Clozapine-Induced Serositis: Review of Its Clinical Features, Pathophysiology and Management Strategies

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.

Clozapine in a Young Female with Drug-Resistant Schizophrenia: A Case Report of Development of Serositis

BACKGROUND

Clozapine may be considered the first-line option for treatment-resistant schizophrenia (TRS), a condition that occurs in more than 30% of patients with schizophrenia. Despite its efficacy for treating TRS, clozapine use is limited by the occurrence of several adverse effects in more than 70% of cases. Clozapine does not typically affect lung function, although a few cases have been reported in the literature.

CASE PRESENTATION

To gain a better understanding of this rare event, here we report the case study of a young female with TRS, who was treated with clozapine and developed medium and bilateral pleural effusion relief with contiguous atelectasis and polyserositis. Two weeks after stopping clozapine, the follow-up chest scan showed complete remission of the pulmonary condition. We postulate that clozapine might have caused, in this case, a specific immunoinflammatory response leading to serosal complications.

CONCLUSION

Although the underlying mechanisms of this adverse effect are not completely understood, early manifestations, such as benign eosinophilia, fever, and flu-like symptoms need to be considered a potential warning to facilitate an early diagnosis and carefully manage pulmonary complications related to clozapine treatment.

Recognition and management of clozapine adverse effects: A systematic review and qualitative synthesis

OBJECTIVE

Clozapine is substantially underutilized in most countries and clinician factors including lack of knowledge and concerns about adverse drug effects (ADEs) contribute strongly to treatment reluctance. The aim of this systematic review was to provide clinicians with a comprehensive information source regarding clozapine ADEs.

METHODS

PubMed and Embase databases were searched for English language reviews concerned with clozapine ADEs; publications identified by the automated search were manually searched for additional relevant citations. Following exclusion of redundant and irrelevant reports, pertinent information was summarized in evidence tables corresponding to each of six major ADE domains; two authors reviewed all citations for each ADE domain and summarized their content by consensus in the corresponding evidence table. This study was conducted in accordance with PRISMA principles.

RESULTS

Primary and secondary searches identified a total of 305 unique reports, of which 152 were included in the qualitative synthesis. Most clozapine ADEs emerge within 3 months, and almost all appear within 6 months, after initiation. Notable exceptions are weight gain, diabetic ketoacidosis (DKA), severe clozapine-induced gastrointestinal hypomotility (CIGH), clozapine-induced cardiomyopathy (CICM), seizures, and clozapine-induced neutropenia (CIN). Most clozapine ADEs subside gradually or respond to dose reduction; those that prompt discontinuation generally do not preclude rechallenge. Rechallenge is generally inadvisable for clozapine-induced myocarditis (CIM), CICM, and clozapine-induced agranulocytosis (CIA). Clozapine plasma levels >600-1000 μg/L appear more likely to cause certain ADEs (e.g., seizures) and, although there is no clear toxicity threshold, risk/benefit ratios are generally unfavorable above 1000 μg/L.

CONCLUSION

Clozapine ADEs rarely require discontinuation.

Clozapine induced pericarditis: A case report

Clozapine is a second-generation antipsychotic often used for treatment-refractory schizophrenia and has many adverse effects. Cardiac adverse events potentiated by clozapine include myocarditis which is a black box warning. Even more rarely, there are multiple cases of pericarditis reported in the literature. This is a case report of a 32-year old male with paranoid schizophrenia who developed pericarditis after initiation and titration of clozapine in the inpatient psychiatry unit. Patient presented with chest pain, persistent tachycardia, and orthostatic hypotension two weeks after titration of clozapine. The diagnosis of pericarditis was supported by the repeat electrocardiogram which revealed PR depressions, the audible friction rub, and the pleuritic/episodic nature of the chest pain. All other possible causes of pericarditis were ruled out and clozapine was suspected as the most likely explanation. The pericarditis resolved with treatment of colchine and ibuprofen on evidence from a repeat echocardiogram. This case report demonstrates and supports few cases of clozapine induced pericarditis in the literature. Cardiac events of clozapine can be life-threatening; therefore, greater baseline and subsequent cardiac monitoring may be implicated in the future.

