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

Letter to the FDA Proposing Major Changes in the US Clozapine Package Insert Supported by Clozapine Experts Worldwide. Part II: A Review of Fatal Outcomes in US Pharmacovigilance Data and Proposed Changes

PURPOSE/BACKGROUND

This is the second part of a 2-part article that proposes improving the United States (US) clozapine package insert. Part II focuses on fatal outcomes and the 5 boxed warnings, 4 specifically for clozapine: severe neutropenia, seizure, orthostatic hypotension and myocarditis, and 1 for all antipsychotics (elderly with dementia).

METHODS

US reports to the World Health Organization's global pharmacovigilance database were analyzed from clozapine's introduction to January 15, 2023.

FINDINGS/RESULTS

The US was the top reporter worldwide for clozapine with 56,003 reports and 9587 associated fatal outcomes. The 4 clozapine boxed warnings were associated with 534 fatal outcomes (218 with severe neutropenia, 131 with seizures, 125 with orthostasis, 36 with myocarditis, 24 with cardiomyopathy, and 0 with mitral valve prolapse). With no boxed warnings, pneumonia was associated with 674 fatal outcomes and increased white blood cell count (a sign of infection) with 596 fatal outcomes. After considering overlaps, pneumonia and increases in white blood cell count explained 900 fatalities, or 9.4% of 9587 fatal outcomes. The Food and Drug Administration continues to focus on severe neutropenia which was associated with only 218 or 2.3% of fatal outcomes, whereas 97.7% of fatal outcomes reported in US clozapine-treated patients had another cause.

IMPLICATIONS/CONCLUSIONS

To help prevent future deaths in clozapine-treated patients, the clozapine package insert should focus on fatal outcomes during infections. Part II offers detailed solutions regarding current boxed warnings and lack of a warning for pneumonia and other infections. The Supplementary Material includes letters of support from 124 non-US clozapine experts from 44 countries/regions who support Parts I and II.

Relationship Between Clozapine-Induced Inflammation and Eosinophilia: A Retrospective Cohort Study

BACKGROUND AND HYPOTHESIS

Eosinophilia has not been highlighted in clozapine-induced adverse inflammatory events, as it is often asymptomatic and self-limiting, while drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome occurs rarely. This study aimed to reveal the temporal relationships between eosinophilia and other inflammatory events during clozapine initiation.

STUDY DESIGN

The temporal relationships between eosinophilia and other inflammatory events were evaluated among 241 patients with schizophrenia treated with clozapine for the first time at 7 hospitals. Risk factors for eosinophilia were investigated among preceding inflammatory events and other clinical characteristics. Furthermore, patients with eosinophilia were stratified by the severity of adverse inflammatory events and their clinical characteristics were compared.

STUDY RESULTS

Of the 54 patients who experienced inflammatory adverse events, 27 (50%) developed eosinophilia. In all but 1 patient, clinical symptoms of inflammatory adverse events preceded eosinophilia. In contrast, of the 187 patients without inflammatory events, 21 (11%) developed eosinophilia. Multivariate analysis revealed that more severe preceding inflammatory adverse events were associated with a greater risk of eosinophilia. The median time to the first detection of eosinophilia and peak eosinophil count occurred significantly earlier in patients with severe adverse events than in asymptomatic patients.

CONCLUSIONS

In most cases, eosinophilia developed after the onset of inflammatory symptoms. Preceding inflammation was associated with the development of clozapine-induced eosinophilia. Eosinophilia may not be suitable as an early detection marker of severe inflammatory adverse effects. These findings enhanced our understanding of the involvement of eosinophilia in clozapine-induced inflammatory events.

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.

Antipsychotic-Related DRESS Syndrome: Analysis of Individual Case Safety Reports of the WHO Pharmacovigilance Database

INTRODUCTION

Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is gaining attention in pharmacovigilance, but its association with antipsychotics, other than clozapine, is still unclear.

