Determination of plasma concentration reference ranges for oral aripiprazole, olanzapine, and quetiapine

How to Determine a Therapeutic Reference Range for a Psychotropic Drug Systematically? Recommendations of the TDM Task Force of the AGNP

BACKGROUND

Therapeutic drug monitoring (TDM) is essential for controlling pharmacogenetic and pharmacokinetic variations and for optimizing pharmacotherapy. However, its value is often underestimated because of nonsystematic recommendations for target ranges in the literature. The purpose of this study was to emphasize transparency and systematization in the forthcoming Updates to the Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie (AGNP)-TDM Consensus Guidelines.

METHODS

Here, a stepwise method for determining therapeutic reference ranges (TRRs) in psychiatry is introduced. By using various data types, a multidimensional approach for establishing a range is presented. The data types were classified based on how effectively they supported the target ranges. This method was demonstrated for 3 drugs commonly used in psychiatry (aripiprazole, olanzapine, and escitalopram).

RESULTS

Despite the methodological shortcomings in published concentration-effect studies, the approach used here enabled the determination of reference ranges by combining multiple types of data. The lower limit of the TRR is ideally derived from studies that link blood drug concentrations to clinical effectiveness, particularly symptom-specific responses, after fixed-dose treatment. The upper limit depends on the concentrations associated with adverse reactions or maximal response. Thresholds can be estimated using receiver operating characteristic analyses. Preliminary thresholds were derived from responder concentration data or from expected drug concentrations under approved doses. Positron emission tomography studies were used to further validate these ranges.

CONCLUSIONS

This study proposed a new standard for determining the TRR of psychotropic drugs, thereby enhancing their clinical utility and validity. Adjusting blood levels to these ranges should improve response rates and medication tolerance.

From Psychiatry to Oncology: Exploring the Anti-Neoplastic Mechanisms of Aripiprazole and Its Potential Use in Cancer Treatment

Drug repurposing provides a cost-effective and time-saving approach to cancer therapy. Aripiprazole (ARI), a third-generation antipsychotic, has shown potential anticancer properties by modulating pathways central to tumor progression and resistance. This scoping review systematically examines evidence on ARI's anticancer effects, mechanisms of action, and translational potential. A systematic search of PubMed, EMBASE, SCOPUS, and Web of Science was conducted following PRISMA-ScR guidelines. Eligible studies included in vitro, in vivo, and clinical investigations. Data on cancer types, pathways, assays, and outcomes were extracted and synthesized to identify trends and gaps. Of 588 screened studies, 23 met inclusion criteria, spanning cancer types such as breast, colorectal, lung, and brain cancers. ARI modulates key pathways like PI3K/AKT/mTOR and Wnt/β-catenin, induces apoptosis through mitochondrial dysfunction and ER stress, and overcomes drug resistance by inhibiting P-glycoprotein activity and expression. It exhibits tumor-suppressive effects in vivo and synergizes with chemotherapy and radiotherapy. Retrospective population studies suggest ARI's prolactin-sparing properties may reduce the risk of hormone-sensitive cancers such as breast and endometrial cancer compared to antipsychotics with stronger dopamine receptor blockade. Additionally, ARI's ability to target multiple Hallmarks of Cancer highlights its promise as a repurposed anticancer agent. However, current evidence is primarily preclinical and observational, with limited clinical validation. Large-scale cohort studies and prospective trials are essential to confirm its efficacy and address translational challenges. By bridging these gaps, ARI could emerge as a valuable adjunctive therapy in oncology, leveraging its safety profile and versatility to address unmet needs in cancer treatment.

