Data From the World Health Organization's Pharmacovigilance Database Supports the Prominent Role of Pneumonia in Mortality Associated With Clozapine Adverse Drug Reactions

A Pharmacovigilance Study on Clozapine in the Food and Drug Administration Adverse Event Reporting System: A Regional Comparative Analysis

Objective

This pharmacovigilance study evaluated the profile of clozapine-related adverse events by region using the Food and Drug Administration Adverse Event Reporting System (FAERS).

Methods

We categorized each case into five regions (America, Europe/West Asia, Oceania, Asia, and Africa) based on the reporting country information in the FAERS database. The number of clozapine-related adverse events reported in each region was aggregated according to the preferred term (PT) and the Standardized Medical Dictionary for Regulatory Activities (MedDRA) Query (SMQ).

Results

A total of 101,872 clozapine-related adverse events were registered in the FAERS database. In America and Europe, leukocyte or neutrophil count abnormalities accounted for half of the top 10 PTs by relative reporting rate. However, Asia had higher relative reporting rates of pyrexia and salivary hypersecretion (13.91% and 10.85%, respectively). Regarding the SMQ, the relative reporting rates of infective pneumonia, convulsions, extrapyramidal syndrome, gastrointestinal obstruction, and hyperglycaemia/new onset diabetes mellitus were higher in Asia than in other regions (5.26%, 9.72%, 12.65%, 5.13%, and 8.26%, respectively), with significant differences even after adjusting for confounding factors using multivariate logistic regression analysis.

Conclusion

Spontaneous reports of adverse events associated with clozapine show regional disparities, particularly in Asia, where concentration-dependent adverse events are more frequently reported. However, the spontaneous reporting system has several limitations, requiring further research for validation.

Impacts of exposure to and subsequent discontinuation of clozapine on tripartite synaptic transmission

BACKGROUND AND PURPOSE

Clozapine is an effective antipsychotic for treatment-resistant schizophrenia, but its discontinuation leads to discontinuation syndrome/catatonia complicated by benzodiazepine-resistance and rhabdomyolysis.

EXPERIMENTAL APPROACH

This study determined time-dependent effects of exposure and subsequent discontinuation of clozapine on expression of connexin43, 5-HT receptors, intracellular L-β-aminoisobutyrate (L-BAIBA) and 2nd-messengers and signalling of AMPK, PP2A and Akt in cultured astrocytes and rat frontal cortex.

KEY RESULTS

Intracellular L-BAIBA levels increased during clozapine exposure but immediately recovered after discontinuation. Both exposure to clozapine and L-BAIBA increased connexin43 and signalling of AMPK/Akt time-dependently, but reduced PP2A signalling, 5-HT receptor expression and IP3 level. These changes recovered within 2 weeks after discontinuation, while 5-HT receptors and IP3 transiently increased during the recovery process. L-BAIBA activated AMPK signalling, leading to attenuated PP2A signalling. Astroglial D-serine release was increased by clozapine exposure but continued to increase within 1 week after discontinuation via activation of IP3 receptor function.

CONCLUSION AND IMPLICATIONS

Clozapine discontinuation restored PP2A signalling due to decreased L-BAIBA, increased 5-HT receptor expression via probably enhanced 5-HT receptor recycling, but increased astroglial D-serine release persisted by transiently activated IP3 receptors via transiently increased IP3 level. Decreased L-BAIBA caused by clozapine discontinuation is, at least partially, involved in the transiently increased 5-HT receptor and astroglial D-serine release.

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.

Overcoming the barriers to identifying and managing treatment-resistant schizophrenia and to improving access to clozapine: A narrative review and recommendation for clinical practice

Clozapine is the only approved antipsychotic for treatment-resistant schizophrenia (TRS). Although a large body of evidence supports its efficacy and favorable risk-benefit ratio in individuals who have failed two or more antipsychotics, clozapine remains underused. However, variations in clozapine utilization across geographic and clinical settings suggest that it could be possible to improve its use. In this narrative review and expert opinion, we summarized information available in the literature on the mechanisms of action, effectiveness, and potential adverse events of clozapine. We identified barriers leading to discouragement in clozapine prescription internationally, and we proposed practical solutions to overcome each barrier. One of the main obstacles identified to the use of clozapine is the lack of appropriate training for physicians: we highlighted the need to develop specific professional programs to train clinicians, both practicing and in residency, on the relevance and efficacy of clozapine in TRS treatment, initiation, maintenance, and management of potential adverse events. This approach would facilitate physicians to identify eligible patients and offer clozapine as a treatment option in the early stage of the disease. We also noted that increasing awareness of the benefits of clozapine among healthcare professionals, people with TRS, and their caregivers can help promote the use of clozapine. Educational material, such as leaflets or videos, could be developed and distributed to achieve this goal. The information provided in this article may be useful to improve disease burden and support healthcare professionals, patients, and caregivers navigating the complex pathways to TRS management.

Pneumonia Risk, Antipsychotic Dosing, and Anticholinergic Burden in Schizophrenia

Importance

Antipsychotic drugs (particularly clozapine) have been associated with pneumonia in observational studies. Despite studies of the associations between antipsychotic use and incident pneumonia, it remains unclear to what degree antipsychotic use is associated with increased risk of pneumonia, whether dose-response associations exist, and what agents are specifically associated with incident pneumonia.

Objective

To estimate pneumonia risk associated with specific antipsychotics and examine whether polytherapy, dosing, and receptor binding properties are associated with pneumonia in patients with schizophrenia.

Design, Setting, and Participants

This cohort study identified patients with schizophrenia or schizoaffective disorder (hereafter, schizophrenia) aged 16 years or older from nationwide Finnish registers from 1972 to 2014. Data on diagnoses, inpatient care, and specialized outpatient care were obtained from the Hospital Discharge Register. Information on outpatient medication dispensing was obtained from the Prescription Register. Study follow-up was from 1996 to 2017. Data were analyzed from November 4, 2022, to December 5, 2023.

Exposures

Use of specific antipsychotic monotherapies; antipsychotics modeled by dosage as low (<0.6 of the World Health Organization defined daily dose [DDD] per day), medium (0.6 to <1.1 DDDs per day), or high dose (≥1.1 DDDs per day); antipsychotic polypharmacy; and antipsychotics categorized according to their anticholinergic burden as low, medium, and high.

Main Outcomes and Measures

The primary outcome was hospitalization for incident pneumonia. Pneumonia risk was analyzed using adjusted, within-individual Cox proportional hazards regression models, with no antipsychotic use as the reference.

