Clozapine Rechallenge After Major Adverse Effects: Clinical Guidelines Based on 259 Cases

A Review of Clinical Advances and Challenges in Clozapine-Induced Myocarditis

Currently, the treatment of schizophrenia remains primarily pharmacological, with approximately 30% of patients diagnosed with treatment-resistant schizophrenia (TRS). Clozapine continues to be the first choice treatment for this subgroup of patients. As the preferred treatment, clozapine offers clear advantages in efficacy; however, its complex and troublesome adverse effects pose significant challenges for psychiatrists. Common side effects include granulocytopenia, intestinal obstruction, myocarditis, cardiomyopathy, constipation, and seizures. The first two complications are easier to manage due to the availability of laboratory monitoring, and improved management strategies are now in place in clinical practice. In recent years, clozapine-induced myocarditis (CIM) has gained considerable attention because of its potentially severe outcomes. However, the mechanism behind its lethality remains unclear, and there is no widely accepted consensus or treatment guideline, which complicates the implementation of targeted prevention in clinical practice. This review aims to summarize the clinical manifestations of CIM, explore the underlying mechanisms, and discuss recent advances in monitoring, diagnosis, and treatment, with the goal of offering constructive recommendations for future clinical management.

When, Why and How to Re-challenge Clozapine in Schizophrenia Following Myocarditis

Clozapine-induced myocarditis (CIM) is among the most important adverse events limiting the use of clozapine as the most effective treatment for schizophrenia. CIM necessitates the immediate termination of clozapine, often resulting in its permanent discontinuation with considerable detrimental effects on patients' psychopathology and long-term outcome. Consequently, a clozapine re-challenge after CIM is increasingly regarded as a viable alternative, with published reports indicating a success rate of approximately 60%. However, published cases of re-challenges after CIM remain limited. Here, we provide a narrative review of the current state of research regarding the epidemiology, pathophysiology, risk factors, diagnosis and clinical management of CIM as well as a synthesis of current recommendations for re-challenging patients after CIM. This includes a step-by-step guide for this crucial procedure based on the current evidence regarding the pathophysiology and risk factors for CIM. Slow dose titration regimes and addressing risk factors including concomitant valproate and olanzapine are crucial both to prevent CIM and to ensure a safe and successful re-challenge. Furthermore, we discuss the utility of C-reactive protein, troponin, N-terminal-pro hormone and brain natriuretic peptide, therapeutic drug-monitoring and cardiac magnetic resonance imaging for CIM screening and diagnosis as well as for post-CIM re-challenges.

Understanding clozapine-related blood dyscrasias. Developments, genetics, ethnicity and disparity: it's a CIN

Clozapine remains the gold standard intervention for treatment-resistant schizophrenia; however, it remains underused, especially for some minority groups. A significant impediment is concern about propensity to neutropenia. The aim of this article is to provide an update on current knowledge relating to: the pattern and incidence of severe blood dyscrasias; the effectiveness of current monitoring regimes in reducing harm; the mechanisms of and the distinctions between clozapine-induced neutropenia and agranulocytosis; benign ethnic neutropenia; and changes to the monitoring thresholds in the USA and other international variations. These all have implications for the practical use of clozapine; specifically, how barriers to initiating, maintaining and restarting clozapine can be understood and in many cases overcome, especially for patients from minority groups, potentially with simpler approaches than the use of lithium or G-CSF.

Risk of clozapine-associated agranulocytosis and mandatory white blood cell monitoring: Can the regulations be relaxed?

After the introduction of clozapine eight Finnish patients died after developing agranulocytosis. Clozapine was withdrawn from the market and only reintroduced with strict mandatory white blood cell monitoring as long as treatment lasts and thresholds at which clozapine must be discontinued definitively. The fear of agranulocytosis and the need for intensive blood monitoring is the single most important barrier for prescribers and patients alike and leads to underprescription of the only effective and approved medication for treatment-resistant schizophrenia. We summarize evidence that the risk of agranulocytosis is smaller than perceived at the time of reintroduction, is concentrated in the first 18 weeks of treatment, is not greater than with other antipsychotics thereafter and that frequent blood monitoring has not demonstrably decreased the rate of agranulocytosis. Therefore we propose 1) mandatory monitoring of the absolute neutrophil count (ANC) exclusively during the first 18 weeks of clozapine treatment, 2) that thereafter the prescriber and the well-informed patient decide together about further monitoring frequency, 3) that clozapine treatment must be stopped if the ANC falls below 1.0 × 109/L. Continuation of clozapine or a rechallenge are possible if prescriber and patient determine that the benefits outweigh the risks. 4) National registries which control the haematologic monitoring are unnecessary and do not help to reduce clozapine-induced agranulocytosis. They should at least be restricted to the first 18 weeks of clozapine use.

Successful Clozapine Rechallenge After Clozapine-Induced Severe Anemia: A Case Report

INTRODUCTION

Clozapine, a second-generation antipsychotic (SGA), is considered the gold standard medication to treat patients with treatment-resistant schizophrenia (TRS). Despite its efficacy, clozapine is associated with adverse effects, notably neutropenia and agranulocytosis. Other hematological adverse effects are less common. Severe anemia is a rare adverse effect seldom reported in the literature and is typically associated with pure red cell aplasia (PRCA). Nevertheless, the benefits of clozapine in managing TRS make rechallenge a reasonable option.

CASE REPORT

We present the case of a 35-year-old man with TRS, resistant to previous antipsychotics, who experienced severe anemia during clozapine treatment. An investigation for clozapine-induced anemia revealed PRCA on myelogram. After discontinuing clozapine, the patient's hemoglobin levels recovered. Subsequent treatments with olanzapine, zuclopenthixol, and aripiprazole proved ineffective, leading us to consider a clozapine rechallenge. The rechallenge, monitored for 58 days, resulted in improved psychiatric symptoms and stable hemoglobin levels. The patient remained stable during 6 months of follow-up, with no hematological changes.

DISCUSSION

PRCA is a very rare adverse effect of clozapine. The cause of drug-induced PRCA is still unknown; for clozapine, there are no studies. Rechallenge after a severe and rare adverse effect is a complex decision. This case is the first to report a successful clozapine rechallenge following severe anemia without other blood dyscrasias, emphasizing the imperative need for close monitoring during the rechallenge process. Further study is warranted to understand the predictive factors for a successful outcome in clozapine rechallenges.

Abnormal blood concentration changes in a 71-year-old female who survived a 10,000mg overdose of clozapine: a case report

BACKGROUND

Clozapine is a highly effective second-generation antipsychotic with few extrapyramidal reactions, making it a preferred choice among clinicians. However, instances of acute clozapine poisoning resulting from suicide attempts and misuse have been reported. Through our review of existing literature, we identified that we believe to be the highest recorded overdose of clozapine in elderly patients, resulting in a nonfatal outcome.

CASE PRESENTATION

The case report involves a 71-year-old female with a history of depression who ingested a dose of 10,000 mg of clozapine. Approximately 6 h after the overdose, the clozapine level was 5,200 μg/L, significantly surpassing the recommended therapeutic concentration range of 350-600 μg/L. After gastric lavage and hemoperfusion, the blood level dropped to 1847.11 μg/L. Notably, during therapeutic drugs monitoring (TDM), we found a perplexing spike in the patient's blood level to 5554.15 μg/L after the second hemoperfusion.