Glucosylceramide Synthase Inhibition in Combination with Aripiprazole Sensitizes Hepatocellular Cancer Cells to Sorafenib and Doxorubicin

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer deaths due to its late diagnosis and restricted therapeutic options. Therefore, the search for appropriate alternatives to commonly applied therapies remains an area of high clinical need. Here we investigated the therapeutic potential of the glucosylceramide synthase (GCS) inhibitor Genz-123346 and the cationic amphiphilic drug aripiprazole on the inhibition of Huh7 and Hepa 1-6 hepatocellular cancer cell and tumor microsphere growth. Single and combinatorial treatments with both drugs at 5 µM concentration led to efficient cell cycle arrest, reduced expression of cyclins A and E, increased lipid storage in lysosomal compartments, accompanied by increased uptake of lysotracker, and elevated expression of the autophagy marker Lc3 II. Both drugs affected mitochondrial function, indicated by altered mitotracker uptake and impaired mitochondrial respiration. Aripiprazole in monotherapy, or even more pronounced in combination with Genz, also potentiated the effect of the cytostatic drugs sorafenib and doxorubicin on tumor cell- and tumor spheroid-growth inhibition. Targeting GCS with Genz with the parallel application of cationic amphiphilic drugs such as aripiprazole in combination with cytostatic drugs may thus represent a potent therapeutic approach in the treatment of HCC and potentially other cancer types.

Association between olanzapine plasma concentrations and treatment response: A systematic review, meta-analysis and individual participant data meta-analysis

AIMS

By meta-analysing pooled studies and available individual participant data, we aim to provide new insight on olanzapine therapeutic drug monitoring in schizophrenia.

METHOD

We conducted a computerized search of bibliographic databases (Pubmed, Cochrane library, Web of Science and PsycINFO) to identify studies that assessed the relationship between olanzapine plasma concentration and the change in patients' clinical scores. We investigated this relationship with olanzapine plasma level 12h00 post-intake using a random-effects model.

RESULTS

7 studies were included in the pooled data analysis (781 patients). We found no difference in oral dose between responders and non-responders but a significantly higher concentration of 4.50 µg/L in responders (p < 0.01). Olanzapine concentration above the thresholds identified in each study was associated with response (odd ratio = 3.50, p = 0.0007). We identified that non-responder patients showed greater inter-individual variability than responders. In the individual data analysis (159 patients), we found no relationship between dose and clinical response but an association between plasma level and response in the shape of a parabolic curve. The Receiver Operating Characteristic curve found a threshold of 22.07 µg/L to identify responders (96% sensitivity, 86% specificity) and a threshold of 56.47 µg/L to identify a decreased probability of response.

CONCLUSION

In contrast to oral dose, our work confirmed that plasma olanzapine levels are associated with clinical response and should therefore be used to optimise treatment. We determined a treatment response threshold of 22.07 µg/L and suggest that a concentration above the therapeutic window may result in a decreased response.

Insights into the population pharmacokinetics and pharmacodynamics of quetiapine: a systematic review

INTRODUCTION

Quetiapine exhibits notable pharmacokinetic and pharmacodynamic (PK/PD) variability, the origins of which are poorly understood. This systematic review summarizes published population PK/PD studies and identifies significant covariates accounting for this variability to inform precision dosing.

METHODS

We systematically searched the PubMed, Web of Science, and Embase databases and compared study characteristics, model parameters, and covariate effects. Visual predictive distributions were used to compare different models. Forest plots and Monte Carlo simulations were used to assess the influence of covariates.

RESULTS

Six population PK and three population PK/PD studies were included. The median apparent clearance in adults was 87.7 L/h. Strong and moderate cytochrome P450 3A4 inducers increased the apparent clearance approximately fourfold, while strong cytochrome P450 3A4 inhibitors reduced it by 93%. The half-maximum effect concentrations were 82.8 ng/mL for the Brief Psychiatric Rating Scale and 583 ng/mL for dopamine D2 receptor occupancy. Both treatment duration and quetiapine exposure were associated with weight gain.

CONCLUSIONS

Concurrent administration of potent or moderate CYP3A4 inducers and inhibitors need to be avoided in quetiapine-treated patients. When co-medication is required, it is recommended to adjust the dosage based on therapeutic drug monitoring. Additional research is warranted to delineate the dose-exposure-response relationships of quetiapine and active metabolite norquetiapine in pediatrics, geriatrics, hepatically-impaired patients, and women using contraceptives or are pregnant or menopausal.

