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Background: Clozapine is the most effective antipsychotic for treatment-resistant psychosis. However, clozapine is underutilised in part because of potential agranulocytosis. Accumulating evidence indicates that below-threshold haematological readings in isolation are not diagnostic of life-threatening clozapine-induced agranulocytosis (CIA)., Aims: To examine the prevalence and timing of CIA using different diagnostic criteria and to explore demographic differences of CIA in patients registered on the UK Central Non-Rechallenge Database (CNRD)., Method: We analysed data of all patients registered on the UK Clozaril ® Patient Monitoring Service Central Non-Rechallenge Database (at least one absolute neutrophil count (ANC) < 1.5 × 10 9 /L and/or white blood cell count < 3.0 × 10 9 /L) between May 2000 and February 2021. We calculated prevalence rates of agranulocytosis using threshold-based and pattern-based criteria, stratified by demographic factors (gender, age and ethnicity). Differences in epidemiology based on rechallenge status and clozapine indication were explored. The proportion of patients who recorded agranulocytosis from a normal ANC was explored., Results: Of the 3029 patients registered on the CNRD with 283 726 blood measurements, 593 (19.6%) were determined to have threshold-based agranulocytosis and 348 (11.4%) pattern-based agranulocytosis. In the total sample (75 533), the prevalence of threshold-based agranulocytosis and pattern-based agranulocytosis was 0.8% and 0.5%, respectively. The median time to threshold-based agranulocytosis was 32 weeks (IQR 184) and 15 (IQR 170) weeks for pattern-based agranulocytosis. Among age groups, the prevalence of pattern-based agranulocytosis and threshold-based agranulocytosis was highest in the >48 age group. Prevalence rates were greatest for White (18%) and male individuals (13%), and lowest for Black individuals (0.1%). The proportion of people who were determined to have pattern-based agranulocytosis without passing through neutropenia was 70%., Conclusions: Threshold-based definition of agranulocytosis may over-diagnose CIA. Monitoring schemes should take into consideration neutrophil patterns to correctly identify clinically relevant CIA. In marked contrast to previous studies, CIA occurred least in Black individuals and most in White individuals.

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., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Clozapine remains the gold standard intervention for treatment-resistant schizophrenia; however, it remains underused, especially for some minority groups. A significant impediment is concern about propensity to neutropenia. The aim of this article is to provide an update on current knowledge relating to: the pattern and incidence of severe blood dyscrasias; the effectiveness of current monitoring regimes in reducing harm; the mechanisms of and the distinctions between clozapine-induced neutropenia and agranulocytosis; benign ethnic neutropenia; and changes to the monitoring thresholds in the USA and other international variations. These all have implications for the practical use of clozapine; specifically, how barriers to initiating, maintaining and restarting clozapine can be understood and in many cases overcome, especially for patients from minority groups, potentially with simpler approaches than the use of lithium or G-CSF.

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., (© 2023 The Authors. Acta Psychiatrica Scandinavica published by John Wiley & Sons Ltd.)

Background: To minimise infection during COVID-19, the clozapine haematological monitoring interval was extended from 4-weekly to 12-weekly intervals in South London and Maudsley NHS Foundation Trust., Aims: To investigate the impact of this temporary policy change on clinical and safety outcomes., Method: All patients who received clozapine treatment with extended (12-weekly) monitoring in a large London National Health Service trust were included in a 1-year mirror-image study. A comparison group was selected with standard monitoring. The proportion of participants with mild to severe neutropenia and the proportion of participants attending the emergency department for clozapine-induced severe neutropenia treatment during the follow-up period were compared. Psychiatric hospital admission rates, clozapine dose and concomitant psychotropic medication in the 1 year before and the 1 year after extended monitoring were compared. All-cause clozapine discontinuation at 1-year follow-up was examined., Results: Of 569 participants, 459 received clozapine with extended monitoring and 110 controls continued as normal. The total person-years were 458 in the intervention group and 109 in the control group, with a median follow-up time of 1 year in both groups. During follow-up, two participants (0.4%) recorded mild to moderate neutropenia in the intervention group and one (0.9%) in the control group. There was no difference in the incidence of haematological events between the two groups (IRR = 0.48, 95% CI 0.02-28.15, P = 0.29). All neutropenia cases in the intervention group were mild, co-occurring during COVID-19 infection. The median number of admissions per patient during the pre-mirror period remained unchanged (0, IQR = 0) during the post-mirror period. There was one death in the control group, secondary to COVID-19 infection., Conclusions: There was no evidence that the incidence of severe neutropenia was increased in those receiving extended monitoring.

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., (© 2023. The Author(s).)

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.

