Emerging drugs for schizophrenia: an update

QSPR Analysis of Drugs for Treatment of Schizophrenia Using Topological Indices

Schizophrenia is a chronic psychotic disorder characterized primarily by cognitive deficits. Drugs and therapies are helpful in managing the symptoms, mostly with long-term compliance. There is a pressing need to design more efficient drugs with fewer adverse effects. Solubility, metabolic stability, toxicity, permeability, and transporter effects are important parameters in the efficacy of drug design, which in turn depend upon different physical and chemical characteristics of drugs. In recent years, there has been growing interest in developing computational tools for the discovery and development of drugs for schizophrenia. Some of these methods use machine learning algorithms to predict the efficacy and side effects of the potential drugs. Other studies have used computer simulations to understand the molecular mechanisms underlying the disease and identify new targets for drug development. Topological indices are numeric quantities linked to the chemical structure of drugs and predict the properties, reactivity, and stability of drugs through the quantitative structure-property relationship (QSPR). This work is aimed at using statistical techniques to link QSPR correlating properties with connectivity indices using linear regression. The QSPR model gives quite a better estimation of the properties of drugs, such as melting point, boiling point, enthalpy, flash point, molar refractivity, refractive index, complexity, molecular weight, and refractivity. Results are validated by comparing actual values to estimated values for the drugs.

Challenges in the clinical development of non-D2 compounds for schizophrenia

Schizophrenia is a chronic, heterogeneous, severe psychiatric disorder characterized by a spectrum of symptomology and is associated with substantial morbidity and mortality. For the last 70 years, available treatments have shared blockade of dopamine D2 receptors as their primary mechanism of action (MOA), the efficacy of which has been limited by incomplete resolution of all symptoms as well as treatment non-response in a select subset of patients. In addition, antipsychotics are associated with class-related side effects attributed to this primary MOA, including extrapyramidal symptoms (EPS). The need for non-D2 treatment options for patients which offer a novel risk/benefit profile is therefore apparent. There has been substantial investment in the research and development of non-D2 drug candidates. However, none of these programs have received successful regulatory approval by the FDA (as of Oct 2022). In this article, the scale of industry-sponsored clinical trials for D2-based investigational pharmacological treatments in schizophrenia was quantified and compared with investigational compounds with non-D2 MOAs. In a dataset of 545 clinical trials identified in ClinicalTrials.gov from January 2002 to July 2022, total enrollments in trials of non-D2-based compounds for the treatment of schizophrenia summed to approximately 34,000 patients, compared with 27,144 patients for D2-based compounds. These data indicate that there remains substantial and ongoing investment in the development of novel non-D2 options for schizophrenia, with a success rate measured by regulatory approval that is well-below recent benchmarks for the broader category of CNS drugs. Improved trial design, conduct, endpoints, and analyses/methods may influence signal detection and reliability to support development and registration of non-D2 compounds.

A systematic review of TMS and neurophysiological biometrics in patients with schizophrenia

BACKGROUND

Transcranial magnetic stimulation can be combined with electromyography (TMS-EMG) and electroencephalography (TMS-EEG) to evaluate the excitatory and inhibitory functions of the cerebral cortex in a standardized manner. It has been postulated that schizophrenia is a disorder of functional neural connectivity underpinned by a relative imbalance of excitation and inhibition. The aim of this review was to provide a comprehensive overview of TMS-EMG and TMS-EEG research in schizophrenia, focused on excitation or inhibition, connectivity, motor cortical plasticity and the effect of antipsychotic medications, symptom severity and illness duration on TMS-EMG and TMS-EEG indices.

METHODS

We searched PsycINFO, Embase and Medline, from database inception to April 2020, for studies that included TMS outcomes in patients with schizophrenia. We used the following combination of search terms: transcranial magnetic stimulation OR tms AND interneurons OR glutamic acid OR gamma aminobutyric acid OR neural inhibition OR pyramidal neurons OR excita* OR inhibit* OR GABA* OR glutam* OR E-I balance OR excitation-inhibition balance AND schizoaffective disorder* OR Schizophrenia OR schizophreni*.

RESULTS

TMS-EMG and TMS-EEG measurements revealed deficits in excitation or inhibition, functional connectivity and motor cortical plasticity in patients with schizophrenia. Increased duration of the cortical silent period (a TMS-EMG marker of γ-aminobutyric acid B receptor activity) with clozapine was a relatively consistent finding.

LIMITATIONS

Most of the studies used patients with chronic schizophrenia and medicated patients, employed cross-sectional group comparisons and had small sample sizes.

CONCLUSION

TMS-EMG and TMS-EEG offer an opportunity to develop a novel and improved understanding of the physiologic processes that underlie schizophrenia and to assess the therapeutic effect of antipsychotic medications. In the future, these techniques may also help predict disease progression and further our understanding of the excitatory/inhibitory balance and its implications for mechanisms that underlie treatment-resistant schizophrenia.

Characterization of six CaMKIIα variants found in patients with schizophrenia

The Ca²⁺/Calmodulin-dependent protein kinase II (CaMKII) is a central regulator of synaptic plasticity and has been implicated in various neurological conditions, including schizophrenia. Here, we characterize six different CaMKIIα variants found in patients with schizophrenia. Only R396stop disrupted the 12-meric holoenzyme structure, GluN2B binding, and synaptic localization. Additionally, R396stop impaired T286 autophosphorylation that generates Ca²⁺-independent “autonomous” kinase activity. This impairment in T286 autophosphorylation was shared by the R8H mutation, the only mutation that additionally reduced stimulated kinase activity. None of the mutations affected the levels of CaMKII expression in HEK293 cells. Thus, impaired CaMKII function was detected only for R396stop and R8H. However, two of the other mutations have been later identified also in the general population, and not all mutations found in patients with schizophrenia would be expected to cause disease. Nonetheless, for the R396stop mutation, the severity of the biochemical effects found here would predict a neurological phenotype.

