When should clozapine be initiated in schizophrenia?: Some arguments for and against earlier use of clozapine

Association Between Clozapine Plasma Concentrations and Treatment Response: A Systematic Review, Meta-analysis and Individual Participant Data Meta-analysis

BACKGROUND AND OBJECTIVES

Although therapeutic drug monitoring of clozapine is recommended, its optimisation is often adjusted only on the basis of dosage. The aim of this study was to assess the link between clozapine plasma concentrations and clinical response by a meta-analysis of published studies and by an individual participant data meta-analysis.

METHODS

We conducted a computerised search of bibliographic databases (EMBASE, PubMed, Clinical Trials, and Web of Science) to identify studies that assessed the relationship between clozapine serum or plasma concentrations and clinical efficacy. Using pooled data, we investigated the association between improvement of clinical outcome and clozapine or norclozapine plasma concentrations, the sum of clozapine and norclozapine plasma concentrations, and the coefficient of variation of clozapine plasma concentrations. Using available individual data, we assessed the relationship between clozapine plasma concentrations and clinical response (changes in the Brief Psychiatric Rating Scale score) and identified a threshold level for a favourable clinical response.

RESULTS

Fifteen studies satisfied inclusion criteria. Our meta-analysis showed that responders had clozapine plasma concentrations that were, on average, 117 ng/mL higher than non-responders. The patients with plasma clozapine concentrations above the thresholds identified in each study had a higher likelihood of responding (odds ratio = 2.94, p < 0.001). Norclozapine plasma concentrations were not associated with a clinical response. The meta-analysis of individual data supported this result and confirmed the link between clozapine concentrations and a change in the Brief Psychiatric Rating Scale score and/or the probability of clinical response. Finally, with the analysis of the coefficient of variation of clozapine plasma concentrations, we found that a greater inter-individual fluctuation in plasma concentrations was associated with a loss of clinical response.

CONCLUSIONS

Our work confirmed that, in contrast to clozapine doses, clozapine plasma concentrations were related to a favourable clinical response, with a mean difference between responders and non-responders of 117 ng/mL. A threshold for a treatment response of 407 ng/mL was determined, with a high discriminatory capacity, and a sensitivity and specificity of 71% and 89.1%, respectively.

Clozapine and Norclozapine Plasma Levels in Patients Switched Between Different Liquid Formulations

BACKGROUND AND OBJECTIVE

Clozapine is the drug of choice for treatment-resistant schizophrenia. The primary objective of this study was to compare plasma clozapine and N-desmethylclozapine levels in patients switched between 2 liquid formulations [Denzapine suspension and clozapine oral solution (St George's ZTAS)]. Secondary objectives included comparison of safety, tolerability, and patient acceptability.

METHODS

This was a noninterventional, observational, prospective follow-up of patients consecutively switched between formulations of clozapine liquid in a large inner-city NHS mental health trust. The authors also performed retrospective analysis of outcomes from patient case notes.

RESULTS

The authors identified 43 patients receiving Denzapine suspension in the trust. Data were available for 43 patients switched from Denzapine to clozapine oral solution (St George's ZTAS), among whom, 15 (32%) were excluded from the analysis. Of the 28 patients for whom data were available, the 90% confidence interval for the ratio of mean values for corrected Cmin 91.5 (85.2%-98.4%) and uncorrected Cmin 91.2 (84.4%-98.6%) were within the guideline range of bioequivalence (80%-125%). Safety and tolerability profiles were comparable between the 2 formulations (P = 0.10). Patient acceptability was also similar between the brands in most domains. However, there was a taste preference for Denzapine suspension.

CONCLUSIONS

No significant difference in clozapine plasma levels was observed after switching from Denzapine suspension to a recently introduced clozapine solution. This study also highlights the significance of medicinal characteristics such as taste for patient acceptability and compliance.

Dopamine antagonist antipsychotics in diverted forensic populations

In community settings, negative symptoms and cognitive deficits are the primary barriers to independent living, stable relationships, and employment for individuals suffering from schizophrenia-spectrum disorders. In contrast, however, positive psychotic symptoms (e.g., command hallucinations and persecutory delusions) often drive behavior which serves as the gateway to arrest and criminalization. Historically, the keystone of treatment for positive psychotic symptoms has been antagonism of dopamine D2 receptors in the mesolimbic tract. In this article, we review and explore the principles underlying dopamine antagonism for the treatment of psychosis; optimization of dopamine antagonists in treating positive psychotic symptoms; the advantages of depot dopamine antagonist antipsychotics in forensic settings; the concepts of pharmacokinetic and pharmacodynamic treatment failures; and the role of medication plasma concentrations in optimizing and managing treatment.

