Haematological toxicity of clozapine and some other drugs used in psychiatry

Risk of clozapine-associated agranulocytosis and mandatory white blood cell monitoring: Can the regulations be relaxed?

After the introduction of clozapine eight Finnish patients died after developing agranulocytosis. Clozapine was withdrawn from the market and only reintroduced with strict mandatory white blood cell monitoring as long as treatment lasts and thresholds at which clozapine must be discontinued definitively. The fear of agranulocytosis and the need for intensive blood monitoring is the single most important barrier for prescribers and patients alike and leads to underprescription of the only effective and approved medication for treatment-resistant schizophrenia. We summarize evidence that the risk of agranulocytosis is smaller than perceived at the time of reintroduction, is concentrated in the first 18 weeks of treatment, is not greater than with other antipsychotics thereafter and that frequent blood monitoring has not demonstrably decreased the rate of agranulocytosis. Therefore we propose 1) mandatory monitoring of the absolute neutrophil count (ANC) exclusively during the first 18 weeks of clozapine treatment, 2) that thereafter the prescriber and the well-informed patient decide together about further monitoring frequency, 3) that clozapine treatment must be stopped if the ANC falls below 1.0 × 109/L. Continuation of clozapine or a rechallenge are possible if prescriber and patient determine that the benefits outweigh the risks. 4) National registries which control the haematologic monitoring are unnecessary and do not help to reduce clozapine-induced agranulocytosis. They should at least be restricted to the first 18 weeks of clozapine use.

Exposure to psychotropic medications and COVID-19 course after hospital admission: Results from a prospective cohort study

OBJECTIVE

There is evidence of a bidirectional association between COVID-19 disease and psychiatric disorders. We aimed to assess whether exposure to psychotropic medications prior to hospitalization was associated with mortality or discharge within 30 days after hospital admission.

METHODS

In this prospective study, we included all individuals with a laboratory-confirmed COVID-19 infection who were admitted to the Bologna University Hospital between 1st March 2020 and 31st January 2021. We collected data about pre-existing psychiatric disorders and the use of psychotropic medications at the admission. As univariate analyses, we estimated cumulative incidence functions for 30-day mortality and discharge stratifying by exposure to each of the psychotropic medication classes. Finally, we fitted Cox regression models to estimate cause-specific Hazard Ratios (HR) of 30-day mortality and discharge. Results were adjusted for sociodemographic (age, sex), clinically relevant variables (comorbidity, c-reactive protein levels, severity of disease at presentation, history of smoking, study period), and psychiatric variables (psychiatric disorder diagnosis, number of psychotropic medications).

RESULTS

Out of a total of 1238 hospitalized patients, 316 were prescribed psychotropic medications at the time of admission. Among these, 45 (3.6%) were taking a first-generation antipsychotics (FGA) and 66 (5.3%) a second generation antipsychotic (SGA). Exposure to SGA was associated with increased rates of 30-day mortality (HR = 2.01, 95%CI = 1.02-3.97) and exposure to FGA was associated with decreased rates of 30-day discharge (HR = 0.55, 95%CI = 0.33-0.90).

CONCLUSION

Patients with COVID-19 infection exposed to FGA and SGA may have worse COVID-19 infection outcomes.

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.

Clozapine haematological monitoring for neutropenia: a global perspective

AIMS

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

METHOD

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

RESULTS

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

CONCLUSIONS

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

Clozapine-specific proliferative response of peripheral blood-derived mononuclear cells in Japanese patients with clozapine-induced agranulocytosis

BACKGROUND

Although clozapine-induced granulocytopenia (CIG) is less severe than clozapine-induced agranulocytosis (CIA), and some patients with CIG may not go on to develop serious complications, clozapine is discontinued in cases of both CIA and CIG. Understanding the pathogenic mechanisms of CIA/CIG could provide better management of clozapine therapy. Recently, as a mechanistic insight into adaptive immune systems, European groups reported clozapine-specific proliferative responses and clozapine-specific T cells using blood taken from patients with CIA and/or CIG.

AIMS

The aims of our study are to support this mechanistic evidence and to investigate the difference in the lymphocyte response to clozapine between patients with CIG and those with CIA.

METHODS

Lymphocyte stimulation tests (LSTs) were conducted using CD25-positive cell-depleted peripheral blood-derived mononuclear cells (PBMCs) isolated from blood of four Japanese patients with CIA, four patients with CIG, and nine clozapine-tolerant subjects.

RESULTS

Three of four patients with CIA and one of four patients with CIG showed proliferative responses to clozapine with a stimulation index of greater than 2. In contrast, none of the nine clozapine-tolerant subjects showed any response to clozapine. Olanzapine did not stimulate PBMCs of patients with CIA, patients with CIG, or clozapine-tolerant subjects.

CONCLUSIONS

Clozapine- and CIA-specific lymphocyte reactions in a Japanese population provided supportive evidence that the pathogenesis of CIA is based on adaptive immune reactions. In addition, patients with CIG who show a positive response to an LST may at the very least not be chosen for clozapine-rechallenge and further prospective studies are desirable to verify this hypothesis.

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.

