Adjunctive second-generation antipsychotics for specific symptom domains of schizophrenia resistant to clozapine: A meta-analysis

Efficacy and safety of clozapine in treatment-resistant psychotic patients with DiGeorge syndrome (22q11.2 deletion syndrome): a case series

Neuropsychiatric disorders are common manifestations in 22q11.2 deletion syndrome (22q11.2DS-DiGeorge Syndrome). Although many patients with 22q11.2DS receive antipsychotic treatment for psychotic disorders, little is known about the safety and tolerability of antipsychotics in 22q11.2DS and resistant psychosis. The aim of this case series is to describe the effectiveness as well as safety and tolerability profile coming from the real-world observation of three clinical cases affected by 22q11.2DS and treatment-resistant psychosis. We administered the following tests: the Columbia Suicide Severity Rating Scale, the Hamilton Rating Scale for Anxiety, the Positive and Negative Severity Scale, the Clinical Global Impression-Severity Scale, the Yale-Brown Obsessive-Compulsive Scale, the Beck Depression Inventory and the Beck Hopelessness Scale. All these questionnaires were administered at the first visit (T0), and then 3 (T1) 6 (T2) and 12 months after (T3). We observed a clinical improvement that remained stable at 12 months. Furthermore, in our patients, the clinical effectiveness was achieved with a very low dose of clozapine (<150 mg/day) concerning the standard dose used in idiopathic schizophrenia (>300 mg/day to 600 mg/day).

Comparative Study of the Efficacy and Side Effects of Brand-Name and Generic Clozapine for Long-Term Maintenance Treatment Among Korean Patients With Schizophrenia: A Retrospective Naturalistic Mirror-Image Study

OBJECTIVE

Clozapine is considered the most reliable drug for treatment-resistant schizophrenia. In 2014, a generic formulation of clozapine (Clzapine) was introduced in Korea. This study was performed to provide clinical information regarding the use of clozapine and to compare efficacy and tolerability when converting from the brand-name formulation (Clozaril) to the generic formulation during longterm maintenance treatment among Korean patients with schizophrenia.

METHODS

This mirror-image study retrospectively investigated the electronic medical records of patients who had switched from Clozaril to Clzapine with a ≥1-year duration for each formulation. Clinical data were collected, including information regarding clozapine use, psychiatric hospitalization, co-medications, and blood test findings. Data before and after the switch were compared using paired t-tests.

RESULTS

Among 332 patients, the mean 1-year dosages were 233.32±149.35 mg/day for Clozaril and 217.36±136.66 mg/day for Clzapine. The mean clozapine concentration-to-dose ratios were similar before and after the switch (Clozaril, 1.33±0.68; Clzapine, 1.26±0.80). Switching from Clozaril to Clzapine resulted in no significant differences in the hospitalization rate, hospitalization duration, or laboratory findings (liver function parameters, serum cholesterol level, and serum glucose level). Equivalent doses of co-prescribed antidepressants were decreased, but concomitant medications otherwise showed no significant differences.

CONCLUSION

Clinical efficacy and tolerability appear comparable when switching to Clzapine during clozapine maintenance treatment. This study offers descriptive real-world clinical insights into clozapine maintenance treatment in Korea, thereby providing patients with more treatment options and contributing to the development of maintenance guidelines tailored to the Korean population.

Possible mechanism of schizophrenia origin by excess GABA and synaptic pruning

Schizophrenia is a psychotic disorder that affects approximately 1% of the global population. However, the etiology of this illness remains a subject of debate. One of the proposed mechanisms underlying schizophrenia is the synaptic pruning mediated by microglia in the brains of individuals with schizophrenia, although the precise mechanisms of this process remain elusive. In this regard, we propose that the potential development of the disease stems from both a genetic predisposition leading to an excessive production of GABAergic neurons and an exaggerated effort to maintain the E/I (excitation/inhibition) balance in the brain.

Augmentation strategies for clozapine resistance: a systematic review and meta-analysis

BACKGROUND

Several augmentation strategies have been used to improve symptomatology in patients not adequately responding to clozapine. Several randomised controlled trials (RCTs) have evaluated the efficacy of different strategies to augment clozapine. This systematic review and meta-analysis reviewed the available RCTs that have evaluated the clinical efficacy of various pharmacological agents, non-pharmacological strategies (occupational therapy, cognitive behaviour therapy), and somatic treatment [electroconvulsive therapy (ECT), repetitive transcranial magnetic stimulation, etc.)] as augmenting agents to clozapine.

METHODS

Data were extracted using standard procedures, and risk of bias was evaluated. Effect sizes were computed for the individual studies.

