Sublingual Atropine Administration for Clozapine-Induced Sialorrhea in Bipolar Disorder: A Case Report Highlighting its Efficacy, Safety Concerns and Challenges.

We discuss a case with off-label sublingual administration of atropine for clozapine-induced sialorrhea (CIS) after failure of two commonly used agents to manage CIS. Atropine had a demonstrable efficacy, as measured by means of sialometry conducted before and after its administration. The salivary rate, initially measured at 0.60 g/min one hour before atropine administration, reduced to 0.23 g/min two hours after administration. Sublingual administration of atropine was found to be an efficacious option for this patient, but safety issues particularly tachycardia and pragmatics such as risk of inadvertent overdose led to its discontinuation after the initial dose. Developing micro-dosing devices for sublingual atropine could enhance administration precision, reduce side effects, and provide a cost-effective solution. The case report also underscores the need to employ sialometry for the objective assessment of treatment outcomes in future research trials for hypersalivation.

Effective and safe use of intramuscular clozapine in a patient presenting with catatonia and thrombocytopenia.

Clozapine is the most effective medication for the management of treatment-resistant schizophrenia and schizoaffective disorder, and its discontinuation can pose significant challenges in treatment. We present a patient with a diagnosis of schizoaffective disorder who was stable on clozapine for a decade until discontinuation due to thrombocytopenia. She experienced a relapse of her illness, presenting with psychotic and catatonic features with poor oral intake and physical health complications requiring a lengthy admission to the hospital. There was a poor response to alternative antipsychotics and a full course of electroconvulsive therapy. Intramuscular (IM) clozapine was initiated due to catatonia and refusal to accept oral medications. After receiving 10 doses of IM clozapine, she started accepting oral clozapine and made a full recovery within a few weeks. The low platelet count was persistent, and a bone marrow biopsy showed results consistent with immune thrombocytopenia being the cause of that low platelet count.

Evaluating the impact of COVID-19 on medication adherence and health care utilization among individuals with psychotic disorders who are prescribed long-acting injectables (LAIs) or clozapine: A population-based study in Manitoba, Canada.

BACKGROUND: Ongoing psychiatric follow-up and medication adherence improve outcomes for patients with psychotic disorders. Due to COVID-19, outpatient care may have been disrupted, impacting healthcare utilization. METHODS: A retrospective population-wide study was conducted for adults in Manitoba, Canada. Medication adherence and healthcare utilization were examined from 2019 to 2021. The presence of a diagnosed psychotic disorder was identified in the five years before the index date in each year. The LAI and clozapine cohorts consisted of those who received at least two prescriptions in each year 180 days before the March 20th index date. The change in adherence was measured using the average Medication Possession Ratio. Healthcare utilization rates were compared using Generalized Estimating Equation models. RESULTS: There were no significant differences between LAI and clozapine discontinuation rates before and during the pandemic. In the LAI cohort, general practitioner visits decreased significantly (-3.5 %, p = 0.039) across four quarters of 2021 versus 2019. All-cause hospitalizations decreased by 16.8 % in 2020 versus 2019 (p = 0.0055), while psychiatric hospitalizations decreased by 18.7 % across four quarters in 2020 (p = 0.0052) and 13.7 % in 2021 (p = 0.0425), versus 2019 in the LAI cohort. There was a significant transition to virtual care during the first wave of COVID-19 (71 % in clozapine, 51 % in LAI cohorts). Trends in total outpatient visits and non-psychiatric hospitalizations remained stable. CONCLUSION: COVID-19 had no substantial impact on LAI and clozapine discontinuation rates for patients previously adherent. Outpatient care remained stable, with a significant proportion of visits being done virtually at the outset of the pandemic.

Plasma Clozapine and N -Desmethylclozapine (Norclozapine) Concentrations and the Clozapine/Norclozapine Ratio : Effect of Dose, Sex, and Cigarette Smoking.

