Clozapine-induced agranulocytosis/granulocytopenia: mechanisms and monitoring

Time for a change to clozapine haematological monitoring

OBJECTIVES

This paper critiques the haematological monitoring guidelines for clozapine. It describes the history of clozapine, as well as the pathophysiology and epidemiology of clozapine-induced neutropenia (CIN) and agranulocytosis (CIA). The paper appraises the extant literature on mandatory clozapine haematological monitoring.

CONCLUSION

Contemporary Australian protocols for clozapine haematological monitoring are not consistent with the current evidence base. CIN and CIA are rare occurrences, and the associated risk of death is low. Potential modifications to existing guidelines include changing neutrophil thresholds for patients with benign ethnic neutropenia and reducing the frequency or removing haematological monitoring after two years of clozapine treatment.

Evidence for the Role of the Mitochondrial ABC Transporter MDL1 in the Uptake of Clozapine and Related Molecules into the Yeast Saccharomyces cerevisiae

Clozapine is an antipsychotic drug whose accumulation in white cells can sometimes prove toxic; understanding the transporters and alleles responsible is thus highly desirable. We used a strategy in which a yeast (Saccharomyces cerevisiae) CRISPR-Cas9 knock-out library was exposed to cytotoxic concentrations of clozapine to determine those transporters whose absence made it more resistant; we also recognised the structural similarity of the fluorescent dye safranin O (also known as safranin T) to clozapine, allowing it to be used as a surrogate marker. Strains lacking the mitochondrial ABC transporter MDL1 (encoded by YLR188W) showed substantial resistance to clozapine. MDL1 overexpression also conferred extra sensitivity to clozapine and admitted a massive increase in the cellular and mitochondrial uptake of safranin O, as determined using flow cytometry and microscopically. Yeast lacking mitochondria showed no such unusual accumulation. Mitochondrial MDL1 is thus the main means of accumulation of clozapine in S. cerevisiae. The closest human homologue of S. cerevisiae MDL1 is ABCB10.

Long-term persistence of the risk of agranulocytosis with clozapine compared with other antipsychotics: a nationwide cohort and case-control study in Finland

BACKGROUND

Agranulocytosis is a life-threatening side-effect of clozapine, the only approved drug for treatment-resistant schizophrenia. The long-term profile of this complication has not yet been well established. Here we aim to describe the risk of clozapine-induced agranulocytosis over the long term.

METHODS

We used the entire population of Finland to identify people diagnosed with schizophrenia or schizoaffective disorder between 1972 and 2014 and developed a Kaplan-Meier model of time to diagnosis of agranulocytosis during clozapine versus non-clozapine treatment over a 22-year observation period (1996 to 2017). Next, we developed a nested case-control model for agranulocytosis matching by sex, age, time since diagnosis, and being in the incident cohort on a 1 to 5 ratio. Various durations of use for clozapine and non-clozapine antipsychotic treatment were compared to the modal antipsychotic use duration, deriving adjusted odds ratios (aORs) in a multivariable regression model. Recurrence and lethality rates for clozapine-induced agranulocytosis were described. These data reflect on all individuals with lived experience of schizophrenia in Finland during the study time, although individuals with lived experience were not included in the design of the study.

FINDINGS

We identified 61 769 people with schizophrenia or schizoaffective disorder (14 037 individuals treated with clozapine and 47 732 individuals treated with non-clozapine antipsychotics), with a mean age of 46·67 years (IQR 34·44-57·61), of whom 30 721 (49·7%) were female and 31 048 (50·3%) were male (data on ethnicity not available). Among those, 398 individuals were diagnosed with agranulocytosis (231 individuals treated with clozapine and 167 individuals treated with non-clozapine antipsychotics), representing a cumulative incidence of agranulocytosis for 1·37% (95% CI 0·58-3·16) on clozapine and 0·13% (0·04-0·23) on non-clozapine antipsychotics. In the case (n=398) versus control (n=1987) model, the risk of clozapine-induced agranulocytosis decreased steeply over time from an aOR of 36·01 (95% CI 16·79-77·22) for less than 6 months on clozapine to 4·38 (1·86-10·34) for clozapine use of 54 months or more. Only one of 3559 individuals starting clozapine died because of clozapine-induced agranulocytosis.

INTERPRETATION

The risk of clozapine-induced agranulocytosis decreases steeply over time but might be persistently greater than that of non-clozapine antipsychotics. This long-term risk excess seems small in absolute terms compared with the known magnitude of the advantages of clozapine in relevant outcomes, including life expectancy. Given the widespread underuse of clozapine, relaxing the long-term neutrophil monitoring could favour the advantages of long-term clozapine use, including greater life expectancy, without incurring the intolerable risk of clozapine-induced agranulocytosis.

FUNDING

Northwell Health and Sigrid Jusèlius Foundation.

The Role of Total White Blood Cell Count in Antipsychotic Treatment for Patients with Schizophrenia

BACKGROUND

Total white blood cell count (TWBCc), an index of chronic and low-grade inflammation, is associated with clinical symptoms and metabolic alterations in patients with schizophrenia. The effect of antipsychotics on TWBCc, predictive values of TWBCc for drug response, and role of metabolic alterations require further study.

METHODS

Patients with schizophrenia were randomized to monotherapy with risperidone, olanzapine, quetiapine, aripiprazole, ziprasidone, perphenazine or haloperidol in a 6-week pharmacological trial. We repeatedly measured clinical symptoms, TWBCc, and metabolic measures (body mass index, blood pressure, waist circumference, fasting blood lipids and glucose). We used mixed-effect linear regression models to test whether TWBCc can predict drug response. Mediation analysis to investigate metabolic alteration effects on drug response.

RESULTS

At baseline, TWBCc was higher among patients previously medicated. After treatment with risperidone, olanzapine, quetiapine, perphenazine, and haloperidol, TWBCc decreased significantly (p < 0.05). Lower baseline TWBCc predicted greater reductions in Positive and Negative Syndrome Scale (PANSS) total and negative scores over time (p < 0.05). We found significant mediation of TWBCc for effects of waist circumference, fasting low-density lipoprotein cholesterol, and glucose on reductions in PANSS total scores and PANSS negative subscale scores (p < 0.05).

CONCLUSION

TWBCc is affected by certain antipsychotics among patients with schizophrenia, with decreases observed following short-term, but increases following long-term treatment. TWBCc is predictive of drug response, with lower TWBCc predicting better responses to antipsychotics. It also mediates the effects of certain metabolic measures on improvement of negative symptoms. This indicates that the metabolic state may affect clinical manifestations through inflammation.

Mediation and longitudinal analysis to interpret the association between clozapine pharmacokinetics, pharmacogenomics, and absolute neutrophil count

Clozapine is effective at reducing symptoms of treatment-resistant schizophrenia, but it can also induce several adverse outcomes including neutropenia and agranulocytosis. We used linear mixed-effect models and structural equation modelling to determine whether pharmacokinetic and genetic variables influence absolute neutrophil count in a longitudinal UK-based sample of clozapine users not currently experiencing neutropenia (N = 811). Increased daily clozapine dose was associated with elevated neutrophil count, amounting to a 133 cells/mm3 rise per standard deviation increase in clozapine dose. One-third of the total effect of clozapine dose was mediated by plasma clozapine and norclozapine levels, which themselves demonstrated opposing, independent associations with absolute neutrophil count. Finally, CYP1A2 pharmacogenomic activity score was associated with absolute neutrophil count, supporting lower neutrophil levels in CYP1A2 poor metabolisers during clozapine use. This information may facilitate identifying at-risk patients and then introducing preventative interventions or individualised pharmacovigilance procedures to help mitigate these adverse haematological reactions.

A systematic review of the role of clozapine for severe borderline personality disorder

RATIONALE

Clozapine is a unique medication with a potential role in the treatment of severe borderline personality disorder (BPD).

