• Korean Journal of Schizophrenia Research
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• v.24 no.1
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• pp.1-7
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• 2021

Clozapine is the first and most effective atypical antipsychotic drug for treatment-resistant schizophrenia (TRS). After withdrawal of clozapine due to concerns of agranulocytosis, clozapine was reintroduced with a comprehensive safety monitoring system, the clozapine patient monitoring system (CPMS). The reintroduction was a response to the pressure from psychiatrists and patients with TRS and their families. Clozapine is still the best single agent for the treatment of TRS. However, approximately 30% of patients with TRS still show psychotic symptoms. In patients with clozapine-resistant schizophrenia (CRS), augmentation of other antipsychotic agents could be considered after a thorough evaluation of proper clozapine treatment. In this review, the status of clozapine in patients with TRS and CRS will be discussed.

• Korean Journal of Schizophrenia Research
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• v.23 no.2
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• pp.45-50
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• 2020

Schizophrenia is one of serious mental illnesses and is often described as a heterogeneous disorder. Approximately one-third of schizophrenia cases are treatment-resistant schizophrenia (TRS). The aim of this study was to review the definitions and clinical features of TRS. Though it was found that the criteria for TRS were considerably diverse, the Treatment Response and Resistance in Psychosis (TRRIP) consensus criteria were recently introduced. According to the TRRIP criteria, TRS should be suspected if symptoms persist alongside psychotic symptoms despite sufficient treatment for ≥12 weeks, or two or more symptoms persist significantly for ≥6 weeks. The clinical characteristics of TRS includes an earlier age of onset, more severe and familial form, possibly more rural residence, unlikely association with male sex, and an increase in cognitive deficits.

• Journal of Korean Neuropsychiatric Association
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• v.57 no.3
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• pp.230-234
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• 2018

A large proportion of patients with schizophrenia show a poor response to first-line antipsychotic drugs, which is termed treatment-resistant schizophrenia. Previous studies found that a different neurobiology might underlie treatment-resistant schizophrenia, which necessitates the development of different therapeutic approaches for treating treatment-resistant schizophrenia. This study reviewed previous studies on the pathophysiology of treatment-resistant schizophrenia and the pharmacological intervention, and forthcoming investigations of treatment-resistant schizophrenia are suggested.

• Korean Journal of Schizophrenia Research
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• v.24 no.2
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• pp.52-59
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• 2021

Objectives: Recent studies have reported that delayed initiation of clozapine can affect clinical response in patients with treatment-resistant schizophrenia (TRS). This study aimed to explore the relationship between delayed initiation of clozapine and acute treatment response. Methods: Sixty-five inpatients with TRS who started clozapine for the first time were included through a retrospective chart review. Acute treatment response was defined as a 30% reduction in the Positive and Negative Syndrome Scale score or a Clinical Global Impression of Improvement score of 1 (very much improved) or 2 (much improved) at 4 weeks after initiating clozapine. Results: After meeting the TRS criteria, the mean delay for initiating clozapine was approximately 13.8 months. The delay was shorter in patients who showed a better response to clozapine in logistic regression analysis (p=0.037). Conclusion: Our findings suggest that reducing the delay in initiating clozapine increases the effectiveness of clozapine in patients with TRS.

• Korean Journal of Schizophrenia Research
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• v.23 no.2
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• pp.51-57
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• 2020

Treatment-resistant schizophrenia (TRS) has been defined as the persistence of positive symptoms despite two or more trials of antipsychotic medication of adequate dose and duration. TRS is a serious clinical problem and occurs in approximately 30% of patients with schizophrenia. It is important that patients who do not adequately respond to antipsychotics be reevaluated to exclude or address causes other than non-responsiveness to medication, that is, the possibility of pseudo-resistance. In particular, non-adherence to oral antipsychotic treatment should be monitored to rule out pseudo-resistant cases of TRS. Moreover, patients with TRS who take their medication as required may have subtherapeutic antipsychotic plasma levels, secondary to pharmacokinetic factors. In this paper, we review the concept and exclusion of pseudo-resistance, especially owing to non-adherence or pharmacokinetic factors, and present methods to enhance drug adherence.

• Korean Journal of Psychosomatic Medicine
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• v.30 no.2
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• pp.66-72
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• 2022

Clozapine is accepted as the "gold standard" antipsychotics for treatment-resistant schizophrenia. Clozapine rarely causes extrapyramidal syndrome and tardive dyskinesia, which are common with other antipsychotics, and only a transient elevation of hyperprolactinemia has been reported. Despite such clinical usefulness, there are limitations to the use of clozapine due to adverse drug reactions (ADR). Fever is a common in adverse drug reactions associated with clozapine. At initiation of clozapine most fatal ADR such as agranulocytosis and neuroleptic malignant syndrome associated with fever, in which case clozapine should be discontinued immediately. However, as benign causes of fever are much more frequent than life-threatening ADR, clozapine should not be discontinued unconditionally in the event of fever during clozapine initiation. In addition, fever may occur at any time during the maintenance of clozapine treatment. In particular, since the risk of pneumonia does not decrease over time, and clozapine has a higher risk of pneumonia than other antipsychotic drugs, it is recommended to adjust clozapine dosage through therapeutic drug monitoring.