BACKGROUND: Smoking enhances plasma clozapine clearance, but the magnitude of the effect across the dose and age ranges is unclear. METHODS: We audited clozapine dose and predose plasma clozapine and N -desmethylclozapine (norclozapine) concentrations by sex and smoking habit in samples submitted for clozapine TDM, 1996-2017. RESULTS: There were 105,316/60,792 and 34,288/31,309 samples from male/female smokers/nonsmokers, respectively. There were distinct dose-median plasma concentration trajectories for male/female smokers/nonsmokers across the range <50 to >850 mg d -1 . For both sexes, the percentage difference in median plasma clozapine in nonsmokers versus smokers averaged 50% but was greatest for men (76%) and women (59%) in the 151 to 250 mg d -1 dose band. In men, the percentage difference declined steadily to 34% at doses of ≥850 mg d -1 . In women, the difference after falling initially remained relatively constant at 40% to 54%. The pattern in median plasma clozapine/norclozapine ratio by plasma clozapine concentration and dose groups was independent of sex and smoking habit, but increased with plasma clozapine concentration (higher ratio at higher concentrations) and also changed with dose. Median plasma clozapine concentration and median clozapine dose by sex and smoking habit were similar up to age 60 years. Proportional weight gain was similar over time in smokers and nonsmokers of either sex. IMPLICATIONS: These data explain the variations in the effect size of starting or stopping smoking on plasma clozapine concentration at constant dose reported in different studies. Changes in smoking habit in patients prescribed clozapine require prompt dose adjustment.

Association of new-onset diabetes mellitus in adults with schizophrenia treated with clozapine versus patients treated with olanzapine, risperidone, or quetiapine: A systematic review and meta-analysis.

INTRODUCTION: Many articles suggest that clozapine was strongly associated with a higher incidence of new-onset diabetes mellitus, and the issue has remained unsettled. Many articles have compared clozapine with FGAs, but few have compared clozapine with SGAs. We aimed to compare the risk of new-onset diabetes mellitus in adults with schizophrenia treated with clozapine and other SGAs. METHODS: We conducted a comprehensive search of databases from their inception up until August 26, 2023. The specific databases include PubMed, Embase and others. We included non-randomized controlled trials involving the use of SGAs such as clozapine, olanzapine, risperidone, quetiapine, amisulpride, and zotepine, with a focus on new-onset diabetes mellitus as an outcome. We utilized odds ratio with 95 % credible intervals (95 % CI) as our effect size measures. The study protocol is registered with PROSPERO, number CRD42024511280. RESULTS: We included 7 studies with sufficient data to include in the meta-analysis. A total of eight studies with 641,48 participants met the eligibility criteria. The OR of the incidence rates of new-onset diabetes between clozapine and olanzapine was 0.95 (95 % CI:[0.82-1.09]), between clozapine and risperidone was 1.25 (95 % CI: [1.09-1.44]), between clozapine and quetiapine was 1.44 (95 % CI: [0.92-2.25]). CONCLUSION: In patients with schizophrenia, clozapine has been found to have a higher rate of new-onset diabetes mellitus compared to risperidone. However, there was no significant difference in incidence rate between clozapine versus olanzapine and quetiapine. These findings can assist clinicians in balancing the risks and benefits of those drugs.

Long-term metabolic side effects of second-generation antipsychotics in Chinese patients with schizophrenia: A within-subject approach with modelling of dosage effects.