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Two of six CaMKII variants found in patients with schizophrenia showed impairments

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R396stop disrupted holoenzyme structure, T286 autophosphorylation, and GluN2B binding

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R8H reduced T286 autophosphorylation and stimulated activity

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Two of the four other variants were later found also in the general population

Enantioenriched Positive Allosteric Modulators Display Distinct Pharmacology at the Dopamine D1 Receptor

(1) Background: Two first-in-class racemic dopamine D₁ receptor (D₁R) positive allosteric modulator (PAM) chemotypes (1 and 2) were identified from a high-throughput screen. In particular, due to its selectivity for the D₁R and reported lack of intrinsic activity, compound 2 shows promise as a starting point toward the development of small molecule allosteric modulators to ameliorate the cognitive deficits associated with some neuropsychiatric disease states; (2) Methods: Herein, we describe the enantioenrichment of optical isomers of 2 using chiral auxiliaries derived from (R)- and (S)-3-hydroxy-4,4-dimethyldihydrofuran-2(3H)-one (d- and l-pantolactone, respectively); (3) Results: We confirm both the racemate and enantiomers of 2 are active and selective for the D₁R, but that the respective stereoisomers show a significant difference in their affinity and magnitude of positive allosteric cooperativity with dopamine; (4) Conclusions: These data warrant further investigation of asymmetric syntheses of optically pure analogues of 2 for the development of D₁R PAMs with superior allosteric properties.

Paliperidone 3-Month Injection for Treatment of Schizophrenia: A Narrative Review

Given the typical age onset of schizophrenia, there are tremendous economic and social impacts that extend beyond the person and their families. One critical determinant of the diseases' impact is the patient's adherence to antipsychotic drug treatment. Approved in 2015 for the treatment of schizophrenia, paliperidone palmitate (Invega Trinza, a 3-month injection, noted as PP3M) is a second-generation long-acting injectable antipsychotic medication. Among the different formulations offered for palmitate paliperidone, including the 1 and 3-month formulations, the longer duration 3-month formulation was better at preventing relapse in schizophrenic patients. To date, different formulations of palmitate paliperidone that have been studied on relapse episodes of schizophrenia include once-daily extended-release oral paliperidone (ORAL paliperidone), once-monthly paliperidone palmitate (PP1M), and once-every-3-months paliperidone palmitate (PP3M). Post-hoc analyses show that patients who were withdrawn from PP1M paliperidone had the least risk of relapse, followed by patients withdrawn from PP3M and patients withdrawn from ORAL paliperidone. PP3M was better at preventing relapse compared to ORAL paliperidone. The results demonstrated that 50% of patients who were withdrawn from ORAL paliperidone, PP1M, or PP3M remained relapse-free for ~2, 6, and 13 months, respectively. Compared to PP1M, PP3M is just as safe and effective and has the added advantage of increased adherence related to a longer dose interval, decreasing the risk of relapse.

In situ-gelling starch nanoparticle (SNP)/O-carboxymethyl chitosan (CMCh) nanoparticle network hydrogels for the intranasal delivery of an antipsychotic peptide

Existing oral or injectable antipsychotic drug delivery strategies typically demonstrate low bioavailability to targeted brain regions, incentivizing the development of alternative delivery strategies. Delivery via the nasal cavity circumvents multiple barriers for reaching the brain but requires drug delivery vehicles with very specific properties to be effective. Herein, we report in situ-gelling and degradable bulk nanoparticle network hydrogels consisting of oxidized starch nanoparticles (SNPs) and carboxymethyl chitosan (CMCh) that enable intranasal delivery via spray, high nasal mucosal retention, and functional controlled release of the peptide drug PAOPA, a positive allosteric modulator of dopamine D2 receptor. PAOPA-loaded SNP-CMCh hydrogels can alleviate negative symptoms like behavioural abnormalities associated with schizophrenia (i.e. decreased social interaction time) for up to 72 h in an MK-801-induced pre-clinical rat model of schizophrenia at a low drug dosage (0.5 mg/kg); in comparison, conventional PAOPA administration via the intraperitoneal route requires twice the PAOPA dose to achieve a therapeutic effect that persists for only a few hours. This strategy offers potential for substantially decreasing re-administration frequencies and overall drug doses (and thus side-effects) of a range of potential antipsychotic drugs via a minimally-invasive administration route.

Discovery of fused heterocyclic carboxamide derivatives as novel α7-nAChR agonists: Synthesis, preliminary SAR and biological evaluation

The α7 nicotinic acetylcholine receptor (α7 nAChR) has emerged as a promising therapeutic target for schizophrenia. In our previous work, a novel series of α7-nAChR agonists bearing scaffold of indolizine were discovered. To explore the effect of aromaticity on the activity and find more active agents, herein, fused heterocyclic carboxamide derivatives were designed and synthesized in this study. Based on the evaluation by two-electrode voltage clamp in Xenopus oocytes, 27 of the synthesized compounds showed obvious agonism of α7 nAChR. Particularly, compounds 10a and 10e showed significantly higher E_max than EVP-6124. The result illustrated the importance of aromaticity to the activity of agonism. Compound 10a, which showed EC₅₀ of 1.88 μM and E_max of 72.4%, was further characterized comprehensively, including co-application with type II positive allosteric modulator PNU-120596, selectivity with other closely related ligand-gated ion channel, etc. The results showed that 10a showed moderate selectivity over other subtypes such as α4β2 and α3β4 nAChR. 10a evoked α7-like currents that were inhibited by MLA and enhanced in the presence of the α7 PAM PNU-120596. The analysis of binding mode and understanding of structure-activity relationship provided insights to develop more potent novel α7-nAChR agonists.