METHODS

We conducted a case/non-case study with disproportionality analysis based on the World Health Organization (WHO) global spontaneous reporting database, VigiBase®. We analyzed individual case safety reports of DRESS syndrome related to antipsychotics compared to (1) all other medications in VigiBase®, (2) carbamazepine (a known positive control), and (3) within classes (typical/atypical) of antipsychotics. We calculated reporting odds ratio (ROR) and Bayesian information component (IC), with 95% confidence intervals (CIs). Disproportionate reporting was prioritized based on clinical importance, according to predefined criteria. Additionally, we compared characteristics of patients reporting with serious/non-serious reactions.

RESULTS

A total of 1534 reports describing DRESS syndrome for 19 antipsychotics were identified. The ROR for antipsychotics as a class as compared to all other medications was 1.0 (95% CI 0.9-1.1). We found disproportionate reporting for clozapine (ROR 2.3, 95% CI 2.1-2.5; IC 1.2, 95% CI 1.1-1.3), cyamemazine (ROR 2.3, 95% CI 1.5-3.5; IC 1.2, 95% CI 0.5-1.7), and chlorpromazine (ROR 1.5, 95% CI 1.1-2.1; IC 0.6, 95% CI 0.1-1.0). We found 35.7% of cases with co-reported anticonvulsants, and 25% with multiple concurrent antipsychotics in serious compared to 8.6% in non-serious cases (p = 0.03). Fatal cases were 164 (10.7%).

CONCLUSIONS

Apart from the expected association with clozapine, chlorpromazine and cyamemazine (sharing an aromatic heteropolycyclic molecular structure) emerged with a higher-than-expected reporting of DRESS. Better knowledge of the antipsychotic-related DRESS syndrome should increase clinicians' awareness leading to safer prescribing of antipsychotics.

Antibiotic-induced severe cutaneous adverse reactions: a single-center retrospective study over ten years

Objective

Severe cutaneous adverse reactions (SCARs) are rare but life-threatening, with antibiotics being the main cause. This retrospective study from a single center was designed to analyze the culprit drugs, clinical features and treatment outcomes of antibiotic-induced SCARs.

Methods

We analyzed cases of antibiotic-induced SCARs in a tertiary hospital in China between January 2013 and January 2024, including Steven-Johnson syndrome (SJS) or Stevens-Johnson syndrome-toxic epidermal necrolysis (SJS-TEN) overlap, toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS) and acute generalized exanthematous pustulosis (AGEP). Descriptive analysis of the demographic characteristics, clinical manifestations, treatment and prognosis were carried out.

Results

Among 354 cases of SCARs, 63 validated antibiotic-related cases were included. Cephalosporins (31.7%), penicillins (25.4%), and quinolones (19.0%) were the most common triggers for SCARs. Overall, liver (50.8%), lungs (31.7%), and kidneys (23.8%) were the most frequently affected organ in SCARs cases. Eight patients (28.6%) in the SJS/SJS-TEN overlap group and 8 patients (80.0%) in the TEN group received combination therapy of corticosteroids and IVIG. Patients with SCARs caused by penicillins or cephalosporins could receive alternative treatments such as lincomamides, quinolones, and tetracyclines. The mortality rate in the TEN group was the highest at 20.0%, followed by the SJS/SJS-TEN overlap group (7.1%), and no deaths were observed in the DRESS and AGEP groups.

Conclusion

The identification of the culprit antibiotics and the application of alternative antibiotic therapies are crucial for the management of antibiotic-induced SCARs. If complicated underlying conditions and complications like advanced age, cancer and pneumonia coexist with SCARs, patients might be more at risk for mortality.

Revealing the reporting disparity: VigiBase highlights underreporting of clozapine in other Western European countries compared to the UK

BACKGROUND

Pharmacovigilance studies indicate clozapine history is marked by adverse drug reactions (ADRs).