OBJECTIVES

The review examines the effectiveness of clozapine as a medication for management for severe BPD with high risk of suicide, violence or imprisonment, and aims to help guide clinical practice in managing severe BPD.

METHODS

A database search of the terms "Clozapine" AND "BPD"; "Antipsychotics" AND "BPD"; "Clozapine" AND "Borderline Personality Disorder"; and "Antipsychotics" AND "Borderline Personality Disorder" were performed in CINAHL, Cochrane Library, Embase, Medline, PsychINFO, PubMed, and Web of Science. Full-text articles of clinical clozapine use for BPD were included for review.

RESULTS

A total of 24 articles consisting of 1 randomised control trial, 10 non-controlled trials, and 13 case reports were identified. Most of the studies reported benefits from clozapine when used for severe BPD. Many of the studies focused on clozapine use in BPD patients at high risk of suicide. Results from these non-controlled and case reports support the use of clozapine in patients with severe BPD at high risk of suicide.

CONCLUSION

There may be a role for clozapine in treating severe treatment refractory BPD, especially for those patients at high risk of suicide and frequent hospitalisations.

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.

Valproate-related neutropenia and lithium-related leukocytosis in patients treated with clozapine: a retrospective cohort study

BACKGROUND

Neutropenia is a noteworthy side effect of clozapine, which might warrant this drugs' discontinuance for safety. Studies have revealed that the risk of neutropenia increases with concurrent administration of valproate, but the evidence was limited. Conversely, lithium may have an ameliorating effect on clozapine-induced neutropenia. This study explored the effects of valproate and lithium on white blood cell counts in patients treated with clozapine.

METHODS

We retrospectively investigated the electronic medical records from one tertiary psychiatric hospital in Taiwan and enrolled patients discharged between January 1, 2006, and December 31, 2017, with clozapine prescriptions. We scrutinized their demographic data, medications, and hematological results at discharge and during follow-up outpatient clinic visits over the subsequent 3 years. Patients were classified into four groups: clozapine only (CLO), clozapine and valproate (CLO + VAL), clozapine and lithium (CLO + Li), and clozapine, valproate, and lithium (CLO + VAL + Li). We also identified hematological events (neutropenia or leukocytosis) of these patients during outpatient follow-ups.

RESULTS

Of the included 1084 patients, 55(5.1%) developed neutropenia. Concurrent valproate use (odds ratio [OR] = 3.49) and older age (p = .007) were identified as risk factors. Moreover, 453 (41.79%) patients developed leukocytosis. Younger age; male sex; and concurrent use of lithium (OR = 3.39, p < .001), clozapine daily dosage, and benzodiazepines were the risk factors for leukocytosis.

CONCLUSION

Concurrent valproate use and older age are associated with the development of neutropenia in patients treated with clozapine. Concurrent lithium usage, younger age, male sex, and concurrent benzodiazepine use might be related to leukocytosis.

Antipsychotic drug-induced neutropenia: results from the AMSP drug surveillance program between 1993 and 2016

Neutropenia and agranulocytosis (N&A) are relatively rare, but potentially fatal adverse drug reactions (ADR). This study presents cases of N&A related to one or more antipsychotic drugs (APDs) in psychiatric inpatients. Data on APD utilization and reports of N&A caused by APDs were analyzed by using data from an observational pharmacovigilance program in German-speaking countries-Arzneimittelsicherheit in der Psychiatrie (AMSP)-from 1993 to 2016. 333,175 psychiatric inpatients were treated with APDs for schizophrenia and other indications during the observation period. A total of 124 cases of APD-induced N&A were documented, 48 of which fulfilled the criteria for agranulocytosis, corresponding to a rate of 0.37, respectively, 0.14 in 1000 inpatients treated with APDs. Neutropenia was more often detected in women, whereas there was no difference regarding sex in cases of agranulocytosis. Clozapine had the highest relative risk for inducing N&A and was imputed alone as a probable cause of N&A in 60 cases (1.57‰ of all patients exposed). Perazine showed the second highest relative risk with 8 cases and an incidence 0.52‰, followed by quetiapine (15 cases resp. 0.23‰ of all patients exposed) and olanzapine (7 cases; 0.13‰ of all patients exposed). N&A most often occurred during the first 3 months of treatment. Overall N&A are severe and potentially fatal complications that can occur during treatment with APDs. The results from this study largely agree with the currently available literature, highlighting the positive effects of alertness and established appropriate monitoring.

Bioactivation and Reactivity Research Advances - 2021 year in review

This year's review on bioactivation and reactivity began as a part of the annual review on biotransformation and bioactivation led by Cyrus Khojasteh (Khojasteh et al., 2021, 2020, 2019, 2018, 2017; Baillie et al., 2016). Increased contributions from experts in the field led to the development of a stand alone edition for the first time this year focused specifically on bioactivation and reactivity. Our objective for this review is to highlight and share articles which we deem influential and significant regarding the development of covalent inhibitors, mechanisms of reactive metabolite formation, enzyme inactivation, and drug safety. Based on the selected articles, we created two sections: (1) reactivity and enzyme inactivation, and (2) bioactivation mechanisms and safety (Table 1). Several biotransformation experts have contributed to this effort from academic and industry settings.

Adverse Drug Reactions in Relation to Clozapine Plasma Levels: A Systematic Review

Clozapine is the gold standard for treatment-resistant schizophrenia. Serious and even life-threatening adverse effects, mostly granulocytopenia, myocarditis, and constipation, are of great clinical concern and constitute a barrier to prescribing clozapine, thus depriving many eligible patients of a lifesaving treatment option. Interestingly, clozapine presents variable pharmacokinetics affected by numerous parameters, leading to significant inter- and intra-individual variation. Therefore, therapeutic drug monitoring of plasma clozapine levels confers a significant benefit in everyday clinical practice by increasing the confidence of the prescribing doctor to the drug and the adherence of the patient to the treatment, mainly by ensuring effective treatment and limited dose-related side effects. In the present systematic review, we aimed at identifying how a full range of adverse effects relates to plasma clozapine levels, using the Jadad grading system for assessing the quality of the available clinical evidence. Our findings indicate that EEG slowing, obsessive-compulsive symptoms, heart rate variability, hyperinsulinemia, metabolic syndrome, and constipation correlate to plasma clozapine levels, whereas QTc, myocarditis, sudden death, leucopenia, neutropenia, sialorrhea, are rather unrelated. Rapid dose escalation at the initiation of treatment might contribute to the emergence of myocarditis, or leucopenia. Strategies for managing adverse effects are different in these conditions and are discussed accordingly.

Predictors of Bronchopulmonary Dysplasia in 625 Neonates with Respiratory Distress Syndrome

OBJECTIVE

This study was designed to investigate the predictors of bronchopulmonary dysplasia in neonates with respiratory distress syndrome.

METHODS

This was a single-center retrospective cohort study conducted between 1 January 2015 and 31 December 2020. A total of 625 neonates with respiratory distress syndrome (RDS) were enrolled. Demographic data, clinical presentations, complications and related treatment information were collected and analyzed. We used bivariate and multivariate logistic-regression analyses to determine significant predictors of bronchopulmonary dysplasia (BPD) in RDS neonates.

RESULTS

In these 625 neonates, 102 (16.3%) of them developed BPD. Bivariate analysis and multivariate logistic-regression analyses revealed that birthweight, gestational age under 32 weeks, duration of oxygen therapy over 10 days, asphyxia, patent ductus arteriosus, transfusion of red blood cells (packed red blood cells) and surfactant use were significantly associated with the development of BPD.

CONCLUSION

Birthweight, gestational age <32 weeks, total duration of oxygen therapy >10 days, asphyxia, patent ductus arteriosus, need for red blood cell infusion, and the use of pulmonary surfactant were important predictors of BPD in neonates with RDS.

Recognition and management of clozapine adverse effects: A systematic review and qualitative synthesis

OBJECTIVE

Clozapine is substantially underutilized in most countries and clinician factors including lack of knowledge and concerns about adverse drug effects (ADEs) contribute strongly to treatment reluctance. The aim of this systematic review was to provide clinicians with a comprehensive information source regarding clozapine ADEs.

