Impact of smoking behavior on clozapine blood levels - a systematic review and meta-analysis

Letter to the FDA Proposing Major Changes in the US Clozapine Package Insert Supported by Clozapine Experts Worldwide. Part I: A Review of the Pharmacokinetic Literature and Proposed Changes

PURPOSE/BACKGROUND

Clozapine was approved in the United States (US) using 1989 regulations and knowledge. After 30 years, many sections of the US package insert (PI) are outdated.

METHODS

We comprehensively reviewed the literature to propose PI updates. We present the information in 2 articles. In Part I, we focus on basic pharmacology based on 407 relevant articles. Part II focuses on clinical aspects and pharmacovigilance.

FINDINGS/RESULTS

Based on more recent expectations of Food and Drug Administration regulations, we reviewed clozapine basic pharmacology including the following: 1) clearance, 2) pharmacokinetics and pharmacodynamics, and 3) monitoring tools. We identified 9 major problems in the basic pharmacological sections of the PI including the following: 1) in vivo studies indicate that clozapine is dependent on CYP1A2 for its metabolism, 2) the minor role of CYP2D6 in clozapine metabolism requires removing the PI recommendation to lower clozapine doses in CYP2D6 poor metabolizers, 3) in nontoxic concentrations CYP3A4 has a minor role in clozapine metabolism and potent CYP3A4 inhibitors lack clinically relevant effects, 4) several drug-drug interactions need to be updated based on recent literature, 5) systemic inflammation may decrease clozapine metabolism and increase the risk of clozapine intoxication, 6) obesity may decrease clozapine metabolism, 7) patients of Asian and Indigenous American ancestry need lower clozapine doses, 8) personalized titration and c-reactive protein monitoring should be considered until prospective studies are available, and 9) the half-life section needs to be modified to acknowledge that single dosing at night is frequent in the US.

IMPLICATIONS/CONCLUSIONS

An improvement in the US clozapine PI may lead to improvement in PIs worldwide.

Plasma Clozapine in Treatment Refractory Schizophrenia: What Is the Target Range?

BACKGROUND

In treatment-refractory schizophrenia (TRS), a predose plasma concentration of 0.35 mg L-1 is suggested to ensure an adequate trial of clozapine, but the target range may differ between smokers and nonsmokers.

METHOD

We studied data from a clozapine therapeutic drug monitoring service, 1993-2017, with respect to age, sex, smoking status, clozapine dose, estimated clozapine treatment duration, plasma clozapine and norclozapine concentrations, and reason for the request.

RESULTS

There were 35,147 and 88,279 samples from 8882 women and 20,378 men, respectively, for which reasons for the request were specified (26,572 samples, 2 reasons; 6421, 3 or more reasons). More samples were sent for analysis due to suspected adverse drug reactions (ADRs) from women (5.3 vs 4.7%, P < 0.001). The median minimum duration of clozapine treatment before the suspected reaction was 156 days shorter in nonsmokers than smokers of either sex (P < 0.001) and shorter in female than male nonsmokers (189 vs 334 d; P < 0.01). The differences in median plasma clozapine concentrations between suspected ADR (1869/4149 samples from women/men, respectively), and control (10,627/25,848 samples from women/men, respectively) groups were small, averaging 0.03 mg L-1 (P < 0.01), but the median plasma clozapine in the ADR and baseline groups was 0.15 mg L-1 lower in smokers than nonsmokers (P < 0.001).

IMPLICATIONS

The target ranges associated with response to clozapine and minimal ADRs in TRS may be 0.35-0.45 and 0.50-0.60 mg L-1 in smokers and in nonsmokers, respectively. ADRs may occur earlier in treatment in nonsmokers, particularly in women, who in general have higher predose plasma clozapine concentrations than men.

Correlation Between Clozapine and CRP Levels in Relation to Smoking Status

AIMS

Both inflammation and smoking are known to affect clozapine metabolism. However, the impact of inflammation on clozapine metabolism in relation to smoking status is unclear. Therefore, we investigated correlations between C-reactive protein (CRP) and clozapine levels in smokers and non-smokers separately.

METHODS

Patients were included retrospectively from a therapeutic drug monitoring (TDM) service in Oslo, Norway, during January 2005-April 2022. Inclusion criteria were known smoking status and CRP measurements no longer than 7 days before or after clozapine TDM. Exclusion criteria were confirmed blood sampling for TDM outside 10-30 h after the last clozapine intake. Information about clozapine dosing was retrieved from the requisition forms.

RESULTS

In 126 patients fulfilling the criteria (47% smokers), dose-adjusted serum concentration (CD) of clozapine correlated significantly with CRP in non-smokers (R = 0.492; p < 001) but not in smokers (R = 0.191; p = 0.166). When subgrouping non-smoking patients into low CRP (< 5 mg/L; reference [51% of the population]), mid CRP (5-50 [37%]) and high CRP (> 50 [12%]), clozapine CD gradually increased in mid- (+48%, p = 0.004) and high-CRP groups (+204%, p < 0.001) compared with the low-CRP group. No significant differences in clozapine CD were found between CRP groups among smokers (p > 0.15).

CONCLUSIONS

We report a significant correlation between CD of clozapine and CRP levels in non-smoking patients only. In these patients, clozapine CD is more than 3-fold higher at CRP > 50 versus CRP < 5. This suggests that non-smokers are most susceptible to clozapine side effects during inflammation or infection and represent patients where TDM analyses are especially important for guiding clozapine dosing.

Shared medication coordination in a social psychiatric residence: adaptation to meet local requirements

BACKGROUND

Shared medication coordination (MedCo) is vital yet difficult to manage for residents living with severe mental disorders in residential care, where multidisciplinary teams provide support. A successful Shared MedCo model in one residence included three core components: "shared decision-making," "patient involvement" and "MedCo". This model was effective but transfer to other residential settings needed implementation adaptation. The aim of this study was to meet local MedCo requirements by achieving a good fit between a Shared MedCo intervention core components and a social psychiatric residential context.

METHODS

The methodology was guided by a complex intervention adaptation framework involving co-creation with stakeholders to gather iterative feedback. The intervention was adapted through a systematic four-phase process and tested through shared consultations. Ten residents took part in the test, and the intervention's feasibility and acceptability were assessed.

FINDINGS

The adaptation process ensured a good fit between the intervention's core components and the new context. Stakeholder input provided crucial content and contextual insights, while planned adaptations laid the foundation for modulating the individual residence Shared MedCo model. Iterative adaptations during the test phase refined the intervention, leading to near-routine performance by the tenth consultation. Residents gained a stronger voice in their healthcare, and all ten had their medication coordinated and optimised. The intervention was found feasible and acceptable.

CONCLUSION

For effective implementation, complex multidisciplinary Shared MedCo interventions require contextual adaptation and active stakeholder involvement. The shared MedCo intervention offers a guideline for achieving a good fit between the intervention core components and diverse residential contexts, ensuring successful medication coordination for residents living with severe mental disorders.

Comparison of Effectiveness and Tolerability of Clonidine and Trihexyphenidyl in Clozapine-Induced Hypersalivation

PURPOSE/BACKGROUND

Clozapine-induced hypersalivation is one of the most common bothersome adverse reactions of clozapine. The management strategies for this condition remain inadequately studied and understood. The objective of the study is to compare the effectiveness and tolerability of (1) trihexyphenidyl 5 mg/d, (2) clonidine 0.15 mg/d, or (3) a reduction of clozapine dosage by 25 to 50 mg/d for managing clozapine-induced hypersalivation.

METHODS/PROCEDURES

A randomized, open-label, non-placebo-controlled clinical trial was conducted from December 2023 to May 2024. Eligible patients were randomly assigned to 1 of 3 groups. Primary outcomes were assessed using the Drooling Severity and Frequency Scale (DSFS) and the Nocturnal Hypersalivation Rating Scale (NHRS) at baseline, week 4, and week 8. Quality of life assessed using the pharmaceutical therapy for quality of life short version and adverse drug reactions were recorded as secondary outcomes.

FINDINGS/RESULTS

A total of 67 patients were randomly assigned to 1 of 3 treatment groups. By week 8, significant reductions in DSFS and NHRS scores were observed in all groups, with clonidine showing the greatest improvement. Trihexyphenidyl was also effective, whereas reducing clozapine dose resulted in more modest improvements. Quality of life improved significantly across all groups, with the greatest improvement observed in the clonidine group. The most common adverse effects were dry mouth, constipation, drowsiness, and dizziness.

