Adverse drug reactions and their fatal outcomes in clozapine patients in VigiBase: Comparing the top four reporting countries (US, UK, Canada and Australia)

Pharmacovigilance in Action: Utilizing VigiBase Data to Improve Clozapine Safety

Purpose

Clozapine is an antipsychotic which was approved in 1989 for treatment-resistant schizophrenia in the United States (US). There were few randomized trials before its approval and potentially lethal clozapine adverse drug reactions (ADRs), such as agranulocytosis and myocarditis were identified by pharmacovigilance. VigiBase, the WHO global database, is a cornerstone of international pharmacovigilance efforts for ADR identification during post-marketing surveillance. This systematic review of the literature explores additional contributions to the knowledge of clozapine ADRs from recent VigiBase studies.

Methods

Using the terms "clozapine AND VigiBase" we conducted an article search in PubMed on September 5, 2024. Of the 29 articles, 11 were excluded and 18 described in the Results section.

Results

All clozapine ADRs were described in two VigiBase studies. One on pregnancy indicated no increased risk with clozapine compared with other antipsychotics; the other reported 191,557 clozapine ADRs, including 22,956 fatal outcomes through January 15, 2023, and paid attention to the reporting style of the top 4 reporting countries (the US, the United Kingdom, Canada and Australia). Infections were described in three VigiBase studies where clozapine treatment was associated with infections, respiratory aspiration, and pneumonia. Rapid titration can lead to localized clozapine-induced inflammations including myocarditis, pericarditis or pancreatitis, or generalized inflammations such as drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome. Clozapine-induced inflammation was described in four VigiBase studies, two focused on all ages (myocarditis and DRESS) and two on youth (myocarditis and another on pericarditis and pancreatitis). Other specific ADRs were described in nine VigiBase studies (hematological malignancies, rhabdomyolysis, sialorrhea, seizures, diabetes mellitus, drug-induced parkinsonism, withdrawal symptoms, and suicidal behaviors).

Conclusion

The spectrum of respiratory aspiration - aspiration pneumonia - pneumonia and other infections are significant causes of fatal outcomes in clozapine-treated patients. Clozapine had anti-suicidal effects versus other antipsychotics across all VigiBase labels of suicidal behavior.

Clozapine may consistently protect from suicidal behaviors while other antipsychotics may lack a specific protective effect: a comprehensive VigiBase study interpreted in the context of the prior literature

BACKGROUND

In the United States, clozapine was first approved for treatment-resistant schizophrenia and then for suicidality in schizophrenia psychoses. Systematic reviews support clozapine's anti-suicidal effect, but the forensic literature stresses its lethality during overdoses.

RESEARCH DESIGN AND METHODS

Clozapine reports to the international pharmacovigilance database (VigiBase) were analyzed for suicidal ideation, suicide attempts, intentional overdose, and completed suicides from introduction to 1 January 2024. VigiBase uses the information component (IC) as a disproportionality analysis.

RESULTS

The clozapine ICs (range: other antipsychotics) were: 1) suicidal ideation IC = 0.570 with IC025 = 0.454 to IC975 = 0.680 (IC = 3.568 for aripiprazole and 1.729 for risperidone), 2) suicide attempt IC = 1.428 with IC025 = 1.323 to IC975 = 1.529 (IC = 4.150 for quetiapine and 2.968 for risperidone), 3) intentional overdose: IC = 0.995 with IC025 = 0.864 to IC975 = 1.120 (IC = 4.080 for quetiapine and 1.957 for aripiprazole), and 4) completed suicide IC = 1.133 with IC025 = 1.026 to IC975 = 1.235 (IC = 4.648 for quetiapine and 2.160 for risperidone). In summary, all clozapine ICs were significantly lower. We found 2391 clozapine-treated patients on the suicidality spectrum (627 cases with suicidal ideation, 752 with suicide attempt, 488 with intentional overdose, and 731 with completed suicide) but many were taking other antipsychotics. The most frequent reporting countries were the United States, the United Kingdom, and Croatia.