BACKGROUND: Second-generation antipsychotics (SGAs) are commonly used to treat schizophrenia (SCZ), but SGAs may differ in the severity of side effects. Long-term studies are lacking, and previous observational studies have limitations, such as failure to account for confounding factors and short follow-up durations. AIMS: To compare the long-term anthropometric and metabolic side effects of seven SGAs in a Chinese population, using a within-subject approach to reduce the risk of confounding. METHOD: We collected longitudinal data of SGA prescriptions, concomitant medications, fasting blood glucose (BG), lipid profiles, and BMI in a cohort of 767 patients with SCZ, with follow-up lasting up to 18.7 years (median ∼6.2 years). A total of 192,152 prescription records were retrieved, with 27,723 metabolic measures analysed. Linear mixed models were used to estimate the effects of SGA on BG, lipid profiles and BMI. Besides studying the effects of SGA medications (as binary predictors), we also investigated the effects of SGA dosage on metabolic profiles. RESULTS: Considering SGA medications as binary predictors, clozapine and olanzapine were associated with the most substantial worsening of lipid profiles and BMI. A significant increase in BG was observed with clozapine only. Amisulpride, paliperidone and quetiapine were associated with worsened lipid profiles and increased BMI. Conversely, aripiprazole was associated with significant improvement in lipid profiles but a small increase in BMI. When SGA dosage was considered, the model showed consistent results overall. At the minimum effective dose, clozapine was associated with the most severe metabolic side effects, followed by olanzapine. Risperidone and aripiprazole showed the least metabolic side effects, with aripiprazole being significantly associated with lower lipids. CONCLUSIONS: This study clarified the long-term and dose-dependent effects of different SGAs on anthropometric and metabolic parameters in Chinese SCZ patients. Our findings may inform clinicians and SCZ patients of SGA choices.

Outpatient prescription of clozapine in Colombia: factors related to the use of doses lower than 100 mg/day / Prescripción ambulatoria de clozapina en Colombia: factores relacionados con el uso de dosis inferiores a 100 mg/día.

Although commonly used in clinical practice, scientific literature about clozapine prescription patterns in Colombia is scarce. A cross-sectional observational study was conducted in an outpatient clinic in Bogotá, Colombia. Between 2016 and 2018, clozapine was prescribed to 2603 patients, mainly for Schizophrenia Spectrum Disorders and Bipolar and Depressive Disorders, at a median dose of 100mg/day. After controlling for other variables, older age was the only variable that explained the use of doses lower than 100mg/day. Clozapine was not only used for Treatment-Resistant Schizophrenia, and further studies are needed to explain these differences.

Aunque se utiliza comúnmente en la práctica clínica, la literatura científica sobre los patrones de prescripción de clozapina en Colombia es escasa. Se realizó un estudio observacional transversal en el servicio ambulatorio de una clínica de referencia en Bogotá, Colombia. Entre 2016 y 2018, se recetó clozapina a 2603 pacientes, principalmente para esquizofrenia y trastornos relacionados, trastorno afectivo bipolar y trastornos depresivos, a una dosis media de 100 mg/día. Después de controlar otras variables, la edad avanzada fue la única variable que explicó el uso de dosis inferiores a 100 mg/día. La clozapina no se utilizó sólo para la esquizofrenia resistente al tratamiento, y se necesitan estudios adicionales para explicar estas diferencias.

Use of Clozapine in persons with a history of seizures: A retrospective study.

BACKGROUND: Seizures are considered to be one of the dreaded side effects of clozapine, and due to this, the use of clozapine is avoided in patients with treatment-resistant schizophrenia. Resultantly, there is little information about the use of clozapine among patients with seizure disorder. AIM: To assess the safety of clozapine in patients with history of seizures in their lifetime before starting clozapine and receiving clozapine for the management of psychotic disorders. RESULTS: Out of the 958 patients, 35 (3.65 %) had a history of at least one seizure episode before starting clozapine, with a mean of 5.06 (SD: 7.23; Median: 3.00) seizures before starting clozapine. The mean duration between the last seizure and the starting of clozapine was 123.75 (SD: 124.99; Median: 84) months, with nine patients having an episode of seizure in the previous 12 months and 15 patients being seizure-free for more than ten years. About one-fourth (25.7 %; nine out of 35) of the patients had recurrence of seizure while receiving clozapine for a mean duration of about five years. When the recurrence of seizure after starting clozapine was evaluated in patients receiving antiepileptics along with clozapine, the incidence of at least one seizure was 26.67 % (4 out of 15), and among those not receiving antiepileptics, the incidence of at least one seizure was 25 % (5 out of 20). The dose of clozapine at which seizure was noted ranged from 12.5 mg to 600 mg/day with a mean of 236.25 (SD: 169.04; Median: 162.5) mg/day. In none of the patients, clozapine had to be stopped due to the continuation of seizures. CONCLUSION: About one-fourth of the patients with history of an episode of seizure have recurrence of seizure while receiving clozapine. The demographic and clinical variables do not differ between those who develop and who do not develop seizures after starting clozapine, including concomitant use of antiepileptics.