CONCLUSION

In this case we mainly focused on the abnormal fluctuations in the concentration of clozapine. We conducted a comprehensive analysis of potential factors contributing to this abnormal phenomenon in terms of the patient's age, clinical symptoms, various laboratory test indexes, and the pharmacokinetics of clozapine. Our findings underscore the importance of timely TDM and the precision of results in managing elderly patients experiencing high-dose clozapine poisoning.

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.

[Safety aspects during treatment with clozapine. : Monitoring and rechallenge - a narrative review]

BACKGROUND

Due to its unique efficacy in treatment-resistant schizophrenia, discontinuation of treatment with clozapine is frequently associated with a significant worsening of symptoms, but also with an increased risk of suicide. Based on the literature, this review aims at summarizing different monitoring recommendations in order to be able to continue this therapy despite the occurrence of side effects. In addition, we provide recommendations when rechallenge of a previously stopped treatment with clozapine can be considered and when a definite discontinuation must take place.

MATERIAL AND METHODS

Medline, the Guideline for the use of clozapine 2013 of the Netherlands Clozapine Collaboration Group, and the S3 Guideline for Schizophrenia of the German Association of Psychiatry, Psychotherapy and Psychosomatics were searched for relevant literature, the last query dating from April 28th, 2023.

RESULTS

If agranulocytosis or cardiomyopathy develops, treatment with clozapine must be discontinued and should not be resumed thereafter. In contrast, treatment with clozapine which had to be discontinued due to myocarditis or prolongation of the QTc interval may be continued if left ventricular function is normal or after normalization of the QTc interval. Other side effects are usually not absolute contraindications for rechallenge but often require the adjunctive use of additional pharmacologic and non-pharmacologic measures.

CONCLUSION

Taking into consideration various monitoring recommendations, cessation of treatment with clozapine can often be prevented or treatment with clozapine that has been discontinued due to side effects can be resumed.

Second to none: rationale, timing, and clinical management of clozapine use in schizophrenia

Despite its enduring relevance as the single most effective and important evidence-based treatment for schizophrenia, underutilization of clozapine remains considerable. To a substantial degree, this is attributable to a reluctance of psychiatrists to offer clozapine due to its relatively large side-effect burden and the complexity of its use. This underscores the necessity for continued education regarding both the vital nature and the intricacies of clozapine treatment. This narrative review summarizes all clinically relevant areas of evidence, which support clozapine's wide-ranging superior efficacy - for treatment-resistant schizophrenia (TRS) and beyond - and make its safe use eminently feasible. Converging evidence indicates that TRS constitutes a distinct albeit heterogeneous subgroup of schizophrenias primarily responsive to clozapine. Most importantly, the predominantly early onset of treatment resistance and the considerable decline in response rates associated with its delayed initiation make clozapine an essential treatment option throughout the course of illness, beginning with the first psychotic episode. To maximize patients' benefits, systematic early recognition efforts based on stringent use of TRS criteria, a timely offer of clozapine, thorough side-effect screening and management as well as consistent use of therapeutic drug monitoring and established augmentation strategies for suboptimal responders are crucial. To minimize permanent all-cause discontinuation, re-challenges after neutropenia or myocarditis should be considered. Owing to clozapine's unique efficacy, comorbid conditions including substance use and most somatic disorders should not dissuade but rather encourage clinicians to consider clozapine. Moreover, treatment decisions need to be informed by the late onset of clozapine's full effects, which for reduced suicidality and mortality rates may not even be readily apparent. Overall, the singular extent of its efficacy combined with the high level of patient satisfaction continues to distinguish clozapine from all other available antipsychotics.

Myocarditis in patients on long-term antipsychotics -mechanism, management and recent updates

Objective

Clozapine is the first atypical antipsychotic drug and was frequently cited as the most effective antipsychotic for treatment-resistant schizophrenia, but it is associated with a concert of significant cardiotoxic side effects. Clozapine-induced Myocarditis (CIM) is diagnosed based on the combination of clinical symptoms, laboratory investigations, radiological findings, and sometimes biopsy. The literature on CIM management and clinical consensus on the best course of action is mixed.

Methodology

An all-language literature search on Medline, Cochrane, Embase, and Google Scholar until April 2022. The following search strings and Medical Subject Heading (MeSH) terms were used: "CIM," "clozapine," "cardiotoxicity," and "myocarditis." We explored the literature on CIM for its pathophysiology, diagnosis, monitoring, and management.

Results

The clinical features of CIM may be highly variable, ranging from asymptomatic disease to fulminant heart failure, and cessation of medication was the mainstay treatment of CIM, followed by supportive therapy. Other antipsychotics have also been linked with cardiotoxic side effects.

Conclusion

Despite being the most effective antipsychotic, clozapine is associated with a cardiotoxic side effect. Current literature suggests that these antipsychotic-related cardiotoxic events impact the treatment selection for schizophrenia and other psychotic disorders, and they must be kept in mind while designing new treatment protocols in the future.

Clozapine is the approved option in treatment-resistant schizophrenia and requires careful management

Clozapine is the only agent approved for treatment-resistant schizophrenia, but is underprescribed. Its adverse drug event (ADE) profile and patient monitoring requirements can discourage its use, but the benefits of clozapine generally outweigh its risks, as most ADEs are manageable. Careful patient assessment, gradual titration, minimum effective dosages, therapeutic drug monitoring and checks of neutrophils, cardiac enzymes and ADE symptoms are recommended. Neutropenia is common but does not necessarily warrant permanent clozapine cessation.

Drug-drug interactions involving combinations of antipsychotic agents with antidiabetic, lipid-lowering, and weight loss drugs

INTRODUCTION

Patients with severe mental illness (SMI) have a high risk for diabetes, dyslipidemia, and other components of metabolic syndrome. Patients with these metabolic comorbidities and cardiac risk factors should receive not only antipsychotics but also medications aiming to reduce cardiovascular risk. Therefore, many patients may be exposed to clinically relevant drug-drug interactions.

AREAS COVERED

This narrative review summarizes data regarding the known or potential drug-drug interactions between antipsychotics and medications treating metabolic syndrome components, except for hypertension, which has been summarized elsewhere. A literature search in PubMed and Scopus up to 7/31/2021 was performed regarding interactions between antipsychotics and drugs used to treat metabolic syndrome components, aiming to inform clinicians' choice of medication for patients with SMI and cardiometabolic risk factors in need of pharmacologic interventions.

EXPERT OPINION

The cytochrome P450 system and, to a lesser extent, the P-glycoprotein transporter is involved in the pharmacokinetic interactions between antipsychotics and some statins or saxagliptin. Regarding pharmacodynamic interactions, the available information is based mostly on small studies, and for newer classes, like PCSK9 inhibitors or SGLT2 inhibitors, data are still lacking. However, there is sufficient information to guide clinicians in the process of selecting safer antipsychotic-cardiometabolic risk reduction drug combinations.

Successful rechallenge with clozapine after discontinuation due to drug-induced pneumonia: A case report

Background

There have been a limited number of case reports of clozapine-induced pneumonia. Few have reported rechallenging of clozapine after discontinuation due to the side-effect.

