Reasons for discontinuing clozapine: A cohort study of patients commencing treatment

Exploring the factors and outcomes of clozapine discontinuation in India: A retrospective analysis

BACKGROUND

Clozapine is used in the management of treatment-resistant schizophrenia. Although the reported adverse effects with clozapine are more, and the risk of clozapine discontinuation is present, few Indian studies have examined the correlates of clozapine discontinuation. Furthermore, there is a lack of consensus on alternative treatment after clozapine discontinuation. This study aimed to explore these factors among patients treated in a tertiary psychiatric centre in India.

METHODS

We performed a retrospective chart review of the clozapine database from tertiary care schizophrenia clinic services (2015-2023) and identified 30 eligible case records of clozapine discontinuation. We examined the correlates of clozapine discontinuation.

RESULTS

Among patients who discontinued clozapine, 66.7 % were male, with an average age of 32.30 ± 9.78 years. The most common causes for discontinuation were adverse effects(56.67 %), inadequate therapeutic response(23.34 %), and non-adherence(13.33 %). Down-titration was used for 58.82 % (10/17 in whom discontinuation method details were available) of patients, with no withdrawal adverse effects noted. Clozapine retrial was considered among nine patients. Following clozapine discontinuation, among the interventions tried, ECT showed a significant response, followed by haloperidol and risperidone. Amisulpride, olanzapine, and flupentixol depot showed a moderate response.

CONCLUSIONS

These results align with previous studies, showing that adverse effects and inadequate response are prominent reasons for clozapine discontinuation and demonstrate the possibility of clozapine retrial in selected patients. Managing adverse effects might result in improvement, at least to a mild degree. Clozapine discontinuation can be avoided in a cohort with non-serious adverse effects, given the superiority of clozapine in resistant schizophrenia.

Clozapine-Related Tachycardia: An Analysis of Incidence

BACKGROUND AND OBJECTIVES

Sinus tachycardia commonly occurs at the start of clozapine treatment, often leading to discontinuation owing to perceived adverse cardiovascular effects. However, little evidence exists on its natural course after clozapine initiation. We aimed to determine the frequency and course of clozapine-induced tachycardia over the first month of treatment and to identify possible risk factors METHODS: In this cross-sectional study, we serially monitored heart rates (HRs) and other clinical variables of psychiatric inpatients commencing clozapine over the first 28 days. HRs were plotted over time and modelled by explanatory variables, including age group, sex, body mass index (BMI), smoking status and prescribed medications for HR.

RESULTS

In total, 123 consecutive inpatients undergoing clozapine titration were assessed daily, with 2901 HR measures collected. After starting clozapine, mean HR increased from 83.7 to 99.5 beats per minute (bpm). Almost all participants (93.5%) had at least one recorded HR > 100 bpm, and 68% had three consecutive days with HR > 100 bpm (being then defined as tachycardic). At least one HR > 120 bpm was recorded in 35.8%, and 8% had persistent HRs > 120 bpm. Tachycardia occurred early during clozapine titration, with a dose response effect at lower doses, which plateaued between 150 and 350 mg daily. Tachycardia spontaneously resolved for some but 44% remained tachycardic at day 28. Female sex was associated with early tachycardia at day 14 (p = 0.008) but not at day 28, while age, smoking status, and BMI were not significantly associated with tachycardia.

CONCLUSIONS

Sinus tachycardia occurred in over two thirds of participants during the first month of clozapine titration. Spontaneous resolution of tachycardia in some suggests watchful monitoring may be appropriate prior to treatment with rate-controlling agents such as β-blockers or ivabradine. Long term follow-up is required to determine the effects of sinus tachycardia on cardiovascular outcomes in patients treated with clozapine.

Clinical Characteristics of Inpatients with Schizophrenia Spectrum Disorder Treated with Electroconvulsive Therapy: A Population-Level Cross-Sectional Study: Titre: Caractéristiques cliniques des patients hospitalisés présentant un trouble du spectre de la schizophrénie et traités par électrochocs : Une étude de population transversale

OBJECTIVE

Electroconvulsive therapy (ECT) is an evidence-based treatment for schizophrenia when anti-psychotic medications do not sufficiently control symptoms of psychosis or rapid response is required. Little is known about how it is used in routine clinical practice. The aim of this study was to identify the association of demographic and clinical characteristics with administration of ECT for schizophrenia spectrum disorders (SSD).

METHODS

Among psychiatric inpatients with a diagnosis of SSD in Ontario, Canada (2006-2023), patient-level socio-demographic and clinical characteristics were described in those who did and did not receive ECT. We used multi-variable logistic regression to assess the association between patient-level characteristics and administration of ECT during index hospitalization.

RESULTS

From 164,632 admissions, 2,168 (1.3%) involved exposure to ≥1 inpatient ECT procedure. Compared to those not receiving ECT, those receiving ECT were older, had higher rates of pre-admission medication use, medical and psychiatric comorbidities, outpatient mental health service use, but lower rates of substance use disorders. In the multi-variable logistic regression model, patient-level characteristics most strongly associated with receiving inpatient ECT were the presence of catatonia (odds ratio [OR]: 5.83; 95% confidence interval [95% CI]: 4.01-8.46), comorbid depression (OR: 2.49; 95% CI: 2.07-2.98), obsessive-compulsive disorder (OR: 2.16; 95% CI: 1.55-3.00), while characteristics most strongly associated with not receiving inpatient ECT were myocardial infarction (OR: 0.44; 95% CI: 0.20-0.95) and family conflict towards patient (OR: 0.47; 95% CI: 0.31-0.71). Neither severity of psychotic symptoms, non-command auditory hallucinations nor delusions were associated with administration of ECT.

CONCLUSIONS

While characteristics associated with the use of ECT are generally consistent with the indications for ECT (e.g., catatonia, mood disorders), ECT is rarely used amongst individuals with SSD. Severity of psychotic symptoms was not associated with the use of inpatient ECT suggesting an opportunity to increase the use of ECT in this population.

PLAIN LANGUAGE SUMMARY TITLE

Patient characteristics associated with receiving electroconvulsive therapy in schizophrenia and other psychotic illnesses.

What is the current scope of research assessing patients' and clinicians' perspectives on clozapine treatment? A comprehensive scoping review

OBJECTIVES

Clozapine is continuously underused. The existing systematic reviews addressing barriers to clozapine prescribing primarily focus on clinical staff's attitudes and perceived barriers to prescribing. However, a preliminary literature search revealed additional literature on the subject not previously included in systematic reviews, including literature on patient perspectives. A scoping review is warranted to map the scope of primary studies on patients' and/or clinicians' perspectives on clozapine treatment and to identify gaps in research.

DESIGN

A scoping review was designed and reported in accordance with established guidelines for scoping reviews.

DATA SOURCES

The electronic databases Cochrane Library, CINAHL, Web of Science, PsycINFO, MEDLINE, EMBASE, Google Scholar and two grey literature databases were searched. Furthermore, citation tracking of selected studies was undertaken.

ELIGIBILITY CRITERIA

We included primary, empirical studies reporting clinicians' and/or patients' perspectives on clozapine treatment. No limitation was set for the year of publication or type of primary study.

DATA EXTRACTION AND SYNTHESIS

Two researchers independently screened for studies, extracted the data and coded the content. Findings were summarised visually and narratively.

RESULTS

146 studies were included. Most studies reported on patients' or clinicians' perspectives on active clozapine treatment or on clinicians' perspectives on barriers to clozapine initiation in general. Three gaps in research were identified: (1) clozapine-eligible, yet clozapine-naïve, patients' attitudes towards clozapine commencement, (2) clinicians' reasons for clozapine withholding and perceived facilitators of clozapine treatment in specific patient-cases and (3) patient and clinician perspectives on clozapine discontinuation, continuation and rechallenge in specific patient cases.

CONCLUSIONS

Research on clozapine perspectives tends to repeat itself. Future studies addressing the identified gaps in evidence could provide the insights needed to optimise clozapine utilisation.

Genetic identification of undiagnosed benign ethnic neutropenia in patients receiving clozapine treatment

BACKGROUND

Clozapine therapy presents a risk of agranulocytosis, necessitating monitoring of white blood cell count. The detection of benign ethnic neutropenia (BEN), in which neutropenia can be present without an increased risk of infection, is particularly important in preventing unnecessary withdrawal of clozapine. BEN is strongly linked to the CC homozygote of the single nucleotide polymorphism rs2814778 in the atypical chemokine receptor-1 (ACKR1) gene.

AIMS

We introduced voluntary genetic testing for BEN in one of our clozapine clinics, with the aim of assessing the prevalence of undiagnosed BEN in patients on clozapine.

METHOD

We offered genetic testing for BEN to patients undergoing medium- and long-term clozapine treatment, and conducted a comparative analysis of neutrophil counts across three identified groups: those previously diagnosed with BEN, those with newly discovered BEN and those confirmed by genetic testing not to have BEN.

