Pharmacokinetic profile of the extended-release formulation of quetiapine fumarate (quetiapine XR): clinical implications

Acute Quetiapine Intoxication: Relationship Between Ingested Dose, Serum Concentration and Clinical Presentation-Structured Literature Review and Analysis

Over the past decade, quetiapine has become one of the most commonly used psychotropic drugs in acute intoxication events worldwide. A structured literature review and analysis were conducted to assess the relationship between the kinetic and dynamic profiles in acute quetiapine intoxication. The correlation between dose and peak serum concentration (cmax) was determined using Pearson's correlation coefficient. Binary logistic regression was used to evaluate dose and cmax as predictors of the most common clinical events, signs and symptoms. One hundred and thirty-four cases of acute quetiapine ingestion were included in the analysis, with a median ingested dose of 10 g and a median cmax of 4 mg/L. The typical half-life was estimated to be 16.5 h, significantly longer than at therapeutic doses. For the immediate-release formulation, a biphasic disposition could not be excluded. Dose and cmax demonstrated a weak but significant correlation (r = 0.256; N = 63; p = 0.043). Central nervous system depression and tachycardia were the most common clinical signs. Higher doses and concentrations increased the risk of severe intoxication and were good predictors of intubation, tachycardia, hypotension, QTc prolongation and seizures, but not QRS prolongation, arrhythmia, heart block, hypokalaemia or acidosis. The thresholds for dose and cmax that increased the risk for individual signs and symptoms varied widely. However, doses > 3 g or cmax > 2 mg/L can be considered as alert levels that represent a high risk for severe clinical course of acute quetiapine intoxication.

Pharmacokinetic interaction of quetiapine and lamotrigine - victim and perpetrator?

OBJECTIVE

We aimed to investigate the ambiguous findings of earlier research regarding the reduction of quetiapine plasma levels when combined with lamotrigine, most likely via UDP-glucuronosyltransferase induction by lamotrigine.

METHODS

One thousand one hundred and fifty samples, divided into four groups of patients receiving either quetiapine immediate- (IR) or extended-release (XR) without or in combination with lamotrigine were compared regarding absolute and dose-adjusted plasma concentrations. Furthermore, samples of intra-individual controls were analyzed.

RESULTS

Patients receiving quetiapine IR in combination with lamotrigine showed 31% lower plasma (p = 0.002) and 23% lower dose-adjusted plasma concentrations (p = 0.004) compared to those receiving IR monotherapy. The proportion of patients with quetiapine plasma concentrations below the lower limit of the therapeutic reference range was 50% and 30% in the combination group and in patients receiving monotherapy, respectively (p = 0.03). However, no significant differences regarding plasma concentration (p = 0.13) and dose-adjusted plasma concentration (p = 0.42) were observed in patients with combination vs. monotherapy with the XR formulation of quetiapine. In the intra-individual controls, no trends could be identified, possibly due to insufficient number of samples (p > 0.05).

CONCLUSIONS

The combination of quetiapine IR with lamotrigine is associated with significantly lower drug concentrations of quetiapine, potentially impacting quetiapine effectiveness. For quetiapine ER, a significant interaction is less likely.

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

BACKGROUND

Being one of the most widespread, pervasive, and troublesome illnesses in the world, depression causes dysfunction in various spheres of individual and social life. Regrettably, despite obtaining evidence-based antidepressant medication, up to 70% of people are going to continue to experience troublesome symptoms. Quetiapine, as one of the most commonly prescribed antipsychotic medication worldwide, has been reported as an effective augmentation strategy to antidepressants. The right quetiapine dose and personalized quetiapine treatment are frequently challenging for clinicians. This study aimed to identify important influencing variables for quetiapine dose by maximizing the use of data from real world, and develop a predictive model of quetiapine dose through machine learning techniques to support selections for treatment regimens.

