Predicting age-specific dosing of antipsychotics

Antipsychotic drug treatment of schizophrenia in later life: Results from the European cross-sectional AMSP study

OBJECTIVES

To investigate the relationship between patient age and the selection and dosage of antipsychotic drugs (APDs) for treatment of schizophrenia. We describe age effects for multiple individual APDs, thus allowing comparisons between drugs.

METHODS

Prescription data of 32,062 inpatients with schizophrenia from 2000 to 2017 were obtained from the Drug Safety Program in Psychiatry (AMSP) database. APD selection and dosage were related to patient age with sex as an influencing variable. Moreover, a systematic search of current guideline recommendations on APD treatment in patients with schizophrenia aged ≥65 years was performed.

RESULTS

Eighty percentof elderly patients (≥65 years) received a second-generation APD, most commonly risperidone. The dosage of APDs increased with age until about age 40 years, then decreased slowly at first and more steeply beyond age 55 years. The influence of age as well as sex on dosage partly differed between the individual drugs. Only one of eight schizophrenia guidelines systematically addressed specific aspects of pharmacotherapy in older adults.

CONCLUSIONS

In clinical routine, age has a significant impact on selection and dosing of APDs. Information on optimising pharmacotherapy in older adults with schizophrenia from clinical trials is needed. Guidelines should be improved regarding APD therapy specifically for older adults.

"MAP Bayesian modeling combining striatal dopamine receptor occupancy and plasma concentrations to optimize antipsychotic dose regimens in individual patients"

AIM

Develop a robust and user-friendly software tool for the prediction of dopamine D₂ receptor occupancy (RO) in patients with schizophrenia treated with either olanzapine or risperidone, in order to facilitate clinician exploration of the impact of treatment strategies on RO using sparse plasma concentration measurements.

METHODS

Previously developed population pharmacokinetic (PPK) models for olanzapine and risperidone were combined with a pharmacodynamic (PD) model for D2 RO and implemented in the R programming language. Maximum a posteriori (MAP) Bayesian estimation was used to provide predictions of plasma concentration and RO based on sparse concentration sampling. These predictions were then compared to observed plasma concentration and RO.

RESULTS

The average (standard deviation) response times of the tools, defined as the time required for the application to predict parameter values and display the output, were 2.8 (3.1) and 5.3 (4.3) seconds for olanzapine and risperidone, respectively. The mean error (95% confidence interval) and root mean squared error (RMSE, 95% CI) of predicted versus observed concentrations were 3.73 ng/mL (-2.42 - 9.87) and 10.816 ng/mL (6.71 - 14.93) for olanzapine, and 0.46 ng/mL (-4.56 - 5.47) and 6.68 ng/mL (3.57 - 9.78) for risperidone and its active metabolite (9-OH risperidone). Mean error and RMSE of RO were -1.47% (-4.65 - 1.69) and 5.80% (3.89 - 7.72) for olanzapine and -0.91% (-7.68 - 5.85) and 8.87% (4.56 - 13.17) for risperidone.

CONCLUSION

Our monitoring software predicts concentration-time profiles and the corresponding D₂ RO from sparsely-sampled concentration measurements in an accessible and accurate form.

Dopamine D2 Receptor Occupancy Estimated From Plasma Concentrations of Four Different Antipsychotics and the Subjective Experience of Physical and Mental Well-Being in Schizophrenia: Results From the Randomized NeSSy Trial

BACKGROUND

Impaired subjective well-being in schizophrenia patients treated with antipsychotics has often been linked inter alia to the antidopaminergic effects of medication. Thus, it is important to capture the association between striatal dopamine D2 receptor occupancy (D2-RO) and global subjective well-being. We examined this association using data from our multicenter, randomized, double-blind Neuroleptic Strategy Study (NeSSy).

METHODS

An innovative double randomization process was used for allocation of patients to the specific treatment groups. Plasma drug concentrations were measured after 6 and 24 weeks of treatment to obtain the estimated D2-RO (eD2-RO) relative to literature values. We made an exploratory analysis of associations between eD2-RO and subjective well-being scores. One hundred two blood samples from 69 patients were available for the analysis. Because of the lack of a satisfactory occupancy model for quetiapine, only haloperidol, flupentixol, and olanzapine treatment groups were pooled, whereas aripiprazole data were analyzed separately, because of its partial agonistic properties.

RESULTS

In the pooled antagonist group, eD2-RO correlated negatively with the summarized well-being score. In a more detailed analysis, this association could be confirmed for all first-generation antipsychotic-treated patients, but not for the separate second-generation antipsychotic groups. In the aripiprazole group, higher eD2-RO was associated with impaired physical well-being, but had no association with mental well-being.

CONCLUSIONS

Our results suggest that high plasma levels and consequently high occupancy at D2 receptors are disadvantageous for subjective well-being, as distinct from the objective extrapyramidal side effects. To minimize patients' malaise, which disfavors adherence, implementation of therapeutic drug monitoring in the clinical routine may be useful.

Model-Guided Antipsychotic Dose Reduction in Schizophrenia: A Pilot, Single-Blind Randomized Controlled Trial

PURPOSE/BACKGROUND

Patients with schizophrenia as well as their psychiatrists are hesitant to reduce the antipsychotic dose in fear of relapse. To overcome such dilemmas, we developed models to individually calculate an oral dose that corresponds to a given target dopamine D2 receptor occupancy.

METHODS/PROCEDURES

In this pilot, 52-week single-blind randomized controlled trial, 35 clinically stable patients with schizophrenia receiving either risperidone or olanzapine monotherapy were randomly assigned to dose reduction (n = 17) or dose maintenance group (n = 18). In the former group, baseline doses were reduced to the doses corresponding to 65% D2 occupancy (the lower end of therapeutic window) at trough that were calculated from randomly collected plasma concentrations using our models.

