A systematic review of aripiprazole--dose, plasma concentration, receptor occupancy, and response: implications for therapeutic drug monitoring

Impact of Preoperative Aripiprazole on Postoperative Analgesia in Laparoscopic Hysterectomy: A Randomized Double-blind Placebo-controlled Trial

OBJECTIVES

Aripiprazole is a second-generation atypical antipsychotic with worldwide clinical approval. Nevertheless, its perioperative antinociceptive application has not been studied. As a result, the purpose of this study was to investigate the analgesic effects of perioperative aripiprazole on reducing postoperative pain, as well as the possible adverse effects.

PATIENTS AND METHODS

This randomized controlled study enrolled 80 female patients scheduled for laparoscopic hysterectomy who were assigned randomly into 2 equal groups in 1:1; aripiprazole group (n = 40), patients received an aripiprazole 30 mg tablet orally 3 hours before surgery and placebo group (n = 40), patients received a placebo tablet 3 hours before surgery. The 24-hour morphine consumption postoperatively was the primary outcome, and the time to the first analgesic request, sedation scores, and the incidence of perioperative adverse events were the secondary outcomes.

RESULTS

The mean 24-hour morphine consumption was significantly lower with aripiprazole (2.5 ± 0.5 mg) than with placebo (23.7 ± 1.6 mg; mean ± SE -21.2 ± 0.3, 95% CI: -21.7 to -20.6, P < 0.001). In addition, the mean time to the first analgesic request was significantly longer with aripiprazole (212.2 ± 14.7 min) than with placebo (27.0 ± 2.0 min; mean ± SE 185.2 ± 2.3, 95% CI: 180.5 to 189.8, P < 0.001). Furthermore, the aripiprazole group reported higher sedation scores ( P < 0.001). Bradycardia and hypotension were reported more frequently among patients in the aripiprazole group ( P < 0.05).

CONCLUSION

Aripiprazole was effective in reducing pain after laparoscopic hysterectomy. Although self-limited, side effects should be taken into consideration when using the medication perioperatively.

Update Lessons from Positron Emission Tomography Imaging Part I: A Systematic Critical Review on Therapeutic Plasma Concentrations of Antipsychotics

BACKGROUND

Positron emission tomography (PET) and single photon emission tomography (SPECT) of molecular drug targets (neuroreceptors and transporters) provide essential information for therapeutic drug monitoring-guided antipsychotic drug therapy. The optimal therapeutic windows for D 2 antagonists and partial agonists, as well as their proposed target ranges, are discussed based on an up-to-date literature search.

METHODS

This part I of II presents an overview of molecular neuroimaging studies in humans and primates involving the target engagement of amisulpride, haloperidol, clozapine, aripiprazole, olanzapine, quetiapine, risperidone, cariprazine, and ziprasidone. The systemic review particularly focused on dopamine D 2 -like and 5-HT 2A receptors. Target concentration ranges were estimated based on receptor occupancy ranges that relate to clinical effects or side effects (ie, extrapyramidal side effects). In addition, findings for other relevant receptor systems were included to further enrich the discussion.

RESULTS

The reported reference ranges for aripiprazole and clozapine align closely with findings from PET studies. Conversely, for haloperidol, risperidone, and olanzapine, the PET studies indicate that a lowering of the previously published upper limits would be necessary to decrease the risk of extrapyramidal side effect.

CONCLUSIONS

Molecular neuroimaging studies serve as a strong tool for defining target ranges for antipsychotic drug treatment and directing therapeutic drug monitoring.

How to classify antipsychotics: time to ditch dichotomies?

The dichotomies of 'typical/atypical' or 'first/second generation' have been employed for several decades to classify antipsychotics, but justification for their use is not clear. In the current analysis we argue that this classification is flawed from both clinical and pharmacological perspectives. We then consider what approach should ideally be employed in both clinical and research settings.

Evidence for Therapeutic Drug Monitoring of Atypical Antipsychotics

Second-generation antipsychotics (SGAs), also known as atypical antipsychotics, are a newer class of antipsychotic drugs used to treat schizophrenia, bipolar disorder, and related psychiatric conditions. The plasma concentration of antipsychotic drugs is a valid measure of the drug at its primary target structure in the brain, and therefore determines the efficacy and safety of these drugs. However, despite the well-known high variability in pharmacokinetics of these substances, psychiatric medication is usually administered in uniform dosage schedules. Therapeutic drug monitoring (TDM), as the specific method that can help personalised medicine in dose adjustment according to the characteristics of the individual patient, minimizing the risk of toxicity, monitoring adherence, and increasing cost-effectiveness in the treatment, thus seems to be an elegant tool to solve this problem. Non-response to therapeutic doses, uncertain adherence to medication, suboptimal tolerability, or pharmacokinetic drug-drug interactions are typical indications for TDM of SGAs. This review aims to summarize an overview of the current knowledge and evidence of the possibilities to tailor the dosage of selected SGAs using TDM, including the necessary pharmacokinetic parameters for personalised pharmacotherapy.

Implementing gradual, hyperbolic tapering of long-acting injectable antipsychotics by prolonging the inter-dose interval: an in silico modelling study

Gradual, hyperbolic tapering has been proposed as a method to reduce the risk of withdrawal effects and potential relapse of an underlying condition by minimising disruption of existing equilibria. We applied hyperbolic tapering principles in silico to long-acting aripiprazole to generate regimens for withdrawal in clinical practice. We derived thresholds for taper rates using existing studies and consensus. Using pharmacokinetic data for aripiprazole long-acting injectable antipsychotic (ALAI), we conducted in silico modelling to examine the impact of abrupt cessation of long-acting injectable antipsychotic (LAI) medication and the effect of prolonging inter-dose interval on plasma aripiprazole levels and consequent D2 occupancy. We also modelled transitions from LAI medication to oral medication. Regimens were designed to afford a rate of reduction between 5 and 12.5 percentage points of D2 occupancy per month. Abrupt discontinuation of ALAI was shown to lead to a maximal D2 occupancy reduction of 16.8 percentage points per month; prolongation of the inter-dose interval of ALAI produced a slower reduction. Specifically, hyperbolic tapering was afforded by prolongation of a 400 mg ALAI inter-dose interval from 4 to 7 weeks, before reducing the dose to 300 mg ALAI. This could then be administered at up to 4-week (for 6% maximal D2 occupancy change), 6-week (9% change) or 7-week (11% change) intervals. Switching to oral medication - 5, 2.5 and 1.25 mg for the three regimens, respectively - is required for ALAI to complete full cessation to prevent too rapid a reduction in D2 occupancy. Oral medication should probably be maintained at a consistent dose for 3-6 months before further reductions to account for residual LAI being concurrently eliminated. Hyperbolic dose tapering is possible with ALAI through prolongation of the inter-dose interval and may reduce the risk of relapse compared to abrupt discontinuation of LAI medication.

Influence of antipsychotic medications on hyperlipidemia risk in patients with schizophrenia: evidence from a population-based cohort study and in vitro hepatic lipid homeostasis gene expression

Introduction

Schizophrenia increases the risk of mortality and cardiovascular disease (CVD) risk. However, the correlation between antipsychotics (APs) and CVD remains controversial. Hyperlipidemia is a significant risk factor for CVD.