RESULTS

We conducted genetic testing for BEN on 108 patients. Of these, 16 were already registered as having BEN and had the CC homozygote. A further 26 patients (24% of the cohort) who were previously not diagnosed with BEN by standard haematological monitoring were found to have the CC homozygote on genetic testing. Unadjusted mean neutrophil counts were lowest for those with previously diagnosed BEN (2.5 × 109/L, 95% CI 2.2-2.8; P < 0.001 v. other groups), but those with newly discovered BEN had mean counts that were significantly lower (4.1 × 109/L, 95% CI 3.6-4.7) than those with TT and CT genotypes (5.1 × 109/L, 95% CI 4.7-5.4; P = 0.006).

CONCLUSIONS

Undiagnosed BEN was common in our naturalistic cohort. The integration of genetic testing into standard monitoring would enhance the management of clozapine therapy, potentially allowing for the safe reintroduction or continuation of clozapine in patients with hitherto unrecognised BEN. All current and prospective clozapine patients should be genetically tested for BEN.

High Burden of Ileus and Pneumonia in Clozapine-Treated Individuals With Schizophrenia: A Finnish 25-Year Follow-Up Register Study

OBJECTIVE

The authors used longitudinal biobank data with up to 25 years of follow-up on over 2,600 clozapine users to derive reliable estimates of the real-world burden of clozapine adverse drug events (ADEs).

METHODS

A total of 2,659 participants in the FinnGen biobank project had a schizophrenia diagnosis and clozapine purchases with longitudinal electronic health record follow-up for up to 25 years after clozapine initiation. Diseases and health-related events enriched during clozapine use were identified, adjusting for disease severity. The incidence and recurrence of ADEs over years of clozapine use, their effect on clozapine discontinuation and deaths, and their pharmacogenetics were studied.

RESULTS

Median follow-up time after clozapine initiation was 12.7 years. Across 2,157 diseases and health-related events, 27 were enriched during clozapine use, falling into five disease categories: gastrointestinal hypomotility, seizures, pneumonia, other acute respiratory tract infections, and tachycardia, along with a heterogeneous group including neutropenia and type 2 diabetes, among others. Cumulative incidence estimates for ileus (severe gastrointestinal hypomotility) and pneumonia were 5.3% and 29.5%, respectively, 20 years after clozapine initiation. Both events were significantly associated with increased mortality among clozapine users (ileus: odds ratio=4.5; pneumonia: odds ratio=2.8). Decreased genotype-predicted CYP2C19 and CYP1A2 activities were associated with higher pneumonia risk.

CONCLUSIONS

Clozapine-induced ileus and pneumonia were notably more frequent than has previously been reported and were associated with increased mortality. Two CYP genes influenced pneumonia risk. Pneumonia and ileus call for improved utilization of available preventive measures.

Adjunctive clozapine with bright light mitigates cognitive deficits by synaptic plasticity and neurogenesis in sub-chronic MK-801 treated mice

Schizophrenia impacts about 1 % of the global population, with clozapine (CLZ) being a critical treatment for refractory cases despite its limitations in effectiveness and adverse effects. Therefore, the search for more effective treatments remains urgent. Light treatment (LT) recognized for enhancing cognition and mood, presents a promising complementary approach. This study investigated the effects of CLZ and LT on cognitive impairments in a sub-chronic MK-801 induced schizophrenia mouse model. Results showed that both CLZ and CLZ + LT treatment elevate cognitive performance of sub-chronic MK-801 treated mice in serial behavioral tests over two months. Histological analysis revealed increased dendritic spine density and branching, and synaptic repair in the hippocampus with CLZ and CLZ + LT interventions. Furthermore, both treatments increased brain-derived neurotrophic factor (BDNF) expression in the hippocampus, likely contributing to cognitive amelioration in MK-801 treated mice. Additionally, BrdU labeling revealed that CLZ + LT further enhances neurogenesis in the dentate gyrus (DG) and lateral ventricle (LV) of sub-chronic MK-801 treated mice. These findings may have implications for the development of noninvasive and adjunctive treatment strategies aimed at alleviating cognitive impairments and improving functional outcomes in individuals with schizophrenia.

Developing a validated methodology for identifying clozapine treatment periods in electronic health records

BACKGROUND

Clozapine is the only recommended antipsychotic medication for individuals diagnosed with treatment-resistant schizophrenia. Unfortunately, its wider use is hindered by several possible adverse effects, some of which are rare but potentially life threatening. As such, there is a growing interest in studying clozapine use and safety in routinely collected healthcare data. However, previous attempts to characterise clozapine treatment have had low accuracy.

AIM

To develop a methodology for identifying clozapine treatment dates by combining several data sources and implement this on a large clinical database.

METHODS

Non-identifiable electronic health records from a large mental health provider in London and a linked database from a national clozapine blood monitoring service were used to obtain information regarding patients' clozapine treatment status, blood tests and pharmacy dispensing records. A rule-based algorithm was developed to determine the dates of starting and stopping treatment based on these data, and more than 10% of the outcomes were validated by manual review of de-identified case note text.

RESULTS

A total of 3,212 possible clozapine treatment periods were identified, of which 425 (13.2%) were excluded due to insufficient data to verify clozapine administration. Of the 2,787 treatments remaining, 1,902 (68.2%) had an identified start-date. On evaluation, the algorithm identified treatments with 96.4% accuracy; start dates were 96.2% accurate within 15 days, and end dates were 85.1% accurate within 30 days.

CONCLUSIONS

The algorithm produced a reliable database of clozapine treatment periods. Beyond underpinning future observational clozapine studies, we envisage it will facilitate similar implementations on additional large clinical databases worldwide.

Effective and safe use of intramuscular clozapine in a patient presenting with catatonia and thrombocytopenia

Clozapine is the most effective medication for the management of treatment-resistant schizophrenia and schizoaffective disorder, and its discontinuation can pose significant challenges in treatment. We present a patient with a diagnosis of schizoaffective disorder who was stable on clozapine for a decade until discontinuation due to thrombocytopenia. She experienced a relapse of her illness, presenting with psychotic and catatonic features with poor oral intake and physical health complications requiring a lengthy admission to the hospital. There was a poor response to alternative antipsychotics and a full course of electroconvulsive therapy. Intramuscular (IM) clozapine was initiated due to catatonia and refusal to accept oral medications. After receiving 10 doses of IM clozapine, she started accepting oral clozapine and made a full recovery within a few weeks. The low platelet count was persistent, and a bone marrow biopsy showed results consistent with immune thrombocytopenia being the cause of that low platelet count.

Polymorphisms in ERBB4 and TACR1 associated with dry mouth in clozapine-treated patients

BACKGROUND

Sialorrhea is a common and uncomfortable adverse effect of clozapine, and its severity varies between patients. The aim of the study was to select broadly genes related to the regulation of salivation and study associations between sialorrhea and dry mouth and polymorphisms in the selected genes.

METHODS

The study population consists of 237 clozapine-treated patients, of which 172 were genotyped. Associations between sialorrhea and dry mouth with age, sex, BMI, smoking, clozapine dose, clozapine and norclozapine serum levels, and other comedication were studied. Genetic associations were analyzed with linear and logistic regression models explaining sialorrhea and dry mouth with each SNP added separately to the model as coefficients.

RESULTS

Clozapine dose, clozapine or norclozapine concentration and their ratio were not associated with sialorrhea or dryness of mouth. Valproate use (p = 0.013) and use of other antipsychotics (p = 0.015) combined with clozapine were associated with excessive salivation. No associations were found between studied polymorphisms and sialorrhea. In analyses explaining dry mouth with logistic regression with age and sex as coefficients, two proxy-SNPs were associated with dry mouth: epidermal growth factor receptor 4 (ERBB4) rs3942465 (adjusted p = 0.025) and tachykinin receptor 1 (TACR1) rs58933792 (adjusted p = 0.029).

CONCLUSION

Use of valproate or antipsychotic polypharmacy may increase the risk of sialorrhea. Genetic variations in ERBB4 and TACR1 might contribute to experienced dryness of mouth among patients treated with clozapine.

Overcoming clozapine's adverse events: a narrative review of systematic reviews and meta-analyses

INTRODUCTION

Clozapine is the gold standard treatment for treatment-resistant schizophrenia, however adverse events remain a clinical challenge.

AREAS COVERED

This review presents a narrative synthesis of systematic reviews and meta-analyses that have reported the onset, incidence, prevalence, and management of clozapine's adverse events. We conducted a systematic literature search using PubMed, Embase, PsycINFO, OvidMEDLINE, CINAHL, and the Cochrane Database of Systematic Reviews from inception to April 2024.

EXPERT OPINION

Effective management of clozapine's adverse events necessitates multi-faceted, individualized, and shared-decision strategies. Despite a lack of high-quality systematic evidence, expert inter-disciplinary solutions are provided to help address a critical need for clinical guidance. This 35-year update offers an evidence-based framework to assist clinicians, patients, and caregivers navigate the adverse events associated with clozapine therapy.

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.

Comparison of the Effectiveness and Safety of Clozapine Between Once-Daily and Divided Dosing Regimen in Patients With Treatment-Resistant Schizophrenia

BACKGROUND

Clozapine is the most effective antipsychotic with respect to the incidence of discontinuation and is indicated for treatment-resistant schizophrenia. Although the recommendation for clozapine administration is divided dosing, once-daily dosing of clozapine is commonly prescribed in many countries. However, there is currently no clinical data comparing all-cause discontinuation between the 2 methods of administration of clozapine.