METHODS

The study comprised 308 depressed patients who were medicated with quetiapine and hospitalized in the First Hospital of Hebei Medical University, from November 1, 2019, to August 31, 2022. To identify the important variables influencing the dose of quetiapine, a univariate analysis was applied. The prediction abilities of nine machine learning models (XGBoost, LightGBM, RF, GBDT, SVM, LR, ANN, DT) were compared. Algorithm with the optimal model performance was chosen to develop the prediction model.

RESULTS

Four predictors were selected from 38 variables by the univariate analysis (p < 0.05), including quetiapine TDM value, age, mean corpuscular hemoglobin concentration, and total bile acid. Ultimately, the XGBoost algorithm was used to create a prediction model for quetiapine dose that had the greatest predictive performance (accuracy = 0.69) out of nine models. In the testing cohort (62 cases), a total of 43 cases were correctly predicted of the quetiapine dose regimen. In dose subgroup analysis, AUROC for patients with daily dose of 100 mg, 200 mg, 300 mg and 400 mg were 0.99, 0.75, 0.93 and 0.86, respectively.

CONCLUSIONS

In this work, machine learning techniques are used for the first time to estimate the dose of quetiapine for patients with depression, which is valuable for the clinical drug recommendations.

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.

Comparative efficacy of quetiapine by dose and formulation for psychosis in schizophrenia: A systematic review and dose-response model-based network meta-analysis

BACKGROUND

Quetiapine has varied dose ranges and immediate-(QTP-IR) and extended-release (QTP-ER) formulations.

AIMS

We hypothesized that QTP-IR is inferior to QTP-ER at any dose in efficacy for the acute treatment in schizophrenia and tested using a dose-response model-based network meta-analysis (NMA).

METHODS

We searched PubMed, the Cochrane Library, CINHAL, and ClinicalTrials.gov for randomized placebo-controlled trials comparing QTP-IR and/or QTP-ER for acute psychosis in patients with schizophrenia up to September 21, 2022. A random effect Bayesian dose-response model-based NMA was performed to compare the dose-response relationships between QTP-IR and QTP-ER.

RESULTS

The relationship between doses and antipsychotic effects was partially bell-shaped for QTP-IR but not for QTP-ER. The respective peak effect dose was 279.7 mg for QTP-IR and 557.2 mg for QTP-ER, with no significant difference in peak effect. QTP-IR ranging from 100 to 300 mg were significantly superior to QTP-ER at the same doses. In addition, QTP-IR ranging from 100 to 400 mg were significantly better than placebo, whereas QTP-ER ranging from 500 to 800 mg were significantly more effective than placebo. Moreover, QTP-IR 600 mg was significantly less effective than QTP-ER at the same dose. Furthermore, QTP-IR 700 mg was significantly superior to placebo, but significantly inferior to QTP-ER 600 mg.

CONCLUSIONS

QTP-IR may reach comparable peak responses and exhibit enhanced antipsychotic effects at lower doses than QTP-ER; the converse may be true at relatively high doses. Collectively, we propose a novel strategy to enhance the efficacy of QTP administration.

IVIVC for Extended Release Hydrophilic Matrix Tablets in Consideration of Biorelevant Mechanical Stress

Purpose

When establishing IVIVC, a special problem arises by interpretation of averaged in vivo profiles insight of considerable individual variations in term of time and number of mechanical stress events in GI-tract. The objective of the study was to investigate and forecast the effect of mechanical stress on in vivo behavior in human of hydrophilic matrix tablets.

Methods

Dissolution profiles for the marketed products were obtained at different conditions (stirring speed, single- or repeatable mechanical stress applied) and convoluted into C-t profiles. Vice versa, published in vivo C-t profiles of the products were deconvoluted into absorption profiles and compared with dissolution profiles by similarity factor.

Results

Investigated hydrophilic matrix tablets varied in term of their resistance against hydrodynamic stress or single stress during the dissolution. Different scenarios, including repeatable mechanical stress, were investigated on mostly prone Seroquel® XR 50 mg. None of the particular scenarios fits to the published in vivo C-t profile of Seroquel® XR 50 mg representing, however, the average of individual profiles related to scenarios differing by number, frequency and time of contraction stress. When different scenarios were combined in different proportions, the profiles became closer to the original in vivo profile including a burst between 4 and 5 h, probably, due to stress-events in GI-tract.