FINDINGS/RESULTS

In the dose reduction group, doses of risperidone and olanzapine were decreased from 4.2 ± 1.9 to 1.4 ± 0.4 and 12.8 ± 3.9 to 6.7 ± 1.8 mg/d, whereas the doses in the dose maintenance group were 4.3 ± 1.9 and 15.8 ± 4.6 mg/d, respectively. Twelve subjects (70.5%) and 13 subjects (72.2%) in the dose reduction and dose maintenance groups completed the study (P = 0.604), whereas 3 subjects (18.8%) and none dropped out because of clinical worsening in the dose reduction and dose maintenance groups, respectively. There were not significant differences in score changes in Positive and Negative Syndrome Scale between the 2 groups but in Positive subscale scores in the Clinical Global Impression-Schizophrenia (0.4 ± 0.7 in the dose reduction group vs -0.1 ± 0.7 in the dose maintenance group, P = 0.029).

IMPLICATIONS/CONCLUSIONS

Although our model-guided dose reduction strategy was found to be comparable with no-dose change in terms of dropout rates, safety issues have to be further examined.

Mental Health-Care Delivery for Older People in China: An Update of Challenges and Recent Clinical Research

China is facing rapid population aging and the country has the world's largest aging population. The rapid demographic shift in aging population is associated with many social and health problems, in particular mental health issues. The aim of this article is to summarize the challenges and recent progress in mental health-care delivery and clinical research for older people in China.

Review of serum prolactin levels as an antipsychotic-response biomarker

Antipsychotics acting as antagonists at dopamine D2 receptors concentrated in the striatum are the cornerstone of effective treatment of psychosis. Substantial progress in treating persons with schizophrenia could be achieved by the identification of biomarkers which reliably determine the lowest efficacious dose of antipsychotics. Prolactin levels have been considered a promising treatment-response biomarker due to dopamine’s regulation of serum prolactin levels through D2 receptors in the hypothalamic-pituitary pathway. Prolactin secretion in response antipsychotic administration is associated with the antipsychotics affinity for D2 receptors. This review assesses the available literature on the use of serum prolactin levels as an antipsychotic-response biomarker. Articles were identified through PubMed as well as the reference lists of full text articles available online. Relevant publications were summarized briefly to define the limitations and utility of serum prolactin levels as a tool for improving antipsychotic dosing. Serum prolactin levels in combination with prolactin-inducing potencies for each antipsychotic may help identify the lowest effective dose of antipsychotic medications. , In addition to the fact that prolactin secretion is dependent on serum antipsychotic levels and not brain levels, recent findings show that prolactin release is independent of the β-arrestin-2 pathway and GSK3β regulation, one branch of the pathway that has been implicated in antipsychotic efficacy. Therefore, serum prolactin is an indirect biomarker for treatment response. Further investigations are warranted to characterize prolactin-antipsychotic dose-response curves and systematically test the utility of measuring prolactin levels in patients to identify a person’s lowest efficacious dose.

Demographic and Clinical Profile of Patients With Dementia Receiving Electroconvulsive Therapy: A Case-Control Study

PURPOSE

Little is known about the clinical characteristics of patients with dementia receiving electroconvulsive therapy (ECT) for the treatment of behavioral symptoms. This study examined the demographic and clinical profile of patients with dementia receiving ECT in China.

METHODS

This was a retrospective, case-control study. The sample was composed of 23 patients with dementia treated with ECT and 71 sex- and age-matched controls treated for a period of 8 years (2007-2014) at the National Clinical Research Centre of Mental Disorders, China. Sociodemographic and clinical data were collected from the electronic chart management system.

RESULTS

Multiple logistic regression analysis revealed that ECT was independently associated with high risk for suicide at admission. The recorded indications for ECT included both high risk for suicide and aggressive behavior. Most patients responded to ECT satisfactorily (56.5%) or partially (34.8%) with only mild-moderate transient memory impairment (30.4%).

CONCLUSIONS

Although this is a preliminary study limited by the retrospective design and small sample size, findings suggest that ECT is an effective and safe therapeutic intervention to reduce the risk for suicide and aggressive behavior in dementia.

Dopamine D2/3 Receptor Occupancy Following Dose Reduction Is Predictable With Minimal Plasma Antipsychotic Concentrations: An Open-Label Clinical Trial

BACKGROUND

Population pharmacokinetics can predict antipsychotic blood concentrations at a given time point prior to a dosage change. Those predicted blood concentrations could be used to estimate the corresponding dopamine D2/3 receptors (D2/3R) occupancy by antipsychotics based on the tight relationship between blood and brain pharmacokinetics. However, this 2-step prediction has never been tested.

METHODS

Two blood samples were collected at separate time points from 32 clinically stable outpatients with schizophrenia (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition; mean ± SD age: 60.1 ± 7.3 years) to measure plasma concentrations of olanzapine or risperidone at baseline. Then, subjects underwent a dose reduction of olanzapine or risperidone and completed a [(11)C]-raclopride positron emission tomography scan to measure D2/3R occupancy in the putamen. The plasma concentration at the time of the scan was predicted with the 2 samples based on population pharmacokinetic model, using NONMEM. D2/3R occupancy was then estimated by incorporating the predicted plasma concentration in a hyperbole saturation model. The predicted occupancy was compared to the observed value.

RESULTS

The mean (95% CI) prediction errors for the prediction of D2/3R occupancy were -1.76% (-5.11 to 1.58) for olanzapine and 0.64% (-6.18 to 7.46) for risperidone. The observed and predicted D2/3R occupancy levels were highly correlated (r = 0.67, P = .001 for olanzapine; r = 0.67, P = .02 for risperidone).

CONCLUSIONS

D2/3R occupancy levels can be predicted from blood drug concentrations collected prior to dosage change. Although this 2-step model is subject to a small degree of error, it could be used to select oral doses aimed at achieving optimal D2/3R occupancy on an individual basis.

Use of electroconvulsive therapy in older Chinese psychiatric patients

OBJECTIVE

Little is known about the use of electroconvulsive therapy (ECT) in older Chinese psychiatric patients. This study examined the frequency of ECT and the demographic and clinical correlates in older psychiatric patients hospitalized in a large psychiatric institution in Beijing, China.

METHODS

This was a retrospective chart review of 2339 inpatients aged 60 years and older treated over a period of 8 years (2007-2013) in a university-affiliated psychiatric institution in Beijing. Sociodemographic and clinical data were collected from the electronic chart management system for discharged patients.