Case Presentation

A 43-year-old man was diagnosed with schizophrenia after developing auditory hallucinations and delusions of persecution and reference. After diagnosing him with treatment-resistant schizophrenia, clozapine was started. From a starting dose of 12.5 mg/day, we increased it by 25 mg every 2-3 days to reach 150 mg/day by Day 15. On Day 17, his body temperature suddenly rose to 39.6°C (103.3°F) without any other apparent physical symptoms. Blood biochemistry testing showed elevated C-reactive protein (CRP) and high counts of leukocytes and neutrophils, but not eosinophils. Chest computed tomography revealed ground-glass opacities in the lower lobes of both lungs. Suspecting bacterial pneumonia, we started him on levofloxacin 500 mg/day. However, pneumonia exacerbated, and eosinophilia became apparent 5 days after the onset of fever. We suspected acute eosinophilic pneumonia induced by clozapine and discontinued its administration the same day. The patient clinically recovered the next day after stopping clozapine. After stopping clozapine, his psychiatric symptoms, such as persecutory/referential delusions, irritability, and polydipsia, became worse. We decided to rechallenge with clozapine in incremental doses slower than the standard protocol, along with careful monitoring of CRP and eosinophil counts. Pneumonia has not recurred, and his psychiatric symptoms have been well managed.

Conclusion

Our experience suggests that some patients with inflammatory reactions to clozapine can still take the drug if it is reintroduced with caution.

Clozapine's multiple cellular mechanisms: What do we know after more than fifty years? A systematic review and critical assessment of translational mechanisms relevant for innovative strategies in treatment-resistant schizophrenia

Almost fifty years after its first introduction into clinical care, clozapine remains the only evidence-based pharmacological option for treatment-resistant schizophrenia (TRS), which affects approximately 30% of patients with schizophrenia. Despite the long-time experience with clozapine, the specific mechanism of action (MOA) responsible for its superior efficacy among antipsychotics is still elusive, both at the receptor and intracellular signaling level. This systematic review is aimed at critically assessing the role and specific relevance of clozapine's multimodal actions, dissecting those mechanisms that under a translational perspective could shed light on molecular targets worth to be considered for further innovative antipsychotic development. In vivo and in vitro preclinical findings, supported by innovative techniques and methods, together with pharmacogenomic and in vivo functional studies, point to multiple and possibly overlapping MOAs. To better explore this crucial issue, the specific affinity for 5-HT₂R, D1R, α_2c, and muscarinic receptors, the relatively low occupancy at dopamine D2R, the interaction with receptor dimers, as well as the potential confounder effects resulting in biased ligand action, and lastly, the role of the moiety responsible for lipophilic and alkaline features of clozapine are highlighted. Finally, the role of transcription and protein changes at the synaptic level, and the possibility that clozapine can directly impact synaptic architecture are addressed. Although clozapine's exact MOAs that contribute to its unique efficacy and some of its severe adverse effects have not been fully understood, relevant information can be gleaned from recent mechanistic understandings that may help design much needed additional therapeutic strategies for TRS.

Clozapine Rechallenge or Continuation Despite Neutropenia, an Extended Follow-up of a Consecutive Quebec Case Series

BACKGROUND

Clozapine is the most efficacious antipsychotic for treatment-resistant schizophrenia. However, clozapine-induced neutropenia may warrant treatment discontinuation, hindering recovery. Several case reports describe clozapine rechallenge or continuation despite neutropenia, although many are subject to selective reporting, with incomplete information and short follow-up periods. Thus, consecutive case series, devoid of such bias, with long-term comprehensive follow-up are needed to better assess this practice. This study aimed to describe consecutively the evolution of every patient in the Québec City catchment area for whom clozapine was either reintroduced after neutropenia during a previous clozapine trial or was maintained despite a first neutropenia.

METHODS

Patients were identified through clozapine's national hematological monitoring database and their medical records between January 1, 2000, and October 22, 2017.

RESULTS

Twenty-three patients were identified, 8 continued clozapine despite neutropenia, while 15 discontinued clozapine and attempted rechallenge; among the latter, 4 patients were successfully rechallenged after agranulocytosis without the use of granulocyte colony-stimulating factors, which is the largest published consecutively. A total of 6 patients experienced further neutropenia episodes. Every patient who had a neutropenia recurrence also had a possible explanation for neutropenia other than exposure to clozapine. After a median follow-up of 4.8 years, 16 patients were still on clozapine and 3 cases discontinued because of a hematological event.

CONCLUSIONS

This study adds further data on the subject of clozapine rechallenge or continuation despite neutropenia. Clozapine rechallenge after agranulocytosis may be less perilous than first thought, but a systematic review on this specific subject is needed.

A Guideline and Checklist for Initiating and Managing Clozapine Treatment in Patients with Treatment-Resistant Schizophrenia

Treatment-resistant schizophrenia (TRS) will affect about one in three patients with schizophrenia. Clozapine is the only treatment approved for TRS, and patients should be treated as soon as possible to improve their chances of achieving remission. Despite its effectiveness, concern over side effects, monitoring requirements, and inexperience with prescribing often result in long delays that can expose patients to unnecessary risks and compromise their chances of achieving favorable long-term outcomes. We critically reviewed the literature on clozapine use in TRS, focusing on guidelines, systematic reviews, and algorithms to identify strategies for improving clozapine safety and tolerability. Based on this, we have provided an overview of strategies to support early initiation of clozapine in patients with TRS based on the latest evidence and our clinical experience, and have summarized the key elements in a practical, evidence-based checklist for identifying and managing patients with TRS, with the aim of increasing confidence in prescribing and monitoring clozapine therapy.

Successful clozapine rechallenge after myopericarditis: a case report

Clozapine-induced myocarditis and pericarditis are uncommon adverse effects of clozapine treatment. However, in most cases, they lead to clozapine discontinuation. Here, we describe a case of successful clozapine rechallenge after clozapine-induced myopericarditis. The patient, a 31-year-old male with treatment-resistant schizophrenia (TRS), developed dyspnea on exertion and chest pain on day 19 after the start of clozapine titration. An electrocardiogram (ECG) showed widespread, mild, convex ST interval elevation. While troponin levels were mildly elevated, the echocardiogram was unremarkable. A myopericarditis diagnosis was formulated, and clozapine was stopped, with a progressive resolution of clinical, laboratory and ECG abnormalities. After 6 months, a rechallenge with clozapine was attempted. A very slow titration scheme was adopted, along with close monitoring of clinical, laboratory and ECG parameters. Clozapine target dose was reached without the occurrence of any abnormality. Given the unique role of clozapine in the management of TRS, clozapine rechallenge may be considered after pericarditis, even with troponin levels elevation. Further studies are needed to update current clinical guidelines.

Successful rechallenge after clozapine-associated myocarditis

Clozapine is a highly effective medication used in management of treatment-resistant schizophrenia. Clozapine-associated myocarditis (CAM) is a rare but increasingly recognised complication of clozapine titration. Following an episode of CAM, clinicians can face a challenging dilemma of balancing the risks of recurrent myocarditis against the harms of ongoing psychosis. We describe the case of a woman in her 60s who developed acute myocarditis during clozapine titration and was then cautiously rechallenged with a successful outcome.