Methods

We conducted a nationwide population-based retrospective cohort study to investigate the effects of APs on the risk of hyperlipidemia and lipid homeostasis gene expression. We used data from the Longitudinal Health Insurance Database of Taiwan on new-onset schizophrenia patients and a comparison cohort without schizophrenia. We used a Cox proportional hazards regression model to analyze the differences in hyperlipidemia development between the two cohorts. Furthermore, we examined the effects of APs on the hepatic expression of lipid homeostasis-related genes.

Results

After adjusting for potential interrelated confounding factors, the case group (N = 4,533) was found to have a higher hyperlipidemia risk than the control cohort (N = 4,533) [adjusted hazard ratio (aHR), 1.30, p < 0.001]. Patients with schizophrenia without APs had a significantly higher risk of hyperlipidemia (aHR, 2.16; p < 0.001). However, patients receiving APs had a significantly lower risk of hyperlipidemia than patients not receiving APs (all aHR ≤ 0.42, p < 0.001). First-generation antipsychotics (FGAs) induce the expression of hepatic lipid catabolism genes in an in vitro model.

Discussion

Patients with schizophrenia had a higher risk of hyperlipidemia than controls; however, compared with non-treated patients, AP users had a lower risk of hyperlipidemia. Early diagnosis and management of hyperlipidemia may help prevent CVD.

Cerebral blood flow in striatum is increased by partial dopamine agonism in initially antipsychotic-naïve patients with psychosis

BACKGROUND

Resting cerebral blood flow (rCBF) in striatum and thalamus is increased in medicated patients with psychosis, but whether this is caused by treatment or illness pathology is unclear. Specifically, effects of partial dopamine agonism, sex, and clinical correlates on rCBF are sparsely investigated. We therefore assessed rCBF in antipsychotic-naïve psychosis patients before and after aripiprazole monotherapy and related findings to sex and symptom improvement.

METHODS

We assessed rCBF with the pseudo-Continuous Arterial Spin Labeling (PCASL) sequence in 49 first-episode patients (22.6 ± 5.2 years, 58% females) and 50 healthy controls (HCs) (22.3 ± 4.4 years, 63% females) at baseline and in 29 patients and 49 HCs after six weeks. RCBF in striatum and thalamus was estimated with a region-of-interest (ROI) approach. Psychopathology was assessed with the positive and negative syndrome scale.

RESULTS

Baseline rCBF in striatum and thalamus was not altered in the combined patient group compared with HCs, but female patients had lower striatal rCBF compared with male patients (p = 0.009). Treatment with a partial dopamine agonist increased rCBF significantly in striatum (p = 0.006) in the whole patient group, but not significantly in thalamus. Baseline rCBF in nucleus accumbens was negatively associated with improvement in positive symptoms (p = 0.046), but baseline perfusion in whole striatum and thalamus was not related to treatment outcome.

CONCLUSIONS

The findings suggest that striatal perfusion is increased by partial dopamine agonism and decreased in female patients prior to first treatment. This underlines the importance of treatment effects and sex differences when investigating the neurobiology of psychosis.

Partial agonists of dopamine receptors: theoretical principles of combining antipsychotics including partial agonists to treat schizophrenia

Partial agonists such as aripiprazole are often used in addition to a full antagonist such as amisulpride, risperidone or olanzapine in an attempt to mitigate side-effects such as sedation, hyperprolactinaemia and weight gain. However, there can be unintended consequences, including worsening of psychosis. Moreover, previous exposure to a partial agonist may impair the subsequent response to a potent antipsychotic such as haloperidol used to control symptoms of relapse. To understand the mechanisms involved, a method is needed to compare potency in the pharmacological effects of different drugs used in combinations. This article is intended to explore and explain the theoretical principles based on the dopamine hypothesis of schizophrenia. We apply the method to analyse a recently described trial in which two full antagonists (olanzapine and amisulpride) are compared individually and in combination.

Block of Voltage-Gated Sodium Channels by Aripiprazole in a State-Dependent Manner

Aripiprazole is an atypical antipsychotic drug, which is prescribed for many psychiatric diseases such as schizophrenia and mania in bipolar disorder. It primarily acts as an agonist of dopaminergic and other G-protein coupled receptors. So far, an interaction with ligand- or voltage-gated ion channels has been classified as weak. Meanwhile, we identified aripiprazole in a preliminary test as a potent blocker of voltage-gated sodium channels. Here, we present a detailed analysis about the interaction of aripiprazole with the dominant voltage-gated sodium channel of heart muscle (hNa_v1.5). Electrophysiological experiments were performed by means of the patch clamp technique at human heart muscle sodium channels (hNa_v1.5), heterologously expressed in human TsA cells. Aripiprazole inhibits the hNa_v1.5 channel in a state- but not use-dependent manner. The affinity for the resting state is weak with an extrapolated K_r of about 55 µM. By contrast, the interaction with the inactivated state is strong. The affinities for the fast and slow inactivated state are in the low micromolar range (0.5–1 µM). Kinetic studies indicate that block development for the inactivated state must be described with a fast (ms) and a slow (s) time constant. Even though the time constants differ by a factor of about 50, the resulting affinity constants were nearly identical (in the range of 0.5 µM). Besides this, aripirazole also interacts with the open state of the channel. Using an inactivation deficit mutant, an affinity of about 1 µM was estimated. In summary, aripiprazole inhibits voltage-gated sodium channels at low micromolar concentrations. This property might add to its possible anticancer and neuroprotective properties.

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-response analysis of aripiprazole in patients with schizophrenia in Taiwan

BACKGROUND

Aripiprazole is a third-generation antipsychotic agent with acceptable efficacy and a good safety profile. Previous studies have indicated the therapeutic serum concentration of aripiprazole to be 100 to 350 ng/ml; however, most of these studies examined a Western population. Patients with schizophrenia from Tungs' Taichung MetroHarbor Hospital in central Taiwan were recruited to analyze the dose-response relationship of aripiprazole in the Chinese population.

OBJECTIVE

We aimed to investigate whether a serum concentration of aripiprazole higher than the current suggested range leads to higher response rates.

DESIGN

A prospective cohort study was designed to investigate the response rates in different studied cohorts grouped by serum concentration of aripiprazole.

DATA SOURCES AND METHODS

Data of 64 patients who presented to a single medical center in central Taiwan and who received therapeutic drug monitoring (TDM) were obtained. Serum concentrations of aripiprazole were correlated with the clinical response of patients by using the Clinical Global Impressions (CGI) scores.

RESULTS

The mean concentration of aripiprazole was 432.1 ± 275.1 ng/ml in the study cohort. Among the much-improved patients, the mean serum concentration of aripiprazole was 494 ± 273 ng/ml (25th-75th percentiles 264-666 ng/ml), which was higher than the current recommended therapeutic target of 100-350 ng/ml for aripiprazole. The response rate in the severe group (baseline CGI score of 6 or 7) was significantly higher than in the moderate group (baseline CGI score of 4 or 5; 86.7% versus 55.9%, p = 0.007).

CONCLUSION

A significantly higher response rate was observed in the study cohort with serum aripiprazole concentrations over 300 ng/ml. Therefore, dosing higher than the current recommended range may potentially improve the treatment efficacy in the Chinese population. Because the serum concentration varies among patients due to multiple intrinsic and extrinsic factors, TDM, especially in outpatients, is recommended if the clinical response is limited.