RESULTS

The rate of ECT use was 28.1% in the whole sample; 37.9% in those with bipolar disorders, 43.6% in major depression, 21.2% in schizophrenia, and 10.7% in other diagnoses. ECT ("ECT group") was associated with 60-65-year age group, high risk for suicide and low risk for falls at the time of admission, use of mood stabilizers and antidepressants, lack of health insurance, and having major medical conditions and diagnosis of major depression. The above significant correlates explained 24.9% of the variance of ECT use (p < 0.001).

CONCLUSIONS

In a major psychiatric hospital in China, the use of ECT was common among older patients. ECT use in older patients treated in other clinical settings warrants further investigations.

Challenging the need for sustained blockade of dopamine D₂ receptor estimated from antipsychotic plasma levels in the maintenance treatment of schizophrenia: A single-blind, randomized, controlled study

OBJECTIVE

Blockade of dopamine D₂ receptors with antipsychotics above 65% is associated with optimal chance of clinical response although recent data suggest a lower threshold for the maintenance treatment of schizophrenia. The objective of this study was to prospectively examine whether such continuous high blockade would be necessary for maintenance treatment.

METHOD

In this single-blind, 52-week, randomized controlled trial, clinically stable patients with schizophrenia receiving risperidone or olanzapine were randomly assigned to the continuous D₂ blockade (i.e. an estimated trough D2 blockade of >65%) or non-continuous blockade group (i.e. an estimated peak level of >65% with an estimated trough level of <65%). Oral doses corresponding to the assigned blockade levels were estimated from random plasma drug concentrations, using the models we developed; antipsychotic doses were then adjusted accordingly. Psychopathology and side effects were assessed at baseline and one year with the Positive and Negative Syndrome Scale (PANSS), Simpson-Angus Scale (SAS), and Abnormal Involuntary Movement Scale (AIMS).

RESULTS

Sixty-eight subjects (34 in each group) were enrolled. Twenty-six (76.5%) and thirty-one (91.2%) subjects completed the study in the continuous and non-continuous blockade groups, respectively, without any significant group difference. No significant differences were found on any of the assessment scales between the two groups. The degree of dosage change was small in both groups.

CONCLUSION

These results offer support that the threshold for D₂ receptor blockade in the maintenance treatment can be lower than 65%. However, these preliminary findings have to be confirmed through double-blind, larger scale trials with longer follow-up periods.

Common use of high doses of antipsychotic medications in older Asian patients with schizophrenia (2001-2009)

OBJECTIVE

This study aimed to examine the use of high doses of antipsychotic medications (≥600 mg/day chlorpromazine equivalent) in older Asian patients with schizophrenia and its demographic and clinical correlates.

METHOD

Information on hospitalized patients with schizophrenia aged ≥50 years was extracted from the database of the Research on Asian Psychotropic Prescription Patterns study (2001-2009). Data on 2203 patients in six Asian countries and territories, including China, Hong Kong, Japan, Korea, Singapore and Taiwan, were analyzed. Socio-demographic and clinical characteristics and antipsychotic prescriptions were recorded.

RESULTS

The frequency for high-dose antipsychotic medications was 36.0% overall, with 38.4% in 2001, 33.3% in 2004 and 36.0% in 2009. Multiple logistic regression analysis of the whole sample showed that compared to patients receiving low-medium antipsychotic doses, those on high doses had a longer illness duration (odds ratio (OR): 2.0, 95% confidence interval (CI):1.2-3.3, p = 0.008), were more likely in the 50-59-year group (OR: 0.95, 95% CI: 0.94-0.97, p < 0.001), more often had current positive (OR: 1.5, 95% CI: 1.2-1.8, p < 0.001) or negative symptoms (OR: 1.3, 95% CI: 1.03-1.6, p = 0.03), and more commonly received antipsychotic polypharmacy (OR: 5.3, 95% CI: 4.1-6.7, p < 0.001). Extrapyramidal symptoms (p = 0.25) and tardive dyskinesia (p = 0.92) were not more frequent in the high-dose group.

CONCLUSIONS

High doses of antipsychotic medications were used in more than one third of older Asian patients with schizophrenia. The reasons for the frequent use of high antipsychotic doses in older Asian patients warrant further investigation.

Tardive dyskinesia in relation to estimated dopamine D2 receptor occupancy in patients with schizophrenia: analysis of the CATIE data

OBJECTIVE

The objective of this study was to evaluate the relationship between antipsychotic-induced tardive dyskinesia (TD) and estimated dopamine D2 receptor occupancy levels in patients with schizophrenia, using the dataset from the Clinical Antipsychotic Trials in Intervention Effectiveness (CATIE).

METHODS

The dataset from 218 subjects (risperidone, N=78; olanzapine, N=100; ziprasidone, N=40) who presented with a score of zero on the Abnormal Involuntary Movement Scale (AIMS) at baseline in Phase 1 of the CATIE study, and remained for ≥6months, was used. Peak and trough dopamine D2 receptor occupancy levels on the day of the AIMS assessment at the endpoint were estimated from plasma antipsychotic concentrations, using population pharmacokinetic analysis and our D2 prediction model. The estimated dopamine D2 receptor occupancy levels were compared between patients who presented an AIMS score of ≥2 at endpoint and those with a score of zero, using the Mann-Whitney U test.

RESULTS

Estimated dopamine D2 receptor occupancy levels at trough were significantly higher in subjects who developed involuntary movements (N=23) than those who did not (N=195) (71.7±14.4% vs. 64.3±19.3%, p<0.05) while no significant difference was found in the estimated peak D2 receptor occupancy between them (75.4±8.7% vs. 72.1±9.9%, p=0.07). When the analyses were separately conducted for the three drugs, there were no significant differences in estimated peak or trough D2 occupancy although the values were consistently numerically higher among those developing involuntary movements.

CONCLUSION

Greater dopamine D2 receptor blockade with antipsychotics at trough might increase the risk of tardive involuntary movements although this finding needs to be replicated in larger trials.

Estimated dopamine D2 receptor occupancy from plasma concentrations of atypical antipsychotics and subjective experience/drug attitude in schizophrenia: an analysis of the CATIE data

OBJECTIVE

The objective of this analysis was to evaluate both cross-sectional and longitudinal relationships between estimated dopamine D2 receptor occupancy from plasma concentrations of atypical antipsychotics and subjective experience/drug attitude in patients with schizophrenia.

