Restarting clozapine after neutropenia: evaluating the possibilities and practicalities

Decoding Clozapine-Induced Agranulocytosis: Unraveling Interactions and Mitigation Strategies

Agranulocytosis represents a severe complication associated with the administration of clozapine. Clozapine is an antipsychotic medication that has demonstrated substantial efficacy in remediating refractory schizophrenia and various other psychiatric disorders. Nonetheless, it is crucial to monitor patients for neutropenia regularly during clozapine therapy. Therefore, this article aimed to delve into the prevalence of agranulocytosis during clozapine treatment by scrutinizing the extant literature to discern trends and correlations. This review endeavored to explore factors such as drug interactions, dose-related factors, duration of treatment, and genetic predispositions that could potentially influence the likelihood of patients developing agranulocytosis while undergoing clozapine therapy. Moreover, this review enunciates the ramifications of agranulocytosis on both patients and healthcare providers and meticulously evaluates the strategies to mitigate this risk and ensure optimal patient outcomes.

Risks and benefits of clozapine and lithium co-prescribing: A systematic review and expert recommendations

OBJECTIVES

To identify the risks and benefits of clozapine‑lithium co-prescription.

METHODS

Articles published in English or French were identified with a MEDLINE, Web of Sciences and PsycINFO search, from inception through January 2023, using the term 'clozapine' in combination with 'lithium'. Data were synthesized narratively.

RESULTS

Of the 67 articles included in the review, more than half (n = 38, 56.7 %) were focused on clozapine-related blood dyscrasia. A body of evidence drawn from case reports and retrospective chart studies highlights the potential benefits of lithium prescription for clozapine-related neutropenia, since this strategy may avoid clozapine discontinuation or allow its rechallenge. The most documented adverse drug reactions (ADRs) associated with clozapine‑lithium co-prescription are neurotoxic events, which may be prevented or detected early by clinical, electroencephalographic and therapeutic drug monitoring. Causality assessment cannot be established for other reported ADRs occurring during clozapine‑lithium co-prescription. The benefits of the combined prescription on psychotic and/or mood symptoms are poorly documented.

CONCLUSION

The risks and benefits of clozapine‑lithium co-prescription require further exploration as the combination might significantly contribute to reducing underprescription or premature discontinuation of clozapine.

Can lithium be used in the setting of clozapine commencement in patients with COVID-19 associated neutropenia: A case report

COVID-19 infection may increase the likelihood of neutropenia in patients already on clozapine. In clozapine treated patients experiencing COVID-19 associated neutropenia, adjunct therapy with lithium can be considered.

[Safety aspects during treatment with clozapine. : Monitoring and rechallenge - a narrative review]

BACKGROUND

Due to its unique efficacy in treatment-resistant schizophrenia, discontinuation of treatment with clozapine is frequently associated with a significant worsening of symptoms, but also with an increased risk of suicide. Based on the literature, this review aims at summarizing different monitoring recommendations in order to be able to continue this therapy despite the occurrence of side effects. In addition, we provide recommendations when rechallenge of a previously stopped treatment with clozapine can be considered and when a definite discontinuation must take place.

MATERIAL AND METHODS

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

RESULTS

If agranulocytosis or cardiomyopathy develops, treatment with clozapine must be discontinued and should not be resumed thereafter. In contrast, treatment with clozapine which had to be discontinued due to myocarditis or prolongation of the QTc interval may be continued if left ventricular function is normal or after normalization of the QTc interval. Other side effects are usually not absolute contraindications for rechallenge but often require the adjunctive use of additional pharmacologic and non-pharmacologic measures.

CONCLUSION

Taking into consideration various monitoring recommendations, cessation of treatment with clozapine can often be prevented or treatment with clozapine that has been discontinued due to side effects can be resumed.

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.

