|Pharmacotherapeutic group: AntipsychoticsATC code: N05A H04|
Mechanism of action:Quetiapine is an atypical antipsychotic agent. Quetiapine and the active human plasma metabolite, norquetiapine interact with a broad range of neurotransmitter receptors. Quetiapine and norquetiapine exhibit affinity for brain serotonin (5HT2) and dopamine D1- and D2-receptors. It is this combination of receptor antagonism with a higher selectivity for 5HT2 relative to D2-receptors, which is believed to contribute to the clinical antipsychotic properties and low extrapyramidal side effect (EPS) liability of Seroquel compared to typical antipsychotics. Additionally, norquetiapine has high affinity for the norepinephrine transporter (NET). Quetiapine and norquetiapine also have high affinity at histaminergic and adrenergic α1-receptors, with a lower affinity at adrenergic α2 and serotonin 5HT1A receptors. Quetiapine has no appreciable affinity at muscarinic or benzodiazepine receptors.
Pharmacodynamic effects:Quetiapine is active in tests for antipsychotic activity, such as conditioned avoidance. It also blocks the action of dopamine agonists, measured either behaviourally or electrophysiologically, and elevates dopamine metabolite concentrations, a neurochemical index of D2-receptor blockade. The extent to which the norquetiapine metabolite contributes to the pharmacological activity of Seroquel in humans is not known.In pre-clinical tests predictive of EPS, quetiapine is unlike typical antipsychotics and has an atypical profile. Quetiapine does not produce dopamine D2-receptor supersensitivity after chronic administration. Quetiapine produces only weak catalepsy at effective dopamine D2-receptor blocking doses. Quetiapine demonstrates selectivity for the limbic system by producing depolarisation blockade of the mesolimbic but not the nigrostriatal dopamine-containing neurones following chronic administration. Quetiapine exhibits minimal dystonic liability in haloperidol-sensitised or drug-naive Cebus monkeys after acute and chronic administration. (See Section 4.8 Undesirable effects)
SchizophreniaThe efficacy of Seroquel XL in the treatment of schizophrenia was demonstrated in one 6-week placebo-controlled trial in patients who met DSM-IV criteria for schizophrenia, and one active-controlled Seroquel IR-to-Seroquel XL switching study in clinically stable outpatients with schizophrenia.The primary outcome variable in the placebo-controlled trial was change from baseline to final assessment in the PANSS total score. Seroquel XL 400 mg/day, 600 mg/day and 800 mg/day were associated with statistically significant improvements in psychotic symptoms compared to placebo. The effect size of the 600 mg and 800 mg doses was greater than that of the 400 mg dose.In the 6-week active-controlled switching study the primary outcome variable was the proportion of patients who showed lack of efficacy, i.e., who discontinued study treatment due to lack of efficacy or whose PANSS total score increased 20% or more from randomisation to any visit. In patients stabilised on Seroquel IR 400 mg to 800 mg, efficacy was maintained when patients were switched to an equivalent daily dose of Seroquel XL given once daily.In a long-term study in stable schizophrenic patients who had been maintained on Seroquel XL for 16 weeks, Seroquel XL was more effective than placebo in preventing relapse. The estimated risks of relapse after 6 months treatments was 14.3% for the Seroquel XL treatment group compared to 68.2% for placebo. The average dose was 669 mg. There were no additional safety findings associated with treatment with Seroquel XL for up to 9 months (median 7 months). In particular, reports of adverse events related to EPS and weight gain did not increase with longer-term treatment with Seroquel XL.
Bipolar DisorderIn the treatment of moderate to severe manic episodes, quetiapine demonstrated superior efficacy to placebo in reduction of manic symptoms at 3 and 12 weeks, in two monotherapy trials. There are no data from long-term studies to demonstrate quetiapine's effectiveness in preventing subsequent manic or depressive episodes. Quetiapine data in combination with divalproex or lithium in moderate to severe manic episodes at 3 and 6 weeks is limited; however, combination therapy was well tolerated. The data showed an additive effect at week 3. A second study did not demonstrate an additive effect at week 6. There are no combination data available beyond week 6. The mean last week median dose of quetiapine in responders was approximately 600 mg/day and approximately 85% of the responders were in the dose range of 400 to 800 mg/day. In a clinical trial, in patients with depressive episodes in bipolar I or bipolar II disorder, 300 mg/day Seroquel XL showed superior efficacy to placebo in reduction of MADRS total score. The antidepressant effect of Seroquel XL was significant at Day 8 (week 1) and was maintained through the end of the trial (week 8). In 4 additional clinical trials in patients with depressive episodes in bipolar I or bipolar II disorder, with and without rapid cycling courses, 51% of quetiapine treated patients had at least a 50% improvement in MADRS total score at week 8 compared to 37% of the placebo treated patients. The anti-depressant effect was significant at Day 8 (week 1). There were fewer episodes of treatment-emergent mania with Seroquel than with placebo. In continuation treatment the anti-depressant effect was maintained for patients on Seroquel (mean duration of treatment 30 weeks). Seroquel reduced the risk of a recurrent mood (manic and depressed) event by 49%. Seroquel was superior to placebo in treating the anxiety symptoms associated with bipolar depression as assessed by mean change from baseline to week 8 in HAM-A total score.In one long-term study (up to 2 years treatment, mean quetiapine exposure 191 days) evaluating recurrence prevention in patients with manic, depressed or mixed mood episodes quetiapine was superior to placebo in increasing the time to recurrence of any mood event (manic, mixed or depressed), in patients with bipolar I disorder. The number of patients with a mood event was 91 (22.5%) in the quetiapine group, 208 (51.5%) in the placebo group and 95 (26.1%) in the lithium treatment groups respectively. In patients who responded to quetiapine, when comparing continued treatment with quetiapine to switching to lithium, the results indicated that a switch to lithium treatment does not appear to be associated with an increased time to recurrence of a mood event.In two recurrence prevention studies evaluating quetiapine in combination with mood stabilizers, in patients with manic, depressed or mixed mood episodes, the combination with quetiapine was superior to mood stabilizers monotherapy in increasing the time to recurrence of any mood event (manic, mixed or depressed). The risk of a recurrent event was reduced by 70%. Quetiapine was administered twice-daily totalling 400 mg to 800 mg a day as combination therapy to lithium or valproate.