CONCLUSION

This pharmacovigilance study, with all its inherent limitations, provides independent proof, not overlapping with prior literature, that clozapine may have specific strong anti-suicidal effects that do not appear to be present in other antipsychotics. Further VigiBase studies are needed to compare the lethality of an intentional overdose of clozapine (14.3%) with other antipsychotics.

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.

Investigating in VigiBase over 6000 cases of pneumonia in clozapine-treated patients in the context of the literature: focus on high lethality and the association with aspiration pneumonia

BACKGROUND

The literature associates clozapine with pneumonia/aspiration pneumonia.

RESEARCH DESIGN AND METHODS

The international pharmacovigilance database (VigiBase™) uses the information component (IC) as statistical signal. VigiBase clozapine reports were analyzed for pneumonia/aspiration pneumonia from introduction to 10 May 2023.

RESULTS

There were 6392 cases of all types of pneumonia (5572 cases of pneumonia, 775 of aspiration pneumonia, and 45 combined). The IC was 3.52 for aspiration pneumonia, introduced as a VigiBase label in 2003, and 1.91 for pneumonia. Patients were reclassified as 3628 with no signs of aspiration and 1533 with signs. Signs of aspiration were strongly associated with some co-medications: olanzapine, odds ratio (OR) = 23.8, 95% confidence interval (CI), 14.9-38.0; risperidone OR = 18.6, CI, 11.4-30.4; valproic acid, OR = 5.5, CI, 4.5-6.6; and benzodiazepines OR = 5.5, CI, 4.5-6.6. In 2415 cases with completed data, fatal outcomes made up 45% (signs of aspiration made no difference), but there was wide variability from 0% (females <45 years of age; duration ≤30 days) to 76% (males >64 years of age; duration >1 year). During the first week, pneumonia was associated with 1) very high titration doses, 2) very small doses in Parkinson's disease, and 3) Japan vs other countries.

CONCLUSIONS

In clozapine-treated patients: 1) at least 30% of pneumonia cases may be aspiration pneumonia, 2) stopping some co-medications may decrease the risk of aspiration pneumonia, 3) average lethality in pneumonia was 45% but may be around 75% in geriatric patients with long-term treatment, and 4) safer titrations may sometimes require 5-mg tablets.

Group arts therapies for patients with schizophrenia: a protocol of systematic review and meta-analysis

INTRODUCTION

Schizophrenia, a chronic mental problem, significantly impacts cognition, emotion and social functioning. Conventional pharmacotherapy faces challenges including numerous side effects, low adherence to medication and substantial costs. In this context, group arts therapies (GATs) emerge as a promising complementary approach for symptom alleviation in schizophrenia patients. Nonetheless, the effectiveness and safety of GATs are yet to be firmly established. This study aims to systematically assess the therapeutic impact of all group-based artistic interventions as complementary treatments for schizophrenia, focusing on their potential benefits.

METHODS AND ANALYSIS

This study will search four English-language databases (PubMed, Web of Science, Cochrane Library and Embase), two Chinese databases (Wanfang Data and China National Knowledge Infrastructure) and three Korean databases (RISS, Korean Citation Index and DBpia) from their inception until October 2023. It will include all randomised controlled trials that compare GATs for schizophrenia with standard rehabilitation methods. The primary outcome is the improvement in patients' positive and negative symptoms. Methodologies such as bias risk assessment, data synthesis, sensitivity analysis and subgroup analysis will be implemented using Review Manager V.5.4. Study results with high heterogeneity will be merged using a random-effects model (I 2>50% or p<0.1). In cases where meta-analysis is not viable due to significant clinical and methodological heterogeneity, a qualitative summary of the findings will be provided.

ETHICS AND DISSEMINATION

The data used in this systematic review are anonymised, devoid of any private information, eliminating the requirement for ethical approval. Dissemination of the research findings will be conducted via peer-reviewed publications.