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

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

Combination of strategies to initiate clozapine for refractory schizophrenia in a patient with low neutrophil levels

Clozapine is the only drug with confirmed efficacy for refractory schizophrenia; however, its use is restricted due to the risk of potentially life-threatening side effects, such as agranulocytosis. Although this restriction ensures safety against haematological risks, some patients with refractory schizophrenia who have low neutrophil levels may miss the opportunity to receive clozapine treatment. We herein report the case of a patient with refractory schizophrenia and low neutrophil levels who was successfully initiated on clozapine treatment after the use of several methods for increasing neutrophil levels. These strategies consisted of discontinuation of antipsychotics, treatment with lithium carbonate and adenine, and light exercise before blood testing. Combining these procedures may be an effective option in the treatment of patients with refractory schizophrenia whose neutrophil levels are not sufficient to initiate clozapine.

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.

Clozapine Response in Schizophrenia and Hematological Changes

BACKGROUND

Clozapine is the only effective medication for treatment-resistant schizophrenia; however, its mechanism of action remains unclear. The present study explored whether its effectiveness is related to changes in hematological measures after clozapine initiation.

METHODS

Patients with treatment-resistant schizophrenia commenced on clozapine between January 2007 and December 2014 by the United Kingdom's largest mental health trust were identified from electronic patient records. Hematological data from these patients were obtained from a monitoring registry. White blood cell, neutrophil, and platelet count were assessed at baseline and during the early phase of clozapine treatment. Clozapine response at 3 months was defined as "much," or "very much" improved on the seven-point Clinical Global Impression-Improvement (CGI-I) subscale.

RESULTS

In the total sample (n = 188), clozapine initiation was associated with a significant transient increase (peaking in weeks 3 to 4) in white blood cell, neutrophil, and platelet count (P < 0.001). There were 112 (59.6%) patients that responded to treatment; however, none of the hematological factors assessed at baseline, nor changes in these factors, were directly associated with treatment response.

IMPLICATIONS

Clozapine treatment is associated with transient hematological changes during the first month of treatment; however, there was no evidence that these were related to the therapeutic response.

Never Say Never: Successful Clozapine Rechallenge After Multiple Episodes of Neutropenia

Clozapine is a second-generation antipsychotic with a superior efficacy for the management of treatment-resistant schizophrenia but underutilized because of potential side effects. A 59-year-old Caucasian male veteran was transferred from the long-term care unit to the acute psychiatry unit because of suicidality. He was noted as having a long-standing history of psychosis with significant referential and paranoid delusions. He had experienced two previous trials of clozapine; although he had significant response in the past, both trials ended in neutropenia and an absolute neutrophil count <500 cells per microliter, despite the second trial also including supplemental "as-needed" doses of pegfilgrastim to manage decline in neutrophil counts. This particular strategy of filgrastim use was determined to be a weakness of the second trial. A PubMed search identified recent literature that discussed preemptive dosing of filgrastim to prevent neutropenia. Thus, a protocol was established to administer 300 μg filgrastim subcutaneously, three times weekly, concurrently with clozapine initiation. This plan was discussed on local and national levels to achieve consensus before its initiation. Using a revised, patient-specific protocol led to successful initiation of clozapine and the ability to maintain the regimen for over 24 months without interruption or any further suicidal ideation.

Clinical Utility and Safety of Slower-than-Recommended Titration of Clozapine for Treatment-Resistant Schizophrenia: a Retrospective Cohort Study