Background: Clozapine is uniquely effective in treatment-resistant psychosis. In the UK, patients must discontinue clozapine indefinitely if they are placed on the Central Non-Rechallenge Database (CNRD) after their haematological parameters fall below particular thresholds. Under exceptional circumstances, patients can be rechallenged on clozapine under an off-licence agreement. In the USA in 2015, restrictive practice was discontinued to allow greater flexibility for clozapine maintenance. The absolute neutrophil count leading to treatment interruption was lowered from less than 1·5 × 10 9 /L to less than 1·0 × 10 9 /L and platelet and white cell count monitoring were ceased. We aimed to investigate the implications of a similar policy change on clozapine use in the UK., Methods: This was a modelling study of all patients registered on the UK CNRD. First, we determined the proportion of patients placed on the database in the UK who would have had to discontinue clozapine treatment under the US Food and Drug Administration (FDA) criteria. Second, we compared the haematological characteristics of patients who did or did not meet FDA criteria for discontinuing clozapine, including the time to registration from clozapine initiation and the proportion of cases of severe neutropenia at registration. Third, we investigated the success rates of clozapine re-challenge for patients that had been placed on the CNRD. Successful rechallenge was defined as no recurrence of CNRD registration., Findings: Between May 2, 2002 and March 1, 2021, 3731 patients were placed on the CNRD, with a mean age of 47 years (SD 15), including 1420 (38%) women and 2311 (62%) men, of whom 3089 (83%) were White, 360 (10%) were Black, 190 (5%) were Asian, and 92 (2%) were classified as other. 566 (15%) of 3731 patients met the equivalent criteria for clozapine discontinuation under the FDA guidelines. The median time to CNRD registration from clozapine initiation was 1·6 years (IQR 0·2-4·9). Data for 519 rechallenged patients were examined; 419 (81%) were successful. Clozapine rechallenge success rates were broadly similar between individuals who did not meet the US CNRD registration criteria (36 [78%] of 46) and those who did meet the criteria (383 [81%] of 473)., Interpretation: Implementing the revised FDA monitoring criteria in the UK would substantially reduce clozapine discontinuation for haematological reasons, which would greatly improve the mental health outcomes of these patients without having a major effect on their physical health., Funding: None., Competing Interests: Declaration of interests DT has received speaker honoraria and research funding from Janssen, Recordati, and Sunovion, and has stock in Psychiatric Genetic Testing outside the submitted work. JHM has received research funding from Lundbeck outside the submitted work. All other authors declare no competing interests. EO is part funded by the Maudsley Charity. JHM, FG, and PM are part funded by the National Institute for Health Research (NIHR) Maudsley Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King's College London. FG is part supported by the Maudsley Charity and the NIHR Applied Research Collaboration South London at King's College Hospital NHS Foundation Trust., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: The evidence for safe and effective interventions to treat the negative and cognitive symptoms of schizophrenia is lacking., Objectives: Vortioxetine is a novel antidepressant that has been used as adjunctive therapy for the treatment of psychosis; however, its effectiveness in clinical practice is relatively unknown. In this study, we aimed to determine the potential clinical effectiveness and safety and tolerability of vortioxetine in psychosis., Design: This is a non-interventional, retrospective study on the add-on use of vortioxetine in a group of people with schizophrenia-spectrum disorders in a large UK NHS mental health trust., Methods: Clinical effectiveness of vortioxetine was retrospectively assessed through the Clinical Global Impression - Severity (CGI-S) scale at 3 months. Safety and tolerability were evaluated through treatment discontinuation rates at 3, 6, and 12 months, and clinical reasons were evaluated at the primary endpoint of 3 months., Results: Data were available for 40 subjects with a diagnosis of schizophrenia or schizoaffective disorder-prescribed vortioxetine treatment; 30 (75%) remained on treatment at 3 months. At CGI-S assessment, 15 of the 35 evaluated subjects reported at least a 1-point improvement, from 5 at baseline to 4 after 3 months of treatment. Twenty-six (65%) remained on treatment at 1-year follow-up. The main reasons for those discontinuing treatment were inadequate response (10%) and manic switch (7.5%), while one subject refused treatment. Tolerability to treatment was good, and 36 subjects (90%) reported no adverse events specific to vortioxetine treatment., Conclusion: Schizophrenia is a complex illness, and there is insufficient treatment response in many individuals. A significant proportion of whom may require adjunctive treatments depending on the nature of the residual symptoms. Vortioxetine could be a potentially safe and effective option in such people, but further controlled studies are required., Competing Interests: Conflict of interest statement: The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s), 2022.)

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., (© 2022. The Author(s).)

Introduction: Antipsychotic pharmacotherapy is considered a first-line treatment in schizophrenia-related disorders and is associated with favorable prognosis and lower mortality rates. However, low adherence rates present a major clinical challenge. In this paper, we will review contemporary approaches to improve adherence to antipsychotic treatment, considering their mechanism of action, safety, tolerability and acceptability., Areas Covered: Novel pharmacological delivery methods included different routes of administration of registered medications (such as intramuscular clozapine preparation and transdermal asenapine), modifications of existing compounds (such as 3-monthly injectable formulation of paliperidone palmitate), and increased interest in oral long-acting medication formulations (such as with penfluridol). In addition, we reviewed innovative technology to monitor adherence, based on the use of electronic digital medicine systems and ingestible sensors., Expert Opinion: All of these diverse approaches were clinically relevant in enhancing treatment adherence and found to be safe and tolerable. The place of each approach is predicated on a personalized approach in each patient, and future research could usefully use large comparative studies to establish robust treatment guidelines. The implementation of new and varied approaches to antipsychotic treatment adherence is welcomed and have the potential to make a significant impact on morbidity in this often difficult-to-treat population.

The wider use of clozapine is limited by the risk of agranulocytosis and the associated requirement for monitoring of neutrophil counts. We searched local electronic patient records for cases of agranulocytosis occurring during clozapine treatment during the period 2007-2020. We found 23 episodes recorded as agranulocytosis in clozapine patients. Of these, nine met pre-defined criteria and were considered episodes of life-threatening agranulocytosis (LTA). These episodes of clozapine-induced LTA exhibited a distinct pattern of continuous and rapid neutrophil count decline to zero or near zero. Mean time for neutrophils to fall from ANC > 2 to ANC <0.5 × 10 9 /L was 8.4 days (range 2-15 days). Each event was also characterised by a prolonged nadir and delayed recovery (range 4-16 days). Non-LTA episodes were, in contrast, brief and benign. We conclude that an important proportion of cases of agranulocytosis identified in people prescribed clozapine are not life-threatening and may not even be clozapine-related. Monitoring schemes should aim to identify true clozapine-induced LTA as opposed to threshold-defined nominal agranulocytosis. Genetics studies might benefit from examining associations with clozapine-induced LTA rather than with recorded cases of agranulocytosis or neutropenia., (© 2022. The Author(s).)