PROSPERO REGISTRATION

CRD42023446654.

Differences in autonomic nervous system activity between long-acting injectable aripiprazole and oral aripiprazole in schizophrenia

BACKGROUND

Distinct oral atypical antipsychotics have different effects on autonomic nervous system (ANS) activity. Among them, oral aripiprazole has been linked to dysfunction of the ANS in schizophrenia. Long-acting injectable aripiprazole is a major treatment option for schizophrenia, but the effect of the aripiprazole formulation on ANS activity remains unclear. In this study, we compared ANS activity between oral aripiprazole and aripiprazole once-monthly (AOM) in schizophrenia.

METHODS

Of the 122 patients with schizophrenia who participated in this study, 72 received oral aripiprazole and 50 received AOM as monotherapy. We used power spectral analysis of heart rate variability to assess ANS activity.

RESULTS

Patients who received oral aripiprazole showed significantly diminished sympathetic nervous activity compared with those who received AOM. Multiple regression analysis revealed that the aripiprazole formulation significantly influenced sympathetic nervous activity.

CONCLUSION

Compared with oral aripiprazole, AOM appears to have fewer adverse effects, such as sympathetic nervous dysfunction.

Therapeutic Reference Range for Aripiprazole in Schizophrenia Revised: a Systematic Review and Metaanalysis

RATIONALE

While one of the basic axioms of pharmacology postulates that there is a relationship between the concentration and effects of a drug, the value of measuring blood levels is questioned by many clinicians. This is due to the often-missing validation of therapeutic reference ranges.

OBJECTIVES

Here, we present a prototypical meta-analysis of the relationships between blood levels of aripiprazole, its target engagement in the human brain, and clinical effects and side effects in patients with schizophrenia and related disorders.

METHODS

The relevant literature was systematically searched and reviewed for aripiprazole oral and injectable formulations. Population-based concentration ranges were computed (N = 3,373) and pharmacokinetic influences investigated.

RESULTS

Fifty-three study cohorts met the eligibility criteria. Twenty-nine studies report blood level after oral, 15 after injectable formulations, and nine were positron emission tomography studies. Conflicting evidence for a relationship between concentration, efficacy, and side effects exists (assigned level of evidence low, C; and absent, D). Population-based reference ranges are well in-line with findings from neuroimaging data and individual efficacy studies. We suggest a therapeutic reference range of 120-270 ng/ml and 180-380 ng/ml, respectively, for aripiprazole and its active moiety for the treatment of schizophrenia and related disorders.

CONCLUSIONS

High interindividual variability and the influence of CYP2D6 genotypes gives a special indication for Therapeutic Drug Monitoring of oral and long-acting aripiprazole. A starting dose of 10 mg will in most patients result in effective concentrations in blood and brain. 5 mg will be sufficient for known poor metabolizers.

Dose-Related Reference Range as a Tool in Therapeutic Drug Monitoring

BACKGROUND

Therapeutic drug monitoring (TDM) aims to individualize drug therapy. This systematic review provides a state-of-the-art overview of the benefits of adding the dose-related reference range (DRR) as a second reference range to the set of tools used by TDM for measurement and evaluation. It discusses alternative pharmacokinetic approaches for individualization of drug therapy.

METHODS

Literature was searched in PubMed. Textbooks provided Bateman transformations for calculating expected drug concentrations at various times after drug application in "normal patients," that is, the population of phase II clinical trials. The review compiles conditions and prerequisites for these transformations to be valid.