Slow titration of clozapine is recommended given the risk of serious adverse effects. However, the utility and safety of slower-than-recommended titration of clozapine remain unclear. Consequently, we aimed to investigate the clinical utility and safety of slower-than-recommended titration of clozapine for treatment-resistant schizophrenia. We conducted a retrospective chart review of 152 inpatients with treatment-resistant schizophrenia who had been newly started on clozapine in a tertiary psychiatric public hospital between April 2012 and March 2018. The primary outcome was clozapine continuation for the first 18 weeks. We performed multivariate logistic regression to identify the association between the rate of clozapine dose titration and clozapine continuation for the first 18 weeks. Among the 152 inpatients, 122 (80%) could continue clozapine for the first 18 weeks. There was no significant association between the rate of clozapine dose titration and clozapine continuation for the first 18 weeks (adjusted odds ratio 1.23; 95% CI 0.29-5.26; p = 0.78). Our findings indicate that slower-than-recommended titration of clozapine may not improve toward clozapine continuation for the first 18 weeks. Therefore, it may not be a beneficial option in terms of safe clozapine continuation when starting clozapine for treatment-resistant schizophrenia.

Clozapine-associated neutropenia following augmentation with sodium valproate

Clozapine is gold standard for the management of treatment-resistant schizophrenia. It can offer life-changing symptom reduction where other antipsychotics have failed, and for these patients, treatment with clozapine should be maintained, if in any possible way. However, treatment with clozapine comes with a risk of developing potentially fatal adverse reactions, for example, severe neutropenia or agranulocytosis, in which case, treatment must be discontinued. Here, we present a case of clozapine-related neutropenia that commenced after the addition of sodium valproate. A subsequent re-challenge to clozapine resulted in severe neutropenia and led to the permanent cessation of clozapine treatment. The patient had been tolerating clozapine for more than a year before the addition of sodium valproate. The awareness of an interaction between clozapine and sodium valproate could help reduce the risk of clozapine-induced neutropenia and subsequent clozapine discontinuation.

Late-Onset Neutropenia in Long-Term Clozapine Use and Its Management Utilizing Prophylactic G-CSF

This case outlines recurrent neutropenia after fourteen years of successful clozapine use. The patient has a diagnosis of treatment-resistant schizophrenia which has been complicated by sensitivity to side effects of haloperidol and past failure of antipsychotics to manage her symptoms. It was necessary for our patient to follow a complicated treatment path involving close monitoring of blood levels, admissions, the initiation of lithium and the regular use of filgrastim (Neupogen), granulocyte colony stimulating factor (G-CSF). Following a failure of rescue filgrastim to increase her neutrophil levels, a management protocol was designed with input from the on-site hematology team. This protocol involved the use of filgrastim on a regular prophylactic basis. This management plan has worked for the patient who has been able to continue use of clozapine and has not suffered from any neutropenic episodes in over six months.

Need to bleed? Clozapine haematological monitoring approaches a time for change

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

Clozapine-induced bicytopenia: An unusual side effect

Agranulocytosis is a rare documented side effect of clozapine which can be associated with grave consequences. When it is associated with other blood dyscrasia, prognosis worsens further. In literature, there are very few cases of pancytopenia and bicytopenia caused by clozapine. We present a case of bicytopenia (reduced white and red blood cells' counts) caused by clozapine within a month of therapy and complicated by a Klebsiella pneumoniae infection. Patient improved in 3 weeks after stopping clozapine along with medical management in the Intensive Care Unit. Such side effects, though rare, can be life threatening and warrants intermittent complete blood monitoring besides regular assessment of granulocytes and neutrophils when any patient is prescribed clozapine.

Re-titration rates after clozapine-induced neutropenia or agranulocytosis: A case report and literature review

Clozapine-induced neutropenia occurs in 3-5% of individuals treated with clozapine. Current US guidelines require interruption of clozapine when the absolute neutrophil count (ANC) drops below 1000 cells/mm3. There is minimal available guidance for what dosing schedule to use when restarting clozapine after an episode of neutropenia. Here, we present a case of a 50-year-old Caucasian female with a history of schizoaffective disorder who was successfully rechallenged on clozapine one month after developing clozapine-induced neutropenia (ANC 600 cells/mm3). To understand published re-titration rates of clozapine after neutropenia, we conducted a literature review using a using the PubMed database and found only seven case reports that unambiguously reported a clozapine dosing schedule during re-challenge. All were successful except one, a case of clozapine rechallenge after agranulocytosis. Including this case presentation, six out of eight cases restarted clozapine more cautiously than recommended by the US guidelines for a new clozapine initiation. We cannot comment what role a slower or more rapid titration plays in a successful rechallenge after neutropenia with the available evidence. We encourage researchers to publish their dosing schedule in detail after an episode of neutropenia or agranulocytosis.