IMPLICATIONS/CONCLUSIONS

Clonidine and trihexyphenidyl appear to be more effective options for managing clozapine-induced hypersalivation compared to clozapine dose reduction.

Vaccination and clozapine use: a systematic review and an analysis of the VAERS database

In the context of COVID-19 concerns related to the potential interactions between clozapine and vaccination arose. With the ultimate goal of deriving recommendations for clinical practice, we systematically reviewed the current evidence regarding altered vaccine effectiveness in clozapine-treated patients and safety aspects of vaccination, such as haematological changes and the impact of vaccines on clozapine blood levels, in clozapine-treated patients. A systematic PRISMA-conform literature search of four databases (PubMed, PsycINFO, EMBASE and Cochrane Library) complemented by a case-by-case analysis of the Vaccine Adverse Event Reporting System (VAERS) database was performed. We then systematically appraised the joint evidence and tried to derive recommendations for clinical practice. 14 records were included in this analysis. These records consisted of 5 original articles and 9 case reports. Among the original articles, two studies provided data on the association between clozapine use and antibody responses to vaccination, both indicating that clozapine use in schizophrenia may be associated with reduced levels of immunoglobulins. Additionally, three studies examined vaccine safety in clozapine-treated patients, with no clinically significant adverse effects directly attributable to the interplay between vaccinations and clozapine. VAERS Analysis encompassed 137 reports and showed no consistent evidence of an increased risk for clozapine blood level increases or adverse events. We found no evidence indicating that clozapine impairs the effectiveness of vaccines. Moreover, no serious safety concerns seem to apply when patients on clozapine are receiving vaccines. However, it is crucial to acknowledge that data on the interaction between clozapine and vaccines remain limited.

The effects of clinical and pharmacological factors on the ratio of clozapine to norclozapine in psychiatric patients

Background

Due to its exceptional effectiveness, clozapine (CLO), whose metabolite is norclozapine (NCLO), is a drug of choice in the management of treatment-resistant schizophrenia. The purpose of this study was to assess the factors modifying the CLO/NCLO ratio (CNR).

Methods

A total of 446 blood samples (233 of which were drawn from females and 213 from males, aged from 18 to 77 years) were analyzed in this study. The patients were treated at a psychiatric hospital in the period 2016-2021. Serum CLO and NCLO levels were determined with high-performance liquid chromatography coupled with a UV detector.

Results

The median CNR was 2.38 (minimum 0.30, maximum 14.36). Our analysis showed that neither sex (p= 0.135) nor smoking (p = 0.774) had any significant effect on the CNR. However, increased doses of CLO resulted in lower CNR values (p = 0.005). Concomitant use of other psychotropic drugs increased the CNR (p = 0.001).

Discussion

The results of our study indicate a need for personalized CLO treatment. Assessing the CNR may be useful in identifying CLO interaction with other psychotropic drugs.

Optimization of Clozapine Treatment: Study of Variables Affecting Response in Uruguayan Patients With Schizophrenia

PURPOSE/BACKGROUND

Clozapine is the recommended drug for treatment-resistant schizophrenia. Drug response could be affected by numerous factors such as age, sex, body mass index, co-medication, consumption of xanthine-containing beverages, smoking, and genetic variants of the enzymes involved in clozapine metabolism (CYP1A2, CYP3A4, and, to a lesser extent, CYP2C19 and CYP2D6). This study evaluated genetic and nongenetic variables that may affect clozapine plasma concentrations in Uruguayan patients with schizophrenia.

METHODS/PROCEDURES

Demographic data including sex, age, ethnicity, body weight, smoking habit, concomitant medication, and xanthine consumption were collected through a data collection form. Clozapine and norclozapine concentrations were determined using an HPLC system equipped with a UV detector. Genetic variants were determined through next-generation sequencing using Illumina sequencing technology and a panel of DNA probes.

FINDINGS/RESULTS

Fifty patients were included in the study. After evaluation, only tobacco use and obesity had a significant impact on clozapine exposure (P < 0.05). The high prevalence of the genetic variant CYP1A2*1F may account for the significant impact that tobacco smoking has on clozapine concentrations. Some common adverse effects observed in this study depend on clozapine plasma concentrations, such as constipation and sialorrhea.

IMPLICATIONS/CONCLUSIONS

These types of studies provide the clinician with tools to optimize clozapine therapy, attempting to use the minimum effective dose and attenuating the burden of concentration-dependent adverse reactions.

Lessons learnt in the end-of-life management of a hospice inpatient with advanced oropharyngeal cancer established on clozapine for treatment-resistant schizophrenia

Clozapine is a tightly controlled medication used effectively as a last-line agent in treatment-resistant schizophrenia, with a relatively narrow therapeutic window and significant interactions. Both underdosing and toxicity can be catastrophic to the patient. Patients with complex mental health illnesses are more at risk of head and neck cancers due to the high prevalence of associated risk factors including smoking, diet and alcohol. These patients also face barriers to accessing and using healthcare and may not tolerate procedures for artificial routes for feeding and medications. As the disease progresses, these patients are vulnerable to clozapine toxicity from factors such as constipation, reduction in cigarette smoking, weight loss and medication interactions. Conversely, they also risk underdosing with a relapse of distressing psychotic symptoms as the swallow deteriorates. This case highlights the need for considerate planning, prescribing, close monitoring and awareness alongside the importance of multidisciplinary working when caring for this patient group.

Plasma Clozapine and N -Desmethylclozapine (Norclozapine) Concentrations and the Clozapine/Norclozapine Ratio : Effect of Dose, Sex, and Cigarette Smoking

BACKGROUND

Smoking enhances plasma clozapine clearance, but the magnitude of the effect across the dose and age ranges is unclear.

METHODS

We audited clozapine dose and predose plasma clozapine and N -desmethylclozapine (norclozapine) concentrations by sex and smoking habit in samples submitted for clozapine TDM, 1996-2017.

RESULTS

There were 105,316/60,792 and 34,288/31,309 samples from male/female smokers/nonsmokers, respectively. There were distinct dose-median plasma concentration trajectories for male/female smokers/nonsmokers across the range <50 to >850 mg d -1 . For both sexes, the percentage difference in median plasma clozapine in nonsmokers versus smokers averaged 50% but was greatest for men (76%) and women (59%) in the 151 to 250 mg d -1 dose band. In men, the percentage difference declined steadily to 34% at doses of ≥850 mg d -1 . In women, the difference after falling initially remained relatively constant at 40% to 54%. The pattern in median plasma clozapine/norclozapine ratio by plasma clozapine concentration and dose groups was independent of sex and smoking habit, but increased with plasma clozapine concentration (higher ratio at higher concentrations) and also changed with dose. Median plasma clozapine concentration and median clozapine dose by sex and smoking habit were similar up to age 60 years. Proportional weight gain was similar over time in smokers and nonsmokers of either sex.

IMPLICATIONS

These data explain the variations in the effect size of starting or stopping smoking on plasma clozapine concentration at constant dose reported in different studies. Changes in smoking habit in patients prescribed clozapine require prompt dose adjustment.

Increased antipsychotic drug concentration in hospitalized patients with mental disorders following COVID-19 infection: a call for attention

Purpose

Examine the alterations in antipsychotic concentrations following coronavirus disease-2019 (COVID-19) infection among hospitalized patients with mental disorders and conduct an analysis of the factors influencing these changes.

Methods

Data were collected from inpatients at Beijing Huilongguan Hospital between December 12, 2022, and January 11, 2023, pre- and post-COVID-19. Based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, 329 inpatients with mental disorders were included (3 with incomplete data excluded). Primary outcomes assessed changes in antipsychotic concentrations pre- and post-COVID-19, while secondary outcomes examined factors linked to concentration increases and antipsychotic dose adjustments.

Results

Clozapine (P < 0.001), aripiprazole (P < 0.001), quetiapine (P = 0.005), olanzapine (P < 0.001), risperidone (P < 0.001), and paliperidone (P < 0.001) concentrations increased post-COVID-19 in patients with mental disorders. Notably, clozapine concentration surpassing pre-infection levels was highest. Clozapine users were more likely to adjust their dose (50.4%) compared to olanzapine (17.5%) and other antipsychotics. Moreover, traditional Chinese patent medicines and antibiotics during COVID-19 infection were associated with antipsychotic reduction or withdrawal (OR = 2.06, P = 0.0247; OR = 7.53, P = 0.0024, respectively).