Results

The study included 61 889 persons with schizophrenia (mean [SD] age, 46.2 [16.0] years; 31 104 men [50.3%]). During 22 years of follow-up, 8917 patients (14.4%) had 1 or more hospitalizations for pneumonia and 1137 (12.8%) died within 30 days of admission. Compared with no antipsychotic use, any antipsychotic use overall was not associated with pneumonia (adjusted hazard ratio [AHR], 1.12; 95% CI, 0.99-1.26). Monotherapy use was associated with increased pneumonia risk compared with no antipsychotic use (AHR, 1.15 [95% CI, 1.02-1.30]; P = .03) in a dose-dependent manner, but polytherapy use was not. When categorized by anticholinergic burden, only the use of antipsychotics with a high anticholinergic burden was associated with pneumonia (AHR, 1.26 [95% CI, 1.10-1.45]; P < .001). Of specific drugs, high-dose quetiapine (AHR, 1.78 [95% CI, 1.22-2.60]; P = .003), high- and medium-dose clozapine (AHR, 1.44 [95% CI, 1.22-1.71]; P < .001 and AHR, 1.43 [95% CI, 1.18-1.74]; P < .001, respectively), and high-dose olanzapine (AHR, 1.29 [95% CI, 1.05-1.58]; P = .02) were associated with increased pneumonia risk.

Conclusions and Relevance

Results of this cohort study suggest that in patients with schizophrenia, antipsychotic agents associated with pneumonia include not only clozapine (at dosages ≥180 mg/d) but also quetiapine (≥440 mg/d) and olanzapine (≥11 mg/d). Moreover, monotherapy antipsychotics and antipsychotics with high anticholinergic burden are associated with increased pneumonia risk in a dose-dependent manner. These findings call for prevention strategies aimed at patients with schizophrenia requiring high-risk antipsychotics.

Comparative effectiveness of clozapine and non-clozapine atypical antipsychotics provided by the Brazilian National Health System in adults with schizophrenia

Introduction

Currently, 21 million people live with the disease, mostly in low to middle-income countries. We aimed to assess the survival of patients with schizophrenia using clozapine compared with non-clozapine atypical antipsychotics provided by the Brazilian National Health System using real-world data.

Materials and methods

This is an open retrospective cohort study of patients diagnosed with schizophrenia to whom atypical antipsychotics were dispensed by the Brazilian National Health System between 2000 and 2015, based on deterministic-probabilistic pairing of administrative data records. The Kaplan-Meier method was used to estimate the cumulative probability of survival and the Cox proportional hazards model was adjusted to assess the risk factors for survival via the hazard ratio (HR).

Result

Participants were 375,352 adults with schizophrenia, with an overall survival rate of 76.0% (95%CI 75.0-76.0) at the end of the cohort. Multivariate analysis indicated a greater risk of death for men (HR=1.30; 95%CI 1.27-1.32), older adults (HR=17.05; 95%CI 16.52-17.60), and in the Southeast region of Brazil (HR=1.20; 95%CI 1.17-1.23). Patients who used non-clozapine atypical antipsychotics had a 21% greater risk of death when compared to those taking clozapine (HR=1.21; 95%CI 1.14-1.29). Additionally, a history of hospitalization for pneumonia (HR=2.17; 95%CI 2.11-2.23) was the main clinical variable associated with increased risk of death, followed by hospitalization for lung cancer (HR=1.82; 95%CI 1.58-2.08), cardiovascular diseases (HR=1.44; 95%CI 1.40-1.49) and any type of neoplasia (HR=1.29; 95%CI 1.19-1.40).

Discussion

This is the first published Brazilian cohort study that evaluated survival in people with schizophrenia, highlighting the impact of atypical antipsychotics. In this real-world analysis, the use of clozapine had a protective effect on survival when compared to olanzapine, risperidone, quetiapine, and ziprasidone.

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.

Slower clozapine titration than the official Japanese protocol led to fewer inflammatory adverse effects: A retrospective chart review of seven hospitals

BACKGROUND

Higher frequencies of inflammatory adverse effects of clozapine have been reported in Japan. As the international titration protocol for Asians has set slower dose titration than the Japanese package insert, we hypothesized that a dose titration speed slower than the recommendation of the guideline would be associated with fewer inflammatory-related adverse events.

METHODS

The medical records of all 272 patients who were first started on clozapine at seven hospitals between 2009 and 2023 were studied retrospectively. Of those, 241 were included in the analysis. The patients were divided into two groups regarding whether the titration speed was faster or slower than the guideline for Asians. The incidence of inflammatory adverse events with clozapine was compared between the groups.

RESULTS

The frequency of inflammatory adverse events was 34 % (37/110) in the faster titration group and 13 % (17/131) in the slower titration group, and a significant difference was observed by Fisher exact test (odds ratio 3.38; 95 % confidence interval 1.71-6.91; p < 0.001). Serious adverse effects, fever for more than five days, and clozapine discontinuation were significantly more frequent in the faster titration group. Logistic regression analysis indicated significantly more inflammatory adverse events in the faster titration group (adjusted odds ratio 4.01; 95 % confidence interval 2.02-7.87; p < 0.001) considering age, sex, body mass index, concomitant valproic acid, and smoking as confounding factors.

CONCLUSION

Clozapine-induced inflammatory adverse events were less frequent in Japanese individuals when a titration rate was more gradual than the protocol recommended in the Japanese package insert.

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

BACKGROUND

Pharmacovigilance findings and box warnings in the clozapine package inserts have marked the history of clozapine.

OBJECTIVE

This is the largest review of clozapine adverse drug reactions (ADRs) and their associated fatal outcomes. Reports to the World Health Organization's global pharmacovigilance database, VigiBase™, were analyzed, extending from clozapine's introduction to December 31, 2022.

METHODS

The analysis focused on the top four reporting countries: United States (US), United Kingdom (UK), Canada and Australia (83 % of fatal outcomes worldwide). Attempts were made to control for population and clozapine prescription in each country.

RESULTS

Clozapine ADRs worldwide accounted for 191,557 reports, with the highest number (53,505) in "blood and lymphatic system disorder". Of the 22,596 fatal outcomes reported in clozapine patients, 9587 were from the US, 6567 from the UK, 3623 from Canada and 1484 from Australia. The top category worldwide in fatal outcomes was nonspecifically labeled "death" with 46 % (range 22-62 %). "Pneumonia" was second with 30 % (range 17-45 %). Agranulocytosis was numerically only the 35th top clozapine ADR associated with fatal outcomes. On average, 2.3 clozapine ADRs were reported per fatal outcome. Infections were associated with 24.2 % of the UK fatal outcomes (9.4 %-11.9 % in the 3 other countries).