Clozapine and blood dyscrasia

Clozapine is an effective antipsychotic medication but is associated with agranulocytosis, neutropenia and leucopenia. The reintroduction of clozapine improved management of treatment-resistant schizophrenia, yet resulted in a paradoxical situation whereby the risk of blood dyscrasias is rigorously managed but other adverse effects (e.g. seizures, cardiovascular complications) are less well monitored. Monitoring of weight, lipids, plasma glucose and other metabolic parameters is recommended. There is also a need to reconsider routine haematological monitoring with other medications associated with blood dyscrasia (e.g. phenothiazines, carbamazepine). In particular, individuals who develop clozapine-induced blood dyscrasia may require haematological monitoring during treatment with other antipsychotics.

Successful clozapine re-challenge in a patient with three previous episodes of clozapine-associated blood dyscrasia

A case is presented of a 30-year-old female with treatment-resistant schizoaffective disorder who was referred to a tertiary-level specialist psychosis service. We describe the history of clozapine trials and associated episodes of agranulocytosis and neutropenia, followed by the successfully tolerated third clozapine re-challenge within our service.

DECLARATION OF INTEREST

None.

COPYRIGHT AND USAGE

© The Royal College of Psychiatrists 2017. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) license.

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.

Clozapine Rechallenge After Neutropenia or Leucopenia

To rechallenge with clozapine for a patient who previously has experienced neutropenia or leucopenia or during clozapine treatment is a difficult clinical decision. Herein, we analyzed the results of such a rechallenge in 19 patients. We analyzed all the reports, from the database of the pharmacovigilance department of the Argentine National Administration of Drugs, Foods, and Medical Devices, of patients who were rechallenged with clozapine after a leucopenia or a neutropenia. Nineteen cases of rechallenge after leucopenia or neutropenia were reported between 1996 and 2014. One third of the patients re-exposed to clozapine developed a new hematologic adverse reaction. The second blood dyscrasia was less severe in 83% of the cases and had a shorter median latency as compared with the first (8 weeks vs 182 weeks, P = 0.0045). There were no significant differences for demographic and clinical characteristics of patients who developed a second dyscrasia as compared with those who did not. The present study shows that almost 70% of the patients rechallenged with clozapine after a leucopenia or a neutropenia did not develop a new hematological adverse effect, whereas the remaining 30% had a faster but less serious neutropenia.

Late Onset Agranulocytosis with Clozapine Associated with HLA DR4 Responding to Treatment with Granulocyte Colony-stimulating Factor: A Case Report and Review of Literature

Agranulocytosis as a side effect of clozapine has been reported to be associated with initial phases of treatment, i.e., first six months. Agranulocytosis with clozapine during the initial phases of treatment has been linked to genetic vulnerability in the form of variations in the human leukocyte-antigen haplotypes. However, there is limited literature on late onset agranulocytosis with clozapine and this has very rarely been linked to human leukocyte-antigen haplotypes vulnerability. In this report we review the existing data on late onset agranulocytosis with clozapine and describe the case of a young man, who developed agranulocytosis with clozapine after 35 months of treatment and was found to have genetic vulnerability in form of being positive for HLA DR4. This case highlights underlying autoimmune immune mechanism in clozapine-induced agranulocytosis and the need for frequent blood count monitoring on clozapine even after the initial 6 months of starting treatment especially in patients with genetic vulnerability to develop this condition.