RESULTS

Forty-five clinical trials were evaluated. The pooled effect size for various antipsychotic medications was 0.103 (95% CI: 0.288-0.493, p < 0.001); when the effect size was evaluated for specific antipsychotics for which more than one trial was available, the effect size for risperidone was -0.27 and that for aripiprazole was 0.57. The effect size for lamotrigine was 0.145, and that for topiramate was 0.392. The effect size for ECT was 0.743 (CI: 0.094-1.392). Risk of bias was low (mean Jadad score - 3.93). Largest effect sizes were seen for mirtazapine (effect size of 5.265). Most of the studies can be considered underpowered and limited by small sample sizes.

CONCLUSIONS

To conclude, based on the findings of the present systematic review and meta-analysis, it can be said that compared to other treatment strategies, clozapine non-responsive patients respond maximum to mirtazapine followed by ECT.

Third-generation antipsychotics in patients with schizophrenia and non-responsivity or intolerance to clozapine regimen: What is the evidence?

Clozapine is considered « the golden standard » for the management of treatment-resistant schizophrenia, but many patients do not present adequate responsivity even to this antipsychotic. If we add the need to strictly monitor the hematologic and cardiometabolic adverse events during each clozapine trial and the difficulty of preserving therapeutic adherence in patients with low insight, residual negative/positive symptoms, or economic challenges, then the necessity of exploring alternative interventions for these patients becomes obvious. Also, in case of intolerance to clozapine or where clozapine did not induce remission, clinicians have to find new ways to help their patients. Switching to other antipsychotics or using these agents as add-ons to clozapine are the main interventions explored in this review, for patients with schizophrenia resistant to clozapine (ultra-resistant schizophrenia, URS). When clozapine intolerance is detected, conversion to another antipsychotic with distinct pharmacologic properties or formulation (e.g., long-acting intramuscular injectable agents, LAI) may be a useful option. Third-generation antipsychotics (TGA) have been selected for their distinct pharmacodynamically profile, which allows, at a theoretical level, their use in combination with clozapine. This narrative review is based on searching four electronic databases, that retrieved 19 primary and secondary reports on aripiprazole (seven case reports or case series presenting 24 patients; nine clinical trials, and three systematic reviews/meta-analyses), two primary reports on brexpiprazole (case report and case series, N = 3 patients), and six primary reports on cariprazine (case reports and case series, N = 14 patients). Based on the information collected from these reports, which included oral and LAI formulations, the TGA most supported by evidence for the augmentation of clozapine is aripiprazole (high-and medium-quality data), followed by cariprazine (low-quality data). Brexpiprazole has not yet been systematically explored for this indication, and in the case of lumateperone, no report could be found. The efficacy of aripiprazole and cariprazine was supported in the domains of positive, negative, and general symptoms, and aripiprazole may positively impact the metabolic profile in patients with URS. Also, adding TGA may lead to a decrease in the dose of clozapine concomitantly administered. More data derived from good quality research are needed in order to confirm the circumstances of TGAs recommendation in patients with URS, either as monotherapy, or added to clozapine.

Clozapine resistant schizophrenia: Newer avenues of management

About 40%-70% of the patients with treatment-resistant schizophrenia have a poor response to adequate treatment with clozapine. The impact of clozapine-resistant schizophrenia (CRS) is even greater than that of treatment resistance in terms of severe and persistent symptoms, relapses and hospitalizations, poorer quality of life, and healthcare costs. Such serious consequences often compel clinicians to try different augmentation strategies to enhance the inadequate clozapine response in CRS. Unfortunately, a large body of evidence has shown that antipsychotics, antidepressants, mood stabilizers, electroconvulsive therapy, and cognitive-behavioural therapy are mostly ineffective in augmenting clozapine response. When beneficial effects of augmentation have been found, they are usually small and of doubtful clinical significance or based on low-quality evidence. Therefore, newer treatment approaches that go beyond the evidence are needed. The options proposed include developing a clinical consensus about the augmentation strategies that are most likely to be effective and using them sequentially in patients with CRS. Secondly, newer approaches such as augmentation with long-acting antipsychotic injections or multi-component psychosocial interventions could be considered. Lastly, perhaps the most effective way to deal with CRS would be to optimize clozapine treatment, which might prevent clozapine resistance from developing. Personalized dosing, adequate treatment durations, management of side effects and non-adherence, collaboration with patients and caregivers, and addressing clinician barriers to clozapine use are the principal ways of ensuring optimal clozapine treatment. At present, these three options could the best way to manage CRS until research provides more firm directions about the effective options for augmenting clozapine response.

