Effects of age and gender on the serum levels of clozapine, olanzapine, risperidone, and quetiapine

Personalized venlafaxine dose prediction using artificial intelligence technology: a retrospective analysis based on real-world data

BACKGROUND

Venlafaxine dose regimens vary considerably between individuals, requiring personalized dosing.

AIM

This study aimed to identify dose-related influencing factors of venlafaxine through real-world data analysis and to construct a personalized dose model using advanced artificial intelligence techniques.

METHOD

We conducted a retrospective study on patients with depression treated with venlafaxine. Significant variables were selected through a univariate analysis. Subsequently, the predictive performance of seven models (XGBoost, LightGBM, CatBoost, GBDT, ANN, TabNet, and DT) was compared. The algorithm that demonstrated optimal performance was chosen to establish the dose prediction model. Model validation used confusion matrices and ROC analysis. Additionally, a dose subgroup analysis was conducted.

RESULTS

A total of 298 patients were included. TabNet was selected to establish the venlafaxine dose prediction model, which exhibited the highest performance with an accuracy of 0.80. The analysis identified seven crucial variables correlated with venlafaxine daily dose, including blood venlafaxine concentration, total protein, lymphocytes, age, globulin, cholinesterase, and blood platelet count. The area under the curve (AUC) for predicting venlafaxine doses of 75 mg, 150 mg, and 225 mg were 0.90, 0.85, and 0.90, respectively.

CONCLUSION

We successfully developed a TabNet model to predict venlafaxine doses using real-world data. This model demonstrated substantial predictive accuracy, offering a personalized dosing regimen for venlafaxine. These findings provide valuable guidance for the clinical use of the drug.

Long-acting antipsychotic treatments: focus on women with schizophrenia

Effective management of schizophrenia (SZ) requires long-term treatment with antipsychotics (APs) to prevent clinical relapse, attain remission and improve patients' personal and social functioning, and quality of life. Although APs remain the cornerstone treatment for patients with SZ, despite their potential benefits, long-acting injectable APs (LAI-APs) remain underused, most notably in women with SZ. The efficacy and tolerability of APs differ significantly between men and women, and some of these differences are more noticeable depending on the patient's age and the stage of the disorder. Although sex differences may influence treatment outcomes in SZ, their pertinence has been insufficiently addressed, especially regarding the use of LAI-APs. Some biological and social experiences, such as pregnancy, lactation, contraception and menopause, are specific to women, but these remain under-researched issues. Implications of this disorder in parenting are also of special pertinence regarding women; therefore, taking sex differences into account when treating SZ patients is now recommended, and improving personalized approaches has been proposed as a priority in the management of psychosis. In this narrative, critical review, we address some aspects specific to sex and their implications for the clinical management of women with SZ, with a special focus on the potential role of LAI-AP treatments.

Therapeutic Drug Monitoring of Olanzapine: Effects of Clinical Factors on Plasma Concentrations in Psychiatric Patients

BACKGROUND

Therapeutic drug monitoring (TDM) is strongly recommended for olanzapine due to its high pharmacokinetic variability. This study aimed to investigate the impact of various clinical factors on olanzapine plasma concentrations in patients with psychiatric disorders.

METHODS

The study used TDM data from the PsyMetab cohort, including 547 daily dose-normalized, steady-state, olanzapine plasma concentrations (C:D ratios) from 248 patients. Both intrinsic factors (eg, sex, age, body weight) and extrinsic factors (eg, smoking status, comedications, hospitalization) were examined. Univariate and multivariable, linear, mixed-effects models were employed, with a stepwise selection procedure based on Akaike information criterion to identify the relevant covariates.

RESULTS

In the multivariable model (based on 440 observations with a complete data set), several significant findings emerged. Olanzapine C:D ratios were significantly lower in smokers (β = -0.65, P < 0.001), valproate users (β = -0.53, P = 0.002), and inpatients (β = -0.20, P = 0.025). Furthermore, the C:D ratios decreased significantly as the time since the last dose increased (β = -0.040, P < 0.001). The male sex had a significant main effect on olanzapine C:D ratios (β = -2.80, P < 0.001), with significant interactions with age (β = 0.025, P < 0.001) and body weight (β = 0.017, P = 0.011). The selected covariates explained 30.3% of the variation in C:D ratios, with smoking status accounting for 7.7% and sex contributing 6.9%. The overall variation explained by both the fixed and random parts of the model was 67.4%. The model facilitated the prediction of olanzapine C:D ratios based on sex, age, and body weight.

CONCLUSIONS

The clinical factors examined in this study, including sex, age, body weight, smoking status, and valproate comedication, remarkably influence olanzapine C:D ratios. Considering these factors, in addition to TDM and the clinical situation, could be important for dose adjustment.

Rapid Metabolism Underlying Subtherapeutic Serum Levels of Atypical Antipsychotics Preceding Clozapine Treatment: A Retrospective Analysis of Real-World Data

INTRODUCTION

Adequate antipsychotic treatment intensity is required before diagnosing resistant schizophrenia and initiating clozapine treatment. We aimed to investigate potential rapid drug metabolism underlying low dose-adjusted serum concentration (CD) of non-clozapine atypical antipsychotics preceding clozapine treatment.

METHODS

Patients using non-clozapine, atypical antipsychotics (aripiprazole, risperidone, olanzapine, or quetiapine) within 1 year before starting clozapine were included in this study from a therapeutic drug monitoring service in Oslo, Norway, between 2005 and 2023. Patients were assigned into low CD (LCD) and normal CD (NCD) subgroups. Using a reference sample with 147,964 antipsychotic measurements, LCD was defined as CDs below the 25th percentile, while patients with NCD exhibited CDs between the 25th and 75th percentile of the respective reference measurements. Metabolic ratios, doses, and frequency of subtherapeutic levels of non-clozapine antipsychotics were compared between LCD and NCD groups.

RESULTS

Preceding clozapine treatment, 110 out of 272 included patients (40.4%) were identified with LCD. Compared with the NCD group, LCD patients exhibited higher metabolic ratios of olanzapine (1.5-fold; p < 0.001), quetiapine (3.0-fold; p < 0.001), and risperidone (6.0-fold; p < 0.001). Metabolic ratio differences were independent of smoking and CYP2D6 genotype for olanzapine (p = 0.008) and risperidone (p = 0.016), respectively. Despite higher doses of olanzapine (1.25-fold; p = 0.054) and quetiapine (1.6-fold; p = 0.001) in LCD versus NCD patients, faster metabolism among the former was accompanied by higher frequencies of subtherapeutic levels of olanzapine (3.3-fold; p = 0.044) and quetiapine (1.8-fold; p = 0.005).

CONCLUSION

LCD and associated rapid metabolism of non-clozapine antipsychotics is frequent before starting clozapine treatment. For olanzapine and quetiapine, this is associated with significantly increased risk of having subtherapeutic concentrations.

Sex differences in effectiveness and adverse effects of mood stabilizers and antipsychotics: A systematic review

BACKGROUND

Psychiatric disorders differ in their prevalence, symptom profiles, and disease courses in men and women. However, sex differences in psychiatric disorders have not received enough attention to guide treatment recommendations. This systematic review aims to summarize sex differences in the treatment responses and adverse effects of mood stabilizers and antipsychotics transdiagnostically.

METHODS

We conducted a systematic review following the PRISMA 2020 statement (CRD42020212478). A literature search was conducted using MEDLINE, Embase, Cochrane Central, PsycINFO, Web of Science Core Collection, and Scopus databases. Studies comparing mood stabilizer or antipsychotic treatment outcomes in men and women were included. JBI critical appraisal checklists were used to assess bias risk.

RESULTS

Out of 4866 records, 129 reports (14 on mood stabilizers, 115 on antipsychotics) with varying designs were included. Sample sizes ranged from 17 to 22,774 participants (median = 147). The most common psychiatric diagnoses were schizophrenia spectrum (n = 109, 84.5 %) and bipolar disorders (n = 38, 29.5 %). Only four studies explored sex differences in mood stabilizer treatment response. In 40 articles on antipsychotic treatment response, 18 indicated no sex difference, while 16 showed females had better outcomes. Women had more adverse effects with both mood stabilizers and antipsychotics. The risk of bias was low in 84 (65.1 %) of studies.

LIMITATIONS

Substantial heterogeneity among the studies precluded performing a meta-analysis.

CONCLUSION

Number of studies focusing on sex differences in treatment outcomes of mood stabilizers is limited. Women may respond better to antipsychotics than men, but also experience more side effects. The impact of pharmacokinetics on sex differences warrants more attention.

Validation of Population Pharmacokinetic Models for Clozapine Dosage Prediction

BACKGROUND

Clozapine is unique in its capacity to ameliorate severe schizophrenia but at high risk of toxicity. A relationship between blood concentration and clinical response and evidence for concentration-response relationships to some adverse effects justify therapeutic drug monitoring of clozapine. However, the relationship between drug dose and blood concentration is quite variable. This variability is, in part, due to inductive and inhibitory interactions varying the activity of cytochrome P450 1A2 (CYP1A2), the principal pathway for clozapine elimination. Several population pharmacokinetic models have been presented to facilitate dose selection and to identify poor adherence in individual patients. These models have faced little testing for validity in independent populations or even for persisting validity in the source population.