CONCLUSIONS

The four countries appeared to report clozapine ADRs in different ways, making comparisons difficult. We estimated higher fatal outcomes in the UK and Canada after controlling for cross-sectional estimations of population and published clozapine use. This last hypothesis is limited by the lack of precise estimation of accumulated clozapine use in each country.

A brief history of clozapine in China with a look forward

Clozapine was first manufactured in China in 1976. Clozapine is currently used not only for treatment-refractory schizophrenia (TRS), but also continues to be used in the treatment of patients with non-TRS and other mental disorders; moreover, low-dose clozapine is also used in sedative-hypnotic therapy and in combination with other drugs. There is need for studies in China using various titrations and assessing their risk for myocarditis and aspiration pneumonia. The Chinese clozapine package insert will also greatly benefit from these changes.

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.

Paralytic ileus in a patient on clozapine therapy showing an inverted clozapine/norclozapine ratio after switching valproic acid to carbamazepine: a case report

This case report examines the possible correlation between the clozapine/norclozapine ratio and the occurrence of constipation and paralytic ileus. We present the case of a 42-year-old patient diagnosed with schizoaffective disorder undergoing clozapine therapy. Despite intensive treatment with clozapine, haloperidol, valproic acid and biweekly electroconvulsive therapy sessions for over a year, florid psychotic symptoms and fluctuating mood swings persisted. Therefore, valproic acid was replaced by carbamazepine, a potent inducer of several CYP450-enzymes. To maintain clozapine plasma levels, fluvoxamine, a CYP1A2-inhibitor, was introduced at a dose of 25 mg before this switch. After addition of carbamazepine, there was a significant decline in clozapine levels, necessitating an increase in fluvoxamine dosage to 50 mg. Five weeks later the patient was admitted to a general hospital with a diagnosis of paralytic ileus. Treatment with enemas proved effective. Drug concentration analysis revealed a 2.5-fold increase in norclozapine levels in the weeks preceding hospital admission, resulting in an inverted clozapine/norclozapine ratio. Treatment with clozapine, carbamazepine and fluvoxamine was continued as the patient demonstrated clinical improvement on carbamazepine. Concurrently, an intensive laxative regimen was initiated. Two weeks later, the patient was readmitted to the general hospital due to suspected paralytic ileus and faecal vomiting, once again displaying an inverted clozapine/norclozapine ratio. We discuss potential mechanisms contributing to the occurrence of the paralytic ileus in this patient, including the antagonism of muscarinic M3 receptors by both clozapine and norclozapine, as well as the agonism of delta-opioid receptors by norclozapine. This case highlights the potential significance of both the clozapine/norclozapine ratio and absolute norclozapine levels as risk factors for constipation and paralytic ileus in patients on clozapine therapy.

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.

Changes in immunoglobulin levels during clozapine treatment in schizophrenia

BACKGROUND AND HYPOTHESIS

Use of clozapine in treatment-resistant schizophrenia is often limited due to risk of adverse effects. Cross-sectional associations between clozapine treatment and low immunoglobulin levels have been reported, however prospective studies are required to establish temporal relationships. We tested the hypothesis that reductions in immunoglobulin levels would occur over the first 6 months following initiation of clozapine treatment. Relationships between immunoglobulin levels and symptom severity over the course of clozapine treatment were also explored.

DESIGN

This prospective observational study measured immunoglobulin (Ig) levels (A, M and G) in 56 patients with treatment-resistant schizophrenia at 6-, 12- and 24-weeks following initiation with clozapine. Clinical symptoms were also measured at 12 weeks using the positive and negative syndrome scale (PANSS).

RESULTS

IgA, IgG and IgM all decreased during clozapine treatment. For IgA and IgG the reduction was significant at 24 weeks (IgA: β = -32.66, 95% CI = -62.38, -2.93, p = 0.03; IgG: β = -63.96, 95% CI = -118.00, -9.31, p = 0.02). For IgM the reduction was significant at 12 and 24 weeks (12 weeks: β = -23.48, 95% CI = -39.56, -7.42, p = 0.004; 24 weeks: β = -33.12, 95 %CI = -50.30, -15.94, p = <0.001). Reductions in IgA and IgG during clozapine treatment were correlated with reductions in PANSS-total over 12 weeks (n = 32, IgA r = 0.59, p = 0.005; IgG r = 0.48, p = 0.03).

CONCLUSIONS

The observed reductions in immunoglobulin levels over six months of clozapine treatment add further evidence linking clozapine to secondary antibody deficiency. Associations between Ig reduction and symptom improvement may however indicate that immune mechanisms contribute to both desirable and undesirable effects of clozapine.

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.

Infections associated with clozapine: a pharmacovigilance study using VigiBase®

Introduction: Clozapine is primarily reserved for treatment-resistant schizophrenia due to safety concerns associated with its use. Infections have been reported with clozapine, which may lead to elevated serum levels of the drug. However, the existing literature on this topic is limited. Therefore, we conducted a study using VigiBase® to investigate the potential over-reporting of infections associated with clozapine, to explore the presence of dose-dependency, and to investigate the underlying mechanism. Methods: Disproportionality analyses were performed using VigiBase to assess the association between clozapine and all types of infections, the association between clozapine-associated infections and neutropenia, the association between clozapine-associated infections and agranulocytosis, the dose-effect relationship between clozapine and infections, and the interaction between clozapine and the main strong CYP450 inhibitors using reports carried out until 11 April 2023. Results: A statistically significant signal of infections was observed with clozapine, as indicated by an information component of 0.43 [95% CI: (0.41-0.45)]. The most commonly reported infections were respiratory and gastrointestinal in nature. Neutropenia showed weaker association with clozapine-associated reports of infections compared to other clozapine-associated reports [X2 (1, N = 204,073) = 454; p < 0.005], while agranulocytosis demonstrated a stronger association with clozapine-associated reports of infections [X2 (1, N = 204,073) = 56; p < 0.005]. No evidence of dose-dependency was observed. Among the 17 tested CYP inhibitors, significant drug-drug interactions were found with clarithromycin, metronidazole, valproic acid, lansoprazole, omeprazole, amiodarone, and esomeprazole. Discussion: Our study revealed a significant safety signal between clozapine use and infections, predominantly respiratory and gastrointestinal infections. The co-administration of clozapine with valproic acid or proton pump inhibitors may potentially contribute to an increased risk of infection. Further vigilance is warranted in clinical practice, and consideration of therapeutic drug monitoring of clozapine in cases involving concomitant use of these drugs or in the presence of infections may be beneficial.