Keeping up with the therapeutic advances in schizophrenia: a review of novel and emerging pharmacological entities

Schizophrenia remains one of the most severe medical diseases. Current dopamine modulating first-generation and second-generation antipsychotics target mainly positive symptoms, but not/inadequately negative and cognitive symptoms. Additional challenges include non-adherence and adverse effects, especially cardiometabolic dysregulation. This review evaluates new/emerging pharmacological treatments for schizophrenia. Therapies targeting total symptoms include cannabidiol, D3 antagonist/5-HT1A partial agonist F17464, lumateperone (ITI-007), phosphodiesterase 10A (PDE10A) inhibitors MK-8189 and TAK-063, sodium nitroprusside, and trace amine-associated receptor-1 (TAAR1) agonist RO5263397 and SEP-363856. Treatments targeting negative symptoms include the PDE10A inhibitor LuAF-11167, 5-HT2A inverse agonist pimavanserin, sigma-2/5-HT2A antagonist roluperidone (MIN-101), and d-amino acid oxidase (DAAO) inhibitor TAK-831. Agents targeting primarily cognitive dysfunction are the glycine transporter-1 inhibitor BI-425809 and cannabidiol. Therapies targeting residual positive symptoms/treatment-resistant schizophrenia include pimavanserin, dopamine D1/D2 antagonist LuAF-35700, and DAAO inhibitor sodium benzoate. Two new long-acting injectable antipsychotic formulations, Aripiprazole Lauroxil NanoCrystal® and the first subcutaneous injectable LAI Perseris (RBP-7000), were recently approved by U.S. Food and Drug Administration, and positive results were announced for Risperidone ISM®, each achieving therapeutic levels within 24 hours, without need for initial oral cotreatment/loading injection-strategies. Paliperidone palmitate 6-monthly intramuscularly injectable and Risperidone subcutaneously injectable TV46000 are currently under investigation. Finally, the samidorphan+olanzapine combination targets reduced weight gain liability, while maintaining olanzapine's efficacy. Most of these trial programs are still ongoing or have yielded mixed or even negative results. Thus, additional mechanisms of action and agents require study to improve schizophrenia outcomes for total/positive symptoms with reduced adverse effects, but also cognitive symptoms, negative symptoms, and treatment resistance, the areas of greatest need in schizophrenia currently.

Dysregulation of auditory neuroplasticity in schizophrenia

Schizophrenia is a complex brain syndrome characterized by an array of positive symptoms (delusions, hallucinations, disorganized speech), negative symptoms (alogia, apathy, avolition) and cognitive impairments (memory, executive functions). Although investigations of the cognitive deficits in schizophrenia have primarily concentrated on disturbances affecting higher-order cognitive processes, there is an increasing realization that schizophrenia also affects early sensory processing, which might, in fact, play a significant role in the development of higher-order cognitive impairments. Recent evidence suggests that many of these early sensory processing impairments possibly arise from a dysregulation of plasticity regulators in schizophrenia, resulting in either reduced plasticity or excessive unregulated plasticity. The purpose of the present manuscript is to provide a concise overview of how the dysregulation of cortical plasticity mechanisms contributes to schizophrenia symptoms with an emphasis on auditory dysplasticity and to discuss its relevance for treatment outcomes. The idea that plasticity mechanisms are not constrained only within sensitive periods suggests that many functional properties of sensory neurons can be altered throughout the lifetime.

EPA guidance on physical activity as a treatment for severe mental illness: a meta-review of the evidence and Position Statement from the European Psychiatric Association (EPA), supported by the International Organization of Physical Therapists in Mental Health (IOPTMH)

Physical activity (PA) may be therapeutic for people with severe mental illness (SMI) who generally have low PA and experience numerous life style-related medical complications. We conducted a meta-review of PA interventions and their impact on health outcomes for people with SMI, including schizophrenia-spectrum disorders, major depressive disorder (MDD) and bipolar disorder. We searched major electronic databases until January 2018 for systematic reviews with/without meta-analysis that investigated PA for any SMI. We rated the quality of studies with the AMSTAR tool, grading the quality of evidence, and identifying gaps, future research needs and clinical practice recommendations. For MDD, consistent evidence indicated that PA can improve depressive symptoms versus control conditions, with effects comparable to those of antidepressants and psychotherapy. PA can also improve cardiorespiratory fitness and quality of life in people with MDD, although the impact on physical health outcomes was limited. There were no differences in adverse events versus control conditions. For MDD, larger effect sizes were seen when PA was delivered at moderate-vigorous intensity and supervised by an exercise specialist. For schizophrenia-spectrum disorders, evidence indicates that aerobic PA can reduce psychiatric symptoms, improves cognition and various subdomains, cardiorespiratory fitness, whilst evidence for the impact on anthropometric measures was inconsistent. There was a paucity of studies investigating PA in bipolar disorder, precluding any definitive recommendations. No cost effectiveness analyses in any SMI condition were identified. We make multiple recommendations to fill existing research gaps and increase the use of PA in routine clinical care aimed at improving psychiatric and medical outcomes.