METHODS

Therefore, we collected a large population of clozapine-treated patients (127 patients, 1048 timed plasma concentrations) in whom dosing and covariate information could be obtained with high certainty. A population pharmacokinetic model was constructed with data collected in the first 6 weeks from study enrolment (448 plasma concentrations), to estimate covariate influences and to allow alignment with previously published models. The model was tested for its performance in predicting the concentrations observed at later time intervals up to 5 years. The predictive performances of 6 published clozapine population models were then assessed in the entire population.

RESULTS

The population pharmacokinetic model based on the first 6 weeks identified significant influences of sex, smoking, and cotreatment with fluvoxamine on clozapine clearance. The model built from the first 6 weeks had acceptable predictive performance in the same patient population up to the first 26 weeks using individual parameters, with a median predictive error (PE) of -0.1% to -15.9% and median absolute PE of 22.9%-27.1%. Predictive performance fell progressively with time after 26 weeks. Bayesian addition of plasma concentration observations within each prediction period improved individual predictions. Three additional observations extended acceptable predictive performance into the second 6 months of therapy. When the published models were tested with the entire data set, median PE ranged from -8% to +35% with a median absolute PE of >39% in all models. Thus, none of the tested models was successful in external validation. Bayesian addition of single patient observations improved individual predictions from all models but still without achieving acceptable performances.

CONCLUSIONS

We conclude that the relationship between covariates and blood clozapine concentrations differs between populations and that relationships are not stable over time within a population. Current population models for clozapine are not capturing influential covariates.

Therapeutic Drug Level Monitoring of Antipsychotics at an Inpatient Psychiatric Hospital

BACKGROUND

The American Psychiatric Association guidelines for the treatment of patients with schizophrenia state that the utility of antipsychotic therapeutic drug monitoring (TDM) remains unclear, except for clozapine or assessing adherence. The aim of this study was to investigate the extent and impact of antipsychotic TDM in inpatient practice to improve its utilization.

METHODS

Patients with antipsychotic blood levels drawn between May 1, 2021 and January 31, 2023 were invited to consent for retrospective chart data analysis to determine the influence of antipsychotic blood levels on their treatment. Approximately 42% of patients consented. Data collected from the patients' electronic medical records included age, ethnicity, race, sex, diagnosis, comorbidities, adverse drug reactions, medications, doses and frequency, antipsychotics and levels, laboratory values, and treatment history. Comparisons were made between antipsychotic levels that were within and outside the therapeutic range and the status of antipsychotic regimen adjustments.

RESULTS

A total of 135 antipsychotic levels from 40 inpatients were analyzed. Approximately 48% of the levels were appropriately drawn, whereas 52% were inappropriately drawn. Clozapine had the highest TDM rate (59%) and the most common diagnoses were schizophrenia (45%) and schizoaffective disorder (32.5%). More levels were appropriately drawn for clozapine (47.3% versus 24.3%) than for risperidone (41% versus 46.2%). Appropriately drawn clozapine levels correlated with higher daily doses and levels at or above the therapeutic threshold of 350 ng/mL.

CONCLUSIONS

Most antipsychotic drug levels were inappropriately drawn, emphasizing the complexity and potential for errors in TDM. Although more patients were prescribed risperidone, clozapine had the highest TDM rate. Clinicians were more likely to keep antipsychotic regimens unchanged for appropriately drawn levels and adjust doses for inappropriately drawn levels.

Clinical and pharmacological factors influencing serum clozapine and norclozapine levels

Background

Clozapine (CLO) is a very effective antipsychotic, whose use is associated with dose-dependent risk of complications. Due to high interindividual variability in CLO metabolism, there is a need to identify factors affecting the blood concentrations of CLO and its active metabolite, norclozapine (NCLO).

Methods

A total of 446 blood samples (collected from 233 women and 213 men, aged from 18 to 77 years) were included in this study and analyzed for CLO and NCLO concentrations. The patients were treated at a psychiatric hospital in Warsaw in the years 2016-2021. Serum CLO and NCLO concentrations were determined with high-performance liquid chromatography coupled to UV.

Results

The following factors were shown to increase serum CLO and NCLO levels: higher CLO dose (p < 0.001), female sex (p < 0.001), nonsmoker status (p < 0.001), the use of more than two additional psychotropic drugs (only in the case of CLO; p = 0.046), concomitant use of beta-blockers (for CLO p = 0.049; for NCLO p < 0.001), and older age (for CLO p < 0.001; for NCLO p = 0.011). Despite the use of CLO at daily doses within the recommended range (200-450 mg), the evaluated serum CLO and NCLO levels were within the therapeutic ranges in only 37% and 75% of cases, respectively, with 5.6% of cases exceeding the CLO toxicity threshold.

Discussion

The use of CLO at recommended doses does not guarantee achieving therapeutic concentrations of CLO or NCLO. Women and nonsmokers were at the highest risk of having toxic CLO levels.

Exploring sex differences: insights into gene expression, neuroanatomy, neurochemistry, cognition, and pathology

Increased knowledge about sex differences is important for development of individualized treatments against many diseases as well as understanding behavioral and pathological differences. This review summarizes sex chromosome effects on gene expression, epigenetics, and hormones in relation to the brain. We explore neuroanatomy, neurochemistry, cognition, and brain pathology aiming to explain the current state of the art. While some domains exhibit strong differences, others reveal subtle differences whose overall significance warrants clarification. We hope that the current review increases awareness and serves as a basis for the planning of future studies that consider both sexes equally regarding similarities and differences.

Vaccination and clozapine use: a systematic review and an analysis of the VAERS database

In the context of COVID-19 concerns related to the potential interactions between clozapine and vaccination arose. With the ultimate goal of deriving recommendations for clinical practice, we systematically reviewed the current evidence regarding altered vaccine effectiveness in clozapine-treated patients and safety aspects of vaccination, such as haematological changes and the impact of vaccines on clozapine blood levels, in clozapine-treated patients. A systematic PRISMA-conform literature search of four databases (PubMed, PsycINFO, EMBASE and Cochrane Library) complemented by a case-by-case analysis of the Vaccine Adverse Event Reporting System (VAERS) database was performed. We then systematically appraised the joint evidence and tried to derive recommendations for clinical practice. 14 records were included in this analysis. These records consisted of 5 original articles and 9 case reports. Among the original articles, two studies provided data on the association between clozapine use and antibody responses to vaccination, both indicating that clozapine use in schizophrenia may be associated with reduced levels of immunoglobulins. Additionally, three studies examined vaccine safety in clozapine-treated patients, with no clinically significant adverse effects directly attributable to the interplay between vaccinations and clozapine. VAERS Analysis encompassed 137 reports and showed no consistent evidence of an increased risk for clozapine blood level increases or adverse events. We found no evidence indicating that clozapine impairs the effectiveness of vaccines. Moreover, no serious safety concerns seem to apply when patients on clozapine are receiving vaccines. However, it is crucial to acknowledge that data on the interaction between clozapine and vaccines remain limited.

Factors influencing concentrations of risperidone and 9-hydroxyrisperidone in psychiatric outpatients taking immediate-release formulations of risperidone

OBJECTIVES

To analyze the factors affecting the concentrations of the active moiety of risperidone (RIS) and its active metabolite 9-hydroxyrisperidone (9-OH-RIS) in psychiatric outpatients taking immediate-release formulations.

METHODS

This is a retrospective study on the therapeutic drug monitoring (TDM) data regarding RIS and 9-OH-RIS in adult psychiatric outpatients. TDM data with simultaneous RIS and 9-OH-RIS monitoring from March 2018 to February 2020 and relevant medical records (including dosage, dosage form, sex, age, diagnosis, combined medication, and comorbid disease) from 399 adult psychiatric outpatients (223 males and 176 females) were included in this study.

RESULTS

The daily dose of RIS was 5.56 ± 2.05 mg, the concentration of total active moiety was 42.35 ± 25.46 ng/mL, and the dose-adjusted plasma concentration (C/D) of active moiety was 7.83 ± 3.87 (ng/ml)/(mg/day). Dose, sex, and age were identified as important factors influencing concentrations of RIS and 9-OH-RIS in adult psychiatric outpatients.

CONCLUSIONS

Individualized medication adjustments should be made according to the specific conditions of psychiatric outpatients. The findings strongly support the use of TDM to guide dosing decisions in psychiatric outpatients taking RIS.