Conclusion

Antipsychotic concentrations in hospitalized patients with mental disorders increased after COVID-19 infection, that may be related not only to COVID-19, but also to the use of Chinese patent medicines during infection. The pre-infection concentration and types of antipsychotics, patient's gender, and combination of traditional Chinese medicine or antibiotics, were factors found to correlate with increased drug concentrations and necessitate dose adjustments.

Overcoming the barriers to identifying and managing treatment-resistant schizophrenia and to improving access to clozapine: A narrative review and recommendation for clinical practice

Clozapine is the only approved antipsychotic for treatment-resistant schizophrenia (TRS). Although a large body of evidence supports its efficacy and favorable risk-benefit ratio in individuals who have failed two or more antipsychotics, clozapine remains underused. However, variations in clozapine utilization across geographic and clinical settings suggest that it could be possible to improve its use. In this narrative review and expert opinion, we summarized information available in the literature on the mechanisms of action, effectiveness, and potential adverse events of clozapine. We identified barriers leading to discouragement in clozapine prescription internationally, and we proposed practical solutions to overcome each barrier. One of the main obstacles identified to the use of clozapine is the lack of appropriate training for physicians: we highlighted the need to develop specific professional programs to train clinicians, both practicing and in residency, on the relevance and efficacy of clozapine in TRS treatment, initiation, maintenance, and management of potential adverse events. This approach would facilitate physicians to identify eligible patients and offer clozapine as a treatment option in the early stage of the disease. We also noted that increasing awareness of the benefits of clozapine among healthcare professionals, people with TRS, and their caregivers can help promote the use of clozapine. Educational material, such as leaflets or videos, could be developed and distributed to achieve this goal. The information provided in this article may be useful to improve disease burden and support healthcare professionals, patients, and caregivers navigating the complex pathways to TRS management.

Risk Phenotypes, Comorbidities, Pharmacotherapy, and Electroconvulsive Therapy (ECT) in a Cohort with Difficult-to-Treat Depression in Comparison to an Unmedicated Control Group

BACKGROUND

Approximately 15-25% of depressed patients suffer from difficult-to-treat depression (DTD). Patients with DTD require a thorough examination to avoid the oversight of treatable (psychiatric/somatic) comorbidities or (pseudo-)resistance to antidepressant drugs (ADs). Polymorphisms of the cytochrome P450 (CYP) enzymes 2D6 and 2C19, which play a major role in the metabolism of ADs, may contribute to resistance to ADs. Patients with DTD might benefit from electroconvulsive therapy (ECT).

METHODS

We enrolled 109 patients with DTD and 29 untreated depressed controls (UDC). We assessed risk phenotypes, comorbidities, and treatment, including ECT. We also performed pharmacokinetic analyses of CYP2D6 and CYP2C19.

RESULTS

DTD patients significantly more often suffered from comorbid psychiatric diseases, especially ICD-10: F40-F48 (DTD:40.4%, UDC:17.2%, OR 11.87, p=0.011) than UDC patients. DTD patients receiving ECT were more likely to achieve remission (37.7% vs. 11.8%, OR=3.96, p=0.023). Treatment with ADs did not differ between remitters and non-remitters. No significant differences were observed in the distribution of CYP2D6 and CYP2C19 variants between both groups.

CONCLUSION

Patients with DTD appear to experience comorbid neurotic stress and somatoform disorders (ICD-10: F40 - F48) more frequently. Therefore, a comprehensive differential diagnosis is crucial when patients do not respond sufficiently to antidepressant medication. Genotyping CYP2D6 and CYP2C19 should be considered.

A systematic review of clozapine for aggression and violence in patients with schizophrenia or schizoaffective disorder

Although uncommon, the risk of aggression and violence is greater in people with schizophrenia than in the general population. Clozapine is the "gold standard" pharmacologic treatment for the management of persistent agitation and aggression in people with schizophrenia and is consistently recommended by guidelines and reviews for this purpose. Although clozapine is indicated for treatment-resistant schizophrenia based on its superior efficacy, studies have proposed that clozapine may have specific properties that ameliorate aggression and hostility that are distinct from its antipsychotic effects. A literature review was conducted on June 3, 2023, using the US National Library of Medicine's PubMed resource to identify articles focusing on clozapine for the treatment of aggression, violence, and/or hostility in patients with schizophrenia or schizoaffective disorder. The majority of evidence, including from randomized control trials, supports the utilization of clozapine as maintenance treatment for persistent aggressive behavior in patients with schizophrenia, and supports that its anti-aggressive effects may be independent from its antipsychotic properties (e.g. - treatment of hallucinations and delusions). Future randomized control studies evaluating clozapine and clozapine serum levels with aggression as the primary outcome would be of benefit.

Rapid Metabolism Underlying Subtherapeutic Serum Levels of Atypical Antipsychotics Preceding Clozapine Treatment: A Retrospective Analysis of Real-World Data

INTRODUCTION

Adequate antipsychotic treatment intensity is required before diagnosing resistant schizophrenia and initiating clozapine treatment. We aimed to investigate potential rapid drug metabolism underlying low dose-adjusted serum concentration (CD) of non-clozapine atypical antipsychotics preceding clozapine treatment.

METHODS

Patients using non-clozapine, atypical antipsychotics (aripiprazole, risperidone, olanzapine, or quetiapine) within 1 year before starting clozapine were included in this study from a therapeutic drug monitoring service in Oslo, Norway, between 2005 and 2023. Patients were assigned into low CD (LCD) and normal CD (NCD) subgroups. Using a reference sample with 147,964 antipsychotic measurements, LCD was defined as CDs below the 25th percentile, while patients with NCD exhibited CDs between the 25th and 75th percentile of the respective reference measurements. Metabolic ratios, doses, and frequency of subtherapeutic levels of non-clozapine antipsychotics were compared between LCD and NCD groups.

RESULTS

Preceding clozapine treatment, 110 out of 272 included patients (40.4%) were identified with LCD. Compared with the NCD group, LCD patients exhibited higher metabolic ratios of olanzapine (1.5-fold; p < 0.001), quetiapine (3.0-fold; p < 0.001), and risperidone (6.0-fold; p < 0.001). Metabolic ratio differences were independent of smoking and CYP2D6 genotype for olanzapine (p = 0.008) and risperidone (p = 0.016), respectively. Despite higher doses of olanzapine (1.25-fold; p = 0.054) and quetiapine (1.6-fold; p = 0.001) in LCD versus NCD patients, faster metabolism among the former was accompanied by higher frequencies of subtherapeutic levels of olanzapine (3.3-fold; p = 0.044) and quetiapine (1.8-fold; p = 0.005).

CONCLUSION

LCD and associated rapid metabolism of non-clozapine antipsychotics is frequent before starting clozapine treatment. For olanzapine and quetiapine, this is associated with significantly increased risk of having subtherapeutic concentrations.

Once-daily versus divided dosing regimens of clozapine: A cross-sectional study in Singapore

INTRODUCTION

Clozapine is recognized as the gold standard medication for treatment-resistant schizophrenia. Despite the general recommendation of administering in a divided dosing regimen, clozapine is often prescribed once daily at night in clinical practice. This study aims to compare patient characteristics, psychiatric symptoms, side effects, and plasma concentration of clozapine between once-daily dosing and divided dosing regimens.

METHODS

This cross-sectional study included 159 participants with treatment-resistant schizophrenia or schizoaffective disorder. Participant's demographic information, anthropometric data, and medical history were collected. Their psychiatric symptoms, cognition, functioning, and side effects were evaluated.

RESULTS

Once-daily dosing regimen was associated with younger age and competitive employment. Lower clinical symptom severity, better functioning and cognitive performance were observed in the once-daily dosing group. Lower daily dose of clozapine, trough plasma concentrations of clozapine and norclozapine were also significantly associated with once-daily dosing regimen.

CONCLUSION

The study results support once-daily dosing of clozapine as a viable option to selected patients in clinical practice, as no association of severe symptoms or side effects were associated with once-daily dosing regimen. More studies are needed to examine the relationship between clinical outcomes and clozapine dosing regimen.

