Comparative Physicochemical and Pharmacokinetic Properties of Quetiapine and Its Active Metabolite Norquetiapine.

Quetiapine (QTP) is an atypical antipsychotic drug commonly used to treat several psychiatric disorders and is metabolized into the active metabolite norquetiapine (NQTP). This study was designed to evaluate and compare the physicochemical properties, metabolic stability, brain distribution, and pharmacokinetics of QTP and NQTP. Compared to QTP, NQTP had a higher pKa, solubility, and rat liver microsomal stability, optimal log D and similar log P values. For pharmacokinetic evaluation, QTP and NQTP were administered orally and intravenously to rats at various doses. The plasma QTP and NQTP concentrations in rats were determined by a fully-validated liquid-chromatography tandem mass spectrometry (LC-MS/MS). Over the investigated dosing range, both QTP and NQTP showed linear pharmacokinetics. Following oral administration of the same dose, the area under the concentration-time curve (AUC0-∞) and maximum serum concentration (Cmax) were larger after NQTP administration compared to QTP administration. In addition, NQTP had a greater absolute oral bioavailability compared to QTP (15.6% vs. 0.63%, respectively). The brain-to-plasma concentration ratio was greater after NQTP administration compared to the QTP and NQTP ratios after QTP administration. NQTP administration results in increased systemic exposure and brain distribution compared to QTP administration. Future studies are needed to evaluate the pharmacologic and toxicologic effects of increased NQTP exposures.

Influence of ABCB1 and CYP3A5 genetic polymorphisms on the pharmacokinetics of quetiapine in healthy volunteers.

BACKGROUND AND OBJECTIVES: Quetiapine is an atypical antipsychotic drug used to treat schizophrenia and acute episodes of mania. Quetiapine is metabolized by CYP3A enzymes including CYP3A5 and is a substrate of P-glycoprotein, an efflux drug transporter encoded by the ABCB1 gene. We assessed the effects of ABCB1 [c.1236C>T (rs1128503), c.2677G>T/A (rs2032582), c.3435C>T (rs1045642)] and CYP3A5*3 (6986A>G) (rs776746) polymorphisms on the pharmacokinetics of quetiapine in humans. MATERIALS AND METHODS: Forty healthy male individuals were enrolled, and their ABCB1 and CYP3A5 polymorphisms were assessed. After a single dose of 100 mg quetiapine was administered, plasma concentrations of quetiapine were measured for 24 h and pharmacokinetic analysis was carried out. RESULTS: The ABCB1 polymorphisms including c.1236C>T, c.2677G>T/A, and c.3435C>>T did not affect plasma levels of quetiapine, and its pharmacokinetic parameters did not differ among ABCB1 genotype groups. However, the CYP3A5*3 polymorphism significantly affected the plasma level of quetiapine and its pharmacokinetics. The peak plasma concentration of quetiapine was 208.39 ng/ml for CYP3A5*1/*1, 243.46 ng/ml for CYP3A5*1/*3, and 332.94 ng/ml for CYP3A5*3/*3 (P=0.0118). The mean AUC(inf) (area under the time vs. concentration curve from 0 to infinity) value was 627.3, 712.77, and 1045.29 ng h/ml, respectively (P=0.0017). CONCLUSION: The results indicated that the genetic polymorphism of CYP3A5*3 but not ABCB1 significantly influences the plasma level of quetiapine and its pharmacokinetics. These findings suggest that the CYP3A5 genetic polymorphism affects the disposition of quetiapine and provide a plausible explanation for interindividual variation in the disposition of this drug.

Quetiapine and aripiprazole signal differently to ERK, p90RSK and c-Fos in mouse frontal cortex and striatum: role of the EGF receptor.