METHODS

PubMed and Embase databases were searched for English language reviews concerned with clozapine ADEs; publications identified by the automated search were manually searched for additional relevant citations. Following exclusion of redundant and irrelevant reports, pertinent information was summarized in evidence tables corresponding to each of six major ADE domains; two authors reviewed all citations for each ADE domain and summarized their content by consensus in the corresponding evidence table. This study was conducted in accordance with PRISMA principles.

RESULTS

Primary and secondary searches identified a total of 305 unique reports, of which 152 were included in the qualitative synthesis. Most clozapine ADEs emerge within 3 months, and almost all appear within 6 months, after initiation. Notable exceptions are weight gain, diabetic ketoacidosis (DKA), severe clozapine-induced gastrointestinal hypomotility (CIGH), clozapine-induced cardiomyopathy (CICM), seizures, and clozapine-induced neutropenia (CIN). Most clozapine ADEs subside gradually or respond to dose reduction; those that prompt discontinuation generally do not preclude rechallenge. Rechallenge is generally inadvisable for clozapine-induced myocarditis (CIM), CICM, and clozapine-induced agranulocytosis (CIA). Clozapine plasma levels >600-1000 μg/L appear more likely to cause certain ADEs (e.g., seizures) and, although there is no clear toxicity threshold, risk/benefit ratios are generally unfavorable above 1000 μg/L.

CONCLUSION

Clozapine ADEs rarely require discontinuation.

Sex-dependent effects of long-term clozapine or haloperidol medication on red blood cells and liver iron metabolism in Sprague Dawley rats as a model of metabolic syndrome

BACKGROUND

Patients with liver diseases often have some form of anemia. Hematological dyscrasias are known side effects of antipsychotic drug medication and the occurrence of agranulocytosis under clozapine is well described. However, the sex-dependent impact of clozapine and haloperidol on erythrocytes and symptoms like anemia, and its association with hepatic iron metabolism has not yet been completely clarified. Therefore, in the present study, we investigated the effect of both antipsychotic drugs on blood parameters and iron metabolism in the liver of male and female Sprague Dawley rats.

METHODS

After puberty, rats were treated orally with haloperidol or clozapine for 12 weeks. Blood count parameters, serum ferritin, and liver transferrin bound iron were determined by automated counter. Hemosiderin (Fe³⁺) was detected in liver sections by Perl's Prussian blue staining. Liver hemoxygenase (HO-1), 5'aminolevulinate synthase (ALAS1), hepcidin, heme-regulated inhibitor (HRI), cytochrome P4501A1 (CYP1A1) and 1A2 (CYP1A2) were determined by Western blotting.

RESULTS

We found anemia with decreased erythrocyte counts, associated with lower hemoglobin and hematocrit, in females with haloperidol treatment. Males with clozapine medication showed reduced hemoglobin and increased red cell distribution width (RDW) without changes in erythrocyte numbers. High levels of hepatic hemosiderin were found in the female clozapine and haloperidol medicated groups. Liver HRI was significantly elevated in male clozapine medicated rats. CYP1A2 was significantly reduced in clozapine medicated females.

CONCLUSIONS

The characteristics of anemia under haloperidol and clozapine medication depend on the administered antipsychotic drug and on sex. We suggest that anemia in rats under antipsychotic drug medication is a sign of an underlying liver injury induced by the drugs. Changing hepatic iron metabolism under clozapine and haloperidol may help to reduce these effects of liver diseases.

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.

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

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

Therapeutic drug monitoring of clozapine in adults with schizophrenia: a review of challenges and strategies

INTRODUCTION

Clozapine (CLZ) is the superior drug in treatment of schizophrenia. Serum concentration of CLZ is associated with clinical response and dose-dependents side effects, where generalized tonic-clonic seizures are most critical. Thus, therapeutic drug monitoring (TDM) of CLZ may guide individual dosing to reach target exposure and prevent dose-dependent side effects. However, current TDM methods are not capable of predicting the risk of agranulocytosis, which is a dose-independent side effect restricting use of CLZ to treatment-resistant schizophrenia (TRS).

AREAS COVERED

The article provides an overview of clinical, pharmacological, and toxicological aspects of CLZ, and the role of TDM as a tool for dose titration and follow-up in patients with TRS. Main focus is on current challenges and strategies in CLZ TDM, including future perspectives on potential identification/analysis of CLZ metabolite biomarkers reflecting the risk of granulocyte toxicity.

EXPERT OPINION

The association between CLZ serum concentration, clinical response and risk of seizures is indisputable. TDM should therefore always guide CLZ dose titration. Development of advanced TDM methods, including biomarkers predicting the risk of granulocyte toxicity might extend TDM to be a tool for deciding which patients that can be treated safely with CLZ, potentially increasing its utility beyond TRS.

Challenges in Prescribing Clozapine in the Era of COVID-19: A Review Focused on Immunological Implications

The global COVID-19 pandemic has disrupted every aspect of the healthcare system. Apart from the issues surrounding COVID-19 itself, care for existing patients has met many challenges. One such challenge is caring for patients who are on clozapine treatment and have been confirmed positive for COVID-19. Schizophrenia has been considered to have a deep connection with the immune system, and clozapine can induce further changes in this system. COVID-19 can ravage the compromised immune system and aggravate tissue damage. The intricate relations between schizophrenia, clozapine, and COVID-19 make it difficult to predict the clinical course of COVID-19 in clozapine-treated patients. However, the rigid prohibition on using clozapine if COVID-19 is confirmed may harm patients. Patients who have to use clozapine are often refractory cases with no alternatives. Therefore, the decision to maintain or stop clozapine must be made after a comprehensive review of the patient’s unique situation. To do this, theoretical and practical issues surrounding the use of clozapine in COVID-19 should be reviewed and discussed. In this review, we gather useful information surrounding this issue and present an overview. Focusing on the immune system, various theoretical possibilities that could arise from schizophrenia, clozapine, and COVID-19 were carefully examined, and practical checklists for the care of these patients were explored. It is hoped that this review will convince many clinicians to pay attention to this momentous issue and facilitate more active sharing of clinical experiences.

Use of olanzapine compared with clozapine for treatment-resistant schizophrenia in a real-world setting: nationwide register-based study

BACKGROUND

Clozapine is generally considered as the treatment of choice for patients with treatment-resistant schizophrenia (TRS). However, its superiority has recently been questioned because olanzapine has been suggested as non-inferior to clozapine in its effectiveness.

AIMS

We aimed to investigate the current status of clozapine prescriptions to identify any disparity between clinical guidelines and real-world practices.

METHOD

In this study, we utilised the Health Insurance Review Agency database in the Republic of Korea to investigate the real-world effectiveness of clozapine for patients with TRS. We compared differences in patient variables before and after clozapine administration, and we also performed survival analyses for both psychiatric admissions and emergency room visits among patients who used clozapine or olanzapine.

RESULTS

This study investigated an incident cohort of 64 442 patients, and 2338 patients have been prescribed clozapine. Of these, 998 patients had TRS. In survival analysis, clozapine showed a worse survival rate for psychiatric admissions than olanzapine (hazard ratio 0.615). We also identified that clinicians tended to try a number of antipsychotics, as recommended, before starting patients on clozapine.

CONCLUSIONS

In conclusion, we found that olanzapine led to higher survival rates for psychiatric admissions than clozapine. Thus, considering the risk of serious adverse effects, clozapine may be used conservatively. Considering several studies advocating superior efficacy of clozapine, further studies with extensive data are recommended.