An experience of using Clozapine in elderly patients with mental disorders.

BACKGROUND: There is little information on using clozapine in elderly patients with mental disorders from India. AIM: To evaluate the sociodemographic and clinical profile of elderly (age ≥ 60 years) patients started on clozapine. METHODOLOGY: The clozapine registry in the department was screened to identify elderly patients who were started on clozapine. Treatment records of these patients were reviewed to extract sociodemographic and clinical details. RESULTS: Out of the available information of 1058 patients in the registry, 42 (3.96 %) were elderly (≥ 60 years) patients. About two-thirds of the patients had treatment resistance, i.e., their psychotic illness had not responded to two adequate trials of antipsychotics, and the second most common indication for starting clozapine was tardive dystonia or tardive dyskinesia (23.8 %). The mean dose of clozapine was 135.89 (SD: 109.6; Range: 37.5-500; median: 87.5) mg/day. The mean duration of clozapine use at the time of data extraction for the study sample was 3.55 (SD: 2.15; Range 0.3-9; median: 3) years. At the last follow-up, about three-fourths of patients were experiencing at least one side effect, with constipation being the most common side effect, followed by sedation, weight gain, and hypersalivation. In only four patients, clozapine was stopped during the follow-up. In terms of effectiveness, majority of the patients were rated as much improved or very much improved on Clinical Global Impression-Improvement subscale. CONCLUSION: Clozapine can be safely used in elderly patients with mental disorders. Hence, clozapine should not be withheld in elderly patients with mental disorders whenever indicated.

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.

Investigating in VigiBase over 6000 cases of pneumonia in clozapine-treated patients in the context of the literature: focus on high lethality and the association with aspiration pneumonia.

BACKGROUND: The literature associates clozapine with pneumonia/aspiration pneumonia. RESEARCH DESIGN AND METHODS: The international pharmacovigilance database (VigiBase™) uses the information component (IC) as statistical signal. VigiBase clozapine reports were analyzed for pneumonia/aspiration pneumonia from introduction to 10 May 2023. RESULTS: There were 6392 cases of all types of pneumonia (5572 cases of pneumonia, 775 of aspiration pneumonia, and 45 combined). The IC was 3.52 for aspiration pneumonia, introduced as a VigiBase label in 2003, and 1.91 for pneumonia. Patients were reclassified as 3628 with no signs of aspiration and 1533 with signs. Signs of aspiration were strongly associated with some co-medications: olanzapine, odds ratio (OR) = 23.8, 95% confidence interval (CI), 14.9-38.0; risperidone OR = 18.6, CI, 11.4-30.4; valproic acid, OR = 5.5, CI, 4.5-6.6; and benzodiazepines OR = 5.5, CI, 4.5-6.6. In 2415 cases with completed data, fatal outcomes made up 45% (signs of aspiration made no difference), but there was wide variability from 0% (females <45 years of age; duration ≤30 days) to 76% (males >64 years of age; duration >1 year). During the first week, pneumonia was associated with 1) very high titration doses, 2) very small doses in Parkinson's disease, and 3) Japan vs other countries. CONCLUSIONS: In clozapine-treated patients: 1) at least 30% of pneumonia cases may be aspiration pneumonia, 2) stopping some co-medications may decrease the risk of aspiration pneumonia, 3) average lethality in pneumonia was 45% but may be around 75% in geriatric patients with long-term treatment, and 4) safer titrations may sometimes require 5-mg tablets.