No gender differences in the pharmacological emergency treatment of schizophrenia: results of a 21-year observation

Patients suffering from schizophrenia are at high risk for admission and treatment in locked units. This study investigated gender differences in the pharmacological emergency treatment of schizophrenia patients over a 21-year observation period. The current retrospective study was conducted at the Division of Psychiatry I of the Medical University Innsbruck. All adult patients (n = 845; 425 female) suffering from schizophrenia who were admitted involuntarily to one of the acute psychiatric units in the years 1997, 2002, 2007, 2012 and 2017 were included in the study. In the years mentioned above, 590 schizophrenia patients (297 men, 293 women) admitted to a locked unit received pharmacological emergency treatment. With the exception of clozapine which was more frequently administered to men no significant differences between men and women were found in terms of the choice, dosage, and type of application of medication (antipsychotics and benzodiazepines). Since most treatment guidelines for schizophrenia do not consider gender differences at all, it is not surprising that acute treatment is almost the same for men and women. However, in times when individualized therapies gain more and more importance, the consideration of sex differences should be part of new treatment concepts.

Therapeutic drug monitoring of perospirone: The lowest effective plasma concentration in patients with schizophrenia

OBJECTIVES

This study investigated the effects of demographic factors such as age, sex and comedications on the plasma concentrations of perospirone in individuals diagnosed with schizophrenia. Additionally, the relationship between these plasma levels and the clinical efficacy of the medication was explored.

METHODS

Data regarding the plasma concentration of perospirone in patients with schizophrenia were obtained from the Xi'an Mental Health Center and were retrospectively analysed.

RESULTS

The study results revealed a range of 0.50-1.59 ng/mL for the 25th-75th percentile of perospirone concentration in the plasma, which ranged from 0.07 to 6.0 ng/mL. The plasma concentration of perospirone increased with the daily oral dose (r = 0.283, P < 0.05). Furthermore, patients with higher plasma perospirone concentrations and concentration-to-dose ratios (C/D) tended to be older or were women. Notably, the coadministration of valproate significantly reduced perospirone concentration and the C/D ratio by 54.7% and 35.3%, respectively (P < 0.01). Receiver operating characteristics curve analyses revealed that patients exhibited a good clinical response when their plasma perospirone concentrations were ≥ 1.17 ng/mL.

CONCLUSION

The findings suggest that therapeutic drug monitoring of perospirone and adjustments to achieve steady-state concentrations of ≥ 1.17 ng/mL can be beneficial for optimising treatment for patients with schizophrenia.

Impact of age, sex and cytochrome P450 genotype on quetiapine and N-desalkylquetiapine serum concentrations: A study based on real-world data from 8118 patients

AIMS

To investigate the effect of aging, sex and cytochrome P450 (CYP) genotypes on the exposure of quetiapine (QUE) and the pharmacologically active metabolite N-desalkylquetiapine (NDQ).

METHODS

Patients with serum concentrations of QUE and NDQ were included retrospectively from a therapeutic drug monitoring service. The outcome measures were concentration:dose (C:D) ratios of QUE and NDQ, and NDQ:QUE metabolic ratio. Linear mixed model analyses were used to evaluate the effects of age, sex and, subsequently, CYP2D6/3A genotypes.

RESULTS

The average age of the included population (n = 8118 patients) was 44 years (13.5% ≥65 years). The C:D ratio of QUE and NDQ gradually increased in patients aged >50 years compared to those aged 18-30 years, with 28 and 29% increase, respectively, for patients aged >70 years (P < .001). Compared to males, females had 15% lower QUE C:D ratio and 10% higher C:D ratio of NDQ (both P < .001). The NDQ:QUE metabolic ratio was 30% higher in females than in males (P < .001). For females ≥65 years, the NDQ C:D ratio was 36% higher compared to males <65 years (P < .001). A significantly higher NDQ C:D ratio was observed for CYP2D6 intermediate (+7%, P = .012) and poor (+17%, P = .001) compared to normal metabolizers. No effects of CYP3A4*22 and CYP3A5*1 allele variants were observed.

CONCLUSION

This study shows an increase of the QUE and NDQ exposures during aging. Old age, female sex and CYP2D6 allele variants encoding reduced activity are factors associated with high NDQ exposure. Therefore, females ≥65 years carrying CYP2D6 allele variants encoding reduced activity have the highest risk of dose-dependent side effects of NDQ during QUE treatment.

Evidence-Based Recommendations for the Pharmacological Treatment of Women with Schizophrenia Spectrum Disorders

PURPOSE OF REVIEW

Despite clear evidence that sex differences largely impact the efficacy and tolerability of antipsychotic medication, current treatment guidelines for schizophrenia spectrum disorders (SSD) do not differentiate between men and women. This review summarizes the available evidence on strategies that may improve pharmacotherapy for women and provides evidence-based recommendations to optimize treatment for women with schizophrenia.

RECENT FINDINGS

We systematically searched PubMed and Embase for peer-reviewed studies on three topics: (1) sex differences in dose-adjusted antipsychotic serum concentrations, (2) hormonal augmentation therapy with estrogen and estrogen-like compounds to improve symptom severity, and (3) strategies to reduce antipsychotic-induced hyperprolactinemia. Based on three database studies and one RCT, we found higher dose-adjusted concentrations in women compared to men for most antipsychotics. For quetiapine, higher concentrations were specifically found in older women. Based on two recent meta-analyses, both estrogen and raloxifene improved overall symptomatology. Most consistent findings were found for raloxifene augmentation in postmenopausal women. No studies evaluated the effects of estrogenic contraceptives on symptoms. Based on two meta-analyses and one RCT, adjunctive aripiprazole was the best-studied and safest strategy for lowering antipsychotic-induced hyperprolactinemia. Evidence-based recommendations for female-specific pharmacotherapy for SSD consist of (1) female-specific dosing for antipsychotics (guided by therapeutic drug monitoring), (2) hormonal replacement with raloxifene in postmenopausal women, and (3) aripiprazole addition as best evidenced option in case of antipsychotic-induced hyperprolactinemia. Combining these strategies could reduce side effects and improve outcome of women with SSD, which should be confirmed in future longitudinal RCTs.

Association of clozapine and norclozapine levels with patient and therapy characteristics-focus on interaction with valproic acid

PURPOSE

The goal of the study was to examine clozapine (CLZ) and norclozapine (NCLZ) therapeutic drug monitoring (TDM) data and associated sources of pharmacokinetic variability, particularly the impact of valproic acid (VPA) use.

METHODS

This study included 126 patients with psychiatric disorders on mono- or co-therapy with CLZ. Patients' data during routine TDM were collected retrospectively from clinical records. The descriptive and statistical analysis was computed using IBM SPSS Statistics software (version 22, NY, USA). Multiple linear regression, based on the last observations, was used to assess correlation between demographic characteristics, life habits and co-therapy with dose-corrected serum levels (C/D) of CLZ and NCLZ, as well as CLZ/NCLZ.

RESULTS

A total of 295 CLZ concentrations were measured in 126 patients, with a mean of 275.5 ± 174.4 µg/L, while 124 NCLZ concentrations were determined in 74 patients, with a mean of 194.6 ± 149.8 µg/L. A statistically significant effect on ln-transformed CLZ C/D was confirmed for sex and smoking, whereas sex, smoking and VPA therapy were associated with ln-transformed NCLZ C/D. According to the final models, lower values of NCLZ C/D for about 45.9% can be expected in patients receiving VPA. Concomitant use of VPA was the only factor detected to contribute in CLZ/NCLZ variability.

CONCLUSION

The results of this study may help clinicians interpret TDM data and optimize CLZ dosing regimens, especially in patients concomitantly treated with VPA. Our results show that VPA primarily decreases NCLZ levels, while alteration of the parent drug is not statistically significant.

Association of smoking cigarettes, age, and sex with serum concentrations of olanzapine in patients with schizophrenia

Introduction

Olanzapine is an atypical antipsychotic drug which is effective in the treatment of schizophrenia. Cigarette smoking, age, and sex could be related to the pharmacokinetics and serum concentrations of olanzapine in patients with schizophrenia. The aim of the study was to examine whether there was a significant difference in the serum olanzapine concentrations with regard to the mentioned factors.

Materials and methods

A total of 58 outpatients with schizophrenia (37 smokers, 42 men, 35 older than 40 years) participated in the study. Blood was sampled in serum tubes just before taking the next dose of olanzapine. Olanzapine was extracted by liquid-liquid extraction and was measured by an in-house high-performance liquid chromatography method on Shimadzu Prominence HPLC System with diode array detector SPD-M20A (Shimadzu, Kyoto, Japan). The results were expressed as the ratio of concentration to the daily dose of olanzapine (C/D). Non-parametric statistical tests were used to analyse differences between variables.

Results

The median C/D of olanzapine (interquartile range) in smokers was 6.0 (3.4-10.2) nmol/L/mg and in non-smokers 10.1 (5.9-17.6) nmol/L/mg; P = 0.007. The median C/D of olanzapine in patients younger than 40 years was 5.6 (4.5-10.2) nmol/L/mg and in patients older than 40 years 8.4 (5.6-13.0) nmol/L/mg; P = 0.105. The median C/D of olanzapine in male patients was 6.6 (4.6-10.4) nmol/L/mg and in female patients 9.0 (5.9-15.3) nmol/L/mg; P = 0.064.

Conclusions

The serum olanzapine concentration was significantly lower in smoking than in non-smoking patients with schizophrenia. No significant difference was demonstrated with regard to age and sex.