OBJECTIVES

To compare the all-cause discontinuation and safety of clozapine administration between once-daily and divided dosing regimens.

METHODS

This was a retrospective cohort study. Participants were patients with treatment-resistant schizophrenia who had received 300 to 600 mg/day of clozapine for at least 3 months. Data were collected from outpatient medical records at Somdet Chaopraya Institute of Psychiatry. Eligible patients were classified into 2 groups: once-daily dosing and divided dosing. The primary outcome was the all-cause discontinuation rate between groups. The duration of the study was 2 years.

RESULTS

One hundred eighteen patients were included and analyzed in this study (once-daily dosing group: n = 58; divided dosing group: n = 60). There was no significant difference in all-cause discontinuation between the 2 groups (odds ratio 1.03; 95% confidence interval: [0.28, 3.79]: P = 1.00), or adverse events between groups.

CONCLUSION AND RELEVANCE

In patients with treatment-resistant schizophrenia, there were no significant differences in effectiveness or safety between once-daily and divided dosing of clozapine. Further prospective studies with larger sample sizes are required to confirm these findings.

Association between initial clozapine titration and pneumonia risk among patients with schizophrenia in a Korean tertiary hospital

Pneumonia is a significant adverse drug reaction (ADR) associated with clozapine, characterized by high mortality and potential linkage with other inflammatory responses. Despite the critical nature, research regarding the development of pneumonia during initial clozapine titration remains limited. This retrospective study included 1408 Korean inpatients with schizophrenia spectrum disorders. Data were collected from January 2000 to January 2023. Pneumonia developed in 3.5 % of patients within 8 weeks of clozapine initiation. Patients who developed pneumonia were taking a greater number and higher dose of antipsychotics at baseline (2.14 vs. 1.58, p < 0.001; 25.64 vs. 19.34, p = 0.012). The average onset occurred 17.24 days after initiation, on an average dose of 151.28 mg/day. Titration was either paused or slowed in most of these patients, with no reported fatalities. The types of pneumonia included aspiration pneumonia, mycoplasma pneumonia, bronchopneumonia, and COVID-19 pneumonia. Myocarditis, drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome, and urinary tract infections were also identified. Logistic regression analysis revealed that a greater number of concomitant antipsychotics (odds ratio [OR] = 1.59, p = 0.027) and concomitant benzodiazepine use (OR = 2.33, p = 0.005) at baseline were associated with an increased risk of pneumonia. Overall, pneumonia development during clozapine titration is linked with other inflammatory ADRs, suggesting a shared immunological mechanism. Close monitoring is recommended, especially for patients taking multiple antipsychotics and benzodiazepines. Further studies involving repeated measures of clozapine concentrations at trough and steady state, along with a more detailed description of pneumonia types, are warranted.

Association between initial pattern of clozapine titration, concentration-to-dose ratio, and incidence of fever in patients with schizophrenia spectrum disorders in a Korean tertiary hospital

Safe and effective administration of clozapine requires careful monitoring for inflammatory reactions during the initial titration. The concentration-to-dose (C/D) ratio must be taken into account, which may vary among ethnicities. In this retrospective study, 1408 Korean schizophrenia inpatients were examined for during the first 8 weeks of clozapine titration. The average doses of clozapine administered during weeks 1, 2, 4, and 8 were 77.37, 137.73, 193.20, and 212.83 mg/day, with significantly lower doses for females than males. The average C/D ratio was significantly higher in females (1.75 ± 1.04 and 1.11 ± 0.67 ng/mL per mg/day). Patients with higher C/D ratios were more likely to experience fever and were prescribed lower doses of clozapine starting from week 4. In total, 22.1 % of patients developed a fever at an average of 15.74 days after initiating clozapine. Patients who developed a fever were younger, used more antipsychotics at baseline, had a higher C/D ratio, and had a higher incidence of an elevated C-reactive protein level. A higher C/D ratio, use of a greater number of antipsychotics at baseline, and concomitant olanzapine use were risk factors for the development of inflammatory reactions. The incidence of pneumonia, agranulocytosis, and myocarditis within 8 weeks were 3.7 %, 0.3 %, and 0.1 %. In summary, the target dose of clozapine titration is lower for Korean schizophrenia patients, with a higher C/D ratio and more frequent fever compared to Western patients; however, myocarditis occurs rarely. Our findings may contribute to the titration methods for clozapine for the East Asian population.

Patient and caregivers perspective about clozapine: A systematic review

BACKGROUND

Clozapine is a gold standard treatment for treatment-resistant schizophrenia. However, the patients' and caregivers' perception and their experience with clozapine has remained much less explored.

AIM

To review the available literature on the patients' and caregivers' attitudes, perceptions, and experiences with clozapine.

METHODOLOGY

27 original research and review articles published in PubMed-indexed journals till March 2023 in the English language, exploring the patient and/or caregiver/family member's experience with using clozapine, were included.

RESULTS

30-80 %of patients and 92-100 % of caregivers were found to have a positive attitude towards clozapine in terms of its impact on psychopathology, cognitive and social functioning of the patient, and caregiving needs. Most patients and caregivers also found that the positive effects of clozapine outweighed the side effects and distress related to repeated blood testing. However, a lack of satisfaction was noted among both patients and caregivers regarding the knowledge provided to them regarding clozapine, especially regarding its common adverse effects. Discontinuation of clozapine was found to be more commonly done by the patients' accord rather than clinicians, and the perceived side effects like hypersalivation and excessive sedation emerge as important factors that lead to discontinuation rather than the need for repeated blood testing.

CONCLUSIONS

Overall, patients and their caregivers share a positive attitude towards clozapine and perceive it to be an effective and beneficial drug, but more effort needs to be directed by the clinical teams to educate the users of clozapine regarding its complete side effect profile and provide continuous guidance about dealing with the emerging side effects throughout treatment.

High rates of myocarditis with clozapine in the Hunter region of Australia

OBJECTIVE

To study the causes of clozapine treatment discontinuation and measure clozapine-induced myocarditis (CIM) rates in an Australian region, to compare the observed rates of CMI with reports from Australia and the world, and discuss factors related to CIM incidence rates in the region.

METHODS

The study is a retrospective clinical audit of 327 patients prescribed clozapine. All patients were monitored by the mandatory CIM monitoring protocol for the first six weeks of treatment. The validity of a diagnosis of CIM was assessed using six criteria. Socio-demographic and clinical factors and clozapine prescription practices were analysed for their association with CIM. The study could not examine co-existing medical illness, co-prescribed psychotropic medication, genetics, and environmental factors.

RESULTS

CIM occurred in 9.8 % of the cohort after a mean treatment duration of 19.5 days. The diagnosis of CIM was considered valid in all cases. Gender, age at the start of treatment, ethnicity, cumulative clozapine dose, dose titration, and clozapine/norclozapine ratio were unrelated to CIM.

CONCLUSION

The CIM rate in the Hunter region was higher than in the rest of Australia and the world and increased after adopting the monitoring protocol. Over-diagnosis, patient's age and gender, ethnicity, cumulative clozapine dose, dosing titration, and clozapine metabolism rate were unrelated to the high occurrence rates. The possible role of comorbid illnesses, co-prescribed psychiatric medications, genetic, and environmental factors in the etiology of CIM requires further study. The reasons underlying the high rates of CIM in the Hunter region need further exploration.

Management of Cholinergic Rebound After Abrupt Withdrawal of Clozapine: A Case Report and Systematic Literature Review

BACKGROUND

Cholinergic discontinuation symptoms, also known as "cholinergic rebound," from abrupt clozapine discontinuation are characterized by a range of somatic and psychiatric symptoms.

OBJECTIVE

The objective of this study was to describe the clinical features and management options for clozapine withdrawal-associated cholinergic rebound syndrome (henceforth referred to as CWCRS) and present an illustrative case report.

METHODS

Based on a literature search of the databases PubMed, OVID Medline, and Embase as well as reviewing reference lists of relevant past reviews, we carried out a systematic review of case reports on the management of CWCRS from 1946 to 2023.

RESULTS

We identified 10 previously published articles on the clinical management of CWCRS, with a total of 18 patients (6 female, 12 male) with an average age of 43 years (standard deviation 14). Half of the patients had a history of tardive dyskinesia. The mean dose of clozapine before discontinuation was 351 mg/day, with duration of clozapine treatment ranging from 3 weeks to 9 years. Clozapine was the most effective treatment, followed by benztropine.

CONCLUSIONS

Given the small number of cases and the nonexperimental nature of the available studies, this review could not provide reliable data to guide management of CWCRS. The findings, however, suggest that clozapine may be more effective than other commonly used treatment options. With the high rates of discontinuation among patients on clozapine, there is a pressing need for further research into the epidemiology, natural history, and management of clozapine withdrawal syndromes.

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 augmentation with long-acting antipsychotic injections: A case series and systematic review

BACKGROUND

Up to 30% of patients with a diagnosis of treatment-resistant psychosis remain symptomatic despite an optimal trial with the gold standard treatment, clozapine. Emerging evidence suggests the clinical utility of long-acting injections (LAI) in such clinical scenarios. In this study, we aimed to describe clozapine augmentation with LAIs in an inner London hospital and explore the literature on the clinical effectiveness of this treatment modality.