[Management of treatment resistance-Treatment-resistant schizophrenia]

Despite a very high prevalence and substantial impairments among affected individuals, treatment-resistant schizophrenia (TRS) has not been sufficiently researched in clinical research in the field of psychiatric disorders and the pathophysiology is still poorly understood. A better clinical and pathophysiological understanding of this heterogeneous and severely affected population of people with persistent symptoms in different domains is necessary in order not only to be able to intervene early but also to develop novel therapeutic strategies or individualized treatment approaches. This review article presents the state of the art criteria of the pharmacological TRS, neurobiological disease models and predictive factors for TRS as well as the phenomenon of pseudo-treatment resistance and the clinical management of TRS. In the future, not only the use of operationalized criteria and definitions of TRS in longitudinal studies and randomized-controlled trials (RCTs) are paramount, but also the observation of trajectories with the integration of multimodal longitudinal phenotyping and the longitudinal collection of clinical routine data in academic research, which will be possible in the newly created German Center for Mental Health (DZPG).

Sex differences in effectiveness and adverse effects of mood stabilizers and antipsychotics: A systematic review

BACKGROUND

Psychiatric disorders differ in their prevalence, symptom profiles, and disease courses in men and women. However, sex differences in psychiatric disorders have not received enough attention to guide treatment recommendations. This systematic review aims to summarize sex differences in the treatment responses and adverse effects of mood stabilizers and antipsychotics transdiagnostically.

METHODS

We conducted a systematic review following the PRISMA 2020 statement (CRD42020212478). A literature search was conducted using MEDLINE, Embase, Cochrane Central, PsycINFO, Web of Science Core Collection, and Scopus databases. Studies comparing mood stabilizer or antipsychotic treatment outcomes in men and women were included. JBI critical appraisal checklists were used to assess bias risk.

RESULTS

Out of 4866 records, 129 reports (14 on mood stabilizers, 115 on antipsychotics) with varying designs were included. Sample sizes ranged from 17 to 22,774 participants (median = 147). The most common psychiatric diagnoses were schizophrenia spectrum (n = 109, 84.5 %) and bipolar disorders (n = 38, 29.5 %). Only four studies explored sex differences in mood stabilizer treatment response. In 40 articles on antipsychotic treatment response, 18 indicated no sex difference, while 16 showed females had better outcomes. Women had more adverse effects with both mood stabilizers and antipsychotics. The risk of bias was low in 84 (65.1 %) of studies.

LIMITATIONS

Substantial heterogeneity among the studies precluded performing a meta-analysis.

CONCLUSION

Number of studies focusing on sex differences in treatment outcomes of mood stabilizers is limited. Women may respond better to antipsychotics than men, but also experience more side effects. The impact of pharmacokinetics on sex differences warrants more attention.

Relationship between stable smoking behavior and cognitive function in male schizophrenia patients

OBJECTIVE

To explore the relationship between stable smoking behavior and cognitive function in male schizophrenia patients.

METHODS

A simple random sampling method is applied to select 120 patients with schizophrenia admitted to a hospital from August 2020 to December 2022 as the subjects. They are divided into two groups based on whether they smoked or not. Their cognitive function is evaluated using the Stroop test (SWCT), continuous task test (CPT), and Chinese version of the Schizophrenic Cognitive Function Battery Test (MCCB). The Spearman correlation analysis is applied to verify the correlation between smoking behavior and SWCT, CPT, and MCCB in patients. Additionally, the Fagerstrom Nicotine Dependence Scale (FTND) is used to evaluate the nicotine dependence degree in smoking group patients. Pearson correlation analysis verifies the correlation between nicotine dependence and SWCT, CPT, MCCB in smoking group patients.

RESULTS

Among 120 patients include in this study, 3 have symptoms during the trial period, and 1 patient has an error in filling out the questionnaire, all of which are excluded. Finally, 116 valid documents are collected, with an effective recovery rate of 96.67%. According to the SWCT test results, the number of single word errors, single word time, double word errors, and double word time in the smoking group exceed the non-smoking group (P < 0.05). According to the CPT test results, the number of correct reactions in the smoking group is below the non-smoking group. The correct average reaction time, error rate of interference items, and error rate of ineffective items exceed the non-smoking group (P < 0.05). According to the MCCB test results, the scores of connectivity, visual spatial memory, and continuous operation test in the smoking group are below the non-smoking group (P < 0.05). The Spearman correlation analysis results show that stable smoking behavior in male schizophrenia patients is positively correlated with the number of single word errors, double word errors, double word time, correct mean reaction time, interference item error rate, and invalid item error rate (r = 0.216-0.524, P < 0.05). It is also positively correlated with the number of correct reactions, immediate memory, language function, delayed memory, MCCB connectivity, visual spatial memory, and continuous operation (r = -0.212-0.356, P < 0.05). The Pearson correlation analysis results show that the nicotine dependence degree in stable male schizophrenia patients is negatively correlated with monochromatic error count, immediate memory, visual span, attention, and MCCB scores (r = -0.321-0.930, P < 0.05).

CONCLUSION

Smoking in male schizophrenic patients may have impacts on their cognitive function. This impact worsens as the patient's nicotine dependence increases, especially on their memory function. Effective measures should be taken in clinical practice to correct patients' smoking behavior, reduce their nicotine dependence, and improve their cognitive function.

Tobacco smoking and nicotine vaping in persons with first episode psychosis

Tobacco smoking is highly prevalent in persons with psychosis and is the leading cause of preventable mortality in this population. Less is known about tobacco smoking in persons with first episode psychosis (FEP) and there have been no estimates about the prevalence of nicotine vaping in FEP. This study reports rates of tobacco smoking and nicotine vaping in young people with FEP enrolled in Coordinated Specialty Care programs in Pennsylvania and Maryland. Using data collected from 2021 to 2023, we examined lifetime and recent smoking and vaping and compared smokers and vapers to nonusers on symptoms, functioning, and substance use. The sample included 445 participants aged 13-35 with recent psychosis onset. Assessments were collected by program staff. Overall, 28 % of participants engaged in either smoking or vaping within 30 days of the admission assessment. Smokers and vapers were disproportionately male, cannabis users, and had lower negative symptom severity than non-smokers. Vapers had higher role and social functioning. Both smoking and vaping were related to a longer time from psychosis onset to program enrollment. We compare these findings to previous studies and suggest steps for addressing smoking and vaping in this vulnerable population.

Clinical and pharmacological factors influencing serum clozapine and norclozapine levels

Background

Clozapine (CLO) is a very effective antipsychotic, whose use is associated with dose-dependent risk of complications. Due to high interindividual variability in CLO metabolism, there is a need to identify factors affecting the blood concentrations of CLO and its active metabolite, norclozapine (NCLO).

Methods

A total of 446 blood samples (collected from 233 women and 213 men, aged from 18 to 77 years) were included in this study and analyzed for CLO and NCLO concentrations. The patients were treated at a psychiatric hospital in Warsaw in the years 2016-2021. Serum CLO and NCLO concentrations were determined with high-performance liquid chromatography coupled to UV.

Results

The following factors were shown to increase serum CLO and NCLO levels: higher CLO dose (p < 0.001), female sex (p < 0.001), nonsmoker status (p < 0.001), the use of more than two additional psychotropic drugs (only in the case of CLO; p = 0.046), concomitant use of beta-blockers (for CLO p = 0.049; for NCLO p < 0.001), and older age (for CLO p < 0.001; for NCLO p = 0.011). Despite the use of CLO at daily doses within the recommended range (200-450 mg), the evaluated serum CLO and NCLO levels were within the therapeutic ranges in only 37% and 75% of cases, respectively, with 5.6% of cases exceeding the CLO toxicity threshold.

Discussion

The use of CLO at recommended doses does not guarantee achieving therapeutic concentrations of CLO or NCLO. Women and nonsmokers were at the highest risk of having toxic CLO levels.

Exploring the Smoking-Epilepsy Nexus: a systematic review and meta-analysis of observational studies : Smoking and epilepsy

BACKGROUND

Epilepsy, characterized by recurrent unprovoked seizures, poses significant challenges to affected individuals globally. While several established risk factors for epilepsy exist, the association with cigarette smoking remains debated. This study aims to conduct systematic review and meta-analysis to elucidate the potential association between smoking and the likelihood of epilepsy.