Clozapine use in early psychosis

BACKGROUND

The superior efficacy of clozapine in treatment resistant schizophrenia has been clearly demonstrated, yet there are often delays in the commencement of clozapine. In this study, we aimed to determine; the proportion of young people with a first episode of psychosis (FEP) who would be considered eligible for clozapine treatment, the theoretical delay in commencing clozapine and to compare the outcomes of those treated with clozapine to those who were eligible but not treated with clozapine.

METHODS

This study was conducted at Orygen Youth Health (OYH), a youth mental health service for young people aged 15-24. All clients who were treated at the Early Psychosis Prevention and Intervention Centre (EPPIC) clinic between 01.01.2011 and 31.12.2013 were included.

RESULTS

544 young people presented with a FEP in the study period and 9.4% (N = 51) subsequently fulfilled criteria for treatment-resistant schizophrenia. Of these individuals, thirty (58.8%) were commenced on clozapine, in addition to a further eleven. The median delay to the commencement of clozapine was 42 weeks (I.Q.R. = 7.5-64). Of those commenced on clozapine, 76.6% achieved remission of positive psychotic symptoms and 50% were in employment or education by the time of discharge or transfer to the adult mental health services. The rate of discontinuation of clozapine was 24.4% and 60.0% of discontinuations were due to cardiac complications and the remainder were due to non-compliance.

CONCLUSIONS

These findings suggest that early intervention for psychosis services have a crucial role in ensuring timely initiation of clozapine in individuals with a diagnosis of treatment-resistant schizophrenia.

Pathway to clozapine use: a comparison between a patient cohort from New Zealand and a cohort from the United Kingdom

BACKGROUND AND OBJECTIVE

Clozapine has been available since the early 1990s. Studies continue to demonstrate its superior efficacy in treatment-resistant schizophrenia. Despite this, numerous studies show under-utilisation, delayed access and reluctance by psychiatrists to prescribe clozapine. This retrospective cross-sectional study compared the prescribing of clozapine in two adult cohorts under the care of large public mental health services in Auckland (New Zealand) and Birmingham (United Kingdom) on 31 March 2007.

METHOD

Time from first presentation to clozapine initiation, prior antipsychotics trialled and antipsychotic co-prescribing were compared. Data included demographics, psychiatric diagnosis, co-morbid conditions, year of first presentation, admissions and pharmacological treatment (clozapine dose, start date, prior antipsychotics, co-prescribed antipsychotic).

RESULTS

Overall, 664 people were prescribed clozapine (402 Auckland; 262 Birmingham); mean daily dose of 384 mg (Auckland) and 429 mg (Birmingham). 53 % presented after 1990 and the average duration of time before starting clozapine was significantly longer in the Birmingham cohort (6.5 vs. 5.3 years) but this reduced in both cohorts to a 1-year mean in those presenting within the last 3 years. The average number of antipsychotics trialled pre-clozapine for those presenting since 1990 was significantly higher in the Birmingham cohort (4.3 vs. 3.1) but in both cohorts this similarly reduced in those presenting within the last 3 years. Antipsychotic co-prescribing was significantly higher in the Birmingham cohort (22.9 vs. 10.7 %).

CONCLUSIONS

There is evidence that access to clozapine has improved over time in both cohorts, with a reduction in the duration between presentation and initiation of clozapine and number of different antipsychotics trialled pre-clozapine. These are very positive findings in terms of optimising outcomes with clozapine and are possibly due to the impact of guideline recommendations, increasing clinician, consumer and carer knowledge, and experience with clozapine and funding changes.

Detection and characteristics of individuals with a very long duration of untreated psychosis in an early intervention for psychosis service

AIM

Early intervention (EI) services for psychosis aim to reduce the duration of untreated psychosis (DUP) with intensive large-scale multi-focus initiatives, including public awareness campaigns. As a consequence of this approach, individuals with a very long DUP who might have otherwise remained undiagnosed may come to medical attention. The aim of this study was to investigate if an EI service detected additional cases of individuals with a first-episode psychosis (FEP) with a very long DUP and identify demographic and clinical characteristics associated with a very long DUP.