Conclusion

For establishing IVIVC of oral dosage forms susceptible mechanical stress, a comparison of the deconvoluted individual in vivo profiles with in vitro profiles of different dissolution scenarios can be recommended.

Approach to Evaluating QT Prolongation of Quetiapine Fumarate in Late Stage of Clinical Development Using Concentration-QTc Modeling and Simulation in Japanese Patients With Bipolar Disorder

PURPOSE

Quetiapine has been reported to prolong the QT interval, and has been used as a positive control in thorough QT studies. The objective of the present study was to evaluate, in the late stages of clinical development, the QT-prolongation effects of the extended-release (XR) formulation of quetiapine at the approved dose in Japanese patients with bipolar disorder, using concentration-QT modeling and simulation.

METHODS

Plasma concentrations of quetiapine and 4 of its metabolites (M1, M2, M4, and M5), and the QT interval corrected using the Fridericia formula (QTcF), were used for the concentration-QT analysis. Data from intensive electrocardiogram monitoring at predose and at 4, 6, 10, and 24 h after the administration of the last dose were pooled from a Phase I trial (6949-CL-0006) and from sparse sampling in late-stage clinical trials (6949-CL-0005, -0021, -0022, and -0023) in Japanese patients (N = 505). The upper limit of 1-sided 95% confidence interval (CI) of the changes from baseline in QTcF (ΔQTcF) at the geometric mean Cmax of a therapeutic dose of 300 mg once daily was predicted using a linear mixed-effects model, with the intercept as a random effect specifying a subject effect.

FINDINGS

For quetiapine and M2, but not M1, M4, or M5, positive slopes were observed between ΔQTcF and concentration. The predicted upper limits of the 1-sided 95% CIs did not exceed the regulatory threshold of 10 msec. Therefore, QTc prolongation is unlikely to be clinically relevant at the approved dose of quetiapine XR.

IMPLICATIONS

In this pooled data analysis of the QT-prolongation effects of the quetiapine XR, positive relationships between ΔQTcF and quetiapine and M2 concentrations were observed. However, the predicted upper limits of the 1-sided 95% CIs did not exceed 10 msec. Therefore, QTc prolongation is unlikely to be clinically relevant at the approved dose. ClinicalTrials.gov identifiers: NCT01725282, NCT01919008, NCT01725308, NCT01737268, and NCT02362412.

Population Pharmacokinetics Analysis of Quetiapine Extended-release Formulation in Japanese Patients with Bipolar Depression

PURPOSE

The objectives of this study were to explore covariates of plasma quetiapine concentrations after oral administration of quetiapine extended-release formulation (XR), and to examine the exposure-response relationship in Japanese patients with bipolar depression, using population pharmacokinetics (PopPK) modeling.

METHODS

In a multicenter, randomized, double-blind, placebo-controlled study of quetiapine XR in patients with bipolar depression, plasma for the measurement of quetiapine concentration was collected at weeks 2, 4, 8, 12, 20, 28, and 52 during oral administration of 150 or 300 mg once daily of quetiapine XR before bedtime. A PopPK model of quetiapine XR was developed using nonlinear mixed-effects modeling with first-order conditional estimation with interactions. The exposure-response relationship was examined using post-hoc exposures. The post-hoc AUC estimate was plotted against the change in the Montgomery-Åsberg Depression Rating Scale (ΔMADRS) total score from baseline to 8 weeks following once-daily doses at 300 mg.