Second-generation antipsychotics induce cardiotoxicity by disrupting spliceosome signaling: Implications from proteomic and transcriptomic analyses

Second-generation antipsychotics (SGAs) are first-line drugs that are prescribed for mental disorders in clinic. Severe cardiotoxicity has been widely reported and thus limits their clinical application. This study aimed to identify the common mechanism underlying SGAs-induced cardiotoxicity using dual-omics analyses. Balb/C mice were intraperitoneally injected with two representative SGAs, olanzapine (2.5 mg/kg) and clozapine (25 mg/kg), at clinically comparable doses for 0, 7, 14 and 21 days. Our results showed that both SGAs induced cardiomyocyte degeneration, inflammation infiltration, and cardiac fibrosis, all of which worsened with time. Proteomic analysis revelaed that 22 differentially expressed (DE) proteins overlapped in olanzapine and clozapine-treated hearts. These proteins were significantly enriched in muscle contraction, amino acid metabolism and spliceosomal assembly by GO term analysis and spliceosome signaling was among the top enriched pathways by KEGG analysis. Among the 22 DE proteins, three spliceosome signal proteins were validated in a dynamic detection, and their expression significantly correlated with the extent of SGAs-induced cardiac fibrosis. Following the spliceosome signaling dysregulation, RNA sequencing revealed that alternative splicing events in the mouse hearts were markedly enhanced by SGAs treatments, and the production of vast transcript variants resulted in dysregulation of multiple pathways that are critical for cardiomyocytes adaptation and cardiac remodeling. Pladienolide B, a specific inhibitor of mRNA splicing, successfully corrected SGAs-induced alternative splicing and significantly attenuated the secretion of pro-inflammatory factors and cell deaths induced by SGAs exposure. Our study concluded that the spliceosome signaling was a common pathway driving SGAs cardiotoxicity. Pharmacological inhibition of the spliceosome signaling represents a novel therapeutic strategy against SGAs cardiotoxicity.

Risk mitigation with the use of clozapine - Quo vadimus

The risk of neutropenia decreases significantly after the first year of clozapine initiation, and indefinite hematological monitoring is increasingly questioned. Despite comparable risks of neutropenia, the guidelines for antithyroid drugs - carbimazole and propylthiouracil do not recommend routine hematological monitoring. Assuming a similar pathogenic mechanism, data from antithyroid drugs indicate that neutropenia develops rapidly, and indefinite hematological monitoring misses a large majority of cases in the pre-symptomatic phase. Hence, a more pragmatic strategy of intensive hematological monitoring in the first year of clozapine initiation followed by selective haematological monitoring in case of febrile illnesses or pharyngitis needs to be explored.

Evolving Role of Pharmacogenetic Biomarkers to Predict Drug-Induced Hematological Disorders

ABSTRACT

Drug-induced hematological disorders constitute up to 30% of all blood dyscrasias seen in the clinic. Hematologic toxicity from drugs may range from life-threatening marrow aplasia, agranulocytosis, hemolysis, thrombosis to mild leukopenia, and thrombocytopenia. Pathophysiologic mechanisms underlying these disorders vary from an extension of the pharmacological effect of the drug to idiosyncratic and immune-mediated reactions. Predicting these reactions is often difficult, and this makes clinical decision-making challenging. Evidence supporting the role of pharmacogenomics in the management of these disorders in clinical practice is rapidly evolving. Despite the Clinical Pharmacology Implementation Consortium and Pharmacogenomics Knowledge Base recommendations, few tests have been incorporated into routine practice. This review aims to provide a comprehensive summary of the various drugs which are implicated for the hematological adverse events, their underlying mechanisms, and the current evidence and practical recommendations to incorporate pharmacogenomic testing in clinical care for predicting these disorders.

A COMMENTARY ON IMPROVING CLOZAPINE ACCESSIBILITY AND REDUCING TREATMENT COST

Clozapine is vastly underutilized in the United States and many other countries. The most commonly cited reason for this is the requirement for frequent blood monitoring, which continues for the duration of treatment. Despite the notoriety clozapine achieved early in its development, accumulated evidence has demonstrated that close blood monitoring beyond the first year of treatment yields minimal safety benefits. Many health care systems have relaxed clozapine blood monitoring requirements during the COVID-19 pandemic for practical reasons, and this presents an opportunity to implement permanent, long overdue changes in mandated monitoring that reflect what has been learned about the real risk for blood dyscrasias with clozapine.

Protection of clozapine-induced oxidative stress and mitochondrial dysfunction by kaempferol in rat cardiomyocytes

Clozapine (CLZ) is unusually efficient in psychotic diseases. Nonetheless, its use is confined due to potentially life-threatening adverse events, including cardiotoxicity. Since the cardiotoxicity of CLZ is mediated through the generation of active metabolites, free radical, and inflammation. Here, we tested this hypothesis that kaempferol (KP) as antioxidant and anti-inflammatory agent could attenuate CLZ-induced mitochondrial/lysosomal and oxidative damages in rat ventricular cardiomyocytes. Rat ventricular cardiomyocytes were isolated by collagenase perfusion. Then isolated cardiomyocytes were simultaneously treated with different concentrations of KP (10, 20, and 50 μM) and CLZ (50 μM) for 4 h at 37°C. After 4 h of incubation, using by flow cytometry and biochemical evaluations, the parameters of cellular toxicity including: cell viability, reactive oxygen species (ROS) formation, mitochondria membrane potential (ΔΨm) collapse, lysosomal membrane integrity, malondialdehyde, and oxidized/reduced glutathione were analyzed. The results showed that CLZ (50 μM) induced a significant increase in cytotoxicity, ROS formation, mitochondrial membrane potential collapse, lipid peroxidation, and oxidative stress while KP reverted the above toxic effect of CLZ on isolated cardiomyocytes. Our data suggest that KP prevents and reverses CLZ-induced oxidative and mitochondrial/lysosomal damages in isolated cardiomyocytes, providing an experimental basis for clinical treatment on CLZ-induced cardiotoxicity.

Influencing Factors of Hospital-Acquired Pneumonia Infection in the Middle-Aged and Elderly Patients With Schizophrenia

Introduction: Pneumonia is an important cause of death in patients with schizophrenia. It is critical to understand the risk factors of hospital-acquired pneumonia (HAP) and determine prevention strategies to reduce HAP. The aim of this study is to elucidate the risk factors for HAP in the middle-aged and elderly hospitalized patients with schizophrenia. Methods: We retrospectively reviewed the medical records of 2,617 the middle-aged and elderly patients (age ≥ 50) with schizophrenia who were admitted for the first time to a large-scale psychiatric hospital between 2016 and 2020. The factors related to the incidence of HAP in patients were analyzed, including personal characteristics, antipsychotics, and non-antipsychotics. Results: The HAP infection rate of hospitalized the middle-aged and elderly patients with schizophrenia was 7.8%. Chi-square analyses showed that older age, male, and ≥60 days of hospitalization were risk factors for HAP infection (χ² = 94.272, p < 0.001; χ² = 22.110, p < 0.001; χ² = 8.402, p = 0.004). Multivariate logistic regression showed that quetiapine, clozapine, and olanzapine significantly increased the incidence of HAP (OR = 1.56, 95% CI = 1.05-2.32, p = 0.029; OR = 1.81, 95% CI = 1.26-2.60, p = 0.001; OR = 1.68, 95% CI = 1.16-2.42, p = 0.006). Antipsychotic drugs combined with aceglutamide had an effect on HAP (OR = 2.19, 95% CI = 1.38-3.47, p = 0.001). Conclusion: The high HAP infection rate in hospitalized the middle-aged and elderly patients with schizophrenia may be related to the increase of age and the use of antipsychotic drugs. The types and dosages of antipsychotic drugs should be minimized while paying attention to the mental symptoms of patients.