METHODS

We compared the distribution of the DUP in cases with FEP in a cohort from an EI service in a geographically defined catchment area with a historical control group. Participants were interviewed using the Structured Clinical Interview for DSM IV (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition) diagnoses and the Beiser scale to determine the DUP.

RESULTS

A total of 172 individuals were included in the EI service and 151 were included from the historical control. There was no difference in the distribution of the DUP in the EI service compared with the historical control group (χ(2)  = 3.77, degrees of freedom (d.f.) = 3, P = 0.29). In the EI service, 7.6% of cases had a DUP between 24 and 35.9 months compared to 3.3% in the historical control, and 13.4% of cases in the EI service had a DUP of greater than three years compared to 10.6% in the historical control. A very long DUP was associated with unemployment, less insight and involuntary treatment.

CONCLUSION

Further examination of the pathways to care in cases with a long DUP may clarify the contribution of help-seeking and health system delays for these individuals.

Volumetric changes in the basal ganglia after antipsychotic monotherapy: a systematic review

Introduction:

Exposure to antipsychotic medication has been extensively associated with structural brain changes in the basal ganglia (BG). Traditionally antipsychotics have been divided into first and second generation antipsychotics (FGAs and SGAs) however, the validity of this classification has become increasingly controversial. To address if specific antipsychotics induce differential effects on BG volumes or whether volumetric effects are explained by FGA or SGA classification, we reviewed longitudinal structural magnetic resonance imaging (MRI) studies investigating effects of antipsychotic monotherapy.

Material and Methods:

We systematically searched PubMed for longitudinal MRI studies of patients with schizophrenia or non-affective psychosis who had undergone a period of antipsychotic monotherapy. We used specific, predefined search terms and extracted studies were hand searched for additional studies.

Results:

We identified 13 studies published in the period from 1996 to 2011. Overall six compounds (two classified as FGAs and four as SGAs) have been investigated: haloperidol, zuclophentixol, risperidone, olanzapine, clozapine, and quetiapine. The follow-up period ranged from 3-24 months.

Unexpectedly, no studies found that specific FGAs induce significant BG volume increases. Conversely, both volumetric increases and decreases in the BG have been associated with SGA monotherapy.

Discussion:

Induction of striatal volume increases is not a specific feature of FGAs. Except for clozapine treatment in chronic patients, volume reductions are not restricted to specific SGAs.

The current review adds brain structural support to the notion that antipsychotics should no longer be classified as either FGAs or SGAs. Future clinical MRI studies should strive to elucidate effects of specific antipsychotic drugs.

High-resolution chromatography/time-of-flight MSE with in silico data mining is an information-rich approach to reactive metabolite screening

Electrophilic reactive metabolite screening by liquid chromatography/mass spectrometry (LC/MS) is commonly performed during drug discovery and early-stage drug development. Accurate mass spectrometry has excellent utility in this application, but sophisticated data processing strategies are essential to extract useful information. Herein, a unified approach to glutathione (GSH) trapped reactive metabolite screening with high-resolution LC/TOF MS(E) analysis and drug-conjugate-specific in silico data processing was applied to rapid analysis of test compounds without the need for stable- or radio-isotope-labeled trapping agents. Accurate mass defect filtering (MDF) with a C-heteroatom dealkylation algorithm dynamic with mass range was compared to linear MDF and shown to minimize false positive results. MS(E) data-filtering, time-alignment and data mining post-acquisition enabled detection of 53 GSH conjugates overall formed from 5 drugs. Automated comparison of sample and control data in conjunction with the mass defect filter enabled detection of several conjugates that were not evident with mass defect filtering alone. High- and low-energy MS(E) data were time-aligned to generate in silico product ion spectra which were successfully applied to structural elucidation of detected GSH conjugates. Pseudo neutral loss and precursor ion chromatograms derived post-acquisition demonstrated 50.9% potential coverage, at best, of the detected conjugates by any individual precursor or neutral loss scan type. In contrast with commonly applied neutral loss and precursor-based techniques, the unified method has the advantage of applicability across different classes of GSH conjugates. The unified method was also successfully applied to cyanide trapping analysis and has potential for application to alternate trapping agents.