Age, Sex, and Comedication Effects on the Steady-State Plasma Concentrations of Amisulpride in Chinese Patients with Schizophrenia

BACKGROUND

Amisulpride, a second-generation atypical antipsychotic drug, was first marketed in Europe in the 1990s. This study aimed to provide a reference for the clinical application of amisulpride. The effects of age, sex, or specific comedications on amisulpride concentrations in Chinese patients with schizophrenia in the real world were investigated.

METHODS

A retrospective study was conducted of data on amisulpride based on the therapeutic drug monitoring service database at the Zigong Affiliated Hospital of Southwest Medical University.

RESULTS

Based on the inclusion criteria, 195 plasma samples from 173 patients (67.05% female and 32.95% male patients) were included for in-depth analysis. The median daily dose of amisulpride was 400 mg/d, median plasma concentration was 457.50 ng/mL, and median concentration/dose (C/D) ratio was 1.04 ng/mL/mg/d. The daily dose of amisulpride positively correlated with measured steady-state plasma concentrations. A significant difference was observed in the subgroup analysis of the combination with valproic acid, zopiclone, or aripiprazole on plasma concentrations. Combining amisulpride with these drugs increased the C/D ratios by 0.56-, 2.31-, and 0.77-fold, respectively. After adjusting for age, the median C/D ratio was found to be significantly different between female and male patients. However, no significant differences in daily dose, plasma concentration, and C/D ratio were noted with respect to sex and age of the patients.

CONCLUSIONS

Sex differences were inferred for the first time in this study, with differential effects on daily dose, steady-state plasma concentration, and C/D ratio associated with the population. In the included study samples, blood concentrations were distributed in the range of 223.25-823.55 ng/mL, which perhaps needs to be evaluated in line with the reference range of ammonia-sulfur ratios in the Chinese population.

A machine learning model for predicting blood concentration of quetiapine in patients with schizophrenia and depression based on real-world data

AIMS

This study aimed to establish a prediction model of quetiapine concentration in patients with schizophrenia and depression, based on real-world data via machine learning techniques to assist clinical regimen decisions.

METHODS

A total of 650 cases of quetiapine therapeutic drug monitoring (TDM) data from 483 patients at the First Hospital of Hebei Medical University from 1 November 2019 to 31 August 2022 were included in the study. Univariate analysis and sequential forward selection (SFS) were implemented to screen the important variables influencing quetiapine TDM. After 10-fold cross validation, the algorithm with the optimal model performance was selected for predicting quetiapine TDM among nine models. SHapley Additive exPlanation was applied for model interpretation.

RESULTS

Four variables (daily dose of quetiapine, type of mental illness, sex and CYP2D6 competitive substrates) were selected through univariate analysis (P < .05) and SFS to establish the models. The CatBoost algorithm with the best predictive ability (mean [SD] R2  = 0.63 ± 0.02, RMSE = 137.39 ± 10.56, MAE = 103.24 ± 7.23) was chosen for predicting quetiapine TDM among nine models. The mean (SD) accuracy of the predicted TDM within ±30% of the actual TDM was 49.46 ± 3.00%, and that of the recommended therapeutic range (200-750 ng mL-1 ) was 73.54 ± 8.3%. Compared with the PBPK model in a previous study, the CatBoost model shows slightly higher accuracy within ±100% of the actual value.

CONCLUSIONS

This work is the first real-world study to predict the blood concentration of quetiapine in patients with schizophrenia and depression using artificial intelligent techniques, which is of significance and value for clinical medication guidance.

Study on the daily dose and serum concentration of clozapine in psychiatric patients and possible influencing factors of serum concentration

BACKGROUND

Clozapine is the most effective drug for treatment-resistant schizophrenia, and the dosage and concentration of clozapine in the treatment of mental illness vary greatly in different populations and are affected by many factors.

METHODS

The serum clozapine concentration of 3734 psychiatric patients was detected, and data on daily dose, sex, age and other medical records were collected for statistical analysis.

RESULTS

The mean daily dose, mean serum concentration and mean C/D (concentration/dose) ratio of clozapine were 191.02 ± 113.47 mg/day, 326.15 ± 235.66 ng/mL and 1.94 ± 1.25 ng/mL per mg/day, respectively. There was difference in daily dose between sexes, and females had higher daily dose (p <0.01), higher serum clozapine concentrations (p < 0.01) and higher C/D ratios (p < 0.01). There were significant differences in daily dose (p < 0.001), serum drug concentration (p < 0.001) and C/D ratio (p < 0.001) among different age groups. The daily dose decreased with age (p for trend < 0.001), and the C/D ratio increased with age (p for trend < 0.001). Inpatients and outpatients had no difference in daily dose, but inpatients had higher serum concentration (p < 0.001) and C/D ratio (p < 0.001). There was no difference in daily dose among different occupations, but there were significant differences in serum concentration (p < 0.001) and C/D ratio (p < 0.001), and unemployed patients may have higher serum concentration and C/D ratio. Duration of disease, comorbidity, marital status, and psychotic type may influence the daily dose and serum concentration.

CONCLUSIONS

The effective daily dose and serum concentration of clozapine in the study area may be lower than recommended levels, and women have higher serum concentrations and slower metabolic rates. With increasing age, the daily dose decreases, and the metabolic rate slows. Inpatient status and occupation of patients may influence the serum concentration and metabolic rate of clozapine.

Predicting plasma concentration of quetiapine in patients with depression using machine learning techniques based on real-world evidence

OBJECTIVES

We develop a model for predicting quetiapine levels in patients with depression, using machine learning to support decisions on clinical regimens.

METHODS

Inpatients diagnosed with depression at the First Hospital of Hebei Medical University from 1 November 2019, to 31 August were enrolled. The ratio of training cohort to testing cohort was fixed at 80%:20% for the whole dataset. Univariate analysis was executed on all information to screen the important variables influencing quetiapine TDM. The prediction abilities of nine machine learning and deep learning algorithms were compared. The prediction model was created using an algorithm with better model performance, and the model's interpretation was done using the SHapley Additive exPlanation.

RESULTS

There were 333 individuals and 412 cases of quetiapine TDM included in the study. Six significant variables were selected to establish the individualized medication model. A quetiapine concentration prediction model was created through CatBoost. In the testing cohort, the projected TDM's accuracy was 61.45%. The prediction accuracy of quetiapine concentration within the effective range (200-750 ng/mL) was 75.47%.

CONCLUSIONS

This study predicts the plasma concentration of quetiapine in depression patients by machine learning, which is meaningful for the clinical medication guidance.

Effects of quetiapine on sleep: A systematic review and meta-analysis of clinical trials

Quetiapine is a common off-label antipsychotic drug for treating insomnia. Its effects in different disease conditions and dosages remain unclear. We conducted a systematic review and meta-analysis in clinical trials examining the efficacy of low-dose quetiapine in sleep. We obtained 21 clinical trials. Mean difference (MD), standard mean difference (SMD), and odds ratio (OR) were used to estimate the effect sizes using a random-effects model. The pooled results showed that quetiapine improved sleep quality compared with placebo (SMD: -0.57 [95%CI: -0.75, -0.4]). The SMD of sleep quality was correlated with age (coefficient: -0.0174) and sex (coefficient: -0.012). The significant effects were observed in the general anxiety disorder (SMD: -0.59 [95%CI: -0.92, -0.27]), major depressive disorder (SMD: -0.47 [95%CI: -0.66, -0.28]), and healthy (SMD: -1.33, [95%CI [-2.12, -0.54]) subgroups, at the dosage of 50 mg (SMD: -0.36 [95%CI: -0.36, -0.11]), 150 mg (SMD: -0.4 [95%CI: -0.52, -0.29]), and 300 mg (SMD: -0.17 [95%CI: -0.31,-0.04]). Quetiapine increased total sleep time compared with placebo (MD: 47.91 [95%CI: 28.06, 67.76]) but not when compared with other psychiatric drugs (MD: -4.19 [95%CI: -19.43, 11.05]). Adverse events (AEs) and discontinuation due to AEs were common among the quetiapine users. Quetiapine is effective as a sleep-helping drug. Precaution is suggested when interpreting the results on the elderly due to the high heterogeneity caused by incorporating patients over 66 years in the meta-analyses. We recommend an initial dosage of 50-150 mg/day with priority consideration for the elderly with GAD or MDD while monitoring its potential AEs.

Joint population pharmacokinetic modeling of venlafaxine and O-desmethyl venlafaxine in healthy volunteers and patients to evaluate the impact of morbidity and concomitant medication

Introduction: Venlafaxine (VEN) is a widely used dual selective serotonin/noradrenaline reuptake inhibitor indicated for depression and anxiety. It undergoes first-pass metabolism to its active metabolite, O-desmethyl venlafaxine (ODV). The aim of the present study was to develop a joint population pharmacokinetic (PPK) model to characterize their pharmacokinetic characters simultaneously. Methods: Plasma concentrations with demographic and clinical data were derived from a bioequivalence study in 24 healthy subjects and a naturalistic TDM setting containing 127 psychiatric patients. A parent-metabolite PPK modeling was performed with NONMEM software using a non-linear mixed effect modeling approach. Goodness of fit plots and normalized prediction distribution error method were used for model validation. Results and conclusion: Concentrations of VEN and ODV were well described with a one-compartment model incorporating first-pass metabolism. The first-pass metabolism was modeled as a first-order conversion. The morbid state and concomitant amisulpride were identified as two significant covariates affecting the clearance of VEN and ODV, which may account for some of the variations in exposure. This model may contribute to the precision medication in clinical practice and may inspire other drugs with pre-system metabolism.

