Safety and tolerability of once-daily extended release quetiapine fumarate in acute schizophrenia: pooled data from randomised, double-blind, placebo-controlled studies

Efficacy of quetiapine XR vs. placebo as concomitant treatment to mood stabilizers in the control of subthreshold symptoms of bipolar disorder: Results from a pilot, randomized controlled trial

Patients with bipolar disorder (BD) do not always achieve full remission between episodes. Subthreshold symptoms (depressive, manic or mixed) represent a major cause of relapse and disability in these patients. Immediate release (IR) and extended release (XR) formulations of quetiapine are both indicated for short and long-term treatment of BD. The aim of this study was to evaluate the efficacy of quetiapine XR vs placebo in subthreshold symptomatology when added to previous mood stabilizer treatment. A pilot phase IIIB, multicentre, prospective, placebo controlled, randomized, double blinded study of 12 weeks follow-up was performed (NCT01197846). Patients were randomized to quetiapine XR 300mg or placebo once daily. The primary outcome was the mean change between quetiapine XR and placebo from baseline to study endpoint (week 6) in the Montgomery-Åsberg Depression Rating Scale (MADRS). Quetiapine XR 300mg (n=16) significantly improved depressive subthreshold symptoms compared with placebo (n=16) after 6 weeks (P=0.021). Early response (reduction of at least the 20% of the MADRS total score) and remission rate (reduction in MADRS total score <8 and YMRS<8) did not show differences between groups. Quetiapine XR did not show superiority vs placebo when evaluating subthreshold manic symptoms, instead it was superior when evaluating functioning (GAF score) in BD type I patients (P=0.005). The most common adverse events were somnolence (9.1%), increased appetite, dry mouth and dizziness (6.8%). Quetiapine XR 300mg once daily was significantly more effective than placebo in depressive subthreshold symptoms. Adverse events were consistent with the known side effects of quetiapine.

Evaluation of the use of low-dose quetiapine and the risk of metabolic consequences: A retrospective review

Introduction

Quetiapine fumarate is an atypical antipsychotic approved for the treatment of schizophrenia, major depressive disorder, and bipolar disorder. Due to the sedative effects observed at low doses, prescribers use quetiapine to aid patients with sleep disturbances. Current evidence has established that quetiapine can cause negative changes in metabolic parameters, but it is unknown if these consequences also occur at low doses. Due to the use of quetiapine for sleep, the purpose of this study is to identify if metabolic effects are also a risk with the use of low-dose quetiapine.

Methods

Eligible subjects were identified through the Veterans Affairs electronic medical records as having an active prescription for quetiapine from June 30, 2012, through September 1, 2013. Subjects were then evaluated using inclusion and exclusion criteria for determination of study entrance. Descriptive statistics and t tests were utilized to identify clinical and statistical differences in outcomes.

Results

A total of 403 subjects were included in the final analysis. The average dose of quetiapine was 116.8 mg and average duration of therapy was 44 months. Increases were observed in systolic blood pressure (+1.95 mmHg; P = .036), diastolic blood pressure (+1.97 mmHg; P = .001), body mass index (+0.52; P = .001), weight (+1.88 kg; P = .002), and fasting blood glucose (+6.71 mg/dL; P = .002). Conversely, a decrease in total cholesterol (-10.06 mg/dL; P < .001) was recognized.

Discussion

As a result of the findings, there may be negative metabolic consequences with the use of low-dose quetiapine. Routine prescribing of low doses for sleep as a first-line medication should be avoided.

Efficacy and safety of quetiapine extended release monotherapy in bipolar depression: a multi-center, randomized, double-blind, placebo-controlled trial

RATIONALE

Quetiapine extended release (XR) has been used to treat various psychiatric disorders, including depressive episodes associated with bipolar I and II disorders. Quetiapine XR is the first approved drug in China for the treatment of bipolar disorder.