The Duffy-null genotype and risk of infection

Many medical treatments, from oncology to psychiatry, can lower white blood cell counts and thus access to these treatments can be restricted to individuals with normal levels of white blood cells, principally in order to minimize risk of serious infection. This adversely affects individuals of African or Middle Eastern ancestries who have on average a reduced number of circulating white blood cells, because of the Duffy-null (CC) genotype at rs2814778 in the ACKR1 gene. Here, we investigate whether the Duffy-null genotype is associated with the risk of infection using the UK Biobank sample and the iPSYCH Danish case-cohort study, two population-based samples from different countries and age ranges. We found that a high proportion of those with the Duffy-null genotype (21%) had a neutrophil count below the threshold often used as a cut-off for access to relevant treatments, compared with 1% of those with the TC/TT genotype. In addition we found that despite its strong association with lower average neutrophil counts, the Duffy-null genotype was not associated with an increased risk of infection, viral or bacterial. These results have widespread implications for the clinical treatment of individuals of African ancestry and indicate that neutrophil thresholds to access treatments could be lowered in individuals with the Duffy-null genotype without an increased risk of infection.

Acute Iatrogenic Agranulocytosis: A Rare and Dire Case of an Adverse Drug Reaction to Be Aware

Background

Iatrogenic agranulocytosis (IA), by nonchemotherapeutic drugs, is a rare adverse event, resulting in a neutrophil count under 0.5 × 10⁹ cells/L with fever or other suggestive signs of infection.

Methods

This paper discusses the possible mechanisms responsible for agranulocytosis induced by nonchemotherapeutic drugs. It also describes three cases as well as potential ways to handle such iatrogenic situations.

Conclusion

Neutropenia under 0.1 × 10⁹ cells/L predispose patients to potentially fatal infections. Empiric broad-spectrum antibiotic and hematopoietic growth factors may be helpful in shortening hospitalization and prevent further infectious complications. Not all drugs associated with IA require frequent hematological monitoring, except medications such as clozapine, ticlopidine, and antithyroids.

Clozapine: An Updated Overview of Pharmacogenetic Biomarkers, Risks, and Safety-Particularities in the Context of COVID-19

BACKGROUND

clozapine (CLZ) use is precarious due to its neurological, cardiovascular, and hematological side effects; however, it is the gold standard in therapy-resistant schizophrenia (TRS) in adults and is underused.

OBJECTIVE

to examine the most recent CLZ data on (a) side effects concerning (b) recent pharmacological mechanisms, (c) therapy benefits, and (d) the particularities of the COVID-19 pandemic.

DATA SOURCES

a search was performed in two databases (PubMed and Web of Science) using the specific keywords "clozapine" and "schizophrenia", "side effects", "agranulocytosis", "TRS", or "bipolar affective disorder (BAF)" for the last ten years.

STUDY ELIGIBILITY CRITERIA

clinical trials on adults with acute symptoms of schizophrenia or related disorders.

RESULTS

we selected 37 studies, randomized controlled trials (RCTs), and clinical case series (CCS), centered on six main topics in the search area: (a) CLZ in schizophrenia, (b) CLZ in bipolar disorder, (c) side effects during the clozapine therapy, (d) CLZ in pregnancy, (e) CLZ in early-onset schizophrenia, and (f) CLZ therapy and COVID-19 infection.

LIMITATIONS

we considered RCTs and CCS from two databases, limited to the search topics. Conclusions and implications of key findings: (a) clozapine doses should be personalized for each patient based on pharmacogenetics testing when available; the genetic vulnerability postulates predictors of adverse reactions' severity; patients with a lower genetic risk could have less frequent hematological monitoring; (b) a CLZ-associated risk of pulmonary embolism imposes prophylactic measures for venous thromboembolism; (c) convulsive episodes are not an indication for stopping treatment; the plasma concentration of clozapine is a better side effect predictor than the dosage; (d) COVID-19 infection may enhance clozapine toxicity, generating an increased risk of pneumonia. Therapy must be continued with the proper monitoring of the white blood count, and the clozapine dose decreased by half until three days after the fever breaks; psychiatrists and healthcare providers must act together.

Safety of Psychotropic Medications in People With COVID-19: Evidence Review and Practical Recommendations

(Reprinted with permission from the BMC Medicine (2020) 18:215).

Treatment Capacity and Clinical Outcomes for Patients With Schizophrenia Who Were Treated With Electroconvulsive Therapy: A Retrospective Cohort Study

BACKGROUND

Patients with schizophrenia are often found incapable to consent to psychiatric treatment. We evaluated clinical outcomes for incapable and capable patients with schizophrenia treated with electroconvulsive therapy (ECT).

METHODS

We conducted a chart review of all inpatients treated with an acute course of ECT between 2010 and 2018 at the Centre for Addiction and Mental Health, Toronto, Canada. Short-term outcomes included treatment response and cognitive impairment. We assessed whether incapable patients regained the capacity to consent to treatment. Long-term outcomes included readmissions and subsequent courses of acute or maintenance ECT.

RESULTS

A total of 159 (67%) incapable and 79 (33%) capable patients were included. Patients experienced treatment response (incapable, n = 108, 67.9%; capable, n = 52, 65.8%; P = .771) and few experienced cognitive impairment (incapable, n = 21, 13.2%; capable, n = 19, 24.1%; P = .043). A minority of patients were treated with a subsequent course of acute ECT (incapable, n = 46, 28.9%; capable, n = 16, 20.3%; P = .162). Incapable patients were more likely to be treated with maintenance ECT for at least 6 months (incapable, n = 46, 28.9%; capable, n = 13, 16.5%; P = .039). Both groups had similar readmission rates (incapable, n = 70, 44.0%; capable, n = 35, 44.3%; P = 1.000). Eight (5.0%) incapable patients regained capacity and 7 consented to further treatment.

CONCLUSIONS

Irrespective of treatment capacity, the majority of patients demonstrated clinical improvement. Incapable patients experienced less cognitive side effects when compared with capable patients, though they had fewer treatments overall. This study informs clinicians, patients, and substitute decision-makers about the outcomes and challenges of ECT in patients with schizophrenia.

Characterization of Clozapine-Responsive Human T Cells

Use of the atypical antipsychotic clozapine is associated with life-threatening agranulocytosis. The delayed onset and the association with HLA variants are characteristic of an immunological mechanism. The objective of this study was to generate clozapine-specific T cell clones (TCC) and characterize pathways of T cell activation and cross-reactivity with clozapine metabolites and olanzapine. TCC were established and characterized by culturing PBMCs from healthy donors and patients with a history of clozapine-induced agranulocytosis. Modeling was used to explore the drug-HLA binding interaction. Global TCC protein changes were profiled by mass spectrometry. Six well-growing clozapine-responsive CD4⁺ and CD8⁺ TCC were used for experiments; activation of TCC required APC, with clozapine interacting directly at therapeutic concentrations with several HLA-DR molecules. TCC were also activated with N-desmethylclozapine and olanzapine at supratherapeutic concentrations. Marked changes in TCC protein expression profiles were observed when clozapine treatment was compared with olanzapine and the medium control. Docking of the compounds into the HLA-DRB1*15:01 and HLA-DRB1*04:01 binding clefts revealed that clozapine and olanzapine bind in a similar conformation to the P4-P6 peptide binding pockets, whereas clozapine N-oxide, which did not activate the TCC, bound in a different conformation. TCC secreted Th1, Th2, and Th22 cytokines and effector molecules and expressed TCR Vβ 5.1, 16, 20, and 22 as well as chemokine receptors CXCR3, CCR6, CCR4, and CCR9. Collectively, these data show that clozapine interacts at therapeutic concentrations with HLA-DR molecules and activates human CD4⁺ T cells. Olanzapine only activates TCC at supratherapeutic concentrations.