Clozapine use and outcomes among patients with treatment resistant schizophrenia

OBJECTIVE

The phenomenology of patients with schizophrenia is similar world-wide, regardless of culture. However, the prognosis is variable both internationally and within national groups of patients. Furthermore, despite advances in pharmacological treatment, a significant proportion of patients with schizophrenia continue to show residual symptoms and disabilities due to poor response to antipsychotic medication. This study retrospectively assessed differences in outcome by gender, ethnicity and age among a group of treatment-resistant patients with schizophrenia.

METHOD

Patients in the catchment (350,000 people) of a single New Zealand public mental health provider (Waikato) formed the study group. Information concerning demographic profiles, Health of the Nation Outcome Scales (HoNOS) ratings and details of Clozapine usage were extracted from clinical records and the data base.

RESULTS

Gender, ethnicity and age did not emerge as significantly associated with any of the outcome variables except for the 30-40 year olds having more improvement on overactivity/aggression ratings than younger or older patients.

CONCLUSIONS

Despite these negative results in the New Zealand context, there remain many unanswered questions about the higher rate of service use by Maori. Replication of this study on a larger cohort of patients may be indicated before discarding the idea of potential links between ethnicity, treatment choice and outcomes.

Serotonin2A receptor blockade and clinical effect in first-episode schizophrenia patients treated with quetiapine

RATIONALE

We have previously reported decreased frontal cortical serotonin2A receptor binding in 30 antipsychotic naïve first-episode schizophrenic patients and a relationship between this binding and positive psychotic symptoms. Until now, no longitudinal studies of serotonin2A receptor in first-episode antipsychotic-naïve schizophrenia patients have reported on the relationship between serotonin2A receptor occupancy and treatment effect after sustained treatment with a specific atypical antipsychotic compound.

OBJECTIVES

Here, we measured serotonin2A receptor occupancy with [(18)F]altanserin PET in 15 first-episode antipsychotic-naïve schizophrenia patients before and after 6 months of quetiapine treatment. Moreover, we investigated possible relationships between clinical efficacy, oral dose, and plasma levels of quetiapine

RESULTS

Significant nonlinear relationships were found between serotonin2A receptor occupancy, quetiapine dose, and plasma concentration. There was a modest effect on positive symptoms up until a serotonin2A receptor occupancy level of approximately 60%. A receptor occupancy level between 60% and 70% appeared to exert the optimal serotonin2A receptor related treatment effect on positive symptoms whereas no additional serotonin2A receptor associated treatment effect was obtained above a receptor occupancy of 70%.

CONCLUSIONS

Taken together, the data point to a therapeutic role of the serotonin2A receptor in the treatment of subgroups of patients with schizophrenia. Specifically, the study indicates a serotonin2A receptor associated therapeutic window on positive symptoms in responding patients in the range between 60% and 70% occupancy in antipsychotic-naïve first-episode schizophrenia. We speculate that non-responding patients need higher dopamine D(2) receptor blockade. Future studies with concurrent measurement of interactions with the dopamine system are, however, warranted to clarify this.

Progressive striatal and hippocampal volume loss in initially antipsychotic-naive, first-episode schizophrenia patients treated with quetiapine: relationship to dose and symptoms

First-generation antipsychotics have been associated with striatal volume increases. The effects of second-generation antipsychotics (SGAs) on the striatum are unclear. Moreover, SGAs may have neuroprotective effects on the hippocampus. Dose-dependent volumetric effects of individual SGAs have scarcely been investigated. Here we investigated structural brain changes in antipsychotic-naive, first-episode schizophrenia patients after 6 months treatment with the SGA, quetiapine. We have recently reported on baseline volume reductions in the caudate nucleus and hippocampus. Baseline and follow-up T1-weighted images (3 T) from 22 patients and 28 matched healthy controls were analysed using tensor-based morphometry. Non-parametric voxel-wise group comparisons were performed. Small volume correction was employed for striatum, hippocampus and ventricles. Dose-dependent medication effects and associations with psychopathology were assessed. Patients had significant bilateral striatal and hippocampal loss over the 6-month treatment period. When compared to controls the striatal volume loss was most pronounced with low quetiapine doses and less apparent with high doses. Post-hoc analyses revealed that the striatal volume loss was most pronounced in the caudate and putamen, but not in accumbens. Conversely, hippocampal volume loss appeared more pronounced with high quetiapine doses than with low doses. Clinically, higher baseline positive symptoms were associated with more striatal and hippocampal loss over time. Although patients' ventricles did not change significantly, ventricular increases correlated with less improvement of negative symptoms. Progressive regional volume loss in quetiapine-treated, first-episode schizophrenia patients may be dose-dependent and clinically relevant. The mechanisms underlying progressive brain changes, specific antipsychotic compounds and clinical symptoms warrant further research.