BACKGROUND: Signaling pathways outside dopamine D2 receptor antagonism may govern the variable clinical profile of antipsychotic drugs (APD) in schizophrenia. One postulated mechanism causal to APD action may regulate synaptic plasticity and neuronal connectivity via the extracellular signal-regulated kinase (ERK) cascade that links G-protein coupled receptors (GPCR) and ErbB growth factor signaling, systems disturbed in schizophrenia. This was based upon our finding that the low D2 receptor affinity APD clozapine induced initial down-regulation and delayed epidermal growth factor receptor (EGFR or ErbB1) mediated activation of the cortical and striatal ERK response in vivo distinct from olanzapine or haloperidol. Here we map whether the second generation atypical APDs aripiprazole and quetiapine affect the EGFR-ERK pathway and its substrates p90RSK and c-Fos in mouse brain, given their divergent agonist and antagonist properties on dopaminergic transmission, respectively. RESULTS: In prefrontal cortex, aripiprazole triggered triphasic ERK phosphorylation that was EGFR-independent but had no significant effect in striatum. Conversely quetiapine did not alter cortical ERK signaling but elevated striatal ERK levels in an EGFR-dependent manner. Induction of ERK by aripiprazole did not affect p90RSK signaling but quetiapine decreased RSK phosphorylation within 1-hour of administration. The transcription factor c-Fos by comparison was a direct target of ERK phosphorylation induced by aripiprazole in cortex and quetiapine in striatum with protein levels in temporal alignment with that of ERK. CONCLUSIONS: These data indicate that aripiprazole and quetiapine signal to specific nuclear targets of ERK, which for quetiapine occurs via an EGFR-linked mechanism, possibly indicating involvement of this system in its action.

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.

A thorough QTc study of 3 doses of iloperidone including metabolic inhibition via CYP2D6 and/or CYP3A4 and a comparison to quetiapine and ziprasidone.

The potential for iloperidone, a D2/5-HT2A antipsychotic, to affect the heart rate-corrected QT interval (QTc) was assessed in the absence and presence of metabolic inhibitors in a randomized, open-label, multicenter study. QT interval prolongation by medications, including both conventional and atypical antipsychotic drugs, can predispose patients to cardiac arrhythmias and result in sudden death. Adults with schizophrenia or schizoaffective disorder and normal electrocardiograms at baseline (N = 188) were randomized 1:1:1:1:1 to iloperidone, 8 mg twice daily (BID), 12 mg BID, 24 mg once daily (QD); quetiapine, 375 mg BID; or ziprasidone, 80 mg BID during period 1 (no metabolic inhibitors present). Iloperidone BID produced mean changes in QTc Fridericia correction (QTcF) interval (8.5-9.0 milliseconds [ms]) similar to those produced by ziprasidone (9.6 ms) and higher than those produced by quetiapine (1.3 ms). Iloperidone, 24 mg QD, produced a mean QTcF change of 15.4 ms. Coadministration of metabolic inhibitors with iloperidone during periods 2 (paroxetine) and 3 (paroxetine and ketoconazole) resulted in greater increases in the QTc interval. Increased QTc was observed in individuals with specific cytochrome P450 2D6 polymorphisms. Up to 10% of patients on iloperidone experienced QTc intervals of 60 ms or longer in the presence of metabolic inhibition and QD dosing. However, no patients experienced QTc changes of clinical concern (QTc ≥ 500 ms). The most common adverse events with iloperidone were headache, anxiety, and dyspepsia. The only cardiovascular adverse events with iloperidone were non-concentration-dependent tachycardia that was mild in most patients and did not lead to further sequelae. Pharmacogenetics and recommendations are discussed.

Quetiapine and norquetiapine serum concentrations and clinical effects in depressed patients under augmentation therapy with quetiapine.

BACKGROUND: Quetiapine has been recently approved as an add-on therapy in the treatment of major depressive disorders in the case of inadequate response to antidepressant monotherapy. Thereby the antidepressant potential is attributed to the N-demethylated metabolite norquetiapine (NQ). The aim of this cross-sectional analysis was to relate quetiapine (Q) doses to serum concentrations of Q and its active metabolite and clinical effects. METHODS: Data were obtained from patients who had been treated with different antidepressants and augmented under naturalistic conditions with Q for whom blood level measurements were requested. RESULTS: For this analysis, 105 depressed patients were included who had been augmented with Q. The mean daily doses of Q were 222 ± 125 mg. Doses correlated significantly (P < 0.001) with the highly variable serum concentrations of both Q and NQ. Median serum concentrations of Q and NQ were 46 ng/mL (25th to 75th percentile 20-91 ng/mL) and 59 ng/mL (25th to 75th percentile 26-133 ng/mL), respectively. Concentrations per dose ranged from 0.10 to 0.58 ng·ml·mg for Q and from 0.17 to 0.59 ng·ml·mg for NQ. Most patients (55%) received comedications in addition to the antidepressant drug and Q. According to the clinical global impressions scale, 60% of the patients were either much (36%) or very much improved (24%). Receiver-operating characteristic analysis revealed no significant differences of serum concentrations between responders and nonresponders for NQ (P = 0.835) but a trend for Q (P = 0.056). CONCLUSIONS: Due to marked variability of Q and NQ concentrations in the blood, therapeutic drug monitoring may be helpful to identify pharmacokinetic peculiarities. The lack of correlation between serum concentrations of NQ and clinical improvement casts doubts on the concept that NQ is the pharmacologically active principle for the augmentation therapy.