Partial agonists of dopamine receptors: mechanisms and clinical effects of aripiprazole, brexpiprazole and cariprazine

Aripiprazole, brexpiprazole and cariprazine are partial dopamine (and serotonin) agonists developed as novel antipsychotics. This article discusses their pharmacology, evidence on their licensed and off-licence uses (including psychosis, mania, bipolar depression, Tourette syndrome and autism spectrum disorder) and side-effects. In schizophrenia, they have a low risk of Parkinsonism or hyperprolactinaemia, cause modest increases in body weight and are of moderate efficacy.

Open channel block of Kv1.4 potassium channels by aripiprazole

Aripiprazole is a quinolinone derivative approved as an atypical antipsychotic drug for the treatment of schizophrenia and bipolar disorder. It acts as with partial agonist activities at the dopamine D2 receptors. Although it is known to be relatively safe for patients with cardiac ailments, less is known about the effect of aripiprazole on voltage-gated ion channels such as transient A-type K⁺ channels, which are important for the repolarization of cardiac and neuronal action potentials. Here, we investigated the effects of aripiprazole on Kv1.4 currents expressed in HEK293 cells using a whole-cell patch-clamp technique. Aripiprazole blocked Kv1.4 channels in a concentration-dependent manner with an IC₅₀ value of 4.4 μM and a Hill coefficient of 2.5. Aripiprazole also accelerated the activation (time-to-peak) and inactivation kinetics. Aripiprazole induced a voltage-dependent (δ = 0.17) inhibition, which was use-dependent with successive pulses on Kv1.4 currents without altering the time course of recovery from inactivation. Dehydroaripiprazole, an active metabolite of aripiprazole, inhibited Kv1.4 with an IC₅₀ value of 6.3 μM (p < 0.05 compared with aripiprazole) with a Hill coefficient of 2.0. Furthermore, aripiprazole inhibited Kv4.3 currents to a similar extent in a concentration-dependent manner with an IC₅₀ value of 4.9 μM and a Hill coefficient of 2.3. Thus, our results indicate that aripiprazole blocked Kv1.4 by preferentially binding to the open state of the channels.

Therapeutic drug monitoring of children and adolescents treated with aripiprazole: observational results from routine patient care

Although aripiprazole is one of the most used antipsychotics, knowledge about serum concentrations in children and adolescents is scarce and age-specific therapeutic ranges have not been established yet. Data of a routine therapeutic drug monitoring service were analyzed in order to evaluate the relationship between dose and serum concentration of aripiprazole in children and adolescents. The study also aimed to evaluate whether the therapeutic reference range defined for adults with schizophrenia (100-350 ng/ml) is applicable for minors. Data from 130 patients (aged 7-19 years) treated with aripiprazole for different indications in doses of 2-30 mg/day were evaluated. Patient characteristics, doses, serum concentrations and therapeutic outcome were assessed by standardized measures. A positive mean correlation between body weight-corrected daily dose and aripiprazole concentration was found (r_p = 0.59, p < 0.001) with variation in dose explaining 35% of the variability in serum concentrations. Girls had on average 41% higher dose-corrected concentrations than boys (244.9 versus 173.4 mg/l; p = 0.006). Aripiprazole concentrations did not vary with co-medication (p = 0.22). About 70% of all measured serum concentrations were within the recommended therapeutic range for adults. Using a calculation method in all responding patients with an ICD-10 F2 diagnosis for a rough estimation of a preliminary therapeutic window also demonstrated a similar therapeutic range of aripiprazole in minors (105.9-375.3 ng/ml) than for adults. If confirmed in larger samples and more controlled study designs, these data may contribute to the definition of a therapeutic range of aripiprazole concentrations in children and adolescents.

Monitoring and improving antipsychotic adherence in outpatient forensic diversion programs

Outpatient diversion programs present an opportunity for severely mentally ill defendants to receive psychiatric treatment and have alleged offenses dismissed by the court. Moreover, the successful completion of pretrial diversion is associated with fewer post-program arrest and jail days. The target patient population for such programs is typically people with schizophrenia spectrum disorders, but the care of such patients in outpatient settings presents challenges for monitoring treatment fidelity, specifically antipsychotic adherence, as low adherence rates are associated with increased rates of recidivism. Presented here is a review of evidence-based strategies that must be employed to track antipsychotic adherence in outpatient diversion programs, including pill counts, use of long-acting injectable antipsychotics, and determination of plasma antipsychotic levels to assess adherence and the adequacy of antipsychotic treatment. Antipsychotic therapy remains the foundation of schizophrenia treatment, but only through the use of all available modalities can clinicians maximize the odds that schizophrenia patients in pretrial diversion maintain psychiatric stability and successfully complete mental health court mandates.

Phenoconversion of CYP2D6 by inhibitors modifies aripiprazole exposure

The efficacy of aripiprazole therapy and the risk of adverse reactions are influenced by substantial inter-individual variability in aripiprazole metabolizing capacity. In vitro studies assigned the potential role in aripiprazole metabolism to CYP2D6 and CYP3A enzymes; therefore, the association between the steady-state aripiprazole plasma concentrations and patients' CYP2D6 and CYP3A statuses (CYP2D6, CYP3A4, and CYP3A5 genotypes, and CYP3A4 expression) and/or co-medication with CYP function modifying medications has been investigated in 93 psychiatric patients on stable aripiprazole therapy. The patients' CYP2D6 genotype had a major effect on aripiprazole plasma concentrations, whereas contribution of CYP3A genotypes and CYP3A4 expression to aripiprazole clearance were considered to be minor or negligible. The role of CYP3A4 expression in aripiprazole metabolism did not predominate even in the patients with nonfunctional CYP2D6 alleles. Furthermore, dehydroaripiprazole exposure was also CYP2D6 genotype-dependent. Dehydroaripiprazole concentrations were comparable with aripiprazole levels in patients with functional CYP2D6 alleles, and 35% or 22% of aripiprazole concentrations in patients with one or two non-functional CYP2D6 alleles, respectively. The concomitant intake of CYP2D6 inhibitors, risperidone, metoprolol, or propranolol was found to increase aripiprazole concentrations in patients with at least one wild-type CYP2D6*1 allele. Risperidone and 9-hydroxy-risperidone inhibited both dehydrogenation and hydroxylation of aripiprazole, whereas metoprolol and propranolol blocked merely the formation of the active dehydroaripiprazole metabolite, switching towards the inactivation pathways. Patients' CYP2D6 genotype and co-medication with CYP2D6 inhibitors can be considered to be the major determinants of aripiprazole pharmacokinetics. Taking into account CYP2D6 genotype and co-medication with CYP2D6 inhibitors may improve the outcomes of aripiprazole therapy.

Evidence-based guidelines for the pharmacological treatment of schizophrenia: Updated recommendations from the British Association for Psychopharmacology

These updated guidelines from the British Association for Psychopharmacology replace the original version published in 2011. They address the scope and targets of pharmacological treatment for schizophrenia. A consensus meeting was held in 2017, involving experts in schizophrenia and its treatment. They were asked to review key areas and consider the strength of the evidence on the risk-benefit balance of pharmacological interventions and the clinical implications, with an emphasis on meta-analyses, systematic reviews and randomised controlled trials where available, plus updates on current clinical practice. The guidelines cover the pharmacological management and treatment of schizophrenia across the various stages of the illness, including first-episode, relapse prevention, and illness that has proved refractory to standard treatment. It is hoped that the practice recommendations presented will support clinical decision making for practitioners, serve as a source of information for patients and carers, and inform quality improvement.