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

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

Clozapine-induced agranulocytosis

Wider use of clozapine, one of the most effective antipshychotic drugs, is precluded by its propensity to cause agranulocytosis. Currently, clozapine is used for treatment-resistant schizophrenia, with mandatory blood count monitoring for the duration of treatment. Agranulocytosis occurs in up to 0.8% of patients and presents a significant medical challenge, despite decreasing mortality rates. In this paper, we review the epidemiology of clozapine-induced agranulocytosis (CLIA), advances in identifying genetic risk factors, and the preventive measures to reduce the risk of CLIA. We discuss the pathogenesis of CLIA, which, despite receiving considerable scientific attention, has not been fully elucidated. Finally, we address the clinical management and suggest the approach to clozapine re-challenge in patients with a previous episode of neutropenia. With a significant proportion of clozapine recipients in Western hemisphere being Black, we comment on the importance of recognizing benign ethnic neutropenia as a potential impediment to clozapine administration. This review aims to aid haematologists and psychiatrists to jointly manage neutropenia and agranulocytosis caused by clozapine.

Initiating clozapine treatment service and characteristics of clozapine-treated patients in a general hospital in Addis Ababa, Ethiopia

Background

At least one-third of patients with schizophrenia suffer from treatment-resistant schizophrenia needing treatment with clozapine. This is the first report on the experience of initiating clozapine service in Ethiopia.

Aim

The aim of this study was to report the experience of setting up clozapine service and describe characteristics of patients treated with clozapine.

Setting

This study was conducted in a general hospital in Addis Ababa, Ethiopia.

Methods

Descriptive summary of the clozapine treatment service and review of characteristics of patients treated with clozapine were conducted. Clinical Global Impression (CGI) Scale and Abnormal Involuntary Movement Scale (AIMS) score were used to measure outcome. Quantitative data were analysed using Statistical Package for the Social Sciences (SPSS) Version 24.

Results

It was possible to provide clozapine treatment in a general hospital using the national guideline. During the first year of initiation of the service, a total of 22 patients were treated. The majority were men (20/22, 90.9%) and in the age group of 30–44 years (11/22, 50%). Indications for clozapine were treatment-resistant schizophrenia (15/22, 68.2%) and tardive dyskinesia (7/22, 31.8%). The average dose of clozapine was 350 mg/day. Common side effects included sedation, constipation and excessive salivation. On CGI Scale, mean severity index score dropped from 5.18 at admission to 3.68 during discharge, and average AIMS score changed from 16.8 to 6.5. None of the patients developed agranulocytosis; however, three patients discontinued because of adverse effects.

Conclusion

Establishing clozapine treatment service was possible in a general hospital in Ethiopia where psychiatric service run by psychiatrists was available. Mechanisms should be in place to ensure adherence to the national guideline.

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.

Safety of a Clozapine Trial Following Quetiapine-Induced Leukopenia: A Case Report

BACKGROUND

The clozapine-derivative quetiapine has been shown in some cases to cause leukopenia and neutropenia.

CASE PRESENTATION

We reported on a case of a young female diagnosed with treatment-resistant schizophrenia. After failed trials of three antipsychotic medications and despite a history of quetiapineinduced leukopenia, clozapine treatment was introduced due to the severity of the patient's symptoms, the limited effective treatment options, and a lack of guidelines on this issue.

RESULT

Over a ten-week period of clozapine treatment at 700 mg per day, the patient developed agranulocytosis. Her white blood cell count sharply dropped to 1.6 × 10⁹ L, and her neutrophils decreased to 0.1 × 10⁹ L. There had been no similar reaction to her previous medications (carbamazepine, risperidone, and haloperidol).

CONCLUSION

The safety of clozapine in a patient who has previously experienced leukopenia and neutropenia with quetiapine requires further investigation. Increased attention should be paid to such cases. Careful monitoring and slow titration are advisable.

Clozapine in the Treatment of Aggression in Conduct Disorder in Children and Adolescents: A Randomized, Double-blind, Controlled Trial

Objective

This study was conducted to compare the efficacy of clozapine vs. risperidone in the treatment of aggression in conduct disorder in children and adolescents.

Methods

Twenty-four children with conduct disorder aged 6 to 16 years were randomized in a prospective, double-blind trial into two groups to receive clozapine or risperidone for 16 weeks. The Modified Overt Aggression Scale score was used as the primary outcome of the study. Secondary outcomes were Child Behavior Checklist (CBCL) externalization (CBCL-E) and internalization factors; Aggression, Hyperactivity and Delinquency subscales of CBCL-E, Child Global Assessment Scale (CGAS), Barnes Akathisia Rating Scale, and Simpson-Angus Scale.

Results

Both antipsychotics were similarly effective in the primary outcome and in most of the secondary ones. Clozapine was more effective in CBCL-E, the delinquency subscale and the CGAS scores than risperidone (p =0.039, 0.010, and 0.021). Two subjects from the clozapine group were excluded due to a low neutrophil count at week four.

Conclusion

Clozapine and risperidone are effective for short-term treatment of aggression in children and adolescents with conduct disorder. Clozapine was more effective than risperidone in conduct externalization factors, delinquency trait and global functioning in children and adolescents. Stronger efficacy of clozapine should be investigated in larger sample sizes using pharmacogenomic studies. White blood cell counts need to be monitored when prescribing clozapine.

