Search results for "clozapine"
showing 10 items of 42 documents
Structural Covariance of Cortical Gyrification at Illness Onset in Treatment Resistance: A Longitudinal Study of First-Episode Psychoses
2021
AbstractTreatment resistance (TR) in patients with first-episode psychosis (FEP) is a major cause of disability and functional impairment, yet mechanisms underlying this severe disorder are poorly understood. As one view is that TR has neurodevelopmental roots, we investigated whether its emergence relates to disruptions in synchronized cortical maturation quantified using gyrification-based connectomes. Seventy patients with FEP evaluated at their first presentation to psychiatric services were followed up using clinical records for 4 years; of these, 17 (24.3%) met the definition of TR and 53 (75.7%) remained non-TR at 4 years. Structural MRI images were obtained within 5 weeks from first…
Pharmacokinetic Interactions of Clozapine With Selective Serotonin Reuptake Inhibitors
1998
Pharmacokinetic interactions of clozapine and its metabolites N-desmethylclozapine and clozapine N-oxide with the selective serotonin reuptake inhibitors (SSRIs) fluvoxamine and paroxetine were investigated in a prospective study in schizophrenic patients under steady-state conditions. Thirty patients were treated with clozapine at a target dose of 2.5 to 3.0 mg/kg of body weight. After gradual dose escalation, serum concentrations of clozapine and two metabolites were determined twice at 7-day intervals after steady-state conditions had been reached. Then, fluvoxamine (50 mg/day) or paroxetine (20 mg/day) was added in 16 and 14 patients, respectively. Serum concentrations of clozapine and …
Addition of Low-Dose Fluvoxamine to Low-Dose Clozapine Monotherapy in Schizophrenia: Drug Monitoring and Tolerability Data from a Prospective Clinica…
1999
Combining fluvoxamine and clozapine may be a strategy to improve therapeutic effects on negative symptoms in schizophrenic patients. Fluvoxamine, however, markedly inhibits the metabolism of clozapine, and hazardous side effects may result. This study prospectively investigated the safety and tolerability of an add-on therapy with fluvoxamine to a clozapine monotherapy in schizophrenic patients. Sixteen schizophrenic patients received 50 mg fluvoxamine as a comedication after having reached steady-state conditions under clozapine monotherapy. Patients were monitored for subjective adverse events, laboratory parameters, EEG and ECG recordings, orthostatic hypotension and their psychopatholog…
Body mass index as a determinant of clozapine plasma concentrations: A pharmacokinetic-based hypothesis
2021
Background: Knowledge regarding the impact of body composition measures on pharmacokinetics of antipsychotics is limited. Aims: Our aim was to investigate the impact of body weight and body mass index on clozapine pharmacokinetics using a therapeutic drug monitoring database. Methods: A large therapeutic drug monitoring dataset of clozapine plasma concentrations considering three patient subgroups was analysed: a control group (CLZ0, 20–30 kg/m2, n=266), a group with high body mass index (CLZhigh, body mass index ⩾30 kg/m2, n=162) and with low body mass index values (CLZlow, body mass index <20 kg/m2, n=27). Comparisons of plasma and dose-adjusted plasma concentrations (C/D) of clozapine…
Dopamine D2/3 receptor occupancy by quetiapine in striatal and extrastriatal areas
2010
Quetiapine is next to clozapine an antipsychotic agent that exerts hardly any extrapyramidal side-effects at clinical efficacious doses. Some previous receptor occupancy studies reported preferential extrastriatal D2/3 receptor (D2/3R)-binding properties of second-generation antipsychotics and suggested this as possible reason for improved tolerability. This positron emission tomography (PET) investigation was designed to compare the occupancy of dopamine D2/3Rs by quetiapine in striatal and extrastriatal brain regions. Therefore, a cohort of 16 quetiapine-treated psychotic patients underwent an [18F]fallypride (FP) PET scan. Due to the high affinity of FP and its comparatively long half-li…
Reduced oxytocin receptor gene expression and binding sites in different brain regions in schizophrenia: A post-mortem study
2016
Schizophrenia is a severe neuropsychiatric disorder with impairments in social cognition. Several brain regions have been implicated in social cognition, including the nucleus caudatus, prefrontal and temporal cortex, and cerebellum. Oxytocin is a critical modulator of social cognition and the formation and maintenance of social relationships and was shown to improve symptoms and social cognition in schizophrenia patients. However, it is unknown whether the oxytocin receptor is altered in the brain. Therefore, we used qRT-PCR and Ornithine Vasotocin Analog ([125I]OVTA)-based receptor autoradiography to investigate oxytocin receptor expression at both the mRNA and protein level in the left p…
Automated Determination of Ziprasidone by HPLC With Column Switching and Spectrophotometric Detection
2005
An isocratic high-performance liquid chromatography (HPLC) method with column switching and ultraviolet (UV) detection is described for quantitative analysis of the new antipsychotic drug ziprasidone. After centrifugation of serum or plasma samples and addition of fluperlapine as internal standard, the samples were injected into the HPLC system. On-line sample clean-up was conducted on a column (10 x 4.0 mm ID) filled with silica C8 material (20-microm particle size) using 8% (vol/vol) acetonitrile in deionized water as eluent. Ziprasidone was eluted and separated on ODS Hypersil C18 material (5 microm; column size 250 x 4.6 mm ID) using acetonitrile-water-tetramethylethylendiamine (50:49.6…
[123I]IBZM SPECT in patients treated with typical and atypical neuroleptics: relationship to drug plasma levels and extrapyramidal side effects
1997
[123I]Iodobenzamide (IBZM) is an iodine-labeled dopamine receptor ligand and can be used to visualize brain D2 receptors in humans with single photon emission computerized tomography (SPECT). The ratio of striatal IBZM uptake to uptake in frontal cortex (ST/FC ratio) represents a semiquantitative measure of D2 receptor binding in the striatum. Our study sample included six patients treated with haloperidol (3.0-8.0 mg/day orally; one patient with an average of 0.9 mg/day intramuscularly), five patients with benperidol (9.0-15.0 mg/day orally) and nine patients treated with clozapine (200.0-600.0 mg/day orally). Typical neuroleptics (TNs) and atypical neuroleptics (ANs) were significantly di…
Combination treatment with clozapine and paroxetine in schizophrenia: safety and tolerability data from a prospective open clinical trial.
1998
Clozapine is a drug with many side effects, some of them with potentially hazardous outcome (e.g. seizures, agranulocytosis), if not carefully monitored. It has been shown that the metabolism of clozapine may be affected by concomitant treatment with selective serotonin reuptake inhibitors (SSRIs), while there have been reports of improved efficacy on negative symptomatology of clozapine in combination with SSRIs. Therefore, this prospective open clinical trial was performed to investigate the safety and tolerability of the coadministration of clozapine and paroxetine under control of serum concentrations of clozapine and its metabolites and the effect of this combination treatment on psych…
The striatal and extrastriatal D2/D3 receptor-binding profile of clozapine in patients with schizophrenia.
2005
Positron emission tomography (PET) studies reveal that clozapine at clinically used doses occupies less than 60% of D2/D3 dopamine receptors in human striatum. Here, the occupancy of D2/D3 dopamine receptors by clozapine in patients with schizophrenia was determined to test the hypothesis that clozapine binds preferentially to extrastriatal dopamine receptors. A total of 15 clozapine-treated inpatients with schizophrenia underwent a [18F]fallypride PET scan. Receptor occupancy was calculated as percent reduction in binding potential relative to unblocked values measured in seven normal volunteers. Mean D2/D3 receptor occupancy was statistically significantly higher in cortical (inferior tem…