Transient Clozapine-induced Myocarditis Without Discontinuation of Medication: A Series of 2 Patients

BACKGROUND

Clozapine, an antipsychotic medication used to treat treatment-refractory schizophrenia, has been associated with various dangerous side effects, including myocarditis. However, there have been few published cases reporting on patients with clozapine-induced myocarditis confirmed by cardiac magnetic resonance imaging or the management, treatment, and follow-up of these patients.

METHODS

This report describes 2 cases of patients with treatment-refractory schizophrenia evidencing transient clozapine-induced myocarditis. Detailed information including laboratory values, imaging results, and clinical notes were gathered.

FINDINGS

The 2 cases demonstrated differing manifestations of clozapine-induced myocarditis. Both cases showed that such myocarditis can be transient and can be treated clinically with close observation without discontinuation of clozapine.

IMPLICATIONS

These cases show that clozapine-induced myocarditis is transient at times and can self-resolve without discontinuation of clozapine. These observations may suggest a change in clinical practice so that, with close observation, we can avoid risking psychiatric decompensation in select patients with a history of treatment-resistant schizophrenia.

Demographic and clinical characteristics of patients who recommence clozapine following therapy interruptions

OBJECTIVE

The proportion of patients who recommence clozapine after cessation, the time taken to resume clozapine post-cessation, and distinguishing demographic and clinical characteristics of this group have been poorly researched. We evaluated these in the current study.

METHOD

We retrospectively extracted selected demographic and clinical variables and clozapine treatment interruption and recommencement data up to December 2018 of a cohort of 458 patients who first commenced clozapine between 2006 and 2016. The study was conducted at three Australian health services.

RESULTS

Of the 310 (69%) patients who had at least one interruption of clozapine treatment, 170 (54.8%) did not resume clozapine, and 140 (45.2%) recommenced it after the first interruption. More than half of those who recommenced did so within a month and 80% by 12 months. Cox regression analysis revealed that age was significantly associated with recommencement, with a 2% decrease in the likelihood of restarting after an interruption for each year later that clozapine was initially commenced (HR = 0.98 95%CI: 0.97, 0.997, p = 0.02). Those who ceased clozapine due to adverse effects were less likely to restart than those who ceased due to noncompliance (HR = 0.63 95%CI: 0.41, 0.97, p = 0.03). More time on clozapine prior to interruption increased the likelihood of restarting it, with each additional month on clozapine increasing this likelihood by 1% (HR = 1.01 95%CI: 1.01, 1.02, p < 0.001).

CONCLUSION

If the distinguishing demographic and clinical characteristics of the group identified in this study are corroborated through further research, this could further validate the need to identify treatment resistance and commence clozapine early in people with schizophrenia and provide appropriate interventions to those more at risk of permanent discontinuation of clozapine.

Prevalence and clinical characteristics of COVID-19 in inpatients with schizophrenia in Wuhan, China

BACKGROUND

In contrast to many Western countries, China has maintained its large psychiatric hospitals. The prevalence and clinical characteristics of coronavirus disease 2019 (COVID-19) in inpatients with schizophrenia (SCZ) are unclear.

AIM

To assess the prevalence of COVID-19 among inpatients with SCZ and compare the infected to uninfected SCZ patients in a Wuhan psychiatric hospital.

METHODS

We retrospectively collected demographic characteristics and clinical profiles of all SCZ patients with COVID-19 at Wuhan’s Youfu Hospital.

RESULTS

Among the 504 SCZ patients, 84 had COVID-19, and we randomly sampled 174 who were uninfected as a comparison group. The overall prevalence of COVID-19 in SCZ patients was 16.7%. Among the 84 SCZ patients with confirmed COVID-19, the median age was 54 years and 76.2% were male. The most common symptom was fever (82%), and less common symptoms were cough (31%), poor appetite (20%), and fatigue (16%). Compared with SCZ patients without COVID-19, those with COVID-19 were older (P = 0.006) and significantly lighter (P = 0.002), and had more comorbid physical diseases (P = 0.001). Surprisingly, those infected were less likely to be smokers (< 0.001) or to be treated with clozapine (P = 0.03). Further logistic regression showed that smoking [odds ratio (OR) = 5.61], clozapine treated (OR = 2.95), and male (OR = 3.48) patients with relatively fewer comorbid physical diseases (OR = 0.098) were at a lower risk for COVID-19. SCZ patients with COVID-19 presented primarily with fever, but only one-third had a cough, which might otherwise be the most common mode of transmission between individuals.

CONCLUSION

Two unexpected protective factors for COVID-19 among SCZ inpatients are smoking and clozapine treatment.

Clozapine-induced myocarditis: electronic health register analysis of incidence, timing, clinical markers and diagnostic accuracy

BACKGROUND

Clozapine is associated with increased risk of myocarditis. However, many common side-effects of clozapine overlap with the clinical manifestations of myocarditis. As a result, there is uncertainty about which signs, symptoms and investigations are important in distinguishing myocarditis from benign adverse effects of clozapine. Clarity on this issue is important, since missing a diagnosis of myocarditis or discontinuing clozapine unnecessarily may both have devastating consequences.

AIMS

To examine the clinical characteristics of clozapine-induced myocarditis and to identify which signs and symptoms distinguish true myocarditis from other clozapine adverse effects.

METHOD

A retrospective analysis of the record database for 247 621 patients was performed. A natural language processing algorithm identified the instances of patients in which myocarditis was suspected. The anonymised case notes for the patients of each suspected instance were then manually examined, and those whose instances were ambiguous were referred for an independent assessment by up to three cardiologists. Patients with suspected instances were classified as having confirmed myocarditis, myocarditis ruled out or undetermined.

RESULTS

Of 254 instances in 228 patients with suspected myocarditis, 11.4% (n = 29 instances) were confirmed as probable myocarditis. Troponin and C-reactive protein (CRP) had excellent diagnostic value (area under the curve 0.975 and 0.896, respectively), whereas tachycardia was of little diagnostic value. All confirmed instances occurred within 42 days of clozapine initiation.

CONCLUSIONS

Suspicion of myocarditis can lead to unnecessary discontinuation of clozapine. The 'critical period' for myocarditis emergence is the first 6 weeks, and clinical signs including tachycardia are of low specificity. Elevated CRP and troponin are the best markers for the need for further evaluation.

Clozapine-induced myocarditis and patient outcomes after drug rechallenge following myocarditis: A systematic case review

Clozapine is underutilized due, in part, to concerns about rare but severe adverse drug reactions, including cardiac inflammation and injury (myocarditis). Risk factors for clozapine-induced myocarditis are limited and predictors for the successful rechallenge of clozapine after an episode of myocarditis are even more poorly understood. We conducted a systematic review, in accordance with the PRISMA recommendation, of published case reports to describe demographic and clinical characteristics of patients with clozapine-induced myocarditis and identify potential markers of clozapine rechallenge success. A total of 180 cases from 88 articles were evaluated. Male cases of clozapine-associated myocarditis were more frequently reported than female cases by a ratio of 6:1. Less than half of patients reported the presence of chest pain (35%) or flu-like symptoms (43%) but increases in troponin or C-reactive protein were present in 87% of cases. Clozapine rechallenge was carried out in 34 (2 female) cases, with successful reintroduction in 22 (2 female) cases (64.7%) and one fatality (2.9%). No demographic or clinical markers were significantly associated with rechallenge success after correction for multiple testing. Standardized reporting of clozapine-induced myocarditis cases is needed to facilitate the identification of factors associated with successful rechallenge.