FINDINGS

The final PopPK analysis dataset contained 322 patients and 1162 observations (cutoff data at week 28; cutoff date, February 2016). The plasma quetiapine concentration-time profile in patients with bipolar depression after oral administration of quetiapine XR was represented well using a 1-compartment with first-order absorption model. Covariate analysis led to the selection of γ-glutamyl transpeptidase on apparent oral clearance and body weight on apparent volume of distribution as covariates. The final population mean values of apparent oral clearance and apparent volume of distribution were 87.7 L/h and 277 L, respectively, and the interindividual %CVs were 32.6% and 75.0%, respectively.

IMPLICATIONS

The effects of covariates on PK parameters were not large compared with the interindividual variability. In addition, there was no clear relationship between the AUC and ΔMADRS. ClinicalTrials.gov identifier: NCT01725308.

Efficacy and Safety of Quetiapine for Pediatric Bipolar Depression: A Systematic Review of Randomized Clinical Trials

Quetiapine is a second-generation antipsychotic (SGA) approved by the Food and Drug Administration (FDA) for the treatment of schizophrenia, mania, and aggression in children and adolescents. It is also commonly used as an off-label medication to treat children and adolescents with bipolar depression, although the FDA has not approved quetiapine for this purpose. We conducted a systematic review of randomized clinical trials (RCTs) using the MEDLINE database and included two studies that met our inclusion criteria. Both RCTs were eight-week short-term studies that involved patients of 10-18 years of age with a Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) diagnosis of bipolar disorder, depressed type. The mean difference in the Children's Depression Rating Scale-Revised (CDRS-R) score and the response and remission rates in the quetiapine group were not statistically significant when compared to the placebo group. A high placebo response rate proved that quetiapine was no better than the placebo in treating pediatric bipolar depression. Quetiapine proved to be a relatively safe drug with the most common side effects being headache, somnolence, gastric upset, and weight gain. There was a significant increase in triglyceride levels, but no other metabolic effects were reported. This calls for future studies with larger sample sizes and improved methodology to explore the efficacy of quetiapine and other SGAs for the management of pediatric bipolar depression.

Observational assessment of safety in seroquel (OASIS): a specialist cohort event monitoring (SCEM) study in England

BACKGROUND

This study was designed to monitor the short-term (up to 12 weeks) use and safety of quetiapine (Seroquel) extended release (XL) and quetiapine immediate release (IR) prescribed to patients with a clinical diagnosis of schizophrenia, and/or manic episodes associated with bipolar disorder by psychiatrists under normal conditions of use.

METHODS

A Specialist Cohort Event Monitoring (SCEM) study was conducted in England February 2010-April 2013. This observational cohort study recruited patients prescribed quetiapine XL within the secondary care setting by psychiatrists. A reference cohort of quetiapine IR users was also recruited. Baseline and 12 week observational data were collected from psychiatrists who abstracted information from medical records onto bespoke questionnaires. Data were collected on demographics, indication, past medical history, prescribing information and events of interest. Summary descriptive statistics were calculated.

RESULTS

The final cohort consisted of 869 eligible patients; 646 XL users and 223 IR users. The majority of XL and IR users were female (56.2% and 55.6%, respectively), with a median age of 40 (interquartile range [IQR]: 29, 49) and 39 (IQR: 28, 50) years, respectively. The most frequent indication for treatment was Manic episodes associated with Bipolar Affective disorder (53.4% XL and 49.8% IR). Median index dose was 200 mg/day (IQR: 100, 300) for XL users and 50 mg/day (IQR: 50, 100) for IR users, while median final maintenance dose was 400mg/day (IQR: 250, 600) and 300 mg/day (IQR: 100, 400), respectively. The most frequently reported event of interest in both cohorts was sedation (n = 151, 23.9% XL cohort and n = 49, 23.0% IR cohort).

CONCLUSION

Utilisation of quetiapine XL appeared to be in line with prescribing guidelines in terms of dose, and commonly reported events of interest were in concordance with the known safety profile. Overall, this SCEM study provided important information on the safety and utilisation of quetiapine XL in the secondary care setting in England.

