Clozapine and sudden death

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.

Safety profile of clozapine: Analysis using national registry data in Japan

Clozapine is the only effective antipsychotic drug used for the treatment of treatment-resistant schizophrenia. Although it has been shown that the frequency of clozapine use is very low in Japan, our previous study revealed that the number of clozapine prescriptions has been increasing in recent years, and that risk factors leading to discontinuation of clozapine were also identified as age ≥40 years, poor tolerability to olanzapine, previous treatment with clozapine, and white blood cell count <6000/mm³. The main cause for discontinuation of clozapine is the occurrence of a wide range of adverse events, including neutropenia/leukopenia and fatal cardiac disorders. In this study, we analyzed the physical details and backgrounds of patients with adverse events that led to clozapine discontinuation using a national registry database of more than 8000 Japanese patients. The physical adverse events that led to discontinuation of clozapine were neutropenia/leukopenia, glucose intolerance, cardiac disorders, gastrointestinal disorders, neuroleptic malignant syndrome, pleurisy, pulmonary embolism, sedation/somnolence, and seizures. Neutropenia/leukopenia had the highest incidence (5.0%). Neutropenia/leukopenia and cardiac disorders tended to occur early in the treatment period, indicating the need for careful monitoring for these adverse events in the early stages of clozapine treatment. Gastrointestinal disorders occurred over a long period of time, suggesting the need for careful observation during the maintenance period. The data obtained in our study will lead to the optimal and safe use of clozapine treatment.

Understanding and managing cardiac side-effects of second-generation antipsychotics in the treatment of schizophrenia

Second-generation antipsychotic medications (SGAs) have advanced the treatment of schizophrenia over the past 30 years. However, a number of potentially life-threatening cardiac side-effects associated with these treatments concern and can discourage prescribers from administering these evidence-based treatments. This review provides a practical, psychiatrist-oriented understanding of the relative frequencies, mechanisms, investigations and treatments associated with these cardiac toxicities. We aim to highlight that these are relatively rare complications of an effective class of drug and to promote the advantages of early involvement of cardiologists in the psychiatric multidisciplinary team to guide the investigation and management of these conditions.

LEARNING OBJECTIVES

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Clozapine-induced cardiomyopathy and myocarditis monitoring: A systematic review

The use of clozapine requires monitoring the absolute neutrophil count because of the risk of agranulocytosis, but other potentially fatal adverse events associated with clozapine (specifically, myocarditis and cardiomyopathy) do not have mandatory procedures. We performed a systematic review of English-language articles to synthesize an evidence-based approach for myocarditis and cardiomyopathy monitoring. Articles published from January 1988 through February 2017 were identified through a search of Ovid MEDLINE, Ovid Embase, Ovid Cochrane Database of Systematic Reviews, Web of Science, Scopus, and Google Scholar. Selected articles were required to relate to myocarditis or cardiomyopathy in humans from exposure to clozapine. A total of 144 articles were included. Recommendations varied widely. Some authors recommended baseline laboratory monitoring, with or without follow-up testing, for C-reactive protein, creatine kinase MB, and troponin. Electrocardiography was commonly recommended, and echocardiography was less commonly recommended. The expense of monitoring was a consideration. A unanimous recommendation was to stop the use of clozapine and seek a cardiovascular consultation if myocarditis or cardiomyopathy is suspected. Although there is general agreement on which tests to perform for confirming myocarditis and cardiomyopathy, preemptive screening for these clozapine-induced conditions is controversial, and cost and barriers for the use of clozapine are concerns. For asymptomatic patients receiving clozapine, testing could include baseline electrocardiography, echocardiography as part of a cardiac consultation if patients have cardiac disease or risk factors, and monitoring of C-reactive protein and troponin as indicated.

Therapeutic Options in the Treatment of Clozapine-Induced Adverse Effects

Objective:

To review the therapeutic options in the management of clozapine-induced adverse effects.

Data Sources:

A MEDLINE search (from 1966 to present) was conducted, and English-language studies and review articles were retrieved to review the adverse effects of clozapine and their management.