Clozapine rechallenge following neutropenia using granulocyte colony-stimulating factor: A Quebec case series

BACKGROUND

Clozapine has a unique efficacy profile among individuals suffering from treatment-resistant schizophrenia, but is associated with hematological side effects. The use of granulocyte colony-stimulating factors (G-CSF) to allow clozapine continuation or rechallenge has emerged as a promising option, but evidence is still scarce.

AIM

To describe the largest case series so far published regarding this practice.

METHOD

A national clozapine hematological monitoring database was consulted to identify all patients who had had neutrophil count <1.5 × 10⁹/L since 2004 in Quebec and was cross-referenced with hospital pharmacy software to identify patients who had received at least one dose of G-CSF, such as filgrastim, while being exposed to clozapine. All data were collected retrospectively, using patients' medical files, from January to July 2019.

RESULTS

Using G-CSF, three out of eight patients could maintain clozapine despite neutropenia episodes that otherwise would have required treatment discontinuation. The only side effect reported was mild short-lived back pain, over a mean 3-year follow-up period. In all but one case, filgrastim was used on an "as-needed" basis at doses of 300 mcg administered subcutaneously.

CONCLUSION

These results suggest that the "as-needed" use of G-CSF is well-tolerated and may allow clozapine rechallenge in some well-selected patients, adding to the paucity of data regarding long-term safety and efficacy of this strategy. More research may help to better define potential candidates and optimal regimen of such practice.

Unravelling cases of clozapine-related Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) in patients reported otherwise: A systematic review

BACKGROUND

The drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is a drug-induced hypersensitivity reaction.

AIMS

Aim was to review reports of clozapine-related reactions fulfilling the registry of severe cutaneous adverse reaction (RegiSCAR) criteria for DRESS syndrome reported as such or otherwise, to provide a descriptive overview of demographic patterns, clinical manifestations, and DRESS course and investigate associations between demographic, DRESS parameters, and clinical outcomes.

METHODS

This review was conducted following preferred reporting items for systematic reviews and meta-analyses guidelines and registered with PROSPERO (registration number CRD42020156385). We searched PubMed/Embase/PsychInfo/Cochrane for reports of clozapine-related reactions meeting RegiSCAR criteria. Associations between RegiSCAR scores and time-to-recovery with demographic/clinical variables were assessed. Demographic/clinical characteristics of patients with versus without reported DRESS were compared using non-parametrical tests.

RESULTS

We identified 26 reports of 27 patients meeting RegiSCAR criteria. Males (n = 19, 70.4%) and patients with schizophrenia (n = 18, 66.7%) were mainly affected. Twelve patients (44.4%) received clozapine-monotherapy. DRESS symptoms manifested within a month after clozapine initiation (n = 24, 88.9%). Lungs and liver were the most common organs involved (n = 12, 44.4%; n = 11, 40.7%), with a mean time to recovery of 33.75 days. Clozapine rechallenge led to DRESS recurrence in four patients. Death rate was 7.4%. No associations were detected between RegiSCAR criteria or days to recovery with any demographic/clinical variables. No differences between patients with versus without reported DRESS were detected.

CONCLUSIONS

Clozapine-related DRESS may be rare, but also underreported. Clinicians need to be aware of it even in patients under clozapine-monotherapy or without skin rash.

Monitoring for myocarditis during treatment initiation with clozapine

OBJECTIVE

Clozapine use is associated with myocarditis. In this study, we investigated what clinical signs and symptoms, and/or laboratory test(s), alert clinicians to presumptive myocarditis (PrMy) most accurately and at the earliest time point. We also investigated the incidence of PrMy during the initial exposure to clozapine versus in patients restarted on clozapine after extended interruption of prior prolonged treatment.

METHODS

100 patients admitted to state psychiatric hospital started on clozapine were recruited into the study. 76 patients were treated with clozapine for the first time and 24 patients were restarts. Creatine kinase (CK), troponin I (TROP), eosinophil count (EOS), and C-reactive protein (CRP) were obtained at baseline and weeks 1, 2, 3, and 4. Descriptive statistics were calculated for demographic and clinical variables. Student's t test and chi-squared test were used to compare means and proportions between initial exposure and restart groups.

RESULTS

Clinical features and laboratory tests suggestive of PrMy were seen in 4 patients (5.3%) in initial exposure group and none in restart group. 3.5% of TROP levels were abnormal in initial exposure group and no abnormal levels were found in the restart group. 30% and 46% of CK, 23% and 39% of CRP, and 14% and 23% of EOS were abnormal in initial exposure group and restart groups, respectively.

CONCLUSIONS

PrMy was common (5.3%) during clozapine initiation. Prospective management through serial laboratory monitoring with weekly TROP levels was sensitive enough to allow for timely clozapine discontinuation.

Risk Factors, Incidence, and Outcomes of Neuroleptic Malignant Syndrome on Long-Acting Injectable vs Oral Antipsychotics in a Nationwide Schizophrenia Cohort

INTRODUCTION

Long-acting injectable antipsychotics (LAIs) are associated with multiple positive outcomes in psychosis, but it is unclear whether LAIs are associated with worse outcomes if neuroleptic malignant syndrome (NMS), a potentially lethal adverse effect, occurs.

METHODS

We used nationwide and nationally representative databases of healthcare encounters in Finland to study the incidence and outcome predictors of NMS in patients diagnosed with schizophrenia/schizoaffective disorder between January 01, 1972 and December 31, 2017. Using a nested case-control design, we also explored differences by antipsychotic formulation (LAI vs oral antipsychotic [OAP]) and class (first-generation antipsychotic [FGA] vs second-generation antipsychotic [SGA]).

RESULTS

One hundred seventy-two NMS cases and 1441 sex-, age-, and diagnosis-matched controls were included (age = 58.8 ± 13.1 years, males = 59.9%). Incidence of NMS was 1.99 (1.98-2.00) per 10 000 person-years. The likelihood of developing NMS did not differ by antipsychotic formulation (adjusted odds ratio [aOR]: 0.89, 95% confidence intervals [95% CI]: 0.59-1.33, for LAIs vs OAPs) or class (FGA-OAP vs SGA-OAP [aOR: 1.08, 95% CI: 0.66-1.76], FGA-LAI [aOR: 0.89, 95% CI: 0.52-1.53], SGA-LAI [aOR: 1.35, 95% CI: 0.58-3.12]). NMS risk factors included antipsychotic treatment change: increased number (odds ratios [OR]: 5.00, 95% CI: 2.56-9.73); decreased number/switch (OR: 2.43, 95% CI: 1.19-4.96); higher antipsychotic dose (>2DDDs-OR: 3.15, 95% CI: 1.61-6.18); co-treatment with anticholinergics (OR: 2.26, 95% CI: 1.57-3.24), lithium (OR: 2.16, 95% CI: 1.30-3.58), benzodiazepines (OR: 2.02, 95% CI: 1.44-3.58); and comorbid cardiovascular disease (OR: 1.73, 95% CI: 1.22-2.45). Within 30 days, 4.7% of cases with NMS died (15.1% within 1 year) without differences by antipsychotic formulation. NMS reoccurred in 5 of 119 subjects (4.2%), after a median = 795 (range = 77-839) days after rechallenge with antipsychotics.