The Potential Utility of Aripiprazole Augmentation for Major Depressive Disorder with Mixed Features Specifier: A Retrospective Study

Objective

The present study aimed to observe potential benefit of aripiprazole augmentation in the treatment of major depressive disorder with mixed specifier (MDDM) in naturalistic treatment setting.

Methods

Data were collected from MDDM patients using a retrospective chart review for 8 weeks (week –8 and week 0) in routine practice. All patients were on current antidepressants upon starting of aripiprazole. Patients were treated without restriction of doses of aripiprazole. The primary endpoint was the mean change of Montgomery–Åsberg Depression Rating Scale (MADRS) total scores along with various secondary endpoint measures.

Results

In total 38 patients were analyzed. The changes of MADRS, Clinical Global Impression (CGI)-severity, Young Mania Rating Scale, Sheehan Disability Scale, and CGI-clinical benefit total scores from baseline to the endpoint were −7.1, −0.8, −4.9, −4.1, and −3.6, respectively (all p < 0.0001). At the endpoint, the responder and remitter rates by MADRS score criteria were approximately 32% and 21%, respectively.

Conclusion

The present findings have clearly shown the effectiveness and tolerability of aripiprazole augmentation for MDDM patients in routine practice. The present study warrants subsequent, adequately-powered, well-controlled studies for generalizability near future.

Optical Biosensors for Therapeutic Drug Monitoring

Therapeutic drug monitoring (TDM) is a fundamental tool when administering drugs that have a limited dosage or high toxicity, which could endanger the lives of patients. To carry out this monitoring, one can use different biological fluids, including blood, plasma, serum, and urine, among others. The help of specialized methodologies for TDM will allow for the pharmacodynamic and pharmacokinetic analysis of drugs and help adjust the dose before or during their administration. Techniques that are more versatile and label free for the rapid quantification of drugs employ biosensors, devices that consist of one element for biological recognition coupled to a signal transducer. Among biosensors are those of the optical biosensor type, which have been used for the quantification of different molecules of clinical interest, such as antibiotics, anticonvulsants, anti-cancer drugs, and heart failure. This review presents an overview of TDM at the global level considering various aspects and clinical applications. In addition, we review the contributions of optical biosensors to TDM.

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.

Effect of CYP2D6 genotype on exposure and efficacy of risperidone and aripiprazole: a retrospective, cohort study

BACKGROUND

The polymorphic CYP2D6 enzyme metabolises the antipsychotic drugs risperidone and aripiprazole to their active metabolites, 9OH-risperidone and dehydroaripiprazole. The aim of this study was to quantify the effect of CYP2D6 genetic variability on risperidone and aripiprazole exposure and treatment in a large patient population.

METHODS

We retrospectively obtained patient data from a routine therapeutic drug monitoring database at the Center for Psychopharmacology, Diakonhjemmet Hospital, Oslo, Norway, between Jan 1, 2005, and Oct 15, 2018. Individuals included in our analyses were CYP2D6-genotyped patients treated with risperidone or aripiprazole. Inclusion criteria for measurement of pharmacokinetic parameters (drug and metabolite serum concentrations) were oral administration of risperidone or aripiprazole, information known about prescribed daily dose and comedications, and aged older than 18 years. Exclusion criteria included polypharmacy with drugs known to be CYP2D6 inhibitors or CYP3A4 inducers or inhibitors. Treatment failure was analysed in all patients treated with risperidone or aripiprazole without these criteria. The first endpoint in our analysis was the metabolism of risperidone to 9OH-risperidone and aripiprazole to dehydroaripiprazole, estimated by the log-transformed ratio between the concentrations of metabolite and parent drug (ie, the metabolic ratio for risperidone [9OH-risperidone]/[risperidone] and the metabolic ratio for aripiprazole [dehydroaripiprazole]/[aripiprazole]). Endpoint two was measurement of drug exposure, quantified by the dose-normalised sum of parent drug and active metabolite serum concentrations (ie, active moiety). The third endpoint of treatment failure was measured as the number of patients switched from risperidone or aripiprazole to another antipsychotic drug within 1 year after the last therapeutic drug monitoring analysis of risperidone or aripiprazole. Patient subgroups were defined by CYP2D6 genotype-determined metaboliser status: poor metabolisers, intermediate metabolisers, normal metabolisers, and ultrarapid metabolisers. ANOVA was used to assess the differences in metabolic ratios, active moieties, and daily doses between individual metaboliser categories, and risperidone and aripiprazole therapeutic failures were compared by logistic regression using the normal metaboliser subgroup as a reference.

FINDINGS

1288 risperidone-treated patients and 1334 aripiprazole-treated patients were included in the study, of whom 725 (56%) risperidone-treated and 890 (67%) aripiprazole-treated patients were eligible for the pharmacokinetic analyses. CYP2D6 genotype significantly changed risperidone and aripiprazole metabolism resulting in an approximately 1·6-times and 1·4-times increase in risperidone and aripiprazole active moiety exposure in poor and intermediate metabolisers compared with normal metabolisers, respectively (odds ratios [OR] for the risperidone dose-normalised active moiety concentration 1·568, 95% CI 1·401-1·736, and 1·373, 1·213-1·532; and for the aripiprazole dose-normalised active moiety concentration 1·585, 1·447-1·724, and 1·476, 1·263-1·688, respectively; p<0·0001 for all). Compared with doses for normal metabolisers, clinicians reduced daily doses of risperidone and aripiprazole administered to poor metabolisers by 19% (95% CI 5-35, p=0·010) and 15% (95% CI 1-28, p=0·033) respectively. The incidence of switching from risperidone to another antipsychotic was increased in ultrarapid metabolisers (OR 2·934, 95% CI 1·437-5·989, p=0·003) and poor metabolisers (1·874, 1·128-3·112, p=0·015); by contrast, the incidence of switching from aripiprazole to another antipsychotic was not significantly related to CYP2D6 metaboliser status.

INTERPRETATION

CYP2D6 genotype had a substantial clinical effect on risperidone and aripiprazole exposure and on the therapeutic failure of risperidone. Pre-emptive CYP2D6 genotyping would be valuable for individualising risperidone and aripiprazole dosing and treatment optimisation.

FUNDING

H2020 program U-PGx, The Swedish Research Council, the Swedish Brain foundation, and the South-Eastern Norway Regional Health Authority.

Reduced activity and connectivity of left amygdala in patients with schizophrenia treated with clozapine or olanzapine

Obsessive-compulsive symptoms (OCS) in patients with schizophrenia are a common co-occurring condition, often associated with additional impairments. A subgroup of these patients develops OCS during treatment with second-generation antipsychotics (SGAs), most importantly clozapine and olanzapine. So far, little is known about possible neural mechanism of these SGAs, which seem to aggravate or induce OCS. To investigate the role of SGA treatment on neural activation and connectivity during emotional processing, patients were stratified according to their monotherapy into two groups (group I: clozapine or olanzapine, n = 20; group II: amisulpride or aripiprazole, n = 20). We used an fMRI approach, applying an implicit emotion recognition task. Group comparisons showed significantly higher frequency and severity of comorbid OCS in group I than group II. Task specific activation was attenuated in group I in the left amygdala. Furthermore, functional connectivity from left amygdala to right ventral striatum was reduced in group I. Reduced amygdala activation was associated with OCS severity. Recent literature suggests an involvement of an amygdala-cortico-striatal network in the pathogenesis of obsessive-compulsive disorder. The observed differential activation and connectivity pattern of the amygdala might thus indicate a neural mechanism for the development of SGA-associated OCS in patients with schizophrenia. Further neurobiological research and interventional studies are needed for causal inferences.