OBJECTIVES

The study evaluated the efficacy and safety of short-term quetiapine XR monotherapy in the treatment of depressive episodes of bipolar I and II disorders.

METHODS

This was an 8-week multi-center, randomized, double-blind, placebo-controlled, fixed-dose phase 3 study. The primary endpoint was the mean change of the Montgomery-Åsberg Depression Rating Scale (MADRS) total score. Secondary endpoints included Clinical Global Impressions-Bipolar (CGI-BP) and remission rates.

RESULTS

The study recruited 279 adult bipolar I or II patients currently experiencing depression from 11 Chinese provinces. Of these, 139 received quetiapine XR (300 mg/day) and 140 received placebo for 8 weeks. The mean change in the MADRS total score was significantly greater in the quetiapine XR group than in the placebo group (-19.00 ± 7.88 vs. -16.20 ± 9.32; p = 0.004). Adverse events occurred in 96 patients (65.3 %) in the quetiapine XR group and 72 (49.0 %) in the placebo group. The incidence of serious adverse events did not differ significantly between the groups (p = 0.247).

CONCLUSIONS

This study, which is the first to evaluate 300 mg/day quetiapine XR monotherapy for depression in Chinese patients with bipolar disorders, found that this drug was superior to the placebo. Quetiapine XR was generally safe and well tolerated (ClinicalTrials.gov number, NCT01256177).

Comparison of the effects of quetiapine extended-release and quetiapine immediate-release on cognitive performance, sedation and patient satisfaction in patients with schizophrenia: a randomised, double-blind, crossover study (eXtRa)

OBJECTIVES

To assess daytime cognitive performance, sedation and treatment satisfaction in patients with schizophrenia receiving quetiapine extended release (XR) versus quetiapine immediate release (IR).

METHODS

Phase IV prospective, double-blind, crossover study (NCT01213836). Patients (N=66) with stable schizophrenia, treated with XR or IR before study start, were randomised (1:1) to treatment with XR followed by IR, or IR followed by XR, at the dose received before enrolment (400-750mg). After 10-16days on formulation 1, patients switched to formulation 2. Assessments from three post-dose visits (≥5days following treatment on each formulation) were analysed. Cognitive performance was measured by CogState Cognition testing. Sedation, treatment satisfaction and safety were also assessed.

RESULTS

65 patients received treatment (69.2% male; mean age 37.8years). Daytime cognitive functioning was similar for both groups; adjusted mean difference in Attentional Composite Score in XR and IR patients was 0.005 (p=0.907). Patients receiving XR were less sedated than those receiving IR, (Bond-Lader visual analogue scale score, mean [SD]: 23.5 [19.0] vs 28.6 [21.4]); estimated overall treatment difference: 5.2 (95% CI: 2.3, 8.2; p<0.0009). Patients receiving XR reported feeling less sedated than those on IR (Stanford Sleepiness Scale, mean [SD]: 2.4 [0.9] vs 2.6 [1.0]); estimated overall treatment difference: 0.28 (95% CI: 0.12, 0.43; p<0.0008). Patients reported improved overall treatment satisfaction (p=0.0417) and milder side effects (p=0.0035) with XR. Safety profile was similar in both groups.

CONCLUSION

Daytime cognitive performance was similar for both groups. XR was associated with less daytime sedation and improved patient satisfaction than IR.

The efficacy and safety of once-daily quetiapine extended release in patients with schizophrenia switched from other antipsychotics: an open-label study in Chinese population

BACKGROUND

Non-adherence to antipsychotic medication in schizophrenic patients is common and associated with symptom relapse and poorer long-term outcomes. The risk factors for treatment non-adherence include dosing frequency and complexity. Besides, slower dose titration in an acute schizophrenic episode may lead to attenuated efficacy. Therefore, the convenient dosage regimen and rapid initiation scheme of quetiapine extended release (XR) were expected to provide better effectiveness and promote adherence in patients with schizophrenia. This study was implemented to assess the efficacy and safety of once-daily quetiapine XR in schizophrenic patients with switched from other antipsychotics which were suboptimal due to insufficient efficacy or tolerability.