RESULTS

Relating a measured drug concentration to the orienting therapeutic reference range provides pharmacodynamic information for improving the benefit-to-risk ratio of desired drug effects versus adverse drug effects. The discriminating DRR considers a patient's individual pharmacokinetic situation. DRR is statistically based on the pharmacokinetic parameters total clearance, time to reach maximal concentrations, and elimination half-life. Relating the measured drug concentration to a range rather than a particular value, DRR determines if individual patients do or do not belong to the population of "normal patients." Once a patient is identified to be outside the population of "normal patients," the clinical-pharmacological TDM report elaborates the cause. It consists of the measured value, the TDM 9-field-board, the elimination pathways table, and a medication recommendation taking into account clinical information. The internet-based platform KONBEST supports editing of the clinical-pharmacological TDM report. It is personally signed and send to the therapist.

CONCLUSIONS

The DRR embedded into a clinical-pharmacological TDM report allows adjusting a patient's medication to the patient's individual needs (individualization of drug therapy).

Blockade of multiple monoamines receptors reduce insulin secretion from pancreatic β-cells

Clinical use of olanzapine frequently causes severe hyperglycemia as an adverse effect. In this study, we elucidated mechanisms by which olanzapine reduced insulin secretion using the hamster pancreatic β-cell line HIT-T15. Reverse transcriptional-PCR analysis revealed expression of dopamine (D₂, D₃ and D₄), serotonin (5-HT_2A, 5-HT_2B, 5-HT_2C, and 5-HT₆), and histamine (H₁ and H₂) receptors in HIT-T15 cells. Olanzapine decreased insulin secretion from HIT-T15 cells at clinically relevant concentrations (64–160 nM). A dopamine D₂ agonist, D₃ antagonist, and D₄ antagonist suppressed insulin secretion, whereas a D₂ antagonist and D₃ agonist increased it. A serotonin 5-HT_2B agonist slightly increased insulin secretion, while a 5-HT_2C antagonist slightly decreased it. Other agonists and antagonists for serotonin receptors did not affect insulin secretion. A histamine H₁ agonist increased insulin secretion, whereas an H₁ antagonist and H₂ agonist suppressed it. Our results suggest that dopamine (D₂, D₃ and D₄), serotonin (5-HT_2B and 5-HT_2C), and histamine (H₁ and H₂) receptors, which are expressed on pancreatic β-cells, directly modulate insulin secretion from pancreatic β-cells. Thus, olanzapine may induce hyperglycemia in clinical settings by suppressing insulin secretion from pancreatic β-cells through inhibition of dopamine D₃, serotonin 5-HT_2B and 5-HT_2C, and histamine H₁ receptors.

Relationship between antipsychotic blood levels and treatment failure during the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) study

OBJECTIVE

Antipsychotic blood levels (ABLs) may help identify patients at risk for treatment failure. Reference ranges (RR) for plasma concentrations of ABLs that account for between-patient variability were developed for risperidone and olanzapine based on population pharmacokinetic models. The Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) collected clinical outcomes and ABLs, allowing testing of the relationship of ABLs with outcomes.

METHODS

ABLs from 694 patients who were randomized to olanzapine or risperidone were compared to the 80% RRs and were assessed as below or within/above the RR. Treatment failure was defined per any of these criteria: (1) emergency room visit for psychiatric reasons, (2) hospitalization for psychiatric reasons, (3) adverse event of completed suicide, suicidal ideation, or suicide attempt, (4) assaultive behavior, (5) arrested or jailed, (6) 2-point increase from baseline in Clinical Global Impression-Severity score, (7) 25% increase in Positive and Negative Syndrome Scale total score. Patients assessed with treatment failure within 100 days of drug concentration measurement were analyzed.

RESULTS

Treatment failure occurred in 126 of 323 patients. The proportion of patients with ABLs below RR was 18.3% (59/323) compared to 10% expected in a fully adherent population. Among the 59 with ABLs below RR, 50.8% had treatment failure (compared to 36.4% for the 264 with ABLs within/above RR). The difference between groups was significant (odds ratio = 1.810; 95% CI = 1.025, 3.197; p = 0.0408).

CONCLUSIONS

Analysis of CATIE data showed that ABLs within the context of RRs may identify patients with higher risk of relapse.