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

A 12-month audit of clozapine associated myocarditis in a South Australian Local Health Network: The importance of screening and personalised titration

Clozapine is effective in up to 50 % of patients resistant to other antipsychotics. Its use is restricted to third-line due to adverse effects which include myocarditis. Australia reports the highest incidence of clozapine-associated myocarditis (CAM) in the context of pharmacovigilance and relatively rapid titration. An audit of patients commenced on clozapine within the Central Adelaide Local Health Network (CALHN) between 2012 and 2015 found an incidence of 8.6 %. We present here a case series from a follow up audit considering titration relevant risk factors for CAM. We reviewed anecdotal cases and data from all hospital-based commencements of clozapine across CALHN for the period July 2021 to June 2022 using pharmacy and medical record databases. We identified 5 cases of CAM and all had risk factors impacting on clozapine metabolism, including rapid titration, elevated baseline CRP, Asian ethnicity and concomitant treatment with inhibitors of clozapine metabolism. While personalisation of clozapine treatment needs further investigation in prospective trials, slower titration to lower targets for risk groups may not impact on hospital length of stay and has the potential to significantly reduce the burden of adverse events. Australian manufacturer approved titration rates exceed those recommended for personalised dosing and may not be safe for patients with risk factors. Early clozapine levels at week two could identify slow metabolisers for dose adjustment. Closer ties between psychiatrists and cardiologists are critical for the development of protocols for safely maintaining clozapine treatment during low level cardiac inflammation and to support safe rechallenge.

Overcoming clozapine's adverse events: a narrative review of systematic reviews and meta-analyses

INTRODUCTION

Clozapine is the gold standard treatment for treatment resistant schizophrenia, however adverse events remain a clinical challenge.

AREAS COVERED

This review presents a narrative synthesis of systematic reviews and meta-analyses that have reported the onset, incidence, prevalence, and management of clozapine's adverse events. We conducted a systematic literature search using PubMed, Embase, PsycINFO, OvidMEDLINE, CINAHL, and the Cochrane Database of Systematic Reviews from inception to April 2024.

EXPERT OPINION

Effective management of clozapine's adverse events necessitates multi-faceted, individualized, and shared-decision strategies. Despite a lack of high-quality systematic evidence, expert inter-disciplinary solutions are provided to help address a critical need for clinical guidance. This 35-year update offers an evidence-based framework to assist clinicians, patients, and caregivers navigate the adverse events associated with clozapine therapy.

A systematic review of clozapine-associated inflammation and related monitoring

Clozapine is an effective antipsychotic medication used for treatment-resistant schizophrenia. However, it is underutilized due to rigorous hematologic monitoring requirements and many adverse drug reactions. Publications have highlighted the occurrence of inflammatory reactions, some life-threatening, particularly during the early stages of clozapine treatment. Although guidelines have suggested monitoring for inflammatory processes during clozapine initiation, screening in clinical practice is not universal. This systematic review aimed to investigate the relationship between clozapine and inflammation and assess the importance of monitoring for inflammatory reactions. A comprehensive literature search yielded 6915 unique publication records after removal of duplicates. After a rigorous screening process, 75 publications were included in the review, which focused on three main aspects: (i) the impact of clozapine on inflammatory markers, (ii) monitoring cardiac and other organ function during clozapine-associated inflammatory processes, and (iii) monitoring non-specific signs and symptoms of inflammation. Elevated levels of C-reactive protein (CRP) and several proinflammatory cytokines have been observed in association with clozapine treatment. However, the practicality of measuring specific markers in clinical practice remains uncertain. Current evidence supports monitoring CRP levels during the first 4-8 weeks of treatment, especially to facilitate myocarditis screening. Further research is needed to establish clinically relevant CRP thresholds for intervention. The implementation of monitoring protocols during the early phase of clozapine treatment may mitigate adverse reactions and allow for continued use of clozapine. Future studies should also explore the association between clozapine-associated inflammation and pneumonia, as well as investigate the impact of inflammation on clozapine metabolism to predict the need for dose adjustment. These endeavors may facilitate the development and implementation of evidence-based guidelines for the monitoring of clozapine-associated inflammation.

[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.