Serum Level Measurements Optimize Aripriprazole Treatment in Adolescent Patients

21 minors suffering from first-episode psychosis or related disorders were treated with the second-generation antipsychotic aripriprazole with serum levels being monitored over time. A significant variation of serum levels was observed in about half of the patients. Patients from Africa showed high levels of aripriprazole. In seven patients, i. e. ca. 35 % of the sample, aripriprazole treatment had to be stopped for various reasons. Therefore, serum levels of this antipsychotic (which in Germany is still considered off-label treatment before the age of 18) should be regularly monitored particularly in patients from Africa.

Long-Acting Injectable Second-Generation Antipsychotics: An Update and Comparison Between Agents

Schizophrenia is a chronic medical condition with periods of remission and relapses over a patient's lifetime. Antipsychotic medications represent the mainstay of treatment for this disease. Long-acting injectable (LAI) formulations of antipsychotics are an attractive alternative to their oral counterparts, as they enhance patient adherence. A number of second-generation antipsychotics (SGAs) are available in LAI formulations. These include paliperidone, aripiprazole, olanzapine, and risperidone. This article reviews the most recently developed and approved of these formulations-aripiprazole monohydrate, aripiprazole lauroxil, and paliperidone palmitate. While all were initially available as once-monthly formulations, a paliperidone palmitate 3-monthly injection formulation has been approved and is the first LAI agent to extend the dosing administration beyond the typical monthly time period. In addition, aripiprazole lauroxil every 6-week and 8-week administration preparations have been developed. LAI preparations of the SGAs have all demonstrated superiority over placebo and are comparable to their oral counterparts in terms of safety and tolerability, if injection site reactions are not taken into account. First-generation antipsychotic LAI preparations (e.g., haloperidol decanoate) have recently been compared with SGA LAI agents, and both formulations demonstrated comparable efficacy with the expected adverse events seen with each drug. Despite their availability, barriers to the use of LAIs remain. Education of both patients and clinicians on the use of LAI formulations and the continued development of these agents are important steps in ensuring these medications are available to the patients they would be most likely to benefit.

Antipsychotic plasma levels in the assessment of poor treatment response in schizophrenia

OBJECTIVE

Treatment resistance is a challenge for the management of schizophrenia. It is not always clear whether inadequate response is secondary to medication ineffectiveness, as opposed to medication underexposure due to non-adherence or pharmacokinetic factors. We investigated the prevalence of subtherapeutic antipsychotic plasma levels in patients identified as treatment-resistant by their treating clinician.

METHOD

Between January 2012 and April 2017, antipsychotic plasma levels were measured in 99 individuals provisionally diagnosed with treatment-resistant schizophrenia by their treating clinicians, but not prescribed clozapine. Patients were followed up to determine whether they were subsequently admitted to hospital.

RESULTS

Thirty-five per cent of plasma levels were subtherapeutic, and of these, 34% were undetectable. Black ethnicity (P = 0.006) and lower dose (P < 0.001) were significantly associated with subtherapeutic/undetectable plasma levels. Individuals with subtherapeutic/undetectable levels were significantly more likely to be admitted to hospital (P = 0.02).

CONCLUSION

A significant proportion of patients considered treatment-resistant have subtherapeutic antipsychotic plasma levels, and this is associated with subsequent admission. The presence of subtherapeutic plasma levels may suggest a need to address adherence or pharmacokinetic factors as opposed to commencing clozapine treatment. While antipsychotic levels are not recommended for the routine adjustment of dosing, they may assist with the assessment of potential treatment resistance in schizophrenia.

Converting oral to long-acting injectable antipsychotics: a guide for the perplexed

There has been increasing recognition that antipsychotic nonadherence is common across all stages of schizophrenia, starting from the first episode. Moreover, numerous meta-analyses of the existing literature indicate superiority of long-acting injectable (LAI) over oral antipsychotics when one adjusts for the greater illness severity and duration among patients in LAI antipsychotic trials. The increasing availability of LAI antipsychotic options has raised interest in converting patients from oral medication; however, the successful transition from oral to the comparable LAI antipsychotic requires an understanding of the current extent of antipsychotic exposure, the kinetics of the LAI preparation, and the expected plasma levels achieved by the LAI formulation. The purpose of this article is to provide, in a concise format, the essential information for converting patients to the LAI forms of haloperidol, fluphenazine, risperidone, paliperidone, olanzapine, and aripiprazole from the comparable oral medication, and how the use of plasma antipsychotic levels can be invaluable for this process.

Overview of systematic reviews of therapeutic ranges: methodologies and recommendations for practice

Background

Many medicines are dosed to achieve a particular therapeutic range, and monitored using therapeutic drug monitoring (TDM). The evidence base for a therapeutic range can be evaluated using systematic reviews, to ensure it continues to reflect current indications, doses, routes and formulations, as well as updated adverse effect data. There is no consensus on the optimal methodology for systematic reviews of therapeutic ranges.

Methods

An overview of systematic reviews of therapeutic ranges was undertaken. The following databases were used: Cochrane Database of Systematic Reviews (CDSR), Database of Abstracts and Reviews of Effects (DARE) and MEDLINE. The published methodologies used when systematically reviewing the therapeutic range of a drug were analyzed. Step by step recommendations to optimize such systematic reviews are proposed.

Results

Ten systematic reviews that investigated the correlation between serum concentrations and clinical outcomes encompassing a variety of medicines and indications were assessed. There were significant variations in the methodologies used (including the search terms used, data extraction methods, assessment of bias, and statistical analyses undertaken). Therapeutic ranges should be population and indication specific and based on clinically relevant outcomes. Recommendations for future systematic reviews based on these findings have been developed.

Conclusion

Evidence based therapeutic ranges have the potential to improve TDM practice. Current systematic reviews investigating therapeutic ranges have highly variable methodologies and there is no consensus of best practice when undertaking systematic reviews in this field. These recommendations meet a need not addressed by standard protocols.

Aripiprazole Once-Monthly 400 mg: Comparison of Pharmacokinetics, Tolerability, and Safety of Deltoid Versus Gluteal Administration

BACKGROUND

Two open-label, randomized, parallel-arm studies compared pharmacokinetics, safety, and tolerability of aripiprazole once-monthly 400 mg following deltoid vs gluteal injection in patients with schizophrenia.

METHODS

In the single-dose study, 1 injection of aripiprazole once-monthly 400 mg in the deltoid (n=17) or gluteal (n=18) muscle (NCT01646827) was administered. In the multiple-dose study, the first aripiprazole once-monthly 400 mg injection was administered in either the deltoid (n=71) or gluteal (n=67) muscle followed by 4 once-monthly deltoid injections (NCT01909466).

