An open-label, positron emission tomography study of the striatal D2/D3 receptor occupancy and pharmacokinetics of single-dose oral brexpiprazole in healthy participants

Optimisation of pharmacotherapy in psychiatry through therapeutic drug monitoring, molecular brain imaging and pharmacogenetic tests: focus on antipsychotics

BACKGROUND

For psychotic disorders (i.e. schizophrenia), pharmacotherapy plays a key role in controlling acute and long-term symptoms. To find the optimal individual dose and dosage strategy, specialized tools are used. Three tools have been proven useful to personalize drug treatments: therapeutic drug monitoring (TDM) of drug levels, pharmacogenetic testing (PG), and molecular neuroimaging.

METHODS

In these Guidelines, we provide an in-depth review of pharmacokinetics, pharmacodynamics, and pharmacogenetics for 50 antipsychotics. Over 30 international experts in psychiatry selected studies that have measured drug concentrations in the blood (TDM), gene polymorphisms of enzymes involved in drug metabolism, or receptor/transporter occupancies in the brain (positron emission tomography (PET)).

RESULTS

Study results strongly support the use of TDM and the cytochrome P450 (CYP) genotyping and/or phenotyping to guide drug therapies. Evidence-based target ranges are available for titrating drug doses that are often supported by PET findings.

CONCLUSION

All three tools discussed in these Guidelines are essential for drug treatment. TDM goes well beyond typical indications such as unclear compliance and polypharmacy. Despite its enormous potential to optimize treatment effects, minimize side effects and ultimately reduce the global burden of diseases, personalized drug treatment has not yet become the standard of care in psychiatry.

Investigating the Effectiveness of Brexpiprazole in Subjects with Schizophrenia Spectrum Illness and Co-Occurring Substance Use Disorder: A Prospective, Multicentric, Real-World Study

BACKGROUND

Dual disorders (DDs) involve the coexistence of a substance use disorder (SUD) with another mental illness, often from the psychotic and affective categories. They are quite common in clinical practice and present significant challenges for both diagnosis and treatment. This study explores the effectiveness of brexpiprazole, a third-generation antipsychotic, in an Italian sample of individuals diagnosed with schizophrenia spectrum disorder and a comorbid SUD.

METHODS

Twenty-four patients, diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) and enrolled in several Italian hospitals, underwent a psychometric assessment at baseline (T0) and one month (T1) after starting brexpiprazole treatment administered at a mean dosage of 2 mg/day.

RESULTS

Brexpiprazole demonstrated significant reductions in psychopathological burden (Positive and Negative Syndrome Scale/PANSS total score: p < 0.001). Positive (p = 0.003) and negative (p = 0.028) symptoms, substance cravings (VAS craving: p = 0.039), and aggression (MOAS scale: p = 0.003) were notably reduced. Quality of life improved according to the 36-item Short Form Health Survey (SF-36) subscales (p < 0.005).

CONCLUSIONS

This study provides initial evidence supporting brexpiprazole's efficacy and safety in this complex patient population, with positive effects not only on psychopathology and quality of life, but also on cravings. Further studies involving larger cohorts of subjects and extended follow-up periods are needed.

Brexpiprazole in patients with schizophrenia with or without substance use disorder: an observational study

Background

Partial dopamine D2 receptor agonists are used for psychotic symptoms in adults with schizophrenia spectrum disorders. Recently, interest surged for partial dopamine D2 receptor agonists in substance use disorders (SUDs). Since it is believed that SUDs decrease the efficacy of pharmacotherapy of underlying psychiatric disorders, we tested the efficacy of the partial D2 agonist brexpiprazole in patients with schizophrenia who were either comorbid with a SUD (SUD group) or not comorbid (non-SUD) to assess treatment response and the effect of brexpiprazole on substance craving in SUD.

Methods

We included patients with DSM-5/DSM-5-TR schizophrenia (using SCID-5-CV) aged 18-66 years with either comorbid SUD or non-SUD to treat with brexpiprazole 4 mg/day for 6 months during February-October 2022. Patients were assessed with the Clinical Global Impressions-Severity (CGI-S) scale, the 24-item Brief Psychiatric Rating Scale (BPRS), and the Positive And Negative Syndrome Scale (PANSS) at baseline, weekly for the first 2 months and monthly for the next four. Furthermore, we assessed substance craving in SUD with a visual analog scale for craving (VAScrav) at the same timepoints.