Metabolite Patterns in Human Myeloid Hematopoiesis Result from Lineage-Dependent Active Metabolic Pathways

Assessment of hematotoxicity from environmental or xenobiotic compounds is of notable interest and is frequently assessed via the colony forming unit (CFU) assay. Identification of the mode of action of single compounds is of further interest, as this often enables transfer of results across different tissues and compounds. Metabolomics displays one promising approach for such identification, nevertheless, suitability with current protocols is restricted. Here, we combined a hematopoietic stem and progenitor cell (HSPC) expansion approach with distinct lineage differentiations, resulting in formation of erythrocytes, dendritic cells and neutrophils. We examined the unique combination of pathway activity in glycolysis, glutaminolysis, polyamine synthesis, fatty acid oxidation and synthesis, as well as glycerophospholipid and sphingolipid metabolism. We further assessed their interconnections and essentialness for each lineage formation. By this, we provide further insights into active metabolic pathways during the differentiation of HSPC into different lineages, enabling profound understanding of possible metabolic changes in each lineage caused by exogenous compounds.

Safety of psychotropic medications in people with COVID-19: evidence review and practical recommendations

BACKGROUND

The novel coronavirus pandemic calls for a rapid adaptation of conventional medical practices to meet the evolving needs of such vulnerable patients. People with coronavirus disease (COVID-19) may frequently require treatment with psychotropic medications, but are at the same time at higher risk for safety issues because of the complex underlying medical condition and the potential interaction with medical treatments.

METHODS

In order to produce evidence-based practical recommendations on the optimal management of psychotropic medications in people with COVID-19, an international, multi-disciplinary working group was established. The methodology of the WHO Rapid Advice Guidelines in the context of a public health emergency and the principles of the AGREE statement were followed. Available evidence informing on the risk of respiratory, cardiovascular, infective, hemostatic, and consciousness alterations related to the use of psychotropic medications, and drug-drug interactions between psychotropic and medical treatments used in people with COVID-19, was reviewed and discussed by the working group.

RESULTS

All classes of psychotropic medications showed potentially relevant safety risks for people with COVID-19. A set of practical recommendations was drawn in order to inform frontline clinicians on the assessment of the anticipated risk of psychotropic-related unfavorable events, and the possible actions to take in order to effectively manage this risk, such as when it is appropriate to avoid, withdraw, switch, or adjust the dose of the medication.

CONCLUSIONS

The present evidence-based recommendations will improve the quality of psychiatric care in people with COVID-19, allowing an appropriate management of the medical condition without worsening the psychiatric condition and vice versa.

Risk Factors for Relapse of Childhood B Cell Acute Lymphoblastic Leukemia

Background

B cell acute lymphoblastic leukemia (B-ALL) is the most common type of ALL. This study aimed to explore risk factors for relapse of childhood B-ALL.

Material/Methods

Total of 102 pediatric B-ALL patients were included in this study. B-ALL patients were divided into a relapse group and a non-relapse group. Chemotherapy-induced agranulocytosis time, fusion gene, and minimal residual disease (MRD) were assessed. White blood cell (WBC) count in peripheral blood and risk stratification were evaluated in newly-diagnosed patients. Kaplan-Meier plots were used to evaluate the correlation between risk factors and relapse rates. Multivariate analysis was performed with Cox proportional hazard model to estimate relative risk (RR), 95% confidence interval (95% CI), and hazard ratio (HR). Finally, 99 cases of B-ALL were included in this study.

Results

There were significant differences between the relapse group and the non-relapse group in age (p=0.004), chemotherapy-induced agranulocytopenia (p=0.001), WBC count in peripheral blood of newly diagnosed patients (p=0.016), risk stratification (p=0.000), and MRD at 12^th week (p=0.007). Age over 10 years, high-risk stratification, long period of agranulocytopenia, higher WBC counts, and MRD more than 10⁻⁴ were correlated with higher B-ALL relapse rate (p<0.05). Multivariate analysis showed significantly higher relapse rates for age ≥10 years, high-risk stratification, and MRD at 12^th week >10⁻⁴, with RR (95% CI) of 4.001 (1.005–15.930), 4.964 (1.050–23.456), and 4.646 (1.383–15.614), respectively.

Conclusions

Agranulocytopenia ≤7 days, peripheral blood WBC >100×10⁹/L, and MRD at 33^rd day >10⁻⁴ were associated with B-ALL relapse. Age ≥10 years, high-risk stratification, and MRD at 12^th week >10⁻⁴ were independent risk factors for relapse.

Identification of a novel polymorphism associated with reduced clozapine concentration in schizophrenia patients-a genome-wide association study adjusting for smoking habits

Clozapine (CLZ) is the superior antipsychotic drug for treatment of schizophrenia, but exhibits an extensive interpatient pharmacokinetic variability. Here, we conducted a genome-wide association study (GWAS) of CLZ serum concentration adjusting for known smoking habits, which is a major nongenetic factor reducing CLZ levels. The study included 484 patients with 10,283 steady-state serum concentrations of CLZ and N-desmethylclozapine, prescribed dosing, co-medications and known smoking habits (n = 422; 9284 serum samples) from a therapeutic drug monitoring (TDM) service. The GWAS analyses were performed with and without smoking habits as covariate, where possible hits were assessed in relation to the target CLZ concentration range applied in the TDM service (300-2500 nmol/L). The smoking-independent analysis of N-desmethylclozapine serum concentration and the CLZ-to-N-desmethylclozapine ratio replicated the previously identified locus on chromosome 4. After adjusting for smoking habits in patients confirmed as 'smokers' (61%) or 'nonsmokers' (39%), a novel variant (rs28379954; minor T>C allele frequency 4.1%; 7.6% CT carriers in the population) within the gene encoding the nuclear factor 1 B-type (NFIB) was significantly associated with reduced CLZ serum concentration (p = 1.68 × 10-8, beta = -0.376; explained variance 7.63%). There was no significant association between rs28379954 and N-desmethylclozapine concentration in the GWAS analysis (p = 5.63 × 10-5). The fraction of CLZ TDM samples below 300 nmol/L was significantly higher in carriers vs. noncarriers of the rs28379954 minor C allele [12.0% (95% CI: 9.4-14.7) vs. 6.2% (95% CI: 5.7-6.8), p < 0.001]. We identified a novel variant in the NFIB gene associated with reduced CLZ levels and increased risk of subtherapeutic serum concentrations. This warrants testing of clinical relevance of screening for this gene variant, and also experimental studies to investigate the biological mechanisms of NFIB involvement in CLZ pharmacokinetics.

A Rational Use of Clozapine Based on Adverse Drug Reactions, Pharmacokinetics, and Clinical Pharmacopsychology

Using Richardson and Davidson's model and the sciences of pharmacokinetics and clinical pharmacopsychology, this article reviewed the: (1) poor life expectancy associated with treatment-resistant schizophrenia (TRS), which may be improved in patients who adhere to clozapine; (2) findings that clozapine is the best treatment for TRS (according to efficacy, effectiveness and well-being); and (3) potential for clozapine to cause vulnerabilities, including potentially lethal adverse drug reactions such as agranulocytosis, pneumonia, and myocarditis. Rational use requires: (1) modification of the clozapine package insert worldwide to include lower doses for Asians and to avoid the lethality associated with pneumonia, (2) the use of clozapine levels for personalizing dosing, and (3) the use of slow and personalized titration. This may make clozapine as safe as possible and contribute to increased life expectancy and well-being. In the absence of data on COVID-19 in clozapine patients, clozapine possibly impairs immunological mechanisms and may increase pneumonia risk in infected patients. Psychiatrists should call their clozapine patients and families and explain to them that if the patient develops fever or flu-like symptoms, the psychiatrist should be called and should consider halving the clozapine dose. If the patient is hospitalized with pneumonia, the treating physician needs to assess for symptoms of clozapine intoxication since halving the dose may not be enough for all patients; consider decreasing it to one-third or even stopping it. Once the signs of inflammation and fever have disappeared, the clozapine dose can be slowly increased to the prior dosage level.

