A descriptive study of 10-year clozapine use from the nationwide database in Japan

When, Why and How to Re-challenge Clozapine in Schizophrenia Following Myocarditis

Clozapine-induced myocarditis (CIM) is among the most important adverse events limiting the use of clozapine as the most effective treatment for schizophrenia. CIM necessitates the immediate termination of clozapine, often resulting in its permanent discontinuation with considerable detrimental effects on patients' psychopathology and long-term outcome. Consequently, a clozapine re-challenge after CIM is increasingly regarded as a viable alternative, with published reports indicating a success rate of approximately 60%. However, published cases of re-challenges after CIM remain limited. Here, we provide a narrative review of the current state of research regarding the epidemiology, pathophysiology, risk factors, diagnosis and clinical management of CIM as well as a synthesis of current recommendations for re-challenging patients after CIM. This includes a step-by-step guide for this crucial procedure based on the current evidence regarding the pathophysiology and risk factors for CIM. Slow dose titration regimes and addressing risk factors including concomitant valproate and olanzapine are crucial both to prevent CIM and to ensure a safe and successful re-challenge. Furthermore, we discuss the utility of C-reactive protein, troponin, N-terminal-pro hormone and brain natriuretic peptide, therapeutic drug-monitoring and cardiac magnetic resonance imaging for CIM screening and diagnosis as well as for post-CIM re-challenges.

Data Mining for Risks of Clozapine Side Effects, Including Neutropenia, Associated with Lithium Carbonate Administration: Analysis Using the Japanese Adverse Drug Event Report Database

BACKGROUND AND OBJECTIVE

Clozapine use is associated with development of neutropenia, and lithium carbonate may be co-administered to reduce this risk; however, this has not yet been adequately investigated. The present study examined whether lithium administration is associated with the risks of clozapine side effects, including neutropenia.

METHODS

Data on patients taking clozapine, extracted from the Japanese Adverse Drug Event Report (JADER) database, were analyzed. Patients who developed clozapine side effects were identified by the Standardized Medical Dictionary for Regulatory Activities Queries. The relationship between the use of lithium and risk of clozapine side effects was examined using logistic regression analysis.

RESULTS

The use of lithium was reported in 530 out of 2,453 clozapine users. Hematopoietic leukopenia, convulsion, and noninfectious myocarditis/pericarditis developed in 109, 87, and seven lithium-treated patients, and in 335, 173, and 62 untreated patients, respectively. Univariate analysis showed no relationship between lithium administration and the risks of hematopoietic leukopenia (adjusted odds ratio (aOR) 1.11; 95% confidence interval (CI) 0.98-1.25), and the association with the risks of convulsion (aOR 1.41; 95% CI 1.23-1.62) and noninfectious myocarditis/pericarditis (aOR 0.63; 95% CI 0.43-0.94). Multivariate analysis revealed that lithium use was independently associated with the risks of convulsion (aOR 1.40; 95% CI 1.21-1.60) and noninfectious myocarditis/pericarditis (aOR 0.62; 95% CI 0.41-0.91).

CONCLUSION

The risks of seizure and myocarditis, but not of neutropenia, in clozapine-treated patients may be altered by lithium. Although the JADER database is based on spontaneous reporting, the present results warrant further study.

Development of individual fitness score for conformity of prescriptions to the "Guidelines For Pharmacological Therapy of Schizophrenia"

AIMS

The Guidelines for the Pharmacotherapy of Schizophrenia were established to improve the quality of medical care, and the EGUIDE project was conducted to train clinicians on guideline usage. A quality indicator (QI) was established to measure the prevalence of the guidelines, and a survey was conducted, which revealed a gap between the guidelines and actual clinical practice (evidence-practice-gap). The purpose of this study was to develop an individual fitness score (IFS) formula that expresses the degree to which prescribers adhere to the Guidelines for Pharmacological Therapy of Schizophrenia in a simple manner, and to determine the validity of this formula from a survey of the prescriptions of the EGUIDE project participants'.

METHODS

To establish appropriate scores, members discussed the proposed formula and then voted on them. The IFS formula developed was set up so that antipsychotic monotherapy would be given 100 points, with points deducted if concomitant or adjunctive antipsychotic medications were used, and a minimum score of 0. To validate this formula, prescriptions of hospitalized schizophrenic patients at admission and at discharge were scored and compared.

RESULT

IFS points vary and ranged from 0 to100. The average pre-admission score for all subjects was 45.6, and the average score at discharge was 54, those were significantly higher during discharge.

CONCLUSIONS

We developed an IFS formula, a tool to easily visualize the degree to which current prescriptions conform to the guidelines for the pharmacological treatment of schizophrenia.

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.

Distinctive pattern of neutrophil count change in clozapine-associated, life-threatening agranulocytosis

The wider use of clozapine is limited by the risk of agranulocytosis and the associated requirement for monitoring of neutrophil counts. We searched local electronic patient records for cases of agranulocytosis occurring during clozapine treatment during the period 2007–2020. We found 23 episodes recorded as agranulocytosis in clozapine patients. Of these, nine met pre-defined criteria and were considered episodes of life-threatening agranulocytosis (LTA). These episodes of clozapine-induced LTA exhibited a distinct pattern of continuous and rapid neutrophil count decline to zero or near zero. Mean time for neutrophils to fall from ANC > 2 to ANC <0.5 × 10⁹/L was 8.4 days (range 2–15 days). Each event was also characterised by a prolonged nadir and delayed recovery (range 4–16 days). Non-LTA episodes were, in contrast, brief and benign. We conclude that an important proportion of cases of agranulocytosis identified in people prescribed clozapine are not life-threatening and may not even be clozapine-related. Monitoring schemes should aim to identify true clozapine-induced LTA as opposed to threshold-defined nominal agranulocytosis. Genetics studies might benefit from examining associations with clozapine-induced LTA rather than with recorded cases of agranulocytosis or neutropenia.

Safety profile of clozapine: Analysis using national registry data in Japan

Clozapine is the only effective antipsychotic drug used for the treatment of treatment-resistant schizophrenia. Although it has been shown that the frequency of clozapine use is very low in Japan, our previous study revealed that the number of clozapine prescriptions has been increasing in recent years, and that risk factors leading to discontinuation of clozapine were also identified as age ≥40 years, poor tolerability to olanzapine, previous treatment with clozapine, and white blood cell count <6000/mm³. The main cause for discontinuation of clozapine is the occurrence of a wide range of adverse events, including neutropenia/leukopenia and fatal cardiac disorders. In this study, we analyzed the physical details and backgrounds of patients with adverse events that led to clozapine discontinuation using a national registry database of more than 8000 Japanese patients. The physical adverse events that led to discontinuation of clozapine were neutropenia/leukopenia, glucose intolerance, cardiac disorders, gastrointestinal disorders, neuroleptic malignant syndrome, pleurisy, pulmonary embolism, sedation/somnolence, and seizures. Neutropenia/leukopenia had the highest incidence (5.0%). Neutropenia/leukopenia and cardiac disorders tended to occur early in the treatment period, indicating the need for careful monitoring for these adverse events in the early stages of clozapine treatment. Gastrointestinal disorders occurred over a long period of time, suggesting the need for careful observation during the maintenance period. The data obtained in our study will lead to the optimal and safe use of clozapine treatment.