Results

The total sample was 86 (85 analysable) 18- to 64-year-old (mean 39.32 ± 14.09) patients with schizophrenia [51 men (59.3%) and 35 women (40.7%)], of whom 48 SUD (55.8%) (37 men and 11 women) and 38 non-SUD (44.2%) (14 men and 24 women). No serious or persistent adverse events developed over the study period, but one patient dropped out for subjective akathisia. Results indicated the main effects of time with improvements over the course of the study for CGI-S, BPRS, and PANSS in both SUD and non-SUD groups and the entire sample, and for VAScrav in SUD. Brexpiprazole was associated with similar significant improvements in both groups at the 6 month endpoint compared to baseline.

Conclusion

Treatment with brexpiprazole for 6 months improved psychotic symptoms in patients with schizophrenia, independently from whether they belonged to the SUD or the non-SUD group; hence, SUD comorbidity did not confer treatment resistance to brexpiprazole. Furthermore, in the SUD group, we observed reduced substance craving.

Can brexpiprazole be switched safely in patients with schizophrenia and dopamine supersensitivity psychosis? A retrospective analysis in a real-world clinical practice

BACKGROUND

Several studies have reported that a switch to the dopamine partial agonist (DPA) aripiprazole (ARP), especially when the switch is abrupt, is likely to fail and sometimes worsen psychosis in schizophrenia patients already under high-dose antipsychotic treatment. Such a switching failure is speculated to be related to be the dopamine supersensitivity state. The risks of switching to the DPA brexpiprazole (BREX) have not been reported.

AIMS AND METHODS

We retrospectively analyzed the cases of 106 patients with schizophrenia to identify any factors related to the success or failure of switching to BREX.

RESULTS

The comparison between the patients with dopamine supersensitivity psychosis (n = 44) and those without (n = 62) revealed no significant difference in the switching failure judged at the sixth week. A comparison of the patients with successful switching (n = 80) and those who failed (n = 26) revealed that patients with treatment-resistant schizophrenia (TRS) were significantly more likely to fail. A logistic regression analysis also revealed that patients with past failure of switching to ARP are likely to succeed in switching to BREX. The 2-year follow-up of the patients with successful switching to BREX suggested that the patients who were treated with BREX, even temporarily, experienced some improvement in their Global Assessment of Functioning and Clinical Global Impression-Severity scores.

CONCLUSIONS

Overall, the results indicate that patients with schizophrenia can be switched more safely to BREX compared to ARP. However, the failure of switching to BREX could be higher in patients with TRS, and thus, starting BREX treatment in refractory patients warrants careful monitoring.

An exploratory database study of factors influencing the continuation of brexpiprazole treatment (prescription) in patients with schizophrenia using information from psychiatric electronic medical records processed with natural language processing

Using natural language processing (NLP) technology to analyze and organize textual information in psychiatric electronic medical records can identify undiscovered factors associated with treatment discontinuation. This study aimed to evaluate brexpiprazole treatment continuation rate and factors affecting brexpiprazole discontinuation using a database that employs the MENTAT® system with NLP technology. This retrospective observational study evaluated patients with schizophrenia who were newly initiated on brexpiprazole (April 18, 2018-May 15, 2020). The first prescriptions of brexpiprazole were followed up for 180 days. Factors associated with brexpiprazole discontinuation were assessed using structured and unstructured patient data (April 18, 2017-December 31, 2020). The analysis population comprised 515 patients; mean (standard deviation) age of patients was 48.0 (15.3) years, and 47.8 % were male. Using Kaplan-Meier analysis, the cumulative brexpiprazole continuation rate at 180 days was 29 % (estimate: 0.29; 95 % confidence interval, 0.25-0.33). Univariate Cox proportional hazards analysis identified 16 variables independently associated with brexpiprazole discontinuation. Multivariate analysis identified eight variables associated with treatment discontinuation: variables with hazard ratio <1 were the presence of physical complications, longer hospitalization duration, and maximum chlorpromazine-equivalent dose of antipsychotics of >200 to ≤400 mg/day vs ≤200 mg/day in the past year; variables with hazard ratio >1 were previous electroconvulsive therapy, availability of key contact person information, a history of crime committed/reported, increase in brexpiprazole dose to 2 mg in >28 days, and appearance/worsening of symptoms other than positive symptoms. In conclusion, we identified potential new factors that may be associated with brexpiprazole discontinuation, which may improve the treatment strategy and continuation rate in patients with schizophrenia.