Aim: In this study, we sought to determine clinical outcomes at 1 year for patients prescribed penfluridol in an inner London National Health Service Trust. Using noninterventional data, we describe the use, effectiveness and safety of this treatment modality., Results: We retrospectively followed up 17 patients prescribed penfluridol as part of routine clinical practice. All patients took penfluridol once weekly. Of these patients, 12 (70.6%) were considered treatment resistant. The average duration of illness for this cohort was 10 years (SD = 6.7). At 1 year, nine (53%) patients remained on treatment. Median survival time was not reached at 1-year follow-up; mean time on penfluridol was 251 days (95% confidence interval (CI), 184-318). The mean number of admissions to hospital in the year following penfluridol initiation was 0.6 compared with 0.8, 1 year before initiation ( p  = 0.465). The median number of bed days 1 year before penfluridol initiation was 24, whereas in the year following penfluridol initiation, it was 0 ( p  = 0.514)., Clinical Implications: Although penfluridol is unlicensed in the United Kingdom, limited data suggest that this long-acting oral therapy has the potential to be used safely and effectively for the treatment of psychotic disorders. However, more data are required to establish the place of penfluridol and other potential long-acting oral antipsychotic formulations in the treatment of psychotic disorders.

Importance: People with psychotic disorders have an increased risk of vitamin D deficiency, which is evident during first-episode psychosis (FEP) and associated with unfavorable mental and physical health outcomes., Objective: To examine whether vitamin D supplementation contributes to improved clinical outcomes in FEP., Design, Setting, and Participants: This multisite, double-blind, placebo-controlled, parallel-group randomized clinical trial from the UK examined adults 18 to 65 years of age within 3 years of a first presentation with a functional psychotic disorder who had no contraindication to vitamin D supplementation. A total of 2136 patients were assessed for eligibility, 835 were approached, 686 declined participation or were excluded, 149 were randomized, and 104 were followed up at 6 months. The study recruited participants from January 19, 2016, to June 14, 2019, with the final follow-up (after the last dose) completed on December 20, 2019., Interventions: Monthly augmentation with 120 000 IU of cholecalciferol or placebo., Main Outcomes and Measures: The primary outcome measure was total Positive and Negative Syndrome Scale (PANSS) score at 6 months. Secondary outcomes included total PANSS score at 3 months; PANSS positive, negative, and general psychopathology subscale scores at 3 and 6 months; Global Assessment of Function scores (for symptoms and disability); Calgary Depression Scale score, waist circumference, body mass index, and glycated hemoglobin, total cholesterol, C-reactive protein, and vitamin D concentrations at 6 months; and a planned sensitivity analysis in those with insufficient vitamin D levels at baseline., Results: A total of 149 participants (mean [SD] age, 28.1 (8.5) years; 89 [59.7%] male; 65 [43.6%] Black or of other minoritized racial and ethnic group; 84 [56.4%] White [British, Irish, or of other White ethnicity]) were randomized. No differences were observed in the intention-to-treat analysis in the primary outcome, total PANSS score at 6 months (mean difference, 3.57; 95% CI, -1.11 to 8.25; P = .13), or the secondary outcomes at 3 and 6 months (PANSS positive subscore: mean difference, -0.98; 95% CI, -2.23 to 0.27 at 3 months; mean difference, 0.68; 95% CI, -0.69 to 1.99 at 6 months; PANSS negative subscore: mean difference, 0.68; 95% CI, -1.39 to 2.76 at 3 months; mean difference, 1.56; 95% CI, -0.31 to 3.44 at 6 months; and general psychopathology subscore: mean difference, -2.09; 95% CI, -4.36 to 0.18 at 3 months; mean difference, 1.31; 95% CI, -1.42 to 4.05 at 6 months). There also were no significant differences in the Global Assessment of Function symptom score (mean difference, 0.02; 95% CI, -4.60 to 4.94); Global Assessment of Function disability score (mean difference, -0.01; 95% CI, -5.25 to 5.23), or Calgary Depression Scale score (mean difference, -0.39; 95% CI, -2.05 to 1.26) at 6 months. Vitamin D levels were very low in the study group, especially in Black participants and those who identified as another minoritized racial and ethnic group, 57 of 61 (93.4%) of whom had insufficient vitamin D. The treatment was safe and led to a significant increase in 25-hydroxyvitamin D concentrations., Conclusions and Relevance: In this randomized clinical trial, no association was found between vitamin D supplementation and mental health or metabolic outcomes at 6 months. Because so few patients with FEP were vitamin D replete, the results of this study suggest that this group would benefit from active consideration in future population health strategies., Trial Registration: isrctn.org Identifier: ISRCTN12424842.