METHOD

The data from the Clinical Antipsychotic Trials in Intervention Effectiveness (CATIE) were used in this analysis. The cross-sectional data included 371 patients receiving risperidone, olanzapine, or ziprasidone, who had completed the Drug Attitude Inventory (DAI-10) at six months and provided plasma antipsychotic concentrations. Samples were analyzed to examine the relationship between DAI-10 total scores and estimated D2 occupancy using Spearman's rank correlations, followed by multiple regression analysis. In addition, to elucidate the relationship between changes in DAI-10 scores and estimated D2 occupancy, the longitudinal data from 45 patients who experienced an increase in antipsychotic dosage between six and 12months were analyzed. Mean peak and trough D2 occupancy levels were estimated from plasma antipsychotic concentrations using a population pharmacokinetic approach.

RESULTS

A positive association was found between estimated D2 occupancy and DAI-10 total scores in patients receiving ziprasidone in the cross-sectional dataset (rs=0.395, P=0.001). In contrast, a negative association was found in changes in estimated D2 occupancy and DAI-10 scores among patients receiving olanzapine in the longitudinal dataset (rs=-0.534, P=0.010). No significant associations were found in patients receiving risperidone, or in the whole sample regarding both cross-sectional and longitudinal datasets.

CONCLUSION

Dopamine D2 receptor occupancy may mediate subjective experience/drug attitude in patients with schizophrenia. The directionality may however differ between antipsychotics, which warrants further investigation.

Estimated dopamine D₂ receptor occupancy and remission in schizophrenia: analysis of the CATIE data

In treating schizophrenia, 65% to 80% occupancy of dopamine D₂ receptors optimizes therapeutic efficacy while minimizing risks of extrapyramidal symptoms and cognitive impairments. However, it is unclear as to whether it is necessary to keep D₂ receptor occupancy within this therapeutic window to maintain clinical response. The data set from phase 1 of the Clinical Antipsychotic Trials in Intervention Effectiveness (CATIE) trial was reappraised. Thirty patients receiving risperidone (12 patients), olanzapine (12 patients), or ziprasidone (6 patients) fulfilled the following definition of remission and were included: a score of 3 or less on the 8 specific items in the Positive and Negative Syndrome Scale (ie, P1, P2, P3, N1, N4, N6, G5, and G9; adopted from Andreasen et al, 2005) at the initial assessment and months 1, 2, and 6. Peak and trough D₂ receptor occupancy levels at month 6 were estimated from plasma antipsychotic concentrations using population pharmacokinetic analysis and our D₂ prediction model. Estimated mean ± SD peak and trough D₂ receptor occupancy levels at month 6 were 70.3% ± 9.8% and 60.5% ± 20.2%, respectively; among these individuals, 46.7% (14 patients) did not achieve continuous blockade of 65% or greater (ie, trough D₂ occupancy of <65%). In conclusion, approximately half of patients with remission did not achieve continuous blockade of estimated D₂ receptor occupancy 5% or greater. These results extend our previous findings and suggest that sustained D₂ receptor occupancy greater than 65% may not always be necessary for the maintenance treatment of schizophrenia.

Hyperprolactinemia and estimated dopamine D2 receptor occupancy in patients with schizophrenia: analysis of the CATIE data

BACKGROUND

Large-scale data are still lacking on the relationship between serum prolactin concentration and dopamine D2 receptor occupancy in patients with schizophrenia treated with antipsychotics.

METHODS

The dataset from 481 subjects (risperidone, N = 172, olanzapine, N = 211, and ziprasidone, N = 98) who participated in Phase 1 of the Clinical Antipsychotic Trials in Intervention Effectiveness (CATIE) was used in the present analysis. Dopamine D2 receptor occupancy levels on the day of the measurement of serum prolactin level were estimated from plasma antipsychotic concentrations. A multivariate general linear model was used to examine effects of clinical and demographic characteristics, including estimated D2 occupancy levels, on serum prolactin concentrations. Individual subjects were divided into two groups, stratified by the presence of hyperprolactinemia. To evaluate the performance of this binary classification, sensitivity, specificity, and accuracy of consecutive cut-off points in the D2 occupancy were calculated.

RESULTS

The multivariate general linear model revealed that estimated D2 occupancy levels had significant effects on serum prolactin concentrations while any other variables failed to show significant effects. The cut-off point associated with 0.5 or greater, in both sensitivity and specificity with the greatest accuracy, was 73% (sensitivity, 0.58; specificity, 0.68; accuracy = 0.64) (68-70% for risperidone, 77% for olanzapine, and 55% for ziprasidone.).

CONCLUSION

The threshold for hyperprolactinemia in D2 occupancy may lie somewhat on a lower side of the established therapeutic window with antipsychotics (i.e. 65-80%). This finding highlights the need for the use of the lowest possible dose to avoid this hormonal side effect in the treatment of schizophrenia.

Use of clozapine in older Asian patients with schizophrenia between 2001 and 2009

BACKGROUND

To date there has been no large-scale international study that examined the use of clozapine in older patients with schizophrenia. This study examined the use of clozapine and its demographic and clinical correlates in older patients with schizophrenia in East Asia during the period between 2001 and 2009.

METHOD

Information on 1,157 hospitalized patients with schizophrenia aged 50 or older in five East Asian countries and territories (China, Hong Kong, Korea, Singapore and Taiwan) was extracted from the database of the Research on Asian Psychotropic Prescription Patterns (REAP) project. Socio-demographic and clinical characteristics and prescription of psychotropic medications were recorded.

RESULTS

Clozapine was prescribed for 20.6% of the pooled sample; 19.0% in 2001, 19.4% in 2004 and 22.9% in 2009. Multiple logistic regression analysis of the whole sample revealed that patients taking clozapine had a longer duration of illness, more negative symptoms and were less likely to receive first generation antipsychotic and anticholinergic drugs, but more likely to report weight gain compared to those not receiving clozapine. Compared to those in other sites, older patients in China were more likely to receive clozapine.