Brexpiprazole—Pharmacologic Properties and Use in Schizophrenia and Mood Disorders

In 2002, the first III generation antipsychotic drug was registered—aripiprazole. Its partial dopaminergic agonism underlies its unique mechanism of action and the potentially beneficial influence on the positive, negative, or cognitive symptoms. Due to its relatively high intrinsic activity, the drug could often cause agitation, anxiety, or akathisia. For this reason, efforts were made to develop a drug which would retain the positive favorable actions of aripiprazole but present a more advantageous clinical profile. This turned out to be brexpiprazole, which was registered in 2015. Its pharmacodynamic and pharmacokinetic profile (similarly to the other most recent antipsychotics, i.e., lurasidone or cariprazine) shows promise of increasing the effectiveness of schizophrenia treatment in the dimensions in which the previous antipsychotics were not sufficiently effective, including negative, depressive, or cognitive symptoms. Like other new antipsychotics, it can also be useful in the treatment of mood disorders, for instance drug-resistant depression. Previous reviews focused on the use of brexpiprazole in specific diagnostic groups. The aim of this article is to provide the readers with an overview of data on the mechanism of action, clinical effectiveness in all studied diagnostic groups, as well as potential drug–food interactions, and the safety of brexpiprazole.

Optimal dose of brexpiprazole for augmentation therapy of antidepressant-refractory depression: A systematic review and dose-effect meta-analysis

BACKGROUND

Brexpiprazole augmentation is an effective treatment strategy for antidepressant-refractory depression, but its optimal dosage remains unclear.

AIMS

To find the optimal dosage of brexpiprazole as augmentation of other antidepressants.

METHODS

We searched multiple electronic databases (from inception to September 16th, 2021) to identify double-blind, randomized placebo-controlled fixed-dose trials evaluating brexpiprazole augmentation therapy in adults (≥18 years old, both genders) with major depressive disorder not adequately responding to one or more antidepressant treatment. Our outcomes of interest at 8 weeks (range 4-12 weeks) were efficacy (treatment response defined as 50% or greater reduction in depression severity), tolerability (dropouts due to adverse effects) and acceptability (dropouts for any reason). We performed a random-effects, one-stage dose-effect meta-analysis with restricted cubic splines.

RESULTS

Six studies met the inclusion criteria, including 1671 participants in total. The dose-efficacy curve showed an increase up to doses around 2 mg (odds ratio [OR] 1.52, 95% confidence interval [CI] 1.12-2.06) and then a decreasing trend through the higher licensed dose up to 3 mg (OR 1.40, 95% CI 0.95-2.08). The shape of the dose-tolerability curve was comparable to that of the efficacy and the dose-acceptability curve showed a monotonic increasing trend but both had wide confidence bands.

CONCLUSIONS

One to two milligrams of brexpiprazole as augmentation treatment may achieve an optimal balance between efficacy, tolerability, and acceptability in the acute treatment of antidepressant-refractory depression. However, the small number of included studies limit the reliability of the results. Further research is required to validate the findings.

Perceptual inference, accuracy, and precision in temporal reproduction in schizophrenia

Accumulating evidence suggests that deficits in perceptual inference account for symptoms of schizophrenia. One manifestation of perceptual inference is the central bias, i.e., the tendency to put emphasis on prior experiences over actual events in perceiving incoming sensory stimuli. Using an interval reproduction task, this study aimed to determine whether patients with schizophrenia show a stronger central bias than participants without schizophrenia. In the interval reproduction task, participants were shown a cross on a screen. The cross was replaced with a Gaussian patch for a predetermined time interval, and participants were required to reproduce the interval duration by pressing and releasing the space key. We manipulated the uncertainty of prior information using different interval distributions. We found no difference in the influence of prior information on interval reproduction between patients and controls. However, patients with SZ showed a stronger central bias than healthy participants in the intermediate interval range (approximately 450 ms to 900 ms). It is possible that the patients in SZ have non-uniform deficits associated with interval range or uncertainty of prior information in perceptual inference. Further, the severity of avolition and alogia was correlated with the strength of central bias in SZ. This study provides some insights into the mechanisms underlying the association between schizophrenic symptoms and perceptual inference.