[Safety aspects during treatment with clozapine: : Adverse effects, titration, and therapeutic drug monitoring - a narrative review]

BACKGROUND

According to current guidelines, clozapine should be used as a third step in treatment resistant schizophrenia (TRS). In everyday clinical practice, however, it is frequently used at a much later stage, which leads to a significant deterioration of prognosis. The first part of this narrative overview focuses on the most frequent side effects of clozapine, on the relevance of slow titration, and on specific aspects of therapeutic drug monitoring (TDM).

MATERIAL AND METHODS

Medline, the Guideline for the use of clozapine 2013 of the Netherlands Clozapine Collaboration Group, and the S3 Guideline for Schizophrenia of the German Association for Psychiatry, Psychotherapy and Psychosomatics were searched for relevant literature, the last query dating from April 28th, 2023.

RESULTS

Despite its unique efficacy clozapine is underused in clinical practice and prescription varies between and within countries. Next to hematological, metabolic, and vegetative side effects, clozapine induced inflammation manifesting in the form of pneumonia or myocarditis, which is mainly associated with rapid titration, represents a major clinical challenge with CRP monitoring being of particular relevance. In this context, it also has to be noted that sex, smoking behavior, and ethnic origin impact clozapine metabolism, thus requiring personalized dosing.

CONCLUSION

Slow titration when possible, TDM, and CYP diagnostics when appropriate increase patient safety during treatment with clozapine and thus the likelihood of early prescription of this compound in TRS.

COVID-19 pandemic in the intensive care unit: Psychological implications and interventions, a systematic review

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic produced changes in intensive care units (ICUs) in patient care and health organizations. The pandemic event increased patients’ risk of developing psychological symptoms during and after hospitalisation. These consequences also affected those family members who could not access the hospital. In addition, the initial lack of knowledge about the virus and its management, the climate of fear and uncertainty, the increased workload and the risk of becoming infected and being contagious, had a strong impact on healthcare staff and organizations. This highlighted the importance of interventions aimed at providing psychological support to ICUs, involving patients, their relatives, and the staff; this might involve the reorganisation of the daily routine and rearrangement of ICU staff duties.

AIM

To conduct a systematic review of psychological issues in ICUs during the COVID-19 pandemic involving patients, their relatives, and ICU staff.

METHODS

We investigated the PubMed and the ClinicalTrials.gov databases and found 65 eligible articles, upon which we commented.

RESULTS

Our results point to increased perceived stress and psychological distress in staff, patients and their relatives and increased worry for being infected with severe acute respiratory syndrome coronavirus-2 in patients and relatives. Furthermore, promising results were obtained for some psychological programmes aiming at improving psychological measures in all ICU categories.

CONCLUSION

As the pandemic limited direct inter-individual interactions, the role of interventions using digital tools and virtual reality is becoming increasingly important. All considered, our results indicate an essential role for psychologists in ICUs.

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.

Feasibility and Effect of Increasing Clozapine Plasma Levels in Long-Stay Patients With Treatment-Resistant Schizophrenia

BACKGROUND

It is unknown whether increasing the clozapine plasma level to 400, 750, or even 1000 ng/mL is a feasible and effective strategy in patients with treatment-resistant schizophrenia (TRS). We investigated this in long-stay patients with TRS.

METHODS

In long-stay TRS patients, doses of clozapine were increased gradually to reach target plasma levels of 400, 750, or 1000 ng/mL, depending on the clinical response and tolerability. After an effective or tolerated level was reached, positive and negative syndrome scale scores were evaluated after 3 months and 1 year.

RESULTS

Twenty-eight patients were included. Overall, 54% of the patients, and especially patients 60 years and older, could not achieve one of the clozapine target levels because of adverse effects. Three physically vulnerable patients died, probably not directly related to clozapine use. Although only 21% of patients achieved a more than 20% reduction in total symptoms at the 1-year follow-up, the mean severity of positive symptoms decreased from 18.18 to 15.10 ( P < 0.01). The largest decrease in positive symptoms was seen in TRS patients who achieved a plasma level of 750 ng/mL of clozapine.

CONCLUSIONS

Most TRS patients older than 60 years could not tolerate high clozapine levels and so this should not be attempted in older or otherwise physically vulnerable patients. Increasing clozapine levels to approximately 750 ng/mL in middle-aged patients with longstanding TRS may modestly reduce the severity of positive symptoms and improve the response rate.

Development and validation of a risk prediction nomogram for disposition of acute clozapine intoxicated patients to intensive care unit

BACKGROUND

Clozapine is an atypical antipsychotic drug used for the treatment of refractory schizophrenia. It is reported as the most toxic in its class. Using serum clozapine level as a severity indicator is doubtful and unfeasible, particularly in low resourced countries.

METHODS

This is an extended two-phase retrospective study that utilized medical records of patients diagnosed with acute clozapine intoxication and admitted to Tanta University Poison Control Center, Egypt during the past 6 years. Two hundred and eight medical records were used to establish and validate a nomogram for predicting the need for intensive care unit (ICU) admission in acute clozapine intoxicated patients.

RESULTS

A reliable simple bedside nomogram was developed and proved its significant ability to predict the need for ICU admission, with an area under the curve (AUC) of 83.9% and 80.8% accuracy. It encompassed the age of admitted patients (AUC = 64.8%, p = .003), respiratory rate (AUC = 74.7%, p < .001), O₂ saturation (AUC = 71.7%, p < .001), and random blood glucose level upon admission (AUC = 70.5%, p < .001). External validation of the proposed nomogram showed a high AUC (99.2%) with an overall accuracy of 96.2%.

CONCLUSION

There is a need to develop a reliable objective tool predicting the severity and need for ICU admission in acute clozapine intoxication. The proposed nomogram is a substantially valuable tool to estimate ICU admission probabilities among patients with acute clozapine intoxication and will help clinical toxicologists make rapid decisions for ICU admission, especially in countries with low resources.

Clozapine-associated myocarditis in the World Health Organization's pharmacovigilance database: Focus on reports from various countries

INTRODUCTION

The incidence of clozapine-associated myocarditis varies by country. These variations were explored in VigiBase, the World Health Organization's global database which has >25 million spontaneously reported adverse drug reaction (ADR) reports from 145 national drug agencies.

METHODS

On January 15, 2021, a search of VigiBase since inception focused on myocarditis in clozapine patients. The 3572 individual reports were studied using the standard VigiBase logarithmic measure of disproportionality called information component (IC). The IC measures the disproportionality between the expected and the reported rates. After duplicates were eliminated there were 3274 different patients with myocarditis studied in logistic regression models.