Continuing clozapine treatment with lithium in schizophrenic patients with neutropenia or leukopenia: brief review of literature with case reports

OBJECTIVE

Clozapine is a second-generation antipsychotic used for treatment-resistant schizophrenia. Despite its effectiveness, clozapine is largely underused due to serious side effects such as leukopenia or neutropenia. We aimed to review whether to continue, discontinue or rechallenge clozapine treatment after such haematological side effects.

METHODS

We reviewed and summarized the literature on the use of clozapine, how to deal with its side effects, and suitable options in case of any haematological problems. Then, we described several cases successfully treated with clozapine and lithium after development of neutropenia or leukopenia.

RESULTS

We present three patients with treatment-resistant schizophrenia. While they had demonstrated poor response to multiple antipsychotic trials, clozapine was started. Clozapine induced neutropenia; or leukopenia developed in some cases that was successfully reversed after lithium onset. Increased serious side effects related with coprescription of lithium and clozapine were not observed.

CONCLUSION

Lithium increases neutrophil and total white blood cell count as a side effect that may be useful in patients who develop neutropenia or leukopenia while being treated with clozapine.

Worldwide Differences in Regulations of Clozapine Use

Clozapine remains the drug of choice for treatment-resistant schizophrenia. As a consequence of its long history and complex pharmacology, we suspected wide variation in the regulations of clozapine use across different countries. The summaries of product characteristics (SPCs) from clozapine manufacturers, as well as local and national guidelines in the following selected countries, were reviewed: China, Denmark, Ireland, Japan, The Netherlands, New Zealand, Romania, the UK and the US. Clozapine is available as tablets in all countries, as an oral suspension in all included countries, with the exception of Japan and Romania, as orally disintegrating tablets in the US and China, and as an injectable in The Netherlands. General practitioner prescribing is only available in The Netherlands, New Zealand, the UK and the US, although with some restrictions in some of the countries. In Ireland and China, clozapine is only dispensed through hospital pharmacies. Hematological monitoring is mandatory in all countries but varies substantially in frequency, e.g. in Denmark hematologic monitoring is mandatory weekly for 18 weeks, followed by monthly monitoring, compared with Japan where blood work is required weekly for 26 weeks, followed by biweekly hematologic monitoring thereafter. In most included countries, with the exception of Denmark, Romania and The Netherlands, the manufacturer provides a mandatory hematological monitoring database, and dispensing of clozapine is not permissible without acceptable white blood count and absolute neutrophil count results. Local guidelines in New Zealand recommend echocardiography and routine troponin during the initial phases of treatment with clozapine. Regulations of clozapine vary widely with regard to rules of prescribing and monitoring. A worldwide update and harmonization of these regulations is recommended.

Clozapine induced pancytopenia leading to severe sepsis: an unusual early complication

BACKGROUND

Clozapine is a second generation antipsychotic used to treat resistant schizophrenia and other psychotic illnesses. Leucopenia or agranulocytosis is a rare side effect of this drug. Pancytopenia is an extremely rare side effect of clozapine and literature review showed only one such case in where the pancytopenia developed several months after starting clozapine together with other antipsychotic drugs.

CASE PRESENTATION

A 26-year-old Sri Lankan male was admitted with fever for 3 days. Apart from generalized body aches there were no other significant symptoms. His blood counts showed pancytopenia. He was being treated for a resistant schizophrenia and clozapine was started only 4 weeks before. Common causes for pancytopenia were excluded, and a diagnosis of clozapine induced pancytopenia was made. He was managed in the intensive care unit with broad spectrum antibiotics, antifungals and granulocyte colony stimulating factors. He made a complete recovery after 4 weeks.

CONCLUSION

This is a rare and probably the first reported case of early onset clozapine induced pancytopenia complicated by severe sepsis recovering completely.