METHODS

Patients prescribed clozapine, who were commenced on a LAI between 2007 and 2023 by the United Kingdom's largest mental health trust, were identified from electronic patient records. First, routine clinical data were used to describe the use, effectiveness, and safety of this augmentation strategy. Second, we conducted a literature search up to 1st June 2023 to identify published studies describing clinical outcomes after clozapine augmentation with a LAI. Clinical outcomes were collated and presented in a table, including hospitalisation rates and quantitative clinical assessments using validated scales.

RESULTS

Of the 1248 patients prescribed clozapine in SLaM, three patients (0.2%) received augmentation with the following LAIs: olanzapine embonate, paliperidone palmitate and pipotiazine palmitate. This treatment strategy was clinically effective and generally well tolerated in all three cases. Twelve published studies between 2010 and 2022 were included in the review. Eight distinct LAIs were reported (4 first and 4 second generation antipsychotics), with risperidone and paliperidone most widely studied. All the identified studies were observational including mirror-image studies, case series and case reports. Duration of follow up varied from 3 months to 3 years. There was evidence that the use of LAIs with clozapine can significantly reduce clinical symptoms, hospitalisation rates and bed days. No serious adverse effects were reported.

CONCLUSION

This preliminary evidence suggests clinical utility of LAIs in alleviating residual symptoms and subsequently reducing hospitalisation rates in patients optimised on clozapine treatment. The current study warrants further investigations including a randomised controlled study to establish the clinical efficacy, tolerability, and place in therapy of this treatment modality.

Schizophrenia Patients Discharged on Clozapine Plus Long-Acting Injectable Antipsychotics From a Public Psychiatric Hospital in Taiwan, 2006-2021

BACKGROUND

Some schizophrenia patients treated with clozapine experience an inadequate response and adherence problems. The purpose of this study was to compare time to rehospitalization within 6 months in schizophrenia patients discharged on 3 clozapine regimens. Additionally, the temporal trend of prescription rate in each group was also explored.

METHODS

Schizophrenia patients discharged from the study hospital from January 1, 2006, to December 31, 2021, (n = 3271) were included in the analysis. The type of clozapine prescribed at discharge was divided into 3 groups: clozapine plus long-acting injectable antipsychotics (clozapine + LAIs), clozapine plus other oral antipsychotics (clozapine + OAPs), and clozapine monotherapy. Survival analysis was used to compare time to rehospitalization within 6 months after discharge among the 3 groups. The temporal trend in the prescription rate of each group was analyzed using the Cochran-Armitage Trend test.

RESULTS

Patients discharged on clozapine + LAIs had a significantly longer time to rehospitalization than those on clozapine + OAPs or clozapine monotherapy. The prescription rates of clozapine + LAIs and clozapine + OAPs significantly increased over time, whereas the prescription rates of clozapine monotherapy significantly decreased.

CONCLUSIONS

Compared with the clozapine + OAPs group, the clozapine + LAIs group had a lower risk of rehospitalization and a lower dose of clozapine prescribed. Therefore, if a second antipsychotic is required for patients who are taking clozapine alone, LAIs should be considered earlier.

Unraveling ethnic disparities in antipsychotic prescribing among patients with psychosis: A retrospective cohort study based on electronic clinical records

BACKGROUND

Previous studies have shown mixed evidence on ethnic disparities in antipsychotic prescribing among patients with psychosis in the UK, partly due to small sample sizes. This study aimed to examine the current state of antipsychotic prescription with respect to patient ethnicity among the entire population known to a large UK mental health trust with non-affective psychosis, adjusting for multiple potential risk factors.

METHODS

This retrospective cohort study included all patients (N = 19,291) who were aged 18 years or over at their first diagnoses of non-affective psychosis (identified with the ICD-10 codes of F20-F29) recorded in electronic health records (EHRs) at the South London and Maudsley NHS Trust until March 2021. The most recently recorded antipsychotic treatments and patient attributes were extracted from EHRs, including both structured fields and free-text fields processed using natural language processing applications. Multivariable logistic regression models were used to calculate the odds ratios (OR) for antipsychotic prescription according to patient ethnicity, adjusted for multiple potential contributing factors, including demographic (age and gender), clinical (diagnoses, duration of illness, service use and history of cannabis use), socioeconomic factors (level of deprivation and own-group ethnic density in the area of residence) and temporal changes in clinical guidelines (date of prescription).

RESULTS

The cohort consisted of 43.10 % White, 8.31 % Asian, 40.80 % Black, 2.64 % Mixed, and 5.14 % of patients from Other ethnicity. Among them, 92.62 % had recorded antipsychotic receipt, where 24.05 % for depot antipsychotics and 81.72 % for second-generation antipsychotic (SGA) medications. Most ethnic minority groups were not significantly different from White patients in receiving any antipsychotic. Among those receiving antipsychotic prescribing, Black patients were more likely to be prescribed depot (adjusted OR 1.29, 95 % confidence interval (CI) 1.14-1.47), but less likely to receive SGA (adjusted OR 0.85, 95 % CI 0.74-0.97), olanzapine (OR 0.82, 95 % CI 0.73-0.92) and clozapine (adjusted OR 0.71, 95 % CI 0.6-0.85) than White patients. All the ethnic minority groups were less likely to be prescribed olanzapine than the White group.

CONCLUSIONS

Black patients with psychosis had a distinct pattern in antipsychotic prescription, with less use of SGA, including olanzapine and clozapine, but more use of depot antipsychotics, even when adjusting for the effects of multiple demographic, clinical and socioeconomic factors. Further research is required to understand the sources of these ethnic disparities and eliminate care inequalities.

Clinician Reasons for Stopping Clozapine: A Retrospective Cohort Study

BACKGROUND

Little information is available on clozapine discontinuation rates in developing country settings.

AIM

The present study aimed to evaluate the incidence and reasons clinicians stopped clozapinine in patients after initiating treatment with the same. In addition, the study also aimed to assess the rechallenge rate, that is, restarting clozapine after a decision to discontinue the same by the clinicians.

METHODOLOGY

The treatment records of 859 patients started on clozapine were reviewed to identify the patients for whom the clinician stopped clozapine at least once because of any reason. The reasons for stopping clozapine were reviewed. In addition, the treatment records were also examined for rechallenge with clozapine at a later date.

RESULTS

Clozapine was stopped by the clinicians in 44 of the 859 patients (5.12%). The most common reason for stopping clozapine was blood dyscrasias (n = 12), followed by poor adherence making the hematological monitoring difficult (n = 9), and intolerable sedation (n = 7). In half of the patients (n = 22), clozapine was restarted by the clinicians for further management of schizophrenia. Successful rechallenge was done in 58.33% of patients with blood dyscrasias, 44.44% with poor adherence, and 71.4% with intolerable sedation.

CONCLUSIONS

The present study suggests clinicians stop clozapine in only 5.14% of cases. The most common reasons for clozapine discontinuation by clinicians include blood dyscrasias, poor medication adherence making it challenging to monitor the hemogram, and sedation. However, in half of the patient's clozapine was rechallenged, and all the attempts of rechallenging were successful.

The lived experience of clozapine discontinuation in patients and carers following suspected clozapine-induced neutropenia

BACKGROUND

Clozapine is the treatment of choice in refractory psychosis. In most countries, clozapine must be stopped indefinitely if white blood cells fall below a defined threshold during routine monitoring. Despite evidence of severe adverse consequences of clozapine discontinuation, published accounts on the lived experiences and perspectives of patients and carers are scarce.

METHOD

We completed semi-structured interviews with patients (n = 4) and family carers (n = 4) on experiences of clozapine cessation following suspected drug-induced neutropenia. Interviews were audio-recorded, transcribed and analysed thematically.

RESULTS

The two overarching themes comprised:(i) stress of clozapine below threshold neutrophil results and (ii) patient and carer priorities.

CONCLUSIONS

There is a suggested need for evidence-based pharmacological and psychological approaches to support patients and carers after clozapine cessation. Such approaches will minimise the potentially negative physical and emotional sequela in the aftermath of a below threshold neutrophil result and reduce the likelihood of experiencing additional health and social inequalities after clozapine discontinuation.

Dropout rates and reasons for dropout among patients receiving clozapine

Background and Aim

The present study aimed to assess the treatment dropout rates, reasons for treatment dropout, and clozapine discontinuation rate among patients attending a tertiary care center in North India.

Materials and Methods

Clozapine data bank was used to identify patients on clozapine, and their treatment records were reviewed for the period Jan 2020-March 2020. Patients who did not follow-up at least once in the last 6 months were considered to have dropped out and were contacted telephonically to understand the reasons for dropout. Treatment records of those following up regularly were reviewed to check if clozapine was discontinued and if so, the reason for the same was evaluated.

Results

Out of 671 patients on clozapine, 495 (73.8%) were still on regular follow-up and the remaining 176 (26.2%) had dropped out of treatment. Out of the 176 patients who had dropped out of treatment, 84 could be contacted. Common reasons for dropout were long distance from the hospital (n = 27), long waiting time for consultation (n = 8), no benefit with treatment (n = 17), side effects with medication (n = 10), moving away to another place (n = 6), refusal by the patient to follow-up (n = 7), patient improved and so did not feel the need to continue treatment (n = 7), and other reasons (n = 37).