Comparison of D2 dopamine receptor occupancy after oral administration of quetiapine fumarate immediate-release and extended-release formulations in healthy subjects.

Quetiapine is an established drug for treatment of schizophrenia, bipolar disorder, and major depressive disorder. While initially manufactured as an immediate-release (IR) formulation, an extended-release (XR) formulation has recently been introduced. Pharmacokinetic studies show that quetiapine XR provides a lower peak and more stable plasma concentration than the IR formulation. This study investigated if the pharmacokinetic differences translate into different time curves for central D2 dopamine receptor occupancy. Eleven control subjects were examined with positron emission tomography (PET) and the radioligand [11C]raclopride. Eight subjects underwent all of the scheduled PET measurements. After baseline examination, quetiapine XR was administered once-daily for 8 d titrated to 300 mg/d on days 5-8, followed by 300 mg/d quetiapine IR on days 9-12. PET measurements were repeated after the last doses of quetiapine XR and IR at predicted times of peak and trough plasma concentrations. Striatal D2 receptor occupancy was calculated using the simplified reference tissue model. Peak D2 receptor occupancy was significantly higher with quetiapine IR than XR in all subjects (50 ± 4% and 32 ± 11%, respectively), consistent with lower peak plasma concentrations for the XR formulation. Trough D2 receptor occupancy was similarly low for both formulations (IR 7 ± 7%, XR 8 ± 6%). The lower peak receptor occupancy associated with quetiapine XR may explain observed pharmacodynamic differences between the formulations. Assuming that our findings in control subjects are valid for patients with schizophrenia, the study supports the view that quetiapine, like the prototype atypical antipsychotic clozapine, may show antipsychotic effect at lower D2 receptor occupancy than typical antipsychotics.

Possible drug-drug interaction between quetiapine and lamotrigine--evidence from a Swedish TDM database.

AIM: The aim of the present study was to investigate a previously proposed interaction between quetiapine and lamotrigine resulting in reduced serum quetiapine concentrations. METHODS: Data on 402 patients subjected to analysis of quetiapine concentration in serum were extracted from a routine therapeutic drug monitoring database. Among these patients, those concomitantly treated with lamotrigine (n= 22) were identified and matched with 22 controls receiving quetiapine while unexposed to lamotrigine. The dose-corrected quetiapine concentrations (C : D ratios) in the two groups were compared in both paired and unpaired analyses. RESULTS: Patients co-treated with lamotrigine had a lower mean C : D ratio (0.71, 95% CI 0.46, 0.97) compared with controls (1.64, 95% CI 1.00, 2.28). Dose-corrected quetiapine concentrations were 58% lower in patients co-medicated with lamotrigine. CONCLUSIONS: This study indicates that lamotrigine exposure is associated with substantially reduced serum concentrations of quetiapine, possibly due to induced glucuronidation. These findings need to be confirmed in experimental studies.

Pharmacokinetic variability of quetiapine and the active metabolite N-desalkylquetiapine in psychiatric patients.

BACKGROUND: Quetiapine is an atypical antipsychotic drug that was recently also approved for the treatment of uni- and bipolar depression. The antidepressive response is considered to be mediated by the metabolite N-desalkylquetiapine, and the aim of this study was to assess the interindividual pharmacokinetic variability of quetiapine and N-desalkylquetiapine in psychiatric patients based on therapeutic drug monitoring samples. METHODS: Serum measurements of quetiapine and N-desalkylquetiapine performed between October 2007 and July 2008 were retrospectively included from a routine therapeutic drug monitoring database. Pharmacokinetic variability was expressed as the 5-95 percentile range in dose-adjusted serum concentrations (C/D ratios). The impact of age (65 years or older), gender, and sampling time on the C/D ratios was studied by linear mixed model analysis. Samples from patients comedicated with CYP3A4 inducers or inhibitors were examined separately. RESULTS: In total, 927 serum samples from 601 patients were included (all using quetiapine immediate-release tablets). The 5-95 percentiles of the C/D ratio ranged 15-fold (0.14-2.1 nmol/L/mg) for quetiapine and fivefold (0.44-2.1 nmol/L/mg) for N-desalkylquetiapine. Elderly (65 years or older) obtained 1.5- and 1.2-fold higher C/D ratios of quetiapine (P = 0.002) and N-desalkylquetiapine (P = 0.03) compared with younger patients, respectively. Sampling time was also found to significantly affect the C/D ratios of quetiapine (P = 0.001), whereas gender was not a significant variable (P > 0.13). In three patients treated with potent CYP3A4 inducers, the observed C/D ratios of quetiapine and N-desalkylquetiapine were 77% and 11% lower than the mean C/D ratio in the study population, respectively. CONCLUSION: The pharmacokinetic variability was greater for quetiapine compared with N-desalkylquetiapine. Age 65 years or older and comedication with CYP3A4 inducers affected the serum levels of both agents, but the relative impact was greater on quetiapine.