METHODS

The search was performed on March 31st, 2023, using the Medline, Embase, Web of Science, Scopus, and ScienceDirect. We included cohort, cross-sectional, and case-control studies in our meta-analysis, conducting subgroup analyses based on smoking history, sex, and epilepsy type to yield specific insights.

RESULTS

We identified 2550 studies, of which 17 studies were finally included in this study. The pooled odds ratio of epilepsy was 1.14 (0.96-1.36) in smokers compared to non-smokers. In current smokers compared to non-smokers, the odds ratio was 1.46 (1.13-1.89), while, in former smokers compared to non-smokers, the odds ratio was 1.14 (0.83-1.56).

CONCLUSIONS

While the overall association between smoking and epilepsy did not reach statistical significance, a notable association was found among current smokers. The study emphasizes the importance of smoking cessation as a potential preventive measure against epilepsy, especially given the proconvulsive effects of nicotine. Future research should address limitations and explore specific clinical scenarios to enhance our understanding of the complex relationship between cigarette use and epilepsy.

SYSTEMATIC REVIEW REGISTRATION

CRD42022342510.

Evaluating Monitoring Guidelines of Clozapine-Induced Adverse Effects: a Systematic Review

BACKGROUND AND OBJECTIVES

Despite the evidence that no other antipsychotic is effective as clozapine for the treatment of resistant schizophrenia, it is associated with various metabolic, neuroendocrine, cardiovascular, and gastrointestinal adverse effects. Guidelines aiming to address the monitoring of clozapine's (serious) adverse effects can be helpful to prevent and treat these effects. However, many of these guidelines seem to lack one or more important monitoring recommendations. We aimed to systematically review the content and quality of existing monitoring guidelines/recommendations for clozapine-induced adverse effects.

METHODS

A comprehensive and systematic literature search, using the MEDLINE, Embase, Web of Science, and Cochrane databases, was conducted for guidelines/recommendations on the monitoring of clozapine-induced adverse events, published between January 2004 and April 2023 (last search 16 April 2023). Only peer-reviewed published guidelines reporting on the comprehensive monitoring of all major clozapine-induced adverse effects and including evidence-based recommendations, developed after the year 2004, were included. Studies reporting on the monitoring of adverse effects of clozapine without being a formal guideline, guidelines reporting on the monitoring of one or a limited number of adverse effects of clozapine, guidelines that were not peer reviewed or published, expert opinion papers without formal consensus guideline development, or guidelines developed before the year 2004, were excluded. The Appraisal of Guidelines for Research and Evaluation II (AGREE-II) tool was used to evaluate the guidelines/recommendations' quality.

RESULTS

Only one guideline met the inclusion criteria. This consensus statement made recommendations for hematological monitoring, and the monitoring of metabolic, cardiac, and three other adverse effects. Highest scores for the qualitative assessment were found for the domains "scope and purpose" (66.7%), "clarity of presentation" (44.4%), and "editorial independence" (66.7%). Lowest scores were found for "rigor of development" (14.6%) and "applicability" (0%).

CONCLUSIONS

Future guidelines should develop more comprehensive recommendations about specific clozapine-induced adverse effects, including constipation, myocarditis, tachycardia, and seizures, as well as include a rechallenge policy. There is an urgent need for well-developed, methodologically stringent, guidelines.

REGISTRATION

PROSPERO registration number, CRD42023402480.

Polygenetic risk scores and phenotypic constellations of obsessive-compulsive disorder in clozapine-treated schizophrenia

Obsessive-compulsive symptoms (OCS) are frequently observed in individuals with schizophrenia (SCZ) treated with clozapine (CLZ). This study aimed to analyze prevalence of OCS and obsessive-compulsive disorder (OCD) in this subgroup and find possible correlations with different phenotypes. Additionally, this is the first study to examine polygenetic risk scores (PRS) in individuals with SCZ and OCS. A multicenter cohort of 91 individuals with SCZ who were treated with CLZ was recruited and clinically and genetically assessed. Symptom severity was examined using the Positive and Negative Symptom Scale (PANSS), Clinical Global Impression Scale (CGI), the Calgary Depression Scale for Schizophrenia (CDSS), Global Assessment of Functioning Scale (GAF) and Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). Participants were divided into subgroups based on phenotypic OCS or OCD using Y-BOCS scores. Genomic-wide data were generated, and PRS analyses were performed to evaluate the association between either phenotypic OCD or OCS severity and genotype-predicted predisposition for OCD, SCZ, cross-disorder, and CLZ/norclozapine (NorCLZ) ratio, CLZ metabolism and NorCLZ metabolism. OCS and OCD were frequent comorbidities in our sample of CLZ-treated SCZ individuals, with a prevalence of 39.6% and 27.5%, respectively. Furthermore, the Y-BOCS total score correlated positively with the duration of CLZ treatment in years (r = 0.28; p = 0.008) and the PANSS general psychopathology subscale score (r = 0.23; p = 0.028). A significant correlation was found between OCD occurrence and PRS for CLZ metabolism. We found no correlation between OCS severity and PRS for CLZ metabolism. We found no correlation for either OCD or OCS and PRS for OCD, cross-disorder, SCZ, CLZ/NorCLZ ratio or NorCLZ metabolism. Our study was able to replicate previous findings on clinical characteristics of CLZ-treated SCZ individuals. OCS is a frequent comorbidity in this cohort and is correlated with CLZ treatment duration in years and PANSS general psychopathology subscale score. We found a correlation between OCD and PRS for CLZ metabolism, which should be interpreted as incidental for now. Future research is necessary to replicate significant findings and to assess possible genetic predisposition of CLZ-treated individuals with SCZ to OCS/OCD. Limitations attributed to the small sample size or the inclusion of subjects on co-medication must be considered. If the association between OCD and PRS for CLZ metabolism can be replicated, it should be further evaluated if CYP1A2 alteration, respectively lower CLZ plasma level, is relevant for OCD development.

A population pharmacokinetic model to guide clozapine dose selection, based on age, sex, ethnicity, body weight and smoking status

AIMS

Guidance on clozapine dosing in treatment-resistant schizophrenia is based largely on data from White young adult males. This study aimed to investigate the pharmacokinetic profiles of clozapine and N-desmethylclozapine (norclozapine) across the age range, accounting for sex, ethnicity, smoking status and body weight.

METHODS

A population pharmacokinetic model, implemented in Monolix, that linked plasma clozapine and norclozapine via a metabolic rate constant, was used to analyse data from a clozapine therapeutic drug monitoring service, 1993-2017.

RESULTS

There were 17 787 measurements from 5960 patients (4315 male) aged 18-86 years. The estimated clozapine plasma clearance was reduced from 20.2 to 12.0 L h-1 between 20 and 80 years. Model-based dose predictions to attain a predose plasma clozapine concentration of 0.35 mg L-1 was 275 (90% prediction interval 125, 625) mg day-1 in nonsmoking, White males weighing 70 kg and aged 40 years. The corresponding predicted dose was increased by 30% in smokers, decreased by 18% in females, and was 10% higher and 14% lower in otherwise analogous Afro-Caribbean and Asian patients, respectively. Overall, the predicted dose decreased by 56% between 20 and 80 years.

CONCLUSION

The large sample size and wide age range of the patients studied allowed precise estimation of dose requirements to attain predose clozapine concentration of 0.35 mg L-1 . The analysis was, however, limited by the absence of data on clinical outcome and future studies are required to determine optimal predose concentrations specifically in those aged over 65 years.

Differences in olfactory dysfunction and its relationship with cognitive function in schizophrenia patients with and without auditory verbal hallucinations

Olfactory discrimination dysfunction has been observed in patients with schizophrenia (SCZ), but its relationship with cognitive function has not been clarified. The purpose of this study was to examine the differences in olfactory identification function in SCZ patients with and without auditory verbal hallucinations (AVHs) and its relationship with cognitive function. Olfactory identification function was measured in 80 SCZ patients with AVHs, 57 SCZ patients without AVHs, and 87 healthy controls (HC). Clinical symptom scores and neuropsychological measures were also administered to all corresponding subjects. Compared to HC, SCZ patients showed significant deficits in olfactory identification and cognitive function, but there were no differences in olfactory identification dysfunction and cognitive dysfunction between the two subgroups. In the non-AVHs subgroup only, poorer Olfactory Stick Identification Test for Japanese (OSIT-J) scores were significantly and positively correlated with total and delayed recall (Bonferroni correction, p < 0.002). Stepwise regression analysis revealed that factors affecting olfactory identification impairment differed in the two SCZ patient subgroups. In conclusion, this study highlights the commonality of olfactory identification dysfunction in SCZ patients and the importance of olfactory assessment of different subtypes of SCZ patients.