Semi-physiological Pharmacokinetic Model of Clozapine and Norclozapine in Healthy, Non-smoking Volunteers: The Impact of Race and Genetics.

BACKGROUND AND OBJECTIVES: Clozapine is the medication of choice for treatment-resistant schizophrenia. However, it has a complex metabolism and unexplained interindividual variability. The current work aims to develop a pharmacokinetic model of clozapine and norclozapine in non-smokers and assess the impact of demographic and genetic predictors. METHODS: Healthy volunteers were recruited in a population pharmacokinetic study. Blood samples were collected at 30 min and 1, 2, 3, 5 and 8 h following a single flat dose of clozapine (12.5 mg). The clozapine and norclozapine concentrations were measured via high-performance liquid chromatography-ultraviolet method. A semi-physiological pharmacokinetic model of clozapine and norclozapine was developed using nonlinear mixed-effects modeling. Clinical and genetic predictors were evaluated, including CYP1A2 (rs762551) and ABCB1 (rs2032582), using restriction fragment length polymorphism. RESULTS: A total of 270 samples were collected from 33 participants. The data were best described using a two-compartment model for clozapine and a two-compartment model for norclozapine with first-order absorption and elimination and pre-systemic metabolism. The estimated (relative standard error) clearance of clozapine and norclozapine were 27 L h-1 (31.5 %) and 19.6 L h-1 (30%), respectively. Clozapine clearance was lower in sub-Saharan Africans (n = 4) and higher in Caucasians (n = 9) than Asians (n = 20). Participants with CYP1A2 (rs762551) (n = 18) and ABCB1 (rs2032582) (n = 12) mutant alleles had lower clozapine clearance in the univariate analysis. CONCLUSIONS: This is the first study to develop a semi-physiological pharmacokinetic model of clozapine and norclozapine accounting for the pre-systemic metabolism. Asians required lower doses of clozapine as compared with Caucasians, while clozapine pharmacokinetics in sub-Saharan Africans should be further investigated in larger trials.

Overcoming clozapine's adverse events: a narrative review of systematic reviews and meta-analyses.

INTRODUCTION: Clozapine is the gold standard treatment for treatment-resistant schizophrenia, however adverse events remain a clinical challenge. AREAS COVERED: This review presents a narrative synthesis of systematic reviews and meta-analyses that have reported the onset, incidence, prevalence, and management of clozapine's adverse events. We conducted a systematic literature search using PubMed, Embase, PsycINFO, OvidMEDLINE, CINAHL, and the Cochrane Database of Systematic Reviews from inception to April 2024. EXPERT OPINION: Effective management of clozapine's adverse events necessitates multi-faceted, individualized, and shared-decision strategies. Despite a lack of high-quality systematic evidence, expert inter-disciplinary solutions are provided to help address a critical need for clinical guidance. This 35-year update offers an evidence-based framework to assist clinicians, patients, and caregivers navigate the adverse events associated with clozapine therapy.

Clozapine is an important medication for people with schizophrenia who do not respond to other treatments. It has been used for over 30 years and provides relief from symptoms and improves quality of life. However, it has side effects that can be daunting for both healthcare workers and people taking clozapine. This article summarizes the latest research on clozapine's side effects into an easy-to-use guide to help understand the side effects better. With the right knowledge and a team approach involving healthcare workers, patients, their families and carers, the risks of clozapine's side effects can be managed. Proactive and careful monitoring for side effects, education on what to do if they occur, open conversations, and regular health checkups can significantly reduce the risk that side effects become a problem.

Beneficial Effects of Concomitant Long-Acting Injectable Antipsychotics on Time to Rehospitalization in Patients With Treatment-Resistant Schizophrenia Receiving Clozapine: A Retrospective Cohort Study.