A Repeated Time-to-Positive Symptoms Improvement among Malaysian Patients with Schizophrenia Spectrum Disorders Treated with Clozapine

Clozapine remains the drug of choice for resistant schizophrenia. However, its dose-response relationship is still controversial. The current investigation aimed to develop a repeated time-to-positive symptoms improvement following the onset of clozapine treatment in Malaysian schizophrenia spectrum disorder patients. Data from patients’ medical records in the Psychiatric Clinic, Penang General Hospital, were retrospectively analyzed. Several parametric survival models were evaluated using nonlinear mixed-effect modeling software (NONMEM 7.3.0). Kaplan–Meier-visual predictive check (KM-VPC) and sampling-importance resampling (SIR) methods were used to validate the final model. A total of 116 patients were included in the study, with a mean follow-up of 306 weeks. Weibull hazard function best fitted the data. The hazard of positive symptoms improvement decreased 4% for every one-year increase in age over the median of 41 years (adjusted hazard ratio (aHR), 0.96; 95% confidence intervals (95% CI), (0.93–0.98)). However, patients receiving a second atypical antipsychotic agent had four-folds higher hazard (aHR, 4.01; 95% CI, (1.97–7.17)). The hazard increased 2% (aHR, 1.02; 95% CI, (1.01–1.03)) for every 1 g increase in the clozapine six months cumulative dose over the median of 34 g. The developed model provides essential information on the hazard of positive symptoms improvement after the first clozapine dose administration, including modifiable predictors of high clinical importance.

Novel Treatment for the Most Resistant Schizophrenia: Dual Activation of NMDA Receptor and Antioxidant

Clozapine has been regarded as the last-line antipsychotic agent for patients with refractory schizophrenia. However, many patients remain unresponsive to clozapine, referred to as "clozapineresistant", "ultra-treatment-resistant", or remain in incurable state. There has been no convincing evidence for augmentation on clozapine so far. Novel treatments including numerous N-methyl-Daspartate (NMDA) receptor (NMDAR) enhancers, such as glycine, D-serine, D-cycloserine, and Nmethylglycine (sarcosine) failed in clinical trials. Earlier, the inhibition of D-amino acid oxidase (DAAO) that may metabolize D-amino acids and activate NMDAR has been reported to be beneficial for patients with schizophrenia receiving antipsychotics except for clozapine. A recent randomized, double-blind, placebo-controlled clinical trial found that add-on sodium benzoate, a DAAO inhibitor, improved the clinical symptoms in patients with clozapine- resistant schizophrenia, possibly through DAAO inhibition (and thereby NMDAR activation) and antioxidation as well; additionally, sodium benzoate showed no obvious side effects, indicating that the treatment is safe at doses up to 2 g per day for 6 weeks. More studies are warranted to elucidate the mechanisms of sodium benzoate for the treatment of schizophrenia and the etiology of this severe brain disease. If the finding can be reconfirmed, this approach may bring new hope for the treatment of the most refractory schizophrenia. This review summarizes the current status of clinical trials and related mechanisms for treatmentresistant, especially, clozapine-resistant schizophrenia. The importance of understanding the molecular circuit switches is also highlighted which can restore brain function in patients with schizophrenia. Future directions in developing better treatments for the most difficult to cure schizophrenia are also discussed.

Possible pharmacogenetic factors in clozapine treatment failure: a case report

There is still much to learn about the predictors of therapeutic response in psychiatry, but progress is gradually being made and precision psychiatry is an exciting and emerging subspeciality in this field. This is critically important in the treatment of refractory psychotic disorders, where clozapine is the only evidence-based treatment but only about half the patients experience an adequate response. In this case report, we explore the possible biological mechanisms underlying treatment failure and discuss possible ways of improving clinical outcomes. Further work is required to fully understand why some patients fail to respond to the most effective treatment in refractory schizophrenia. Therapeutic drug monitoring together with early pharmacogenetic testing may offer a path for some patients with refractory psychotic symptoms unresponsive to clozapine treatment.

Epidemiology of schizophrenia and its management over 8-years period using real-world data in Spain

BACKGROUND

Real-World Data (RWD) studies provide important insights in disease epidemiology, in real clinical populations, with long follow-up periods. The aim of the present study was to describe the epidemiology of schizophrenia spectrum disorders (SD) during an 8-year period in Spain.

METHODS

A retrospective cohort of subjects aged 15 to 64 years was followed-up using electronic healthcare databases of the Valencia region (2008-2015). SD cases included outpatient and inpatient settings (ICD 9 codes 295.XX). Prevalence of SD was assessed. Incidence rate (IR) in the subpopulation aged between 15 and 34 years was also provided. Healthcare utilization (HCU) rates, including outpatient, specialists, hospitalizations and antipsychotic dispensations were estimated.