OBJECTIVE

In a 2021 article, the United Kingdom (UK) had >90 % of European clozapine-related fatal outcomes in VigiBase, the World Health Organization's pharmacovigilance database. Two possibly opposing hypotheses could explain this disparity: 1) fewer reported fatal outcomes in other Western European countries mainly reflect underreporting to VigiBase, and 2) the higher number of UK reports reflects higher real relative mortality.

METHODS

VigiBase reports from clozapine's introduction to December 31, 2022, were studied for ADRs and the top 10 causes of fatal outcomes. The UK was compared with 11 other top reporting Western countries (Germany, Denmark, France, Finland, Ireland, Italy, Netherlands, Norway, Spain, Sweden and Switzerland). Nine countries (except Ireland and Switzerland) were compared after controlling for population and clozapine prescriptions.

RESULTS

The UK accounted for 29 % of worldwide clozapine-related fatal outcomes, Germany 2 % and <1 % in each of the other countries. The nonspecific label "death" was the top cause in the world (46 %) and in the UK (33 %). "Pneumonia" was second in the world (8 %), the UK (12 %), Ireland (8 %) and Finland (14 %). Assuming that our corrections for population and clozapine use are correct, other countries underreported only 1-10 % of the UK clozapine fatal outcome number.

CONCLUSIONS

Different Western European countries consistently underreport to VigiBase compared to the UK, but have different reporting/publishing styles for clozapine-related ADRs/fatal outcomes. Three Scandinavian registries suggest lives are saved as clozapine use increases, but this cannot be studied in pharmacovigilance databases.

Clozapine-associated pericarditis and pancreatitis in children and adolescents: A systematic literature review and pharmacovigilance study using the VigiBase database

BACKGROUND

The literature has paid very little attention to pericarditis, pericardial effusion and pancreatitis during clozapine treatment in children and adolescents.

METHODS

Cases of clozapine-associated pericarditis and pancreatitis in children were studied using searches in: 1) PubMed (June 16, 2023), and 2) the World Health Organization's pharmacovigilance database (June 1, 2022), VigiBase. VigiBase uses a logarithmic measure of disproportionality called the information component (IC).

RESULTS

The PubMed search yielded 3 clozapine-associated pericarditis cases, 1 pancreatitis case and 1 with both. VigiBase provided a significant clozapine-associated pericarditis IC = 3.6 with an IC025 = 2.9 (only 3 cases were expected while 22 were observed). VigiBase provided a significant clozapine-associated pancreatitis IC = 2.2 with an IC025 = 1.4 (only 3 cases were expected while 16 were observed). In VigiBase clozapine-associated pericarditis and pericardial effusion in youth looked similar and on a continuum with myocarditis, as myocarditis, pericarditis and pancreatitis appeared to occur mainly during clozapine titration. Combining PubMed and VigiBase we identified: 1) 29 cases of at least possible clozapine-associated pericarditis/pericardial effusion (6 probable and 23 possible) including 7 cases with and 22 without myocarditis, and 2) 17 cases of clozapine-associated pancreatitis (1 definite and 16 possible). Two of the pancreatitis cases occurred during overdoses. No fatal outcomes were found in any clozapine-associated pericarditis and pancreatitis cases.

CONCLUSIONS

Despite the lack of attention in the literature to clozapine-associated pericarditis and pancreatitis, results demonstrate that they can happen in youth, particularly during titration. Pericarditis and pancreatitis appear to be forms of clozapine-associated inflammation during dose titration.