CONCLUSIONS

The prescription of clozapine for older Asian schizophrenia inpatients has remained at a stable level during the past decade. The appropriateness of use of clozapine in China needs to be further explored.

Dopamine D2 receptor occupancy and cognition in schizophrenia: analysis of the CATIE data

INTRODUCTION

Antipsychotic drugs exert antipsychotic effects by blocking dopamine D2 receptors in the treatment of schizophrenia. However, effects of D2 receptor blockade on neurocognitive function still remain to be elucidated. The objective of this analysis was to evaluate impacts of estimated dopamine D2 receptor occupancy with antipsychotic drugs on several domains of neurocognitive function in patients with schizophrenia in the Clinical Antipsychotic Trials in Intervention Effectiveness (CATIE) trial.

METHODS

The dataset from the CATIE trial was used in the present analysis. Data were extracted from 410 subjects who were treated with risperidone, olanzapine, or ziprasidone, received assessments for neurocognitive functions (verbal memory, vigilance, processing speed, reasoning, and working memory) and psychopathology, and provided plasma samples for the measurement of plasma antipsychotic concentrations. D2 receptor occupancy levels on the day of neurocognitive assessment were estimated from plasma antipsychotic concentrations, using population pharmacokinetic analysis and our recently developed model. A multivariate general linear model was used to examine effects of clinical and demographic characteristics, including estimated D2 occupancy levels, on neurocognitive functions.

RESULTS

D2 occupancy levels showed significant associations with the vigilance and the summary scores. Neurocognitive functions, including vigilance, were especially impaired in subjects who showed D2 receptor occupancy level of >77%.

DISCUSSION

These findings suggest a nonlinear relationship between prescribed antipsychotic doses and overall neurocognitive function and vigilance. This study shows that D2 occupancy above approximately 80% not only increases the risk for extrapyramidal side effects as consistently reported in the literature but also increases the risk for cognitive impairment.

Common use of anticholinergic medications in older patients with schizophrenia: findings of the Research on Asian Psychotropic Prescription Pattern (REAP) study, 2001-2009

OBJECTIVE

This study surveyed the use of anticholinergic medications (ACMs) in older Asian patients with schizophrenia and examined its demographic and clinical correlates.

METHOD

A total of 1452 hospitalized patients with schizophrenia aged 55 years or older in nine Asian countries and territories were surveyed between 2001 and 2009. The cross-sectional data of patients' socio-demographic and clinical characteristics and the prescriptions of antipsychotic drugs and ACM were recorded using a standardized protocol and data collection procedure.

RESULTS

The frequency of ACM prescription was 64.6% in the pooled sample, with 72.4%, 61.9%, and 59.5% in 2001, 2004, and 2009, respectively. Multiple logistic regression analysis of the whole sample revealed that patients on ACM had a higher dose of antipsychotic medications, and were more likely to have extrapyramidal side effects and receive first-generation antipsychotic medications.

CONCLUSIONS

Anticholinergic medications were frequently used in older Asian patients with schizophrenia. Considering the potential side effects of ACM, the rationale for their widespread use in this patient population should be revisited.

Common use of antipsychotic polypharmacy in older Asian patients with schizophrenia (2001-2009)

OBJECTIVE

The aim of this study was to survey the use of antipsychotic polypharmacy (APP) in older Asian patients with schizophrenia and examine its demographic and clinical correlates.

METHODS

Information on hospitalized patients with schizophrenia aged 55 or older was extracted from the database of the Research on Asian Psychotropic Prescription Patterns study. Data on 1439 patients in 6 Asian countries and territories including China, Hong Kong, Japan, Korea, Singapore, and Taiwan were analyzed. Sociodemographic and clinical characteristics and antipsychotic prescriptions were recorded using a standardized protocol and data collection procedure.

RESULTS

The frequency of APP prescription was 51.6% in the pooled sample with wide intercountry variations. Multiple logistic regression analysis of the whole sample showed that patients on APP had higher antipsychotic doses and also were more likely to receive first-generation antipsychotics.

CONCLUSIONS

Use of APP was common in older Asian patients with schizophrenia. Given the limited evidence supporting its efficacy, the potentially severe side effects and high costs, APP should be used with caution in this population. The reasons for and outcomes of the use of APP in this patient population merit further exploration.

Use of first- and second-generation antipsychotic medications in older patients with schizophrenia in Asia (2001-2009)

OBJECTIVE

This study examined the prescribing patterns of several first- (FGAs) and second-generation antipsychotic (SGAs) medications administered to older Asian patients with schizophrenia during the period between 2001 and 2009.

METHOD

Information on hospitalized patients with schizophrenia aged 65 or older was extracted from the database of the Research on Asian Psychotropic Prescription Patterns (REAP) study (2001-2009). There were no older patients in Thailand, therefore data on 467 patients in eight Asian countries and territories including China, Hong Kong SAR, India, Japan, Korea, Malaysia, Singapore, and Taiwan were analysed. Cross-sectional socio-demographic data, clinical characteristics and antipsychotic prescriptions were assessed using a standardized protocol and data collection procedure.

RESULTS

Of the 467 patients, 192 patients (41.1%) received FGAs only, 166 (35.5%) received SGAs only and 109 (23.3%) received a combination of FGAs and SGAs. Of the FGAs, haloperidol was the most commonly used (31.3%; mean 9.4 ± 6.7 mg/day), followed by chlorpromazine (15.4%; mean 126.4 ± 156.4 mg/day) and sulpiride (6.6%; mean 375.0 ± 287.0 mg/day). Of the SGAs, risperidone was the most commonly used (31.5%; mean 4.5 ± 2.7 mg/day), followed by olanzapine (13.1%; mean 13.6 ± 6.5 mg/day), quetiapine (7.3%; mean 325.0 ± 237.3 mg/day) and aripiprazole (1.9%; mean 17.6 ± 7.7 mg/day).

CONCLUSIONS

FGAs and higher doses of certain SGAs (risperidone, olanzapine and quetiapine) were still commonly dispensed to older Asian patients with schizophrenia. Considering older patients' reduced tolerability of potentially severe side effects associated with FGAs and higher doses of certain SGAs, continuing education and training addressing the rational use of antipsychotics in this population is clearly needed.

