An international guideline with six personalised titration schedules for preventing myocarditis and pneumonia associated with clozapine

Clozapine for persons with neurodevelopmental disorders: a systematic review and expert recommendations for clinical practice

INTRODUCTION

We aimed to synthesize the information on the risks and benefits of clozapine prescription for resistant challenging behavior in persons with neurodevelopmental disorders.

METHODS

Articles were identified with MEDLINE, Web of Sciences, and PsycINFO search from inception through January 2024. The review was restricted to persons with intellectual disability (ID) and/or autism spectrum disorder (ASD) without comorbid psychotic or affective disorder. Data were synthesized narratively.

RESULTS

We identified 24 articles (13 case reports, eight chart studies, two controlled studies, one pharmaco-epidemiological study) including 296 patients with ID (n = 222) or ASD (n = 74) (10% aged ≤ 18 years). After clozapine initiation, a decreased frequency of challenging behavior persisting over time was reported in most participants included in clinical studies, and a significant reduction in the number of admissions in the population-based two-year mirror-image study. Adverse drug reactions were those commonly observed with clozapine, i.e. constipation, sedation, and weight gain.

CONCLUSIONS

Since only four participants were included in the controlled studies, the benefits of clozapine in neurodevelopmental disorders are supported by a body of evidence exclusively drawn from observational studies. Further studies are required to clarify the indications of clozapine with respect to the unmet need induced by resistant challenging behavior.

REGISTRATION

PROSPERO database registration number CRD42024522343.

Effects of titration speed, gender, obesity and concomitant medications on the risk and onset time of clozapine-associated fever among Japanese patients with schizophrenia: retrospective review of charts from 21 hospitals

BACKGROUND

Clozapine-induced inflammation, such as myocarditis and pneumonia, can occur during initial titration and can be fatal. Fever is often the first sign of severe inflammation, and early detection and prevention are essential. Few studies have investigated the effects of clozapine titration speed and concomitant medication use on the risk of clozapine-induced inflammation.

AIMS

We evaluated the risk factors for clozapine-associated fever, including titration speed, concomitant medication use, gender and obesity, and their impact on the risk of fever and the fever onset date.

METHOD

We conducted a case-control study. The medical records of 539 Japanese participants with treatment-resistant schizophrenia at 21 hospitals in Japan who received clozapine for the first time between 2010 and 2022 were retrospectively investigated. Of these, 512 individuals were included in the analysis. Individuals were divided into three groups according to the titration rate recommended by international guidelines for East Asians: the faster titration group, the slower titration group and the ultra-slower titration group. The use of concomitant medications (such as antipsychotics, mood stabilisers, hypnotics and anxiolytics) at clozapine initiation was comprehensively investigated. Logistic regression analysis was performed to identify the explanatory variables for the risk of a fever of 37.5°C or higher lasting at least 2 days.

RESULTS

Fever risk significantly increased with faster titration, male gender and concomitant use of valproic acid or quetiapine. No increased fever risk was detected with the use of other concomitant drugs, such as olanzapine, lithium or orexin receptor antagonists. Fever onset occurred significantly earlier with faster titration. Multivariate analysis identified obesity as being a factor that accelerated fever onset.

CONCLUSION

A faster titration speed and concomitant treatment with valproic acid and quetiapine at clozapine initiation increased the risk of clozapine-associated fever. Clinicians should titrate clozapine with caution and consider both the titration speed and concomitant medications.

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.

Clozapine safety monitoring and related research in psychiatry and neurology in South America: A scoping review

The quality and quantity of clozapine safety monitoring considerably differs among South American countries and mainly focus on hematological surveillance. Few studies have been conducted on other clozapine-related adverse effects (ADRs) and mainly refer to case reports and literature reviews. We retrieved thirty-nine publications on clozapine related ADRs others than neutropenia. Studies in Brazil and Venezuela accounted for 67 % of all the publications, and 8 out of 12 countries published 2 or less manuscripts. Only Chile offers serum clozapine level measurement in public institutions. Given the recently recognized role of ethnicity, gender, smoking, obesity drug interactions in optimal clozapine administration, modernization of clozapine clinical use and research in psychiatry and neurology most be broadcasted and stimulated in South American countries.

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.

The cellular mechanism of antipsychotic-induced myocarditis: A systematic review

Antipsychotic drug-induced myocarditis is a serious and potentially fatal adverse drug reaction characterized by inflammation of the heart muscle (myocardium) that typically develops within the first month after commencing an antipsychotic drug. Although the precise mechanism of this severe adverse drug reaction is unknown, multiple theories have been proposed with varying levels of support from cellular or animal studies. We conducted a systematic review, in accordance with PRISMA guidelines, of published preclinical and clinical studies investigating the cellular mechanism by which antipsychotic drugs induce myocarditis. A literature search including all studies available before December 10, 2022, yielded 15 studies that met our inclusion criteria. Antipsychotics examined in the included studies included clozapine (n = 13), ziprasidone (n = 1), amisulpride (n = 1), haloperidol (n = 1), levomepromazine (n = 1), olanzapine (n = 1), and sertindole (n = 1). The evidence suggests several overlapping mechanistic cascades involving: (1) increased levels of catecholamines, (2) increased proinflammatory cytokines, (3) increased reactive oxygen species (ROS), (4) reduced antioxidant levels and activity, and (5) mitochondrial damage. Notable limitations such as, a focus on clozapine, sample heterogeneity, and use of supratherapeutic doses will need to be addressed in future studies. Discovery of the mechanism by which antipsychotic drugs induce myocarditis will allow the development of clinically-useful biomarkers to identify those patients at increased risk prior to drug exposure. The development or repurposing of therapeutics to prevent or treat drug-induced myocarditis will also be possible and this will enable increased and safe use of antipsychotics for those patients in need.