Effect of Cigarette Smoking on Clozapine Dose and on Plasma Clozapine and N-Desmethylclozapine (Norclozapine) Concentrations in Clinical Practice

BACKGROUND

Cigarette smoking enhances plasma clozapine clearance and thus affects the clozapine dose requirement.

METHODS

We compared clozapine daily dose and plasma clozapine and N-desmethylclozapine (norclozapine) concentrations in male and female smokers and nonsmokers in samples submitted for clozapine therapeutic drug monitoring (1996-2017).

RESULTS

There were 105,316/60,792 and 34,290/31,309 samples with dose information from male and female smokers/nonsmokers, respectively. There was information on the number of cigarettes smoked daily for 12,842 samples (8409 patients) and 3948 samples (2753 patients) from men and women, respectively. Of these, 574 and 253 samples were from men and women, respectively, who reported smoking 1-9 cigarettes daily.In both sexes, the median clozapine doses in the nonsmokers were 75%-80% of those in the smokers, but the median plasma clozapine and norclozapine concentrations were 136% higher. The effect of smoking on the dose and on median plasma clozapine and norclozapine concentrations seemed maximal after 2-3, perhaps fewer, cigarettes daily in males. In females, the effect of smoking seemed to be near maximal after some 4-5 cigarettes per day.

IMPLICATIONS

The optimum target range for predose plasma clozapine may be different in smokers (0.35-0.45 mg L-1) as opposed to nonsmokers (0.50-0.60 mg L-1). That changes in clozapine clearance are likely near maximal with cigarette smoking as low as 2-3 d-1 in males, perhaps slightly more in females, emphasizes that covert or passive smoking may be an important factor in seemingly random changes in plasma clozapine concentration at constant dose.

Effect of smoking habits and concomitant valproic acid use on relapse in patients with treatment-resistant schizophrenia receiving clozapine: A 1-year retrospective cohort study

INTRODUCTION

No study has investigated the impact of smoking habits and concomitant valproic acid (VPA) use on clinical outcomes in maintenance treatment with clozapine. Thus, we aimed to examine the effect of smoking habits and concomitant VPA use on relapse during the first year after discharge in patients with treatment-resistant schizophrenia (TRS) receiving clozapine.

METHODS

This retrospective cohort study included patients with TRS who were initiated on clozapine during hospitalization and discharged between April 2012 and January 2021 in two tertiary psychiatric hospitals in Japan. Relapse was defined as rehospitalization due to psychiatric exacerbation during the first year after discharge. A multivariable Cox proportional hazards regression analysis was performed to analyze the effect of smoking habits and concomitant VPA use on relapse. Subgroup analyses were also conducted to examine potential interactions between smoking habits and concomitant VPA use.

RESULTS

Among the included 192 patients, 69 (35.9%) met the criteria of relapse. While smoking habits (adjusted hazard ratio [aHR], 2.27; 95% confidence interval [CI], 1.28-4.01; p < 0.01) independently increased the risk of relapse, a significant interaction for relapse risk was found between smoking habits and concomitant VPA use (p-interaction = 0.015). Concomitant VPA use may be an effective modifier of the increased relapse risk associated with smoking habits. Among patients who smoked, those using VPA concomitantly exhibited a higher risk of relapse (aHR, 5.32; 95% CI, 1.68-16.9; p < 0.01) than those not using VPA (aHR, 1.41; 95% CI, 0.73-2.70; p = 0.30).

CONCLUSION

The findings suggest that the combination of smoking habits and concomitant VPA use may increase the risk of relapse after discharge. Future studies are required to elucidate the mechanisms underlying these findings, such as a decrease in clozapine blood levels.

Pharmacogenetic Guidelines for Psychotropic Drugs: Optimizing Prescriptions in Clinical Practice

The modalities for prescribing a psychotropic (dose and choice of molecule) are currently unsatisfactory, which can lead to a lack of efficacy of the treatment associated with prolonged exposure of the patient to the symptoms of his or her illness and the side effects of the molecule. In order to improve the quality of treatment prescription, a part of the current biomedical research is dedicated to the development of pharmacogenetic tools for individualized prescription. In this guideline, we will present the genes of interest with level 1 clinical recommendations according to PharmGKB for the two major families of psychotropics: antipsychotics and antidepressants. For antipsychotics, there are CYP2D6 and CYP3A4, and for antidepressants, CYP2B6, CYP2D6, and CYP2C19. The study will focus on describing the role of each gene, presenting the variants that cause functional changes, and discussing the implications for prescriptions in clinical practice.

Electroconvulsive therapy or clozapine for adolescents with treatment-resistant schizophrenia: an explorative analysis on symptom dimensions

OBJECTIVE

This study sought to compare pre-intervention patient characteristics and post-intervention outcomes in a naturalistic sample of adolescent inpatients with treatment-resistant psychotic symptoms who received either electroconvulsive therapy (ECT) or clozapine.

METHODS

Data of adolescents with schizophrenia/schizoaffective disorder receiving ECT or clozapine were retrospectively collected from two tertiary-care psychiatry-teaching university hospitals. Subscale scores of the Positive and Negative Symptom Scale (PANSS) factors were calculated according to the five-factor solution. Baseline demographics, illness characteristics, and post-intervention outcomes were compared.

RESULTS

There was no significant difference between patients receiving ECT (n = 13) and clozapine (n = 66) in terms of age, sex, and the duration of hospital stay. The ECT group more commonly had higher overall illness and aggression severity. Smoking was less frequent in the clozapine group. Baseline resistance/excitement symptom severity was significantly higher in the ECT group, while positive, negative, affect, disorganisation, and total symptom scores were not. Both interventions provided a significant reduction in PANSS scores with large effect sizes.

CONCLUSION

Both ECT and clozapine yielded high effectiveness rates in adolescents with treatment-resistant schizophrenia/schizoaffective disorder. Youth receiving ECT were generally more activated than those who received clozapine.

How do smoking, vaping, and nicotine affect people with epilepsy and seizures? A scoping review protocol

BACKGROUND

Epilepsy is a prevalent disease that requires personalized care to control seizures, reduce side effects, and ameliorate the burden of comorbidities. Smoking is a major cause of preventable death and disease. There is evidence that patients with epilepsy smoke at high rates and that smoking may increase seizure frequency. However, there is a lack systematically synthesized evidence on the interactions between epilepsy and seizures and smoking, tobacco use, vaping, and smoking cessation.

METHODS AND ANALYSIS

This scoping review protocol guided by the Joanna Briggs Institute Manual for Evidence Synthesis and the PRISMA Extension for Scoping Reviews will investigate what is known about the interactions between smoking and epilepsy. This review will include the population of persons with all types of epilepsy or seizures and examine an inclusive list of concepts including tobacco use, vaping, nicotine replacement, and smoking cessation. The MEDLINE, Embase, APA Psycinfo, CINAHL, Cochrane, Scopus, and Web of Science databases will be searched. Following systematic screening of records, data will be charted, synthesized, and summarized for presentation and publication.

ETHICS AND DISSEMINATION

No ethical approval is required for this literature-based study. The results of this scoping review will be submitted for publication in a peer-reviewed journal. This synthesis will be informative to clinicians and direct further research that may improve health outcomes for people with epilepsy.

REGISTRATION

This protocol is registered with the Open Science Framework (DOI: https://doi.org/10.17605/OSF.IO/D3ZK8).