PROSPERO REGISTRATION NUMBER

CRD42023471583.

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.

The introduction of clozapine at the Nathan Kline Institute in New York and its long-term consequences

Nathan S. Kline was a pioneer in psychopharmacology in the United States (US). In 1952, Kline started a research unit at Rockland State Hospital, New York. Kline brought clozapine from Switzerland since it was not yet available in the US. At Rockland State Hospital, George Simpson had conducted antipsychotic trials and had developed scales to assess movement disorders. In 1974, Simpson published the first US clozapine trial. In 1978, he published on 1) the effect of clozapine on tardive dyskinesia and 2) high plasma clozapine concentrations in two patients with seizures. His experience of clozapine withdrawal symptoms in his first 2 trials led in the future to more articles in this area. In Philadelphia, Simpson designed a double-blind randomized clinical trial (RCT) with 3 doses (100, 300 and 600 mg/day) which was published in 1999. From the 50 patients started on the RCT, 47 provided repeated plasma clozapine concentrations every other week of the RCT. This rich database of plasma clozapine concentrations under controlled conditions has contributed to many of the advances in clozapine pharmacokinetics in the last 5 years including: 1) obesity can be associated with clozapine poor metabolism (PM) status, 2) a clozapine ultrarapid metabolizer (UM) with a minimum therapeutic dose of 1591 mg/day, 3) a case of clozapine intoxication dropped from the RCT due to pneumonia, 4) cases of increased plasma concentrations during clozapine-induced fever, 5) the possibility that African-Americans may need higher clozapine doses than those of European ancestry, and 6) three indices of non-adherence.

Promoting safer and wider worldwide use of clozapine

This issue focuses on the past, the present and the future of clozapine. Of the 43 clozapine articles, nine are historical articles dealing with the past, 29 deal with the present and five with laboratory assays which may influence its future use. These 43 articles include 219 different authors from 56 countries/regions and five continents.

Prevalence and predictors of QTc prolongation in patients seen in a clozapine clinic in a real-world setting in Australia

BACKGROUND

Many antipsychotic drugs have been associated with QTc prolongation, which is a risk factor for sudden death. We studied the prevalence and predictors of QTc prolongation in treatment-resistant schizophrenia patients who were receiving clozapine in a real-world setting.

METHODS

Data were extracted from the records of all schizophrenia patients aged 18-65 years, enrolled in a clozapine clinic in metropolitan Australia during October 2020 to April 2022, for whom ECG data were available.

RESULTS

There were 104 eligible patients. The mean age of the sample was 42 years. The sample was 56 % male. About a third of patients were receiving antipsychotic and antidepressant drugs in addition to clozapine. The mean (standard deviation) QTc was 437.0 (24.8) ms in men and 445.8 (28.5) ms in women. QTc prolongation was present in 36.5 % of the sample. In univariate analysis, higher heart rate and higher clozapine levels were significantly associated with QTc prolongation; in multivariable logistic regression analysis, nonsignificant statistical trends were observed for male sex, higher heart rate, and higher serum clozapine level.

CONCLUSIONS

QTc prolongation may be common in schizophrenia patients who receive clozapine in real world settings; this is a matter of much concern. Potential predictors of QTc prolongation need to be identified and these predictors and their interactions require to be explored in studies with greater statistical power.

Can Slow Personalized Titration Using C-Reactive Protein Monitoring Decrease the High Rates and Mortality of Clozapine-Associated Myocarditis Seen in Some Countries? A Call for Research

PURPOSE/BACKGROUND

The hypothesis that slower personalized titration may prevent clozapine-associated myocarditis and decrease the disproportion incidence of 3% found in Australia was not described in a recent Australian article in this journal.

METHODS

Six countries in addition to Australia have published information suggesting a similar incidence of clozapine-associated myocarditis. On September 19, 2023, PubMed searches were updated for articles from the United States, Korea, Japan, Canada, New Zealand, and Turkey.