Predicting plasma concentration of risperidone associated with dosage change: a population pharmacokinetic study

BACKGROUND

Due to high interindividual variability in peripheral pharmacokinetic parameters, dosing of antipsychotics relies on clinical trial and error. This blind process of upward or downward clinical dose titration carries a risk of relapse and adverse effects in the treatment of schizophrenia. Using population pharmacokinetic methods, the authors therefore sought to predict plasma concentrations of risperidone (RIS) plus 9-hydroxyrisperidone (9-OH-RIS) before a dosage change.

METHODS

Two plasma samples were collected at 2 separate given time points for the measurement of RIS and 9-OH-RIS concentrations from 50 patients with schizophrenia or schizoaffective disorder maintained on risperidone (mean ± SD age = 56 ± 15 years; 39 men). After an oral risperidone dose adjustment, a third sample was collected. The plasma concentration of the third sample was individually predicted in a blinded fashion with the 2 baseline plasma concentrations before dose adjustment and clinical and demographic information, using the mixed-effects model with NONMEM that was derived from the data of the Clinical Antipsychotic Trials in Intervention Effectiveness study.

RESULTS

The mean (95% confidence interval) prediction errors (in ng/mL) were as low as 0.0 (-1.3 to 1.4) for RIS and 1.0 (-1.1 to 3.0) for 9-OH-RIS. The observed and predicted concentrations of RIS and 9-OH-RIS were highly correlated (r = 0.96, P < 0.0001 and r = 0.92, P < 0.0001, respectively).

CONCLUSIONS

Antipsychotic plasma concentrations can be predicted before risperidone dose adjustment. In light of the known relationship between plasma drug concentration, dopamine D2 receptor occupancy, and clinical effects, our results confirm that individualized dosing with the measurement of antipsychotic plasma concentrations has the potential for bedside clinical application.

Management of schizophrenia in late life with antipsychotic medications: a qualitative review

Although patients with schizophrenia are reported to have excess mortality compared with the general population, many affected patients will nonetheless survive and continue to have the disorder in later life. Consequently, geriatric schizophrenia will be a significant public health concern in the years to come, and evidence-based treatment of schizophrenia in older patients is becoming an urgent issue. However, there has been a paucity of comparative data to guide selection of antipsychotics for schizophrenia in late life. The primary aim of this review was to synthesize the available evidence on management of late-life schizophrenia with antipsychotic medications; a secondary aim was to evaluate treatment resistance in this population. Accordingly, PubMed and EMBASE were searched using the keywords 'antipsychotics', 'age' and 'schizophrenia' to identify psychopharmacological studies of antipsychotics in late-life schizophrenia (last search 30 April 2011). The literature search identified 23 prospective studies of use of antipsychotics for schizophrenia in older patients (generally age ≥65 years), including eight double-blind trials. The sample size was smaller than 40 patients for 52% of the studies. Two of the double-blind studies were post hoc analyses and one was a placebo-controlled trial. In the largest double-blind study, olanzapine (n = 88, median dose 10 mg/day) and risperidone (n = 87, median dose 2 mg/day) were compared in patients not resistant to these therapies, with similar effects. There have also been several open-label trials of these two agents that have shown efficacy and tolerability in non-resistant patients. Evidence on other antipsychotics has been scarce and less robust. The gold standard for treatment-resistant schizophrenia is clozapine. However, almost all of the studies of clozapine to date have effectively excluded older patients with schizophrenia. Only one small study has evaluated clozapine (n = 24, mean dose 300 mg/day) in comparison with chlorpromazine (n = 18, mean dose 600 mg/day) in a difficult-to-treat older population; the investigators reported that both treatments were similarly efficacious. Furthermore, there has been little compelling evidence in favour of or against augmentation of antipsychotics with other psychotropic medications in the older age group. Treatment of non-resistant, late-life schizophrenia with olanzapine and risperidone appears to be supported by the available evidence. However, data on geriatric patients with schizophrenia are generally scarce, particularly for treatment-resistant subpopulations, underscoring the need for more research in this important area.

Prescribing patterns of low doses of antipsychotic medications in older Asian patients with schizophrenia, 2001-2009

BACKGROUND

This study examined the use of low doses of antipsychotic medications (300 mg/day CPZeq or less) in older Asian patients with schizophrenia and its demographic and clinical correlates.

METHODS

Information on hospitalized patients with schizophrenia, aged 55 years or older, was extracted from the database of the Research on Asian Psychotropic Prescription Patterns (REAP) study (2001-2009). Data on 1,452 patients in eight Asian countries and territories including China, Hong Kong, Japan, Korea, Singapore, Taiwan, India, and Malaysia were analyzed. Sociodemographic and clinical characteristics and antipsychotic prescriptions were recorded using a standardized protocol and data collection procedure.

RESULTS

The prescription frequency for low doses of antipsychotic medications was 40.9% in the pooled sample. Multiple logistic regression analysis of the whole sample showed that patients on low doses of antipsychotic medications were more likely to be female, have an older age, a shorter length of illness, and less positive symptoms. Of patients in the six countries and territories that participated in all the surveys between 2001 and 2009, those in Japan were less likely to receive low doses of antipsychotics.

CONCLUSION

Low doses of antipsychotic medications were only applied in less than half of older Asian patients with schizophrenia.

Dopamine D2 receptor occupancy with risperidone or olanzapine during maintenance treatment of schizophrenia: a cross-sectional study

In treating schizophrenia, it has been established that 65-80% occupancy of dopamine D2 receptors optimizes therapeutic efficacy while minimizing risks of extrapyramidal symptoms. However, it is unclear as to whether it is necessary to keep D2 receptor occupancy within this therapeutic window to maintain response. In this study, daily peak and trough D2 receptor occupancy levels were estimated in clinically stable patients with schizophrenia (DSM-IV) who were receiving risperidone or olanzapine. Using two collected plasma samples, plasma antipsychotic concentrations at peak and trough were estimated with population pharmacokinetic techniques. Corresponding dopamine D2 receptor occupancy levels were then estimated, using a recently developed model. 35 subjects with stable schizophrenia completed the study (mean±SD age, 48.8±13.8years; male [N=14]; Asians [N=23], Caucasians [N=12]; risperidone [N=20] at 3.2±2.3mg/day, and olanzapine [N=15] at 9.2±4.9mg/day) between September and December 2010. 48.6% (N=17) did not achieve a continuous blockade of ≥65%. Moreover, 11.4% (N=4) did not achieve the 65% threshold at estimated peak concentrations. In conclusion, approximately half the subjects with stable schizophrenia did not achieve estimated continuous blockade of D2 receptor occupancy of ≥65%. The results suggest that sustained D2 receptor occupancy levels of ≥65% may not always be necessary for the maintenance treatment of schizophrenia.