Background: Clozapine is the only medication licenced for treating patients with treatment-refractory schizophrenia. However, there are no evidence-based guidelines as to the optimal plasma level of clozapine to aim for, and their association with clinical and functional outcome., Objective: We assessed the relationship between clinical and functional outcome measures and blood concentrations of clozapine among patients with treatment-refractory psychosis., Methods: Data were reviewed in 82 patients with treatment-refractory psychosis admitted to a specialised tertiary-level service and treated with clozapine. Analysis focussed on the relationship between clozapine and norclozapine plasma concentrations and the patient's clinical symptoms and functional status., Results: Clinical symptom improvement was positively correlated with norclozapine plasma concentrations and inversely correlated with clozapine to norclozapine plasma concentrations ratio. Clozapine concentrations showed a bimodal association with clinical improvement (peaks around 350 and 660 ng/ml). Clinical symptom improvement correlated with functional outcomes, although there was no significant correlation between the latter and clozapine or norclozapine plasma concentrations., Conclusion: Clozapine treatment was associated with optimal clinical improvement at two different peak plasma concentrations around 350 and 650 ng/ml. Clinical improvement was associated with functional outcome; however, functionality was not directly associated with clozapine concentrations. A subset of patients may require higher clozapine plasma concentrations to achieve clinical improvement., Competing Interests: Conflict of interest statement: The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s), 2021.)

Background: Benign ethnic neutropenia (BEN) is the most common cause of chronic neutropenia seen in individuals of African, Middle Eastern and West Indian descent. This phenotype is broadly defined by an absolute neutrophil counts (ANC) below 1.8 × 10 9 cells/L in the absence of other causes, without an increased risk of infection. BEN has been implicated as a potential source of disparity in patients treated with clozapine, the antipsychotic of choice in treatment-resistant schizophrenia. Our main objective was to examine the current level of BEN recognition in a cohort of patients treated with clozapine and the potential impact of unidentified BEN on the initiation and maintenance of clozapine treatment., Methods: This was an observational, retrospective analysis of patients registered with clozapine haematological monitoring systems in two large mental health trusts, chosen because they serve an ethnically diverse population. The first objective was to establish certified BEN prevalence in current users of clozapine. The second objective was to explore the stage of treatment at which BEN was identified. The third objective was to evaluate the extent of unrecognised BEN in patients registered on the Central Non-Rechallenge Database (CNRD), a database for patients whose haematological parameters fall below set thresholds when receiving clozapine treatment, meaning they cannot ordinarily be prescribed clozapine again., Results: The study population comprised of 2020 patients on the clozapine register. 111 patients were monitored under BEN criteria. BEN was mostly identified after a below threshold haematological result or clozapine rechallenge (68%) compared to at clozapine initiation (32%). Eight of the 18 (42%) black patients registered on the CNRD were classified as BEN after assessment by a haematologist. Of these 8 patients, none would have met CNRD criteria again if monitored with BEN criteria at clozapine initiation., Conclusions: Current evidence suggests that BEN remains an uncommonly recognised haematological phenotype. Improved timely identification of BEN will reduce unnecessary interruption or discontinuation of clozapine treatment. Our results suggest consideration should also be given to determining BEN status prior to initiating clozapine. Moreover, adoption of current FDA BEN monitoring criteria in the UK may further reduce clozapine discontinuation due to perceived neutropenia as drug toxicity, particularly in treatment-refractory schizophrenia patients., (© 2021. The Author(s).)

Background and Aims: In the United Kingdom, patients on clozapine whose hematological parameters fall below certain thresholds are placed on the Central Non-Rechallenge Database (CNRD), meaning that they cannot be prescribed clozapine again except under exceptional circumstances. This practice was discontinued in the United States in 2015 by expanding the hematological monitoring guidelines, allowing more patients to receive clozapine. Our objective was to investigate the implications this policy change would have on clozapine utilization in the United Kingdom., Methods: This was an observational, retrospective analysis of patients registered on the CNRD in a large mental health trust. The first objective was to compare the number of patients placed on the CNRD under the United Kingdom and the US Food and Drug Administration (FDA) criteria. The second objective was to explore the hematological and clinical outcomes of CNRD patients. The third objective was to investigate the hematological outcomes of patients rechallenged on clozapine after nonrechallengeable status., Results: One hundred and fifteen patients were placed on CNRD from 2002 to 2019, of whom 7 (6%) met the equivalent criteria for clozapine discontinuation under the FDA guidelines. Clinical outcomes, as measured by the Clinical Global Impression-Severity scale, were worse 3 months after clozapine cessation than on clozapine (t = -7.4862; P < .001). Sixty-two (54%) patients placed on CNRD were rechallenged. Fifty-nine of those (95%) were successfully rechallenged; 3 patients were placed back on CNRD, only one of which would have had to stop clozapine again under FDA criteria., Conclusion: Implementation of the updated FDA's monitoring criteria in the United Kingdom would significantly reduce clozapine discontinuation due to hematological reasons. The evidence suggests an urgent need for revising the UK clozapine monitoring guidelines to improve outcomes in treatment-resistant schizophrenia., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center.All rights reserved. For permissions, please email: journals.permissions@oup.com.)

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., (© 2021 The Authors. Acta Psychiatrica Scandinavica published by John Wiley & Sons Ltd.)