CONCLUSION

NMS remains a potentially life-threatening risk, yet these results should further contribute to mitigate concerns about LAI safety regarding NMS onset or outcomes, including mortality.

Continuation of Treatment With Clozapine After an Episode of Neutropenia

BACKGROUND

Clozapine is the most effective in treatment-resistant schizophrenia. Neutropenia is an adverse effect of the drug requiring treatment discontinuation. This study related treatment continuation with little or no interruption after a neutropenia episode. The study contrasted from rechallenge studies after an extended treatment interruption.

METHODS

This retrospective chart audit examined 37 patients with an episode of neutropenia. It described characteristics of patients continuing treatment with minimal interruption.

FINDINGS

Thirty-one patients continued treatment after an initial treatment interruption for less than 3 days. A probable cause for neutropenia other than clozapine was identified in 14 patients. Twelve patients continued treatment with a change in the absolute neutrophil counts threshold to 1000/μL to determine treatment cessation. Most patients recovered from the index episode of neutropenia within 2 days. They also frequently presented with recurring benign episodes of low neutrophil cell counts during treatment than a comparative group.

IMPLICATIONS

The study recommends modifying clozapine treatment protocol absolute neutrophil count thresholds to less than 1000/μL to determine treatment cessation. Consideration of other probable causes for neutropenia, diurnal variations in cell counts, and laboratory errors reduced preemptive discontinuation of treatment. A risk-benefit approach supports continuing clozapine treatment after an episode of neutropenia.

Clozapine Is Better Tolerated in Younger Patients: Risk Factors for Discontinuation from a Nationwide Database in Japan

OBJECTIVE

The effectiveness of clozapine is clearly superior to other antipsychotics in the treatment of refractory schizophrenia. Clozapine leads to various side effects, and therefore many patients are forced to discontinue. In this study, we analyzed the registry database of all cases in Japan to identify risk factors for discontinuation of clozapine.

METHODS

The Clozaril patient monitoring service® (CPMS) database from July 31, 2009 to January 26, 2020 was acquired. We defined the following exclusion criteria: patients who had ever taken clozapine by a non-CPMS method, such as an individual import or clinical trial, patients who did not receive clozapine after being enrolled in CPMS, and patients with initial doses other than 12.5 mg (outside the current protocol). Therefore, all patients in this study are new users. Multivariate Cox regression analysis was used to investigate independent risk factors associated with time to discontinuation of clozapine.

RESULTS

We identified 8,263 patients as the study population. Clozapine discontinuation was significantly associated with age 40 and older [hazard ratio (HR)=1.66, p<0.001], intolerance to olanzapine (HR=1.31, p=0.018), previous treatment with clozapine (HR=1.30, p=0.001), and leukocyte counts <6,000/mm3 (HR=1.24, p<0.001). The Kaplan-Meier curves for clozapine discontinuation by age group revealed that older age at the time of clozapine introduction tended to have lower continuation rates.

CONCLUSION

Careful administration is important because patients with these factors have a high risk of discontinuation. In addition, the initiation of clozapine during the younger period was more effective and more tolerated.

Clozapine re-challenge and initiation following neutropenia: a review and case series of 14 patients in a high-secure forensic hospital

OBJECTIVE

Clozapine remains the most effective intervention for treatment resistant schizophrenia; however, its use is prohibited following neutropenias. We review neutrophil biology as applied to clozapine and describe the strategies to initiate clozapine following neutropenia used in a case series of 14 consecutive patients rechallenged in a United Kingdom (UK) high-secure psychiatric hospital. We examine outcomes including the use of seclusion and transfer.

METHODS

A case series of 14 male patients with treatment resistant schizophrenia treated with clozapine despite previous episodes of neutropenia between 2006 and 2015 is presented. Data were collected during 2015 and 2019. Using this routinely collected clinical data, we describe the patient characteristics, causes of neutropenia, the strategies used for rechallenging with clozapine and clinical outcomes.

RESULTS

Previous neutropenias were the result of benign ethnic neutropenia, clozapine, other medications and autoimmune-related. Our risk mitigation strategies included: granulocyte-colony stimulating factor (G-CSF), lithium and watch-and-wait. There were no serious adverse events; at follow up half of the patient's had improved sufficiently to transfer them to conditions of lesser security. There were dramatic reductions in the use of seclusion.

CONCLUSION

Even in this extreme group, clozapine can be safely and effectively re/initiated following neutropenias, resulting in marked benefits for patients. This requires careful planning based on an understanding of neutrophil biology and the aetiology of the specific episode of neutropenia.

Real-world effectiveness of olanzapine and risperidone in the treatment of schizophrenia in Brazil over a 16-year follow-up period; findings and implications

Introduction: Antipsychotics are widely prescribed for patients with schizophrenia. The Brazilian public health system provides these patients free of charge to patients and it is pertinent to evaluate their benefits.Objective: To evaluate the effectiveness of olanzapine and risperidone in the treatment of patients with schizophrenia in the real-world and assessing risk factors for their discontinuation through a national non-concurrent cohort with 16 years of follow-up.Methods: Three SUS administrative databases were integrated by deterministic-probabilistic linkage. After patients were matched (1:1) for psychiatric hospitalization, year of receiving the antipsychotic, sex, and age, considering either olanzapine or risperidone at study entry. Kaplan-Meier was used to estimate the cumulative probabilities of discontinuation of treatment and associated factors were identified. Sensitivity analyses were performed.Results: 3416 pairs of patients were included. Olanzapine had a longer time until discontinuation of treatment (p = 0.021), and risperidone had a higher risk of discontinuation (p = 0.021). Among patients persistent for at least 24 months, there was no statistically significant difference.Conclusion: Olanzapine demonstrated superior real-world effectiveness over risperidone, in terms of survival and psychiatric hospitalization. This superiority was not sustained in all analyses.

Successful Clozapine Re-Challenge After Suspected Clozapine-Induced Myocarditis

BACKGROUND Clozapine plays a unique role in the management of treatment-resistant schizophrenia (TRS). Clozapine re-challenge following an episode of myocarditis is controversial, with a very limited literature, although it may be crucial in the recovery of certain patients. To date and to the best of our knowledge, only 10 of 22 studied cases reported successful clozapine retrial after myocarditis. CASE REPORT We present the case of a 22-year-old Hispanic man with treatment-resistant schizophrenia and polysubstance use disorder (methamphetamine, cannabis, and alcohol) initiated on aggressive clozapine titration after lack of response to several other therapies. Approximately 16 days after clozapine trial, the patient developed cardiac function impairment, presenting with chest pain, notable elevation in several biomarkers (troponin: 0.72 ng/ml, ESR >100 mm/h, CRP: 20.8 mg/dl, and BNP: 999 ng/ml), and a depressed ejection fraction at 25%. Further assessments also showed positive hepatitis A serology. Following discontinuation of clozapine and providing supportive care, the patient's physical symptoms resolved. He had a relapse of psychotic symptoms, which were refractory to treatment with other antipsychotic agents. Subsequently, the patient underwent a second clozapine trial under close monitoring, with resolution of his psychosis. Repeated echocardiography demonstrated improved EF to 50%, transaminitis was resolved, repeat blood test results were normalized, and the patient was discharged while he was stabilized and asymptomatic. CONCLUSIONS This case adds to the previous case reports and suggests that clinicians may consider clozapine re-challenge following an episode of myocarditis based on clinical judgment, on a case-by-case basis, and under close monitoring. We highlight the need for development of clinical guidelines for clozapine re-challenge.