RESULTS

The first case was published in 1980 but since 1993 the VigiBase clozapine-myocarditis IC has been significant; moreover, currently it is very strong (IC=6.0, IC₀₀₅-IC₉₉₅=5.9-6.1) and statistically significantly different from other antipsychotics. Of the 3274 different patients with myocarditis, 43.4% were non-serious cases, 51.8% were serious but non-fatal, and 4.8% were fatal. More than half (1621/3274) of the reports came from Australia, of which 69.2% were non-serious, 27.7% serious but non-fatal, and 3.1% fatal. Asian countries contributed only 41 cases.

CONCLUSIONS

In pharmacovigilance studies, confounding factors may explain statistical associations, but the strength and robustness of these results are compatible with the hypothesis that myocarditis is definitively associated with early clozapine treatment (84% [1309/1560] and 5% [82/1560] in the first and second months). Myocarditis reports from Australia are over-represented to a major degree. Asian countries may be underreporting myocarditis to their drug agencies.

Respiratory aspiration during treatment with benzodiazepines, antiepileptic and antidepressant drugs in the pharmacovigilance database from VigiBase

INTRODUCTION

Three psychotropic drug classes, benzodiazepines, antiepileptic drugs (AEDs) and antidepressants (ADs), whether used in treatment or overdose, may be associated with respiratory aspiration. Polypharmacy was defined by counting suspected drugs from these classes or two others, antipsychotics and opioids. The confounding effects of polypharmacy were considered in this study.

AREAS COVERED

VigiBase records of respiratory aspiration associated with benzodiazepines, AEDs, and/or ADs 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 benzodiazepines 2.8 (and 2.6), AEDs 1.6 (and 1.5), and ADs 1.4 (and 1.3). The cases of respiratory aspiration associated with at least one drug from these 3 classes included: 1) 553 cases absent any known overdose (2.8±1.7 drugs) and 2) 347 overdose cases (2.9±1.8 drugs). Little support for the association of respiratory aspiration and benzodiazepine, AED or AD monotherapy in therapeutic dosages was found. Studies of the association between benzodiazepine monotherapy and respiration aspiration are needed in geriatric patients. ADs added to other medications increased lethality in all cases of respiratory aspiration including those associated with overdose, polypharmacy and/or major medical problems.

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

White blood cell (WBC) monitoring has reduced clozapine-treated patient deaths associated with agranulocytosis to a rarity. However, clozapine protocols and package inserts worldwide provide no instructions for preventing myocarditis or pneumonia during clozapine titrations. Prescribers worldwide are largely unaware of that. Meanwhile, as they worry about agranulocytosis, their clozapine-treated patients are at risk of dying from pneumonia or myocarditis. Consequently, an international guideline with 104 authors from 50 countries/regions was recently published to provide personalised clozapine titration schedules for adult inpatients. This forum article reviews pneumonia and myocarditis occurring during clozapine titration, as well as the three most innovative aspects of this new guideline: (1) personalised titration, (2) C reactive protein (CRP) measures, and (3) dose predictions based on blood levels. Clozapine metabolism is influenced by 3 levels of complexity: (1) ancestry groups, (2) sex-smoking subgroups, and (3) presence/absence of poor metabolizer status. These 3 groups of variables should determine the maintenance dose and speed of clozapine titration; they are summarised in a table in the full-text. The international clozapine titration guideline recommends measuring CRP levels simultaneously with WBC, at baseline and weekly at least for the first 4 weeks of titration, the highest risk period for clozapine-induced myocarditis.

Pharmacogenomics of Clozapine-induced agranulocytosis: a systematic review and meta-analysis

Although clozapine is the most effective pharmacotherapy for treatment-resistant schizophrenia, it is under-utilized, and initiation is often delayed. One reason is the occurrence of a potentially fatal adverse reaction, clozapine-induced agranulocytosis (CIA). Identifying genetic variations contributing to CIA would help predict patient risk of developing CIA and personalize treatment. Here, we (1) review existing pharmacogenomic studies of CIA, and (2) conduct meta-analyses to identify targets for clinical implementation. A systematic literature search identified studies that included individuals receiving clozapine who developed CIA and controls who did not. Results showed that individuals carrying the HLA-DRB1*04:02 allele had nearly sixfold (95% CI 2.20–15.80, p_corrected = 0.03) higher odds of CIA with a negative predictive value of 99.3%. Previously unreplicated alleles, TNFb5, HLA-B*59:01, TNFb4, and TNFd3 showed significant associations with CIA after multiple-testing corrections. Our findings suggest that a predictive HLA-DRB1*04:02-based pharmacogenomic test may be promising for clinical implementation but requires further investigation.

A Guideline and Checklist for Initiating and Managing Clozapine Treatment in Patients with Treatment-Resistant Schizophrenia

Treatment-resistant schizophrenia (TRS) will affect about one in three patients with schizophrenia. Clozapine is the only treatment approved for TRS, and patients should be treated as soon as possible to improve their chances of achieving remission. Despite its effectiveness, concern over side effects, monitoring requirements, and inexperience with prescribing often result in long delays that can expose patients to unnecessary risks and compromise their chances of achieving favorable long-term outcomes. We critically reviewed the literature on clozapine use in TRS, focusing on guidelines, systematic reviews, and algorithms to identify strategies for improving clozapine safety and tolerability. Based on this, we have provided an overview of strategies to support early initiation of clozapine in patients with TRS based on the latest evidence and our clinical experience, and have summarized the key elements in a practical, evidence-based checklist for identifying and managing patients with TRS, with the aim of increasing confidence in prescribing and monitoring clozapine therapy.

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.

Targeting α6GABAA receptors as a novel therapy for schizophrenia: A proof-of-concept preclinical study using various animal models

GABA_A receptors containing α6 subunits (α6GABA_ARs) in the cerebellum have -been implicated in schizophrenia. It was reported that the GABA synthesizing enzymes were downregulated whereas α6GABA_ARs were upregulated in postmortem cerebellar tissues of patients with schizophrenia and in a rat model induced by chronic phencyclidine (PCP). We have previously demonstrated that pyrazoloquinolinone Compound 6, an α6GABA_AR-highly selective positive allosteric modulator (PAM), can rescue the disrupted prepulse inhibition (PPI) induced by methamphetamine (METH), an animal model mimicking the sensorimotor gating deficit based on the hyper-dopaminergic hypothesis of schizophrenia. Here, we demonstrate that not only Compound 6, but also its structural analogues, LAU463 and LAU159, with similarly high α6GABA_AR selectivity and their respective deuterated derivatives (DK-I-56-1, DK-I-58-1 and DK-I-59-1) can rescue METH-induced PPI disruption. Besides, Compound 6 and DK-I-56-I can also rescue the PPI disruption induced by acute administration of PCP, an animal model based on the hypo-glutamatergic hypothesis of schizophrenia. Importantly, Compound 6 and DK-I-56-I, at doses not affecting spontaneous locomotor activity, can also rescue impairments of social interaction and novel object recognition in mice induced by chronic PCP treatments. At similar doses, Compound 6 did not induce sedation but significantly suppressed METH-induced hyperlocomotion. Thus, α6GABA_AR-selective PAMs can rescue not only disrupted PPI but also hyperlocomotion, social withdrawal, and cognitive impairment, in both METH- and PCP-induced animal models mimicking schizophrenia, suggesting that they are a potential novel therapy for the three core symptoms, i.e. positive symptoms, negative symptoms, and cognitive impairment, of schizophrenia.