Metabolomic profiling to identify potential serum biomarkers for schizophrenia and risperidone action

Despite recent advances in understanding the pathophysiology of schizophrenia and the mechanisms of antipsychotic drug action, the development of biomarkers for diagnosis and therapeutic monitoring in schizophrenia remains challenging. Metabolomics provides a powerful approach to discover diagnostic and therapeutic biomarkers by analyzing global changes in an individual's metabolic profile in response to pathophysiological stimuli or drug intervention. In this study, we performed gas chromatography-mass spectrometry based metabolomic profiling in serum of unmedicated schizophrenic patients before and after an 8-week risperidone monotherapy, to detect potential biomarkers associated with schizophrenia and risperidone treatment. Twenty-two marker metabolites contributing to the complete separation of schizophrenic patients from matched healthy controls were identified, with citrate, palmitic acid, myo-inositol, and allantoin exhibiting the best combined classification performance. Twenty marker metabolites contributing to the complete separation between posttreatment and pretreatment patients were identified, with myo-inositol, uric acid, and tryptophan showing the maximum combined classification performance. Metabolic pathways including energy metabolism, antioxidant defense systems, neurotransmitter metabolism, fatty acid biosynthesis, and phospholipid metabolism were found to be disturbed in schizophrenic patients and partially normalized following risperidone therapy. Further study of these metabolites may facilitate the development of noninvasive biomarkers and more efficient therapeutic strategies for schizophrenia.

Structural models describing placebo treatment effects in schizophrenia and other neuropsychiatric disorders

Large variation in placebo response within and among clinical trials can substantially affect conclusions about the efficacy of new medications in psychiatry. Developing a robust placebo model to describe the placebo response is important to facilitate quantification of drug effects, and eventually to guide the design of clinical trials for psychiatric treatment via a model-based simulation approach. In addition, high dropout rates are very common in the placebo arm of psychiatric clinical trials. While developing models to evaluate the effect of placebo response, the data from patients who drop out of the trial should be considered for accurate interpretation of the results. The objective of this paper is to review the various empirical and semi-mechanistic models that have been used to quantify the placebo response in schizophrenia trials. Pros and cons of each placebo model are discussed. Additionally, placebo models used in other neuropsychiatric disorders like depression, Alzheimer's disease and Parkinson's disease are also reviewed with the objective of finding those placebo models that could be useful for clinical studies of both acute and chronic schizophrenic disease conditions. Better understanding of the patterns of dropout and the factors leading to dropouts are crucial in identifying the true placebo response. We therefore also review dropout models that are used in the development of models for treatment effects and in the optimization of clinical trials by simulation approaches. The use of an appropriate modelling strategy that is capable of identifying the potential sources of variable placebo responses and dropout rates is recommended for improving the sensitivity in discriminating between the effects of active treatment and placebo.

The evolution of antipsychotic switch and polypharmacy in natural practice--a longitudinal perspective

OBJECTIVE

Most patients with schizophrenia first start with a single antipsychotic, and yet most finally end up 'switching' or using 'polypharmacy'. The objective of this study was to examine the evolution of antipsychotic switch and polypharmacy in the real-world from a longitudinal perspective.

METHODS

A systematic review of longitudinal antipsychotic prescriptions in 300 patients with schizophrenia (ICD-10) for up to 2 years after their first visit to one of the 4 participating psychiatric clinics in Tokyo, Japan between January, 2007 and June, 2008, was conducted. Reasons for prescription change were also examined. The evolution of switching and polypharmacy was studied, and prescribed doses were compared to suggested dose ranges by the Texas Medication Algorithm Project (TMAP).

RESULTS

208 patients started their antipsychotic treatment with monotherapy. 34.1% of the patients gave up monotherapy with an initial antipsychotic to move to antipsychotic switch (27.4%) and/or polypharmacy (17.8%) within 2 years. The main reason for antipsychotic switch was 'ineffectiveness'; interestingly, this happened despite the fact that the monotherapy dose was below the recommended range in 47.4% of the antipsychotic switch. In a subgroup of 100 patients who started as antipsychotic-free, 2-year prevalence rates of switching and antipsychotic polypharmacy were 27.0% and 18.0%, respectively, and polypharmacy was resorted to after a median of 1 antipsychotic had been tried for 84 days (median).

CONCLUSIONS

These findings raise a concern that physicians may perform an antipsychotic switch without exploring the entire dose range and resort to antipsychotic polypharmacy without trying an adequate number of antipsychotics.

Dopamine D2 receptor occupancy and clinical effects: a systematic review and pooled analysis

Positron emission tomography (PET) studies proposed a therapeutic window of D2 receptor occupancy (65%-80%) of antipsychotics for the treatment of schizophrenia in young adults. However, this conclusion has been drawn from clinical PET studies using small sample sizes (<20). Prospective PET studies that measured D2 occupancy levels and assessed extrapyramidal side effects (EPS) and/or treatment response induced by antipsychotics (excluding partial agonists) were identified, using MEDLINE and EMBASE (last search: March 2010). Individual subjects were divided into 2 groups based on EPS status (ie, presence or lack of newly emergent EPS) and treatment response (ie, a ≥ 25% or ≥ 50% reduction in the Positive and Negative Syndrome Scale or Brief Psychiatric Rating Scale). To evaluate the performance of this binary classification, sensitivity, specificity, and accuracy of consecutive cutoff points in the D2 occupancy were calculated: Accuracy = (True Positive + True Negative) / Total N. Twelve studies, including a total of 82 subjects, were included in our analyses. The cutoff points associated with 0.5 or greater in both sensitivity and specificity with the greatest accuracy were 77% to 78% for EPS, 60% for a 25% or greater symptom reduction, and 72% for a 50% or greater symptom reduction. These findings support the presence of a therapeutic window of 60% to 78% D2 occupancy of antipsychotics in young adults with schizophrenia and may suggest the presence of a continuum of effectiveness with increasing occupancy within this therapeutic window.