Current Status of Therapeutic Drug Monitoring in Mental Health Treatment: A Review

Therapeutic drug monitoring (TDM) receives growing interest in different psychiatric clinical settings (emergency, inpatient, and outpatient services). Despite its usefulness, TDM remains underemployed in mental health. This is partly due to the need for evidence about the relationship between drug serum concentration and efficacy and tolerability, both in the general population and even more in subpopulations with atypical pharmacokinetics. This work aims at reviewing the scientific literature published after 2017, when the most recent guidelines about the use of TDM in mental health were written. We found 164 pertinent records that we included in the review. Some promising studies highlighted the possibility of correlating early drug serum concentration and clinical efficacy and safety, especially for antipsychotics, potentially enabling clinicians to make decisions on early laboratory findings and not proceeding by trial and error. About populations with pharmacokinetic peculiarities, the latest studies confirmed very common alterations in drug blood levels in pregnant women, generally with a progressive decrease over pregnancy and a very relevant dose-adjusted concentration increase in the elderly. For adolescents also, several drugs result in having different dose-related concentration values compared to adults. These findings stress the recommendation to use TDM in these populations to ensure a safe and effective treatment. Moreover, the integration of TDM with pharmacogenetic analyses may allow clinicians to adopt precise treatments, addressing therapy on an individual pharmacometabolic basis. Mini-invasive TDM procedures that may be easily performed at home or in a point-of-care are very promising and may represent a turning point toward an extensive real-world TDM application. Although the highlighted recent evidence, research efforts have to be carried on: further studies, especially prospective and fixed-dose, are needed to replicate present findings and provide clearer knowledge on relationships between dose, serum concentration, and efficacy/safety.

Effects of Age, Sex, and Comedication on the Plasma Concentrations of Olanzapine in Chinese Patients With Schizophrenia Based on Therapeutic Drug Monitoring Data

BACKGROUND

Olanzapine (OLA) is an atypical second-generation antipsychotic that exhibits significant pharmacokinetic variability. We retrospectively investigated the effects of age, sex, and specific comedications on OLA pharmacokinetics in Chinese patients with schizophrenia.

METHODS

Data on sex, age, and OLA dosage and steady-state plasma concentrations of 386 patients with schizophrenia (who have received OLA or a comedication of OLA with a psychotherapeutic drug) were collected and analyzed. The combined effects of dosage, age, sex, and comedication on OLA plasma levels were assessed via multiple linear regression analyses.

RESULTS

A daily dose of OLA was positively correlated with the drug's plasma concentrations. Overall, the OLA plasma concentrations and concentration-to-dose ratio (C/D) of the studied patients varied by 53.6- and 64.1-fold, achieving median values of 42.7 ng/mL and 2.73 (ng/mL)/(mg/d), respectively. Furthermore, a 1.27-fold higher estimated C/D in patients 60 years or older than in those younger than 60 years was identified. Female patients demonstrated a 33.6% higher C/D than in male patients. When coadministered with mood stabilizers (valproate or lithium), the median OLA C/D was 24.1% to 26.1% lower than that of OLA monotherapy. Interestingly, the OLA plasma concentration and C/D were not significantly affected by a comedication with aripiprazole, haloperidol, amisulpride, risperidone, clozapine, ziprasidone, citalopram, or buspirone.

CONCLUSIONS

The administered drug's dose was identified as an important determinant of the achieved OLA plasma concentration, with a positive correlation. The patients' sex and valproate (or lithium) comedication can significantly affect the C/D of OLA. Therapeutic drug monitoring should be routinely applied in cases of OLA-receiving patients with schizophrenia.

Women with Schizophrenia-Spectrum Disorders After Menopause: A Vulnerable Group for Relapse

BACKGROUND AND HYPOTHESIS

Throughout the life stages of women with schizophrenia-spectrum disorders (SSD), lower estrogen levels are associated with more severe disease course. At perimenopause in the mid-forties, estrogen levels decline to remain persistently low after menopause. This period is hypothesized to increase relapse risk and reduce antipsychotic effectiveness in preventing relapse.

STUDY DESIGN

The cohort of persons with schizophrenia/schizoaffective disorder was identified from Finnish nationwide registers (N = 61 889) and stratified by sex and age <45 vs. ≥45 years. Hospitalizations for psychosis were defined per 5-year age group during the follow-up 1996-2017. Risk of psychosis hospitalization (Adjusted Hazard Ratio, aHR) was assessed using within-individual design, by comparing antipsychotic monotherapy use to nonuse periods in the same individuals for seven dose categories in defined daily doses (DDDs/day).

RESULTS

Starting at age 45-50, women were consistently more often hospitalized for psychosis than their male peers. Women ≥45 had significantly higher aHRs than women <45 at antipsychotic monotherapy >0.6 DDDs/day, and than men at >1.1 DDDs/day. This female-specific age-dependent decrease in effectiveness was present for clozapine doses >0.6 DDDs/day, olanzapine doses >1.4 DDDs/day, and for specific doses of quetiapine (0.9-1.1 DDDs/day) and risperidone (0.6-0.9 DDDs/day).

CONCLUSIONS

While younger women have a lower risk of relapse and generally need a lower antipsychotic dose to prevent rehospitalization than men, antipsychotic effectiveness declines in women after the age of 45. Starting in mid-forties, older women with SSD should be regarded as a vulnerable group that deserve special attention.

The Effect of Menopause on Antipsychotic Response

Background: It has been hypothesized that, whenever estrogen levels decline, psychosis symptoms in women increase. At menopause, this can happen in two main ways: (a) the loss of estrogen (mainly estradiol) can directly affect central neurotransmission, leading to increase in schizophrenia-related symptoms, and (b) the loss of estrogen can decrease the synthesis of enzymes that metabolize antipsychotic drugs, thus weakening their efficacy. Aims and Methods: The aim of this narrative review was to investigate the second possibility by searching PubMed and ClinicalTrials.gov for studies over the last two decades that investigated the metabolism of antipsychotics and their efficacy before and after menopause in women or that studied systemic and local estrogen level effects on the pharmacokinetics and pharmacodynamics of individual antipsychotic drugs. Results: The evidence suggests that symptom level in women with schizophrenia rises after menopause for many reasons beyond hormones but, importantly, there is an estrogen-dependent loss of efficacy related to antipsychotic treatment. Conclusion: Effective clinical intervention is challenging; nevertheless, several promising routes forward are suggested.

An interpretable stacking ensemble learning framework based on multi-dimensional data for real-time prediction of drug concentration: The example of olanzapine

Background and Aim: Therapeutic drug monitoring (TDM) has evolved over the years as an important tool for personalized medicine. Nevertheless, some limitations are associated with traditional TDM. Emerging data-driven model forecasting [e.g., through machine learning (ML)-based approaches] has been used for individualized therapy. This study proposes an interpretable stacking-based ML framework to predict concentrations in real time after olanzapine (OLZ) treatment.

Methods: The TDM-OLZ dataset, consisting of 2,142 OLZ measurements and 472 features, was formed by collecting electronic health records during the TDM of 927 patients who had received OLZ treatment. We compared the performance of ML algorithms by using 10-fold cross-validation and the mean absolute error (MAE). The optimal subset of features was analyzed by a random forest-based sequential forward feature selection method in the context of the top five heterogeneous regressors as base models to develop a stacked ensemble regressor, which was then optimized via the grid search method. Its predictions were explained by using local interpretable model-agnostic explanations (LIME) and partial dependence plots (PDPs).

Results: A state-of-the-art stacking ensemble learning framework that integrates optimized extra trees, XGBoost, random forest, bagging, and gradient-boosting regressors was developed for nine selected features [i.e., daily dose (OLZ), gender_male, age, valproic acid_yes, ALT, K, BW, MONO#, and time of blood sampling after first administration]. It outperformed other base regressors that were considered, with an MAE of 0.064, R-square value of 0.5355, mean squared error of 0.0089, mean relative error of 13%, and ideal rate (the percentages of predicted TDM within ± 30% of actual TDM) of 63.40%. Predictions at the individual level were illustrated by LIME plots, whereas the global interpretation of associations between features and outcomes was illustrated by PDPs.

Conclusion: This study highlights the feasibility of the real-time estimation of drug concentrations by using stacking-based ML strategies without losing interpretability, thus facilitating model-informed precision dosing.