A Population Pharmacokinetic and Pharmacodynamic Analysis of RP5063 Phase 2 Study Data in Patients with Schizophrenia or Schizoaffective Disorder

Background and Objective

RP5063 is a novel multimodal dopamine (D)–serotonin (5-HT) stabilizer possessing partial agonist activity for D_2/3/4 and 5-HT_1A/2A, antagonist activity for 5-HT_2B/2C/7, and moderate affinity for the serotonin transporter. Phase 2 trial data analysis of RP5063 involving patients with schizophrenia and schizoaffective disorder defined: (1) the pharmacokinetic profile; and (2) the pharmacokinetic/pharmacodynamic relationships.

Methods

Pharmacokinetic sample data (175 patients on RP5063; 28 doses/patient) were analyzed, utilized one- and two-compartment models, and evaluated the impact of covariates. Pharmacodynamic analysis involved development of an E_max model.

Results

The pharmacokinetic analysis identified a one-compartment model incorporating body mass index influence on volume as the optimum construct, with fixed-effect parameters: (1) oral clearance (Cl/F), 5.11 ± 0.11 L/h; (2) volume of distribution (V_c/F), 328.00 ± 31.40 L; (3) absorption constant (ka) 0.42 ± 0.17 h⁻¹; (4) lag time (t lag) of 0.41 ± 0.02 h; and (5) a calculated half-life of 44.5 h. Pharmacokinetics were linear related to dose. An E_max model for total Positive and Negative Syndrome Scale (PANSS) scores as the response factor against cumulative area under the curve (AUC) provided fixed-effect estimates: (1) E_o = 87.3 ± 0.71 (PANSS Units; pu); (2) E_max = − 31.60 ± 4.05 (pu); and (3) AUC₅₀ = 89.60 ± 30.10 (µg·h/mL). The predicted PANSS improvement reflected a clinical dose range of 5–30 mg.

Conclusions

Pharmacokinetics of RP5063 behaved predictably and consistently. Pharmacodynamics were characterized using an E_max model, reflecting total PANSS score as a function of cumulative AUC, that showed high predictability and low variability when correlated with actual observations.

Electronic supplementary material

The online version of this article (10.1007/s13318-018-0472-z) contains supplementary material, which is available to authorized users.

The acute efficacy of antipsychotics in schizophrenia: a review of recent meta-analyses

Schizophrenia is the eighth leading cause of disability worldwide in people aged 15-44 years. Before antidopaminergic antipsychotics were introduced in the 1950s, no effective medications existed for the treatment of schizophrenia. This review summarizes key meta-analytic findings regarding antipsychotic efficacy in the acute treatment of schizophrenia, including clozapine in treatment-resistant patients. In the most comprehensive meta-analysis of randomized controlled trials conducted in multi-episode schizophrenia, antipsychotics outperformed placebo regarding total symptoms, positive symptoms, negative symptoms, depressive symptoms, quality of life and social functioning. Amongst these outcomes, the standardized mean difference for overall symptoms was largest, that is, 0.47 (95% credible interval = 0.42-0.51), approaching a medium effect size, being reduced to 0.38 when publication bias and small-trial effects were accounted for. A comparison of two meta-analyses indicated that first-episode patients, compared with multi-episode patients, were more likely to have at least minimal treatment response [⩾20% Positive and Negative Syndrome Scale (PANSS)/Brief Psychiatric Rating Scale (BPRS) score reduction: 81% versus 51%] and good response (⩾50% PANSS/BPRS score reduction: 52% versus 23%). In multi-episode schizophrenia, no response or worsening after 2 weeks of a therapeutic antipsychotic dose was highly predictive of not achieving a good response at endpoint (median treatment = 6 weeks: specificity = 86%; positive predictive value = 90%), suggesting a change in treatment should be considered in such cases. In first-episode psychosis, adequately dosed antipsychotic treatment trials for more than 2 weeks are recommended before using no response or worsening as a decision point for aborting a given antipsychotic. In clearly defined treatment-resistant schizophrenia, clozapine generally outperformed other antipsychotics, especially when dosed appropriately (target = 3-6 months' duration; trough clozapine level ⩾350-400 μg/L) with a response rate (⩾20% PANSS/BPRS) of 33% by 3 months of treatment. High antipsychotic doses and psychotropic combinations are unlikely to be superior to standard doses of antipsychotic monotherapy. Acute antipsychotic efficacy in schizophrenia depends on the targeted symptom domain (greater efficacy: total and positive symptoms, lesser efficacy: negative symptoms, depressive symptoms, social functioning and quality of life). Greater antipsychotic efficacy is associated with higher total baseline symptom severity, treatment-naïveté/first-episode status, shorter illness duration, and trials that are nonindustry sponsored and that have a lower placebo effect. The heterogeneity of antipsychotic response across individuals and key symptom domains, the considerable degree of nonresponse/treatment resistance in multi-episode patients, and the adverse effect potential of antipsychotics are major limitations, underscoring the need to develop new medications for the treatment of schizophrenia. Drug development should include matching patient subgroups, which are identified by means of clinical and biomarker variables, to mechanisms of action of novel medications, targeting specific symptom domains, and investigating mechanisms of action other than dopaminergic blockade.