Conclusion

About one-fourth of patients who had started treatment with clozapine dropped out from the treatment. The most common reasons for dropout from treatment included long distance from the hospital and no benefit from treatment.

What are patients' experiences of discontinuing clozapine and how does this impact their views on subsequent treatment?

BACKGROUND

Discontinuing what is considered the most effective treatment for treatment-resistant schizophrenia may precipitate feelings of failure or a relapse of illness. Clozapine treatment is discontinued for a variety of reasons, including non-adherence, intolerance, or lack of efficacy. Patients' experiences of discontinuing the "best" treatment and the impact on perceptions of subsequent antipsychotic treatment are important in developing an understanding of the factors affecting people's treatment choices. This study is the first of its type, seeking to explore people's perspectives on clozapine discontinuation.

METHOD

Semi-structured interviews with sixteen patients who had received clozapine and discontinued treatment-thirteen males and three females, age range: thirty-two to seventy-eight years old-were audio-recorded and transcribed. A modified inductive approach to analysis, based on grounded theory, was taken to identify commonalities and differences in patients' perceptions.

RESULTS

The three main themes identified from participants' experiences were: (1) positive and negative effects of treatment; (2) feelings of agency, being the capacity to make decisions about treatment and act independently; (3) choice of treatment in the future. Participants exhibited agency in making choices about medication, including risking relapse, while attempting self-management of medication effects. Different participants perceived the same side effect as beneficial or intolerable. Variation in subsequent treatment choices was reported, with some participants favouring depot (long-acting) injections. A participant was frightened when not told about clozapine's side effects, which led to the participant not being engaged in future treatment decisions. Others, despite suffering serious adverse effects, retained positive perceptions of clozapine; they experienced despair at finding an effective alternative.

CONCLUSIONS

Experiences with clozapine discontinuation evoked powerful emotions and resulted in clozapine being the benchmark for other treatments. Knowledge, agency, and being in control were important to participants in relation to treatment. Personal perceptions of treatments or beliefs about illness could lead to non-adherence. People value the clinician listening to their experiences to better understand their perspective, enabling concerns about medication to be addressed through true shared decision making.

TRIAL REGISTRATION

NHS Health Research Authority and Health and Care Research Wales, IRAS Project ID 225753, Research Ethics Committee (REC) reference: 18/NW/0413, 25/06/2018.

Rates and Reasons for Clozapine Treatment Interruptions: Impact of the Frequency of Hematologic Monitoring and Cardiac Adverse Events

BACKGROUND

Differing rates and reasons for interruptions of clozapine treatment have been reported globally. This article evaluated the rates and reasons for clozapine therapy interruptions in Australia and explored the impact of the frequency of hematological monitoring on these parameters.

METHODS

Data of the patients who were newly commenced on clozapine at three metropolitan public mental health services in Western Australia over 11 years were retrospectively collated. The rate and reasons for clozapine therapy interruptions and their association with the frequency of hematological monitoring, age, sex, and treatment site were analyzed using parametric, nonparametric, and correlational analyses.

RESULTS

Of the 457 patients whose data were collected, 69.6% had an interruption of treatment with 41.2% of those occurring during the period of mandatory weekly hematological monitoring in the first 18 weeks. Nonadherence (57.4%) and adverse effects (28.8%) were the 2 main reasons for the treatment interruptions. Cardiac issues accounted for the majority of the interruptions (61.8%) due to specified adverse effects, and these occurred significantly more commonly within the first 18 weeks. Location, age, and sex did not predict the possibility of treatment interruptions.

CONCLUSIONS

The high rates of clozapine treatment interruption observed during the period of weekly monitoring point toward the need to address the burden of frequent hematological monitoring for patients. Disproportionately higher rates of interruption due to cardiac adverse effects observed in this study compared with research from non-Australian settings raise the possibility of geographical differences in the adverse effects leading to treatment discontinuation.

Second to none: rationale, timing, and clinical management of clozapine use in schizophrenia

Despite its enduring relevance as the single most effective and important evidence-based treatment for schizophrenia, underutilization of clozapine remains considerable. To a substantial degree, this is attributable to a reluctance of psychiatrists to offer clozapine due to its relatively large side-effect burden and the complexity of its use. This underscores the necessity for continued education regarding both the vital nature and the intricacies of clozapine treatment. This narrative review summarizes all clinically relevant areas of evidence, which support clozapine's wide-ranging superior efficacy - for treatment-resistant schizophrenia (TRS) and beyond - and make its safe use eminently feasible. Converging evidence indicates that TRS constitutes a distinct albeit heterogeneous subgroup of schizophrenias primarily responsive to clozapine. Most importantly, the predominantly early onset of treatment resistance and the considerable decline in response rates associated with its delayed initiation make clozapine an essential treatment option throughout the course of illness, beginning with the first psychotic episode. To maximize patients' benefits, systematic early recognition efforts based on stringent use of TRS criteria, a timely offer of clozapine, thorough side-effect screening and management as well as consistent use of therapeutic drug monitoring and established augmentation strategies for suboptimal responders are crucial. To minimize permanent all-cause discontinuation, re-challenges after neutropenia or myocarditis should be considered. Owing to clozapine's unique efficacy, comorbid conditions including substance use and most somatic disorders should not dissuade but rather encourage clinicians to consider clozapine. Moreover, treatment decisions need to be informed by the late onset of clozapine's full effects, which for reduced suicidality and mortality rates may not even be readily apparent. Overall, the singular extent of its efficacy combined with the high level of patient satisfaction continues to distinguish clozapine from all other available antipsychotics.

Combination of two long-acting injectable antipsychotics in treatment-resistant schizophrenia: A retrospective 12-month mirror-image study

To evaluate the efficacy and tolerability of the combination of two long-acting injections of antipsychotics (dual-LAIs) in non-adherent and resistant schizophrenia. Efficacy and tolerability were assessed in 13 patients admitted to a French hospital, using a retrospective 12-month mirror-image design. The number and total duration of hospitalizations significantly decreased after introducing dual-LAIs (2.6 vs. 1.3, P = 0.017; 142 days vs. 95 days, P = 0.046). The average duration of each hospitalization did not differ. No significant differences were observed in tolerance outcomes (body mass index, agranulocytosis, lipid profile, sugar levels). Patients with treatment-resistant schizophrenia and poor medication adherence can derive significant clinical benefits from dual-LAIs.

Antipsychotic prescribing practices for outpatients with schizophrenia and reasons for non-clozapine treatment - Data from a Danish quality assessment audit

BACKGROUND

Clozapine is the gold standard for treating treatment-resistant schizophrenia (TRS) although widely underutilised. Both organisational, patient- and clinician related reasons for the underutilisation have been reported, however, the clinical impact of either in real-world settings is not fully elucidated.

AIM

This audit aimed to evaluate the local antipsychotic (AP) prescribing practices for outpatients with schizophrenia and to assess the spectrum and prevalence of journalised reasons for non-clozapine treatment amongst eligible outpatients.

METHODS

Data on demographics, current and former AP treatments, as well as documented reasons for non-clozapine treatment, was extracted through chart audit.

RESULTS

Of the 668 affiliated outpatients with schizophrenia, 43% were treated with AP polytherapy (APP) and 19.6% with clozapine. The most prevalent reason for clozapine discontinuation was related to side effects whereas the most prevalent reason for refusal or omission of clozapine treatment was related to the associated monitoring regimen.

CONCLUSIONS

This audit showed that APP prescribing is a highly prevalent practice in our services when treating outpatients with schizophrenia and that clozapine is underutilised in a 'last resort' manner. The blood-monitoring regimen associated with clozapine treatment was found to be an important factor in the underutilisation. It seemed, however, that the monitoring constituted a barrier for different reasons, requiring different approaches to remedy. Future studies, directly involving both patients and clinicians in the identification and management of the most clinically relevant barriers and their corresponding facilitators, are warranted.

Genomic Stratification of Clozapine Prescription Patterns Using Schizophrenia Polygenic Scores

BACKGROUND

Treatment-resistant schizophrenia affects approximately 30% of individuals with the disorder. Clozapine is the medication of choice in treatment-resistant schizophrenia, but optimizing administration and dose titration is complex. The identification of factors influencing clozapine prescription and response, including genetics, is of interest in a precision psychiatry framework.

METHODS

We used linear regression models accounting for demographic, pharmacological, and clinical covariates to determine whether a polygenic risk score (PRS) for schizophrenia would be associated with the highest dose recorded during clozapine treatment. Analyses were performed across 2 independent multiancestry samples of individuals from a UK patient monitoring system, CLOZUK2 (n = 3133) and CLOZUK3 (n = 909), and a European sample from a Norwegian therapeutic drug monitoring service (n = 417). In a secondary analysis merging both UK cohorts, logistic regression models were used to estimate the relationship between schizophrenia PRSs and clozapine doses classified as low, standard, or high.