Patterns of clozapine prescribing in a mental health service in New Zealand

OBJECTIVE

To describe clozapine prescribing in a mental health service in Auckland, New Zealand and compare it with national and international treatment guidelines.

SETTING

A large public mental health service for adults in Auckland, New Zealand.

METHOD

A retrospective cross-sectional study of all adult outpatients and stable inpatients being treated with clozapine on 31st March 2007 in one mental health service in Auckland, New Zealand. Data on patient characteristics, diagnosis, duration of illness, number of hospitalisations, legal status relating to their treatment, living situation, marital status and occupational activity were recorded from case notes. Data collected on clozapine included date of initiation, dose and duration of treatment. Prior antipsychotic use and information on all other psychotropic drugs prescribed was also collected. Data were entered into a custom-designed Microsoft Access database and analysed using SPSSv15.0.

MAIN OUTCOME MEASURES

Clozapine prescribing patterns and concordance with best practice recommendations for clozapine use.

RESULTS

402 adult mental health outpatients and stable inpatients were eligible for inclusion. The mean daily dose of clozapine was 383 (SD 166) mg. For those first presenting after universal government funding, the mean time between presentation and initiation of clozapine, was 2.8 (SD 1.9) years, compared to 5.7 (SD 3.3) years prior to funding. Of those presenting after universal government funding, approximately two-thirds (69.0%) had < or = 2 trials with other antipsychotics prior to commencing clozapine; of whom the majority (62.0%) received only second-generation antipsychotics (SGA). Both the number of antipsychotic agents trialled and the time to clozapine initiation has fallen since government subsidy was introduced in 1999. Based on a analysis of annualised hospitalization rates, it appears that shortening the delay to receiving clozapine leads to fewer hospitalisations in this treatment-resistant population, although this did not achieve statistical significance in our study.

CONCLUSIONS

Contemporary management of patients with treatment resistant schizophrenia in New Zealand is broadly in line with national and international best practice guidelines. There is some evidence, based on hospitalisation rates, to support the assertion that shorter delays in accessing clozapine leads to better outcomes. This needs further evaluation using measures of clinical outcome including objective measures of functioning.

Treatment Pathway and Patterns of Clozapine Prescribing for Schizophrenia in New Zealand

Objective:

To describe the treatment pathway and patterns of clozapine use in patients with schizophrenia, including coprescribed psychotropic medications, and compare the extent of coprescribing of clozapine with that of non-clozapine schizophrenia treatment in community montal health services in the Auckland and Northland regions of New Zealand.

Methods:

A retrospective chart review was conducted for adult outpatients receiving care from community mental health services on October 31, 2004. Data collected for all patients prescribed an antipsychotic included demographics (sex, age, ethnicity); principal diagnosis (Diagnostic and Statistical Manual of Mental Disorders, 4th edition); comorbid conditions; duration of mental illness; psychiatric admissions; and treatment information (psychotropic medications, with dose and route of administration). If clozapine had been started after the introduction of full government prescription subsidy (February 1999), additional data, including year of initiation and prior antipsychotic history, were collected. Analysis included all outpatients with a diagnosis of schizophrenia (including schizoaffective disorder).

Results:

Antipsychotics were prescribed for 2796 schizophrenia patients; 32.8% were prescribed clozapine, with a mean dose of 372 mg/day and an average duration of illness of 9.7 years before starting clozapine. Patients who had started treatment after clozapine was funded by the government (59.3%) had received a median of 3 antipsychotic drugs prior to starting clozapine; most of the treatment regimens included 1 second-generation antipsychotic (91.2%). Clozapine patients were less likely to be coprescribed another antipsychotic compared with non-clozapine patients (11.7% vs 17.6%; p conclusions: Outpatients with treatment-resistant schizophrenia were prescribed clozapine at expected rates; however, treatment was delayed longer than recommended. There is some evidence that access to clozapine for treatment-resistant schizophrenia has improved, possibly as the result of the introduction of government subsidy, guideline dissemination, or increasing experience of clinicians with use of clozapine. In this real-world environment, the number of concomitant psychotropic medications for outpatients with schizophrenia was found to be low; when used concomitantly with clozapine, they were most commonly used to manage adverse effects.