The brief negative symptom scale (BNSS): Sensitivity to treatment effects

The Brief Negative Symptom Scale (BNSS) grew out of a recommendation by the NIMH-sponsored Consensus Development Conference on Negative Symptoms that a scale based on contemporary concepts be developed. We assessed sensitivity to change of the BNSS in a trial of MIN-101, which showed efficacy for negative symptoms (PANSS pentagonal model) at daily doses of 32 and 64mg/day. Using mixed-effects model for repeated measures, we examined change in BNSS total score and in the BNSS factors of anhedonia/avolition/asociality (AAA), and expressivity (EXP). Compared to placebo, the 64mg group (N=83) showed a significant decrease in BNSS total score (effect size d [ES] 0.56, p<0.01) and both factor scores (AAA ES=0.48, EXP ES=0.46, p<0.02 for both). Patients in the trial had minimal depression and positive symptom scores; covarying for disorganization, positive symptoms, or anxiety/depression did not cause a meaningful change in the significance of the BNSS total or factor scores in this group. The 32mg group (N=78) did not differ significantly from placebo (N=83) on BNSS total score (ES=0.33, p<0.09), AAA (ES=0.25, p<0.20) or EXP (ES=0.30, p<0.12) scores. These results demonstrate the BNSS is sensitive to change.

Efficacy and safety of antidepressant augmentation of continued antipsychotic treatment in patients with schizophrenia

OBJECTIVE

To evaluate the efficacy and safety of antidepressant augmentation of antipsychotics in schizophrenia.

METHODS

Systematic literature search (PubMed/MEDLINE/PsycINFO/Cochrane Library) from database inception until 10/10/2017 for randomized, double-blind, efficacy-focused trials comparing adjunctive antidepressants vs. placebo in schizophrenia.

RESULTS

In a random-effects meta-analysis (studies = 42, n = 1934, duration = 10.1 ± 8.1 weeks), antidepressant augmentation outperformed placebo regarding total symptom reduction [standardized mean difference (SMD) = -0.37, 95% confidence interval (CI) = -0.57 to -0.17, P < 0.001], driven by negative (SMD = -0.25, 95% CI = -0.44-0.06, P = 0.010), but not positive (P = 0.190) or general (P = 0.089) symptom reduction. Superiority regarding negative symptoms was confirmed in studies augmenting first-generation antipsychotics (FGAs) (SMD = -0.42, 95% CI = -0.77, -0.07, P = 0.019), but not second-generation antipsychotics (P = 0.144). Uniquely, superiority in total symptom reduction by NaSSAs (SMD = -0.71, 95% CI = -1.21, -0.20, P = 0.006) was not driven by negative (P = 0.438), but by positive symptom reduction (SMD = -0.43, 95% CI = -0.77, -0.09, P = 0.012). Antidepressants did not improve depressive symptoms more than placebo (P = 0.185). Except for more dry mouth [risk ratio (RR) = 1.57, 95% CI = 1.04-2.36, P = 0.03], antidepressant augmentation was not associated with more adverse events or all-cause/specific-cause discontinuation.

CONCLUSIONS

For schizophrenia patients on stable antipsychotic treatment, adjunctive antidepressants are effective for total and particularly negative symptom reduction. However, effects are small-to-medium, differ across antidepressants, and negative symptom improvement seems restricted to the augmentation of FGAs.

Dopamine serotonin stabilizer RP5063: A randomized, double-blind, placebo-controlled multicenter trial of safety and efficacy in exacerbation of schizophrenia or schizoaffective disorder

The study objectives were to evaluate the efficacy, safety, tolerability, and pharmacokinetics of RP5063 versus placebo. The study was conducted in adults with acute exacerbation of schizophrenia or schizoaffective disorder. This 28-day, multicenter, placebo-controlled, double-blind study randomized 234 subjects to RP5063 15, 30, or 50mg; aripiprazole; or placebo (3:3:3:1:2) once daily. The aripiprazole arm was included solely to show assay sensitivity and was not powered to show efficacy. The primary endpoint was change from baseline to Day 28/EOT (End-of-Treatment) in Positive and Negative Syndrome Scale (PANSS) total score; secondary endpoints included PANSS subscales, improvement ≥1 point on the Clinical Global Impressions-Severity (CGI-S), depression and cognition scales. The primary analysis of PANSS Total showed improvement by a mean (SE) of -20.23 (2.65), -15.42 (2.04), and -19.21 (2.39) in the RP5063 15, 30, and 50mg arms, versus -11.41 (3.45) in the placebo arm. The difference between treatment and placebo reached statistical significance for the 15mg (p=0.021) and 50mg (p=0.016) arms. Improvement with RP5063 was also seen for multiple secondary efficacy outcomes. Discontinuation for any reason was much lower for RP5063 (14%, 25%, 12%) versus placebo (26%) and aripiprazole (35%). The most common treatment-emergent adverse events (TEAE) in the RP5063 groups were insomnia and agitation. There were no significant changes in body weight, electrocardiogram, or incidence of orthostatic hypotension; there was a decrease in blood glucose, lipid profiles, and prolactin levels. In conclusion, the novel dopamine serotonin stabilizer, RP5063 is an efficacious and well-tolerated treatment for acute exacerbation of schizophrenia or schizoaffective disorder.

Investigational dopamine antagonists for the treatment of schizophrenia

INTRODUCTION

Schizophrenia is a debilitating illness with a chronic impact on social function and daily living. Although various antipsychotics are available, there are still many challenges and unmet needs. Thus, many compounds with diverse mechanisms have been investigated, but all approved antipsychotics still require interactions with dopamine D₂ receptors. Areas covered: We searched for investigational drugs using the key words 'dopamine' and 'schizophrenia' in American and European clinical trial registers (clinicaltrials.gov; clinicaltrialsregister.eu). Published articles were searched in PubMed, Embase, Medline, PsycINFO, Cumulative Index to Nursing and Allied Health Literature (CINAHL), the Web of Science and the Cochrane Central Register of Controlled Trials Library. Expert opinion: The prospect of developing a dopamine antagonist is hopeful. Brexpiprazole and cariprazine, which were agents listed as 'investigational dopamine antagonists,' just received FDA approval. Novel agents such as BL 1020, ITI-007, and JNJ-37822681 have solid published data available, and agents such as L-THP, Lu AF35700, S33138, and SB-773812 are under vigorous investigation. However, the expected benefits of the newly developed antagonists may not be great because they offer little enhanced efficacy for negative symptoms, cognition and functional outcomes.