Comparison of serum and whole blood concentrations in quetiapine overdose cases

This study aimed to compare whole blood and serum concentrations of quetiapine in acute poisoning cases. Authentic whole blood and respective serum samples were routinely collected from patients diagnosed with blood poisoning at our University Hospital. Accordingly, whole blood and serum paired samples from nine patients (one male and eight female patients) were analyzed for quetiapine using liquid chromatography-mass spectrometry (LC-MS). Quetiapine concentrations in whole blood and serum samples ranged widely from 5.4 to 2780 ng/mL and 9.9 to 2500 ng/mL, respectively. The whole blood/serum concentration ratio was 0.5-1.1 and increased together with an increase in whole blood and serum quetiapine concentrations. The ratio was reversed at around 2500 ng/mL to > 1. Our findings suggest that whole blood concentrations are more useful than serum concentrations in diagnosing quetiapine poisonings.

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.

Towards better care for women with schizophrenia-spectrum disorders

Women with a schizophrenia-spectrum disorder (SSD) have a better clinical profile than do men at the start of their illness but progress to the same state within the first few years of living with SSD. There are benefits to be gained across different areas in the care currently offered to women with psychosis. An important point for improvement is the early detection of female-specific signs of a first episode of psychosis, to shorten the duration of untreated psychosis, with prompt access to early intervention services. Special attention should be paid to sexual health, and to any history of childhood trauma. Antipsychotics require dosing and prescription tailored to the female physiology that consider hormonal life phases such as menopause. Switching to prolactin-sparing medications can benefit both mental and somatic health. Finally, hormone replacement therapy should be considered for postmenopausal women. By providing female-specific care, women with schizophrenia-spectrum disorders will have optimal chances to fare well.

Therapeutic drug monitoring in children and adolescents with schizophrenia and other psychotic disorders using risperidone

Risperidone is commonly used to treat different psychiatric disorders worldwide. Knowledge on dose–concentration relationships of risperidone treatment in children and adolescents with schizophrenia or other psychotic disorders is, however, scarce and no age-specific therapeutic ranges have been established yet. Multicenter data of a therapeutic drug monitoring service were analyzed to evaluate the relationship between risperidone dose and serum concentration of the active moiety (risperidone (RIS) plus its main metabolite 9-hydroxyrisperidone (9-OH-RIS)) in children and adolescents with psychotic disorders. Patient characteristics, doses, serum concentrations and therapeutic outcomes were assessed by standardized measures. The study also aimed to evaluate whether the therapeutic reference range for adults (20–60 ng/ml) is applicable for minors. In the 64 patients (aged 11–18 years) included, a positive correlation between daily dose and the active moiety (RIS_am) concentration was found (r_s = 0.49, p = 0.001) with variation in dose explaining 24% (r_s² = 0.240) of the variability in serum concentrations. While the RIS_am concentration showed no difference, RIS as well 9-OH-RIS concentrations and the parent to metabolite ratio varied significantly in patients with co-medication of a CYP2D6 inhibitor. Patients with extrapyramidal symptoms (EPS) had on average higher RISam concentrations than patients without (p = 0.05). Considering EPS, the upper threshold of the therapeutic range of RIS_am was determined to be 33 ng/ml. A rough estimation method also indicated a possibly decreased lower limit of the preliminary therapeutic range in minors compared to adults. These preliminary data may contribute to the definition of a therapeutic window in children and adolescents with schizophrenic disorders treated with risperidone. TDM is recommended in this vulnerable population to prevent concentration-related adverse drug reactions.

Antipsychotic medication for women with schizophrenia spectrum disorders

There are significant differences between men and women in the efficacy and tolerability of antipsychotic drugs. Here, we provide a comprehensive overview of what is currently known about the pharmacokinetics and pharmacodynamics of antipsychotics in women with schizophrenia spectrum disorders (SSDs) and translate these insights into considerations for clinical practice. Slower drug absorption, metabolism and excretion in women all lead to higher plasma levels, which increase the risk for side-effects. Moreover, women reach higher dopamine receptor occupancy compared to men at similar serum levels, since oestrogens increase dopamine sensitivity. As current treatment guidelines are based on studies predominantly conducted in men, women are likely to be overmedicated by default. The risk of overmedicating generally increases when sex hormone levels are high (e.g. during ovulation and gestation), whereas higher doses may be required during low-hormonal phases (e.g. during menstruation and menopause). For premenopausal women, with the exceptions of quetiapine and lurasidone, doses of antipsychotics should be lower with largest adjustments required for olanzapine. Clinicians should be wary of side-effects that are particularly harmful in women, such as hyperprolactinaemia which can cause oestrogen deficiency and metabolic symptoms that may cause cardiovascular diseases. Given the protective effects of oestrogens on the course of SSD, oestrogen replacement therapy should be considered for postmenopausal patients, who are more vulnerable to side-effects and yet require higher dosages of most antipsychotics to reach similar efficacy. In conclusion, there is a need for tailored, female-specific prescription guidelines, which take into account adjustments required across different phases of life.

Treatment of depression: Are psychotropic drugs appropriately dosed in women and in the elderly? Dosages of psychotropic drugs by sex and age in routine clinical practice

BACKGROUND

Several researchers have shown higher concentration-dose ratios of psychotropic drugs in women and the elderly. Therefore, lower dosages of psychotropic drugs may be recommended in women and the elderly. This study describes sex- and age-related dosage of psychotropic drugs prescribed to patients with major depressive disorder (MDD) in routine clinical practice.

METHOD

Influence of sex and age on dosages are analysed for the 10 most commonly prescribed drugs in our dataset consisting of 32,082 inpatients with MDD. Data stems from the European drug safety program "Arzneimittelsicherheit in der Psychiatrie". The observed sex and age differences in prescriptions are compared to differences described in literature on age- and gender-related pharmacokinetics.

RESULTS

Among patients over 65 years, a statistically significant decrease in dosages with increasing age (between 0.65% and 2.83% for each increasing year of age) was observed, except for zopiclone. However, only slight or no influence of sex-related adjustment of dosage in prescriptions was found.

CONCLUSION

Age appears to influence adjustment of dosage in most psychotropic drugs, but to a lower extent than data on age-related pharmacokinetics suggests. Although literature also suggests that lower dosages of psychotropic drugs may be appropriate for females, this study found women are usually prescribed the same dosage as men.

A Retrospective Analysis of Steady-State Olanzapine Concentrations in Chinese Patients Using Therapeutic Drug Monitoring: Effects of Valproate and Other Factors

BACKGROUND

The objective of this study was to investigate the serum concentrations of olanzapine in relation to age, sex, and other factors in Chinese patients aged between 10 and 90 years.

METHODS

Data for 884 olanzapine patients, deposited between 2016 and 2017, were retrieved from the therapeutic drug monitoring database of the Affiliated Brain Hospital of Guangzhou Medical University. The effects of covariates on serum olanzapine concentration, dose-normalized concentration (C/D ratio), and normalized concentration (C/D/weight) were investigated.

RESULTS

Generally, male patients had lower olanzapine concentration, C/D ratio, and C/D/weight than female patients (P < 0.001). Smoking and drinking reduced olanzapine concentration, C/D ratio, and C/D/weight (P < 0.001). Coadministration with valproate decreased olanzapine concentration, C/D ratio, and C/D/weight by about 16%, 30%, and 40%, respectively (P < 0.001). Patients younger than 60 years had higher olanzapine concentrations (P < 0.05) but lower C/D ratios and C/D/weight (P < 0.001) than patients older than 60 years. Age was correlated with olanzapine concentration (r = -0.082, P < 0.05), C/D ratio (r = 0.196, P < 0.001), and C/D/weight (r = 0.169, P < 0.001). Sample timing after dose and diagnostic factors also contributed to the olanzapine concentrations. Multiple linear regression analysis revealed significant influences of dosage, age, sex, valproate comedication, smoking, postdose interval, and schizophrenia (vs bipolar affective disorders) on serum olanzapine concentrations.

CONCLUSIONS

The metabolism of olanzapine may be altered by several factors. Patients characterized with a combination of factors may benefit from therapeutic drug monitoring for the adjustment of olanzapine dose to minimize adverse reactions.

What to Do About Missed Doses? A Retrospective Study of Olanzapine in the Elderly

Background

Schizophrenia is characterized by a high disease burden. Olanzapine is a common drug used in antipsychotic medication. Little is known about the population pharmacokinetics of olanzapine in elderly patients. Missed doses are a common and unavoidable issue during the treatment of psychiatric diseases, especially in elderly patients. This study aimed to identify what an elderly person should do if doses are inadvertently missed.

Methods

Data were collected from 140 elderly psychiatric patients (aged ≥65 years) who received olanzapine therapy. Olanzapine concentrations were determined by high pressure liquid chromatographic tandem mass spectrometry (HPLC-MS/MS) and a population-based approach was used to quantify the characteristics of elderly patients. A non-linear mixed-effects model was used for data analysis. Simulations based on the final model were applied to predict situations involving a single missed dose or three consecutive missed doses under several remedial regimens.