Introduction: This study aimed to assess the association between long-acting injectable (LAI) antipsychotic prescription and the risk of psychiatric hospitalization in patients with treatment-resistant schizophrenia (TRS) receiving clozapine.Methods: In this retrospective cohort study at a single tertiary psychiatric center, we analyzed rehospitalization hazard ratios (HRs) in refractory schizophrenia patients, classified by DSM-IV-TR and DSM-5 criteria. We examined various psychotropic regimens-clozapine with or without other oral antipsychotics (OAPs) or LAI antipsychotics. Subgroups were stratified by daily clozapine dosage and previous admissions.Results: A total of 719 patients were included in the study. Analyses were conducted on all the patients over 3- month, 6-month, and 1-year periods. Patients treated with a combination of clozapine and LAI antipsychotics (CLO + LAI) had a significantly higher number of previous hospitalizations (P = .003), and a higher daily dose of clozapine (P < .001) was found in the CLO + OAP group than in the CLO (monotherapy) group and the CLO + LAI group. Patients treated with LAI antipsychotic comedication had significantly lower HRs for rehospitalization in 1 year among 3 studied groups. Moreover, the protective effects of LAI antipsychotics were observed in all the subgroups stratified by daily clozapine dosage and number of previous admissions to represent disease severity.Conclusion: The combination of clozapine and LAI antipsychotics was associated with a significantly lower risk of rehospitalization compared to both the combination of clozapine and OAPs and clozapine monotherapy. The use of LAI antipsychotics should be considered to prevent rehospitalization in patients with TRS who are already being treated with clozapine.

Optimizing co-prescription of clozapine and antiseizure medications: a systematic review and expert recommendations for clinical practice.

INTRODUCTION: Antiseizure medication (ASM) add-on to clozapine may be efficient to target clozapine-resistant mood or psychotic symptoms or clozapine-related adverse drug reactions (ADR) such as seizures. We aimed to synthesize the information relevant for clinical practice on the risks and benefits of clozapine-ASM co-prescription. AREAS COVERED: Articles were identified with MEDLINE, Web of Sciences and PsycINFO search from inception through October 2023. The review was restricted to ASM with mood-stabilizing properties or with potential efficacy for resistant psychotic symptoms (valproate (VPA), lamotrigine, topiramate, carbamazepine, oxcarbazepine). EXPERT OPINION: VPA add-on to clozapine is associated with a high risk of serious ADR (myocarditis, neutropenia, pneumonia) mostly explained by complex time-dependent drug-drug interactions. The initial inhibitory effects on clozapine metabolism require slow titration to avoid immuno-allergic reactions. After the titration period, VPA has mainly inductive effects on clozapine metabolism that are more marked in smokers requiring therapeutic drug monitoring. Lamotrigine and topiramate add-on may be recommended as the first-line treatment for clozapine-related seizures, but there is limited evidence regarding the efficacy of this strategy for clozapine-resistant psychotic symptoms. Carbamazepine should not be co-prescribed with clozapine because of its potential for agranulocytosis and for inducing clozapine metabolism.

Continuous oral olanzapine or clozapine treatment initiated in adolescence has differential short- and long-term impacts on antipsychotic sensitivity than those initiated in adulthood.

One of the major discoveries in recent research on antipsychotic drugs is that antipsychotic treatment in adolescence could induce robust long-term alterations in antipsychotic sensitivity that persist into adulthood. These long-term impacts are likely influenced by various factors, including the "diseased" state of animals, sex, type of drugs, mode of drug administration, and age of treatment onset. In this study we compared the short- and long-term behavioral effects of 21-day continuous oral olanzapine (7.5 mg/kg/day) or clozapine (30.0 mg/kg/day) administration in heathy or maternal immune activated adolescent (33-53 days old) or adult (80-100 days old) rats of both sexes. We used a conditioned avoidance response model to assess the drug-induced alterations in antipsychotic sensitivity. Here, we report that while under the chronic drug treatment period, olanzapine progressively increased its suppression of avoidance responding over time, especially when treatment was initiated in adulthood. Clozapine's suppression depended on the age of drug exposure, with treatment initiated in adulthood showing a suppression while that initiated in adolescent did not. After a 17-day drug-free interval, in a drug challenge test, olanzapine treatment initiated in adolescence caused a decrease in drug sensitivity, as reflected by less avoidance suppression (a tolerance effect); whereas that initiated in adulthood appeared to cause an increase (more avoidance suppression, a sensitization effect). Clozapine treatments initiated in both adolescence and adulthood caused a similar tolerance effect. Our findings indicate that the same chronic antipsychotic treatment regimen initiated in adolescence or adulthood can have differential short- and long-term impacts on drug sensitivity.