Electric Shock Sensation and Recurrent Falls as a Side Effect of Clozapine Therapy: A Case Report

Clozapine is an atypical antipsychotic that acts by blocking mainly dopamine 4 receptors. It is usually prescribed for treatment-resistant schizophrenia as well as treatment-resistant bipolar disorder. Clozapine has a wide profile of side effects that result from blocking different receptors all over the body. A 42-year-old Middle Eastern female is known to have suffered from schizoaffective disorder for many years and had frequent relapses despite compliance with treatment. She was commenced on Clozapine; the patient started complaining of an electric shock sensation throughout her body that resulted in recurrent falls with bilateral leg fractures. She was started on sodium valproate to exclude the possibility of seizure activity but the electric shock sensation did not subside. The decision was made to switch her to aripiprazole and gradually taper down and stop Clozapine which improved her symptoms. Careful monitoring of patients who receive Clozapine is recommended especially during the tapering phase due to the risky adverse events it can bring about. It is essential to understand the side effects in order to tackle them as soon as they arise.

Rethinking Clozapine: Lights and Shadows of a Revolutionary Drug

The current literature globally highlights the efficacy of Clozapine in several psychiatric disorders all over the world, with an FDA indication for reducing the risk of repeated suicidal behavior in patients with schizophrenia or schizoaffective disorder. A growing field of research is also stressing a possible broader beneficial effect of Clozapine in promoting neuroprotection and neurotrophism. However, this drug is linked to several life-threatening side effects, such as agranulocytosis, myocarditis and seizures, that limit its use in daily clinical practice. For this work, a search was performed on PubMed using the terms "Clozapine indications", "Clozapine adverse effects", "Clozapine regenerative effects", and "Clozapine neuroplasticity" with the aim of reviewing the scientific literature on Clozapine's treatment indications, adverse effects and potential regenerative role. The results confirmed the efficacy of clozapine in clinical practice, although limited by its adverse effects. It appears crucial to raise awareness among clinicians about the potential benefits of using Clozapine, as well educating medical personnel about its risks and the early identification of possible adverse effects and their management.

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.

Biologic TNF-α Inhibitors for Stevens-Johnson Syndrome, Toxic Epidermal Necrolysis, and TEN-SJS Overlap: A Study-Level and Patient-Level Meta-Analysis

INTRODUCTION

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are severe cutaneous adverse reactions with high morbidity and mortality and not clearly established treatment protocol. This meta-analysis aimed to evaluate the efficacy and safety of three biologic TNF-α inhibitors (infliximab, etanercept, adalimumab) in the treatment of SJS, SJS-TEN overlap, and TEN.

METHODS

Electronic databases were searched for original studies containing human participants diagnosed with SJS/TEN and treated with biologic TNF-α inhibitors. Individual patient data were collected and summarized to provide a comprehensive overview on therapeutic efficacy of different biologic TNF-α inhibitors for SJS, SJS-TEN overlap, and TEN, respectively. Meta-analyses on aggregated study data were conducted using random-effects model.

RESULTS

Overall, 55 studies with 125 sets of individual patient data were included. Infliximab was used to treat 3 patients with SJS-TEN overlap and 28 patients with TEN, and the actual mortality rate was 33.3% and 17%, respectively. Etanercept was administered to 17 patients with SJS, 9 patients with SJS-TEN overlap, and 64 patients with TEN, and mortality rate was reported to be 0%, 0%, and 12.5%, respectively. For participants with TEN, no significant difference was found in time of reepithelialization, hospitalization time, and mortality rate comparing etanercept with infliximab. More sequelae were reported in patients receiving infliximab than in patients treated with etanercept (39.3% versus 6.4%). Adalimumab was administered to four patients with TEN, and mortality rate was 25%. Meta-analyses on aggregated study data revealed significantly shortened hospitalization time in etanercept compared with non-etanercept groups [weighted mean differences (WMD) -5.30; 95% confidence interval (CI) -8.65 to -1.96]. Etanercept was associated with a survival benefit for patients when compared with non-etanercept treatment, however, the analysis was not statistically significant (odds ratio 0.55; 95% CI 0.23-1.33).

CONCLUSIONS

On the basis of the current findings, etanercept is currently the most promising biologic therapy for SJS/TEN. Further evaluation in prospective studies is required to confirm its efficacy and safety.