RESULTS

After single-dose administration, aripiprazole exposure (area under the concentration-time curve) was similar between deltoid and gluteal administrations, whereas median time to maximum plasma concentration was shorter (7.1 [deltoid] vs 24.1 days [gluteal]) and maximum concentration was 31% higher after deltoid administration. In the multiple-dose study, median time to maximum plasma concentration for deltoid administration was shorter (3.95 vs 7.1 days), whereas aripiprazole mean trough concentrations, maximum concentration, and area under the concentration-time curve were comparable between deltoid and gluteal muscles (historical data comparison). Multiple-dose pharmacokinetic results for the major metabolite, dehydro-aripiprazole, followed a similar pattern to that of the parent drug for both deltoid and gluteal injection sites. Safety and tolerability profiles were similar after gluteal or deltoid injections. Based on observed data, minimum aripiprazole concentrations achieved by aripiprazole once-monthly 400 mg are comparable with those of oral aripiprazole 15 to 20 mg/d.

CONCLUSIONS

The deltoid muscle is a safe alternative injection site for aripiprazole once-monthly 400 mg in patients with schizophrenia.

Psychopharmacology of Persistent Violence and Aggression

Persistent violence not due to acute psychosis or mania can be managed only after appropriate characterization of the aggressive episodes (psychotic, impulsive, or predatory/planned/instrumental). The type of violence combined with the psychiatric diagnosis dictates the evidence-based pharmacologic approaches for psychotically motivated and impulsive aggression, whereas instrumental violence mandates forensic/behavioral strategies. For nonacute inpatients, schizophrenia spectrum disorders, traumatic brain injury, and dementia comprise the majority of individuals who are persistently aggressive, with impulsive actions the most common form of violence across all diagnoses. Neurobiological considerations combined with empirical data provide a comprehensive framework for systematic medication trials to manage persistently aggressive patients.

Evaluation of the Relationship Between Pharmacokinetics and the Safety of Aripiprazole and Its Cardiovascular Effects in Healthy Volunteers

AIMS

The aim of this study was the evaluation of the possible relationship between pharmacokinetics and the safety of aripiprazole as well as its influence on blood pressure (BP), heart rate (HR), and corrected QT (QTc) interval.

METHODS

The study population comprised 157 healthy volunteers from 6 bioequivalence clinical trials. Subjects were administered a single 10-mg oral dose of each formulation separated by a 28-day washout period. Plasma concentrations were measured using high-performance liquid chromatography coupled to mass spectrometry. Blood pressure was measured at the following times: predose and 0.5, 2, 4, 6, and 8 hours postdose. An electrocardiogram was recorded at predose, 4, and 8 hours postdose.

RESULTS

Area under the curve (AUC), maximum plasma concentration, half-life, and distribution volume corrected for weight were higher in women. Aripiprazole treatment produced a decrease of BP (9.3 mm Hg on systolic and 6.2 mm Hg on diastolic pressure) and an increase in HR (12.1 beats per minute) and QTc interval (9.1 milliseconds). There were sex differences in BP, HR, and QTc interval. Women and subjects with higher AUC and maximum plasma concentration values were more prone to experience adverse drug reactions and gastrointestinal adverse reactions. The AUC was related with systolic BP and diastolic BP decrease and HR increase but there was no relationship between aripiprazole concentrations and QTc increase.

CONCLUSIONS

Aripiprazole decreases BP and increases HR and QTc interval. Pharmacokinetics, pharmacodynamics, and safety of aripiprazole are affected by sex. There is a directly proportional relationship between pharmacokinetic parameters and adverse drug reactions and effect on BP and HR.

Fast Versus Slow Strategy of Switching Patients With Schizophrenia to Aripiprazole From Other Antipsychotics

This study aimed to compare strategies differing in the speed of switching schizophrenic patients to aripiprazole from other antipsychotic agents, with dual administration for 2 weeks and then tapering off the current antipsychotic in fast (within 1 week) versus slow (within 4 weeks) strategies. This 8-week, open-label, randomized, parallel study assigned patients with a primary Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, diagnosis of schizophrenia or schizoaffective disorder to either the fast-switching (n = 38) or slow-switching (n = 41) group. Efficacy assessments at 5 time points included Positive and Negative Syndrome Scale and Clinical Global Impression scale. Safety assessments included extrapyramidal symptoms, metabolic profile, serum prolactin level, QTc interval, and adverse events. Drug concentrations and cytochrome P450 CYP2D6 and CYP3A4 genotypes were also measured. The fast- and slow-switching groups were comparable in demographical and clinical features at baseline and dropout rate. In the intention-to-treat analysis using mixed-effects models, there were significant within-group decreases over time in the Positive and Negative Syndrome Scale total scores (P = 0.03) and its subscores except for positive subscores, whereas no between-group differences were found. A reduction in body weight (P = 0.01) and lower levels of total cholesterol (P = 0.03), triglycerides (P = 0.03), and prolactin (P = 0.01) were noted in both groups but no increase in extrapyramidal symptoms or prolongation of QTc. The blood concentrations of aripiprazole in all patients were in a therapeutic range at day 56, with CYP2D6*10 polymorphisms being associated with aripiprazole concentrations. In conclusion, there is no significant difference between the fast- and slow-switching strategy in terms of improvements in clinical symptoms and metabolic profile in this 8-week study.

Antipsychotic therapeutic drug monitoring: psychiatrists' attitudes and factors predicting likely future use

BACKGROUND

This study aimed to explore predictive factors for future use of therapeutic drug monitoring (TDM) and to further examine psychiatrists' current prescribing practices and perspectives regarding antipsychotic TDM using plasma concentrations.

METHOD

A cross-sectional study for consultant psychiatrists using a postal questionnaire was conducted in north-west England. Data were combined with those of a previous London-based study and principal axis factor analysis was conducted to identify predictors of future use of TDM.

RESULTS

Most of the 181 participants (82.9%, 95% confidence interval 76.7-87.7%) agreed that 'if TDM for antipsychotics were readily available, I would use it'. Factor analysis identified five factors from the original 35 items regarding TDM. Four of the factors significantly predicted likely future use of antipsychotic TDM and together explained 40% of the variance in a multivariate linear regression model. Likely future use increased with positive attitudes and expectations, and decreased with potential barriers, negative attitudes and negative expectations. Scientific perspectives of TDM and psychiatrist characteristics were not significant predictors.

CONCLUSION

Most senior psychiatrists indicated that they would use antipsychotic TDM if available. However, psychiatrists' attitudes and expectations and the potential barriers need to be addressed, in addition to the scientific evidence, before widespread use of antipsychotic TDM is likely in clinical practice.