Challenges in Prescribing Clozapine in the Era of COVID-19: A Review Focused on Immunological Implications

The global COVID-19 pandemic has disrupted every aspect of the healthcare system. Apart from the issues surrounding COVID-19 itself, care for existing patients has met many challenges. One such challenge is caring for patients who are on clozapine treatment and have been confirmed positive for COVID-19. Schizophrenia has been considered to have a deep connection with the immune system, and clozapine can induce further changes in this system. COVID-19 can ravage the compromised immune system and aggravate tissue damage. The intricate relations between schizophrenia, clozapine, and COVID-19 make it difficult to predict the clinical course of COVID-19 in clozapine-treated patients. However, the rigid prohibition on using clozapine if COVID-19 is confirmed may harm patients. Patients who have to use clozapine are often refractory cases with no alternatives. Therefore, the decision to maintain or stop clozapine must be made after a comprehensive review of the patient’s unique situation. To do this, theoretical and practical issues surrounding the use of clozapine in COVID-19 should be reviewed and discussed. In this review, we gather useful information surrounding this issue and present an overview. Focusing on the immune system, various theoretical possibilities that could arise from schizophrenia, clozapine, and COVID-19 were carefully examined, and practical checklists for the care of these patients were explored. It is hoped that this review will convince many clinicians to pay attention to this momentous issue and facilitate more active sharing of clinical experiences.

Clinical Utility and Safety of Slower-than-Recommended Titration of Clozapine for Treatment-Resistant Schizophrenia: a Retrospective Cohort Study

Slow titration of clozapine is recommended given the risk of serious adverse effects. However, the utility and safety of slower-than-recommended titration of clozapine remain unclear. Consequently, we aimed to investigate the clinical utility and safety of slower-than-recommended titration of clozapine for treatment-resistant schizophrenia. We conducted a retrospective chart review of 152 inpatients with treatment-resistant schizophrenia who had been newly started on clozapine in a tertiary psychiatric public hospital between April 2012 and March 2018. The primary outcome was clozapine continuation for the first 18 weeks. We performed multivariate logistic regression to identify the association between the rate of clozapine dose titration and clozapine continuation for the first 18 weeks. Among the 152 inpatients, 122 (80%) could continue clozapine for the first 18 weeks. There was no significant association between the rate of clozapine dose titration and clozapine continuation for the first 18 weeks (adjusted odds ratio 1.23; 95% CI 0.29-5.26; p = 0.78). Our findings indicate that slower-than-recommended titration of clozapine may not improve toward clozapine continuation for the first 18 weeks. Therefore, it may not be a beneficial option in terms of safe clozapine continuation when starting clozapine for treatment-resistant schizophrenia.

Clinical determinants of fever in clozapine users and implications for treatment management: A narrative review

OBJECTIVES

To identify the clinical determinants of fever in clozapine users and their impact on management of clozapine treatment.

METHODS

Articles published in English or French identified with a MEDLINE, Web of Sciences, Cochrane Library and PsycINFO search, from inception through February 2019, using the term "clozapine" in combination with "fever" OR "hyperthermia" OR "body temperature" OR "pyrexia" OR "febrile" OR "heat" OR "thermoregulation". Information extracted for each medical condition were frequency, time to onset after initiation of clozapine treatment, characteristics of fever, associated symptoms, laboratory tests used for diagnosis, course, lethality, discontinuation of clozapine. Data were synthesized narratively.

RESULTS

Our search yielded 394 unique hits published from 1993 to 2018. We included 73 articles in the review: two meta-analyses, 14 reviews, six epidemiological studies, 11 clinical studies and 40 case reports. During clozapine initiation, fever is most frequently benign and transient but should be closely monitored as it may be the first stage of potentially life-threatening adverse drug reactions (ADR) (agranulocytosis, neuroleptic malignant syndrome myocarditis, hepatitis, pancreatitis, nephritis, colitis, etc.). Other ADR associated with fever are independent of duration of exposure to clozapine (heat stroke, pneumonia, pulmonary embolism, necrotizing colitis). If fever is due to intercurrent infection, therapeutic drug monitoring is recommended to adjust clozapine daily dosage.

CONCLUSION

Benign causes of fever are much more frequent than life-threatening ADR during clozapine treatment. Discontinuation should not be considered as automatic in the event of fever, especially during the early phase of clozapine initiation.