Background: Clozapine is uniquely effective in treatment-resistant psychosis but remains underutilised, partly owing to psychotic symptoms leading to non-adherence to oral medication. An intramuscular formulation is available in the UK but outcomes remain unexplored., Aims: This was a retrospective clinical effectiveness study of intramuscular clozapine prescription for treatment initiation and maintenance in treatment-resistant psychosis over a 3-year period., Method: Successful initiation of oral clozapine after intramuscular prescription was the primary outcome. Secondary outcomes included all-cause clozapine discontinuation 2 years following initiation, and 1 year after discharge. Discontinuation rates were compared with a cohort prescribed only oral clozapine. Propensity scores were used to address confounding by indication., Results: Among 39 patients prescribed intramuscular clozapine, 19 received at least one injection, whereas 20 accepted oral clozapine when given an enforced choice between the two. Thirty-six (92%) patients successfully initiated oral clozapine after intramuscular prescription; three never transitioned to oral. Eight discontinued oral clozapine during the 2-year follow-up, compared with 83 out of 162 in the comparator group (discontinuation rates of 24% and 50%, respectively). Discontinuation rates at 1-year post-discharge were 21%, compared with 44% in the comparison group. Intramuscular clozapine prescription was associated with a non-significantly lower hazard of discontinuation 2 years after initiation (hazard ratio 0.39, 95% CI 0.14-1.06) and 1 year after discharge (hazard ratio 0.37, 95% CI 0.11-1.24). The only reported adverse event specific to the intramuscular formulation was injection site pain and swelling., Conclusions: Intramuscular clozapine prescription allowed transition to oral maintenance in an initially non-adherent cohort. Discontinuation rates were similar to patients only prescribed oral clozapine and comparable to existing literature.

Background: Treatment-resistant schizophrenia is a major disabling illness which often proves challenging to manage in a secondary care setting. The National Psychosis Unit (NPU) is a specialised tertiary in-patient facility that provides evidence-based, personalised, multidisciplinary interventions for complex treatment-resistant psychosis, in order to reduce the risk of readmission and long-term care costs., Aims: This study aimed to assess the long-term effectiveness of treatment at the NPU by considering naturalistic outcome measures., Method: Using a mirror image design, we compared the numbers of psychiatric and general hospital admissions, in-patient days, acuity of placement, number of psychotropic medications and dose of antipsychotic medication prescribed before and following NPU admission. Data were obtained from the Clinical Records Interactive Search system, an anonymised database sourced from the South London and Maudsley NHS Trust electronic records, and by means of anonymous linkage to the Hospital Episode Statistics system., Results: Compared with the 2 years before NPU admission, patients had fewer mental health admissions (1.65 ± 1.44 v. 0.87 ± 0.99, z = 5.594, P < 0.0001) and less mental health bed usage (335.31 ± 272.67 v. 199.42 ± 261.96, z = 5.195 P < 0.0001) after NPU admission. Total in-patient days in physical health hospitals and total number of in-patient days were also significantly reduced (16.51 ± 85.77 v. 2.83 ± 17.38, z = 2.046, P = 0.0408; 351.82 ± 269.09 v. 202.25 ± 261.05, z = 5.621, P < 0.0001). The reduction in level of support required after treatment at the NPU was statistically significant (z = -8.099, P < 0.0001)., Conclusions: This study demonstrates the long-term effectiveness of a tertiary service specialising in treatment-resistant psychosis.

Background and Objective: Clozapine is the drug of choice for treatment-resistant schizophrenia. The primary objective of this study was to compare plasma clozapine and N-desmethylclozapine levels in patients switched between 2 liquid formulations [Denzapine suspension and clozapine oral solution (St George's ZTAS)]. Secondary objectives included comparison of safety, tolerability, and patient acceptability., Methods: This was a noninterventional, observational, prospective follow-up of patients consecutively switched between formulations of clozapine liquid in a large inner-city NHS mental health trust. The authors also performed retrospective analysis of outcomes from patient case notes., Results: The authors identified 43 patients receiving Denzapine suspension in the trust. Data were available for 43 patients switched from Denzapine to clozapine oral solution (St George's ZTAS), among whom, 15 (32%) were excluded from the analysis. Of the 28 patients for whom data were available, the 90% confidence interval for the ratio of mean values for corrected Cmin 91.5 (85.2%-98.4%) and uncorrected Cmin 91.2 (84.4%-98.6%) were within the guideline range of bioequivalence (80%-125%). Safety and tolerability profiles were comparable between the 2 formulations (P = 0.10). Patient acceptability was also similar between the brands in most domains. However, there was a taste preference for Denzapine suspension., Conclusions: No significant difference in clozapine plasma levels was observed after switching from Denzapine suspension to a recently introduced clozapine solution. This study also highlights the significance of medicinal characteristics such as taste for patient acceptability and compliance.

Clozapine is the only available treatment for refractory schizophrenia but its use involves frequent physical contact with healthcare workers for the purpose of mandatory blood monitoring. During the COVID-19 pandemic, patients taking clozapine will be self-isolating to reduce the risk of infection, not least because these patients are at high risk of serious illness and fatality because of high rates of diabetes, obesity and pulmonary disease and an increased risk of pneumonia. Problems may also arise because both clozapine-induced myocarditis and neutropenic sepsis share signs and symptoms with COVID-19 (fever, chest pain, dyspnoea, etc.). We recommend decreasing the frequency of physical contacts by extending the blood monitoring interval to 12 weeks in those patients taking clozapine for more than 1 year. To distinguish COVID-19 from clozapine-related physical adverse effects, we suggest an urgent antigen test alongside a full blood count. In those taking clozapine who develop COVID-19, we suggest continuing with clozapine whenever possible (even during ventilation), reducing the dose if necessary in line with blood assay results. Blood monitoring should continue but clozapine should only cease if there is a significant fall in neutrophils (COVID-19 is linked to lymphopenia but not neutropenia). To protect against the likelihood and severity of respiratory infection, we recommend the use of vitamin D in all clozapine patients. Initiation of clozapine is likely to remain problematic while the risk of infection remains, given the degree of physical contact required to assure safety., Competing Interests: Conflict of interest statement: The authors declare that there is no conflict of interest., (© The Author(s), 2020.)

