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Annals of Hematology Nov 2020Wider use of clozapine, one of the most effective antipshychotic drugs, is precluded by its propensity to cause agranulocytosis. Currently, clozapine is used for... (Review)
Review
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.
Topics: Black People; Clozapine; Humans; Neutropenia; Risk Factors
PubMed: 32815018
DOI: 10.1007/s00277-020-04215-y -
Advances in Pharmacology (San Diego,... 2018Schizophrenia is a heterogenous and severe neuropsychiatric disorder that affects nearly 1% of the population worldwide. Antipsychotic drugs are the mainstay of... (Review)
Review
Schizophrenia is a heterogenous and severe neuropsychiatric disorder that affects nearly 1% of the population worldwide. Antipsychotic drugs are the mainstay of treatment, but not all patients with schizophrenia respond to treatment with these agents. Clozapine, the first atypical antipsychotic, is a highly effective medication for patients with schizophrenia who do not respond to other antipsychotics. Although clozapine tends not to produce extrapyramidal symptoms, other side effects of the drug (e.g., agranulocytosis, myocarditis, seizures) limit its widespread use. This chapter reviews clozapine's unique clinical effects and unusual pharmacological profile. In addition to its effects in treatment-resistant schizophrenia, clozapine has been shown to decrease suicidality, which occurs at an increased rate in patients with schizophrenia. Still preliminary, but consistent data, also suggest that clozapine limits substance use in these patients, an important effect since substance use disorders are common in patients with schizophrenia and are associated with a poor outcome, including an increased risk for suicide and poor response to treatment. We have suggested, from animal studies, that clozapine's apparent ability to limit substance use may occur through its actions as a weak dopamine D2 receptor antagonist, a potent norepinephrine α-2 receptor antagonist and a norepinephrine reuptake inhibitor. Using animal models, we have built combinations of agents toward creation of safer clozapine-like drugs to reduce substance use in these patients. Future research into the mechanisms of action of clozapine toward the development of safe clozapine-like agents is of great public health importance.
Topics: Animals; Antipsychotic Agents; Clozapine; Humans; Schizophrenia; Substance-Related Disorders; Suicide
PubMed: 29413518
DOI: 10.1016/bs.apha.2017.09.009 -
The Journal of Clinical Psychiatry Sep 2021reatment-resistant schizophrenia (TRS) represents a major clinical challenge. The broad definition of TRS requires nonresponse to at least 2 sequential antipsychotic... (Review)
Review
reatment-resistant schizophrenia (TRS) represents a major clinical challenge. The broad definition of TRS requires nonresponse to at least 2 sequential antipsychotic trials of sufficient dose, duration, and adherence. Several demographic, clinical, and neurologic predictors are associated with TRS. Primary (or early) TRS is present from the beginning of therapy, while patients with secondary (or later-onset) TRS initially respond to antipsychotics but become resistant over time, often after relapses. Guidelines worldwide recognize clozapine as the most effective treatment option for TRS, but clozapine is underused due to various barriers. Importantly, studies indicate that response rates are higher when clozapine is initiated earlier in the treatment course. Side effects are common with clozapine, particularly in the first few weeks, but can mostly be managed without discontinuation; they do require proactive assessment, intervention, and reassurance for patients. Furthermore, plasma leucocyte and granulocyte levels must be monitored weekly during the first 18-26 weeks of treatment, and regularly thereafter, according to country regulations. Therapeutic drug monitoring of clozapine trough plasma levels is helpful to guide dosing, with greatest efficacy at plasma clozapine levels ≥350 µg/L, although this level is not universal. Notably, plasma clozapine levels are generally greater at lower doses in nonsmokers, patients with heavy caffeine consumption, in women, in obese people, in those with inflammation (including COVID-19 infection), and in older individuals. Earlier and broader use of clozapine in patients with TRS is an important measure to improve outcomes of patients with this most severe form of the illness.