Safety of antipsychotics for the treatment of schizophrenia: a focus on the adverse effects of clozapine

Clozapine, a dibenzodiazepine developed in 1961, is a multireceptorial atypical antipsychotic approved for the treatment of resistant schizophrenia. Since its introduction, it has remained the drug of choice in treatment-resistant schizophrenia, despite a wide range of adverse effects, as it is a very effective drug in everyday clinical practice. However, clozapine is not considered as a top-of-the-line treatment because it may often be difficult for some patients to tolerate as some adverse effects can be particularly bothersome (i.e. sedation, weight gain, sialorrhea etc.) and it has some other potentially dangerous and life-threatening side effects (i.e. myocarditis, seizures, agranulocytosis or granulocytopenia, gastrointestinal hypomotility etc.). As poor treatment adherence in patients with resistant schizophrenia may increase the risk of a psychotic relapse, which may further lead to impaired social and cognitive functioning, psychiatric hospitalizations and increased treatment costs, clozapine adverse effects are a common reason for discontinuing this medication. Therefore, every effort should be made to monitor and minimize these adverse effects in order to improve their early detection and management. The aim of this paper is to briefly summarize and provide an update on major clozapine adverse effects, especially focusing on those that are severe and potentially life threatening, even if most of the latter are relatively uncommon.

Olanzapine-induced and Risperidone-induced Leukopenia: A Case of Synergistic Adverse Reaction?

Leukopenia is a known hematological side effect of atypical antipsychotics. We report a case of an antipsychotic-naive patient with schizophrenia who developed leukopenia after a single dose of olanzapine, which worsened during subsequent treatment with risperidone. Normalization of the white blood cell counts occurred within 24 hours of risperidone discontinuation. Possible synergistic mechanisms underlying olanzapine-induced and risperidone-induced leukopenia are discussed. This case highlights the challenges in identifying and managing nonclozapine antipsychotic-induced leukopenia in a susceptible patient.

Human neutrophils show decreased survival upon long-term exposure to clozapine

OBJECTIVE

Clozapine is an atypical antipsychotic prescribed for treatment-resistant schizophrenic patients, but treatment with clozapine is strictly limited because it can induce lethal-hematologic side effects. We investigated the effects of short- and long-term exposure of human neutrophils derived from healthy subjects to clozapine and compared them with the effects of reactive metabolite of clozapine, olanzapine, and doxorubicin.

METHODS

Neutrophils were exposed to clozapine and olanzapine (1, 10, 50, or 100 μM), reactive metabolite of clozapine (50 or 100 μM), or doxorubicin (0.2 μM) and cultured for a short (2 hr) or long (24 or 48 hr) duration, and then the survival rate of neutrophils was calculated.

RESULTS

Decreased human neutrophil survival was observed in short-term exposure to clozapine (100 μM) and long-term exposure to clozapine even at a lower concentration (50 μM). A similar phenomenon was observed in reactive metabolite of clozapine and long-term exposure to doxorubicin (0.2 μM), but not to olanzapine (1-100 μM).

CONCLUSIONS

The effect of long-term exposure to clozapine on neutrophil survival is plausibly associated with delayed onset of agranulocytosis after initial exposure. Our results suggest that human neutrophils are vulnerable to clozapine and its reactive metabolite in a concentration- and time-dependent manner.

Role of cytokine changes in clozapine-induced fever: A cohort prospective study

AIM

Clozapine-associated fever is common but the specific cytokine changes and treatment durations that may cause fever remain unknown. We investigated the association between inflammatory cytokine changes and clozapine-induced fever in patients who were treated with clozapine.

METHODS

Forty-three patients with schizophrenia or schizoaffective disorder, diagnosed by using the Chinese Version of the Mini International Neuropsychiatric Interview, were treated with clozapine for the first time (first-time use group, n = 22) or for more than 6 months (long-term use group, n = 21). The Positive and Negative Syndrome Scale, tympanic temperature, and levels of tumor necrosis factor-α (TNF-α), interferon-γ (INF-γ), interleukin-2 (IL-2), and interleukin-6 (IL-6) were determined at baseline and weeks 1, 2, 3, 4, and 6. A multiple linear regression with generalized estimating equation methods was used to analyze the association between the changes in the cytokine levels and clozapine-induced fever in the different groups.

RESULTS

The IL-6 level changes were significantly different between the two groups (P = 0.04). In the first-time use group, the fever rate was increased (47.1%) compared with the long-term use group (5.6%, P = 0.005). Moreover, in these patients, the TNF-α, INF-γ, IL-2, and IL-6 levels were significantly (P < 0.001) different from patients who did not develop a fever. An interaction effect with the different treatment duration groups and fever development was only significant for IL-6 (P < 0.001).

CONCLUSION

Patients who were treated with clozapine for the first time have an increased rate of developing a fever, and IL-6 might have a specific role in the interaction effect between treatment duration and fever development.

Medical Complications of Psychiatric Treatment: An Update

Psychiatric medications are used commonly in hospitalized patients and are particularly indicated in patients who are critically ill to manage many conditions. Due to their many indications in the intensive care unit (ICU), psychiatric medications should be closely monitored in these medically compromised patients for adverse reactions and medical complications because they may affect essentially all organ systems. These range from life-threatening reactions to other less significant effects, such as sedation, to other detrimental complications, such as pancreatitis. Knowledge of psychopharmacology as well as the diagnosis and treatment of these complications is imperative in treating patients in the ICU.