Background: Acute pancreatitis is a rare but recognised complication of clozapine leading to termination of treatment., Case Presentation: We present the case of a 39-year-old man with treatment-resistant schizoaffective disorder and a history of recurrent acute pancreatitis attributed to clozapine. After 15 years of unremitting symptoms with disruptive and aggressive behaviour, he was admitted for a clozapine rechallenge. Despite experiencing two further episodes of acute pancreatitis during clozapine treatment that led to its temporary withdrawal, clozapine was successfully re-established under gastroenterology consultation with close monitoring which resulted in progressively marked improvement of his mental state., Conclusions: This case demonstrates that patients who develop pancreatitis during clozapine treatment may be cautiously rechallenged with specialist gastroenterology support.

Background: Clozapine formulation has been shown to affect plasma concentrations of clozapine and norclozapine. Changes in formulation might result in toxicity or treatment failure., Methods: We identified, from electronic records, patients who switched from clozapine tablets to oral liquid or vice versa and compared plasma concentrations before and after the switch., Results: We identified 13 patients with 85 blood samples who changed formulation of clozapine. Overall mean standardized clozapine plasma level was 0.67 mg/l daily dose on liquid and 0.87 mg/l daily dose on tablets ( p  = 0.035)., Conclusion: Use of clozapine liquid results in lower plasma clozapine concentration than the same dose of tablets., Competing Interests: Conflict of interest statement: The authors declare that there is no conflict of interest., (© The Author(s), 2020.)

Background: People experiencing their first episode of psychosis are often deficient in vitamin D. Observational studies have reported an association between low vitamin D concentrations and poorer subsequent health outcomes in psychosis. A vitamin D deficiency in neonates and children has been linked to a later increased risk of schizophrenia and psychotic-like experiences. This trial aims to examine the effect of high-dose vitamin D supplementation on outcomes in early psychosis. We hypothesise that vitamin D supplementation will be associated with better mental health outcomes., Methods/design: The DFEND study is a multicentre double-blind placebo-controlled parallel-group trial of vitamin D supplementation in people with early psychosis. Patients with an ICD-10 diagnosis of functional psychosis will be randomised in a 1:1 ratio to receive either 120,000 IU/month of vitamin D (cholecalciferol) or a matched placebo for 6 months. The primary outcome is the total Positive and Negative Syndrome Scale (PANSS) score at the 6-month follow-up for all patients. Secondary outcomes include assessment of mood (Calgary Depression Scale), general function (Global Assessment of Functioning), cardiovascular risk (body mass index, waist circumference, C-reactive protein, cholesterol and HbA1c) and vitamin D levels at the 6-month follow-up. Additionally, 3- and 6-month total PANSS scores will be analysed for those with inadequate vitamin D levels at the baseline., Discussion: The DFEND study is the first trial to examine whether vitamin D supplementation in early psychosis is associated with better mental health outcomes. The findings of this study may help to resolve the clinical equipoise regarding the benefits and cost-effectiveness of routine vitamin D supplementation in people with psychosis., Trial Registration: ISRCTN, ISRCTN12424842. Registered on 25 February 2015.

This review discusses the rare but potentially life-threatening cardiovascular side-effects of myocarditis and dilated cardiomyopathy associated with the use of Clozapine. The clinical presentation of these conditions is non-specific, making it difficult to both risk-stratify and identify patients who develop these consequences. This review aims to examine the proposed aetiologies, diagnostic approaches and subsequent management strategies of cardiotoxicity associated with clozapine use; offering guidance to psychiatrists and general physicians. Current evidence highlights the importance of accurate diagnosis to prevent premature and unnecessary cessation of clozapine. Guidance on monitoring and reintroduction of the drug is emerging and current practice recommends a combination of regular monitoring of biomarkers and imaging to make a diagnosis of cardiotoxicity although further work is needed to establish evidence-based guidelines., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Clozapine is the only medication approved for those patients with schizophrenia who do not achieve a clinical response to standard antipsychotic treatment, yet it is still underused. Furthermore, in the case of a partial or minimal response to clozapine treatment, there is no clarity on the next pharmacologic intervention., Methods: The National Psychosis Service is a tertiary referral inpatient unit for individuals with refractory psychosis. Data from 2 pooled data sets (for a total of 325 medical records) were analyzed for treatment trajectories between admission and discharge (2001-2016). Effectiveness of pharmacologic treatment was determined using change in symptoms, assessed using the Operational Criteria (OPCRIT) system applied retrospectively to the medical records. Analysis was focused on identifying the optimal medication regimens impacting clinical status during the admission., Results: Less than a quarter of the patients were on clozapine treatment at the time of admission; this rate increased to 63.4% at the time of discharge. Initiating clozapine during admission (n = 136) was associated with a 47.9% reduction of symptoms as reflected by their OPCRIT score. In cases in which clozapine monotherapy did not achieve sufficient improvement in symptoms, the most effective clozapine augmentation strategy was adding amisulpride (n = 22, 60.8% reduction of symptoms), followed by adding a mood stabilizer (n = 36, 53.7% reduction). A less favorable option was addition of quetiapine (n = 15, 26.7% reduction)., Conclusions: Many people with longer-term and complex refractory illness do respond to clozapine treatment with suitable augmentation strategies when necessary. Furthermore, it is possible to advance clozapine prescribing in these complex patients when they are supported by a skilled and dedicated multidisciplinary team. The optimal therapeutic approach relies on confirmation of diagnosis and compliance and optimization of clozapine dose using therapeutic drug monitoring, followed by augmentation of clozapine with amisulpride or mood stabilizers. There is some preliminary evidence suggesting that augmentation strategies may impact differentially depending on the symptom profile., (© Copyright 2019 Physicians Postgraduate Press, Inc.)