PET as a Translational Tool in Drug Development for Neuroscience Compounds

In central nervous system drug discovery programs, early development of new chemical entities (NCEs) requires a multidisciplinary strategy and a translational approach to obtain proof of distribution, proof of occupancy, and proof of function in specific brain circuits. Positron emission tomography (PET) provides a way to assess in vivo the brain distribution of NCEs and their binding to the target of interest, provided that radiolabeling of the NCE is possible or that a suitable radioligand is available. PET is therefore a key tool for early phases of drug discovery programs. This review will summarize the main applications of PET in early drug development and discuss the usefulness of PET microdosing studies performed with direct labelling of the NCE and PET occupancy studies. The purpose of this review is also to propose an alignment of the nomenclatures used by drug metabolism and pharmacokinetic scientists and PET imaging scientists to indicate key pharmacokinetic parameters and to provide guidance in the performance and interpretation of PET studies.

Molecular Imaging of Dopamine Partial Agonists in Humans: Implications for Clinical Practice

Positron emission tomography (PET) has been used since the late 1980s for the assessment of relationships between occupancy of D_2/3 receptors by antipsychotic drugs in the human brain and the clinical effects and side effects of these compounds in patients. It is now well established for most D_2/3 antagonists, both of the first and the second generation, that the ideal occupancy of their target receptors is between approximately 65 and 80%. If the occupancy is below 65%, the probability of treatment response is reduced, if the occupancy is higher than 80%, the risk for extrapyramidal side-effects increases substantially. However, partial agonist antipsychotics behave different from these rules. It has been shown for all three available drugs of this class (aripiprazole, brexpiprazole, cariprazine) that, due to their special pharmacology, a very high target engagement (>90%) not only is not harmful but represents a prerequisite for antipsychotic efficacy. The available PET studies for these drugs are reviewed in this work. It is demonstrated that optimal plasma levels for partial agonist antipsychotics can be derived from these studies, which can guide individual treatment in routine patient care.

Effect of Novel Antipsychotics on Energy Metabolism - In Vitro Study in Pig Brain Mitochondria

The identification and quantification of mitochondrial effects of novel antipsychotics (brexpiprazole, cariprazine, loxapine, and lurasidone) were studied in vitro in pig brain mitochondria. Selected parameters of mitochondrial metabolism, electron transport chain (ETC) complexes, citrate synthase (CS), malate dehydrogenase (MDH), monoamine oxidase (MAO), mitochondrial respiration, and total ATP and reactive oxygen species (ROS) production were evaluated and associated with possible adverse effects of drugs. All tested antipsychotics decreased the ETC activities (except for complex IV, which increased in activity after brexpiprazole and loxapine addition). Both complex I- and complex II-linked respiration were dose-dependently inhibited, and significant correlations were found between complex I-linked respiration and both complex I activity (positive correlation) and complex IV activity (negative correlation). All drugs significantly decreased mitochondrial ATP production at higher concentrations. Hydrogen peroxide production was significantly increased at 10 µM brexpiprazole and lurasidone and at 100 µM cariprazine and loxapine. All antipsychotics acted as partial inhibitors of MAO-A, brexpiprazole and loxapine partially inhibited MAO-B. Based on our results, novel antipsychotics probably lacked oxygen uncoupling properties. The mitochondrial effects of novel antipsychotics might contribute on their adverse effects, which are mostly related to decreased ATP production and increased ROS production, while MAO-A inhibition might contribute to their antidepressant effect, and brexpiprazole- and loxapine-induced MAO-B inhibition might likely promote neuroplasticity and neuroprotection. The assessment of drug-induced mitochondrial dysfunctions is important in development of new drugs as well as in the understanding of molecular mechanism of adverse or side drug effects.