FINDINGS/RESULTS

An incidence of 3.5% (4/76) was found in a US hospital, but US experts were the first to propose that clozapine-associated myocarditis may be a hypersensitivity reaction associated with rapid titration and possibly preventable. Koreans and Japanese are of Asian ancestry and need lower minimum therapeutic doses for clozapine than patients of European ancestry. A 0.1% (2/1408) incidence of myocarditis during clozapine titration was found in a Korean hospital, but pneumonia incidence was 3.7% (52/1408). In 7 Japanese hospitals, 34% (37/110) of cases of clozapine-associated inflammation were found during faster titrations (based on the official Japanese titration) versus 13% (17/131) during slower titrations (based on the international titration guideline for average Asian patients). Recent limited studies from Canada, New Zealand, and Turkey suggest that slower personalized titration considering ancestry may help prevent clozapine-associated myocarditis.

IMPLICATIONS/CONCLUSIONS

Other countries have very limited published data on clozapine-associated myocarditis. Based on a recent Australian case series and these non-Australian studies, the author proposes that Australia (and other countries) should use slow personalized titration for clozapine based on ancestry and c-reactive protein monitoring.

Comprehensive dissection of prevalence rates, sex differences, and blood level-dependencies of clozapine-associated adverse drug reactions

Clozapine is often underused due to concerns about adverse drug reactions (ADRs) but studies into their prevalences are inconclusive. We therefore comprehensively examined prevalences of clozapine-associated ADRs in individuals with schizophrenia and demographic and clinical factors associated with their occurrence. Data from a multi-center study (n = 698 participants) were collected. The mean number of ADRs during clozapine treatment was 4.8, with 2.4 % of participants reporting no ADRs. The most common ADRs were hypersalivation (74.6 %), weight gain (69.3 %), and increased sleep necessity (65.9 %), all of which were more common in younger participants. Participants with lower BMI prior to treatment were more likely to experience significant weight gain (>10 %). Constipation occurred more frequently with higher clozapine blood levels and doses. There were no differences in ADR prevalence rates between participants receiving clozapine monotherapy and polytherapy. These findings emphasize the high prevalence of clozapine-associated ADRs and highlight several demographic and clinical factors contributing to their occurrence. By understanding these factors, clinicians can better anticipate and manage clozapine-associated ADRs, leading to improved treatment outcomes and patient well-being.

Clozapine-Associated Agranulocytosis: A Systematic Review. Is It Really So Frighteningly Common?

BACKGROUND

Clozapine is a very effective therapeutic option for schizophrenic disorders that have been refractory to most other therapies. This extremely positive aspect clashes easily with an adverse effect of the drug that is deemed to be a very dangerous one: agranulocytosis. We asked whether the mandatory strict hematological follow-up prescribed in the black box warning of clozapine's label is proportioned to the actual incidence of agranulocytosis, considering that is the main reason that such a drug is often used only late in the treatment course.

METHODS

We carried out a systematic review of reports examining clozapine administration and agranulocytosis incidence. We specifically selected those where mild and moderate neutropenia was not used as a trigger to stop administration of clozapine, to better estimate the sheer incidence of agranulocytosis when clozapine was continued even with mild hematological effect, where detected. We used PubMed, MEDLINE, EMBASE, Cochrane, and ScienceDirect databases to identify clinical studies conducted between January 1975 and April 2023.

RESULTS

We included 14 studies, mostly retrospective ones, that examined the incidence of hematological adverse effects in patients using clozapine. A total of 2354 subjects were included. The mean age of the subjects was 33.5 years. The mean duration of observation of subjects who took clozapine was 800 days, with a mean daily dose of 319.5 mg per day. Of the 2354 subjects examined, we found that 11 of them experienced agranulocytosis (0.47%).

CONCLUSIONS

These results suggest the evidence of a lower incidence of agranulocytosis than previously estimated and are in line with more recent meta-analyses. We may therefore think that clinical practice may demand a revision of the approach that both psychiatrists and supervising organizations often take when talking about clozapine.