Clozapine Optimization: A Delphi Consensus Guideline From the Treatment Response and Resistance in Psychosis Working Group

BACKGROUND AND HYPOTHESIS

There is limited evidence to guide the approaches to clozapine treatment. Accordingly, an international initiative was undertaken with the aim of developing consensus recommendations for the optimization of clozapine monotherapy.

STUDY DESIGN

We conducted an online Delphi survey among members of the Treatment Response and Resistance in Psychosis (TRRIP) working group comprising experts from twenty-nine countries. The threshold criterion for a consensus recommendation was ≥ 75% agreement ("agree" and "strongly agree" responses) on a question. Agreement of ≥ 50% but < 75% in a second or third Delphi round was deemed to provide guidance.

STUDY RESULTS

Forty-nine (first round), 32 (second round), and 48 (third round) of the 91 current TRRIP members participated. Expert recommendations at ≥ 75% comprised second-line treatment with clozapine in cases of persistent positive symptoms with co-occurring extrapyramidal symptoms, tardive dyskinesia, or suicidality/aggression. There was considerable disagreement on myocarditis screening parameters. The management of somatic and neuropsychiatric adverse drug reactions warrants further research for more evidence-based recommendations. Rechallenge with clozapine was recommended for eosinophilia, sinus tachycardia and fever and guidance (agreement ≥ 50%) was reached for pneumonia and thrombocytopenia.

CONCLUSIONS

Given the limited evidence available, this consensus-based series of recommendations and guidance statements supports clinical decision-making to optimize clozapine monotherapy and provides guidance for future research in treatment-resistant schizophrenia.

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.

Clozapine-induced myocarditis in children and adolescents: a pharmacovigilance study using VigiBase and a systematic literature review

INTRODUCTION

Clozapine-induced myocarditis in children (age ≤18 yo) was studied from a PubMed search (18 July 2022) (9 cases) and from the World Health Organization's pharmacovigilance database, called Vigibase, of adverse drug reaction (ADR) reports (72 non-duplicated cases). VigiBase uses a logarithmic measure of disproportionality called the information component (IC). A logistic regression model of presence/absence (40/32) of seriousness in VigiBase was developed.

AREAS COVERED

VigiBase provided a significant myocarditis IC = 4.2 with an IC₀₂₅ = 3.8; only 4 clozapine-induced myocarditis cases were expected, while 72 were observed. The PubMed search identified 9 cases, while VigiBase identified 72 cases (of which 67 did not overlap with published cases). These 76 combined cases included 35 doubtful (most with missing information on the day of diagnosis), 19 possible and 22 probable, according to the ADR scale. After adjusting for confounders, quetiapine increased the risk of seriousness with an odds ratio (OR) of 17.6 (95% confidence interval CI, 1.56 to 198.6), while Australian origin decreased it with an OR = 0.13 (CI, 0.04 to 0.47).

EXPERT OPINION

These 41 cases of at least possible clozapine-induced myocarditis indicated that this ADR can definitively occur in children, particularly in the first 30 days of up-titration. Children's and adult cases appeared similar.

Mapping the Knowledge of Antipsychotics-Induced Sudden Cardiac Death: A Scientometric Analysis in CiteSpace and VOSviewer

The drugs on the market for schizophrenia are first-generation and second-generation antipsychotics. Some of the first-generation drugs have more side effects than the other drugs, so they are gradually no longer being applied clinically. Years of research have shown that the risk of sudden cardiac death in psychotic patients is associated with drug use, and antipsychotic drugs have certain cardiotoxicity and can induce arrhythmias. The mechanism of antipsychotic-induced sudden cardiac death is complicated. Highly cited papers are among the most commonly used indicators for measuring scientific excellence. This article presents a high-level analysis of highly cited papers using Web of Science core collection databases, scientometrics methods, and thematic clusters. Temporal dynamics of focus topics are identified using a collaborative network (author, institution, thematic clusters, and temporal dynamics of focus topics are identified), keyword co-occurrence analysis, co-citation clustering, and keyword evolution. The primary purpose of this study is to discuss the visual results, summarize the research progress, and predict the future research trends by bibliometric methods of CiteSpace and VOSviewer. This study showed that a research hotspot is that the mechanisms of cardiotoxicity, the safety monitoring, and the assessment of the risk-benefit during clinical use of some newer antipsychotics, clozapine and olanzapine. We discussed relevant key articles briefly and provided ideas for future research directions for more researchers to conduct related research.