Adjunctive aripiprazole in the treatment of risperidone-induced hyperprolactinemia: A randomized, double-blind, placebo-controlled, dose-response study

Hyperprolactinemia is an unwanted adverse effect associated with several antipsychotics. The addition of partial dopamine receptor agonist aripiprazole may attenuate antipsychotic-induced hyperprolactinemia effectively. However, the ideal dosing regimen for this purpose is unknown. We aimed to evaluate the dose effects of adjunctive treatment with aripiprazole on prolactin levels and hyperprolactinemia in schizophrenia patients. Stable subjects 18-45 years old with schizophrenia and hyperprolactinemia (i.e., >24 ng/ml for females and >20 ng/ml for males) were randomly assigned to receive 8 weeks of placebo (n=30) or oral aripiprazole 5mg/day (n=30), 10mg/day (n=29), or 20mg/day (n=30) added on to fixed dose risperidone treatment. Serum prolactin levels were measured at baseline and after 2, 4 and 8 weeks; clinical symptoms and side effects were assessed at baseline and week 8 using the Positive and Negative Syndrome Scale, Clinical Global Impressions Severity scale, Barnes Akathisia Scale, Simpson-Angus Scale and UKU Side Effects Rating Scale. Of 119 randomized patients, 107 (89.9%) completed the 8-week study. At study end, all three aripiprazole doses resulted in significantly lower prolactin levels (beginning at week 2), higher response rates (≥30% prolactin reduction) and higher prolactin normalization rates than placebo. Effects were significantly greater in the 10 and 20mg/day groups than the 5mg/day group. No significant changes were observed in any treatment groups regarding psychopathology and adverse effect ratings. Adjunctive aripiprazole treatment was effective and safe for resolving risperidone-induced hyperprolactinemia, producing significant and almost maximal improvements by week 2 without significant effects on psychopathology and side effects.

Increased orbitofrontal cortex activation associated with "pro-obsessive" antipsychotic treatment in patients with schizophrenia

BACKGROUND

Patients with schizophrenia have an approximately 10-fold higher risk for obsessive-compulsive symptoms (OCS) than the general population. A large subgroup seems to experience OCS as a consequence of second-generation antipsychotic agents (SGA), such as clozapine. So far little is known about underlying neural mechanisms.

METHODS

To investigate the role of SGA treatment on neural processing related to OCS in patients with schizophrenia, we stratified patients according to their monotherapy into 2 groups (group I: clozapine or olanzapine; group II: amisulpride or aripiprazole). We used an fMRI approach, applying a go/no-go task assessing inhibitory control and an n-back task measuring working memory.

RESULTS

We enrolled 21 patients in group I and 19 patients in group II. Groups did not differ regarding age, sex, education or severity of psychotic symptoms. Frequency and severity of OCS were significantly higher in group I and were associated with pronounced deficits in specific cognitive abilities. Whereas brain activation patterns did not differ during working memory, group I showed significantly increased activation in the orbitofrontal cortex (OFC) during response inhibition. Alterations in OFC activation were associated with the severity of obsessions and mediated the association between SGA treatment and co-occurring OCS on a trend level.

LIMITATIONS

The main limitation of this study is its cross-sectional design.

CONCLUSION

To our knowledge, this is the first imaging study conducted to elucidate SGA effects on neural systems related to OCS. We propose that alterations in brain functioning reflect a pathogenic mechanism in the development of SGA-induced OCS in patients with schizophrenia. Longitudinal studies and randomized interventions are needed to prove the suggested causal interrelations.

Measuring adherence to medication in schizophrenia: the relationship between attitudes toward drug therapy and plasma levels of new-generation antipsychotics

BACKGROUND

Nonadherence to medication is still a major problem in the treatment of schizophrenia. The current longitudinal study investigated whether the patients' attitudes toward treatment correlated with the ratio of observed vs expected plasma levels of antipsychotic drugs as an objective measurement of adherence.

METHODS

Data of patients starting monotherapy with a new-generation antipsychotic were collected 2, 4, and 12 weeks after the initiation of treatment. Next to the assessment of patients' attitudes toward medication by means of the Drug Attitude Inventory, the ratio of the observed vs expected plasma level was calculated. Antipsychotic-induced side effects were evaluated by means of the Udvalg for Kliniske Undersogelser Side Effect Rating Scale.

RESULTS

A total of 93 patients were eligible for statistical analysis. About one-half of the ratios of observed vs expected plasma levels ranged from 0.5 to 2 and were considered normal, whereas the other ratios were considered either too low (<0.5) or too high (>2). No consistent correlation between patients' attitude toward drug therapy and the individual ratios of observed vs expected plasma levels of medication was detected. This finding was not affected by side effects.

CONCLUSIONS

Our results highlight the importance of recognizing the complex nature of adherence to medication in schizophrenia patients. Importantly, we found no consistent correlation between subjective and objective measures of medication adherence. Therefore, monitoring adherence to medication remains a challenge in clinical practice.

[Plasma levels of antipsychotics and the severity of side-effects in the treatment of schizophrenia exacerbation]

OBJECTIVE

To study a relationship between plasma levels of antipsychotics (AP) and severity of side-effects (SE) during the treatment of inpatients with exacerbation of schizophrenia.

MATERIAL AND METHODS

The study included 39 patients treated with risperidone, haloperidol, zuclopenthixol, clozapine, aripiprazole or olanzapine as monotherapy or in combination of two AP. Blood sampling to measure the AP plasma level was performed twice (at 7-10 and 26-30 day from start of treatment), the levels of prolactin and glucose were determined once (at 26-30 day from start of treatment). Patients were assessed by psychometric scales PANSS and NSA and the side-effects scale UKU.

RESULTS

The increased concentration of AP was noted in 33% of the patients. The high concentration of AP was significantly associated with akathisia and hyperkinesia (by UKU scale), NSA retardation factor and hyperprolactinemia. Patients with severe hyperprolactinemia were twice as likely to have a clinically significant depression. Increased blood glucose levels were observed in 18% of the patients, there was no significant association with AP plasma levels. Mental SE were most prominent, with a drift towards the neurological SE in the group with higher AP plasma levels. Chlorpromazine equivalent didn't significantly differ in the groups with normal, high and low AP concentrations.

CONCLUSION

Elevated AP plasma levels, which were associated with some clinically significant SE and some negative symptoms, were found in most patients. In this regard, therapeutic drug monitoring is a promising method for the individualization of schizophrenia exacerbation treatment in routine clinical practice.

Aripiprazole: from pharmacological profile to clinical use

Clinical experience with aripiprazole has confirmed the effectiveness and the safety of this novel antipsychotic drug in patients with schizophrenia as well as for the treatment of mania in type I bipolar disorder. However the generalization of the results from clinical trials requires further effort in order to address some issues and to overcome incorrect and partial interpretation of the clinical evidence. This article provides some straightforward guidance that may help clinical psychiatrists to translate the mechanism of action of aripiprazole into clinical setting, thus improving the appropriate use of the drug through rational application of its pharmacological profile. Examples of paradigmatic clinical situations are presented and discussed, suggesting possible intervention strategies, which may contribute to achieving the most appropriate use of the pharmacological properties of aripiprazole in real life settings.

Effects of switching from olanzapine to aripiprazole on the metabolic profiles of patients with schizophrenia and metabolic syndrome: a double-blind, randomized, open-label study

BACKGROUND

Patients with schizophrenia suffer high rates of metabolic derangements on some antipsychotic medications that predispose them to cardiovascular diseases. Keeping this fact in mind, we planned this open-label study to see the effect on various metabolic parameters after switching stable schizophrenia subjects, who had developed metabolic syndrome on olanzapine, to aripiprazole.