Potential Utility of Biased GPCR Signaling for Treatment of Psychiatric Disorders

Tremendous advances have been made recently in the identification of genes and signaling pathways associated with the risks for psychiatric disorders such as schizophrenia and bipolar disorder. However, there has been a marked reduction in the pipeline for the development of new psychiatric drugs worldwide, mainly due to the complex causes that underlie these disorders. G-protein coupled receptors (GPCRs) are the most common targets of antipsychotics such as quetiapine and aripiprazole, and play pivotal roles in controlling brain function by regulating multiple downstream signaling pathways. Progress in our understanding of GPCR signaling has opened new possibilities for selective drug development. A key finding has been provided by the concept of biased ligands, which modulate some, but not all, of a given receptor's downstream signaling pathways. Application of this concept raises the possibility that the biased ligands can provide therapeutically desirable outcomes with fewer side effects. Instead, this application will require a detailed understanding of the mode of action of antipsychotics that drive distinct pharmacologies. We review our current understanding of the mechanistic bases for multiple signaling modes by antipsychotics and the potential of the biased modulators to treat mental disorders.

Relationship between the timing of relapse and plasma drug levels following discontinuation of cariprazine treatment in patients with schizophrenia: indirect comparison with other second-generation antipsychotics after treatment discontinuation

OBJECTIVE

To explore the timing of relapse following drug discontinuation and its relationship to estimated plasma levels and elimination half-life by comparing data from a randomized, placebo-controlled discontinuation study of cariprazine with those from similarly designed and conducted randomized control trials of other oral atypical antipsychotics (AAPs).

METHODS

Data from a long-term, randomized, double-blind, placebo-controlled relapse prevention study in participants with schizophrenia (NCT01412060) were analyzed. Similarly designed, published studies of other AAPs were used for comparison. Time to drug-placebo relapse separation and relapse rates were estimated from Kaplan-Meier curves and evaluated descriptively. Separation was defined as a sustained difference of ≥5% incidence of relapse between the AAP and placebo curves.

RESULTS

The Kaplan-Meier curve for cariprazine showed a time to drug-placebo relapse separation at 6-7 weeks after randomization, compared to the Kaplan-Meier curves for the other AAPs, which showed earlier separation at 1-4 weeks. The placebo relapse rates at 4 weeks after randomization were 5% for cariprazine and 8-34% for other AAPs. Geometric mean values of model-predicted plasma concentrations for total active cariprazine moieties (sum of cariprazine, desmethyl-cariprazine, and didesmethyl-cariprazine) were 20.0 and 6.1 nM at 2 and 4 weeks after discontinuation, respectively. Elimination half-lives of other AAPs and their active metabolites (<4 days) suggest that plasma concentrations would be low or negligible at 2-4 weeks after last dose.

CONCLUSION

Discontinuation of cariprazine treatment appeared to be associated with a delayed incidence of relapse compared with other AAPs, which may be due to the longer half-life of cariprazine and its active metabolites.

Bioequivalence of two quetiapine extended release tablets in Chinese healthy volunteers under fasting and fed conditions and effects of food on pharmacokinetic profiles

Objective

The objectives of this study were to evaluate the bioequivalence of Quesero extended release (Quesero XR) tablets and Seroquel extended release (Seroquel XR) tablets under fasting and fed conditions and to determine the effect of food on the pharmacokinetic (PK) properties of Quesero XR or Seroquel XR in Chinese healthy volunteers.

Methods

A single-site, randomized, open-label, two-period crossover design with a 10-day washout period was conducted in 20 subjects under the fed and fasting studies. A single oral dose of 200 mg Quesero XR or Seroquel XR was given to the subjects after an overnight fast of 10 hours. Blood samples were taken at scheduled time spots from 0 hour pre dose to 36 hours post dose. Plasma concentrations of quetiapine were measured by a validated ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method. The PK parameters were calculated by non-compartment analysis using Phoenix WinNonlin software.