Establishing the characteristics of an effective pharmacogenetic test for clozapine-induced agranulocytosis

Clozapine is the only evidence-based therapy for treatment-resistant schizophrenia, but it induces agranulocytosis, a rare but potentially fatal haematological adverse reaction, in less than 1% of users. To improve safety, the drug is subject to mandatory haematological monitoring throughout the course of treatment, which is burdensome for the patient and one of the main reasons clozapine is underused. Therefore, a pharmacogenetic test is clinically useful if it identifies a group of patients for whom the agranulocytosis risk is low enough to alleviate monitoring requirements. Assuming a genotypic marker stratifies patients into a high-risk and a low-risk group, we explore the relationship between test sensitivity, group size and agranulocytosis risk. High sensitivity minimizes the agranulocytosis risk in the low-risk group and is essential for clinical utility, in particular in combination with a small high-risk group.

Clozapine-Induced Late Agranulocytosis and Severe Neutropenia Complicated with Streptococcus pneumonia, Venous Thromboembolism, and Allergic Vasculitis in Treatment-Resistant Female Psychosis

Clozapine is a second-generation antipsychotic agent from the benzodiazepine group indicated for treatment-resistant schizophrenia and other psychotic conditions. Using clozapine earlier on once a case appears to be refractory limits both social and personal morbidity of chronic psychosis. However treatment with second-generation antipsychotics is often complicated by adverse effects. We present a case of a 33-year-old Caucasian woman with a 25-year history of refractory psychotic mania after switching to a 2-year clozapine therapy. She presented clozapine-induced absolute neutropenia, agranulocytosis, which were complicated by Streptococcus pneumonia and sepsis. Clozapine-induced thromboembolism of the common femoral and right proximal iliac vein, as well as allergic vasculitis, was diagnosed. She achieved full remission on granulocyte-colony stimulating factor and specific antibiotic treatment. Early detection of severe clozapine-induced absolute neutropenia and agranulocytosis enabled the effective treatment of two among its most severe complications. Additional evidence to the previously reported possible causal relation between clozapine and venous thromboembolism is offered. Finally, clozapine-induced allergic vasculitis is confirmed as a late adverse effect of clozapine therapy.

Making clozapine safer: current perspectives on improving its tolerability

ABSTRACT: 

Clozapine is the gold standard treatment for refractory schizophrenia and its benefits are supported by an evidence base. Yet, it remains largely underused in clinical practice. This is because of low acceptability from patients and reluctance in initiating, and delays in prescribing by clinicians. A major deterrent is often the common adverse reactions, which clinicians are apt to disregard, focusing instead on the severe but rare complications of clozapine, such as agranulocytosis. We will review recent evidence on increasing the prescription of clozapine, focusing particularly on improving the safety and tolerability of the drug, by effective management of its adverse effects. The adverse effects considered in our review include sedation, seizures, myoclonus, hypersalivation, nausea, constipation, hypotension, hypertension, tachycardia, myocarditis, cardiomyopathy, weight gain, diabetes, dyslipidemia, neutropenia, agranulocytosis, fever, nocturnal enuresis and obsessive–compulsive symptoms. We will also discuss strategies to enable successful clozapine rechallenge after severe cardiac and hematological adverse reactions, thus aiming to offer patients their best chance at recovery.

The neuroimmunology of schizophrenia

Schizophrenia (SCZ) is a polygenic, multi-factorial disorder and a definitive understanding of its pathophysiology has been lacking since it was first described more than a century ago. The predominant pharmacological approach used to treat SCZ is the use of dopamine receptor antagonists. The fact that many patients remain symptomatic, despite complying with medication regimens, emphasises the need for a more encompassing explanation for both the causes and treatment of SCZ. Recent neuroanatomical, neurobiological, environmental and genetic studies have revived the idea that inflammatory pathways are involved in the pathogenesis of SCZ. These new insights have emerged from multiple lines of evidence, including the levels of inflammatory proteins in the central nervous system of patients with SCZ and animal models. This review focuses on aberrant inflammatory mechanisms present both before and during the onset of the psychotic symptoms that characterise SCZ and discusses recent research into adjunctive immune system modulating therapies for its more effective treatment.