Study Selection and Data Extraction:

All studies evaluating clozapine's adverse effects, such as agranulocytosis, seizures, neuroleptic malignant syndrome, hypersalivation, weight gain, sedation, fatigue, orthostatic hypotension, eosinophilia, delirium, new-onset diabetes, constipation, nausea, tachycardia, myocarditis, and pancreatitis, and their management were included.

Data Synthesis:

Clozapine, an atypical antipsychotic that has been proven effective and comparable, as well as superior, to conventional antipsychotics in treatment-resistant schizophrenia, is also being used in the treatment of a wide variety of other psychiatric conditions, including suicidal ideation, tardive dyskinesia, and affective disorders such as depression, bipolar disorders, and schizoaffective disorder. Although clozapine exhibits a markedly low incidence of extrapyramidal symptoms compared with similar medications, it has other adverse effects, some of which are potentially life threatening, requiring careful monitoring. The adverse effects of clozapine range from benign drooling, weight gain, nausea, and constipation, to life-threatening agranulocytosis, seizures, and neuroleptic malignant syndrome (NMS). Mandatory periodic white blood cell monitoring has resulted in dramatic reduction in mortality due to clozapine-induced agranulocytosis, promoting high adherence by patients. Prompt diagnosis and treatment of adverse effects of clozapine has also been effective in reducing complications, including mortality due to other serious adverse effects such as NMS and seizure. Other adverse effects are comparatively benign and can be managed effectively.

Conclusions:

Clozapine has a wide variety of adverse effects, some of which are potentially life threatening. Clinicians should be aware of possible severe complications and emergency management. Differentiating between minor and major adverse effects and initiating appropriate intervention is essential for a positive therapeutic outcome when prescribing clozapine.

Lessons Learned and Questions Raised by an Atypical Case of Clozapine-Induced Myocarditis

A Caucasian male in his early twenties suffering from treatment resistant schizophrenia was started on clozapine. After three days he developed tachycardia, a common side effect of clozapine induction. He had one temperature spike (38.9°C) on day ten after induction but remained clinically well. An ECG and blood tests were normal. Due to persistent tachycardia and an episode of collapse whilst seated on day 12, he was admitted to hospital for further investigation. A diagnosis of myocarditis was confirmed as a result of elevated cardiac enzyme levels and an echocardiogram. Following withdrawal of clozapine, supportive management, and initiation of cardiac medication, the patient made a successful recovery. He will be followed up with the cardiology team to ensure that his heart function returns to normal. Given the incidence of clozapine-induced myocarditis, the associated mortality risk, and diagnostic difficulties, this case raises questions about whether a formal system for identifying myocarditis should be adopted.

Inflammatory response to clozapine in the absence of myocarditis: case report

SUMMARY

A case is presented of a 25-year-old man with treatment-resistant paranoid schizophrenia whose only previous trial of clozapine had been stopped following a suspected clozapine-induced myocarditis. Due to the failure of his psychosis to respond to a number of antipsychotic treatments and augmentation strategies, clozapine was restarted on admission. His rechallenge was marked by intermittent pyrexia, tachycardia and elevated C-reactive protein (CRP), but eosinophilia was absent. Clozapine was started and then stopped twice following extensive investigation and with specialist cardiology consultation. Physical symptoms and CRP elevation resolved shortly after clozapine cessation. We believe this constituted an idiosyncratic systemic inflammatory response to clozapine treatment.

DECLARATION OF INTEREST

None.

COPYRIGHT AND USAGE

© The Royal College of Psychiatrists 2016. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) licence.

Making clozapine safer: current perspectives on improving its tolerability

ABSTRACT: 

Clozapine is the gold standard treatment for refractory schizophrenia and its benefits are supported by an evidence base. Yet, it remains largely underused in clinical practice. This is because of low acceptability from patients and reluctance in initiating, and delays in prescribing by clinicians. A major deterrent is often the common adverse reactions, which clinicians are apt to disregard, focusing instead on the severe but rare complications of clozapine, such as agranulocytosis. We will review recent evidence on increasing the prescription of clozapine, focusing particularly on improving the safety and tolerability of the drug, by effective management of its adverse effects. The adverse effects considered in our review include sedation, seizures, myoclonus, hypersalivation, nausea, constipation, hypotension, hypertension, tachycardia, myocarditis, cardiomyopathy, weight gain, diabetes, dyslipidemia, neutropenia, agranulocytosis, fever, nocturnal enuresis and obsessive–compulsive symptoms. We will also discuss strategies to enable successful clozapine rechallenge after severe cardiac and hematological adverse reactions, thus aiming to offer patients their best chance at recovery.