Topics: Antipsychotic Agents; Clozapine; Drug Resistance; Drug Tolerance; Female; Humans; Male; Schizophrenia
PubMed: 34496461
DOI: 10.4088/JCP.MY20096AH1C -
Psychotherapy and Psychosomatics 2020Using Richardson and Davidson's model and the sciences of pharmacokinetics and clinical pharmacopsychology, this article reviewed the: (1) poor life expectancy... (Review)
Review
Using Richardson and Davidson's model and the sciences of pharmacokinetics and clinical pharmacopsychology, this article reviewed the: (1) poor life expectancy associated with treatment-resistant schizophrenia (TRS), which may be improved in patients who adhere to clozapine; (2) findings that clozapine is the best treatment for TRS (according to efficacy, effectiveness and well-being); and (3) potential for clozapine to cause vulnerabilities, including potentially lethal adverse drug reactions such as agranulocytosis, pneumonia, and myocarditis. Rational use requires: (1) modification of the clozapine package insert worldwide to include lower doses for Asians and to avoid the lethality associated with pneumonia, (2) the use of clozapine levels for personalizing dosing, and (3) the use of slow and personalized titration. This may make clozapine as safe as possible and contribute to increased life expectancy and well-being. In the absence of data on COVID-19 in clozapine patients, clozapine possibly impairs immunological mechanisms and may increase pneumonia risk in infected patients. Psychiatrists should call their clozapine patients and families and explain to them that if the patient develops fever or flu-like symptoms, the psychiatrist should be called and should consider halving the clozapine dose. If the patient is hospitalized with pneumonia, the treating physician needs to assess for symptoms of clozapine intoxication since halving the dose may not be enough for all patients; consider decreasing it to one-third or even stopping it. Once the signs of inflammation and fever have disappeared, the clozapine dose can be slowly increased to the prior dosage level.
Topics: Antipsychotic Agents; Asian People; COVID-19; Clozapine; Coronavirus Infections; Drug Labeling; Humans; Pandemics; Pneumonia; Pneumonia, Viral; Psychiatry; Schizophrenia
PubMed: 32289791
DOI: 10.1159/000507638 -
Science (New York, N.Y.) Aug 2017The chemogenetic technology DREADD (designer receptors exclusively activated by designer drugs) is widely used for remote manipulation of neuronal activity in freely...
The chemogenetic technology DREADD (designer receptors exclusively activated by designer drugs) is widely used for remote manipulation of neuronal activity in freely moving animals. DREADD technology posits the use of "designer receptors," which are exclusively activated by the "designer drug" clozapine N-oxide (CNO). Nevertheless, the in vivo mechanism of action of CNO at DREADDs has never been confirmed. CNO does not enter the brain after systemic drug injections and shows low affinity for DREADDs. Clozapine, to which CNO rapidly converts in vivo, shows high DREADD affinity and potency. Upon systemic CNO injections, converted clozapine readily enters the brain and occupies central nervous system-expressed DREADDs, whereas systemic subthreshold clozapine injections induce preferential DREADD-mediated behaviors.
Topics: Animals; Binding, Competitive; Brain; Clozapine; Designer Drugs; Genetic Techniques; HEK293 Cells; Humans; Mice; Mice, Transgenic; Neurons; Receptor, Muscarinic M3; Receptor, Muscarinic M4
PubMed: 28774929
DOI: 10.1126/science.aan2475 -
CNS Drugs Jul 2022Treatment-resistant schizophrenia (TRS) will affect about one in three patients with schizophrenia. Clozapine is the only treatment approved for TRS, and patients should...
Treatment-resistant schizophrenia (TRS) will affect about one in three patients with schizophrenia. Clozapine is the only treatment approved for TRS, and patients should be treated as soon as possible to improve their chances of achieving remission. Despite its effectiveness, concern over side effects, monitoring requirements, and inexperience with prescribing often result in long delays that can expose patients to unnecessary risks and compromise their chances of achieving favorable long-term outcomes. We critically reviewed the literature on clozapine use in TRS, focusing on guidelines, systematic reviews, and algorithms to identify strategies for improving clozapine safety and tolerability. Based on this, we have provided an overview of strategies to support early initiation of clozapine in patients with TRS based on the latest evidence and our clinical experience, and have summarized the key elements in a practical, evidence-based checklist for identifying and managing patients with TRS, with the aim of increasing confidence in prescribing and monitoring clozapine therapy.
Topics: Antipsychotic Agents; Checklist; Clozapine; Humans; Schizophrenia; Schizophrenia, Treatment-Resistant
PubMed: 35759211
DOI: 10.1007/s40263-022-00932-2 -
Scientific Reports Mar 2019Muscarinic Designer Receptors Exclusively Activated by Designer Drugs (DREADD) gated by clozapine-N-oxide (CNO) allow selective G-protein cascade activation in...