Role of FKBP5 and its genetic mutations in stress-induced psychiatric disorders: an opportunity for drug discovery

Stress-induced mental health disorders are affecting many people around the world. However, effective drug therapy for curing psychiatric diseases does not occur sufficiently. Many neurotransmitters, hormones, and mechanisms are essential in regulating the body's stress response. One of the most critical components of the stress response system is the hypothalamus-pituitary-adrenal (HPA) axis. The FKBP prolyl isomerase 51 (FKBP51) protein is one of the main negative regulators of the HPA axis. FKBP51 negatively regulates the cortisol effects (the end product of the HPA axis) by inhibiting the interaction between glucocorticoid receptors (GRs) and cortisol, causing reduced transcription of downstream cortisol molecules. By regulating cortisol effects, the FKBP51 protein can indirectly regulate the sensitivity of the HPA axis to stressors. Previous studies have indicated the influence of FKBP5 gene mutations and epigenetic changes in different psychiatric diseases and drug responses and recommended the FKBP51 protein as a drug target and a biomarker for psychological disorders. In this review, we attempted to discuss the effects of the FKBP5 gene, its mutations on different psychiatric diseases, and drugs affecting the FKBP5 gene.

Analysis of clozapine-induced seizures using the Japanese Adverse Drug Event Report database

Among antipsychotics, clozapine is associated with a high risk of seizures. This study aimed to generate novel hypotheses regarding trends in the onset of clozapine-induced seizures using the JADER (Japanese Adverse Drug Event Report) database. Seizures were defined according to the Standardized MedDRA Queries (SMQ) for convulsions (SMQ20000079). Trends in the onset of clozapine-induced seizures were assessed using multivariate logistic regression analysis with covariates of sex, age, clozapine dose, antipsychotic polypharmacy, concomitant medications, and history of convulsive disorder. In addition, we assessed the time-to-onset of clozapine-induced seizures using the median time, interquartile range, and Weibull shape parameter. The JADER database registered 2,745 cases of adverse events with clozapine, and 1,784 cases were included in the analysis after excluding cases for which clinical information was not available. Medium (200-400 mg) and high (> 400 mg) doses of clozapine had a significantly higher reporting rate of seizures than low doses (< 200 mg) (adjusted reporting odds ratio [aROR] = 3.05, 95% confidence interval [CI]: 1.86-4.99 and aROR = 9.81, 95% CI: 6.06-15.89, respectively). Younger age, antipsychotic polypharmacy, and concomitant use of lithium were also significantly associated with reports of seizures. The time-to-onset analysis of 222 cases of clozapine-induced seizures showed that the median time was 134 (interquartile range, 72-295) days. The 95% CI of the WSP β-value for clozapine-induced seizures included 1 and was classified as a random failure type. In conclusion, the results suggest that clozapine-induced seizures are dose-dependent adverse events that should be monitored with consideration of the effects of age and concomitant medications. Further epidemiological research is needed to strengthen and validate our hypotheses.

Clozapine: Dose, Sex, Ethnicity, Smoking Habit, Age, Body Weight, and Plasma Clozapine and N -Desmethylclozapine (Norclozapine) Concentrations in Clinical Practice

BACKGROUND

Guidance on clozapine dosing in treatment refractory schizophrenia is based largely on data from young adult male White patients.

AIM

This study aimed to audit the plasma clozapine and N -desmethylclozapine (norclozapine) concentrations attained in male and female patients of different ethnicity and smoking habit.

METHOD

The effect of dose, sex, ethnicity, age, body weight, and smoking habit on plasma clozapine and norclozapine concentrations were studied using data from a therapeutic drug monitoring service, 1993 to 2017.

RESULTS

There were 371,610 samples (48,098 patients, 32,855 male). Ethnicity was recorded for 763 Afro-Caribbean, 536 Asian, and 7940 White patients. Males were prescribed significantly higher median doses than females but attained significantly lower median plasma clozapine and norclozapine concentrations. Asian and Afro-Caribbean males were prescribed significantly lower and higher median doses, respectively, than White males but attained significantly higher and lower median plasma clozapine and norclozapine concentrations, respectively. Data from 78,431 samples (23,516 patients) were analyzed using a linear mixed model. The predicted dose to attain a predose plasma clozapine concentration of 0.35 mg/L in a nonsmoking White male aged 40 years, with weight of 70 kg, and plasma clozapine-norclozapine ratio of 1.32 was 344 mg/d (95% confidence interval, 227-526 mg/d). The predicted dose was 33% higher and 20% lower in otherwise analogous Afro-Caribbean and Asian patients, respectively. In all cases, the predicted dose was increased by 36% in smokers and decreased by 22% in females.

CONCLUSIONS

Research is needed to further investigate the complex relationships between dose, sex, ethnicity, plasma clozapine and norclozapine concentrations, and clinical outcome such as weight gain.

A smoking cessation intervention for people with severe mental illness treated in ambulatory mental health care (KISMET): study protocol of a randomised controlled trial

BACKGROUND

Smoking among people with severe mental illness (SMI) is highly prevalent and strongly associated with poor physical health. Currently, evidence-based smoking cessation interventions are scarce and need to be integrated into current mental health care treatment guidelines and clinical practice. Therefore, the present study aims to evaluate the implementation and effectiveness of a smoking cessation intervention in comparison with usual care in people with SMI treated by Flexible Assertive Community Treatment (FACT) teams in the Netherlands.

METHODS

A pragmatic, cluster-randomised controlled trial with embedded process evaluation will be conducted. Randomisation will be performed at the level of FACT teams, which will be assigned to the KISMET intervention or a control group (care as usual). The intervention will include pharmacological treatment combined with behavioural counselling and peer support provided by trained mental health care professionals. The intervention was developed using a Delphi study, through which a consensus was reached on the core elements of the intervention. We aim to include a total of 318 people with SMI (aged 18-65 years) who smoke and desire to quit smoking. The primary outcome is smoking status, as verified by carbon monoxide measurements and self-report. The secondary outcomes are depression and anxiety, psychotic symptoms, physical fitness, cardiovascular risks, substance use, quality of life, and health-related self-efficacy at 12 months. Alongside the trial, a qualitative process evaluation will be conducted to evaluate the barriers to and facilitators of its implementation as well as the satisfaction and experiences of both patients and mental health care professionals.

DISCUSSION

The results of the KISMET trial will contribute to the evidence gap of effective smoking cessation interventions for people treated by FACT teams. Moreover, insights will be obtained regarding the implementation process of the intervention in current mental health care. The outcomes should advance the understanding of the interdependence of physical and mental health and the gradual integration of both within the mental health care system.

TRIAL REGISTRATION

Netherlands Trial Register, NTR9783. Registered on 18 October 2021.

Therapeutic monitoring of plasma clozapine and N-desmethylclozapine (norclozapine): practical considerations

Clozapine dose assessment in treatment-refractory schizophrenia is complicated. There is a narrow margin between an effective and a potentially toxic dose and wide inter-individual variation in clozapine metabolic capacity. Moreover, factors such as changes in smoking habit, infection/inflammation, co-prescription of certain drugs, notably fluvoxamine, and age alter the dose requirement within individuals. Therapeutic drug monitoring (TDM) of plasma clozapine and N-desmethylclozapine (norclozapine) can help assess adherence, guide dosage and guard against toxicity. This article gives an overview of clozapine pharmacokinetics and factors affecting clozapine dose requirements. It then outlines the procedures and processes of clozapine TDM, from taking the blood sample for laboratory assay or point-of-contact (finger-prick) testing (POCT) to interpreting and acting on the results.

Influence of Cigarette Smoking Habit on Clozapine-to-Norclozapine Ratio in Male Patients

Objective

This study aimed to evaluate the influence of cigarette smoking habit on the clozapine (CLZ)-to-norclozapine (norCLZ) ratio in male patients.

Methods

The sample consisted of plasma concentration of CLZ and norCLZ data set. The mean values of CLZ, norCLZ, and CLZ-to-norCLZ, between male patients who smoke versus nonsmokers were compared.

Findings

CLZ mean plasma level of 142 ± 80 ng/ml and 305 ± 159 ng/ml, norCLZ mean plasma level of 93 ± 72 ng/ml and 234 ± 62 ng/ml, and mean CLZ-to-norCLZ plasma level ratio of 2.1 ± 1.1 and 1.5 ± 0.5, were obtained respectively for male patients who smoke and nonsmokers.

Conclusion

This study has shown a significant decrease in CLZ and norCLZ plasma levels, and an increase in the CLZ-to-norCLZ ratio, in smokers as compared to nonsmokers, due to an increase in the clearance of CLZ and norCLZ by smoking induction of CYP 1A2 and glucuronidation by uridyl glucuronyl transferase enzymes (UGT), mainly UGT 1A4, respectively, as the most probable cause.