Quetiapine in adolescents with non-affective psychotic disorders: an open-label trial.

INTRODUCTION: There is a need for more studies on the clinical effectiveness, tolerability and pharmacokinetics of atypical antipsychotics in adolescents with psychotic disorders, as this represents a vulnerable and difficult population to treat. According to recent concerns regarding disabling side effects of antipsychotics, particularly weight gain, further monitoring of their safety profiles is needed. This situation prompted the authors to carry out an investigation on the clinical effectiveness of quetiapine in psychotic adolescents. METHODS: 23 adolescents (13-18 years old) with psychotic disorders participated in a 12-week open label trial, including 6 visits assessing clinical efficacy, tolerability and safety of quetiapine (50-750 mg daily). RESULTS: Adolescents were treated with lower doses compared to adults. Significant decreases in CGI and PANSS total scores were observed after both 4 and 12 weeks of quetiapine treatment compared to baseline. Sedation was the main adverse effect, but medication was generally well tolerated. Irregular compliance, (as assessed by pill counts, a questionnaire and by plasma quetiapine concentration monitoring), and alcohol and/or cannabis consumption were factors identified in this study which add to the difficulty in treating this population. DISCUSSION: The results of the present study help to consolidate evidence of the usefulness of quetiapine as a treatment for adolescents with psychotic disorders. However, this study also highlights the issues encountered in treating this group, including the presence of comorbidities such as drug abuse.

Individual clearance and therapeutic drug monitoring of quetiapine in clinical practice.

OBJECTIVE: Quetiapine is one of the most frequent prescribed antipsychotics. Based on the consensus guidelines of therapeutic drug monitoring (TDM) in clinical practice, TDM of Quetiapine is "useful". In this pilot study, using a natural sample, we investigated the influence of co-medication, age and gender on the serum concentrations and clearance of Quetiapine. Also we compared the individual clearance in our sample with the expected clearance for healthy subjects, obtained in controlled studies. METHODS: 150 blood samples were collected anonymously under clinical conditions, Quetiapine trough serum levels were determined using HPLC. Additional information about gender, age, co-medication and dosage was obtained. RESULTS: There was a significant, positive, but weak correlation between daily dose and serum levels of Quetiapine (r=0.44; p=0.01). When Carbamazepine was co-administered, the clearance was significantly higher (p=0.01). 83% of the serum levels were outside the therapeutic range, only 28% were within the expected clearance. CONCLUSIONS: In addition to the therapeutic range the individual clearance related to the expected clearance may help to optimize individual pharmacotherapy, especially for combination therapy or in case of incompliance or abnormal metabolism.

Prolonged delirium after quetiapine overdose.

Quetiapine is an atypical antipsychotic agent increasingly used to treat schizophrenia and bipolar disorder in pediatric patients. Few published data exist concerning quetiapine's effects in therapeutic settings or short-term overdose in pediatric and adolescent populations. In this report, we describe a 15-year-old adolescent girl who experienced continued delirium 5 days after an overdose of quetiapine, trazodone, and clonidine. The patient initially presented with sedation and stable vital signs. After 3 days of gradual improvement, she experienced episodes of delirium coinciding with an increase in resting heart rate. On the basis of suspicion for quetiapine-associated antimuscarinic effects, the patient was administered intravenously with physostigmine on the fifth day after ingestion. Treatment resulted in a brief resolution of symptoms. Serum quetiapine levels measured 1 day and 5 days after ingestion were 3400 and 4800 ng/mL, respectively. The use of physostigmine and interpretation of serum levels are discussed further.