RESULTS

The cohort included 3,976,071 subjects; 24,749 of them had a prevalent diagnosis of SD. The overall prevalence for SD was 6.2 per 1000 persons. SD were 76% more prevalent in men than women. IR in the subpopulation aged between 15 and 34 years was 50.25 per 100,000 persons years and was more than 2 times higher for men than for women. 83.4% of the overall outpatient visits from the cohort of patients were related to SD. The 21,095 overall hospitalizations with the SD code resulted in 286,139 days of hospitalization, with a median of 4 days (IQR: 1.6-9.2) per person-year. 93.2% of subjects diagnosed with SD were ever treated with some antipsychotic drug during the study period, and 70% of the patients were ever treated with antipsychotic polypharmacy.

CONCLUSIONS

This large population-based study using RWD provides novel and recent information SD in a southern European country. The prevalence and IR of SD showed is greater than previously published and higher in men than in women. The fact of having used a large arsenal of electronic data (including outpatient and inpatient) for 8 years may have influenced. SD represents high burden and healthcare utilization. Contrary to guidelines recommendations the majority of patients were ever treated with antipsychotic polypharmacy.

The role of astrocytic glutamate transporters GLT-1 and GLAST in neurological disorders: Potential targets for neurotherapeutics

Glutamate is the primary excitatory neurotransmitter in the central nervous system (CNS) which initiates rapid signal transmission in the synapse before its re-uptake into the surrounding glia, specifically astrocytes. The astrocytic glutamate transporters glutamate-aspartate transporter (GLAST) and glutamate transporter-1 (GLT-1) and their human homologs excitatory amino acid transporter 1 (EAAT1) and 2 (EAAT2), respectively, are the major transporters which take up synaptic glutamate to maintain optimal extracellular glutamic levels, thus preventing accumulation in the synaptic cleft and ensuing excitotoxicity. Growing evidence has shown that excitotoxicity is associated with various neurological disorders, including amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), Parkinson's disease (PD), manganism, ischemia, schizophrenia, epilepsy, and autism. While the mechanisms of neurological disorders are not well understood, the dysregulation of GLAST/GLT-1 may play a significant role in excitotoxicity and associated neuropathogenesis. The expression and function of GLAST/GLT-1 may be dysregulated at the genetic, epigenetic, transcriptional or translational levels, leading to high levels of extracellular glutamate and excitotoxicity. Consequently, understanding the regulatory mechanisms of GLAST/GLT-1 has been an area of interest in developing therapeutics for the treatment of neurological disorders. Pharmacological agents including β-lactam antibiotics, estrogen/selective estrogen receptor modulators (SERMs), growth factors, histone deacetylase inhibitors (HDACi), and translational activators have shown significant efficacy in enhancing the expression and function of GLAST/GLT-1 and glutamate uptake both in vitro and in vivo. This comprehensive review will discuss the regulatory mechanisms of GLAST/GLT-1, their association with neurological disorders, and the pharmacological agents which mediate their expression and function. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.

Clozapine augmentation strategies

Clozapine is established as the gold standard for antipsychotic treatment of patients suffering from treatment-resistant schizophrenia. Over virtually 3 decades, the level of inadequate response to clozapine was found to range from 40% to 60%. A heightened interest developed in the augmentation of clozapine to try to achieve response or maximize partial response. A large variety of drug groups have been investigated. This article focuses on the meta-analyses of these trials to discover reasonable evidence-based approaches to the management of patients not responding to clozapine.

Switching to antipsychotic monotherapy vs. staying on antipsychotic polypharmacy in schizophrenia: A systematic review and meta-analysis

BACKGROUND

While recent meta-analyses have reported the superiority of antipsychotic polypharmacy (APP) over antipsychotic monotherapy (APM) in schizophrenia, switching to APM can be beneficial in terms of side effects. To determine whether patients receiving APP should switch to APM or stay on APP, we conducted a systematic review and meta-analysis.

METHODS

Randomized controlled trials (RCTs) examining a switch from APP to APM vs. staying on APP were systematically selected from a previous meta-analysis comparing APP with APM in patients with schizophrenia. In addition, we conducted an updated systematic literature search using MEDLINE, Embase, and Cochrane Central Register of Controlled Trials. Data on study discontinuation, relapse, psychopathology, neurocognition, extrapyramidal symptoms, and body weight/body mass index (BMI) were extracted and synthesized.

RESULTS

A total of 6 RCTs involving 341 patients were included. All studies examined a switch from 2 antipsychotic agents to a single agent. Clozapine-treated patients were included in 3 studies. There was a significant difference in study discontinuation due to all causes in favor of staying on APP (N = 6, n = 341, RR = 2.28, 95% CI = 1.50-3.46, P < 0.001). There were no significant differences in relapse, any psychopathology, neurocognition, extrapyramidal symptoms, or body weight/BMI between the 2 groups. The quality of evidence was low to very low.

CONCLUSIONS

The findings suggest that clinicians should closely monitor patient condition when switching to APM after receiving 2 antipsychotics. Given the low to very low overall quality of the evidence, the findings should be considered preliminary and inconclusive.