RESULTS

After controlling for relevant covariates, the schizophrenia PRS was correlated with the highest clozapine dose on record for each individual across all samples: CLOZUK2 (β = 12.22, SE = 3.78, p = .001), CLOZUK3 (β = 12.73, SE = 5.99, p = .034), and the Norwegian cohort (β = 46.45, SE = 18.83, p = .014). In a secondary analysis, the schizophrenia PRS was associated with taking clozapine doses >600 mg/day (odds ratio = 1.279, p = .006).

CONCLUSIONS

The schizophrenia PRS was associated with the highest clozapine dose prescribed for an individual in records from 3 independent samples, suggesting that the genetic liability for schizophrenia might index factors associated with therapeutic decisions in cohorts of patients with treatment-resistant schizophrenia.

Clozapine use at a specialised psychiatric hospital in Johannesburg

Background

Clozapine is the gold standard medication for treatment-resistant psychosis, with robust evidence supporting its efficacy in multiple symptom domains. However, clozapine's side effect profile contributes to its underutilisation and discontinuation.

Aim

This study aimed to explore the magnitude of clozapine use and describe factors that impact on its effective use among in-patients.

Setting

Tara Hospital, a specialised psychiatric hospital in Johannesburg.

Methods

This was a retrospective, cross-sectional file review of clozapine-treated patients admitted over the 2-year study period. Data variables included: demographics, clinical information, discharge prescription, clozapine-related side effects and details of clozapine discontinuation, where applicable.

Results

A cohort of 33.2% of patients from Tara's biological wards received a trial of clozapine. Participants experienced anti-cholinergic clozapine-related side effects that included weight gain (79.5%), tachycardia (35.2%) and constipation (35.2%). Clozapine was discontinued in 13.7% of participants, and no life-threatening side effects or deaths occurred. Significantly more use of flupenthixol decanoate (64.3% vs. 30.7%; p = 0.0322) and anticholinergics (35.7% vs. 11.4%; p = 0.0474) occurred in the clozapine-discontinued group. Polypharmacy rates were high for psychiatric and non-psychiatric medications.

Conclusion

One-third of patients received clozapine trials, most of whom continued at discharge. Although side effects occurred frequently, life-threatening side effects did not. Clozapine monitoring protocols, side effect rating scales, pre-emptive management of side effects, lifestyle interventions and clinician education may improve outcomes of clozapine use. The use of plasma clozapine levels may be beneficial.

Contribution

This study expands our limited knowledge regarding current clozapine prescribing trends in South Africa.

Haematological point of care testing for clozapine monitoring

BACKGROUND

Clozapine treatment requires regular full blood counts (FBC) because of the risk of agranulocytosis. Traditionally, FBCs use venous blood samples but the need for frequent venepuncture adversely affects adherence. We investigated the utility of a point of care testing (POCT) finger prick method for clozapine patients.

METHOD

Patients being treated with clozapine, who were having a venous blood sample taken for haematological monitoring, also provided a fingerprick capillary blood sample. The PixCell HemoScreen® POCT analyser was used to test both the capillary and venous samples, and the venous sample was also tested using a standard laboratory method.

RESULTS

We completed FBCs on 226 patients. We found strong correlations between the results from the standard laboratory venous method and the POCT capillary and venous assays for WBC (R = 0.96 & R = 0.99), neutrophils (R = 0.96 & R = 0.97) and eosinophils (R = 0.94 & R = 0.94). Compared with the standard laboratory venous blood method, mean biases for capillary blood POCT method were -0.56 × 10⁹/L for WBC, -0.39 × 10⁹/L for neutrophils, and -0.01 × 10⁹/L for eosinophils. Mean biases for venous blood POCT method were -0.004 × 10⁹/L for WBC, -0.28 × 10⁹/L for neutrophils, and 0.01 × 10⁹/L for eosinophils. Of the 226 patients tested, 10 (4.4%) had levels below clozapine monitoring thresholds (WBC <3.5 × 10⁹/L and Neutrophils <1.5 × 10⁹/L) by capillary blood, and 4 (1.8%) by venous blood by POCT. The standard laboratory method showed 3 of these to be sub-threshold. All cases of neutropenia were identified by capillary and venous POCT.

CONCLUSION

The PixCell HemoScreen® POCT analyser provided results that were comparable with those from a standard venous blood laboratory method for WBC, neutrophil and eosinophil counts. The availability of an accurate capillary monitoring method may result in increased clozapine uptake and better clozapine adherence.

Clozapine haematological monitoring for neutropenia: a global perspective

AIMS

Clozapine is licensed for treatment-resistant psychosis and remains underutilised. This may berelated to the stringent haematological monitoring requirements that are mandatory in most countries. We aimed to compare guidelines internationally and develop a novel Stringency Index. We hypothesised that the most stringent countries would have increased healthcare costs and reduced prescription rates.

METHOD

We conducted a literature review and survey of guidelines internationally. Guideline identification involved a literature review and consultation with clinical academics. We focused on the haematological monitoring parameters, frequency and thresholds for discontinuation and rechallenge after suspected clozapine-induced neutropenia. In addition, indicators reflecting monitoring guideline stringency were scored and visualised using a choropleth map. We developed a Stringency Index with an international panel of clozapine experts, through a modified-Delphi-survey. The Stringency Index was compared to health expenditure per-capita and clozapine prescription per 100 000 persons.

RESULTS

One hundred twocountries were included, from Europe (n = 35), Asia (n = 24), Africa (n = 20), South America (n = 11), North America (n = 7) and Oceania and Australia (n = 5). Guidelines differed in frequency of haematological monitoring and discontinuation thresholds. Overall, 5% of included countries had explicit guidelines for clozapine-rechallenge and 40% explicitly prohibited clozapine-rechallenge. Furthermore, 7% of included countries had modified discontinuation thresholds for benign ethnic neutropenia. None of the guidelines specified how long haematological monitoring should continue. The most stringent guidelines were in Europe, and the least stringent were in Africa and South America. There was a positive association (r = 0.43, p < 0.001) between a country's Stringency Index and healthcare expenditure per capita.

CONCLUSIONS

Recommendations on how haematological function should be monitored in patients treated with clozapine vary considerably between countries. It would be useful to standardise guidelines on haematological monitoring worldwide.

Management of sedation due to clozapine

Sedation is one of the most common adverse effects of clozapine. Although tolerance develops to some extent, a significant proportion of patients continue to experience sedation and associated negative consequences on their quality of life. Sedation is also one of the most common reasons for the discontinuation of clozapine and it is therefore important to proactively manage it. This article provides brief guidance for clinicians.

Comparison of Acute Followed by Maintenance ECT vs Clozapine on Psychopathology and Regional Cerebral Blood Flow in Treatment-Resistant Schizophrenia: A Randomized Controlled Trial

BACKGROUND AND HYPOTHESIS

In treatment-resistant schizophrenia (TRS), Clozapine is only approved treatment with undesirable side-effects, warranting better alternatives. Our hypothesis is acute followed by maintenance Electroconvulsive Therapy (M-ECT) will be comparable in efficacy and safety to Clozapine in TRS.

STUDY DESIGN

In this open-label trial, 60 TRS patients were randomized equally to M-ECT (following an acute-course) or Clozapine. Positive and Negative Syndrome Scale (PANSS), Clinical Global Impression Schizophrenia Scale (CGI-SCH), Montreal Cognitive Assessment (MoCA), and Global assessment of functioning (GAF) were measured and compared within and between the groups at baseline, 6 weeks, 12 weeks, and 24 weeks. SPECT-CT brain was done at baseline and 24 weeks to compare the changes in regional cerebral perfusion between the groups and correlate with the changes in the outcome-measures.

STUDY RESULTS

The PANSS-T scores changes from baseline over the observation-points were significant in both M-ECT and clozapine groups (P < .001), with comparatively better reduction with M-ECT (P < .001). Similar trends were observed in PANSS subscales, CGI-SCH and GAF in both groups, with significantly better improvement with M-ECT over the study-period. After 24 weeks, there was significantly better perfusion with M-ECT in bilateral prefrontal and temporal cortices (P < .05). With M-ECT, a positive correlation was found between changes in PANSS-P scores and left-lateral Temporal cortical perfusion (r = .465, P = .017).

CONCLUSIONS

Acute followed by M-ECT was more effective than clozapine over 6 months in reducing the positive and negative symptoms, general psychopathology, illness-severity, and improving the global functionality in TRS [clinicaltrials.gov: NCT03807882].

Combination With Long-Acting Injectable Antipsychotics and Utilization of Nonstandard Formulations as Compliance Enhancing Methods for Clozapine Users: A Systematic Review and A Case Series

BACKGROUND

Combining clozapine with a long-acting injectable antipsychotic (LAI) or using different, nonstandard formulations of the compound may improve treatment outcomes. We aimed to investigate the utility of the clozapine-LAI combination and different formulations of clozapine for compliance problems of clozapine treatment, and to describe a case series on the combined treatment.

PROCEDURES

We conducted a PubMed search with no date restriction. The number and length of hospitalizations, the results of clinical scales, and adverse events were recorded. We also present a case series of 18 patients using the clozapine-LAI combination. Data were collected from the medical charts and electronic records.