Distribution of quetiapine and metabolites in biological fluids and tissues.

Quetiapine is an atypical antipsychotic drug, frequently found in post-mortem samples. The quantitative determination of active metabolites may help in the interpretation of the potential toxic effects of the parent drug and its role in death. A fully validated LC-MS/MS method was developed for the identification and quantification of quetiapine and two main metabolites (N-desalkylquetiapine and 7-hydroxyquetiapine) in blood, biological fluids and tissues. Then, the distribution of analytes in different matrices was evaluated. LODs of 0.9, 0.3 and 0.3ng/mL were calculated for quetiapine, N-desalkylquetiapine and 7-hydroxyquetiapine respectively; while a LOQ at the concentration of 10.0ng/mL was defined for the three analytes. 13 post-mortem positive real cases have been included in the experiment. The results revealed that quetiapine and N-desalkylquetiapine might undergo a significant post-mortem redistribution, while 7-hydroxyquetiapine is less affected by this factor. N-desalkylquetiapine could be found in blood in relatively high concentrations in comparison to those of quetiapine; therefore, it should be always advisable to measure both the analytes. The analysis of tissues could provide additional data on potential intoxication with quetiapine.

Metabolism of quetiapine by CYP3A4 and CYP3A5 in presence or absence of cytochrome B5.

The antipsychotic drug quetiapine is extensively metabolized by CYP3A4, but little is known about the possible influence of the polymorphic enzyme CYP3A5. This in vitro study investigated the relative importance of CYP3A4 and CYP3A5 in the metabolism of quetiapine and compared the metabolic pattern by the two enzymes, in the presence or absence of cytochrome b(5). Intrinsic clearance (CL(int)) of quetiapine was determined by the substrate depletion approach in CYP3A4 and CYP3A5 insect cell microsomes with or without coexpressed cytochrome b(5). Formation of the metabolites quetiapine sulfoxide, N-desalkylquetiapine, O-desalkylquetiapine, and 7-hydroxyquetiapine by CYP3A4 and CYP3A5 were compared in the different microsomal preparations. CL(int) of quetiapine by CYP3A5 was less than 35% relative to CYP3A4. CL(int) was higher (3-fold) in CYP3A4 microsomes without cytochrome b(5) compared with CYP3A4 microsomes with coexpressed cytochrome b(5), whereas in CYP3A5 microsomes CL(int) was similar for both microsomal preparations. Metabolism of quetiapine by CYP3A5 revealed a different metabolic pattern compared with CYP3A4. The results indicated that O-desalkylquetiapine constituted a higher proportion of the formed metabolites by CYP3A5 compared with CYP3A4. In conclusion, the present study indicates that CYP3A5 is of minor importance for the overall metabolism of quetiapine, regardless of the presence of cytochrome b(5). However, a different metabolic pattern by CYP3A5 compared with CYP3A4 could possibly result in different pharmacological and/or toxicological effects of quetiapine in patients expressing CYP3A5.

Quetiapine extended release: in schizophrenia.

Quetiapine is an atypical antipsychotic agent with well established efficacy and tolerability in the acute and maintenance treatment of adults with schizophrenia. The extended-release formulation of quetiapine (quetiapine XR) was developed to provide more convenient once-daily administration, as well as allowing simple and rapid dose escalation, with the aim of improving compliance (known to be a substantial issue in patients with schizophrenia). In several short-term clinical trials, oral quetiapine XR 400-800 mg once daily was generally effective across a range of symptoms in the acute treatment of schizophrenia. As a long-term maintenance treatment, quetiapine XR prevented relapse in patients with stable disease, with significantly longer times to relapse in patients treated with quetiapine XR compared with placebo. Quetiapine XR was generally well tolerated in clinical trials. According to pooled results from three 6-week trials, events occurring in >or=5% of quetiapine XR recipients with an incidence>or=2-fold that seen in placebo recipients were dry mouth, somnolence and dizziness. A generally low incidence of extrapyramidal symptoms (EPS) is seen in quetiapine XR recipients. The most common potentially EPS-associated adverse events seen with quetiapine treatment were akathisia, restlessness and tremor. Rates of worsening of Simpson-Angus Scale and Barnes Akathisia Rating Scale scores were not dissimilar among quetiapine XR, quetiapine immediate release and placebo.