Persistence of Antipsychotic Use After Clozapine Discontinuation: A Real-World Study Across Antipsychotics

Although clozapine treatment is often discontinued due to limited efficacy or low tolerability, there is a lack of guidelines and evidence on treatment options after discontinuation of clozapine in patients with schizophrenia. Persistence has proven to be an adequate indicator for treatment effectiveness in patients with schizophrenia. The aim of this study was, therefore, to compare persistence of antipsychotic use between antipsychotic treatment options in patients after stopping clozapine treatment. Registry data from a prescription database representative of the Dutch population (1996-2017) was collected to investigate persistence in patients with schizophrenia who had been using clozapine for ≥ 90 days. Persistence with antipsychotics after clozapine discontinuation was analyzed using Cox-proportional hazard regression models. Our study population consisted of 321 participants, of whom 138 re-initiated clozapine and 183 started some other antipsychotic in the year after clozapine discontinuation (N = 518 antipsychotic use periods, N = 9,178 months). Second-generation antipsychotics (SGAs) as a group were associated with better persistence compared to first-generation antipsychotics (adjusted hazard ratio (aHR), 0.73; 95% confidence interval (CI) 0.57-0.93; P = 0.011). Compared with other antipsychotics, the following oral monotherapy antipsychotics were associated with significantly better persistence: restarting clozapine (aHR 0.48; 95% CI 0.32-0.71; P < 0.001) and switching to risperidone (aHR 0.52; 95% CI 0.32-0.84; P = 0.008) or olanzapine (aHR 0.55; 95% CI 0.35-0.87; P = 0.010). Sensitivity analyses confirmed the results. In conclusion, oral SGAs are associated with better persistence than alternative antipsychotic treatment options in patients discontinuing clozapine for undefined reasons. Especially clozapine (except in those with previous serious adverse reactions to clozapine), olanzapine and risperidone should be considered as oral monotherapy for these patients.

Clozapine in the treatment of refractory schizophrenia: a practical guide for healthcare professionals

BACKGROUND

Clozapine remains the only medication licensed for treating refractory schizophrenia. However, it remains underutilized in part due to concerns regarding adverse events.

SOURCES OF DATA

Published literature.

AREAS OF AGREEMENT

Common adverse events during clozapine treatment include sedation, hypersalivation, postural hypotension, dysphagia, gastrointestinal hypomotility, weight gain, diabetes mellitus and dyslipidaemia. Rare but serious events include agranulocytosis, cardiomyopathy, myocarditis, pneumonia, paralytic ileus and seizure.

AREAS OF CONTROVERSY

It remains unclear how best to minimize clozapine-induced morbidity/mortality (i) during dose titration, (ii) from hypersalivation and (iii) from gastrointestinal hypomotility. It is also unclear how clozapine pharmacokinetics are affected by (i) gastrointestinal hypomotility, (ii) systemic infection and (iii) passive exposure to cigarette smoke. Whether monthly haematological monitoring needs to continue after 12 months of uninterrupted therapy is also a subject of debate.

GROWING POINTS

There is a need for better management of serious clozapine-related adverse events in addition to agranulocytosis. There is also a need for better education of patients and carers, general practitioners, A&E and ITU staff and others of the problems posed in using clozapine safely.

AREAS TIMELY FOR DEVELOPING RESEARCH

There is a need for more research on assessing clozapine dosage (i) as patients get older, (ii) with respect to exposure to cigarette smoke and (iii) optimizing response if adverse events or other factors limit dosage.

In the aftermath of clozapine discontinuation: comparative effectiveness and safety of antipsychotics in patients with schizophrenia who discontinue clozapine

BACKGROUND

Although clozapine is often discontinued, there is a paucity of guidelines and evidence on treatment options after clozapine discontinuation. Moreover, it is currently unknown whether reinstating clozapine in patients formerly using clozapine should be avoided.

AIMS

To compare the real-world effectiveness of antipsychotics after clozapine cessation.

METHOD

From Finnish registry data (1995-2017), we identified 2250 patients with schizophrenia who had been using clozapine for ≥1 year before treatment cessation. The primary analysis consisted of adjusted within-individual analyses of psychiatric ward readmission owing to psychosis and treatment failure. Secondary analyses concerned between-individual mortality differences.

RESULTS

Compared with no use of antipsychotics, risk of psychiatric ward readmission was lowest for reinitiation of clozapine (adjusted hazard ratio (aHR) 0.49; 95% CI 0.40-0.61; P < 0.0001), oral olanzapine (aHR 0.58; 95% CI 0.48-0.71; P < 0.0001) and antipsychotic polypharmacy (aHR 0.62; 95% CI 0.53-0.72; P < 0.0001). Risk of treatment failure was lowest for aripiprazole long acting injectable (aHR 0.42; 95% CI 0.27-0.65; P < 0.0001), reinitiation of clozapine (aHR 0.49; 95% CI 0.43-0.57; P < 0.0001) and oral olanzapine (aHR 0.69; 95% CI 0.61-0.77; P < 0.0001). Mortality risk was lowest for reinitiation of clozapine (aHR 0.18; 95% CI 0.09-0.36; P < 0.0001) and oral olanzapine (aHR 0.26; 95% CI 0.17-0.40; P < 0.0001).

CONCLUSIONS

Clozapine and olanzapine are the most effective and safest treatment options in those discontinuing clozapine for undefined reasons. Clozapine should therefore be reconsidered in patients with schizophrenia who previously discontinued this compound.

Protocol for Clozapine Rechallenge in a Case of Clozapine-Induced Myocarditis

OBJECTIVE

Protocol for clozapine rechallenge in patients with a history of clozapine-induced myocarditis.

METHOD

Clozapine-related cardiovascular adverse effects including myocarditis and cardiomyopathy have limited its widespread use in treatment-resistant schizophrenia. Here, we present a case of clozapine-induced myocarditis and successful cautious rechallenge. Ms. AA, a young female patient with severe psychosis developed myocarditis during her initial clozapine titration phase, which was thus discontinued. Subsequent response to other medications was poor, and she remained significantly disabled. We reviewed blood-based biomarkers identified during the emergence of her index episode of myocarditis and developed a successful clozapine rechallenge protocol, based on careful monitoring of changes in these indices and a very slow clozapine re-titration.

RESULTS AND CONCLUSIONS

This protocol may have utility in the management of patients with a history of clozapine-induced myocarditis.