METHODS

This was a 12-week, open-label study conducted in the Chinese population in Taiwan. Patients who had a score of 4 (moderate) or greater on any of the 7 items of the Positive and Negative Syndrome Scale (PANSS) Positive Symptom Subscale and needed to switch from previous antipsychotics were recruited. Quetiapine XR was administered at 300 mg on day 1, 600 mg on day 2 and up to 800 mg after day 2. From day 8 until the end of the study, the dose of quetiapine XR was adjusted within 400-800 mg per day, depending on the clinical response and tolerance of the patients. The variable of the primary outcome was the change from baseline to Week 12 in PANSS total and subscale scores. Secondary outcome was the baseline-to-endpoint difference in the Clinical Global Impression-Severity (CGI-S) scores of the participants.

RESULTS

Sixty-one patients were recruited and 55.7% of them completed the study. The mean changes in the PANSS total score and CGI-S score showed significant improvement (-18.4, p < .001 and -1.0, p < .001, respectively). Four patients (6.7%) experienced adverse events including headache, exacerbation of psychosis and dysuria. The use of concomitant anticholinergics decreased from 15.0% to 8.3%.

CONCLUSIONS

The results of our investigation implicated that quetiapine XR was an effective and well tolerated alternative for Chinese schizophrenic patients with previous suboptimal treatment. Future large-scale studies are warranted to validate our results.

TRIAL REGISTRATION

ClinicalTrials.gov ID NCT02142556 . Registered 15 May 2014.

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

OBJECTIVES

A series of studies were conducted to guide the development and characterise the pharmacokinetics of extended-release quetiapine fumarate (quetiapine XR), a once-daily formulation to control the release of the drug.

METHODS

Data from these studies are described and discussed herein.

RESULTS

Once-daily quetiapine XR produced a similar area under the plasma concentration-time curve (AUC), minimum plasma concentration (Cmin) and a slightly lower maximum plasma concentration (Cmax) than the equivalent dose of immediate-release quetiapine (quetiapine IR) given twice daily. In a crossover, head-to-head study, total daily exposure, measured by AUC at steady state, was less variable with quetiapine XR versus quetiapine IR (percent coefficient of variation 39.2% versus 51.2%, respectively). Compared with fasting, a high-fat meal increased the AUC and Cmax for quetiapine XR, whereas a light meal had no significant effect on these parameters. Quetiapine XR exhibits a less pronounced D2 receptor occupancy peak and receptor occupancy levels remain higher for longer compared with quetiapine IR. Quetiapine XR was generally well tolerated with a safety profile similar to quetiapine IR, although the intensity of sedation in the first hours of treatment was significantly lower (p < 0.01) with quetiapine XR versus IR.

CONCLUSION

At steady state, quetiapine XR provided a similar AUC and Cmin and a slightly lower Cmax relative to an equivalent dose of quetiapine IR administered twice daily. Quetiapine XR exhibited linear pharmacokinetics in the dose range tested and no food effect was observed with a light meal. Once-daily dosing and simpler dose titration makes using quetiapine XR convenient for clinicians and patients. Quetiapine XR has predictable pharmacokinetics and was generally well tolerated, with significantly lower intensity of sedation after the first hours of administration compared with quetiapine IR. With once-daily quetiapine XR, the impact of daytime sedation may be mitigated by evening dosing.

Efficacy and safety of lurasidone 80 mg/day and 160 mg/day in the treatment of schizophrenia: a randomized, double-blind, placebo- and active-controlled trial

OBJECTIVE

This study was designed to evaluate the short-term efficacy and safety of once-daily lurasidone (80 mg/day and 160 mg/day) in the treatment of an acute exacerbation of schizophrenia.