Sleep deprivation as an experimental model system for psychosis: Effects on smooth pursuit, prosaccades, and antisaccades

Current antipsychotic medications fail to satisfactorily reduce negative and cognitive symptoms and produce many unwanted side effects, necessitating the development of new compounds. Cross-species, experimental behavioural model systems can be valuable to inform the development of such drugs. The aim of the current study was to further test the hypothesis that controlled sleep deprivation is a safe and effective model system for psychosis when combined with oculomotor biomarkers of schizophrenia. Using a randomized counterbalanced within-subjects design, we investigated the effects of 1 night of total sleep deprivation in 32 healthy participants on smooth pursuit eye movements (SPEM), prosaccades (PS), antisaccades (AS), and self-ratings of psychosis-like states. Compared with a normal sleep control night, sleep deprivation was associated with reduced SPEM velocity gain, higher saccadic frequency at 0.2 Hz, elevated PS spatial error, and an increase in AS direction errors. Sleep deprivation also increased intra-individual variability of SPEM, PS, and AS measures. In addition, sleep deprivation induced psychosis-like experiences mimicking hallucinations, cognitive disorganization, and negative symptoms, which in turn had moderate associations with AS direction errors. Taken together, sleep deprivation resulted in psychosis-like impairments in SPEM and AS performance. However, diverging somewhat from the schizophrenia literature, sleep deprivation additionally disrupted PS control. Sleep deprivation thus represents a promising but possibly unspecific experimental model that may be helpful to further improve our understanding of the underlying mechanisms in the pathophysiology of psychosis and aid the development of antipsychotic and pro-cognitive drugs.

RP5063, an atypical antipsychotic drug with a unique pharmacologic profile, improves declarative memory and psychosis in mouse models of schizophrenia

Various types of atypical antipsychotic drugs (AAPDs) modestly improve the cognitive impairment associated with schizophrenia (CIAS). RP5063 is an AAPD with a diverse and unique pharmacology, including partial agonism at dopamine (DA) D₂, D₃, D₄, serotonin (5-HT)_1A, and 5-HT_2A receptors (Rs), full agonism at α₄β₂ nicotinic acetylcholine (ACh)R (nAChR), and antagonism at 5-HT_2B, 5-HT₆, and 5-HT₇Rs. Most atypical APDs are 5-HT_2A inverse agonists. The efficacy of RP5063 in mouse models of psychosis and episodic memory were studied. RP5063 blocked acute phencyclidine (PCP)-as well as amphetamine-induced hyperactivity, indicating antipsychotic activity. Acute administration of RP5063 significantly reversed subchronic (sc)PCP-induced impairment in novel object recognition (NOR), a measure of episodic memory, but not reversal learning, a measure of executive function. Co-administration of a sub-effective dose (SED) of RP5063 with SEDs of a 5-HT₇R antagonist, a 5-HT_1BR antagonist, a 5-HT_2AR inverse agonist, or an α₄β₂ nAChR agonist, restored the ability of RP5063 to ameliorate the NOR deficit in scPCP mice. Pre-treatment with a 5-HT_1AR, a D₄R, antagonist, but not an α₄β₂ nAChR antagonist, blocked the ameliorating effect of RP5063. Further, co-administration of scRP5063 prior to each dose of PCP prevented the effect of PCP to produce a deficit in NOR for one week. RP5063, given to scPCP-treated mice for one week restored NOR for one week only. Acute administration of RP5063 significantly increased cortical DA efflux, which may be critical to some of its cognitive enhancing properties. These results indicate that RP5063, by itself, or as an adjunctive treatment has a multifaceted basis for improving some cognitive deficits associated with schizophrenia.

Electroconvulsive Therapy for Agitation in Schizophrenia: Metaanalysis of Randomized Controlled Trials

Background

Agitation poses a significant challenge in the treatment of schizophrenia. Electroconvulsive therapy (ECT) is a fast, effective and safe treatment for a variety of psychiatric disorders, but no meta-analysis of ECT treatment for agitation in schizophrenia has yet been reported.

Aims

To systematically evaluate the efficacy and safety of ECT alone or ECT-antipsychotics (APs) combination for agitation in schizophrenia.

Methods

Systematic literature search of randomized controlled trials (RCTs) was performed. Two independent evaluators selected studies, extracted data about outcomes and safety with available data, conducted quality assessment and data synthesis. The Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) was used to judge the level of the overall evidence of main outcomes.