Potential Mechanisms of Hematological Adverse Drug Reactions in Patients Receiving Clozapine in Combination With Proton Pump Inhibitors

Clozapine is a second-generation antipsychotic which has proven efficacy in treating the symptoms of schizophrenia. Although clozapine therapy is associated with a number of adverse drug reactions, it is frequently used. One of the most common adverse drug reactions is gastroesophageal reflux disease which is an indication for treatment with proton pump inhibitors (PPIs). Coadministration of clozapine and PPIs increases the risk of hematological adverse drug reactions, including neutropenia and agranulocytosis. The mechanism in idiosyncratic agranulocytosis is not dose related and involves either a direct toxic or an immune-allergic effect. It is suspected that the clozapine metabolites nitrenium ion and N-desmethylclozapine may cause apoptosis or impair growth of granulocytes. Formation of N-desmethylclozapine is correlated with activity of the cytochrome P450 enzymes 1A2 and 3A4 (CYP1A2 and CYP3A4). Nitrenium ion is produced by the flavin-containing monooxygenase system of leukocytes. A drug interaction between clozapine and a PPI is a consequence of the induction of common metabolic pathways either by the PPI or clozapine. Findings to date suggest that indirect induction of flavin-containing monooxygenase by omeprazole through the aryl hydrocarbon receptor increases the expression of the enzyme mRNA and in the long term may cause the increase in activity. Moreover, induction of CYP1A2, especially by omeprazole and lansoprazole, may increase the serum concentration of N-desmethylclozapine, which can accumulate in lymphocytes and may achieve toxic levels. Another hypothesis that may explain hematological adverse drug reactions is competitive inhibition of CYP2C19, which may contribute to increased serum concentrations of toxic metabolites.

Risperidone-induced reversible neutropenia

This case report presents a 44-year-old man with a history of schizophrenia who developed neutropenia on risperidone therapy. The patient's laboratory reports showed a gradual decline of leukocytes and neutrophils after resolution and rechallenging. This was reversed with the discontinuation of risperidone and by switching to olanzapine. In this case report, we also discuss the updated evidence base for management of risperidone-induced neutropenia.

Pharmacogenomic Study of Clozapine-Induced Agranulocytosis/Granulocytopenia in a Japanese Population

BACKGROUND

Clozapine-induced agranulocytosis (CIA)/clozapine-induced granulocytopenia (CIG) (CIAG) is a life-threatening event for schizophrenic subjects treated with clozapine.

METHODS

To examine the genetic factor for CIAG, a genome-wide pharmacogenomic analysis was conducted using 50 subjects with CIAG and 2905 control subjects.

RESULTS

We identified a significant association in the human leukocyte antigen (HLA) region (rs1800625, p = 3.46 × 10(-9), odds ratio [OR] = 3.8); therefore, subsequent HLA typing was performed. We detected a significant association of HLA-B*59:01 with CIAG (p = 3.81 × 10(-8), OR = 10.7) and confirmed this association by comparing with an independent clozapine-tolerant control group (n = 380, p = 2.97 × 10(-5), OR = 6.3). As we observed that the OR of CIA (OR: 9.3~15.8) was approximately double that in CIG (OR: 4.4~7.4), we hypothesized that the CIG subjects were a mixed population of those who potentially would develop CIA and those who would not develop CIA (non-CIA). This hypothesis allowed the proportion of the CIG who were non-CIA to be calculated, enabling us to estimate the positive predictive value of the nonrisk allele on non-CIA in CIG subjects. Assuming this model, we estimated that 1) ~50% of CIG subjects would be non-CIA; and 2) ~60% of the CIG subjects without the risk allele would be non-CIA and therefore not expected to develop CIA.

CONCLUSIONS

Our results suggest that HLA-B*59:01 is a risk factor for CIAG in the Japanese population. Furthermore, if our model is true, the results suggest that rechallenging certain CIG subjects with clozapine may not be always contraindicated.

Relation of the Allelic Variants of Multidrug Resistance Gene to Agranulocytosis Associated With Clozapine

Clozapine use is associated with leukopenia and more rarely agranulocytosis, which may be lethal. The drug and its metabolites are proposed to interact with the multidrug resistance transporter (ABCB1/MDR1) gene product, P-glycoprotein (P-gp). Among various P-glycoprotein genetic polymorphisms, nucleotide changes in exons 26 (C3435T), 21 (G2677T), and 12 (C1236T) have been implicated for changes in pharmacokinetics and pharmacodynamics of many substrate drugs. In this study, we aimed to investigate the association between these specific ABCB1 polymorphisms and clozapine-associated agranulocytosis (CAA). Ten patients with a history of CAA and 91 control patients without a history of CAA, despite 10 years of continuous clozapine use, were included. Patient recruitment and blood sample collection were conducted at the Hacettepe University Faculty of Medicine, Department of Psychiatry, in collaboration with the members of the Schizophrenia and Other Psychotic Disorders Section of the Psychiatric Association of Turkey, working in various psychiatry clinics. After DNA extraction from peripheral blood lymphocytes, genotyping was performed using polymerase chain reaction and endonuclease digestion. Patients with CAA had shorter duration of clozapine use but did not show any significant difference in other clinical, sociodemographic characteristics and in genotypic or allelic distributions of ABCB1 variants and haplotypes compared with control patients. Among the 10 patients with CAA, none carried the ABCB1 all-variant haplotype (TT-TT-TT), whereas the frequency of this haplotype was approximately 12% among the controls. Larger sample size studies and thorough genetic analyses may reveal both genetic risk and protective factors for this serious adverse event.