METHODS

Participants, who were recently admitted inpatients with schizophrenia with an acute exacerbation of psychotic symptoms, were randomly assigned to 6 weeks of fixed-dose, double-blind treatment with lurasidone 80 mg (n=125), lurasidone 160 mg (n=121), quetiapine XR 600 mg (QXR-600 mg; n=119; active control included to test for assay sensitivity), or placebo (n=121), all dosed once daily in the evening. Efficacy was evaluated using a mixed-model repeated-measures analysis of the change from Baseline to Week 6 in Positive and Negative Syndrome Scale (PANSS) total score (the primary efficacy measure) and Clinical Global Impressions severity (CGI-S) score (the key secondary efficacy measure).

RESULTS

Treatment with both doses of lurasidone or with QXR-600 mg was associated with significantly greater improvement at Week 6 on PANSS total score, PANSS positive and negative subscale scores, and CGI-S score compared with placebo. The endpoint responder rate (≥ 20% improvement in PANSS total score) was higher in subjects treated with lurasidone 80 mg (65%; p<0.001), lurasidone 160 mg (79%; p<0.001), and QXR-600 mg (79%; p<0.001) compared with placebo (41%). The proportion of patients experiencing ≥ 7% weight gain was 4% for each lurasidone group, 15% for the QXR-600 mg group, and 3% for the placebo group. Endpoint changes in levels of cholesterol, triglycerides, and low-density lipoprotein (LDL) cholesterol were comparable for both lurasidone groups and placebo, while the QXR-600 mg group showed a significant median increase compared with the placebo group in levels of cholesterol (p<0.001), LDL cholesterol (p<0.01), and triglycerides (p<0.05).

CONCLUSIONS

Lurasidone 80 mg and 160 mg doses administered once-daily in the evening, were safe and effective treatments for subjects with acute schizophrenia, with increased response rates observed at the higher dose. Dose-related adverse effects were limited, and both doses were generally well-tolerated.

The long-term clinical benefit and effectiveness of switching to once-daily quetiapine extended release in patients with schizophrenia

OBJECTIVE

To evaluate the long-term clinical benefit and effectiveness of switching to once-daily quetiapine extended release (XR) from an oral antipsychotic in patients with schizophrenia. Reasons for switching included insufficient efficacy, tolerability, and/or non-acceptability. The primary endpoint was the percentage of patients achieving an improvement in Clinical Global Impression - Clinical Benefit (CGI-CB) scale scores.

RESEARCH DESIGN AND METHODS

A 24-week, international, multicentre, open-label, prospective study ( www.clinicaltrials.gov : NCT00640601). After a 7-14 day enrolment period (depending whether prior antipsychotic mono- or combination therapy), all patients received quetiapine XR 300 mg once daily (day 1), 600 mg/day (day 2), 600-800 mg/day (day 3) and 400-800 mg/day thereafter, with down-titration and discontinuation of prior antipsychotic by day 4.

RESULTS

A total of 62% of patients completed the study and 56.9% (LOCF, ITT) achieved a significant improvement in CGI-CB (95% CI [0.51, 0.63]; p = 0.02). Switches due to insufficient efficacy showed a significant improvement (60%, 95% CI [0.51, 0.68]; p = 0.02), compared to 54.4% ([0.44, 0.64]; p = 0.38) and 52.4% ([0.36, 0.68]; p = 0.76) of switches due to insufficient tolerability and non-acceptability respectively (both p = ns). Patients previously on olanzapine and quetiapine IR showed a significant improvement in CGI-CB (62.6% [p = 0.02] and 61.2% [p = 0.04], respectively). Somnolence (18.0%) and dizziness (14.6%) were the main adverse events. Anticholinergic use decreased from 7.1 to 2.7%. Overall mean weight gain was 0.4 kg; 12.9% of patients experienced a weight gain of ≥7% and 15% experienced a clinically relevant shift in triglycerides from baseline.