G-CSF mediated neutrophil augmentation in a unique case of comorbid idiopathic Parkinson's disease and treatment-resistant schizophrenia on clozapine

Treatment of psychosis in Parkinson's disease (PD) is challenging; pharmacological options are limited, with clozapine considered most effective. The risk of agranulocytosis restricts the use of clozapine, but, where this occurs, cautious re-challenge with granulocyte stimulating factor can be successful. We present a unique case of a patient who developed early-onset PD on a background of antecedent treatment-resistant schizophrenia, who had been treated effectively with clozapine for over 15 years with no adverse events. However, during a hospital admission intended to optimise her Parkinsonian medications, she developed persistent neutropenia necessitating clozapine discontinuation. Numerous attempts to re-challenge with clozapine failed until augmentation with lithium and G-CSF was trialled. Two doses of G-CSF led to a sustained increase in the neutrophil count, allowing the continuation of clozapine therapy in the 1 year of follow up. This illustrates the potential for G-CSF to be used to facilitate clozapine use in a patient population not described previously. Neutrophil augmentation allowed the sustained continuation of this effective therapy, treating her psychotic symptoms without detriment to her movement disorder. We suggest that G-CSF might be considered as a treatment option in other cases where clozapine-associated neutropenia obstructs its use.

Clozapine and desmethylclozapine: correlation with neutrophils and leucocytes counting in Mexican patients with schizophrenia

PURPOSE

The aim of present study is to measure plasma clozapine (CLZ) and N-desmethyl clozapine (DMC) as biomarkers to correlate drug concentrations with the appearance of preclinical adverse hematic effects.

METHODS

A high-performance liquid chromatographic method, using a diode-array (ultraviolet) detector, was validated to obtain reliable concentrations of CLZ and DMC, its main metabolite, in plasma of 41 schizophrenic patients taking CLZ. Blood neutrophils and leucocytes counting were concurrently assessed as a proxy to subclinical adverse reactions.

RESULTS

The analytical method employed was linear, reproducible, and stable to measure concentrations of CLZ between 30 and 1000 ng/mL, while 12.5-560 ng/mL of the metabolite. The method allowed us to correlate CLZ plasma concentrations, the time taking CLZ and CLZ dose as determinants of neutrophils' counting with a R² = 0.447, using a multiple regression analysis model. Likewise, the correlation of leucocyte counting vs CLZ plasma levels and CLZ time, showed a R² = 0.461. DMC correlated significantly with both neutrophils and leucocytes counting, but was excluded from the regression when CLZ concentration was included in the model. Finally, no other hematological adverse reactions were recorded. One patient presented a cardiovascular complication. The negative correlation between clozapine and neutrophil count observed in patients, suggest that CLZ itself, but not DMC, could be related to hematologic side-effects.

CONCLUSION

The findings of this study, demonstrate for the first time, that plasma levels of CLZ and time taking the drug are independent determinants of blood neutrophils and leucocytes, so the monitoring of plasma CLZ may be useful in the clinic practice to determine safe dosing of the drug.

Agranulocytosis attributed to metamizole: An analysis of spontaneous reports in EudraVigilance 1985-2017

Despite ongoing debates about its safety, the use of metamizole (dipyrone) is still increasing in many countries. In this study, we analysed spontaneous reports of suspected metamizole-associated agranulocytosis recorded in EudraVigilance database from 1985 to 2017 with regard to patient and treatment characteristics as well as fatal vs non-fatal outcomes and compared these findings among countries. A total of 1448 reports from 31 different countries were included (Germany 42.0%; Spain 29.6%; Switzerland 13.1%; other countries 15.3%). Mean age of patients was 53.6 years (63.4% females). Differences among countries were observed, for example with respect to patient age, route of administration and daily doses. Overall, median time between starting metamizole and developing an agranulocytosis was 13 days with 34.7% of cases occurring up to 7 days. This time was much shorter in patients who had already received metamizole before (median: 6 vs 15 days). About 16% of cases ended fatally. Patients with fatal outcomes were older and more often had also received methotrexate compared to those with non-fatal outcomes. When adjusting for age and sex in a multivariable logistic regression, methotrexate was associated with an increased risk of fatal outcomes (odds ratio: 5.18; 95% confidence interval: 3.06-8.78). In conclusion, metamizole-associated agranulocytosis is still a life-threatening condition, especially in the elderly and those also receiving methotrexate. As agranulocytosis can develop weeks after last administration and independently of dose and duration of treatment, prescribers and patients should be aware of its signs and symptoms.

State of Art of Idiosyncratic Drug-Induced Neutropenia or Agranulocytosis, with a Focus on Biotherapies

INTRODUCTION

Idiosyncratic drug-induced neutropenia and agranulocytosis is seldom discussed in the literature, especially for new drugs such as biotherapies outside the context of oncology. In the present paper, we report and discuss the clinical data and management of this relatively rare disorder, with a focus on biotherapies used in autoimmune and auto-inflammatory diseases.

MATERIALS AND METHODS

A review of the literature was carried out using the PubMed database of the US National Library of Medicine. We searched for articles published between January 2010 and May 2019 using the following key words or associations: "drug-induced neutropenia", "drug-induced agranulocytosis", and "idiosyncratic agranulocytosis". We included specific searches on several biotherapies used outside the context of oncology, including: tumor necrosis factor (TNF)-alpha inhibitors, anti-CD20 agents, anti-C52 agents, interleukin (IL) 6 inhibitors, IL 1 inhibitors, and B-cell activating factor inhibitor.

RESULTS

Idiosyncratic neutropenia remains a potentially serious adverse event due to the frequency of severe sepsis with severe deep tissue infections (e.g., pneumonia), septicemia, and septic shock in approximately two-thirds of all hospitalized patients with grade 3 or 4 neutropenia (neutrophil count (NC) ≤ 0.5 × 109/L and ≤ 0.1 × 109/L, respectively). Over the last 20 years, several drugs have been strongly associated with the occurrence of idiosyncratic neutropenia, including antithyroid drugs, ticlopidine, clozapine, sulfasalazine, antibiotics such as trimethoprim-sulfamethoxazole, and deferiprone. Transient grade 1-2 neutropenia (absolute blood NC between 1.5 and 0.5 × 109/L) related to biotherapy is relatively common with these drugs. An approximate 10% prevalence of such neutropenia has been reported with several of these biotherapies (e.g., TNF-alpha inhibitors, IL6 inhibitors, and anti-CD52 agents). Grade 3-4 neutropenia or agranulocytosis and clinical manifestations related to sepsis are less common, with only a few case reports to date for most biotherapies. Special mention should be made of late onset and potentially severe neutropenia, especially following anti-CD52 agent therapy. During drug therapy, several prognostic factors have been identified that may be helpful when identifying 'susceptible' patients. Older age (>65 years), septicemia or shock, renal failure, and a neutrophil count ≤0.1 × 109/L have been identified as poor prognostic factors. Idiosyncratic neutropenia should be managed depending on clinical severity, with permanent/transient discontinuation or a lower dose of the drug, switching from one drug to another of the same or another class, broad-spectrum antibiotics in cases of sepsis, and hematopoietic growth factors (particularly G-CSF).

CONCLUSION

Significant progress has been made in recent years in the field of idiosyncratic drug-induced neutropenia, leading to an improvement in their prognosis (currently, mortality rate between 5 and 10%). Clinicians must continue their efforts to improve their knowledge of these adverse events with new drugs as biotherapies.

Inhibition of Epstein-Barr Virus Lytic Reactivation by the Atypical Antipsychotic Drug Clozapine

Epstein–Barr virus (EBV), a member of the Herpesviridae family, maintains a lifelong latent infection in human B cells. Switching from the latent to the lytic phase of its lifecycle allows the virus to replicate and spread. The viral lytic cycle is induced in infected cultured cells by drugs such as sodium butyrate and azacytidine. Lytic reactivation can be inhibited by natural products and pharmaceuticals. The anticonvulsant drugs valproic acid and valpromide inhibit EBV in Burkitt lymphoma cells. Therefore, other drugs that treat neurological and psychological disorders were investigated for effects on EBV lytic reactivation. Clozapine, an atypical antipsychotic drug used to treat schizophrenia and bipolar disorder, was found to inhibit the reactivation of the EBV lytic cycle. Levels of the viral lytic genes BZLF1, BRLF1, and BMLF1 were decreased by treatment with clozapine in induced Burkitt lymphoma cells. The effects on viral gene expression were dependent on the dose of clozapine, yet cells were viable at an inhibitory concentration of clozapine. One metabolite of clozapine—desmethylclozapine—also inhibited EBV lytic reactivation, while another metabolite—clozapine-N-oxide—had no effect. These drugs may be used to study cellular pathways that control the viral lytic switch in order to develop treatments for diseases caused by EBV.