Evaluating the association between clozapine and venous thromboembolism

PURPOSE

The possible association between clozapine and venous thromboembolism (VTE) is discussed.

SUMMARY

Twenty-two cases of VTE associated with clozapine have been published. The average patient age at the time of occurrence was 38 years in the reported cases. Of the published cases with a known outcome, the mortality rate of a clotting complication while on clozapine was approximately 44%. The manufacturer of clozapine has calculated a mortality rate from pulmonary embolism to be one death per 3450 person years of use, approximately 28 times higher than the rate in the general population. The possible mechanism for the association between clozapine and VTE is probably multifactorial. A VTE usually occurs when one of three factors is present: damage to the vessel wall, static blood flow, or coagulation abnormalities. Clozapine, as well as other antipsychotics, has not been shown to cause direct damage to the vasculature in humans. However, static blood flow may be influenced by sedation and the sedentary lifestyle commonly associated with psychiatric disorders, their treatment, or both. Clozapine is associated with significant sedation and an average weight gain of 7-11 kg. There is also increasing evidence that clozapine and other antipsychotics may cause a variety of different coagulation abnormalities. Clozapine has been found to increase platelet adhesion as well as aggregation. Avoidance of risk factors, such as weight gain and sedentary lifestyle, may alleviate some of the risk of clozapine-induced VTE.

CONCLUSION

Available data indicate an association between clozapine and VTE; however, it is unknown whether the increased risk of VTE in patients receiving clozapine is because of prothrombotic effects of the drug. Risk of VTE versus the benefits of therapy should be considered when initiating clozapine therapy.

Cardiac side effects of psychiatric drugs

This review describes the common effects of psychotropic drugs on the cardiovascular system and offers guidance for practical management. Selected reports from the literature describing common side effects associated with psychotropic drugs are reviewed, and suggestions for further reading are given throughout the text. Orthostatic hypotension is the most common adverse autonomic side effect of antipsychotic drugs. Among the atypical antipsychotics the risk of orthostatic hypotension is highest with clozapine and among the conventional drugs the risk is highest with low potency agents. Rarely, orthostatic hypotension may result in neurocardiogenic syncope. QTc prolongation can occur with all antipsychotics but an increased risk is seen with pimozide, thioridazine, sertindole and zotepine. QTc prolongation is a marker of arrhythmic risk. Torsade de pointe, a specific arrhythmia, may lead to syncope, dizziness or ventricular fibrillation and sudden death. Heart muscle disease presents most commonly in the elderly as chronic heart failure, but myocarditis and cardiomyopathy, although relatively rare, are devastating, but potentially reversible complications of psychotropic drug therapy have been particularly linked to clozapine treatment. Patients with severe mental illness (SMI) are a 'high risk' population with regard to cardiovascular morbidity and mortality. It is probable that many patients accumulate an excess of 'traditional' risk factors for the development of cardiovascular disease, but other mechanisms including psychotropic drugs may also be influential in increasing risk in this vulnerable group. These risks need to be seen in the context of the undoubted therapeutic efficacy of the psychotropic armamentarium and the relief that these drugs bring to those suffering from mental disorder.

Adverse effects of atypical antipsychotics : differential risk and clinical implications