Differential impact of intermittent versus continuous treatment with clozapine on fatty acid metabolism in the brain of an MK-801-induced mouse model of schizophrenia.

Continuous antipsychotic treatment is often recommended to prevent relapse in schizophrenia. However, the efficacy of antipsychotic treatment appears to diminish in patients with relapsed schizophrenia and the underlying mechanisms are still unknown. Moreover, though the findings are inconclusive, several recent studies suggest that intermittent versus continuous treatment may not significantly differ in recurrence risk and therapeutic efficacy but potentially reduce the drug dose and side effects. Notably, disturbances in fatty acid (FA) metabolism are linked to the onset/relapse of schizophrenia, and patients with multi-episode schizophrenia have been reported to have reduced FA biosynthesis. We thus utilized an MK-801-induced animal model of schizophrenia to evaluate whether two treatment strategies of clozapine would affect drug response and FA metabolism differently in the brain. Schizophrenia-related behaviors were assessed through open field test (OFT) and prepulse inhibition (PPI) test, and FA profiles of prefrontal cortex (PFC) and hippocampus were analyzed by gas chromatography-mass spectrometry. Additionally, we measured gene expression levels of enzymes involved in FA synthesis. Both intermittent and continuous clozapine treatment reversed hypermotion and deficits in PPI in mice. Continuous treatment decreased total polyunsaturated fatty acids (PUFAs), saturated fatty acids (SFAs) and FAs in the PFC, whereas the intermittent administration increased n-6 PUFAs, SFAs and FAs compared to continuous administration. Meanwhile, continuous treatment reduced the expression of Fads1 and Elovl2, while intermittent treatment significantly upregulated them. This study discloses the novel findings that there was no significant difference in clozapine efficacy between continuous and intermittent administration, but intermittent treatment showed certain protective effects on phospholipid metabolism in the PFC.

Clearing the Fog: A Review of Antipsychotics for Parkinson's-Related Hallucinations: A Focus on Pimavanserin, Quetiapine and Clozapine.

Parkinson's disease is a progressive neurodegenerative disorder characterized by motor and non-motor symptoms, including hallucinations. The use of antipsychotic medications is a common strategy to manage hallucinations associated with Parkinson's disease psychosis (PDP). However, careful consideration is necessary when selecting the most appropriate drug due to the potential risks associated with the available treatment options. Atypical antipsychotics (AAPs), such as Pimavanserin and Clozapine, have effectively controlled PDP symptoms. On the contrary, the support for utilizing quetiapine is not as substantial as other antipsychotics because research studies specifically investigating its application are still emerging and relatively recent. The broad mechanisms of action of AAPs, involving dopamine and serotonin receptors, provide improved outcomes and fewer side effects than typical antipsychotics. Conversely, other antipsychotics, including risperidone, olanzapine, aripiprazole, ziprasidone, and lurasidone, have been found to worsen motor symptoms and are generally not recommended for PDP. While AAPs offer favorable benefits, they are associated with specific adverse effects. Extrapyramidal symptoms, somnolence, hypotension, constipation, and cognitive impairment are commonly observed with AAP use. Clozapine, in particular, carries a risk of agranulocytosis, necessitating close monitoring of blood counts. Pimavanserin, a selective serotonin inverse agonist, avoids receptor-related side effects but has been linked to corrected QT (QTc) interval prolongation, while quetiapine has been reported to be associated with an increased risk of mortality. This review aims to analyze the benefits, risks, and mechanisms of action of antipsychotic medications to assist clinicians in making informed decisions and enhance patient care.