CONCLUSIONS

A majority of patients switched from other antipsychotics to quetiapine XR experienced clinical benefit. This was supported by all other efficacy outcomes regardless of the reason for switching. Safety data confirmed quetiapine XR was safe and well tolerated. The open-label design and lack of a placebo group represent limitations.

Use of quetiapine XR and quetiapine IR in clinical practice for hospitalized patients with schizophrenia: a retrospective study

Quetiapine fumarate, a first-line treatment for schizophrenia, exists in two formulations: extended release (XR) and immediate release (IR). This naturalistic, noninterventional study evaluated use of quetiapine XR/IR among in-patients with schizophrenia [ClinicalTrials.gov identifier: NCT01214135]. Data were collected from medical records. Categorical and numerical outcomes were compared using χ(2) and t tests. Of 178 enrolled patients, 66% and 34% used quetiapine XR and IR respectively. Based on mean daily dose, XR was used as antipsychotic medication in 64% of patients compared with 40% of patients on IR (dose ≥ 400 mg/day; p = 0.002) and in higher doses than IR (494 versus 345 mg/day; p = 0.001; calculated averages). Schizophrenia was more commonly reported as reason for use of XR than IR (20% versus 0%; p = 0.0003). Patients with comorbid substance abuse or somatic disease were more likely to receive XR (p = 0.003; p = 0.03). Treatment cessation due to nonadherence was less common in patients on XR (3.4% versus 12%; p = 0.03). Polypharmacy was seen in 98% of patients. Quetiapine XR/IR usage varies in hospitalized patients with schizophrenia. XR is more often used in antipsychotic dosage; IR is more commonly used at lower doses as add-on therapy. Both quetiapine XR and IR have their place in clinical practice and provide treatment choice in schizophrenia.

A retrospective study of clinical usage of quetiapine XR and quetiapine IR in outpatients with schizophrenia in Denmark

OBJECTIVES

The atypical antipsychotic quetiapine is a first-line treatment for schizophrenia. This non-interventional study (NCT01212575) evaluated the clinical use of its two formulations, extended release (XR) and immediate release (IR), in outpatients with schizophrenia spectrum disorder.

METHODS

Patients who had received at least one dose of quetiapine XR and/or IR were included. A dosage ≥400 mg/day was defined as antipsychotic. Medical records data were collected retrospectively.

RESULTS

Of 186 enrolled patients, 99 (53%) and 87 (47%) received quetiapine XR and IR, respectively. Use in antipsychotic dosage was seen for 89% XR versus 63% IR patients (mean daily dose ≥400 mg/day; p < 0.0001). 75% XR and 53% IR patients used dosages ≥600 mg/day (p = 0.0019). Quetiapine XR was used at higher mean daily dosages than IR (748 vs 566 mg/day; p = 0.006). Forty-three patients (23%) used both formulations concomitantly; 55 patients (30%) used either XR or IR. Quetiapine IR was used as-needed in 44 patients (23%); one patient used XR as-needed.

CONCLUSIONS

Quetiapine XR was used more often in higher (antipsychotic) dosages; quetiapine IR more frequently on an as-needed administration basis. Concomitant use was seen. These findings probably reflect the different profiles of XR/IR and advocate the need for both formulations to offer treatment choice.

Flexible dosing with paliperidone ER in the treatment of patients with acutely exacerbated schizophrenia: results from a single-arm, open-label study

OBJECTIVE

To extend findings from fixed-dose, double-blind, placebo-controlled clinical trials in selected patient populations by using flexibly-dosed oral paliperidone extended-release (ER) in a more naturalistic setting.

METHODS

Adults hospitalized with an acute exacerbation of schizophrenia were prospectively treated with open-label flexibly-dosed paliperidone ER 3-12 mg/day for 6 weeks.