Drug metabolism and drug transport of the 100 most prescribed oral drugs

Safe and effective use of drugs requires an understanding of metabolism and transport. We identified the 100 most prescribed drugs in six countries and conducted a literature search on in vitro data to assess contribution of Phase I and II enzymes and drug transporters to metabolism and transport. Eighty-nine of the 100 drugs undergo drug metabolism or are known substrates for drug transporters. Phase I enzymes are involved in metabolism of 67 drugs, while Phase II enzymes mediate metabolism of 18 drugs. CYP3A4/5 is the most important Phase I enzyme involved in metabolism of 43 drugs followed by CYP2D6 (23 drugs), CYP2C9 (23 drugs), CYP2C19 (22 drugs), CYP1A2 (14 drugs) and CYP2C8 (11 drugs). More than half of the drugs (54 drugs) are known substrates for drug transporters. P-glycoprotein (P-gp) is known to be involved in transport of 30 drugs, while breast cancer resistance protein (BCRP) facilitates transport of 11 drugs. A considerable proportion of drugs are subject to a combination of Phase I metabolism, Phase II metabolism and/or drug transport. We conclude that the majority of the most frequently prescribed drugs depend on drug metabolism or drug transport. Thus, understanding variability of drug metabolism and transport remains a priority.

Impact of NFIB and CYP1A variants on clozapine serum concentration-A retrospective naturalistic cohort study on 526 patients with known smoking habits

Clinical response of clozapine is closely associated with serum concentration. Although tobacco smoking is the key environmental factor underlying interindividual variability in clozapine metabolism, recent genome-wide studies suggest that CYP1A and NFIB genetic variants may also be of significant importance, but their quantitative impact is unclear. We investigated the effects of the rs2472297 C>T (CYP1A) and rs28379954 T>C (NFIB) polymorphisms on serum concentrations in smokers and nonsmokers. The study retrospectively included 526 patients with known smoking habits (63.7% smokers) from a therapeutic drug monitoring service in Norway. Clozapine dose-adjusted concentrations (C/D) and patient proportions with subtherapeutic levels (<1070 nmol/L) were compared between CYP1A/NFIB variant allele carriers and homozygous wild-type carriers (noncarriers), in both smokers and nonsmokers. Clozapine C/D was reduced in patients carrying CYP1A-T and NFIB-C variants versus noncarriers, both among smokers (-48%; p < 0.0001) and nonsmokers (-35%; p = 0.028). Patients who smoke carrying CYP1A-T and NFIB-C variants had a 66% reduction in clozapine C/D versus nonsmoking noncarriers (p < 0.0001). The patient proportion with subtherapeutic levels was 2.9-fold higher in patients who smoke carrying NFIB-C and CYP1A-T variants versus nonsmoking noncarriers (p < 0.0001). In conclusion, CYP1A and NFIB variants have significant and additive impact on clozapine dose requirements for reaching target serum concentrations. Patients who smoke carrying the studied CYP1A and NFIB variants, comprising 2.5% of the study population, may need threefold higher doses to prevent risk of clozapine undertreatment. The results suggest that pre-emptive genotyping of NFIB and CYP1A may be utilized to guide clozapine dosing and improve clinical outcomes in patients with treatment-resistant schizophrenia.

Prescribing clozapine in the UK: Quality improvement issues identified by clinical audit

INTRODUCTION

The Prescribing Observatory for Mental Health initiated a quality improvement (QI) programme on clozapine use in UK mental health services.

METHODS

Clinical audits conducted in 2019 and 2021.

RESULTS

Sixty-three participating NHS Trusts/healthcare organisations in 2019, and 61 in 2021, submitted treatment data for 6948 and 8155 patients, respectively. In both audits, high-dose and/or combined antipsychotic medications had been prescribed immediately before initiating clozapine in over a quarter of patients recently started on clozapine. In patients who were tobacco smokers and recently discharged from a smoke-free ward, the impact of the potential change in smoking status had been considered in the care plans of just under one-third in 2019 and just over a half in 2021. For community patients, their Summary Care Records (SCRs) included their clozapine prescriptions in 58% of cases in 2019 and 72% in 2021.

CONCLUSIONS

Three QI issues were identified. (1) Antipsychotic regimens with limited evidence for efficacy in treatment-resistant schizophrenia were prescribed for over a quarter of cases before starting clozapine. Use of such strategies may delay clozapine treatment, potentially reducing the likelihood of a therapeutic response. (2) While anticipation of the consequences of a change in smoking status on plasma clozapine concentration following discharge from hospital showed improvement over time, even in 2021 it was not evident for nearly a half of relevant cases. (3) While inclusion of clozapine in the SCR also improved over time, even in 2021 it was missing for more than a quarter of community patients.

Place of the partial dopamine receptor agonist aripiprazole in the management of schizophrenia in adults: a Delphi consensus study

BACKGROUND

Aripiprazole is a second-generation antipsychotic, efficacious in patients with schizophrenia during acute episodes. Due to its pharmacological profile, aripiprazole may be of interest in patients with specific clinical profiles who have not been studied extensively in randomised clinical trials.

OBJECTIVES

To capture experience with aripiprazole in everyday psychiatric practice using the Delphi method in order to inform decision-making on the use of aripiprazole for the treatment of patients with schizophrenia in clinical situations where robust evidence from clinical trials is lacking.

METHODS

The scope of the survey was defined as the management of schizophrenia in adults. A systematic literature review was performed to identify the different clinical situations in which aripiprazole has been studied, and to describe the level of clinical evidence. Clinical profiles to include in the Delphi survey were selected if there was a clear interest in terms of medical need but uncertainty over the efficacy of aripiprazole. For each clinical profile retained, five to seven specific statements were generated and included in a questionnaire. The final 41-item questionnaire was proposed to a panel of 406 French psychiatrists with experience in the treatment of schizophrenia. Panellists rated their level of agreement using a Likert scale. A second round of voting on eleven items was organised to clarify points for which a consensus was not obtained in the first round.

RESULTS

Five clinical profiles were identified in the literature review (persistent negative symptoms, pregnancy, cognitive dysfunction, addictive comorbidity and clozapine resistance). Sixty-two psychiatrists participated in the first round of the Delphi survey and 33 in the second round. A consensus was obtained for 11 out of 41 items in the first round and for 9/11 items in the second round. According to the panellists' clinical experience, aripiprazole can be used as maintenance treatment for pregnant women, is relevant to preserve cognitive function and can be considered an option in patients with a comorbid addictive disorder or with persistent negative symptoms.

CONCLUSION

These findings may help physicians in choosing relevant ways to use aripiprazole and highlight areas where more research is needed to widen the evidence base.

Treatment resistance in psychiatry: state of the art and new directions

Treatment resistance affects 20-60% of patients with psychiatric disorders; and is associated with increased healthcare burden and costs up to ten-fold higher relative to patients in general. Whilst there has been a recent increase in the proportion of psychiatric research focussing on treatment resistance (R² = 0.71, p < 0.0001), in absolute terms this is less than 1% of the total output and grossly out of proportion to its prevalence and impact. Here, we provide an overview of treatment resistance, considering its conceptualisation, assessment, epidemiology, impact, and common neurobiological models. We also review new treatments in development and future directions. We identify 23 consensus guidelines on its definition, covering schizophrenia, major depressive disorder, bipolar affective disorder, and obsessive compulsive disorder (OCD). This shows three core components to its definition, but also identifies heterogeneity and lack of criteria for a number of disorders, including panic disorder, post-traumatic stress disorder, and substance dependence. We provide a reporting check-list to aid comparisons across studies. We consider the concept of pseudo-resistance, linked to poor adherence or other factors, and provide an algorithm for the clinical assessment of treatment resistance. We identify nine drugs and a number of non-pharmacological approaches being developed for treatment resistance across schizophrenia, major depressive disorder, bipolar affective disorder, and OCD. Key outstanding issues for treatment resistance include heterogeneity and absence of consensus criteria, poor understanding of neurobiology, under-investment, and lack of treatments. We make recommendations to address these issues, including harmonisation of definitions, and research into the mechanisms and novel interventions to enable targeted and personalised therapeutic approaches.