Regular haematological monitoring during clozapine treatment reduces the risk of complications and death from clozapine-related blood dyscrasias. However, many patients in the course of clozapine treatment develop neutropenia unrelated to drug treatment which leads to treatment discontinuation. The minimum haematological threshold allowed for the continuation of clozapine treatment was recently lowered in the US, but not in the UK. In this case series, we present four cases where lowering the haematological cut-off to that used in the US, allowed treatment continuation. Lowering the current UK threshold for clozapine cessation could avoid unnecessary interruptions in treatment with minimal impact on safety.

Summary: 'Rebound' or 'withdrawal' symptoms are frequently observed after a sudden discontinuation of clozapine. We describe a patient with treatment-resistant schizoaffective disorder who developed agranulocytosis on clozapine but was successfully switched to treatment with olanzapine with no deterioration in her condition. We put forward three possible theories which may have accounted for the lack of rebound symptoms in this patient: the pharmacological profile of olanzapine, the anticholinergic effects of hyoscine hydrobromide, and the possibility that this patient may not be treatment-resistant and so have a reduced risk of rebound psychosis due to displaying a different pathophysiology., Declaration of Interest: None.

Clozapine is the only evidence-based antipsychotic for treatment-resistant schizophrenia. However, it has considerable side effects, limiting its usability and reducing patients' adherence. One of the most common and distressing side effects is hypersalivation, which can be debilitating, stigmatizing and potentially dangerous through its association with aspiration pneumonia. There is a paucity of evidence guiding possible treatment strategies for hypersalivation. This study aims to examine the efficacy of hyoscine (scopolamine) for clozapine-induced hypersalivation. Fourteen inpatients diagnosed with treatment-resistant schizophrenia, treated with clozapine and suffering from hypersalivation were randomized to receive hyoscine 0.3 mg and placebo daily for 4 weeks each in a randomized, double-blind, placebo-controlled cross-over trial. The primary outcome was improvement in the Toronto Nocturnal Hypersalivation Scale. The secondary outcomes were change in the mass of the pillowcase, anxiety, depression and quality of life. Hypersalivation improved significantly with hyoscine over placebo when measured by the Toronto Nocturnal Hypersalivation Scale (odds ratio=0.21, 95% confidence interval: 0.16-0.28, P<0.001). No significant difference was observed in any of the secondary outcomes. This study showed a beneficial effect of hyoscine over placebo for clozapine-induced hypersalivation.

Background: Schizophrenia has a 1% prevalence in the population; 30% of these patients are treatment refractory. Clozapine is the only drug licensed to treat treatment refractory psychosis, but concerns about potential adverse effects result in only a proportion of eligible patients being treated. Although a well-documented neutropenia risk is mitigated by routine blood testing, cardiac toxicity is a commonly cited reason to discontinue clozapine treatment. However, there is little data on the real-life cardiac outcomes in those receiving clozapine treatment., Methods: Retrospective review of electrocardiogram, echocardiogram, and clinical outcomes in 39 inpatients with treatment-refractory schizophrenia, treated with clozapine and other antipsychotic medication, referred for cardiology opinion., Results: Commonest reasons for referral were development of left ventricular (LV) impairment or sinus tachycardia with normal LV function. Patients were reviewed by a range of cardiologists, receiving varied interventions.Median LV ejection fraction in the clozapine group was normal (52%). Serial echocardiograms demonstrated that clozapine-treated patients with LV impairment had no change in LV ejection fraction over a 4-month follow-up. Left ventricular ejection fraction did not differ between patients treated with clozapine and other antipsychotics. However, over an 11-year follow-up period, 48% of patients had discontinued clozapine treatment., Conclusions: This naturalistic study demonstrates that clozapine is not associated with significant cardiac mortality or morbidity. There is a real need for multidisciplinary working between specialist cardiologists and psychiatrists caring for these complex patients to facilitate optimal long-term physical and mental health outcomes.

Purpose/background: Clozapine is associated with hematological abnormalities, with neutropenia and agranulocytosis of most concern. Granulocyte colony-stimulating factor (G-CSF) has been used to support clozapine rechallenge after neutropenia with the aim of maintaining the neutrophil count. This study aims to explore the practice, use, safety, and efficacy of G-CSF in this context., Methods/procedures: We conducted a systematic review to identify all studies investigating or describing G-CSF as a prophylaxis to enable continued clozapine treatment during a rechallenge., Findings/results: We identified 32 reports of patients who received G-CSF either regularly (n = 23) or as required (n = 9) to support clozapine rechallenge after an episode of neutropenia necessitating discontinuation of clozapine. Seventy-five percent (n = 24) of published cases remained on clozapine with the use of continual prophylactic G-CSF or after single G-CSF administrations (n = 8). Seventy percent (n = 16) of patients in receipt of continual prophylactic G-CSF were successfully maintained on clozapine. However, 1 of the 3 episodes of rechallenge in those with a history of severe agranulocytosis (absolute neutrophil count <0.1 × 10/L) had a recurrence of agranulocytosis at week 9., Implications/conclusions: Our findings suggest that G-CSF can sometimes be safely used to support the maintenance of normal neutrophil counts and clozapine use after neutropenia. Publication bias is an important limitation, however. Also, few reports clearly documented the presence or absence of an independent nonclozapine cause of the index neutropenia, which may have increased success rates. Furthermore, adverse events were not systematically recorded. Prospective studies are needed to determine safety because if agranulocytosis occurs on clozapine while supported by G-CSF, there is no obvious alternate rescue therapy to promote granulopoiesis. From the available data, it is not possible to recommend this course of action for someone with a true clozapine agranulocytosis.