The role of alcohol intake in the pharmacogenetics of treatment with clozapine

Clozapine (CLZ) is an atypical antipsychotic reserved for patients with refractory psychosis, but it is associated with a significant risk of severe adverse reactions (ADRs) that are potentiated with the concomitant use of alcohol. Additionally, pharmacogenetic studies have explored the influence of several genetic variants in CYP450, receptors and transporters involved in the interindividual response to CLZ. Herein, we systematically review the current multiomics knowledge behind the interaction between CLZ and alcohol intake, and how its concomitant use might modulate the pharmacogenetics. CYP1A2*1F, *1C and other alleles not yet discovered could support a precision medicine approach for better therapeutic effects and fewer CLZ ADRs. CLZ monitoring systems should be amended and include alcohol intake to protect patients from severe CLZ ADRs.

COVID-related hospitalization, intensive care treatment, and all-cause mortality in patients with psychosis and treated with clozapine

Clozapine, an antipsychotic, is associated with increased susceptibility to infection with COVID-19, compared to other antipsychotics. Here, we investigate associations between clozapine treatment and increased risk of adverse outcomes of COVID-19, namely COVID-related hospitalisation, intensive care treatment, and death, amongst patients taking antipsychotics with schizophrenia-spectrum disorders. Using the clinical records of South London and Maudsley NHS Foundation Trust, we identified 157 individuals who had an ICD-10 diagnosis of schizophrenia-spectrum disorders, were taking antipsychotics (clozapine or other antipsychotics) at the time of COVID-19 pandemic in the UK and had a laboratory-confirmed COVID-19 infection. The following health outcomes were measured: COVID-related hospitalisation, COVID-related intensive care treatment and death. We tested associations between clozapine treatment and each outcome using logistic regression models, adjusting for gender, age, ethnicity, neighbourhood deprivation, obesity, smoking status, diabetes, asthma, bronchitis and hypertension using propensity scores. Of the 157 individuals who developed COVID-19 while on antipsychotics (clozapine or other antipsychotics), there were 28% COVID-related hospitalisations, 8% COVID-related intensive care treatments and 8% deaths of any cause during the 28 days follow-up period. amongst those taking clozapine, there were 25% COVID-related hospitalisations, 7% COVID-related intensive care treatments and 7% deaths. In both unadjusted and adjusted analyses, we found no significant association between clozapine and any of the outcomes. Thus, we found no evidence that patients with clozapine treatment at time of COVID-19 infection had increased risk of hospitalisation, intensive care treatment or death, compared to non-clozapine antipsychotic-treated patients. However, further research should be considered in larger samples to confirm this.

Clozapine-induced gastrointestinal hypomotility: presenting features and outcomes, UK pharmacovigilance reports, 1992-2017

BACKGROUND

Clozapine-induced gastrointestinal hypomotility (CIGH) affects some 75% of patients treated with clozapine.

AIMS

To document the incidence of potentially harmful CIGH in the UK.

METHOD

We studied spontaneous UK pharmacovigilance reports recorded as clozapine-related gastrointestinal adverse drug reactions, 1992-2017.

RESULTS

There were 527 patients reported with potentially harmful CIGH; 33% (n = 172) died. Deaths averaged 1 per year 1992-1999, 5 per year 2000-2009 and 15 per year 2010-2017. Those who died were older (median 52 years v. 49 years) and had been prescribed clozapine for longer than those who recovered (median 11.3 years v. 4.8 years), but there was no difference in prescribed dose. Within the first 4 years of clozapine treatment, there were 169 reports of CIGH, of which 3% (n = 5) were fatal. At 10-14 years there were 63 reports of CIGH, of which 25% (n = 16) were fatal. Among the deaths, males were younger (median 51, range 22-89 v. median 57, range 24-89 years) with higher clozapine doses (median 450, range 100-900 v. median 300, range 12.5-800 mg/d) than females. In non-fatal CIGH, surgery was the most frequent outcome (n = 92). The procedures included appendectomy, ileostomy, total/partial colectomy, colostomy/stoma and proctosigmoidectomy. Clozapine dosage was reduced in 6 patients, stopped and restarted in 23, 'continued' in 6 and discontinued permanently in at least 76 patients.

CONCLUSIONS

The risk of serious morbidity/mortality from CIGH is substantial. The need to actively monitor bowel function and give laxatives to patients treated with clozapine is clear.

Incident infection during the first year of treatment - A comparison of clozapine and paliperidone palmitate long-acting injection

BACKGROUND

To examine the risk of infection in patients prescribed clozapine compared with patients prescribed paliperidone palmitate long-acting injection (PPLAI).

METHOD

A retrospective, 1-year, cohort study conducted on events occurring in eligible patients beginning treatment for the first time with clozapine or PPLAI between June 2017 and June 2019 in a UK mental health trust providing in-patient and out-patient services.

RESULTS

The study included 64 patients starting clozapine and 120 patients starting PPLAI. Incidence of infection was greater in clozapine starters than in PPLAI starters (28% vs 6%; p = 0.001; adjusted odds ratio 5.82 (95% confidence interval (CI) = 2.15-15.76, p = 0.001). Infectious episodes in clozapine patients were not related to changes in neutrophil counts. Incident infection in the clozapine group was highest in the first 3 months of treatment. The most commonly reported infection in the clozapine group was chest infection; however, the majority of infections were non-chest-related.

CONCLUSION

Patients starting clozapine showed a substantially increased likelihood of infection compared with patients starting PPLAI.

Clozapine treatment and risk of severe COVID-19 infection

OBJECTIVE

To investigate whether patients with clozapine treatment are at an increased risk of a more severe COVID-19 infection as compared with patients on other antipsychotic drugs.