Antipsychotic drugs can be of great benefit in a range of psychiatric disorders, including schizophrenia and bipolar disorder, but all are associated with a wide range of potential adverse effects. These can impair quality of life, cause stigma, lead to poor adherence with medication, cause physical morbidity and, in extreme cases, be fatal. A comprehensive overview of tolerability requires a review of all available data, including randomised controlled trials (RCTs), observational studies and postmarketing surveillance studies. Assessing the relative tolerability of atypical antipsychotics is hampered by the paucity of RCTs that compare these drugs head-to-head, and limited and inconsistent reporting of adverse effect data that makes cross-study comparisons difficult. Despite methodological problems in assessment and interpretation of tolerability data, important differences exist between the atypical antipsychotics in the relative risk of acute extrapyramidal symptoms (highest risk: higher doses of risperidone), hyperglycaemia and dyslipidaemia (highest risk: clozapine and olanzapine), hyperprolactinaemia (highest risk: amisulpride and risperidone), prolongation of heart rate-corrected QT interval (QTc) [highest risk: ziprasidone and sertindole] and weight gain (highest risk: clozapine and olanzapine). Sedation, antimuscarinic symptoms, postural hypotension, agranulocytosis and seizures are more common with clozapine than with other atypical antipsychotics. The variation in their tolerability suggests that it is misleading to regard the atypical antipsychotics as a uniform drug class, and also means that the term 'atypical antipsychotic' has only limited usefulness. Differences between the atypical agents in terms of efficacy and pharmacodynamic profiles also support this view. As tolerability differs between specific conventional and atypical drugs, we conclude that broad statements comparing the relative risk of specific adverse effects between 'atypical' and 'conventional' antipsychotics are largely meaningless; rather, comparisons should be made between specific atypical and specific conventional drugs. Adverse effects are usually dose dependent and can be influenced by patient characteristics, including age and gender. These confounding factors should be considered in clinical practice and in the interpretation of research data. Selection of an antipsychotic should be on an individual patient basis. Patients should be involved in prescribing decisions and this should involve discussion about adverse effects.

World Federation of Societies of Biological Psychiatry (WFSBP) guidelines for biological treatment of schizophrenia, Part 1: acute treatment of schizophrenia

These guide lines for the biological treatment of schizophrenia were developed by an international Task Force of the World Federation of Societies of Biological Psychiatry (WFSBO). The goal during the development of these guidelines was to review systematically all available evidence pertaining to the treatment of schizophrenia, and to reach a consensus on a series of practice recommendations that are clinically and scientifically meaningful based on the available evidence. These guidelines are intended for use by all physicians seeing and treating people with schizophrenia. The data used for developing these guidelines have been extracted primarily from various national treatment guidelines and panels for schizophrenia, as well as from meta-analyses, reviews and randomised clinical trials on the efficacy of pharmacological and other biological treatment interventions identified by a search of the MEDLINE database and Cochrane Library. The identified literature was evaluated with respect to the strength of evidence for its efficacy and then categorised into four levels of evidence (A-D). This first part of the guidelines covers disease definition, classification, epidemiology and course of schizophrenia, as well as the management of the acute phase treatment. These guidelines are primarily concerned with the biological treatment (including antipsychotic medication, other pharmacological treatment options, electroconvulsive therapy, adjunctive and novel therapeutic strategies) of adults suffering from schizophrenia.

Myocarditis and cardiomyopathy linked with clozapine treatment

Clozapine is associated with a risk of myocarditis and cardiomyopathy. The exact mechanisms still remains unclear although there have been a range of proposals ranging from hypersensitivity reactions, toxic effects of the drug to vitamin deficiency. We present three cases where there were minor deviations of heart function or structure prior to the onset of clozapine treatment. One case developed a mild rise in troponin-1 levels within one month of clozapine treatment. We also review the current literature on the link between clozapine, myocarditis and cardiomyopathy and suggest clinical guidelines for monitoring patients for cardiac symptoms prior to commencing and while on clozapine treatment.

Myocarditis, pericarditis and cardiomyopathy in patients treated with clozapine

Clozapine is known to cause cardiac side-effects, including myocarditis, pericarditis and cardiomyopathy. Prompted by a case of clozapine-related pericarditis in our hospital we undertook a review of the literature for reports of myocarditis, pericarditis and cardiomyopathy occurring in patients treated with clozapine. This is the first comprehensive review of the literature on this topic.

Adverse cardiac effects associated with clozapine

OBJECTIVE

To review the published literature on serious adverse cardiac events associated with the atypical antipsychotic agent, clozapine, and to make recommendations for cardiac assessment of candidates for clozapine treatment and for monitoring of cardiac status after treatment is initiated.

DATA SOURCES

We searched the PubMed and MEDLINE databases for articles published from 1970 to 2004 that contain the keywords "clozapine and myocarditis," "clozapine and cardiomyopathy," "clozapine and cardiotoxicity," "clozapine and sudden death" or "clozapine and mortality." We also manually searched the bibliographies of these articles for related sources.