Muscarinic Designer Receptors Exclusively Activated by Designer Drugs (DREADD) gated by clozapine-N-oxide (CNO) allow selective G-protein cascade activation in genetically specified cell-types in vivo. Here we compare the pharmacokinetics, off-target effects and efficacy of CNO, clozapine (CLZ) and compound 21 (Cmpd-21) at the inhibitory DREADD human Gi-coupled M4 muscarinic receptor (hM4Di). The half maximal effective concentration (EC) of CLZ was substantially lower (0.42 nM) than CNO (8.1 nM); Cmpd-21 was intermediate (2.95 nM). CNO was back-converted to CLZ in mice, and CLZ accumulated in brain tissue. However, CNO itself also entered the brain, and free cerebrospinal fluid (CSF) levels were within the range to activate hM4Di directly, while free (CSF) CLZ levels remained below the detection limit. Furthermore, directly injected CLZ was strongly converted to its pharmacologically active metabolite, norclozapine. Cmpd-21 showed a superior brain penetration and long-lasting presence. Although we identified a wide range of CNO and Cmpd-21 off-targets, there was hardly any nonspecific behavioural effects among the parameters assessed by the 5-choice-serial-reaction-time task. Our results suggest that CNO (3-5 mg/kg) and Cmpd-21 (0.4-1 mg/kg) are suitable DREADD agonists, effective at latest 15 min after intraperitoneal application, but both require between-subject controls for unspecific effects.
Topics: Animals; Cells, Cultured; Clozapine; Half-Life; Male; Mice; Mice, Inbred C57BL; Neurons; Piperazines; Rats; Rats, Sprague-Dawley
PubMed: 30872749
DOI: 10.1038/s41598-019-41088-2 -
JAMA Psychiatry May 2019The effectiveness of antipsychotic polypharmacy in schizophrenia relapse prevention is controversial, and use of multiple agents is generally believed to impair physical... (Comparative Study)
Comparative Study
IMPORTANCE
The effectiveness of antipsychotic polypharmacy in schizophrenia relapse prevention is controversial, and use of multiple agents is generally believed to impair physical well-being.
OBJECTIVE
To study the association of specific antipsychotic combinations with psychiatric rehospitalization.
DESIGN, SETTING, AND PARTICIPANTS
In this nationwide cohort study, the risk of psychiatric rehospitalization was used as a marker for relapse among 62 250 patients with schizophrenia during the use of 29 different antipsychotic monotherapy and polypharmacy types between January 1, 1996, and December 31, 2015, in a comprehensive, nationwide cohort in Finland. We conducted analysis of the data from April 24 to June 15, 2018. Rehospitalization risks were investigated by using within-individual analyses to minimize selection bias.
MAIN OUTCOMES AND MEASURES
Hazard ratio (HR) for psychiatric rehospitalization during use of polypharmacy vs during monotherapy within the same individual.
RESULTS
In the total cohort, including 62 250 patients, 31 257 individuals (50.2%) were men, and the median age was 45.6 (interquartile range, 34.6-57.9) years. The clozapine plus aripiprazole combination was associated with the lowest risk of psychiatric rehospitalization in the total cohort, being superior to clozapine, the monotherapy associated with the best outcomes, with a difference of 14% (HR, 0.86; 95% CI, 0.79-0.94) in the analysis including all polypharmacy periods, and 18% in the conservatively defined polypharmacy analysis excluding periods shorter than 90 days (HR, 0.82; 95% CI, 0.75-0.89; P < .001). Among patients with their first episode of schizophrenia, these differences between clozapine plus aripiprazole vs clozapine monotherapy were greater (difference, 22%; HR, 0.78; 95% CI, 0.63-0.96 in the analysis including all polypharmacy periods, and difference, 23%; HR, 0.77; 95% CI, 0.63-0.95 in the conservatively defined polypharmacy analysis). At the aggregate level, any antipsychotic polypharmacy was associated with a 7% to 13% lower risk of psychiatric rehospitalization compared with any monotherapy (ranging from HR, 0.87; 95% CI, 0.85-0.88, to HR, 0.93; 95% CI, 0.91-0.95; P < .001). Clozapine was the only monotherapy among the 10 best treatments. Results on all-cause and somatic hospitalization, mortality, and other sensitivity analyses were in line with the primary outcomes.
CONCLUSIONS AND RELEVANCE
Combining aripiprazole with clozapine was associated with the lowest risk of rehospitalization, indicating that certain types of polypharmacy may be feasible in the treatment of schizophrenia. Because add-on treatments are started when monotherapy is no longer sufficient to control for worsening of symptoms, it is likely that the effect sizes for polypharmacy are underestimates. Although the results do not indicate that all types of polypharmacy are beneficial, the current treatment guidelines should modify their categorical recommendations discouraging all antipsychotic polypharmacy in the maintenance treatment of schizophrenia.