[Clozapine rechallenge after neutropenia in resistant schizophrenia: A review]

INTRODUCTION

Clozapine is an atypical antipsychotic known for its efficacy in refractory schizophrenia. One of the adverse effects is neutropenia. This dysplasia is a rare but major side effect which leads to a discontinuation and constitutes further contraindication. Thereafter, therapeutic options decrease dramatically. Mechanisms involved are not well known at this time and can be combined. A toxic hypothesis may be more likely than an immune-allergic one.

METHODS

We have reviewed publications on Medline describing procedures that allowed clozapine rechallenge after blood dyscrasia in refractory schizophrenia. Three different procedures were found: simple rechallenge, rechallenge with lithium and rechallenge with Granulocyte - colony stimulating factor (G-CSF). Rechallenge could be simple or multiple.

RESULTS

These past years, clozapine have been rechallenged successfully after neutropenia thanks to different procedures, the different options being simple rechallenge, rechallenge with lithium and/or rechallenge with G-CSF. Lithium as G-CSF are used to increase neutrophil blood rate and prevent neutropenia recurrence after clozapine rechallenge. G-CSF was first used within the context of chemotherapy and extends now to clozapine-induced neutropenia. Both for lithium and G-CSF, numerous procedures are reviewed and cannot be compared.

DISCUSSION

Publications are limited but increasing, and they point out that a careful rechallenge can be successful. However, interesting data can be extracted. First, clozapine is more likely to be incriminated in neutropenia when patients receive many drugs, but a careful study could prevent some discontinuation. Indeed, other drugs or a hematologic disease could be involved. Moreover, several contributing factors have been found such as HLA group and drug interaction. Ethnic origin also affects neutrophil rate. That is why, in Great Britain, a subgroup of patients "benign ethnic neutropenia" has been introduced to enlarge threshold and allow these patients to access clozapine despite lower blood counts. Then, rechallenge choice has to be done on a case-by-case basis and only after considering the benefits and risks of such a treatment. Most of the time, clinical advice of rechallenge arises from the inefficiency of other antipsychotics and even sismotherapy failure. Patients and sometimes families have to be informed and give their consent. Preventive measures have been found such as taking a hematologic recommendation and doing twice-a-week blood sample monitoring. With regards lithium and G-CSF, some efficient doses are assumed (lithium: 0,4-1,1 mEq/L and G-CSF>0,3 mg/week). Lithium as G-CSF may have other adverse effects which need to be considered. There is no successful rechallenge reported after agranulocytosis. Some publications highlight that if neutropenia occurs on rechallenge, it will do so more quickly and more severe than at the time of initial trial of clozapine.

CONCLUSION

There is emerging evidence of successful clozapine rechallenging. However, further investigations are required as randomized controlled trials to reassess guidelines and establish the safety and effectiveness of the different procedures. Because of the practical and ethical difficulties of designing such studies, referral hospitals could be elected, and common background writing proposed in order to ease data comparison.

Olanzapine-Induced Neutropenia

Olanzapine-induced neutropenia is a rare adverse effect that is currently poorly described in literature. Although neutropenia is a known adverse effect of clozapine, it has been associated with the use of other antipsychotic medications like olanzapine. This case report describes and reviews a case of olanzapine-induced neutropenia in a schizophrenic patient. Although the mechanism of antipsychotic-induced neutropenia is still debated, this report attempts to discuss current theories as well as supply evidence in literature of this rare but potentially dangerous adverse effect.

The atypical antipsychotic clozapine selectively inhibits interleukin 8 (IL-8)-induced neutrophil chemotaxis

Clozapine is the most effective antipsychotic to date, but its benefits are counterbalanced by the risk of severe hematological effects. In this study, we analyzed whether clozapine inhibits polymorphonuclear (PMN) leukocyte chemotaxis. We found that clozapine, within the therapeutic concentration range, potently and selectively inhibits PMN chemotaxis induced by interleukin 8 (IL-8), a chemokine inducing neutrophil migration. The effect was not due to its action at dopamine, serotonin and muscarinic receptors, or to a direct antagonism to IL-8 receptors. Furthermore, clozapine did not inhibit PMN chemotaxis by its presumed toxic mechanism. In fact, after an overnight incubation in cell culture, the drug did not increase the physiological PMN apoptosis. An interference of clozapine with the autocrine release of leukotriene B4 (LTB4), a secondary chemoattractant secreted by neutrophils in response to the primary chemoattractant IL-8, was hypothesized. In agreement with this hypothesis, clozapine attenuated the IL-8-induced release of LTB4 in PMNs. A series of experiments with an antagonist of the LTB4 receptor, U75302, and an inhibitor of LTB4 synthesis, zileuton, provided support to this conjecture. Intriguingly MK-571, an inhibitor of the multi-drug resistance protein MRP4, playing a pivotal role in effluxing LTB4, completely blocked PMN chemotaxis induced by IL-8, but gave conflicting results when tested for its ability to reduce LTB4 release, increasing LTB4 efflux by itself but reducing the release when in combination with IL-8. The reduction of PMN chemotaxis due to clozapine could predispose patients to infections. Whether this effect is a prelude to clozapine agranulocytosis requires further investigation.

Nonchemotherapy drug-induced neutropenia and agranulocytosis: could medications be the culprit?