Clozapine-induced pericarditis: an ethical dilemma

Clozapine is an atypical antipsychotic used most frequently in the management of treatment-resistant schizophrenia, where severely unwell patients have failed to respond to standard antipsychotic therapy. Clozapine is associated with a number of risks, such as agranulocytosis and long-term cardiometabolic morbidity. Reported less frequently is the risk of severe cardiac complications. The case reported here provides an important example of chronic clozapine toxicity leading to pericarditis. This case also describes a difficult ethical dilemma, where the physical risk to a patient with a diagnosis of schizophrenia must be balanced with the potentially adverse psychiatric risk that would follow, if the patient were to be weaned off this effective antipsychotic therapy. It is frequently reported that clozapine is stopped due to its toxicity. In this case however, the mental health and functional benefit of continuing with clozapine was deemed to outweigh the physical risk of progression of the pericarditis.

Olanzapine Associated Acute Peripheral Edema and Pericardial Effusion: A Case Report

Olanzapine is a potent atypical antipsychotic drug used for the treatment of schizophrenia and bipolar disorder with approved efficiency. Olanzapine is superior to the typical antipsychotic drugs with low incidence of extrapyramidal side effects, especially tardive dyskinesia. The most common side effects associated with olanzapine are constipation, dyspepsia, weight gain, somnolence, asthenia, dry mouth and dizziness. Peripheral edema associated with olanzapine is rarely reported and as far as we know there is no report in the literature about peripheral edema concomitant with pericardial effusion related to olanzapine. The mechanism of these side effects associated with olanzapine is still unclear and there are different hypotheses in the literature. Herein we report the first case that developed both peripheral edema and pericardial effusion after olanzapine administration. Although very rarely encountered, clinicians should be aware of these possible side-effects.

Polyserositis: a diagnostic challenge

BACKGROUND

Polyserositis (PS) is the inflammation, with effusion, of different serous membranes. It has been associated with different aetiologies, but the aetiology of PS remains unknown in a high percentage of patients.

AIMS

The general objective of this retrospective study was to analyse the aetiology of PS cases seen at Son Llàtzer Hospital in an 11-year period. Other objectives were to determine the epidemiological, clinical and analytical characteristics of these patients.

METHODS

An observational, descriptive and retrospective study to analyse the aetiology of PS cases seen at Son Llàtzer Hospital. The inflammation of two or more serous membranes confirmed by an imaging test was required and at least one of the serous fluid should be an exudate.

RESULTS

A total of 92 patients was included in the study. The most common diagnosis was neoplasm (nearly one-third of cases) followed by infectious and autoimmune diseases. PS aetiology was unknown in more than one-third. Pleura and pericardium were the most common sites of serosal involvement (83%). Antinuclear antibodies' positivity in serum and increased levels of adenosine deaminase in pleural effusion were significantly associated with a final diagnosis of autoimmune disease. Increased pleural lactate dehydrogenase levels were significantly associated with a final diagnosis of neoplasm. In 9 of 14 patients with a previous cancer, PS represented a recurrence of their cancer. Cases of unknown aetiology presented most frequently as pleural and pericardial involvement, and the majority resolved. In very few patients, an infectious aetiology could be proven.

CONCLUSION

PS is a frequent clinical entity that is associated with different diseases and its diagnosis could be challenging, with a high rate of unknown aetiologies.

Hepatitis, Interstitial Nephritis, and Pancreatitis in Association With Clozapine Treatment: A Systematic Review of Case Series and Reports

PURPOSE/BACKGROUND

Clozapine is the criterion standard in treatment-resistant schizophrenia. We sought to review data on several inflammatory effects associated with clozapine, specifically interstitial nephritis, hepatitis, and pancreatitis.

METHODS/PROCEDURES

We conducted a systematic review to identify studies, published up until December 2017, describing clozapine-induced hepatitis, nephritis, and pancreatitis. The primary objective was to characterize the clinical characteristics associated with each of the specific inflammatory reactions to clozapine.

FINDINGS/RESULTS

We identified 42 cases of inflammatory reactions associated with clozapine treatment- 20 :cases of clozapine-induced hepatitis, 11 cases of nephritis, and 11 of pancreatitis. The mean (SD) age was 38.8 (11.9) years. The mean (SD) dose of clozapine used was 252.4 (133.7) mg. Time to onset of pancreatitis (17.9 [11.2] days; range 4-35 days) was shorter than that for hepatitis (34.2 [20.1] days; range, 12-90 days) and nephritis (27.9 [27.0]; range, 8-90 days) but was not statistically significant (F = 2.267, P = 0.117). The mean (SD) time to recovery was shorter for cases of pancreatitis (15.7 [18.4] days) compared with cases of hepatitis (25.9 [16.5] days) and nephritis (24.5 [18.9] days). Three cases with hepatitis died. Seven of the cases had a clozapine rechallenge (hepatitis [n = 3], nephritis [n = 1], pancreatitis [n = 3]), with 5 having a recurrence at a mean (SD) onset of 3.5 (2.5) days (range, 1-7 days); 2 hepatitis cases were successfully rechallenged.