Monocytopenia in clozapine-induced agranulocytosis: insights into pathophysiology and treatment

A 26-year-old man with history of schizophrenia was admitted for neutropaenia. He was started on clozapine 3 months prior to admission. As a result he had weekly monitoring of his blood counts and on day of admission was noted to have an absolute neutrophil count (ANC) of 450 cells/μL. He was admitted for clozapine-induced agranulocytosis. Clozapine was held and the patient was started on granulocyte colony-stimulating factor (G-CSF) filgrastim and received two doses without any signs of ANC recovery. On further review, it was noted that the absolute monocyte count (AMC) was also low and tracked with the trend of ANC. We then theorised that the impact of clozapine was on a haematopoietic precursor (colony-forming unit granulocyte-macrophage, CFU-GM) which gives rise to both monocytic and myeloid lineages. Therefore, sargramostim GM-CSF was started. After two doses, the ANC and AMC started trending up and by the third dose, both counts had fully recovered. He was discharged from the hospital and there are no plans to rechallenge with clozapine. Thus, we demonstrate a case of monocytopenia accompanying clozapine-induced agranulocytosis with successful use of GM-CSF. At least in this case, the target of the clozapine injury appears to be the CFU-GM, explaining the rapid and full response to GM-CSF after lack of response to G-CSF.

Adjunctive second-generation antipsychotics for specific symptom domains of schizophrenia resistant to clozapine: A meta-analysis

A fair amount of subjects with schizophrenia do not respond to clozapine and are defined 'ultra-resistant'. In this systematic review and meta-analysis, we tested the efficacy of adjunctive second-generation antipsychotics (SGAs) for main symptom domains (positive, negative, and depressive symptoms) in individuals with clozapine-resistant schizophrenia. We searched main electronic databases till December 2017. We included twelve double-blind, randomized, placebo-controlled trials (RCTs), evaluating the efficacy of SGAs for clozapine non/partial responders. We did not find any difference between SGAs and placebo (standardized mean difference, SMD = -0.21; p = 0.170; I² = 68.0%) in improving positive symptoms. The effect size varied according to RCT duration (p = 0.025) and assessment methods (p = 0.016). Low-moderate effects of SGAs on both negative (SMD = -0.38; p = 0.005; I² = 62.7%) and depressive symptoms (SMD = -0.35; p = 0.003; I² = 4.9%), were estimated. In sum, our meta-analysis highlights the lack of efficacy of SGAs as add-on treatment for positive symptoms in clozapine-resistant schizophrenia. A small benefit of SGAs was estimated for both negative and depressive symptoms. Further RCTs are needed to establish efficacy and tolerability of SGAs or other augmentation strategies for different symptoms of clozapine-resistant schizophrenia.

Clozapine Pharmacogenetic Studies in Schizophrenia: Efficacy and Agranulocytosis

Clozapine is an efficacious atypical antipsychotic for treatment-refractory schizophrenia. Clinical response and appearance of adverse events vary among individual patients receiving clozapine, with genetic and non-genetic factors potentially contributing to individual variabilities. Pharmacogenetic studies investigate associations between genetic variants and drug efficacy and toxicity. To date, most pharmacogenetic studies of clozapine have been conducted through candidate gene approaches. A recent advance in technology made it possible to perform comprehensive genetic mapping underlying clinical phenotypes and outcomes, which allow novel findings beyond biological hypotheses based on current knowledge. In this paper, we will summarize the studies on clozapine pharmacogenetics that have extensively examined clinical response and agranulocytosis. While there is still limited evidence on clozapine efficacy, recent genome-wide studies provide further evidence of the involvement of the human leukocyte antigen (HLA) region in clozapine-induced agranulocytosis.

Neuroprotective Activity of Sitagliptin via Reduction of Neuroinflammation beyond the Incretin Effect: Focus on Alzheimer's Disease

Sitagliptin is a member of a class of drugs that inhibit dipeptidyl peptidase (DPP-4). It increases the levels of the active form of incretins such as GLP-1 (glucagon-like peptide-1) or GIP (gastric inhibitory polypeptide) and by their means positively affects glucose metabolism. It is successfully applied in the treatment of diabetes mellitus type 2. The most recent scientific reports suggest beneficial effect of sitagliptin on diseases in which neuron damage occurs. Result of experimental studies may indicate a reducing influence of sitagliptin on inflammatory response within encephalon area. Sitagliptin decreased the levels of proinflammatory factors: TNF-α (tumor necrosis factor-α), IL-6 (interleukin-6), IL-17 (interleukin-17), and CD-163 (cluster of differentiation 163), and contributed to an increase in levels of anti-inflammatory factors: IL-10 (interleukin-10) and TGF-β (transforming growth factor β). Moreover, sitagliptin demonstrated antioxidative and antiapoptotic properties by modifying glutamate and glutathione levels within the region of hippocampus in mice. It has been observed that sitagliptin decreases accumulation of β-amyloid within encephalon structures in experimental models of Alzheimer's dementia. This effect may be connected with SDF-1α (stromal cell-derived factor 1α) concentration. Administration of sitagliptin caused a significant improvement in MMSE (Mini-Mental State Examination) tests used for assessment of dementias. The paper presents potential mechanisms of sitagliptin activity in conditions connected with neuroinflammation with special emphasis on Alzheimer's disease.

Cellular Uptake of the Atypical Antipsychotic Clozapine Is a Carrier-Mediated Process

The weak base antipsychotic clozapine is the most effective medication for treating refractory schizophrenia. The brain-to-plasma concentration of unbound clozapine is greater than unity, indicating transporter-mediated uptake, which has been insufficiently studied. This is important, because it could have a significant impact on clozapine's efficacy, drug-drug interaction, and safety profile. A major limitation of clozapine's use is the risk of clozapine-induced agranulocytosis/granulocytopenia (CIAG), which is a rare but severe hematological adverse drug reaction. We first studied the uptake of clozapine into human brain endothelial cells (hCMEC/D3). Clozapine uptake into cells was consistent with a carrier-mediated process, which was time-dependent and saturable ( V_max = 3299 pmol/million cells/min, K_m = 35.9 μM). The chemical inhibitors lamotrigine, quetiapine, olanzapine, prazosin, verapamil, indatraline, and chlorpromazine reduced the uptake of clozapine by up to 95%. This could in part explain the in vivo interactions observed in rodents or humans for these compounds. An extensive set of studies utilizing transporter-overexpressing cell lines and siRNA-mediated transporter knockdown in hCMEC/D3 cells showed that clozapine was not a substrate of OCT1 (SLC22A1), OCT3 (SLC22A3), OCTN1 (SLC22A4), OCTN2 (SLC22A5), ENT1 (SLC29A1), ENT2 (SLC29A2), and ENT4/PMAT (SLC29A4). In a recent genome-wide analysis, the hepatic uptake transporters SLCO1B1 (OATP1B1) and SLCO1B3 (OATP1B3) were identified as additional candidate transporters. We therefore also investigated clozapine transport into OATP1B-transfected cells and found that clozapine was neither a substrate nor an inhibitor of OATP1B1 and OATP1B3. In summary, we have identified a carrier-mediated process for clozapine uptake into brain, which may be partly responsible for clozapine's high unbound accumulation in the brain and its drug-drug interaction profile. Cellular clozapine uptake is independent from currently known drug transporters, and thus, molecular identification of the clozapine transporter will help to understand clozapine's efficacy and safety profile.