Drug-induced agranulocytosis is a severe complication that has been implicated with most classes of medications. Medications such as clozapine, trimethoprim-sulfamethoxazole and methimazole have been more commonly associated with agranulocytosis than other agents. Although the pathogenesis isn't fully elucidated, it appears to be two-fold with a direct toxicity to the myeloid cell line and immune-mediated destruction. Patients may be asymptomatic at the time neutropenia is discovered or may present with more severe complications such as sepsis. In approximately 5% of cases drug-induced agranulocytosis may be fatal. Management of drug-induced agranulocytosis includes the immediate discontinuation of the offending medication, initiation of broad-spectrum antibiotics and consideration of the use of granulocyte colony-stimulating factors in high-risk patients.

Antipsychotic drug-associated gene-miRNA interaction in T-lymphocytes

Antipsychotic drugs (APDs) can have a profound effect on the human body that extends well beyond our understanding of their neuropsychopharmacology. Some of these effects manifest themselves in peripheral blood lymphocytes, and in some cases, particularly in clozapine treatment, result in serious complications. To better understand the molecular biology of APD action in lymphocytes, we investigated the influence of chlorpromazine, haloperidol and clozapine in vitro, by microarray-based gene and microRNA (miRNA) expression analysis. JM-Jurkat T-lymphocytes were cultured in the presence of the APDs or vehicle alone over 2 wk to model the early effects of APDs on expression. Interestingly both haloperidol and clozapine appear to regulate the expression of a large number of genes. Functional analysis of APD-associated differential expression revealed changes in genes related to oxidative stress, metabolic disease and surprisingly also implicated pathways and biological processes associated with neurological disease consistent with current understanding of the activity of APDs. We also identified miRNA-mRNA interaction associated with metabolic pathways and cell death/survival, all which could have relevance to known side effects of APDs. These results indicate that APDs have a significant effect on expression in peripheral tissue that relate to both known mechanisms as well as poorly characterized side effects.

Efficacy and safety of pharmacotherapy in cancer-related psychiatric disorders across the trajectory of cancer care: a review

At least 25-30% of patients with cancer and an even higher percentage of patients in an advanced phase of illness meet the criteria for a psychiatric diagnosis, including depression, anxiety, stress-related syndromes, adjustment disorders, sleep disorders and delirium. A number of studies have accumulated over the last 35 years on the use of psychotropic drugs as a pillar in the treatment of psychiatric disorders. Major advances in psycho-oncology research have also shown the efficacy of psychotropic drugs as adjuvant treatment of cancer-related symptoms, such as pain, hot flushes, pruritus, nausea and vomiting, fatigue, and cognitive impairment. The knowledge about pharmacokinetics and pharmacodynamics, clinical use, safety, side effects and efficacy of psychotropic drugs in cancer care is essential for an integrated and multidimensional approach to patients treated in different settings, including community-based centres, oncology, and palliative care. A search of the major databases (MEDLINE, Embase, PsycLIT, PsycINFO, the Cochrane Library) was conducted in order to summarize relevant data concerning the efficacy and safety of pharmacotherapy for cancer-related psychiatric disorders in cancer patients across the trajectory of the disease.

Pharmacogenetics of antipsychotics

OBJECTIVE

During the past decades, increasing efforts have been invested in studies to unravel the influence of genetic factors on antipsychotic (AP) dosage, treatment response, and occurrence of adverse effects. These studies aimed to improve clinical care by predicting outcome of treatment with APs and thus allowing for individualized treatment strategies. We highlight most important findings obtained through both candidate gene and genome-wide association studies, including pharmacokinetic and pharmacodynamic factors.

METHODS

We reviewed studies on pharmacogenetics of AP response and adverse effects published on PubMed until early 2012. Owing to the high number of published studies, we focused our review on findings that have been replicated in independent studies or are supported by meta-analyses.

RESULTS

Most robust findings were reported for associations between polymorphisms of the cytochrome P450 system, the dopamine and the serotonin transmitter systems, and dosage, treatment response, and adverse effects, such as AP-induced weight gain or tardive dyskinesia. These associations were either detected for specific medications or for classes of APs.

CONCLUSION

First promising and robust results show that pharmacogenetics bear promise for a widespread use in future clinical practice. This will likely be achieved by developing algorithms that will include many genetic variants. However, further investigation is warranted to replicate and validate previous findings, as well as to identify new genetic variants involved in AP response and for replication of existing findings.

Seasonal changes in gene expression represent cell-type composition in whole blood

Seasonal patterns in behavior and biological parameters are widespread. Here, we examined seasonal changes in whole blood gene expression profiles of 233 healthy subjects. Using weighted gene co-expression network analysis, we identified three co-expression modules showing circannual patterns. Enrichment analysis suggested that this signal stems primarily from red blood cells and blood platelets. Indeed, a large clinical database with 51 142 observations of blood cell counts over 3 years confirmed a corresponding seasonal pattern of counts of red blood cells, reticulocytes and platelets. We found no direct evidence that these changes are linked to genes known to be key players in regulating immune function or circadian rhythm. It is likely, however, that these seasonal changes in cell counts and gene expression profiles in whole blood represent biological and clinical relevant phenomena. Moreover, our findings highlight possible confounding factors relevant to the study of gene expression profiles in subjects collected at geographical locations with disparaging seasonality patterns.

Assessment of possible immunotoxicity of the antipsychotic drug clozapine

OBJECTIVES

The immunomodulatory effects of clozapine (CLZ), antipsychotic drug, were investigated in vivo using female Balb/c mice. The main aim of this study was to evaluate the immunomodulatory effects of CLZ, antipsychotic drug, following daily intraperitoneal injection to female Balb/c mice over a period of 21 days.