METHODS

Sixty-two patients with schizophrenia who were stable on olanzapine and were fulfilling modified National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP-III) criteria for the presence of metabolic syndrome were enrolled on the study. Patients were randomly assigned either to switch to aripiprazole or to stay on olanzapine, on a 1:1 basis. Cross-tapering over a period of 1 month was done while switching patients to aripiprazole. Laboratory assessment for metabolic parameters was done at baseline, 8 weeks, and 24 weeks after enrollment; efficacy assessment was done using the Positive and Negative Syndrome Scale (PANSS) at baseline and 24 weeks, the Clinical Global Impressions severity subscale (CGI-S) at baseline, and the Clinical Global Impressions improvement subscale (CGI-I) at 24 weeks.

RESULTS

All parameters of metabolic syndrome (waist circumference, blood pressure, triglyceride level, fasting blood glucose, and high-density lipoprotein cholesterol) kept deteriorating in the stay group, compared with a continuous improvement in the switch group over time. At the end of the study, 26 patients (100%) from the stay group and 15 patients (42.8%) from switch group met the modified NCEP ATP-III criteria for presence of metabolic syndrome (P<0.001). There were no statistically significant differences between groups in psychopathology changes as measured by the PANSS total score and CGI-I scores.

CONCLUSION

Clinically stable patients with schizophrenia who are taking olanzapine and who have evidence of metabolic syndrome can be successfully switched to aripiprazole, with improvement in various parameters of metabolic syndrome and without any significant change in efficacy measures.

Antipsychotic treatment modulates glutamate transport and NMDA receptor expression

Schizophrenia patients often suffer from treatment-resistant cognitive and negative symptoms, both of which are influenced by glutamate neurotransmission. Innovative therapeutic strategies such as agonists at metabotropic glutamate receptors or glycin reuptake inhibitors try to modulate the brain's glutamate network. Interactions of amino acids with monoamines have been described on several levels, and first- and second-generation antipsychotic agents (FGAs, SGAs) are known to exert modulatory effects on the glutamatergic system. This review summarizes the current knowledge on effects of FGAs and SGAs on glutamate transport and receptor expression derived from pharmacological studies. Such studies serve as a control for molecular findings in schizophrenia brain tissue and are clinically relevant. Moreover, they may validate animal models for psychosis, foster basic research on antipsychotic substances and finally lead to a better understanding of how monoaminergic and amino acid neurotransmissions are intertwined. In the light of these results, important differences dependent on antipsychotic substances, dosage and duration of treatment became obvious. While some post-mortem findings might be confounded with multifold drug effects, others are unlikely to be influenced by antipsychotic treatment and could represent important markers of schizophrenia pathophysiology. In similarity to the convergence of toxic and psychotomimetic effects of dopaminergic, serotonergic and anti-glutamatergic substances, the therapeutic mechanisms of SGAs might merge on a yet to be defined molecular level. In particular, serotonergic effects of SGAs, such as an agonism at 5HT1A receptors, represent important targets for further clinical research.

Perinatal use of aripiprazole: plasma levels, placental transfer, and child outcome in 3 new cases

The use of new agents of second-generation antipsychotics in childbearing women is increasing and poses an unknown risk to the fetus; thus, information of pregnancy and child outcome are urgently needed. We reviewed the literature of 12 patients, 3 of them were exposed during the first trimester, and added 3 new cases of peripartum use of aripiprazole. No teratogenesis was observed despite all 3 women having received the substance during part or full first trimester. All 3 pregnancies were uncomplicated with spontaneous birth. Dosage had to be changed during the course of gestation from 2.5 to 15 mg and plasma levels (PL) were below recommended levels, although all 3 women remained in stable remission throughout pregnancy and postpartum period.The extent of placental transfer of aripiprazole (mean ratio of 56.2%) is comparable with that of other second-generation antipsychotics.Our observations have clinical implications: antipsychotic PLs show large-scale decreases, which may require dose adjustments during pregnancy. Pregnant women may require lower PLs. In our cases, a PL of one third of the previous effective PL was effective and safe. Repeated therapeutic drug monitoring during late gestation based on individual, previous effective PLs seems to be a feasible way for safe and effective antipsychotic therapy in unplanned pregnancy.

Serum concentrations of risperidone and aripiprazole in subgroups encoding CYP2D6 intermediate metabolizer phenotype

BACKGROUND

Cytochrome P450 2D6 intermediate metabolizer phenotype (CYP2D6 IM) comprises various genotype subgroups. The aim of this study was to evaluate serum concentrations of the CYP2D6 substrates risperidone and aripiprazole in psychiatric patients with various CYP2D6 genotypes encoding IM phenotype.

METHODS

The study was based on therapeutic drug monitoring data from CYP2D6-genotyped patients (mainly of white origin) treated with orally administered risperidone (n = 190) or aripiprazole (n = 266). Patients were divided into 3 genotype subgroups encoding IM phenotype: (1) heterozygous carriers of fully functional and nonfunctional variant alleles (*1/def), (2) homozygous carriers of reduced-function variant alleles (red/red), and (3) heterozygous carriers of reduced-function and nonfunctional variant alleles (def/red). Dose-adjusted serum concentrations of risperidone and aripiprazole were compared between the genotype subgroups using *1/def, the most frequent CYP2D6 genotype among these subgroups, as the reference group.

RESULTS

Median serum concentrations were 4.5- and 1.6-fold higher in the def/red genotype than the *1/def genotype for risperidone and aripiprazole, respectively (P < 0.01 for both). Correspondingly, the serum concentrations were 3.4- and 1.8-fold higher in the red/red subgroup compared with the reference group (P < 0.05 for both).

CONCLUSIONS

In conclusion, this study revealed substantial variability in serum concentrations of risperidone and aripiprazole between CYP2D6 genotypes associated with IM phenotype. A considerable phenotypical difference was observed between patients carrying 1 and 2 variant alleles.

Aripiprazole in an animal model of chronic alcohol consumption and dopamine D₂ receptor occupancy in rats

BACKGROUND

Epidemiologic studies and clinical assessment of schizophrenic population have revealed a high incidence of overlap between schizophrenia and addictive disorders.

OBJECTIVE

The aim of the present investigation was to study the effect of aripiprazole in a preclinical animal model of chronic alcohol self-administration (CASA) and also to evaluate the influence of CASA on plasma pharmacokinetics and dopamine D₂ receptor (D₂R) occupancy in rats.

METHODS

The effect of oral administration of aripiprazole (1, 3, and 10 mg/kg) on 4% alcohol intake in CASA was studied for a period of 45 min after a post-dosing interval of 60 min. Brain penetration, pharmacokinetics, and D₂R occupancy of aripiprazole were evaluated in normal and CASA rats.

RESULTS

Aripiprazole reduced alcohol consumption in CASA rats by 13, 28, and 86% at 1, 3, and 10 mg/kg, respectively, and the effect reached statistical significance at 10 mg/kg (p < .01). At this behavioral effective dose, a decrease (75%) in total plasma apparent clearance and an increase in oral area under the concentration-time curve (3.98-fold) and bioavailability (3.50-fold) of aripiprazole was observed in CASA rats. Striatal D₂R occupancy and brain exposure of aripiprazole were significantly higher (∼twofold) in CASA rats when compared to normal rats (p < .01).

CONCLUSION

Chronic alcohol intake results in a significant increase in exposure of aripiprazole in plasma and brain and striatal D₂R occupancy.

SCIENTIFIC SIGNIFICANCE

Chronic alcohol intake would increase aripiprazole exposure, thus aripiprazole dose might have to be decreased (assuming this same phenomenon occurs in humans).