Results

A total of 474 samples from 140 elderly patients were included in the therapeutic drug monitoring (TDM) data analysis. A one-compartment model, with no significant covariates, was developed to describe the population pharmacokinetics of olanzapine in elderly patients. The population predicted systematic clearance (CL/F) and volumes of distribution (V/F) were 18 L/h and 785 L, respectively. The simulation demonstrated that in a missed dose situation, elderly patients should take the regular dose immediately; the refill dose used at the second remedial time point depends on the length of the time delay.

Conclusion

Here, we used a simulation to provide a remedial regimen for missed doses of olanzapine in the elderly population. Our simulation can provide valuable suggestions for individualized therapy in elderly patients.

Rapid Simultaneous Determination of 14 Antidepressants and 13 Antipsychotics in Human Plasma by Using High-Performance Liquid Chromatography-Tandem Mass Spectrometry With Dynamic Multiple Reaction Monitoring and Its Application to Therapeutic Drug Monitoring

BACKGROUND

A comprehensive, stable, and efficient high-performance liquid chromatography-tandem mass spectrometry method was developed for rapidly analyzing 14 antidepressants and 13 antipsychotics in human plasma for routine clinical therapeutic drug monitoring.

METHODS

Simple protein precipitation was used for the pretreatment of plasma samples; dynamic multiple reaction monitoring was used to avoid the loss of sensitivity caused by numerous ion transitions. In all, 80 ion transitions of 40 compounds were quantitatively determined in 6 minutes.

RESULTS

The limit of detection for the 27 analytes was in the range of 0.1-30 ng/mL, and all calibration lines prepared using blank plasma were linear with a correlation coefficient of r2 ≥ 0.99. The method was accurate and precise with acceptable intraday and interday precisions (coefficients of variation, ≤20% for a lower limit of quantification and ≤15% for other quality control samples) and an accuracy of 85.51%-114.77%. This analysis method has been completely validated and successfully used in routine clinical therapeutic drug monitoring for more than 9963 samples [including 488 samples having drug concentrations above the laboratory alert level (supra-alert-level samples)] at Xiamen Xianyue Hospital.

CONCLUSIONS

This dynamic method is comprehensive (includes most antidepressants and antipsychotics listed in China), reliable (stably used for almost 2 years), and efficient (convenient sample processing and short run time) and provides a large amount of meaningful data for optimized pharmacotherapy. Our experimental data from the plasma concentrations of supra-alert-level samples could serve as a reference for the interpretation of the pharmacokinetics of patients with a high risk of toxicity or loss of tolerability.

Effects of Dose, Age, Sex, Body Weight, and Smoking on Plasma Concentrations of Olanzapine and N-desmethyl Olanzapine in Inpatients With Schizophrenia

PURPOSE

This study aimed to investigate the combined effects of dose, age, sex, body weight, and smoking on plasma concentrations of olanzapine (OLA) and N-desmethyl olanzapine (DMO) in Chinese inpatients with schizophrenia.

METHODS

A retrospective study including 185 inpatients was conducted. The steady-state plasma concentrations of OLA (COLA) and DMO (CDMO) were measured using high-performance liquid chromatography-tandem mass spectrometry. The combined effects of dose, age, sex, body weight, and smoking on COLA and CDMO were evaluated.

FINDINGS

Multiple linear regression analyses revealed that dose, age, body weight, and smoking had significant effects on COLA and CDMO in inpatients with schizophrenia treated with OLA. The dose was the most important determinant of COLA and CDMO and was positively correlated with both. Furthermore, smokers exhibited a significantly lower COLA and COLA + DMO, whereas higher body weight led to the reduction of COLA, CDMO, and COLA + DMO. Advanced age was associated with lower CDMO.

IMPLICATIONS

These results suggest that dose, age, body weight, and smoking have a significant influence on the plasma concentration of OLA and its metabolite DMO. Clinicians should consider the combined effects when prescribing OLA to patients with schizophrenia.

Impact of Body Mass Index on Serum Concentrations of Antidepressants and Antipsychotics

BACKGROUND

Rates of overweight and obesity are higher in patients suffering from psychiatric disorders than in the general population. Body composition and enzyme functions are affected by overweight, and consequently, the pharmacokinetics of drugs may vary in overweight patients. Thus, overweight and obesity are important factors in psychiatric disorders and their treatment. This analysis aimed to investigate the impact of body mass index (BMI) on serum concentrations of the antidepressant drugs amitriptyline, doxepin, escitalopram, mirtazapine, and venlafaxine, and the antipsychotic drugs clozapine, quetiapine, and risperidone, taking into account the following confounding parameters: age, sex, and smoking habit.

METHODS

Inpatients and outpatients (N = 1657) who took at least one of the target drugs were included in this retrospective analysis. Serum concentrations of the target drugs and their metabolites were determined at the Department of Psychiatry, Psychosomatics, and Psychotherapy of the University Hospital of Würzburg during routine therapeutic drug monitoring (January 2009-December 2010), which was performed in the morning (trough level) at steady state.

RESULTS

Dose-corrected serum concentrations (CD) of the active moiety of doxepin and venlafaxine and of O-desmethylvenlafaxine were negatively associated with BMI (partial Pearson correlation, R = -0.267, P = 0.002; R = -0.206, P ≤ 0.001; R = -0.258, P ≤ 0.001), and the CDs were different in normal weight, overweight, and obese patients (analysis of covariance, P = 0.004, P < 0.001, P ≤ 0.001). No association was found between BMI and serum concentrations of amitriptyline, escitalopram, mirtazapine, clozapine, quetiapine, and risperidone.

CONCLUSIONS

In obese patients, higher doses of doxepin and venlafaxine are necessary to achieve similar serum concentrations as in normal weight patients and to avoid treatment-resistant depression.

Impact of age and gender on paliperidone exposure in patients after administration of long-acting injectable formulations-an observational study using blood samples from 1223 patients

PURPOSE

Paliperidone palmitate is an antipsychotic medication available as long-acting injectable (LAI) formulations. The aim of this study was to investigate the effect of age and gender on paliperidone exposure after administration of LAI formulations.

METHODS

Data on serum concentrations of paliperidone from patients using LAI during were included retrospectively from a therapeutic drug monitoring (TDM) service. Information about dose was obtained from the requisition forms. As a measure of exposure, daily dose-adjusted serum concentration (C/D ratio) was used. Based on initial analysis of C/D ratios versus age, a breaking point close to 50 years was observed, thus deciding the grouping of patients as older (≥50 years) or younger (15-49 years). Linear mixed model analyses, allowing multiple measurements per patients, were used.

RESULTS

In total, 1223 patients were included, whereof 1158 patients used paliperidone LAI in once-monthly intervals. In these patients (27.9% older), older patients had significantly higher paliperidone C/D ratio than younger patients (+20%, p<0.001). Compared to males, females had higher C/D ratio (+14%; p<0.001). Subsequently, older female users of once-monthly LAI intervals had 41% higher paliperidone C/D ratios compared to younger males (15.0 vs. 21.2 nM/mg; p<0.001). Compared to females aged 21-30 years, females with high age (≥70 years) had at least 105% higher paliperidone C/D ratio (p<0.001).

CONCLUSION

The present study shows that older age and female gender are associated with higher paliperidone exposure than younger age and males, respectively. Particularly, older female patients (>50 years) are likely exposed to high concentration and cautious dosing in this subgroup is required.

Dose-Corrected Serum Concentrations and Metabolite to Parent Compound Ratios of Venlafaxine and Risperidone from Childhood to Old Age

OBJECTIVE

Comparative pharmacokinetic data about the antidepressant venlafaxine (VEN) and the antipsychotic drug risperidone (RIS) over the lifespan and especially in children and adolescents is lacking. This is the first cross-sectional study that aimed to investigate differences in dose-corrected serum concentrations (CDs) and metabolite to parent compound ratios (MPRs) of VEN and RIS across the lifespan.

METHODS

Patients treated with VEN and RIS at the University Hospital of Würzburg, Germany were included in the study. Serum level determinations were performed during clinical routine care. Patients with CYP2D6 influencing co-medication were excluded from analyses.

RESULTS

In 953 patients (12-93 years) treated with VEN and 552 patients (7-92 years) treated with RIS, children/adolescents (<18 years) showed 11% and 19%, and 44% and 42% lower CDs of the active moieties (CDs_AM) of VEN and RIS than adults and elderly (≥60 years) (Kruskal-Wallis tests; p ≤ 0.001). However, when CDs were normalized to body weight, a different pattern emerged. Gender differences, with higher CDs_AM in females were present in adults and elderlies but not in children/adolescents. No gender- or age-dependent difference in MPRs was found; however, 80% of MPRs of RIS in children/adolescents were below the range of "normal" CYP2D6 function for adults.

CONCLUSIONS

We suggest a higher clearance as a reason for lower CDs_AM of VEN and RIS in children/adolescents compared to adults/elderlies. Metabolism of VEN or RIS by CYP2D6, characterized by MPRs, was not associated with age. However, MPRs of RIS were lower in children/adolescents, possibly due to a higher renal clearance of 9-OH-risperidone.