Low dose vs standard dose of antipsychotics for relapse prevention in schizophrenia: meta-analysis

BACKGROUND

It remains unknown as to whether the antipsychotic dose needed for the acute-phase treatment of schizophrenia is also necessary for relapse prevention.

AIM

To compare the efficacy between standard dose [(World Health Organization daily defined dose (DDD)] vs low dose (≥50% to <1 DDD) or very low dose (<50% DDD) for relapse prevention in schizophrenia.

DATA SOURCE

Double-blind, randomized, controlled trials with a follow-up duration of ≥24 weeks, including ≥2 dosage groups of the same antipsychotic drug for relapse prevention in schizophrenia, were searched using MEDLINE, the Cochrane Central Register of Controlled Trials, and EMBASE (last search: August 2009).

DATA EXTRACTION

Data on overall treatment failure, hospitalization, relapse, and dropouts due to side effects were extracted and combined in a meta-analysis.

DATA SYNTHESIS

Thirteen studies with 1395 subjects were included in this meta-analysis. Compared with the standard-dose treatment, the low-dose therapy did not show any statistically significant difference in overall treatment failure or hospitalization, while the standard dose showed a trend-level (P = .05) superiority in risk of relapse. The very low-dose group was inferior to the standard-dose group in all efficacy parameters. No significant difference was found in the rate of dropouts due to side effects between either standard dose vs low dose or very low dose.

CONCLUSIONS

Although antipsychotic treatment with ≥50% to <1 DDD may be as effective as standard-dose therapy, there are insufficient clinical trial data to draw firm conclusions on standard- vs low-dose maintenance antipsychotic therapy for schizophrenia.

Predicting dopamine D₂ receptor occupancy from plasma levels of antipsychotic drugs: a systematic review and pooled analysis

Measuring dopamine D₂ receptor occupancy levels using positron emission tomography (PET) is still widely unavailable. The objective of this study was to evaluate the accuracy of predicting D2 occupancy from the antipsychotic plasma level in patients with schizophrenia. Positron emission tomographic studies that measured plasma levels of antipsychotics and their corresponding D₂ occupancy levels were identified, using MEDLINE and EMBASE (last search: March 2010). Antipsychotics that were investigated in a total of 20 subjects or more were included. All data points for each antipsychotic were fit to a one-site binding model to estimate the total plasma concentration of each antipsychotic associated with a 50% occupancy (ED₅₀) of brain D₂ receptors. The mean prediction error and the root mean squared prediction error were used to measure the predictive performance of individual D₂ receptor occupancies from plasma drug levels derived from a one-site occupancy model using an ED₅₀ value calculated for each data point. A total of 34 treatment arms from 23 studies involving 281 subjects were included. The mean (95% confidence interval) prediction errors and root squared prediction errors were as low as 0.0 (-1.8 to 1.8) and 8.9 (7.6-10.2) for risperidone (n = 98); 0.0 (-3.5 to 3.5) and 15.1 (12.9-17.3) for clozapine (n = 75); -0.1 (-1.2 to 1.2), 0.0 (-1.9 to 1.9), and 4.6 (3.5-5.8) for olanzapine (n = 42); 0.1 (-3.4 to 3.5) and 9.9 (7.3-12.5) for haloperidol (n = 35); and -0.1 (-3.3 to 3.1) and 12.3 (8.8-15.7) for ziprasidone (n = 31), respectively. These findings suggest that D₂ occupancy of antipsychotics could be estimated with a high degree of accuracy using widely available plasma levels.

A tipping point in drug dosing in late-life schizophrenia

Minimally effective doses of antipsychotics are likely influenced by several clinical and demographic characteristics of patients, with age being one of the most important elements. In light of age-related physiologic changes as well as interindividual differences in pharmacokinetic and pharmacodynamic systems, individualized dosing with regard to age will be critically important for safer drug treatment for older patients with schizophrenia. In the present review, we propose the following cautious psychopharmacologic interventions for this population: 1) simple regimen (avoid polypharmacy), 2) be aware of the presence of patients who are very sensitive to drugs, 3) gradual dose titration, and 4) timely and thorough assessments of therapeutic and side effects. The age-related antipsychotic sensitivity highlights the importance of finding the lowest possible effective dose of antipsychotic drugs as patients with schizophrenia age to maximize therapeutic effects and minimize side effects.

Clinical and demographic characteristics associated with postural instability in patients with schizophrenia

As people with schizophrenia grow older, prevention of falls in this older population has become a public health priority. It is therefore critically important to identify risk factors to effectively prevent falls. For this purpose, the degree of postural sway can serve as a convenient index of risk assessment. The objective of this study was to find clinical and demographic characteristics associated with postural instability. Inpatients and outpatients with schizophrenia or related psychosis were recruited at 2 hospitals in Japan. The clinical stabilometric platform, which measured a range of the trunk motion, and extrapyramidal side effects were evaluated between 9 and 11 A.M. Four hundred two subjects were enrolled (age: mean, 55.5 [SD, 14.4] years). A univariate general linear model showed that the use of antipsychotic drugs with a chlorpromazine equivalent of 10 or greater, being overweight, and inpatient treatment setting were associated with a greater degree of the range of postural sway. Another general linear model, including a subgroup of 300 subjects who did not present any extrapyramidal side effects, not only consolidated these findings, but also revealed a great degree of postural sway in older subjects. In addition, quetiapine was found to be associated with a greater range of postural sway among atypical antipsychotics. Schizophrenia patients generally showed a greater degree of postural instability, compared with the reference data of healthy people. These findings highlight truncal instability as a risk factor of falls in patients with schizophrenia, especially when they are overweight, old, and/or receiving antipsychotics with a chlorpromazine equivalent of 10 or greater, including quetiapine.