Results

On both conditions, no significant differences were found among the main PK parameters of the two preparations by analysis of variance (P>0.05); the Wilcoxon test of maximum peak plasma concentration (T_max) showed no significant differences (P>0.05); the 90% confidence limit (CL) of lnC_max, lnAUC_0→36, and lnAUC_0→∞ fell within the acceptable range of 80%–125%. As compared with the fasting state, the T_max was advanced and the mean maximum plasma concentration (C_max), AUC_0→36, and AUC_0→∞ were also increased in the fed state; the geometric mean ratio and 90% CI of the main PK parameters fell outside the range of the CIs; analysis of variance showed significant differences in the other PK parameters except for apparent total clearance after oral administration (clearance rate; P<0.05).

Conclusion

The two formulations of Quesero XR and Seroquel XR are bioequivalent under both fasting and fed conditions, and food may affect the PK profiles by increasing the rate and extent of absorption of Quesero XR or Seroquel XR in Chinese healthy volunteers.

Is There a Potential of Misuse for Quetiapine?: Literature Review and Analysis of the European Medicines Agency/European Medicines Agency Adverse Drug Reactions' Database

PURPOSE/BACKGROUND

A recent years' increase in both prescribing and availability of second-generation antipsychotics (SGAs) has been observed. According to the literature, typically made up by case studies/series, quetiapine seems to be the most commonly misused SGA, with both intranasal and intravenous intake modalities having been described. Another SGA that has been anecdotally reported to be misused is olanzapine. For these molecules, both a previous history of drug misuse and being an inmate have been described as factors associated with misuse. Hence, while providing here an updated literature review of the topic, we aimed at assessing all cases of quetiapine misuse/abuse/dependence/withdrawal as reported to the European Medicines Agency's EudraVigilance (EV) database; this was carried out in comparison with the reference drug olanzapine.

METHODS

All spontaneous, European Medicines Agency database reports relating to both quetiapine (2005-2016) and olanzapine (2004-2016) misuse/abuse/dependence/withdrawal issues were retrieved, and a descriptive analysis was performed.

RESULTS

From the EV database, 18,112 (8.64% of 209,571) and 4178 (7.58% of 55,100) adverse drug reaction reports of misuse/abuse/dependence/withdrawal were associated with quetiapine and olanzapine, respectively. The resulting proportional reporting ratio values suggested that the misuse/abuse-, dependence-, and withdrawal-related adverse drug reactions were more frequently reported for quetiapine (1.07, 1.01, and 5.25, respectively) in comparison with olanzapine.

CONCLUSIONS

Despite data collection limitations, present EV data may suggest that, at least in comparison with olanzapine, quetiapine misuse may be a cause for concern.

A thorough QT study to evaluate the QTc prolongation potential of two neuropsychiatric drugs, quetiapine and escitalopram, in healthy volunteers

Prolongation of the QT interval on an ECG is a surrogate marker for predicting the proarrhythmic potential of a drug under development. The aim of this study was to evaluate the QTc prolongation potential of two neuropsychiatric drugs, quetiapine immediate release (IR) and escitalopram, in healthy individuals. This was a randomized, open-label, 4×4 Williams crossover study, with four single-dose treatments [placebo, 400 mg moxifloxacin (positive control), 20 mg escitalopram, and 100 mg quetiapine IR], conducted in 40 healthy volunteers. Serial blood samples for pharmacokinetics and ECG were collected. Individually, RR-corrected QTc intervals (QTcI) and placebo-adjusted changes from baseline values of QTcI (ΔΔQTcI) were evaluated. Lower-bound values of the one-sided 95% confidence interval for ΔΔQTcI of moxifloxacin with more than 5 ms confirmed the sensitivity of the assay. The maximum upper bound 95% confidence interval for the ΔΔQTcI of quetiapine IR and escitalopram was 13.7 and 10.5 ms, with mean estimates of 10.2 and 6.9 ms, respectively. Peak effects of moxifloxacin and quetiapine IR on ΔΔQTcI were observed at approximately time to maximum concentration (Tmax), whereas that of escitalopram was observed 3 h after Tmax. The concentration-ΔΔQTcI relationships of quetiapine IR and escitalopram were relatively flat, as compared with that of moxifloxacin. The results demonstrated the validity of trial methodology and that quetiapine IR and escitalopram caused QT prolongation in healthy individuals. In addition, hysteresis of escitalopram-induced QTc prolongation. These results indicate that higher doses of these drugs could lead to greater QT prolongation in a dose-response manner.