Continuing clozapine with granulocyte colony-stimulating factor in patients with neutropenia

BACKGROUND

The current guidelines dictate that clozapine should be stopped following the emergence of neutropenia. Various alternative approaches have been tried in the past, among them one rarely used alternative being to continue treatment with clozapine with coprescription of granulocyte colony-stimulating factor (G-CSF).

AIM AND METHOD

In this case series we aim to describe the treatment and progress of a number of patients in a secure psychiatric hospital in the UK. These patients were restarted on clozapine in combination with G-CSF, in spite of previous neutropenia associated with clozapine treatment.

DISCUSSION AND CONCLUSION

We hope that this case series will raise the profile of a potentially effective alternative to discontinuing clozapine after neutropenia.

Management and prevention of agranulocytosis in patients receiving clozapine

Clozapine is an antipsychotic associated with superior efficacy compared to other atypical antipsychotics in the treatment of schizophrenia. However, clozapine use is limited due to its association with a rare but potentially fatal adverse effect, agranulocytosis. Patients receiving clozapine therapy require frequent monitoring of white blood cell (WBC) and absolute neutrophil counts (ANC). This article reviews the monitoring parameters for patients receiving clozapine therapy, and the management and prevention of clozapine-associated agranulocytosis.

Pharmacogenetics: a reality or misplaced optimism?

The paper aims to review current evidence that supports the application of genetic information in the management and use of psychotropic medication. Although the importance of an individual's genetic makeup in the metabolism of drugs has been known for at least 50 years, it is only recently that such information is finding clinical application. A literature review of recent studies suggest that there are clear variations in the way people respond to psychotropic medication. These variations can be seen across racial and ethnic lines, and are genetically determined. The hope is that, in future we will be able to use genetic information to predict which patient will benefit from which drug and at what dose. In other fields of health care such as anticoagulant therapy, the application of pharmacogenetics is now established in routine clinical care. Several psychiatric pharmacogenetic tests are currently available, including tests for the determination of metabolic status, risk of agranulocytosis and metabolic syndrome, and selection of beneficial medications. Since nurses are the centrepiece of mental health care, these advances are likely to alter significantly future mental health nurse education and practice.

Risk factors for neutropenia in clozapine-treated children and adolescents with childhood-onset schizophrenia

OBJECTIVE

The purpose of this study was to retrospectively analyze rates of neutropenia and risk factors for neutropenia in hospitalized children and adolescents treated with clozapine.

METHODS

A retrospective chart review was conducted for all patients who received clozapine at any time during a hospitalization at the National Institute of Mental Health (NIMH) between 1990 and 2011. All patients satisfied screening criteria for the NIMH childhood-onset schizophrenia study, including onset of psychosis before the age of 13 years. Absolute neutrophil count (ANC) values recorded during inpatient hospitalization were extracted for 87 eligible patients with a mean age of 13.35±2.46 years at hospitalization and a mean length of stay of 117±43 days.

RESULTS

Mild neutropenia only (lowest ANC<2000/mm3 but>1500/mm3) was observed in 27 (31%) patients and moderate neutropenia (any ANC<1500/mm3) was observed in 17 (20%) patients. There were no cases of agranulocytosis or severe infection. Significant risk factors for mild neutropenia compared with no hematologic adverse effects (HAEs) were male gender (p=0.012) and younger age (p<0.001). Male gender was also a significant risk factor for moderate neutropenia compared with no HAEs (p=0.003). If a child of African American ethnicity developed neutropenia during hospitalization at all that child was significantly more likely to develop moderate neutropenia than mild neutropenia only (p=0.017). African American boys had the highest rate of moderate neutropenia at 47%. Sixteen of the 17 patients exhibiting moderate neutropenia were successfully treated with clozapine by the time of discharge; 8 of these 16 required adjunctive lithium carbonate administration to maintain ANC>2000/mm3.