RESULTS

Overall, 294 patients were treated. The primary endpoint, defined as ≥30% improvement in Positive and Negative Syndrome Scale total scores from baseline to endpoint, was achieved by 66.3% of patients. The percentage of patients rated as at least 'markedly ill' in Clinical Global Impression of Severity scale decreased from baseline (74.1%) to endpoint (20.0%). Patient functioning, assessed by the Personal and Social Performance scale, improved significantly from 50.0 ± 14.3 at baseline to 63.6 ± 14.9 at endpoint (p < 0.0001). Concomitant benzodiazepines were newly initiated in 191 patients (65.0%), and new concomitant medications other than benzodiazepines were started after baseline for 133 patients (45.2%), most frequently paracetamol, zolpidem, and zopiclone. No unexpected adverse events were identified.

CONCLUSIONS

These data support findings in more selected patient populations treated with fixed-dose paliperidone ER. Flexibly-dosed paliperidone ER administered in a naturalistic hospital setting to a more representative patient population experiencing an acute episode of schizophrenia, was associated with clinically meaningful treatment response. Strength of conclusions is limited by the open-label design and lack of a comparator group. Furthermore, some of the improvements observed may in part be associated with increased attention provided to patients and concomitant use of psychotropic medications, such as benzodiazepines, during this study.

Differential use of extended and immediate release quetiapine: a retrospective registry study of Finnish inpatients with schizophrenia spectrum and bipolar disorders

OBJECTIVE

Extended release (XR) and immediate release (IR) quetiapine have differing dosing, titration and plasma concentration profiles. The authors assessed whether the use of quetiapine XR and IR in schizophrenia spectrum disorders (SCZ) and bipolar disorder (BD) differ.

DESIGN

Retrospective non-interventional registry study.

SETTING

Secondary healthcare.

PARTICIPANTS

All SCZ and BD (ICD-10 codes F20-F29, F30-F31) patients discharged between June 2008 and June 2010 from a Finnish psychiatric hospital with any use of quetiapine during their inpatient stay.

PRIMARY AND SECONDARY OUTCOME MEASURES

Differences in patient characteristics between quetiapine XR and IR users were tested. To assess the profile of XR versus IR patients, logistic regressions were performed.

RESULTS

43 patients used quetiapine XR, 58 used quetiapine IR and 55 used both formulations (n=156). 102 patients were diagnosed with SCZ and 54 with BD, with no significant differences between the quetiapine formulations. The mean daily dose of quetiapine XR was significantly higher than that of quetiapine IR (542 mg vs 328 mg; p<0.001). This was also true for the SCZ subgroup (XR: 593 mg vs IR: 338 mg; p<0.001) and the BD subgroup (XR: 466 mg vs IR: 308 mg; p=0.009). 48% of all quetiapine IR patients used a mean dose of ≤200 mg compared with 2% of XR patients. Injectable antipsychotics were combined with quetiapine IR but not with quetiapine XR (12% vs 0%; p=0.019). At discharge, quetiapine XR was used as monotherapy to a greater extent than IR (79% vs 44%; p=0.003). The odds for quetiapine XR use in hospital were lower with advancing age, substance abuse diagnosis and prior IR use.

CONCLUSIONS

Among SCZ and BD inpatients, quetiapine XR was more often used as monotherapy and in significantly higher doses than quetiapine IR. Differential use of the quetiapine formulations appears to depend, at least in part, on patient characteristics.

Safety of quetiapine fumarate extended release in the treatment of Korean patients with acute schizophrenia

INTRODUCTION

The aim of this study was to evaluate the efficacy and safety of quetiapine fumarate extended release (XR) in the treatment of Korean subjects with acute schizophrenia.

METHODS

This was an 8-week, multi-center, open-label, non-comparative study to evaluate the efficacy and safety of quetiapine fumarate XR at a daily dose of 400-800 mg. Changes in total scores on the Positive and Negative Syndrome Scale (PANSS) from baseline to week 8 were analyzed to evaluate the efficacy of quetiapine XR. Additionally, the Clinical Global Impression scale and the Montgomery-Åsberg Depression Rating Scale were administered.