Effects of Age, Drug Dose, and Sampling Time on Salivary Levels of Olanzapine, Quetiapine, and Their Metabolites

Although blood is the basic test material to monitor levels of antipsychotic drugs in a person’s system, saliva could serve as a more convenient test material. Therefore, the aim of this novel study was to determine the correlations between the salivary levels of olanzapine and quetiapine (and their metabolites: N-demethyl olanzapine and norquetiapine) and the patient’s sex and age, dose level, and the time of sampling. The study involved two groups of patients: 21 female patients starting treatment immediately after being admitted to the hospital and 36 male and female nursing home residents, long-time users of the studied drugs. Women had lower levels of the tested analytes than men. Quetiapine levels in the saliva of people starting the treatment showed a positive correlation with the age of the patients and a strong positive correlation with the dose level. The saliva levels of olanzapine showed a strong correlation with its metabolite in patients who had recently started treatment. Among long-time users of this drug, salivary levels differed significantly before and after administration. In conclusion, the results indicate that there is a possibility of using saliva as a material for monitoring quetiapine or olanzapine concentrations, especially in people starting treatment.

Impact of age and CYP2D6 genotype on exposure of zuclopenthixol in patients using long-acting injectable versus oral formulation-an observational study including 2044 patients

PURPOSE

Zuclopenthixol is an antipsychotic available as oral and long-acting injectable (LAI) formulations. The aim of this study was to investigate the effect of age on zuclopenthixol exposure during oral and LAI administrations without and with adjustment for CYP2D6 genotype.

METHODS

Data on serum concentrations of zuclopenthixol and CYP2D6 genotype (available for 28.2% of the population) from patients using oral or LAI zuclopenthixol were included retrospectively from a therapeutic drug monitoring service during the period 2005-2019. As a measure of exposure, dose-adjusted serum concentration (C/D ratio) was used. Based on age, patients were grouped to older (≥ 65 years) or younger (18-64 years). Linear mixed model analyses without and with adjustment for CYP2D6 genotype were used.

RESULTS

Serum concentrations of zuclopenthixol from 1145 (14.1% older) and 899 patients (24.6% older) in the LAI and oral groups were included, respectively. Compared with younger patients, older patients had a higher C/D ratio of zuclopenthixol for LAI (+ 25-33%, p < 0.001) and oral formulation (+ 25-29%, p ≤ 0.003) without and with adjustment for CYP2D6 genotype. The doses were lower in older versus younger patients (oral: - 30%; LAI: - 20%; p < 0.001). Compared with the younger LAI users without reduced CYP2D6 function, a higher C/D ratio was observed in the older LAI users with reduced CYP2D6 function (+ 104%, p < 0.001).

CONCLUSION

The present study showed that zuclopenthixol exposure increases in older patients and that the older LAI users with reduced CYP2D6 function are exposed to high serum concentrations. Also, the present study showed that similar dose reductions are required for oral and LAI users.

Antipsychotic-induced Hyperprolactinemia in aging populations: Prevalence, implications, prevention and management

This paper reviews the prevalence, implications, prevention and management of antipsychotic-induced hyperprolactinemia in aging populations. Antipsychotics are indicated mainly for the treatment of psychotic illness but are also used in other conditions. Complications induced by antipsychotics increase with age, due to age-related changes in drug metabolism and excretion. Almost all antipsychotics lead to hyperprolactinemia by blocking dopamine D2 receptors in the anterior pituitary gland, which counteracts dopamine's inhibitory action on prolactin secretion. The main findings of this narrative review are that, though many of the known side effects of high prolactin levels lose their salience with age, the risk of exacerbating osteoporosis remains critical. Methods of preventing antipsychotic-induced hyperprolactinemia in older individuals include using antipsychotic medication (AP) as sparingly as possible and monitoring AP serum levels, regularly measuring prolactin levels, closely monitoring bone density, treating substance abuse, and teaching patients stress management techniques. When hyperprolactinemia symptoms cannot be otherwise managed, adjunctive drugs are available. Potential helpful adjuncts are: dopamine agonists, antipsychotics with partial agonist properties (e.g. aripiprazole), selective estrogen receptor modulators, and metformin. Because a gold standard for prevention/treatment has not been established, clinical decisions need to be made based on safety and individual circumstance.

Pharmacokinetics and Bioequivalence of 2 Olanzapine Orally Disintegrating Tablet Products in Healthy Chinese Subjects Under Fed and Fasting Conditions

To assess the bioequivalence of two 5-mg olanzapine orally disintegrating tablet (ODT) products, 2 randomized, open-label, single-dose, 2-way crossover studies were carried out under fasting or fed conditions. Blood samples were collected at scheduled times according to the study protocol. Statistical analysis of area under the concentration-time curve from time 0 to 168 hours (AUC_0-t ), area under the curve from time zero to infinity (AUC_0-∞ ), and peak plasma concentration (C_max ) was conducted. Two formulations were considered bioequivalent if the 90% confidence intervals (CIs) of the geometric mean ratios for AUC_0-t, AUC_0-∞ , and C_max were within the range of 0.80-1.25. Adverse events were recorded and evaluated throughout the studies. A total of 48 subjects with 24 in each study completed the 2 studies. In fasted subjects, the 90%CIs for the test product versus the reference product were 97.28%-105.13% for AUC_0-t , 97.57%-105.54% for AUC_0-∞ , and 90.94%-103.97% for C_max . In fed subjects, the 90%CIs for AUC_0-t , AUC_0-∞ and C_max were 99.73%-122.63%, 99.56%-121.75%, and 99.46%-120.46%, respectively. No serious adverse events were reported in the studies. The reference and the test product of 5-mg olanzapine ODT show comparable pharmacokinetic profiles under both fed and fasted conditions and were considered bioequivalent.

We are more than our omics

Today, personalized medicine is essentially based on individual "omics." However there is a need to integrate this approach with a number of data such as pharmacokinetics, optimal dose and duration of drug treatments, age and gender differences, and drug interactions, which are relevant in terms of benefits and risks but are frequently unknown. This requires independent research that should be supported by governments in order to make personalized medicine a reality.

The Effect of Valproic Acid on Olanzapine Serum Concentration: A Study Including 2791 Patients Treated With Olanzapine Tablets or Long-Acting Injections

BACKGROUND

The combination of olanzapine and valproic acid (VPA) is regularly prescribed in the treatment of bipolar or schizoaffective disorders. The VPA has been shown to reduce olanzapine concentration, but the mechanism behind this interaction remains unknown. We aimed to investigate the effect of VPA on olanzapine concentration during oral versus long-acting injectable (LAI) formulation in a real-life setting.

METHODS

From a therapeutic drug monitoring service, prescribed doses and serum concentrations from 2791 olanzapine-treated patients (9433 measurements) were included.

RESULTS

The number of patients on olanzapine-LAI treatment was 328, whereas 2463 were using oral olanzapine. The frequency of patients comedicated with VPA was 9.4% for olanzapine tablets and 5.8% for olanzapine-LAI. The VPA had no effect on olanzapine dose-adjusted concentrations in LAI users (1.6 vs 1.7 [ng/mL]/[mg/d]; P = 0.38), whereas in the oral group the dose-adjusted olanzapine concentration was lower in VPA users (2.2 vs 2.7 [ng/mL]/[mg/d]; P < 0.001). For smokers in the oral olanzapine group using VPA, 8.7% of the measurements were in the subtherapeutic range (<10 ng/mL) compared with 6.0% in nonusers (P = 0.003).

IMPLICATIONS

These findings show that the VPA-olanzapine interaction involves a presystemic mechanism and is therefore restricted to oral olanzapine treatment. For oral treatment of olanzapine, comedication with VPA implies a risk of insufficient effect, which may be of clinical relevance in smokers in particular. Thus, it is important to be aware of the interaction potential with VPA during oral olanzapine use, whereas for LAI-treated patients fewer precautions are required from a pharmacokinetic point of view.

Understanding variability in the pharmacokinetics of atypical antipsychotics - focus on clozapine, olanzapine and aripiprazole population models

Antipsychotic medicines are widely used for the management of psychotic symptoms regardless of the underlying diagnosis. Most atypical antipsychotics undergo extensive metabolism prior to excretion. Various factors may influence their pharmacokinetics, particularly elimination, leading to highly variable drug concentrations between individual patients following the same dosing regimen. Population pharmacokinetic approach, based on nonlinear mixed effects modeling, is a useful tool to identify covariates explaining pharmacokinetic variability, as well as to characterize and distinguish unexplained residual and between-subject (interindividual) variability. In addition, this approach allows the use of both sparsely and intensively sampled data. In this paper, we reviewed the pharmacokinetic characteristics of clozapine, olanzapine and aripiprazole, focusing on a population modeling approach. In particular, models based on a nonlinear mixed effects approach performed by NONMEM^® software in order to identify and quantify sources of pharmacokinetic variability are presented. Population models were identified through systematic searches of PubMed and sixteen studies were selected. Some of the factors identified that significantly contribute to variability in elimination among clozapine, olanzapine, and aripiprazole are demographic characteristics, body weight, genetic polymorphism, smoking and in some cases drug interactions. Scientific research based on pharmacometric modeling is useful to further characterize sources of variability and their combined effect.