METHODS

In this register-based cohort study, all residents (age 18 or older) in the Stockholm Region with a psychotic disorder diagnosis and antipsychotic treatment were included (N = 8 233) and followed from 1 March 2020 to 14 January 2021. The exposure was defined as clozapine treatment and the outcome measures (indicating a more severe COVID-19 infection) were: inpatient care, care within intensive care unit or death due to COVID-19 infection. Differences in outcome rates between exposed (n = 966) and unexposed (other antipsychotics; n = 7 267) were examined using Cox proportional hazards models and expressed as hazard ratios (HR) with 95% confidence intervals (CI).

RESULTS

No statistically significant differences in outcome rates were found between the two groups of patients after adjusting for age, sex and residence in retirement homes. The adjusted HR for the exposed compared to the unexposed was 0.96 (95% CI: 0.54, 1.70) for inpatient care; 1.69 (0.48, 5.93) for care in intensive care unit (ICU); and 0.86 (0.26, 2.80) for death. Regarding inpatient care, additional adjusting for country of birth, living in socioeconomically vulnerable areas, number of care visits during the previous year, and comorbid medical illnesses did not alter the results.

CONCLUSIONS

Our results may add support to the present guidelines, recommending sustained clozapine treatment during the current COVID-19 pandemic with careful monitoring and readiness to alter drug doses as needed.

An International Adult Guideline for Making Clozapine Titration Safer by Using Six Ancestry-Based Personalized Dosing Titrations, CRP, and Clozapine Levels

This international guideline proposes improving clozapine package inserts worldwide by using ancestry-based dosing and titration. Adverse drug reaction (ADR) databases suggest that clozapine is the third most toxic drug in the United States (US), and it produces four times higher worldwide pneumonia mortality than that by agranulocytosis or myocarditis. For trough steady-state clozapine serum concentrations, the therapeutic reference range is narrow, from 350 to 600 ng/mL with the potential for toxicity and ADRs as concentrations increase. Clozapine is mainly metabolized by CYP1A2 (female non-smokers, the lowest dose; male smokers, the highest dose). Poor metabolizer status through phenotypic conversion is associated with co-prescription of inhibitors (including oral contraceptives and valproate), obesity, or inflammation with C-reactive protein (CRP) elevations. The Asian population (Pakistan to Japan) or the Americas' original inhabitants have lower CYP1A2 activity and require lower clozapine doses to reach concentrations of 350 ng/mL. In the US, daily doses of 300-600 mg/day are recommended. Slow personalized titration may prevent early ADRs (including syncope, myocarditis, and pneumonia). This guideline defines six personalized titration schedules for inpatients: 1) ancestry from Asia or the original people from the Americas with lower metabolism (obesity or valproate) needing minimum therapeutic dosages of 75-150 mg/day, 2) ancestry from Asia or the original people from the Americas with average metabolism needing 175-300 mg/day, 3) European/Western Asian ancestry with lower metabolism (obesity or valproate) needing 100-200 mg/day, 4) European/Western Asian ancestry with average metabolism needing 250-400 mg/day, 5) in the US with ancestries other than from Asia or the original people from the Americas with lower clozapine metabolism (obesity or valproate) needing 150-300 mg/day, and 6) in the US with ancestries other than from Asia or the original people from the Americas with average clozapine metabolism needing 300-600 mg/day. Baseline and weekly CRP monitoring for at least four weeks is required to identify any inflammation, including inflammation secondary to clozapine rapid titration.

Effects of an Atypical Antipsychotic, Zotepine, on Astroglial L-Glutamate Release through Hemichannels: Exploring the Mechanism of Mood-Stabilising Antipsychotic Actions and Antipsychotic-Induced Convulsion

Accumulating neuropsychopharmacological evidence has suggested that functional abnormalities of astroglial transmission and protein kinase B (Akt) contribute to the pathophysiology and/or pathomechanisms of several neuropsychiatric disorders, such as epilepsy, schizophrenia, affective disorders and antipsychotic-induced convulsions. Therefore, to explore the pathophysiology of mood-stabilising antipsychotics and the proconvulsive actions of atypical antipsychotics, the present study determined the effects of a mood-stabilising, atypical, antipsychotic agent, zotepine (ZTP), on astroglial L-glutamate release and the expression of connexin43 (Cx43) protein in cortical, primary, cultured astrocytes using ultra-high-pressure liquid chromatography and capillary immunoblotting systems. Both acute and subchronic administrations of therapeutically relevant concentrations of ZTP did not affect astroglial L-glutamate release or Cx43 expression in plasma membranes; however, chronic administration of a therapeutically relevant concentration of ZTP increased astroglial L-glutamate release and Cx43 expression in the plasma membrane. Subchronic administrations of a supratherapeutic concentration of ZTP enhanced astroglial L-glutamate release and Cx43 expression in the plasma membrane, whereas acute administration of a supratherapeutic concentration of ZTP enhanced astroglial L-glutamate release without affecting Cx43 expression. These stimulatory effects of ZTP on astroglial L-glutamate release through activated hemichannels and Cx43 trafficking to the astroglial plasma membrane were suppressed by the Akt inhibitor. These results suggest that ZTP enhances astroglial L-glutamate release in a concentration-dependent and time-dependent manner due to the enhanced function of astroglial hemichannels, probably via activation of Akt signalling. Therefore, the enhanced astroglial L-glutamatergic transmission induced by ZTP is, at least partially, involved in the mood-stabilising antipsychotic and proconvulsive actions of ZTP.

Clozapine-associated myocarditis in the World Health Organization's pharmacovigilance database: Focus on reports from various countries

INTRODUCTION

The incidence of clozapine-associated myocarditis varies by country. These variations were explored in VigiBase, the World Health Organization's global database which has >25 million spontaneously reported adverse drug reaction (ADR) reports from 145 national drug agencies.

METHODS

On January 15, 2021, a search of VigiBase since inception focused on myocarditis in clozapine patients. The 3572 individual reports were studied using the standard VigiBase logarithmic measure of disproportionality called information component (IC). The IC measures the disproportionality between the expected and the reported rates. After duplicates were eliminated there were 3274 different patients with myocarditis studied in logistic regression models.

RESULTS

The first case was published in 1980 but since 1993 the VigiBase clozapine-myocarditis IC has been significant; moreover, currently it is very strong (IC=6.0, IC005-IC995=5.9-6.1) and statistically significantly different from other antipsychotics. Of the 3274 different patients with myocarditis, 43.4% were non-serious cases, 51.8% were serious but non-fatal, and 4.8% were fatal. More than half (1621/3274) of the reports came from Australia, of which 69.2% were non-serious, 27.7% serious but non-fatal, and 3.1% fatal. Asian countries contributed only 41 cases.