RESULTS

We extracted 9 records describing the use of the clozapine-LAI combination. The case reports and mirror-image studies showed a significant reduction in the number of hospitalizations, length of hospital stays, and number of visits to the emergency department on the combined treatment with no serious adverse events. We included 11 articles for clozapine formulations. The case reports and retrospective data suggested that short-acting intramuscular clozapine was often well tolerated and resulted in an increased acceptance of oral clozapine in the acute phase of illness. In our case series, illness severity and the number of hospitalization per year significantly decreased after the combined treatment, besides a significant improvement in the functioning scores. Hyperprolactinemia and extrapyramidal side effects were reported due to concomitant LAIs.

CONCLUSIONS

Despite the encouraging evidence, the present data are preliminary and mostly based on retrospective studies, and oral-dissolving tablets or oral liquid formulations of clozapine have insufficient evidence for clinical practice. Well-designed, controlled, follow-up studies are needed for both clozapine-LAI combination and different formulations of clozapine.

A retrospective case notes review of the effectiveness and tolerability of metoclopramide in the treatment of clozapine-induced hypersalivation (CIH)

OBJECTIVE

The objective of the study is to explore the long-term effectiveness and tolerability of metoclopramide in the treatment of CIH.

METHOD

This study is a retrospective, observational cohort study of patients prescribed metoclopramide for CIH at the South London & Maudsley (SLaM) NHS Foundation Trust.

RESULTS

Of the 96 patients identified, 14 patients were eligible for inclusion in our study. Five patients continued treatment with a mean duration of 27 months (SD = 17.8), and one patient continued until transfer with a duration of 3 months. Eight patients discontinued treatment after a mean duration of 8 months.

CONCLUSION

Metoclopramide may be an effective and tolerated drug in CIH, but more data is required to establish its place in the pharmacotherapy of this condition.

Using a statistical learning approach to identify sociodemographic and clinical predictors of response to clozapine

BACKGROUND

A proportion of people with treatment-resistant schizophrenia fail to show improvement on clozapine treatment. Knowledge of the sociodemographic and clinical factors predicting clozapine response may be useful in developing personalised approaches to treatment.

METHODS

This retrospective cohort study used data from the electronic health records of the South London and Maudsley (SLaM) hospital between 2007 and 2011. Using the Least Absolute Shrinkage and Selection Operator (LASSO) regression statistical learning approach, we examined 35 sociodemographic and clinical factors' predictive ability of response to clozapine at 3 months of treatment. Response was assessed by the level of change in the severity of the symptoms using the Clinical Global Impression (CGI) scale.

RESULTS

We identified 242 service-users with a treatment-resistant psychotic disorder who had their first trial of clozapine and continued the treatment for at least 3 months. The LASSO regression identified three predictors of response to clozapine: higher severity of illness at baseline, female gender and having a comorbid mood disorder. These factors are estimated to explain 18% of the variance in clozapine response. The model's optimism-corrected calibration slope was 1.37, suggesting that the model will underfit when applied to new data.

CONCLUSIONS

These findings suggest that women, people with a comorbid mood disorder and those who are most ill at baseline respond better to clozapine. However, the accuracy of the internally validated and recalibrated model was low. Therefore, future research should indicate whether a prediction model developed by including routinely collected data, in combination with biological information, presents adequate predictive ability to be applied in clinical settings.

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.

Demographic and clinical characteristics of patients who recommence clozapine following therapy interruptions

OBJECTIVE

The proportion of patients who recommence clozapine after cessation, the time taken to resume clozapine post-cessation, and distinguishing demographic and clinical characteristics of this group have been poorly researched. We evaluated these in the current study.

METHOD

We retrospectively extracted selected demographic and clinical variables and clozapine treatment interruption and recommencement data up to December 2018 of a cohort of 458 patients who first commenced clozapine between 2006 and 2016. The study was conducted at three Australian health services.

RESULTS

Of the 310 (69%) patients who had at least one interruption of clozapine treatment, 170 (54.8%) did not resume clozapine, and 140 (45.2%) recommenced it after the first interruption. More than half of those who recommenced did so within a month and 80% by 12 months. Cox regression analysis revealed that age was significantly associated with recommencement, with a 2% decrease in the likelihood of restarting after an interruption for each year later that clozapine was initially commenced (HR = 0.98 95%CI: 0.97, 0.997, p = 0.02). Those who ceased clozapine due to adverse effects were less likely to restart than those who ceased due to noncompliance (HR = 0.63 95%CI: 0.41, 0.97, p = 0.03). More time on clozapine prior to interruption increased the likelihood of restarting it, with each additional month on clozapine increasing this likelihood by 1% (HR = 1.01 95%CI: 1.01, 1.02, p < 0.001).

CONCLUSION

If the distinguishing demographic and clinical characteristics of the group identified in this study are corroborated through further research, this could further validate the need to identify treatment resistance and commence clozapine early in people with schizophrenia and provide appropriate interventions to those more at risk of permanent discontinuation of clozapine.

Treatment strategies for clozapine-induced nocturnal enuresis and urinary incontinence: a systematic review

BACKGROUND

Clozapine is the most effective medication for treatment-refractory schizophrenia but is associated with significant adverse drug reactions, including nocturnal enuresis and urinary incontinence. This side effect can be burdensome and lead to medication nonadherence and psychotic relapse. Evidence to guide treatment of clozapine-induced nocturnal enuresis and urinary incontinence is sparse. We therefore aimed to synthesize the evidence base to guide management for clinicians, patients, and their carers.

METHODS

We systematically searched PubMed, Embase, PsycInfo, CINAHL, and the Cochrane Trial Registry databases from inception to May 2021 for publications on management of clozapine-induced nocturnal enuresis and urinary incontinence using a PROSPERO preregistered search strategy.

RESULTS

We identified 22 case reports and case series describing 74 patients. Interventions included clozapine dose reduction, nonpharmacological treatment, and pharmacological treatments. Among pharmacological treatments, desmopressin, oxybutynin, trihexyphenidyl, tolterodine, imipramine, amitriptyline, ephedrine, pseudoephedrine, aripiprazole, and verapamil were associated with complete resolution of nocturnal enuresis and urinary incontinence. Balancing evidence for effectiveness against risk of adverse effects, we developed a management framework for clozapine-induced nocturnal enuresis and urinary incontinence.

CONCLUSIONS

Following assessment of urological, psychiatric, pharmacological, and common comorbid medical issues, first-line treatments should be nonpharmacological, including bathroom alarms, voiding before bedtime, and nocturnal fluid restriction. If these interventions do not provide adequate relief, aripiprazole should be trialed. Desmopressin may be considered for severe refractory cases, but monitoring for hyponatremia is essential.

Metabolite Profiling of Clozapine in Patients Switching Versus Maintaining Treatment: A Retrospective Pilot Study

PURPOSE/BACKGROUND

Pharmacokinetics may be of relevance for the risk of clozapine discontinuation. We compared metabolite profiles, accounting for smoking habits, in patients switching versus maintaining clozapine treatment at therapeutic concentrations.

METHODS/PROCEDURES

Adult patients with clozapine serum levels above 1070 nmol/L (350 ng/mL) were retrospectively included from a Norwegian therapeutic drug monitoring service during 2018-2020. Inclusion criteria were (1) known smoking habits, (2) blood sample drawn within 10 to 30 hours after last clozapine intake, and (3) detectable levels of N -desmethylclozapine, clozapine -N -oxide, clozapine-5 N -glucuronide, or clozapine- N + - glucuronide. Patients comedicated with cytochrome P450 enzyme inducers, inhibitors, or valproic acid were excluded. The high-resolution mass spectrometry assay enabled detection of 21 clozapine metabolites. Metabolite profiles were compared between patients switching treatment (switchers), measured as clozapine being replaced by another antipsychotic drug in blood samples, versus maintaining clozapine treatment (nonswitchers) during the study period.

FINDINGS/RESULTS

Of the 84 patients fulfilling the study criteria, 7 patients (8.3%) were identified as clozapine switchers. After correcting for smoking habits, the clozapine-5 N -glucuronide/clozapine ratio was 69% lower ( P < 0.001), while the clozapine- N + -glucuronide/clozapine-5 N -glucuronide ratio was 143% higher ( P = 0.026), respectively, in switchers versus nonswitchers. The other metabolite ratios did not significantly differ between switchers and nonswitchers.

IMPLICATIONS/CONCLUSIONS

The present study found a significantly reduced 5 N -glucuronidation phenotype in patients switching from clozapine at therapeutic serum concentrations (>1070 nmol/L) to other antipsychotic drugs. This may indicate that glucuronidation, as a potential detoxification mechanism, is related to clozapine tolerability. However, the causality of this observation needs to be investigated in future studies with larger patient populations.

Clozapine- and non-clozapine-associated neutropenia in patients with schizophrenia: a retrospective cohort study

INTRODUCTION

The antipsychotic drug clozapine remains underutilized partly because of the risk of life-threatening adverse effects, such as neutropenia. Therefore, an extensive hematological monitoring program was set up to detect neutropenia.

METHODS

In this retrospective cohort study, we used registry-based data from the Capital Region of Denmark to investigate incidence rates of neutropenia among patients with a diagnosis of schizophrenia or other psychotic disorders and treated with clozapine for the first time. In a within-subject design, we compared rates of neutropenia in time periods where patients were exposed to clozapine versus time periods, where they were not exposed to clozapine. We also investigated whether the lengths of clozapine-associated neutropenia (CAN) were related to discontinuation of clozapine treatment.

