Changes in psychopathology in schizophrenia patients starting treatment with new-generation antipsychotics: therapeutic drug monitoring in a naturalistic treatment setting

A Pilot Study of Plasma Antipsychotic Drugs Concentrations of First Episode Patients with Psychosis From Epirus - Greece

Background:

This contribution is a study on plasma antipsychotics concentrations of first episode outpatients with psychosis (FEPs), under antipsychotic treatment; it aims to attract attention to the importance of the drug-driven management of psychiatric patients for improving adherence and clinical efficacy.

Methods:

The plasma antipsychotic concentrations were determined retrospectively (after the completion of selection of all samples) and therefore, they were not used to monitor patients’ response to pharmacotherapy. A total of 120 plasma samples from 35 psychiatric patients were collected and tested for antipsychotics. The concentrations of eight antipsychotic drugs (amisulpride, aripiprazole, clozapine, haloperidol, olanzapine, quetiapine, risperidone and paliperidone) and seven of their metabolites were determined.

Results:

Overall, 74% of the samples had therapeutic antipsychotic levels, 19% had subtherapeutic concentrations, while supra-therapeutic concentrations were measured for clozapine (7%). Therapeutic drug concentrations were recorded in 54% of plasma samples from patients being under olanzapine medication and in all patients under long-acting injectables. Sub-therapeutic levels were either attributed to non-adherence, or they reflected residual levels due to medication changes. Supra-therapeutic levels were recorded for clozapine and were not followed by adverse effects.

Conclusion:

This is the first study on antipsychotic plasma levels conducted in Greece. Our results show the importance of performing measurement of plasma antipsychotics levels, at appropriate time intervals, for improving adherence, clinical decision making and thus clinical efficacy. Especially for FEPs, such approach could contribute to early detection of treatment limitations and improve outcome.

Concentration-Effect Relationships of Psychoactive Drugs and the Problem to Calculate Therapeutic Reference Ranges

BACKGROUND

Despite the obvious potential of Therapeutic Drug Monitoring (TDM) as a tool to optimize psychopharmacotherapy, especially treatment with mood-stabilizing, antidepressant and antipsychotic drugs, acceptance of TDM as a routine tool is still limited. A serious scientific argument against the regular use of TDM is the lack of evidence for a concentration-dependent clinical effect. The aim of this review was to highlight methodological problems leading to poor or even negative concentration-effect relationships and to show how therapeutically effective concentrations of psychoactive drugs can be determined using routine TDM databases.

METHODS

Reports on concentration-effect relationships of psychoactive drugs were analyzed with regard to applied methods. From routine TDM databases of patients who had been treated with antidepressant or antipsychotic drugs and whose improvement was measured by the clinical global impressions scale, mean and median drug concentrations were calculated and compared with reference ranges recommended by TDM guidelines.

RESULTS

Few fixed-dose studies with adequate design and data analysis demonstrated a correlation between drug concentration and clinical effect for psychoactive drugs. Most studies, however, mostly retrospective analyses of TDM databases, failed to find significant concentration-effect relationships because of flexible dosing. They were not suitable for the determination of therapeutically effective drug concentrations. Using TDM databases of antidepressant and antipsychotic drug concentrations in blood of patients who were categorized as responders by the clinical global impressions score, the interquartile ranges of drug concentrations (25th-75th percent range) can be shown to be very close to the therapeutic reference ranges recommended in guidelines for TDM in psychiatry.

CONCLUSIONS

This review provides a discussion on why simple correlation analyses of psychoactive drug concentrations in blood and clinical effects are obsolete for flexible-dose studies or TDM databases. TDM databases, however, can and should be used to calculate drug concentrations in blood of patients who had responded to the drugs. Interquartile ranges can be regarded and used as preliminary therapeutic reference ranges.

Why do indiviuals with schizophrenia drop out of observational clinical trials?

Randomized controlled trials (RCTs) and observational studies frequently differ with regard to study dropouts. The present naturalistic follow-up investigation aimed to shed a light on this issue by evaluating the time to and the reasons for study dropout in patients suffering from schizophrenia who started monotherapy with an oral new-generation antipsychotic. To this end, psychopathological symptoms and safety data were assessed in 194 patients who were followed up to a maximum observation period of twelve months. 9.3% of study participants completed the study. The mean time to study dropout was 2.6 ± 2.7 months with almost two thirds of patients dropping out within three months. 44.3% discontinued medication at the date of study dropout, the remainders dropped out due to withdrawal of written consent, logistic reasons, or nonappearance to the study visit ("loss to follow-up"), which were not necessarily to be equated with cessation of the antipsychotic. These findings indicate that in contrast to RCTs, dropout of observational studies is not necessarily associated with drug discontinuation. Accordingly, systematic differences between trial designs need to be considered when interpreting the results of clinical trials.

Generating human serotonergic neurons in vitro: Methodological advances

Technologies for deriving human neurons in vitro have transformed our ability to study cellular and molecular components of human neurotransmission. Three groups, including our own, have recently published methods for efficiently generating human serotonergic neurons in vitro. Remarkably, serotonergic neurons derived from each method robustly produce serotonin, express raphe genes, are electrically active, and respond to selective serotonin reuptake inhibitors in vitro. Two of the methods utilize transdifferentiation technology by overexpressing key serotonergic transcription factors. The third and most recent method involves differentiating induced pluripotent stem cells (iPSCs) to serotonergic neurons using developmental patterning cues. In this mini-review, we briefly describe the developmental programs governing serotonergic specification in vivo and how they have been harnessed to achieve serotonergic differentiation in vitro. We discuss the distinct and overlapping features of the recently published methodologies and their value in the context of in vitro disease modeling. Also see the video abstract here.