Clozapine rechallenge and initiation despite neutropenia- a practical, step-by-step guide

Clozapine remains the only drug treatment likely to benefit patients with treatment resistant schizophrenia. Its use is complicated by an increased risk of neutropenia and so there are stringent monitoring requirements and restrictions in those with previous neutropenia from any cause or from clozapine in particular. Despite these difficulties clozapine may yet be used following neutropenia, albeit with caution. Having had involvement with 14 cases of clozapine use in these circumstances we set out our approach to the assessment of risks and benefits, risk mitigation and monitoring with a practical guide.

Successful clozapine rechallenge following recurrent clozapine-associated pancreatitis: a case report

Background

Acute pancreatitis is a rare but recognised complication of clozapine leading to termination of treatment.

Case presentation

We present the case of a 39-year-old man with treatment-resistant schizoaffective disorder and a history of recurrent acute pancreatitis attributed to clozapine. After 15 years of unremitting symptoms with disruptive and aggressive behaviour, he was admitted for a clozapine rechallenge. Despite experiencing two further episodes of acute pancreatitis during clozapine treatment that led to its temporary withdrawal, clozapine was successfully re-established under gastroenterology consultation with close monitoring which resulted in progressively marked improvement of his mental state.

Conclusions

This case demonstrates that patients who develop pancreatitis during clozapine treatment may be cautiously rechallenged with specialist gastroenterology support.

How and when to use clozapine

OBJECTIVE

Clozapine is the only approved strategy for treatment-resistant schizophrenia, although it is highly underutilized. We aim to generate practical and actionable evidence-based recommendations for the use of this drug considering prescription barriers.

METHOD

Narrative review.

RESULTS

A consistent body of evidence supports the efficacy of clozapine reducing morbidity and mortality in schizophrenia. The main obstacles to its use are the lack of experience by prescribers and perceived treatment burden. Systematic screening of eligibility, utilization of available resources for consultation, developing a professional network with other stakeholders, as well as optimizing how clozapine is presented to patients is discussed. Furthermore, specific evidence-based recommendations for initiation, maintenance, and safety monitoring with clozapine are provided.

CONCLUSION

Clozapine prescription is one of the areas in psychiatry with the greatest mismatch between efficacy and utilization in clinical practice. Although multiple barriers to the use of clozapine exist, some of these may be overcome by updates of routine clinical practice.

Clozapine-Related Myocarditis and Rechallenge: A Case Series and Clinical Review

PURPOSE/BACKGROUND

That clozapine is the only agent with an indication for treatment-resistant schizophrenia presents real challenges if clozapine-related myocarditis (CIM) occurs. Clinicians have chosen to rechallenge with a second trial of clozapine in the face of CIM. However, there is very limited literature of this topic.

METHODS/PROCEDURES

Three cases who underwent clozapine rechallenge after CIM are reviewed and discussed in the context of existing literature and current recommendations.

FINDINGS/RESULTS

We present 3 young male patients with schizophrenia and schizoaffective disorder who developed CIM during a first clozapine trial, stopped treatment, and subsequently underwent a second clozapine trial. In all cases, the rechallenge was discontinued owing to suspected CIM. A review of the literature includes reports of both successful and unsuccessful clozapine rechallenges after CIM and suggests certain risk factors. Clozapine rechallenge after CIM may be undertaken, as now occurs on occasion with agranulocytosis, although rates of success may be lower. Any such undertaking calls for education, careful monitoring, cautious titration, and a multidisciplinary approach. The balance of risk versus benefits must be considered, and strategies may include a drug holiday, more frequent monitoring upon reinitiation, and slower titration.

IMPLICATIONS/CONCLUSIONS

Pressure to undertake a rechallenge reflects clozapine's unique role in treatment-resistant schizophrenia and absence of other comparable options. However, it is not without risk, and more research is needed to understand those at increased risk, as well as established strategies that diminish this.

A Validated Method for the Simultaneous Determination of Quetiapine, Clozapine and Mirtazapine in Postmortem Blood and Tissue Samples

Psychotropic drugs are regularly present in cases of sudden, unexpected death. Such drugs also tend to express significant postmortem redistribution. To facilitate further investigation of this phenomenon, reliable quantitative methods applicable to multiple biological matrices are needed. We present a validated ultra-performance liquid chromatography–tandem mass spectrometry method for the simultaneous quantification of quetiapine, clozapine and mirtazapine in postmortem whole blood, skeletal muscle, brain tissue and liver tissue using high-performance liquid chromatography–tandem mass spectrometry. Sample preparation was performed using liquid–liquid extraction. The validated ranges were 3.8–1534, 16–1960 and 13–1060 μg/L for quetiapine, clozapine and mirtazapine, respectively. Within-run and between-run accuracy (87.4–122%) and precision (CV 1.5–8.9%), matrix effects (95–101%) and recovery (35.7–92%) were validated at two concentration levels; 5.8 and 1227 μg/L for quetiapine, 25 and 1568 μg/L for clozapine and 20 and 849 μg/L for mirtazapine. Stability in a 10°C environment was assessed for treated samples of brain, liver and muscle tissue, showing deviations in analyte concentrations ranging from −8% to 9% after 3 days. The analyte concentrations in treated samples of whole blood stored at 4°C deviated by &lt;5% after 5 days. The method was applied in three forensic autopsy cases implicating quetiapine, clozapine and mirtazapine, respectively, in supratherapeutic concentrations.

A comparative study of detection of myocarditis induced by clozapine: With and without cardiac monitoring

The aim of this study was to investigate and compare the incidence of suspected or definite cases of clozapine induced myocarditis (SDM) and clinical factors which could influence its onset in two different time periods, defined by pre- and post-cardiac monitoring at an inpatient setting, during the initiation phase of clozapine treatment. Hospital records of patients started on clozapine in the inpatient unit between 2011 and 2018 were investigated. Eight in 38 patients (11.3%) were classified as SDM after the initiation of the monitoring protocol, whereas only 1 in 33 patients (1.4%) was classified as SDM, before. Monitored and non-monitored patient groups were similar with regard to demographic and clinical variables. Diagnosis of schizoaffective disorder and use of concominant lithium, valproic acid and atypical antipsychotics were higher in patients with SDM, while clozapine dose titration was similar compared to the rest of the patients. Cardiac monitoring seems to be the main factor leading to the increase in the detection of clozapine induced myocarditis (CIM). If not monitored, the outcome of CIM can be fatal without any warning signs and symptoms. Concominant use of mood stabilizers including valproic acid and lithium, are important risk factors for the development of CIM.

Pericardial Effusion: Rare Adverse Effect of Clozapine

Clozapine is a dibenzodiazepine antipsychotic used for resistant schizophrenia, which is known to be associated with side effects such as agranulocytosis, seizures, weight gain, and less commonly myocarditis/ cardiomyopathy. We present a case of a 20-year-old female who presented with chest pain, shortness of breath, and cough. She was later found to have clozapine-induced pericardial effusion that resolved after discontinuation of clozapine therapy. Our case discloses the importance to consider clozapine in the differential diagnosis of pericardial effusion as discontinuation of the drug leads to resolution of effusion, with no need for further treatment.