IMPLICATIONS/CONCLUSIONS

Clozapine-induced hepatitis, nephritis, and pancreatitis are uncommon adverse events, reflected in the paucity of case studies in the literature. Early recognition of the signs and symptoms of clozapine-associated hepatitis, nephritis, and pancreatitis is important, as when identified, clozapine should be urgently discontinued. Clozapine is associated with evidence of benign inflammatory processes; the extent to which hepatitis, and other inflammatory reactions, may be on a continuum with these more benign and self-limiting reactions is unclear, and this can only be resolved by prospectively following cohorts of clozapine-treated patients.

Burning pain secondary to clozapine use: a case report

BACKGROUND

The first of the atypical antipsychotics introduced in the 1970s, clozapine remains the most efficacious neuroleptic to this day. However, serious and potentially fatal side effects have necessitated careful regular monitoring among prescribing clinicians. Some adverse effects (e.g. ischaemic bowel) remain under recognized, while newly identified adverse effects continue to be described in the literature.

CASE PRESENTATION

In this report, we describe a healthy 43-year old Caucasian male who experienced onset of a full body deep burning pain several months after the onset of treatment with clozapine. The pain worsened over time, ceased with cessation of treatment, and returned soon after the patient was rechallenged.

CONCLUSION

We describe an unusual adverse effect from clozapine treatment that has not been described elsewhere to our knowledge. We present the time course of the pain symptom, relationship to dose, associated laboratory results, and ultimately how it was dealt with and how it improved for the benefit of clinicians who may encounter it in the future.

The neuroimmunology of schizophrenia

Schizophrenia (SCZ) is a polygenic, multi-factorial disorder and a definitive understanding of its pathophysiology has been lacking since it was first described more than a century ago. The predominant pharmacological approach used to treat SCZ is the use of dopamine receptor antagonists. The fact that many patients remain symptomatic, despite complying with medication regimens, emphasises the need for a more encompassing explanation for both the causes and treatment of SCZ. Recent neuroanatomical, neurobiological, environmental and genetic studies have revived the idea that inflammatory pathways are involved in the pathogenesis of SCZ. These new insights have emerged from multiple lines of evidence, including the levels of inflammatory proteins in the central nervous system of patients with SCZ and animal models. This review focuses on aberrant inflammatory mechanisms present both before and during the onset of the psychotic symptoms that characterise SCZ and discusses recent research into adjunctive immune system modulating therapies for its more effective treatment.

Immunomodulatory effects of clozapine and their clinical implications: what have we learned so far?

Clozapine remains the drug of choice for treatment resistant schizophrenia, but is associated with potentially life threatening side effects, including agranulocytosis and myocarditis. Immunological mechanisms may be involved in the development of these side effects or in the unique antipsychotic efficacy in subgroups of schizophrenia patients. This systematic review presents the immunomodulatory effects of clozapine from human in vitro and in vivo studies and relates these findings to the developments of adverse and therapeutic effects of clozapine. Several studies confirm the immunomodulatory actions of clozapine, but only few studies investigated their relationship to the unique adverse and therapeutic effects of clozapine. During the first month of clozapine treatment, up to 50% of patients develop fever and flu like symptoms, which is seemingly driven by increased cytokines. Within the same time period, the risk of side-effects with a suspected immunological mechanism peaks. Patients developing fever during the first weeks of treatment should have a thorough physical examination, and measurements of white blood cell count, absolute neutrophil count, ECG, C-reactive protein, creatinine kinase, and troponin to exclude infection, agranulocytosis, myocarditis and neuroleptic malignant syndrome. To what degree the unique antipsychotic efficacy of clozapine in subgroups of schizophrenia patients is related to its immunomodulatory effects has not been studied. Research relating the immunomodulatory actions of clozapine and its early markers to clinically relevant adverse and therapeutic outcomes is hoped to provide new leads for the understanding of the pathophysiology of schizophrenia and aid the development of novel treatment targets.