Purpose/background: Clozapine is associated with hematological abnormalities, notably neutropenia, which may progress to agranulocytosis. Granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) have been used to reduce the frequency and duration of clozapine-associated neutropenia. This review aims to explore the use, efficacy, and tolerability of these cytokines in the treatment of clozapine-associated agranulocytosis., Methods/procedures: We conducted a systematic review of published interventional and observational studies, case series, and case reports where G-CSF/GM-CSF was used to treat clozapine-associated agranulocytosis., Findings/results: We identified 29 reports (40 patients). The median duration of neutrophil recovery time after stopping clozapine and starting cytokine treatment was 7 days (range, 2-13 days) for those with agranulocytosis (absolute neutrophil count < 0.5 × 10 cells/L). Ninety-four percent (n = 29) had no serious adverse reactions, and no deaths occurred., Implications/conclusions: Our findings indicate that G-CSF/GM-CSF use is well tolerated and suggest that G-CSF can sometimes be safely used to reduce the duration of neutropenia associated with clozapine use. However, the interpretation of this outcome is difficult, given the likely publication bias for positive outcomes in case reports.

Objective: Certain patients with treatment-refractory schizophrenia may be rechallenged with clozapine following previous neutropenia. Evidence guiding patient selection and the effectiveness of lithium and granulocyte-colony stimulating factor (G-CSF) in rechallenge is limited, and factors associated with successful outcomes are unclear., Method: Outcomes were studied in patients rechallenged with clozapine at a tertiary referral center between January 2007 and December 2013, following 1 or more previous trials terminated due to neutropenia, defined as an absolute neutrophil count (ANC) < 1.5 × 10(9)/L. Demographic characteristics, details of each clozapine trial including ANC, and coprescribed medication were extracted, and factors associated with rechallenge outcomes were examined., Results: Nineteen patients underwent clozapine rechallenge following previous neutropenia; 4 (21%) experienced further neutropenia, 2 of which developed agranulocytosis. Compared to successfully rechallenged patients, unsuccessfully rechallenged patients were significantly older (t = 2.10, P = .05), experienced onset of neutropenia sooner (W = 10.0, P = .03), and were more commonly coprescribed valproate. In addition to 5 patients with benign ethnic neutropenia (BEN), 8 patients not of an ethnicity associated with BEN also had idiopathic low neutrophil counts at baseline; lithium and G-CSF coprescription facilitated successful rechallenge in these patients., Conclusions: In this selected population, the initial neutropenia was unlikely to be related to clozapine in a substantial proportion of cases. This group was successfully rechallenged following careful consideration of the risks and benefits, and lithium and G-CSF contributed to allowing continued clozapine therapy. In addition to black patients, other ethnic groups can have persistently low ANC unrelated to clozapine., (© Copyright 2015 Physicians Postgraduate Press, Inc.)

There are a variety of noradrenergic antidepressants available, most of which act by inhibiting neuronal noradrenaline re-uptake, although few drugs are specific for this action. Where drugs have numerous actions the adverse effects of noradrenaline reuptake may be difficult to isolate, although in this respect the adverse effects of reboxetine, a specific noradrenaline re-uptake inhibitor, are illuminating. Noradrenergic antidepressants typically cause minor changes in blood and heart rate, sweating and insomnia. Other pharmacological actions shown by non-specific antidepressants may act to worsen or mitigate these adverse effects. Noradrenergic drugs are less likely than selective serotonin reuptake inhibitors (SSRIs) to cause sexual dysfunction but more likely to cause urinary hesitancy. Doubts remain over the relative propensity for antidepressants with different modes of action to cause diabetes and hyponatraemia. Noradrenergic actions do not seem to confer a risk of death in overdose.

Clozapine is the treatment of choice for treatment-resistant schizophrenia, but it is associated with a risk of neutropaenia and agranulocytosis. Clozapine use is regulated by mandatory blood monitoring in the UK, requiring cessation of treatment should the absolute neutrophil count (ANC) drop below specified values. Benign reductions in the ANC in non-white populations are common, and this can preclude a patient from receiving treatment with clozapine. A diagnosis of benign ethnic neutropaenia can reduce these treatment restrictions (UK specific), but the degree of neutropaenia can be significant enough to still prevent treatment. In this report, we show that response to granulocyte colony stimulating factor (G-CSF) may be quite variable and difficult to predict, but with careful monitoring it can be used to increase the ANC count and allow continued treatment with clozapine.

Clozapine is the treatment of choice in refractory schizophrenia. Its more extensive use is limited by adverse effects and the need for regular blood monitoring. However, black patients are disadvantaged with respect to clozapine usage. Lower baseline Absolute Neutrophil Count compared with Whites leads to a greater frequency of blood testing, treatment interruptions and discontinuation. This may in part be explained by Benign Ethnic Neutropenia, but too few black patients are thus registered. The four cases described in this report underline some of the difficulties if this problem is under-recognized. Moreover, in our sample of 191 clozapine recipients in an inner London hospital, black patients account for approximately half, but only a small proportion, 8/95 (8.4%) are registered as having Benign Ethnic Neutropenia. None of the Benign Ethnic Neutropenia-registered patients discontinued treatment for haematological reasons. To optimize clozapine treatment and improve long-term outcomes, a significantly greater proportion of Black patients should be registered as having Benign Ethnic Neutropenia.