RESULTS

Data from 520 clozapine users were included. The incidence rate of CAN was 3.2 cases per 100 person-years (95% confidence interval [CI]: 2.1-4.8) throughout the entire study. There was no significant difference in incidence rates of neutropenia during clozapine exposure and non-clozapine exposure, with an incidence rate ratio of 0.7 (95% CI: 0.4-1.3). One episode of severe neutropenia was detected. Episodes of CAN with only one sub-threshold neutrophil count were not associated with higher clozapine discontinuation (26%) than CAN episodes of more than one sub-threshold neutrophil count (28%).

CONCLUSION

In the present study, we could not confirm that clozapine treatment was associated with neutropenia.

Patients' Experiences of Clozapine for Treatment-Resistant Schizophrenia: A Systematic Review

Background

Clozapine is the most effective antipsychotic for patients with treatment-resistant schizophrenia (TRS), however, it remains widely under-utilized in clinical practice. To date, relatively little attention has been given to patients' experience of clozapine. By synthesizing the existing literature, we sought to determine the experiences of patients with TRS treated with clozapine.

Methods

A systematic review was conducted on Embase, Medline, PsychInfo, and PubMed databases for studies from 1956 to 2021. English language studies and those based on adult patients prescribed clozapine for TRS were included.

Results

Thirteen studies were included with a total of 1487 patients and a narrative synthesis was performed. Overall, most patients reported positive experiences of clozapine, with generally high levels of satisfaction, alongside symptom improvement and preference over previous medications. Negative experiences of clozapine were less common, but when mentioned, focused on blood tests and common side effects, including hypersalivation and weight gain.

Conclusions

This is the first systematic review exploring patients' subjective experiences of clozapine for TRS. Findings suggest that patients generally have a favorable experience when being treated with clozapine. However, conclusions are limited by the risk of bias, particularly survivorship bias. High-quality longitudinal studies exploring patients' experiences of clozapine are indicated for the future.

Treatment strategies for clozapine-induced hypotension: a systematic review

BACKGROUND

Clozapine is the most effective medication for treatment-refractory schizophrenia but is associated with significant adverse drug effects, including hypotension and dizziness, which have a negative impact on quality of life and treatment compliance. Available evidence for the management of clozapine-induced hypotension is scant.

OBJECTIVES

Due to limited guidance on the safety and efficacy of pharmacological treatments for clozapine-induced hypotension, we set out to systematically review and assess the evidence for the management of clozapine-induced hypotension and provide guidance to clinicians, patients, and carers.

DESIGN

We undertook a systematic review of the safety and efficacy of interventions for clozapine-induced hypotension given the limited available evidence.

DATA SOURCES AND METHODS

PubMed, Embase, PsycINFO, CINAHL, and the Cochrane trial Registry were searched from inception to November 2021 for literature on the treatment strategies for clozapine-induced hypotension and dizziness using a PROSPERO pre-registered search strategy. For orthostatic hypotension, we developed a management framework to assist in the choice of intervention.

RESULTS

We identified nine case studies and four case series describing interventions in 15 patients. Hypotension interventions included temporary clozapine dose reduction, non-pharmacological treatments, and pharmacological treatments. Midodrine, fludrocortisone, moclobemide and Bovril^® combination, and etilefrine were associated with improvement in symptoms or reduction in orthostatic hypotension. Angiotensin II, arginine vasopressin, and noradrenaline successfully restored and maintained mean arterial pressure in critical care situations. A paradoxical reaction of severe hypotension was reported with adrenaline use.

CONCLUSION

Orthostatic hypotension is a common side effect during clozapine titration. Following an assessment of the titration schedule, salt and fluid intake, and review of hypertensive and nonselective α1-adrenergic agents, first-line treatment should be a temporary reduction in clozapine dose or non-pharmacological interventions. If orthostatic hypotension persists, fludrocortisone should be trialled with monitoring of potassium levels and sodium and fluid intake. Midodrine may be considered second-line or where fludrocortisone is contraindicated or poorly tolerated. For patients on clozapine with hypotension in critical care settings, the use of adrenaline to maintain mean arterial pressure should be avoided.

REGISTRATION

PROSPERO (Registration No. CRD42020191530).

Medication Gaps and Antipsychotic Polypharmacy in Previously Hospitalized Schizophrenia Patients: An Electronic Cohort Study in Three Canadian Provinces

BACKGROUND

Real world evidence about antipsychotics focuses on rehospitalization. Modeling the time course of pharmacotherapy would show patients' adherence to medications and physicians' adherence to medication guidelines. We aimed to calculate the cumulative time spent in second generation antipsychotics (SGAs), gaps, antipsychotic polypharmacy, and clozapine in discharged schizophrenia patients.

METHODS

Hospitalization and pharmacy dispensing data from 2008-2018 in Manitoba, Saskatchewan, and British Columbia were linked and an electronic cohort (N = 2,997) was created (mean follow-up: 49 months, SD = 38). Cohort members were required to have a minimum of 6 weeks medicated with aripiprazole, olanzapine, paliperidone, quetiapine, risperidone, or ziprasidone.

RESULTS

The multistate model predicted that schizophrenia patients accumulated 44 months in SGA monotherapy, 4 months in polypharmacy, 11 months in medication gaps and 17 days in clozapine over a 5-year period. The majority of transitions were between SGA and medication gap. Accumulated time in medication gaps was seven times as much as in clozapine. Each 10% delay in SGA initiation post-discharge was associated with a 2, 1, and 6% higher risk for polypharmacy (95% CI: 1.01-1.02), gap (95% CI: 1.01-1.01), and clozapine (95% CI: 1.04-1.08), respectively.

INTERPRETATION

Schizophrenia patients accumulated more time unmedicated and in polypharmacy compared to clozapine. Either treatment guidelines for schizophrenia are not followed, or real-world challenges hamper their implementation.

Clozapine-induced myocarditis: electronic health register analysis of incidence, timing, clinical markers and diagnostic accuracy

BACKGROUND

Clozapine is associated with increased risk of myocarditis. However, many common side-effects of clozapine overlap with the clinical manifestations of myocarditis. As a result, there is uncertainty about which signs, symptoms and investigations are important in distinguishing myocarditis from benign adverse effects of clozapine. Clarity on this issue is important, since missing a diagnosis of myocarditis or discontinuing clozapine unnecessarily may both have devastating consequences.

AIMS

To examine the clinical characteristics of clozapine-induced myocarditis and to identify which signs and symptoms distinguish true myocarditis from other clozapine adverse effects.

METHOD

A retrospective analysis of the record database for 247 621 patients was performed. A natural language processing algorithm identified the instances of patients in which myocarditis was suspected. The anonymised case notes for the patients of each suspected instance were then manually examined, and those whose instances were ambiguous were referred for an independent assessment by up to three cardiologists. Patients with suspected instances were classified as having confirmed myocarditis, myocarditis ruled out or undetermined.

RESULTS

Of 254 instances in 228 patients with suspected myocarditis, 11.4% (n = 29 instances) were confirmed as probable myocarditis. Troponin and C-reactive protein (CRP) had excellent diagnostic value (area under the curve 0.975 and 0.896, respectively), whereas tachycardia was of little diagnostic value. All confirmed instances occurred within 42 days of clozapine initiation.

CONCLUSIONS

Suspicion of myocarditis can lead to unnecessary discontinuation of clozapine. The 'critical period' for myocarditis emergence is the first 6 weeks, and clinical signs including tachycardia are of low specificity. Elevated CRP and troponin are the best markers for the need for further evaluation.

Cluster Analysis of Clozapine Consumer Perspectives and Comparison to Consumers on Other Antipsychotics

Despite its unique efficacy, clozapine remains underutilized in the United States. Perceptions about clozapine and barriers to its use have been examined among prescribers, but insufficiently studied among consumers. We surveyed 211 antipsychotic consumers (86 on clozapine and 125 on other antipsychotics) on their medication-related perspectives in a public hospital system in Atlanta, Georgia, USA. In contrast to their previous regimen, 72% of clozapine consumers reported they were more satisfied with clozapine. When compared with consumers taking other antipsychotics, clozapine consumers reported more side effects but did not differ on other measures of satisfaction or efficacy. We found Caucasians to be overrepresented among clozapine, as compared to other antipsychotic consumers. Side effects most strongly associated with poor safety ratings were sedation, limb jerking, and dizziness when standing. However, clozapine was only rated less safe by consumers who experienced more than one of these side effects. We used an unsupervised clustering approach to identify three major groups of clozapine consumers. Cluster A (19%) had the lowest safety ratings, aversion to blood work, and a high rate of side effects that associate with lower safety ratings. Cluster B (25%) experienced more hospitalizations and reported satisfaction with clozapine that correlated with efficacy ratings, irrespective of safety ratings. Cluster C (56%) experienced fewer hospitalizations, fewer previous drug trials, greater educational attainment, lower rates of smoking, and rated clozapine more highly. This work identifies common side effects that influence the subjective safety of clozapine and suggests that attitudes toward clozapine depend on context-specific factors.