Self-reported sedation profile of immediate-release quetiapine fumarate compared with extended-release quetiapine fumarate during dose initiation: a randomized, double-blind, crossover study in healthy adult subjects.

OBJECTIVES: The primary study objective was to assess the time course and intensity of sedation after administration of immediate-release (IR) and extended-release (XR) quetiapine fumarate in healthy subjects during dose initiation. The tolerability of the 2 formulations was also evaluated. METHODS: This was a randomized, double-blind, double-dummy, 2-period crossover study in healthy adult (age 18-50 years) subjects. It employed the dose-initiation schedule used in studies of the 2 quetiapine formulations in patients with bipolar depression: 50 mg on day 1, 100 mg on day 2, 200 mg on day 3, and 300 mg on days 4 and 5. Doses were administered in the morning. The primary end point was the level of sedation 1 hour after dosing on day 1, as rated by subjects using a visual analog scale (VAS) ranging from 0 = alert to 100 = drowsy. Secondary VAS end points included sedation over a 14-hour period on day 1, and on days 2 through 5. Blood was drawn on day 5 of both periods for determination of plasma drug concentrations by a liquid chromatography method with tandem mass-spectrometric detection. Adverse events (AEs) were recorded throughout the study. RESULTS: Sixty-three subjects were enrolled in the study, comprising the safety population. The perprotocol population consisted of 58 subjects (79.0% male, 21.0% female; 67.2% black, 24.1% white; mean age, 31.8 years; mean weight, 80.7 kg). One hour after dosing on day 1, sedation was significantly greater with quetiapine IR than with quetiapine XR (mean VAS score, 33.2 vs 11.3, respectively; P < 0.001). There were no significant differences in sedation between formulations at 7 hours after dosing (64.5 and 53.6), 8 hours after dosing (46.9 and 50.8), or 14 hours after dosing (both, 12.7). On day 1, numerically more subjects had a VAS score>75 (substantial sedation) 1 hour after dosing in the quetiapine IR group than in the quetiapine XR group (14 vs 4 subjects). On day 5, the mean (95% CI) quetiapine C(max) for the IR and XR formulations was 689.19 (605.83-784.02) and 381.70 (341.40-426.76) ng/mL; the mean was AUC(0-11) was 2835.89 (2517.92-3194.02) and 2515.21 (2281.76--2772.55) ng . h/mL; and the median T(max) was 2.0 and 5.0 hours. The incidence of any AEs was 21.7% with quetiapine IR and 9.8% with quetiapine XR. CONCLUSION: In these healthy subjects, quetiapine XR was associated with a lower intensity of self-reported sedation compared with quetiapine IR. ClinicalTrials.gov Identifier: NCT00702676; Astra Zenecaclinicaltrials.com Identifier: D1443C00033.

Pharmacokinetic profiles of extended release quetiapine fumarate compared with quetiapine immediate release.

This 10-day, single-center, open-label, randomized, crossover study compared pharmacokinetic profiles and tolerability of extended release quetiapine fumarate (quetiapine XR) with quetiapine immediate release (quetiapine IR) in patients with schizophrenia, schizoaffective disorder or bipolar disorder. After a 2-day lead-in period during which patients received quetiapine XR 300 mg once daily, patients were randomized to quetiapine IR 150 mg twice daily followed by quetiapine XR 300 mg once daily, or quetiapine XR 300 mg once daily followed by quetiapine IR 150 mg twice daily. Pharmacokinetic parameters were evaluated at the end of each 4-day treatment period at steady state. Vital signs, laboratory values, and adverse events (AEs) were recorded throughout the study. The least squares means (90% confidence interval) of the ratio of the area under the plasma concentration-time curve over a 24 h dosing interval (AUC ([0-24 h])) for quetiapine XR/IR was 1.04 (0.92-1.19) and within the pre-defined range set for equivalence (0.80-1.25). Maximum plasma concentration at steady state (C(max)) was approximately 13% lower for quetiapine XR than for quetiapine IR (495.3 versus 568.1 ng/mL), time to reach C(max) (t(max)) was 5 h versus 2 h and mean concentration at the end of 24 h dosing interval (C(min)) was 95.3 versus 96.5 ng/mL, respectively. No patients withdrew from the study owing to AEs and there were no serious AEs or deaths related to study medication. No unexpected AEs, changes in vital signs or laboratory values were observed. These findings suggest that modifying the formulation does not change the overall absorption or elimination of quetiapine, and support emerging clinical evidence for the use of quetiapine XR as a once daily treatment in patients initiating therapy or those established on quetiapine IR.