Results

Seven RCTs from China, including ECT alone (4 RCTs with 5 treatment arms, n=240) and ECT-APs combination (3 RCTs, n=240), were identified. Participants in the studies were on average 34.3(4.5) years of age and lasted an average of 4.3(3.1) weeks of treatment duration. All 7 RCTs were non-blinded, and were rated as low quality based on Jadad scale. Meta-analysis of the pooled sample found no significant difference in the improvement of the agitation sub-score of the Positive and Negative Syndrome Scale (PANSS) when ECT alone (weighted mean difference=-0.90, (95% confidence interval (CI): -2.91, 1.11), p=0.38) or ECT-APs combination (WMD=-1.34, (95%CI: -4.07, 1.39), p=0.33) compared with APs monotherapy. However, ECT alone was superior to APs monotherapy regarding PANSS total score (WMD=-7.13, I²=0%, p=0.004) and its excitement sub-score (WMD=-1.97, p<0.0001) as well as the PANSS total score at 14 days (WMD=-7.13, I²=0%, p=0.004) and its excitement sub-score at 7 and 14 days (WMD=-1.97 to -1.92, p=0.002 to 0.0001) after ECT. The ECT-APs combination was superior to APs monotherapy with respect to the PANSS total score at treatment endpoint (WMD=-10.40, p=0.03) and 7 days (WMD=-5.01, p=0.02). Headache (number-needed-to-harm (NNH)=3, 95%CI=2-4) was more frequent in the ECT alone group compared to AP monotherapy. According to the GRADE approach, the evidence levels of main outcomes were rated as ‘‘very low’’ (37.5%) and “low” (50%).

Conclusion

Pooling of the data based on 7 RCTs from China found no advantage of ECT alone or ECT-APs combination in the treatment of agitation related outcomes in schizophrenia patients. However, ECT alone or ECT-APs combination were associated with significant reduction in the PANSS total score. High-quality RCTs are needed to confirm the current interpretations.

Discovery of G Protein-Biased D2 Dopamine Receptor Partial Agonists

Biased ligands (also known as functionally selective ligands) of G protein-coupled receptors are valuable tools for dissecting the roles of G protein-dependent and independent signaling pathways in health and disease. Biased ligands have also been increasingly pursued by the biomedical community as promising therapeutics with improved efficacy and reduced side effects compared with unbiased ligands. We previously discovered first-in-class β-arrestin-biased agonists of dopamine D2 receptor (D2R) by extensively exploring multiple regions of aripiprazole, a balanced D2R agonist. In our continuing efforts to identify biased agonists of D2R, we unexpectedly discovered a G protein-biased agonist of D2R, compound 1, which is the first G protein-biased D2R agonist from the aripiprazole scaffold. We designed and synthesized novel analogues to explore two regions of 1 and conducted structure-functional selectivity relationship (SFSR) studies. Here we report the discovery of 1, findings from our SFSR studies, and characterization of novel G protein-biased D2R agonists.

ITI-007 in the treatment of schizophrenia: from novel pharmacology to clinical outcomes

ITI-007 is an investigational drug being developed for schizophrenia and other neuropsychiatric/neurodegenerative diseases. ITI-007 has a unique pharmacological profile, combining potent 5-HT2a receptor antagonism with cell-type-specific dopamine and glutamate receptor modulation, plus serotonin reuptake inhibition. At dopamine-D2 receptors, ITI-007 acts as a post-synaptic antagonist and pre-synaptic partial agonist. Additionally, ITI-007 stimulates phosphorylation of glutamatergic NMDA-NR2B receptors, downstream of dopamine-D1 receptor intracellular signaling. Based on a large, placebo and risperidone controlled, Phase-II trial, ITI-007 60 mg was shown to be effective in reducing symptoms in patients with acutely exacerbated schizophrenia. The antipsychotic efficacy of ITI-007 60 mg in this patient population was confirmed in a recently completed Phase III study. ITI-007 was associated with minimal safety risk compared to risperidone (Phase II study) or placebo (both studies) for neuromotor disturbances, prolactin changes, weight gain and metabolic abnormalities. A second 6-week, placebo and risperidone-controlled Phase-III trial in acutely exacerbated schizophrenia is ongoing.

Glutamatergic agents for schizophrenia: current evidence and perspectives

Suboptimal outcomes in schizophrenia are a consequence of lacking insight into the etiology, biomarkers and treatment-relevant subgroups, the therapeutic restriction to dopaminergic-modulating antipsychotics that fail to significantly improve negative and cognitive symptoms, non-adherence, and, in the case of treatment-resistance, the underutilization of clozapine. Evidence suggests additional, extra-dopaminergic abnormalities in amino acid neurotransmission, particularly the glutamatergic system. Antidopaminergic antipsychotics modulate this system on several levels, as do mood stabilizers, including lamotrigine, topiramate and pregabaline. Recently, agonists at metabotropic glutamate receptors and glycine uptake inhibitors failed in large placebo-controlled trials for schizophrenia. Problems to overcome for successfully leveraging glutamatergic agents for schizophrenia are patient selection, focus on positive symptoms and late disease stages, and dose-response relationships. Because glutamate guides processes of brain development and maturation, clinical research should focus on the at-risk mental state or first-episode psychosis, address cognition and negative symptoms and use monotherapy designs in parallel to augmentation strategies.

Cognitive impairment in schizophrenia: the great unmet need

Cognitive impairment in schizophrenia is present in almost all persons with the disorder and can be a substantial obstacle to efforts in the recovery process. In clinical research, cognition is assessed through neuropsychological testing as well as by different types of structured instruments focusing on function. Although nonpharmacological interventions such as cognitive remediation have been therapeutic, particularly in combination with vocational rehabilitation and supported employment, these modalities are not always easy to access. Pharmacological interventions are in development and have principally focused on the dopamine, glutamate, and acetylcholine neurotransmitter systems, aiming to target the dorsolateral prefrontal cortex and its interactions with other brain regions.