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.

Screening the European pharmacovigilance database for reports of clozapine-related DRESS syndrome: 47 novel cases

Clozapine-related drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is a rare adverse reaction. We aimed to screen a large pharmacovigilance database to identify clozapine-related DRESS cases, even if otherwise reported and provide a clinical overview. We screened spontaneous reports of clozapine-related DRESS syndrome in EudraVigilance database applying the European Registry on Severe Cutaneous Adverse Drug Reactions (RegiSCAR) criteria and scores to identify probable/definite DRESS syndrome cases. Clinical and demographic characteristics of included cases were provided and associations between RegiSCAR scores, and time to develop/recover DRESS were assessed. In a total of 262,146 adverse drug reactions reports for 75,190 clozapine-treated patients, 596 cases fulfilled RegiSCAR criteria; ultimately, 51 cases were rated as probable/definite DRESS according to RegiSCAR scores, of which 4 were previously published as case reports. The mean age of patients was 41.06 years (43.1% females), with 13 patients (25.5%) receiving reported co-medication with other DRESS culprit drugs. Median time between clozapine initiation and DRESS symptoms was 25 days. Clozapine dose was associated with days to develop symptoms (Spearman's ρ 0.40, p = 0.03). Organ involvement was reported in all cases followed by fever (n = 49; 96.1%) and eosinophilia (n = 47; 92.2%). Treatment involved clozapine discontinuation for 37 patients (72.5%), while 3.9% (n = 2) of cases ended fatally. Clozapine rechallenge was undertaken in 25 patients (49.0%). The screening of the EudraVigilance database revealed 47 novel clozapine-related DRESS cases, and only one was originally reported as DRESS. Clozapine-related DRESS may occur with clozapine monotherapy not only during dose titration, but also during maintenance treatment.

Clozapine Management in Schizophrenia Inpatients: A 5-Year Prospective Observational Study of Its Safety and Tolerability Profile

BACKGROUND

Clozapine is well known for its efficacy and clinical superiority compared to other antipsychotics in treatment-resistant schizophrenia (TRS). However, it is frequently underutilized worldwide because of its acute adverse events, as well as for its long-term cardiometabolic and hematological consequences.

OBJECTIVE

The aim of the study was to evaluate 5-year safety in chronic TRS inpatients with continuous clozapine use.

METHODS

Patients with TRS and clozapine treatment were evaluated for 5 years. All participants were assessed using the Brief Psychiatric Rating Scale (BPRS), Glasgow Antipsychotic Side-effect Scale for Clozapine (GASS-C), Social Performance Scale (PSP) and Short Portable Mental Status Questionnaire (SPMSQ). Clinical, cardiometabolic and hematological data were collected periodically. General linear models (GLM) repeated measures controlling for CLZ dose were utilized to determine differences in variables across the time.

RESULTS

Overall, 189 inpatients were screened for study participation. The final sample included twenty-one TRS patients (16 males, 76%) with an average age of 57.6 years, all with 5-year continuous use of clozapine (mean dose 266 mg/day). There was not a significant effect of time on BPRS (p=0.774), PSP (p=0.855) and SPMSQ (p=0.066); differences remained not significant after controlling for CLZ dose (p=0.585, p=0.467 and p=0.105, respectively). No changes were found in blood and clinical parameters except for red blood cell count, which decreased over time (p=0.024; η2= 0.952). Patients reported a significant BMI decrease (-8.98 kg, p=0.008) between baseline and 5 years last observation.

CONCLUSION

The findings show how the application of a structured dietary, clinical and therapeutic monitoring program in psychiatric care facilities could allow the safe and effective long-term cardiometabolic and hematological management of clozapine. The unique role that clozapine plays in the current treatment of patients with TRS requires greater clinical awareness. Although its acute and chronic side effects are notorious, its safety management is feasible and broadens its potential practical application.