Utilisation of extended release quetiapine (Seroquel XL™): Results from an observational cohort study in England

BACKGROUND

A post-authorisation safety study was carried out as part of the EU Risk Management Plan to examine the long-term (up to 12 months) use of quetiapine XL as prescribed in general practice in England.

AIM

To present a description of the drug utilisation characteristics of quetiapine XL.

METHODS

An observational, population-based cohort design using the technique of Modified Prescription-Event Monitoring (M-PEM). Patients were identified from dispensed prescriptions issued by general practitioners (GPs) for quetiapine XL between September 2008 and February 2013. Questionnaires were sent to GPs 12 months following the 1st prescription for each individual patient, requesting drug utilisation information. Cohort accrual was extended to recruit additional elderly patients (special population of interest). Summary descriptive statistics were calculated.

RESULTS

The final M-PEM cohort consisted of 13,276 patients; median age 43 years (IQR: 33, 55) and 59.0% females. Indications for prescribing included bipolar disorder (n=3820), MDD (n=2844), schizophrenia (n=2373) and other (non-licensed) indications (n=3750). Where specified, 59.3% (7869/13,276) were reported to have used quetiapine IR (immediate release formulation) previously at any time. The median start dose was highest for patients with schizophrenia (300 mg/day [IQR 150, 450]). The final elderly cohort consisted of 3127 patients and 28.5% had indications associated with dementia. The median start dose for elderly patients was highest for patients with schizophrenia or BD (both 100mg/day [IQR 50, 300]).

CONCLUSIONS

The prevalence of off-label prescribing in terms of indication and high doses was common, as was use in special populations such as the very elderly. Whilst off-label use may be unavoidable in certain situations, GPs may need to re-evaluate prescribing in circumstances where there may be safety concerns. This study demonstrates the ongoing importance of observational studies such as M-PEM to gather real-world clinical data to support the post-marketing benefit:risk management of new medications, or existing medications for which license extensions have been approved.

Population pharmacokinetic modeling of quetiapine after administration of seroquel and seroquel XR formulations to Western and Chinese patients with schizophrenia, schizoaffective disorder, or bipolar disorder

A population model describing quetiapine pharmacokinetics (PK) in Western and Chinese patients following oral administration of immediate-release (IR) and extended-release (XR) formulations was developed using plasma concentrations in 127 patients from 5 studies with quetiapine IR and/or XR in Western patients and 1 study with quetiapine XR in Chinese patients. A 1-compartmental model with first-order absorption and first-order elimination adequately described the quetiapine PK. The typical apparent volume of distribution and elimination rate constant of quetiapine were 574 L and 0.12 h(-) (1) , respectively. The estimated population absorption rate constants were 1.46 and 0.10 h(-1) for quetiapine IR and XR, respectively. Covariate analysis revealed that race was not a significant covariate influencing the PK of quetiapine. Simulation conducted with the final quetiapine population PK model predicted that the administration of a 200-mg twice-daily dose of quetiapine IR in Chinese patients would achieve a steady-state AUC (AUCss ) ± standard deviation of 3087 ± 1480 ng · h/mL, which is in close agreement with the reported value (3538 ± 1728 ng · h/mL). The model also predicted that once-daily administration of 300 mg quetiapine IR or XR would achieve similar exposure in terms of AUCss in Chinese patients.