STUDY SELECTION

We reviewed the 30 case reports, case series, laboratory and clinical trials, data mining studies, and previous reviews identified by this search.

DATA SYNTHESIS

Recent evidence suggests that clozapine is associated with a low (0.015% to 0.188%) risk of potentially fatal myocarditis or cardiomyopathy. The drug is not known to be independently associated with pathologic prolongation of the QTc interval, but it may contribute to pathologic QTc prolongation in patients with other risk factors for this condition.

CONCLUSIONS

The low risk of a serious adverse cardiac event should be outweighed by a reduction in suicide risk for most patients taking clozapine. We provide recommendations for assessing and monitoring cardiac status in patients prior to and after initiation of treatment with clozapine.

Pericarditis and polyserositis as a side effect of clozapine in an adolescent girl

A case report describes an adolescent girl with a treatment-resistant bipolar disorder, who developed pericarditis and polyserositis while being treated with clozapine. The sparse literature about this rare, severe side effect of clozapine is discussed. Clinical recommendations with regard to monitoring are given. If myocarditis/polyserositis occurs, clozapine has to be discontinued immediately.

Fatalities associated with therapeutic use and overdose of atypical antipsychotics

Since 1989, several novel antipsychotic drugs have become available for use including clozapine, risperidone, olanzapine, quetiapine and ziprasidone. These agents represent a substantial improvement in the treatment of schizophrenia and related disorders and are considered to have a favourable adverse effect profile relative to traditional antipsychotics. Nonetheless, in rare cases, people have died as a result of taking atypical antipsychotic drugs at therapeutic and supratherapeutic doses. Toxic doses of atypical antipsychotics are highly variable: some patients have died while taking therapeutic doses and others have survived massive overdoses. Toxicity may be increased by coingestion of other agents, particularly drugs with similar metabolic pathways. Atypical antipsychotics are metabolised predominantly by cytochrome p450 (CYP) isoenzymes, particularly CYP1A2 (clozapine and olanzapine), CYP3A4 (clozapine, quetiapine and ziprasidone) and CYP2D6 (olanzapine and risperidone). Concurrent prescription of other drugs that inhibit these isoenzymes may increase the probability of adverse events in patients taking atypical antipsychotics. Deaths due to atypical antipsychotic toxicity are often related to cardiovascular complications, but pulmonary, neurological, endocrine and gastrointestinal complications have also caused fatalities. Prevention and management of atypical antipsychotic overdose are of increased clinical relevance as prescription of these drugs increases.

Investigation of the potential of clozapine to cause torsade de pointes

Antipsychotics are frequently associated with QTc interval prolongation, a proposed marker for vulnerability to fatal ventricular arrhythmias, e.g. torsade de pointes (TdP). Little has been published on this topic in relation to clozapine. The objectives of this review were to: (i) calculate the frequency of QTc interval prolongation, T-wave abnormalities, TdP, ventricular tachycardia/fibrillation and sudden unexplained death in patients treated with clozapine and thioridazine from clinical trial and post-marketing reports; (ii) to compare these data with published findings for haloperidol, risperidone, olanzapine, sertindole and ziprasidone; and (iii) to correlate these clinical data with results from preclinical tests presently considered to be of predictive value for a compound's potential to cause QTc interval prolongation and TdP. A review of the global Novartis databases for clozapine and thioridazine and a Medline/Internet search for information on these cardiac events and for preclinical effects on the human ether-a-go-go related gene channels, action potential duration, and QT interval changes produced by the selected antipsychotics were performed. The clozapine database (2.8 million patient-years spanning 27 years) demonstrated that at therapeutic doses all but three reports of QTc interval prolongation and both of TdP were confounded by relevant co-medication/comorbidity. The literature review revealed that all antipsychotics considered except clozapine induced TdP and/or QTc interval prolongation at therapeutic doses. Preclinical in vitro tests appear to overestimate the risk of clozapine, haloperidol and risperidone to prolong QTc interval in patients and underestimate such a risk for sertindole and ziprasidone. Extrapolation of in vitro results to clinical events requires qualified interpretation.