Escaping the Long Shadow Cast by Agranulocytosis: Reflections on Clozapine Pharmacovigilance Focused on the United Kingdom

PURPOSE/BACKGROUND

A recent article in this journal presented a US perspective regarding the modernization of clozapine prescription and proposed an escape from the long shadow cast by agranulocytosis.

METHODS

Here, an international group of collaborators discusses a point of view complementary to the US view by focusing on worldwide outcomes of clozapine usage that may be uneven in terms of frequency of clozapine adverse drug reactions.

FINDINGS/RESULTS

Studies from the Scandinavian national registries (Finland and Denmark) did not find increased mortality in clozapine patients or any clear evidence of the alleged toxicity of clozapine. Data on clozapine-associated fatal outcomes were obtained from 2 recently published pharmacovigilance studies and from the UK pharmacovigilance database. A pharmacovigilance study focused on physician reports to assess worldwide lethality of drugs from 2010 to 2019 found 968 clozapine-associated fatal outcomes in the United Kingdom. Moreover, the United Kingdom accounted for 55% (968 of 1761) of worldwide and 90% (968 of 1073) of European fatal clozapine-associated outcomes. In a pharmacovigilance study from the UK database (from 2008 to 2017), clozapine was associated with 383 fatal outcomes/year including all reports from physicians and nonphysicians. From 2018 to 2021, UK clozapine-associated fatal outcomes increased to 440/year.

IMPLICATIONS/CONCLUSIONS

The interpretation of fatal outcomes in each country using pharmacovigilance databases is limited and only allows gross comparisons; even with those limitations, the UK data seem concerning. Pneumonia and myocarditis may be more important than agranulocytosis in explaining the uneven distribution of fatal outcomes in clozapine patients across countries.

Respiratory aspiration during treatment with clozapine and other antipsychotics: a literature search and a pharmacovigilance study in VigiBase

INTRODUCTION

Antipsychotics (APs), during treatment or overdose, may be associated with respiratory aspiration.

AREAS COVERED

A PubMed search on September 30, 2022, provided 3 cases of respiratory aspiration during clozapine therapy and 1 case during an AP overdose. VigiBase records of respiratory aspiration associated with APs from inception until September 5, 2021, were reviewed. VigiBase, the World Health Organization's global pharmacovigilance database, uses a statistical signal for associations called the information component (IC).

EXPERT OPINION

The ICs (and IC₀₂₅) were 2.1 (and 2.0) for APs, 3.2 (and 3.0) for clozapine, 2.6 (and 2.4) for quetiapine, and 2.5 (and 2.2) for olanzapine. Cases of respiratory aspiration associated with APs included: 137 overdose/suicide cases (64 fatal) and 609 cases during treatment (385 fatal) including 333 taking clozapine (238 fatal). In logistic regression models of fatal outcomes, the odds ratios, OR, and (95% confidence intervals, CI) of significant independent variables were: a) 2.3 - 2.6 for clozapine in 3 samples of AP treatment of varying size, b) 1.9 (CI 1.0 to 3.5) for geriatric age in 284 patients on clozapine treatment, and c) 1.8 (CI 1.1 - 3.2) for antidepressant co-medication in 276 patients on non-clozapine APs. Multiple AP pharmacological mechanisms may explain respiratory aspiration.

Reflections on the Lack of Consideration of Ethnic Ancestry to Stratify Clozapine Dosing

This review article argues against trusting standard clozapine references, including the US package insert, because they do not include advances in the sciences of pharmacokinetics and pharmacovigilance and ignore the effects of ethnic ancestry on therapeutic dosing. The minimum therapeutic dose leading to the minimum therapeutic concentration of 350 ng/mL in serum/plasma can be used to compare individuals/groups with treatment-resistant schizophrenia. The US clozapine package insert recommends targeting doses of 300-450 mg/day and, subsequently, increments of up to 100 mg with a maximum dose of 900 mg/day. Ethnic ancestry is defined by DNA ancestry group. Asians (people with ancestry ranging from Pakistan to Japan) and Indigenous Americans are similar in clozapine dosing; their average clozapine minimum therapeutic dose ranged from 166 mg/day (female non-smokers) to 270 mg/day (male smokers). For those with European ancestry, average clozapine minimum therapeutic doses ranged from 236 mg/day (female non-smokers) to 368 mg/day (male smokers). Based on limited studies, Black (African sub-Saharan ancestry) patients may be treated with typical US doses (300-600 mg/day), assuming no poor metabolism (PM) status. Ancestry's impact on clozapine lethality in four countries is discussed (two countries with highly homogenous populations, Denmark and Japan, and two countries with increasingly heterogenous populations due to immigration, Australia and the UK). An international guideline with 104 authors from 50 countries/regions was recently published, providing 6 personalized clozapine titration schedules for adult inpatients (3 ancestry groups and PM/non-PM schedules) and recommending c-reactive protein monitoring at baseline and weekly for 4 weeks.

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.

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.