METHODS

Mice were divided into five groups, eight animals per group. Group I, served as a control group, received only the vehicle. Groups II-V received a daily intraperitoneal dose of CLZ (1, 5, 10 and 20 mg/kg, respectively) over a period of 21 days.

KEY FINDINGS

CLZ has shown a significant decrease in the animal body weight, and it showed a significant decrease in the percentage of circulating neutrophils and lymphocytes while circulating monocytes were increased. The immunotoxicity has been also assessed by evaluating spleen cellularity, humoral immune response to a foreign antigen using sheep red blood cells and delayed-type hypersensitivity reaction. The results showed a marked suppression in these responses in CLZ-treated mice compared with the control group. Detectable changes have also been noticed in the histology of the footpad tissue and spleen.

CONCLUSIONS

Results showed significant immunomodulatory effects of CLZ when used in Balb/c mice.

A case with neutropenia related with the use of various atypical antipsychotics

Herein, we report here a case of a 21-year-old patient with a conduct disorder, who had neutropenia associated with treatment with 4 different antipsychotics (olanzapine, quetiapine, risperidone, and aripiprazole) on a sequential basis. This case supports the hypothesis that patients who developed antipsychotic-induced neutropenia on one medication are more likely to develop neutropenia when taking other antipsychotics. Based on this finding, we may suggest that the number of white blood cell and neutrophil counts in patients with a history of antipsychotic-induced neutropenia needs to be carefully monitored during antipsychotic treatment.

Psychopharmacology in psycho-oncology

Psychopharmacological intervention is a major clinical and research area in oncology and palliative care. Over the last 35 years, psychotropic drugs have been shown to have a number of important indications for the treatment of the most common psychiatric disorders, such as depression, anxiety, stress-related syndromes, severe adjustment disorders, sleep disorders and delirium, which combined affect at least 30-40% of patients with cancer and even a higher percentage of patients in an advanced phase of illness. The availability of new drugs, with less side-effects and safer pharmacological profiles, has been a major advance in clinical psycho-oncology. Interestingly, several drugs have also been found to be helpful for the adjuvant treatment of cancer-related symptoms, such as pain, hot flashes, pruritus, nausea and vomiting, fatigue, and cognitive impairment, making psychopharmacology an important tool for the improvement of cancer patients' quality of life. The aim of this paper is to summarize recent relevant data concerning the use of psychotropic drugs, namely antidepressants, anxiolytics, antipsychotics, anticonvulsants and psychostimulants in patients with cancer.

Plasma clozapine and norclozapine in relation to prescribed dose and other factors in patients aged <18 years: data from a therapeutic drug monitoring service, 1994-2010

AIM

Clozapine is used in children and adolescents to treat early onset schizophrenia, but data on efficacy and on the plasma clozapine concentrations attained are limited.

METHODS

We studied data from a clozapine therapeutic drug monitoring (TDM) service, patients in the UK and Eire aged <18 years, 1994-2010. Multiple linear regression analysis was performed to investigate the relationship between plasma clozapine concentration and dose, age, sex, body weight, plasma clozapine:norclozapine ratio (clozapine metabolic ratio (MR)) and smoking habit.

RESULTS

There were 1408 samples from 454 patients, 267 (59%) males aged at time of first sample (median = 17; range = 8-17 years) and 187 (41%) females aged 16 (10-17) years. The plasma clozapine concentration was <0.35 mg L(-1) in 36%, and ≥0.60 mg L(-1) in 31% of samples (6.4% samples ≥1.0 mg L(-1) ). Although plasma clozapine was broadly related to prescribed dose, there was much variation: 10% of samples had plasma clozapine >0.60 mg L(-1) at prescribed clozapine doses of 50-150 mg d(-1) (66% <0.35 mg L(-1) ), while 12% of samples had plasma clozapine <0.35 mg L(-1) at doses ≥650 mg d(-1) (62% >0.6 mg L(-1) ). The covariates studied in the 16-17-year-olds had proportionately similar influences to those observed in adults. Together they explained 48% of the variance observed in plasma clozapine, with dose, smoking habit, MR and sex being major influences. In the younger patients, there were very few smokers, and the influence of sex did not reach statistical significance.

CONCLUSIONS

As in adults, clozapine TDM may help in assessing adherence and in dose adjustment, for example if smoking habit changes.

Molecular and cellular analysis of human histamine receptor subtypes

The human histamine receptors hH(1)R and hH(2)R constitute important drug targets, and hH(3)R and hH(4)R have substantial potential in this area. Considering the species-specificity of pharmacology of H(x)R orthologs, it is important to analyze hH(x)Rs. Here, we summarize current knowledge of hH(x)Rs endogenously expressed in human cells and hH(x)Rs recombinantly expressed in mammalian and insect cells. We present the advantages and disadvantages of the various systems. We also discuss problems associated with the use of hH(x)R antibodies, an issue of general relevance for G-protein-coupled receptors (GPCRs). There is much greater overlap in activity of 'selective' ligands for other hH(x)Rs than the cognate receptor subtype than generally appreciated. Studies with native and recombinant systems support the concept of ligand-specific receptor conformations, encompassing agonists and antagonists. It is emerging that for characterization of hH(x)R ligands, one cannot rely on a single test system and a single parameter. Rather, multiple systems and parameters have to be studied. Although such studies are time-consuming and expensive, ultimately, they will increase drug safety and efficacy.