RESULTS

The mean change in PANSS total scores was -26.8, and the mean PANSS total score at the endpoint was significantly lower than that at baseline. The mean PANSS positive score, negative score, and general score showed statistically significant reductions at the end of the study. Statistically significant changes were also observed in Clinical Global Impression-Severity and Montgomery-Åsberg Depression Rating Scale scores. The most common treatment-related adverse events in the group receiving quetiapine XR were sedation (10.6%) and constipation (9.6%).

CONCLUSIONS

In this study of Korean patients with acute schizophrenia, quetiapine XR showed clinical efficacy and relatively good tolerability.

Update on extended release quetiapine fumarate in schizophrenia and bipolar disorders

The atypical antipsychotic quetiapine fumarate is available both as an immediate release (IR) and as an extended release (XR) formulation allowing flexibility of dosing for individual patients. Approved uses of quetiapine XR include the treatment of schizophrenia (including maintenance therapy for prevention of relapse), the treatment of bipolar disorder (manic and depressive episodes), and the prevention of recurrence in patients with bipolar disorder who respond to quetiapine XR. This narrative review provides an update on quetiapine XR in these indications. The pharmacological profile of quetiapine, including a moderate affinity for dopamine D(2) receptors and higher affinity for serotonin 5-hydroxytryptophan (5-HT)(2A) receptors, may explain its broad efficacy and low propensity for extrapyramidal symptoms (EPS). The XR formulation has similar bioavailability but prolonged plasma levels compared with the IR formulation, allowing for less frequent (once-daily) dosing. Clinical studies have confirmed the efficacy of quetiapine XR in relieving the acute symptoms of schizophrenia during short-term trials, and reducing the risk for relapse in long-term studies. Direct switching from the IR formulation to the same dose of the XR formulation did not reveal any loss of efficacy or tolerability issues, and switching patients to quetiapine XR from conventional or other atypical antipsychotics (for reasons of insufficient efficacy or tolerability) also proved to be beneficial and generally well tolerated. In bipolar disorder, quetiapine XR has also proven effective in relieving acute depressive and manic symptoms. Adverse events with quetiapine XR in patients with either schizophrenia or bipolar disorder are similar to those associated with the IR formulation, the most common being sedation, dry mouth, somnolence, dizziness, and headache. The low propensity for EPS is maintained with the XR formulation. Overall, evidence from clinical trials suggests that quetiapine XR is an effective and generally well-tolerated treatment option in patients with schizophrenia and bipolar disorder.

The management of schizophrenia: focus on extended-release quetiapine fumarate

Effective management of schizophrenia remains a significant clinical challenge. While antipsychotic medications have proven efficacy in this disease, there remains an opportunity to further improve symptom control and long-term relapse prevention. Also, a number of factors, including tolerability and complex dosing regimens, can result in nonadherence to medication. Quetiapine is an atypical antipsychotic with proven efficacy and an established tolerability profile in schizophrenia. The once-daily extended-release formulation (quetiapine XR) offers a simplified dosing regimen and titration schedule. Short-term clinical studies have shown that quetiapine XR (400-800 mg/d) is efficacious in the acute treatment of schizophrenia, while a long-term study has shown that quetiapine XR was significantly more effective than placebo at preventing relapse. Furthermore, an investigation in which stable patients switched from the immediate-release formulation (quetiapine IR) to quetiapine XR showed that quetiapine XR is generally well tolerated and has no loss of efficacy compared with quetiapine IR. In patients who experienced insufficient efficacy or poor tolerability on their previous antipsychotic, switching to quetiapine XR significantly improved efficacy compared with the previous treatment. In conclusion, quetiapine XR is an effective and generally well tolerated treatment for schizophrenia. Furthermore, once-daily dosing may improve patient adherence, which may impact positively on patient outcomes.