Schizophrenia

Schizophrenia is a chronic psychiatric disorder with a heterogeneous genetic and neurobiological background that influences early brain development, and is expressed as a combination of psychotic symptoms - such as hallucinations, delusions and disorganization - and motivational and cognitive dysfunctions. The mean lifetime prevalence of the disorder is just below 1%, but large regional differences in prevalence rates are evident owing to disparities in urbanicity and patterns of immigration. Although gross brain pathology is not a characteristic of schizophrenia, the disorder involves subtle pathological changes in specific neural cell populations and in cell-cell communication. Schizophrenia, as a cognitive and behavioural disorder, is ultimately about how the brain processes information. Indeed, neuroimaging studies have shown that information processing is functionally abnormal in patients with first-episode and chronic schizophrenia. Although pharmacological treatments for schizophrenia can relieve psychotic symptoms, such drugs generally do not lead to substantial improvements in social, cognitive and occupational functioning. Psychosocial interventions such as cognitive-behavioural therapy, cognitive remediation and supported education and employment have added treatment value, but are inconsistently applied. Given that schizophrenia starts many years before a diagnosis is typically made, the identification of individuals at risk and those in the early phases of the disorder, and the exploration of preventive approaches are crucial.

Weight gain and obesity in schizophrenia: epidemiology, pathobiology, and management

OBJECTIVE

To review recent advances in the epidemiology, pathobiology, and management of weight gain and obesity in patients with schizophrenia and to evaluate the extent to which they should influence guidelines for clinical practice.

METHOD

A Medline literature search was performed to identify clinical and experimental studies published in 2005-2014 decade.

RESULTS

Weight gain and obesity increase the risk of adult-onset diabetes mellitus and cardiovascular disorders, non-adherence with pharmacological interventions, quality of life, and psychiatric readmissions. The etiology includes adverse effects of antipsychotics, pretreatment/premorbid genetic vulnerabilities, psychosocial and socioeconomic risk factors, and unhealthy lifestyle. Patients with schizophrenia have higher intake of calories in the form of high-density food and lower energy expenditure. The inverse relationship between baseline body mass index and antipsychotic-induced weight gain is probably due to previous antipsychotic exposure. In experimental models, the second-generation antipsychotic olanzapine increased the orexigenic stimulation of hypothalamic structures responsible for energy homeostasis.

CONCLUSION

The management of weight gain and obesity in patients with schizophrenia centers on behavioural interventions using caloric intake reduction, dietary restructuring, and moderate-intensity physical activity. The decision to switch antipsychotics to lower-liability medications should be individualized, and metformin may be considered for adjunctive therapy, given its favorable risk-benefit profile.

Treatment of clozapine-associated weight gain: a systematic review

PURPOSE

Clozapine is an antipsychotic drug with superior efficacy in treatment-resistant schizophrenia. Clozapine is associated with a low likelihood of extrapyramidal symptoms and other neurological side-effects but a high propensity to induce weight gain and general metabolic dysregulation. Various pharmacological and behavioral treatment approaches for reducing clozapine-associated weight gain exist in the literature; however, there are currently no clear clinical guidelines as to which method is preferred. The aim of the current review is to systematically summarize studies that have studied both pharmacological and non-pharmacological interventions to attenuate or reverse clozapine-associated weight gain.

METHODS

A systematic review of EMBASE and MEDLINE databases of all articles published prior to January 2014 was conducted. Seventeen studies were identified as meeting inclusion criteria and included in the review.

RESULTS

Aripiprazole, fluvoxamine, metformin, and topiramate appear to be beneficial; however, available data are limited to between one and three randomized controlled trials per intervention. Orlistat shows beneficial effects, but in males only. Behavioral and nutritional interventions also show modest effects on decreasing clozapine-associated weight gain, although only a small number of such studies exist.

CONCLUSIONS

While a number of pharmacological interventions can produce modest weight loss, each may be associated with negative side effects, which should be considered before beginning treatment. Given the pressing need to improve cardiometabolic health in most clozapine-treated patients, substantially more research is needed to develop sound clinical practice guidelines for the treatment of clozapine-associated weight gain.

Thinking and acting beyond the positive: the role of the cognitive and negative symptoms in schizophrenia

Since currently available antipsychotic medications predominantly treat hallucinations, delusions, disorganized thoughts and behavior, and related agitation/aggression, attention has traditionally been focused on managing positive symptoms. However, prominent negative symptoms and clinically relevant cognitive impairment affect approximately 40% and 80% of people with schizophrenia, respectively. Moreover, negative and cognitive symptoms are closely related to functional outcomes, and contribute substantially to the overall illness burden. Therefore, approaches to describe, measure, and manage these symptom domains are relevant. This article summarizes the phenomenology, prevalence, assessment, and treatment of negative and cognitive symptoms in patients with schizophrenia, including pharmacologic and nonpharmacologic management strategies that can be used in clinical care now, as well as pharmacologic approaches that are being tested. Currently, no approved treatments targeting negative or cognitive symptomatology in schizophrenia are available. It is hoped that progress in the understanding of the neurobiology of these important symptom domains of schizophrenia will help develop effective treatment strategies in the future. However, until this goal is achieved, clinicians should avoid therapeutic nihilism. Rather, the severity and impact of negative and cognitive symptoms should be determined, quantified, and monitored. Further, psychosocial treatments have shown therapeutic benefits. Thus, cognitive behavioral therapy, cognitive remediation, social skills training, and computer-assisted training programs should be offered in conjunction with antipsychotic treatment. Several non-antipsychotic augmentation strategies can be tried off-label. Treatment plans that incorporate currently available management options for negative and cognitive symptomatology in patients with schizophrenia should be adapted over time and based on the individual's needs, with the aim to enhance overall outcomes.