drugs in medicine and research as well as for the processes of new drug development. Traditional receptor theory postulated that receptors in a population are quiescent unless activated by a ligand. Within this framework ligands could act as agonists with various degrees of intrinsic efficacy, or as antagonists with zero intrinsic efficacy. We now know that receptors can be active without an activating ligand and thus display "constitutive" activity. As a result, a new class of ligand was discovered that can reduce the constitutive activity of a receptor. These ligands produce the opposite effect of an agonist and are called inverse agonists. The second topic discussed is functional selectivity, also commonly referred to as biased agonism. Traditional receptor theory also posited that intrinsic efficacy is a single drug property independent of the system in which the drug acts. However, we now know that a drug, acting at a single receptor subtype, can have multiple intrinsic efficacies that differ depending on which of the multiple responses coupled to a receptor is measured. Thus, a drug can be simultaneously an agonist, an antagonist, and an inverse agonist acting at the same receptor. This means that drugs have an additional level of selectivity (signaling selectivity or "functional selectivity") beyond the traditional receptor selectivity. Both inverse agonism and functional selectivity need to be considered when drugs are used as medicines or as research tools.

Polypharmacology by Design: A Medicinal Chemist's Perspective on Multitargeting Compounds

Multitargeting compounds comprising activity on more than a single biological target have gained remarkable relevance in drug discovery owing to the complexity of multifactorial diseases such as cancer, inflammation, or the metabolic syndrome. Polypharmacological drug profiles can produce additive or synergistic effects while reducing side effects and significantly contribute to the high therapeutic success of indispensable drugs such as aspirin. While their identification has long been the result of serendipity, medicinal chemistry now tends to design polypharmacology. Modern in vitro pharmacological methods and chemical probes allow a systematic search for rational target combinations and recent innovations in computational technologies, crystallography, or fragment-based design equip multitarget compound development with valuable tools. In this Perspective, we analyze the relevance of multiple ligands in drug discovery and the versatile toolbox to design polypharmacology. We conclude that despite some characteristic challenges remaining unresolved, designed polypharmacology holds enormous potential to secure future therapeutic innovation.

Schizophrenia: synthetic strategies and recent advances in drug design

Schizophrenia is a complex and unpredictable mental disorder which affects several domains of cognition and behaviour. It is a heterogeneous illness characterised by positive, negative, and cognitive symptoms, often accompanied by signs of depression. In this tutorial review, we discuss recent progress in understanding the target sites and mechanisms of action of second-generation antipsychotic drugs. Progress in identifying and defining target sites has been accelerated recently by advances in neuroscience, and newly developed agents that regulate signalling by the main excitatory neurotransmitters in the brain are surveyed. Examples of novel molecules for the treatment of schizophrenia in preclinical and clinical development and their industrial sponsors are highlighted.

5-HT2C Receptor Structures Reveal the Structural Basis of GPCR Polypharmacology

Drugs frequently require interactions with multiple targets-via a process known as polypharmacology-to achieve their therapeutic actions. Currently, drugs targeting several serotonin receptors, including the 5-HT_2C receptor, are useful for treating obesity, drug abuse, and schizophrenia. The competing challenges of developing selective 5-HT_2C receptor ligands or creating drugs with a defined polypharmacological profile, especially aimed at G protein-coupled receptors (GPCRs), remain extremely difficult. Here, we solved two structures of the 5-HT_2C receptor in complex with the highly promiscuous agonist ergotamine and the 5-HT_2A-C receptor-selective inverse agonist ritanserin at resolutions of 3.0 Å and 2.7 Å, respectively. We analyzed their respective binding poses to provide mechanistic insights into their receptor recognition and opposing pharmacological actions. This study investigates the structural basis of polypharmacology at canonical GPCRs and illustrates how understanding characteristic patterns of ligand-receptor interaction and activation may ultimately facilitate drug design at multiple GPCRs.

Synthesis, Molecular Properties Estimations, and Dual Dopamine D2 and D3 Receptor Activities of Benzothiazole-Based Ligands

Neurleptic drugs, e.g., aripiprazole, targeting the dopamine D_2S and D₃ receptors (D_2SR and D₃R) in the central nervous system are widely used in the treatment of several psychotic and neurodegenerative diseases. Therefore, a new series of benzothiazole-based ligands (3-20) was synthesized by applying the bioisosteric approach derived from the selective D₃Rs ligand BP-897 (1) and its structurally related benz[d]imidazole derivative (2). Herein, introduction of the benzothiazole moiety was well tolerated by D_2SR and D₃R binding sites leading to antagonist affinities in the low nanomolar concentration range at both receptor subtypes. However, all novel compounds showed lower antagonist affinity to D₃R when compared to that of 1. Further exploration of different substitution patterns at the benzothiazole heterocycle and the basic 4-phenylpiperazine resulted in the discovery of high dually acting D_2SR and D₃R ligands. Moreover, the methoxy substitution at 2-position of 4-phenylpiperazine resulted in significantly (22-fold) increased D_2SR binding affinity as compared to the parent ligand 1, and improved physicochemical and drug-likeness properties of ligands 3-11. However, the latter structural modifications failed to improve the drug-able properties in ligands having un-substituted 4-phenylpiperazine analogs (12-20). Accordingly, compound 9 showed in addition to high dual affinity at the D_2SR and D₃R [K_i (hD_2SR) = 2.8 ± 0.8 nM; K_i (hD₃R) = 3.0 ± 1.6 nM], promising clogS, clogP, LE (hD_2SR, hD₃R), LipE (hD_2SR, hD₃R), and drug-likeness score values of −4.7, 4.2, (0.4, 0.4), (4.4, 4.3), and 0.7, respectively. Also, the deaminated analog 10 [K_i (hD_2SR) = 3.2 ± 0.4 nM; K_i (hD₃R) = 8.5 ± 2.2 nM] revealed clogS, clogP, LE (hD_2SR, hD₃R), LipE (hD_2SR, hD₃R) and drug-likeness score values of −4.7, 4.2, (0.4, 0.4), (3.9, 3.5), and 0.4, respectively. The results observed for the newly developed benzothiazole-based ligands 3-20 provide clues for the diversity in structure activity relationships (SARs) at the D_2SR and D₃R subtypes.