Pharmacotherapy of bipolar disorder with quetiapine: a recent literature review and an update

Bipolar disorder is a chronic, recurrent condition with the usual onset during adolescence or early adulthood. In the Diagnostic and Statistical Manual of Mental Disorders 5th edition, it is conceptualized as a spectrum disorder usually associated with such comorbidities as anxiety disorders and substance use disorders. It is a relatively prevalent condition often complicated by mixed episodes, rapid cycling, subsyndromal symptoms, and treatment refractoriness. In spite of carrying substantial morbidity and mortality, effective treatments are few and far between and conventional mood stabilizers are often unsuccessful in controlling the various manifestations of the disorder. In this scenario, second generation antipsychotics are emerging as treatments with valid efficacy in all phases of bipolar disorder. Quetiapine is a versatile atypical antipsychotic which was first approved for the treatment of schizophrenia, but latter on the basis of controlled studies earned United States Food and Drug Administration’s approval for acute as well as maintenance treatment of this difficult to treat condition. In this review, recently published studies in the last 10 years were examined to update the knowledge about the efficacy and safety of quetiapine in the treatment of bipolar disorder. The medication’s clinical pharmacology was first considered followed by a literature review summarizing its uses in bipolar disorder. The conclusion was that quetiapine was efficacious in manic, mixed and depressive episodes and as a maintenance agent with a good tolerability profile.

Subtherapeutic serum quetiapine concentrations after absorption inhibition by binding resins: a case report

WHAT IS KNOWN AND OBJECTIVE

Polystyrene sulfonate and sevelamer are binding resins that are used in the treatment of, respectively, hyperkalemia and hyperphosphatemia. It is unknown whether these resins interact with the antipsychotic quetiapine.

CASE SUMMARY

We report on a woman with unexplainable low serum quetiapine concentrations who also used the binding resins polystyrene sulfonate and sevelamer. An In vitro binding assay showed binding of quetiapine by these resins. Separation of the ingestion times of quetiapine and the binding resins resulted in increased serum levels in this patient.

WHAT IS NEW AND CONCLUSION

Polystyrene sulfonate and sevelamer are able to bind quetiapine. Healthcare professionals should be aware of this potential drug-drug interaction as this could lead to antipsychotic treatment failure.

Development of physiologically based pharmacokinetic model to evaluate the relative systemic exposure to quetiapine after administration of IR and XR formulations to adults, children and adolescents

Quetiapine is an atypical antipsychotic drug with a high permeability, moderate solubility and defined as a Biopharmaceutics Classification System class ll compound. The pharmacokinetics (PK) of the quetiapine immediate-release (IR) formulation has been studied in both adults and children, but the quetiapine extended-release (XR) formulation has only been conducted in adults. The purpose of the current study was to use physiologically based pharmacokinetic modeling (PBPK) quantitatively to predict the PK of the XR formulation in children and adolescents. Using a 'learn and confirm' approach, PBPK models were developed employing in vitro ADME and physicochemical data, clinical PK data of quetiapine IR/XR in adults and clinical PK data of quetiapine IR in children. These models can predict well the effects of CYP3A4 inhibition and induction on the PK of quetiapine, the PK profile of quetiapine IR in children and adults, and the PK profile of quetiapine XR in adults. The AUC and Cmax ratios (children vs adults) for the different age groups were in reasonable agreement with the observed ratios. In addition, the PBPK model predicted that children and adolescents are likely to achieve a similar exposure following administration of either the XR formulation once daily or the IR formulation twice daily at similar total daily doses. The results from the study can help inform dosing regimens in pediatrics using the quetiapine XR formulation.

Antipsychotic dosing: found in translation

In the field of schizophrenia research, as in other areas of psychiatry, there is a sense of frustration that greater advances have not been made over the years, calling into question existing research strategies. Arguably, many purported gains claimed by research have been "lost in translation," resulting in limited impact on diagnosis and treatment in the clinical setting. There are exceptions; for example, we would argue that different lines of preclinical and clinical research have substantially altered how we look at antipsychotic dosing. While this story remains a work in progress, advances "found in translation" have played an important role. Detailing these changes, the present paper speaks to a body of evidence that has already shifted clinical practice and raises questions that may further alter the manner in which antipsychotics have been administered over the last 6 decades.