CONCLUSIONS

Our study shows that the rates of neutropenia in clozapine-treated children and adolescents are considerably higher than in the adult population. Younger age, African American ethnicity, and male gender were significant risk factors. These are also risk factors for benign neutropenia in healthy children and adolescents. Despite these high rates of neutropenia, all but one of the patients with neutropenia during hospitalization were successfully discharged on clozapine.

Immunomodulatory effects of clozapine and their clinical implications: what have we learned so far?

Clozapine remains the drug of choice for treatment resistant schizophrenia, but is associated with potentially life threatening side effects, including agranulocytosis and myocarditis. Immunological mechanisms may be involved in the development of these side effects or in the unique antipsychotic efficacy in subgroups of schizophrenia patients. This systematic review presents the immunomodulatory effects of clozapine from human in vitro and in vivo studies and relates these findings to the developments of adverse and therapeutic effects of clozapine. Several studies confirm the immunomodulatory actions of clozapine, but only few studies investigated their relationship to the unique adverse and therapeutic effects of clozapine. During the first month of clozapine treatment, up to 50% of patients develop fever and flu like symptoms, which is seemingly driven by increased cytokines. Within the same time period, the risk of side-effects with a suspected immunological mechanism peaks. Patients developing fever during the first weeks of treatment should have a thorough physical examination, and measurements of white blood cell count, absolute neutrophil count, ECG, C-reactive protein, creatinine kinase, and troponin to exclude infection, agranulocytosis, myocarditis and neuroleptic malignant syndrome. To what degree the unique antipsychotic efficacy of clozapine in subgroups of schizophrenia patients is related to its immunomodulatory effects has not been studied. Research relating the immunomodulatory actions of clozapine and its early markers to clinically relevant adverse and therapeutic outcomes is hoped to provide new leads for the understanding of the pathophysiology of schizophrenia and aid the development of novel treatment targets.

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.

When can patients with potentially life-threatening adverse effects be rechallenged with clozapine? A systematic review of the published literature

BACKGROUND

Clozapine is widely prescribed for treatment refractory patients with schizophrenia, but its use is limited by potentially life threatening adverse effects. Rechallenge after these complications has been occasionally attempted in patients with severe psychotic symptoms.

OBJECTIVE

To review the outcome of clozapine rechallenge after potentially life threatening adverse effects.

METHODS

Electronic, all-language, literature search (1972-2011) followed by demographic and clinical data extraction. The outcome of rechallenge was considered favorable when the lower bound of the 95% confidence interval (CI) of the proportion of patients who could continue clozapine was >50%.

RESULTS

Altogether, 138 patients (mean age: 36.3years, 65.7% male, 57.6% Caucasian, virtually all with schizophrenia spectrum diagnosis) underwent clozapine rechallenge after developing neutropenia (n=112), agranulocytosis (n=15), neuroleptic malignant syndrome (NMS) (n=5), myocarditis (n=4), pericarditis (n=1) and lupus erythematosus (n=1). Rechallenge strategies were heterogeneous and not systematically evaluated. Clozapine rechallenge was successful in 78/112 patients (69.6%, CI: 60.6-77.4) after neutropenia, 3/15 (20%, CI: 7.1-45.2) after agranulocytosis, 5/5 (100%, CI: 56-100) after NMS, 3/4 (75%, CI: 30-95) after myocarditis, 1/1 after pericarditis, and 0/1 after clozapine-induced lupus. Successfully rechallenged patients were followed for 16-96weeks. None of the rechallenged patients died.

CONCLUSIONS

Although controlled studies are clearly needed, using a priori, confidence interval-based criteria, case reports/series suggest that in refractory patients who benefited from clozapine, careful rechallenge can be considered after neutropenia and NMS, but not after agranulocytosis and myocarditis.

The importance of the recognition of benign ethnic neutropenia in black patients during treatment with clozapine: case reports and database study

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