CONCLUSIONS

In pharmacovigilance studies, confounding factors may explain statistical associations, but the strength and robustness of these results are compatible with the hypothesis that myocarditis is definitively associated with early clozapine treatment (84% [1309/1560] and 5% [82/1560] in the first and second months). Myocarditis reports from Australia are over-represented to a major degree. Asian countries may be underreporting myocarditis to their drug agencies.

Clozapine treatment and risk of COVID-19 infection: retrospective cohort study

BACKGROUND

Clozapine, an antipsychotic with unique efficacy in treatment-resistant psychosis, is associated with increased susceptibility to infection, including pneumonia.

AIMS

To investigate associations between clozapine treatment and increased risk of COVID-19 infection in patients with schizophrenia-spectrum disorders who are receiving antipsychotic medications in a geographically defined population in London, UK.

METHOD

Using information from South London and Maudsley NHS Foundation Trust (SLAM) clinical records, via the Clinical Record Interactive Search system, we identified 6309 individuals who had an ICD-10 diagnosis of schizophrenia-spectrum disorders and were taking antipsychotics at the time of the COVID-19 pandemic onset in the UK. People who were on clozapine treatment were compared with those on any other antipsychotic treatment for risk of contracting COVID-19 between 1 March and 18 May 2020. We tested associations between clozapine treatment and COVID-19 infection, adjusting for gender, age, ethnicity, body mass index (BMI), smoking status and SLAM service use.

RESULTS

Of 6309 participants, 102 tested positive for COVID-19. Individuals who were on clozapine had increased risk of COVID-19 infection compared with those who were on other antipsychotic medication (unadjusted hazard ratio HR = 2.62, 95% CI 1.73-3.96), which was attenuated after adjusting for potential confounders, including clinical contact (adjusted HR = 1.76, 95% CI 1.14-2.72).

CONCLUSIONS

These findings provide support for the hypothesis that clozapine treatment is associated with an increased risk of COVID-19 infection. Further research will be needed in other samples to confirm this association. Potential clinical implications are discussed.

Exploring a Safety Signal of Antipsychotic-Associated Pneumonia: A Pharmacovigilance-Pharmacodynamic Study

An association between antipsychotic drugs and pneumonia has been demonstrated in several studies; however, the risk for pneumonia caused by specific antipsychotics has not been extensively studied. The underlying mechanism is still unknown, and several receptor mechanisms have been proposed. Therefore, using a combined pharmacovigilance-pharmacodynamic approach, we aimed to investigate safety signals of US Food and Drug Administration (FDA)-approved antipsychotics for reporting pneumonia and the potential receptor mechanisms involved. A disproportionality analysis was performed to detect a signal for reporting "infective-pneumonia" and "pneumonia-aspiration" and antipsychotics using reports submitted between 2004 and 2019 to the FDA adverse events spontaneous reporting system (FAERS) database. Disproportionality was estimated using the crude and the adjusted reporting odds ratio (aROR) and its 95% confidence interval (CI) in a multivariable logistic regression. Linear regressions investigated the relationship between aROR and receptor occupancy, which was estimated using in vitro receptor-binding profiles. Safety signals for reporting infective-pneumonia were identified for clozapine (LL = 95% 3.4, n = 546 [aROR: 4.8]) as well as olanzapine (LL = 95% 1.5, n = 250 [aROR: 2.1]) compared with haloperidol, while aRORs were associated with higher occupancies of muscarinic receptors (beta = .125, P-value = .016), yet other anti-muscarinic drugs were not included as potential confounders. No safety signals for reporting pneumonia-aspiration were detected for individual antipsychotics. Multiple antipsychotic use was associated with both reporting infective-pneumonia (LL 95%: 1.1, n = 369 [aROR:1.2]) and pneumonia-aspiration (LL 95%: 1.7, n = 194 [aROR: 2.0]). Considering the limitations of disproportionality analysis, further pharmacovigilance data and clinical causality assessment are needed to validate this safety signal.

An evaluation of the variation and underuse of clozapine in the United Kingdom

BACKGROUND

Clozapine is the only licensed treatment for treatment refractory schizophrenia. Despite this, it remains grossly underused relative to the prevalence of refractory schizophrenia. The extent of underuse and the degree of regional variation in prescribing in the United Kingdom is unknown. It is also unclear, how the UK compares with other European countries in rates of clozapine prescribing.

METHODS

We obtained data relating to all clozapine prescribing in the UK from the relevant clozapine registries. We examined regional variation in clozapine use across England, corrected for the known prevalence of severe mental illness (SMI). We also compared the UK rate of clozapine use per 100,000 population to that described in other European countries.

FINDINGS

There is substantial variation in clozapine prescribing across different regions of England and only about a third of potentially eligible patients were prescribed the drug in the UK. Clozapine prescribing rate in the UK was lower than in several European countries.

INTERPRETATION

There is clear regional inequity in access to the most effective treatment in refractory schizophrenia in England. Strategies to increase clozapine use, by overcoming both real and perceived barriers, are urgently necessary to reduce treatment inequity for patients with refractory schizophrenia.

European Whites May Need Lower Minimum Therapeutic Clozapine Doses Than Those Customarily Proposed

PURPOSE/BACKGROUND

A nomogram from a British naturalistic study proposed that the clozapine dosing needed to reach a serum concentration of 350 ng/mL ranged from 265 mg/d (female nonsmokers) to 525 mg/d (male smokers). Some European reviews have used these dosing recommendations, which seem greater than what we found in an Italian White sample ranging from 245 mg/d (female nonsmokers) to 299 mg/d (male smokers). Five other published samples of European Whites were added to the Italian sample to estimate clozapine doses recommended for reaching 350 ng/mL.

METHODS/PROCEDURES

Average clozapine metabolizers were obtained by eliminating outliers with confounding variables: (1) psychiatric inducers and inhibitors; (2) doses less than 100 mg/d; and (3) when possible, patients with inflammation, obesity, or using oral contraceptives. The study included 1363 average metabolizer European Whites: the Italian sample and 5 new samples. Mean averages that reached serum concentration levels of 350 ng/mL were calculated after stratification by sex and smoking status in each sample. Then, weighted mean averages were obtained by combining the 6 samples.

FINDINGS/RESULTS

The estimated weighted mean clozapine dosages ranged from 236 to 368 mg/d (236 mg/d in 218 female nonsmokers, 256 mg/d in 340 male nonsmokers, 357 mg/d in 269 female smokers, and 368 mg/d in 546 male smokers).

IMPLICATIONS/CONCLUSIONS

Our recommended dosages are less than those recommended in Europe. Future studies in European Whites need to replicate these recommended doses for average metabolizer patients after sex and smoking stratification and further explore clozapine dosing for those with relevant clinical confounders.