Topics: Adult; Antipsychotic Agents; Aripiprazole; Clozapine; Drug Therapy, Combination; Female; Humans; Male; Middle Aged; Patient Readmission; Polypharmacy; Schizophrenia; Treatment Outcome
PubMed: 30785608
DOI: 10.1001/jamapsychiatry.2018.4320 -
Schizophrenia Research Mar 2016The primary aim of this systematic review and meta-analysis was to assess the proportion of patients with Treatment Resistant Schizophrenia (TRS) that respond to ECT... (Meta-Analysis)
Meta-Analysis Review
The primary aim of this systematic review and meta-analysis was to assess the proportion of patients with Treatment Resistant Schizophrenia (TRS) that respond to ECT augmentation of clozapine (C+ECT). We searched major electronic databases from 1980 to July 2015. We conducted a random effects meta-analysis reporting the proportion of responders to C+ECT in RCTs and open-label trials. Five clinical trials met our eligibility criteria, allowing us to pool data from 71 people with TRS who underwent C+ ECT across 4 open label trials (n=32) and 1 RCT (n=39). The overall pooled proportion of response to C+ECT was 54%, (95% CI: 21.8-83.6%) with some heterogeneity evident (I(2)=69%). With data from retrospective chart reviews, case series and case reports, 192 people treated with C+ECT were included. All studies together demonstrated an overall response to C+ECT of 66% (95% CI: 57.5-74.3%) (83 out of 126 patients responded to C+ECT). The mean number of ECT treatments used to augment clozapine was 11.3. 32% of cases (20 out of 62 patients) with follow up data (range of follow up: 3-468weeks) relapsed following cessation of ECT. Adverse events were reported in 14% of identified cases (24 out of 166 patients). There is a paucity of controlled studies in the literature, with only one single blinded randomised controlled study located, and the predominance of open label trials used in the meta-analysis is a limitation. The data suggests that ECT may be an effective and safe clozapine augmentation strategy in TRS. A higher number of ECT treatments may be required than is standard for other clinical indications. Further research is needed before ECT can be included in standard TRS treatment algorithms.
Topics: Antipsychotic Agents; Clozapine; Electroconvulsive Therapy; Humans; Schizophrenia
PubMed: 26827129
DOI: 10.1016/j.schres.2016.01.024 -
Schizophrenia Bulletin Dec 2020Evidence for the management of inadequate clinical response to clozapine in treatment-resistant schizophrenia is sparse. Accordingly, an international initiative was...
Clozapine Combination and Augmentation Strategies in Patients With Schizophrenia -Recommendations From an International Expert Survey Among the Treatment Response and Resistance in Psychosis (TRRIP) Working Group.
BACKGROUND
Evidence for the management of inadequate clinical response to clozapine in treatment-resistant schizophrenia is sparse. Accordingly, an international initiative was undertaken with the aim of developing consensus recommendations for treatment strategies for clozapine-refractory patients with schizophrenia.
METHODS
We conducted an online survey among members of the Treatment Response and Resistance in Psychosis (TRRIP) working group. An agreement threshold of ≥75% (responses "agree" + "strongly agree") was set to define a first-round consensus. Questions achieving agreement or disagreement proportions of >50% in the first round, were re-presented to develop second-round final consensus recommendations.
RESULTS
Forty-four (first round) and 49 (second round) of 63 TRRIP members participated. Expert recommendations at ≥75% agreement included raising clozapine plasma levels to ≥350 ng/ml for refractory positive, negative, and mixed symptoms. Where plasma level-guided dose escalation was ineffective for persistent positive symptoms, waiting for a delayed response was recommended. For clozapine-refractory positive symptoms, combination with a second antipsychotic (amisulpride and oral aripiprazole) and augmentation with ECT achieved consensus. For negative symptoms, waiting for a delayed response was recommended, and as an intervention for clozapine-refractory negative symptoms, clozapine augmentation with an antidepressant reached consensus. For clozapine-refractory suicidality, augmentation with antidepressants or mood-stabilizers, and ECT met consensus criteria. For clozapine-refractory aggression, augmentation with a mood-stabilizer or antipsychotic medication achieved consensus. Generally, cognitive-behavioral therapy and psychosocial interventions reached consensus.
CONCLUSIONS
Given the limited evidence from randomized trials of treatment strategies for clozapine-resistant schizophrenia (CRS), this consensus-based series of recommendations provides a framework for decision making to manage this challenging clinical situation.
Topics: Adult; Antipsychotic Agents; Clozapine; Drug Synergism; Drug Therapy, Combination; Humans; Outcome Assessment, Health Care; Practice Guidelines as Topic; Schizophrenia
PubMed: 32421188
DOI: 10.1093/schbul/sbaa060