Real-world effectiveness of clozapine in patients with bipolar disorder: results from a 2-year mirror-image study

OBJECTIVES

Clozapine remains the drug of choice for treatment-resistant schizophrenia but the evidence for its use in severe bipolar disorder (BD) remains sparse.

METHODS

A pharmaco-epidemiologic database study was carried out in Denmark, investigating the effectiveness of clozapine in BD patients (without a schizophrenia-spectrum disorder), between 1996 and 2007, using a two-year mirror-image design.

RESULTS

A total of 21473 patients with a lifetime diagnosis of International Classification of Diseases-10 (ICD-10) BD were identified, of which only 326 (1.5%) were treated with clozapine and were included in the mirror-image analysis. The mean follow-up time was 544 ± 280 days, the mean clozapine dose was 307.4 mg [95% confidence interval (CI): 287.9-328.2], and 39.3% were male. During clozapine treatment, the mean number of bed-days decreased from 177.8 (95% CI: 149.4-211.6) to 34.6 (95% CI: 24.8-48.2) (p < 0.001). The mean number of admissions was reduced from 3.2 (95% CI: 2.9-3.7) to 2.0 (95% CI: 1.6-2.4) (p < 0.001). Overall, 240 patients (73.6%) had reduced bed-days and 130 (39.9%) were not admitted while treated with clozapine. Moreover, the number of psychotropic co-medications was reduced from 4.5 defined daily doses (DDD) (25-75 percentiles: 2.4-8.2) to 3.9 DDD (25-75 percentiles: 2.4-6.1) (p = 0.045). Somatic hospital visits for intentional self-harm/overdose reduced significantly from 8.3% to 3.1% (p = 0.004). However, non-psychotropic co-medication use for medical conditions did not increase; 0.7 DDD (25-75 percentiles: 0.0-2.9) to 0.8 DDD (25-75 percentiles: 0.1-2.89) (p = 0.3).

CONCLUSIONS

Clozapine use for BD was associated with a significant and clinically relevant reduction in the number of bed-days, psychiatric admissions, psychotropic co-medications, and hospital contact for self-harm/overdose, without increased medical treatments. Clozapine seems to be an appropriate choice for treatment-resistant BD and should be investigated in randomized controlled trials.

Geographical and temporal variations in clozapine prescription for schizophrenia

Despite its unsurpassed efficacy in treatment-resistant schizophrenia, clozapine remains underutilized. Trends in the prescription of clozapine in patients with ICD-10 F20.x schizophrenia were assessed using data from Danish national registers. Three substudies were carried out: (i) an assessment of differences in national prescription patterns between 1996 and 2007 using a cross-sectional design; (ii) a comparison of time from first schizophrenia diagnosis to first prescription of clozapine in a five-year cohort study, using the Cox regression model, of two patient groups who were first diagnosed in 1996 and in 2003; (iii) an assessment of differences in the general psychiatric hospitals' use of clozapine in 2009. The results are as follows: (i) The percentage of schizophrenia patients receiving clozapine rose from 9.0% in 1996 to 10.1% in 2007 (p<0.001). In the same period, the percentage of patients having clozapine treatment augmented with another antipsychotic increased from 43.1% to 64.2%, p<0.001. (ii) Time from diagnosis with schizophrenia until first clozapine prescription was longer for patients diagnosed in 2003 compared to those diagnosed in 1996 (HR: 0.28 CI: 0.16-0.49). (iii) In 2009 there was significant variation in clozapine administration from one hospital to the other, with percentages of patients receiving the drug ranging from 5.7% to 16.8%, with 10.2% as the national mean. Although, the percentage of schizophrenia patients receiving clozapine increased from 1996 to 2007, the time from diagnosis of schizophrenia until first prescription of clozapine increased.

Hematological clozapine monitoring with a point-of-care device: a randomized cross-over trial

Clozapine remains the drug of choice for patients with treatment-resistant schizophrenia, who show a response rate of about 50% despite their unresponsiveness to other antipsychotics. Although treatment with clozapine can lead to considerable savings on bed days, the drug is underutilized for several reasons, perhaps most importantly because of the mandatory hematological monitoring. The Chempaq Express Blood Counter (Chempaq XBC) is a point-of-care device providing counts of white blood cells (WBC) and granulocytes based on a capillary blood sampling. A randomized cross-over trial design was used comparing capillary blood sampling using a point-of-care device with traditional venous blood sampling. Patients were randomized to two sequences starting with either capillary or venous blood sampling followed by a repeated sequence. Primary outcome was measured on a 10-cm visual analog scale. Eighty-five patients were included in the test. Eight (9.4%) dropped out before completion. Patients indicated that they found capillary blood monitoring less painful than venous sampling (VAS ratings: 0.55 cm 25-75 percentiles: 0.1-1.4 cm vs. 1.75 cm 25-75 percentiles: 0.7-2.6, p<0.001). They also felt less inconvenienced by the point-of-care method than the traditional blood sampling, which involved traveling to the laboratory clinical (0.3 cm 25-75 percentiles: 0.05-0.7 vs. 2.3 cm 25-75 percentiles: 0.75-4.5, p<0.001). For hematological monitoring of clozapine patients a point-of-care device based on capillary blood sampling is better tolerated than traditional venous blood sampling.