Safety and efficacy of quetiapine in bipolar depression.

OBJECTIVE: To review the clinical data investigating the efficacy and safety of quetiapine in bipolar depression. DATA SOURCES: Searches of MEDLINE and PubMed (1977-July 2009) were conducted using the key words quetiapine and bipolar depression. The references of literature found were cross-referenced. The pharmaceutical company that produces quetiapine was contacted to obtain the posters for the EMBOLDEN I and EMBOLDEN II trials. STUDY SELECTION AND DATA EXTRACTION: Only double-blind, placebo-controlled trials were included for review, as well as any subanalyses of the literature that matched this criterion. DATA SYNTHESIS: There was a total of 5 double-blind, placebo-controlled trials and 5 subanalyses reviewed. The results of these data demonstrated quetiapine's efficacy in the treatment of depressive phases of bipolar disorder, including statistically significant improvement in the Montgomery-Asberg Depression Rating Scale (MADRS). In the trials reviewed in this article, the change in MADRS scores ranged from -15.4 to -16.94 within the quetiapine groups, and from -10.26 to -11.93 in the placebo groups. There were also statistically significant improvements in the Hamilton Anxiety Rating Scale, the Short Form of the Quality of Life Enjoyment and Satisfaction Questionnaire, the Pittsburgh Sleep Quality Index, and the Sheehan Disability Scale. All of these trials had a duration of 8 weeks and therefore cannot be applied to the long-term use of quetiapine in bipolar depression. The most common adverse events were sedation, somnolence, and dry mouth. The overall dropout rates for the trials reviewed ranged from 24% to 47%. CONCLUSIONS: Based on the literature reviewed here, quetiapine appears to be a safe and efficacious short-term treatment option for bipolar depression. Patients with bipolar type I showed greater improvement on the MADRS than those with bipolar type II. Patients with a rapid-cycling disease course showed an improvement in depressive symptoms, regardless of bipolar type.

Steady-state pharmacokinetic, safety, and tolerability profiles of quetiapine, norquetiapine, and other quetiapine metabolites in pediatric and adult patients with psychotic disorders.

OBJECTIVE: The aim of this study was to investigate the steady-state pharmacokinetic, safety, and tolerability profiles of immediate-release quetiapine administered by similar dose-escalation regimens in pediatric and adult populations with psychotic or mood disorders. METHODS: Pediatric patients aged 10-17 years were titrated to a quetiapine dose of 200 mg twice daily (b.i.d. on days 5-7, 400 mg b.i.d. on days 11-12, with a final 400-mg dose on day 13. In a separate trial, adult patients aged 18-45 years were titrated to a quetiapine dose of 200 mg b.i.d. on days 4-6, 400 mg b.i.d. on days 10-11, with a final 400-mg dose on day 12. Concentrations of quetiapine and three metabolites (quetiapine sulfoxide, 7-hydroxy quetiapine, and norquetiapine) were quantified in plasma and urine. Adverse events, vital signs, 12-lead electrocardiogram (ECG), and clinical laboratory tests were evaluated throughout the studies. RESULTS: In both pediatric and adult populations, plasma concentrations of quetiapine and norquetiapine increased proportionately as the dose was escalated from 200 mg b.i.d. to 400 mg b.i.d. There were no age-related differences in the dose-normalized quetiapine plasma concentration-time curve (AUC(SS)) and maximum plasma concentration (C(SS,max)). Quetiapine was rapidly absorbed after 200-mg and 400-mg doses in pediatric patients [median t(max) (time to maximum plasma concentration) 1.5 hours, both doses] and adult patients (median t(max) 1.0 hour and 1.2 hours, respectively). The mean quetiapine t(1/2) (terminal elimination half-life) was approximately 6 hours for pediatric and 5 hours for adult patients. Norquetiapine displayed a similar median t(max) and a longer t(1/2) compared with quetiapine. Quetiapine was well tolerated, with no serious adverse events and no unexpected events reported. CONCLUSION: Pediatric and adult populations demonstrated similar pharmacokinetic, safety, and tolerability profiles for quetiapine administered by dose escalation. The predictability in quetiapine concentration profiles for children aged 10 years to adults suggests that no dosage adjustment may be required when treating patients of these ages.