Major depressive episodes in MDDTwo short-term (6 week) studies enrolled patients who had shown an inadequate response to at least one antidepressant. Seroquel XL 150 mg and 300 mg/day, given as add-on treatment to ongoing antidepressant therapy (amitriptyline, bupropion, citalopram, duloxetine, escitalopram, fluoxetine, paroxetine, sertraline or venlafaxine) demonstrated superiority over antidepressant therapy alone in reducing depressive symptoms as measured by improvement in MADRS total score (LS mean change vs. placebo of 2-3.3 points). Long-term efficacy and safety in patients with MDD has not been evaluated as add-on therapy, however long-term efficacy and safety has been evaluated in adult patients as monotherapy (see below). The following studies were conducted with Seroquel XL as monotherapy treatment, however Seroquel XL is only indicated for use as add-on therapy:In three out of four short term (up to 8 weeks) monotherapy studies, in patients with major depressive disorder, Seroquel XL 50 mg, 150 mg and 300 mg/day demonstrated superior efficacy to placebo in reducing depressive symptoms as measured by improvement in the Montgomery-Åsberg Depression Rating Scale (MADRS) total score (LS mean change vs. placebo of 2-4 points). In a monotherapy relapse prevention study, patients with depressive episodes stabilised on open-label Seroquel XL treatment for at least 12 weeks were randomised to either Seroquel XL once daily or placebo for up to 52 weeks. The mean dose of Seroquel XL during the randomised phase was 177 mg/day. The incidence of relapse was 14.2% for Seroquel XL treated patients and 34.4% for placebo-treated patients.In a short-term (9 week) study non-demented elderly patients (aged 66 to 89 years) with major depressive disorder, Seroquel XL dosed flexibly in the range of 50 mg to 300 mg/day demonstrated superior efficacy to placebo in reducing depressive symptoms as measured by improvement in MADRS total score (LS mean change vs placebo -7.54). In this study patients randomised to Seroquel XL received 50 mg/day on Days 1-3, the dose could be increased to 100 mg/day on Day 4, 150 mg/day on Day 8 and up to 300 mg/day depending on clinical response and tolerability. The mean dose of Seroquel XL was 160 mg/day. Other than the incidence of extrapyramidal symptoms (see section 4.8 Undesirable effects and 'Clinical Safety' below) the tolerability of Seroquel XL once daily in elderly patients was comparable to that seen in adults (aged 18-65 years). The proportion of randomised patients over 75 years of age was 19%.
Clinical safety:In short-term, placebo-controlled clinical trials in schizophrenia and bipolar mania the aggregated incidence of extrapyramidal symptoms was similar to placebo (schizophrenia: 7.8% for quetiapine and 8.0% for placebo; bipolar mania: 11.2% for quetiapine and 11.4% for placebo). Higher rates of extrapyramidal symptoms were seen in quetiapine treated patients compared to those treated with placebo in short-term, placebo-controlled clinical trials in MDD and bipolar depression. In short-term, placebo-controlled bipolar depression trials the aggregated incidence of extrapyramidal symptoms was 8.9% for quetiapine compared to 3.8% for placebo. In short-term, placebo-controlled monotherapy clinical trials in major depressive disorder the aggregated incidence of extrapyramidal symptoms was 5.4% for Seroquel XL and 3.2% for placebo. In a short-term placebo-controlled monotherapy trial in elderly patients with major depressive disorder, the aggregated incidence of extrapyramidal symptoms was 9.0% for Seroquel XL and 2.3% for placebo. In both bipolar depression and MDD, the incidence of the individual adverse events was generally low and did not exceed 4% in any treatment group. In short term, fixed dose (50 mg/d to 800 mg/d), placebo-controlled studies (ranging from 3 to 8 weeks), the mean weight gain for quetiapine-treated patients ranged from 0.8 kg for the 50 mg daily dose to 1.4 kg for the 600 mg daily dose (with lower gain for the 800 mg daily dose), compared to 0.2 kg for the placebo treated patients. The percentage of quetiapine treated patients who gained ≥7% of body weight ranged from 5.3% for the 50 mg daily dose to 15.5% for the 400 mg daily dose (with lower gain for the 600 and 800 mg daily doses), compared to 3.7% for placebo treated patients.Longer term relapse prevention trials had an open label period (ranging from 4 to 36 weeks) during which patients were treated with quetiapine, followed by a randomised withdrawal period during which patients were randomised to quetiapine or placebo. For patients who were randomised to quetiapine, the mean weight gain during the open label period was 2.56 kg, and by week 48 of the randomised period, the mean weight gain was 3.22 kg, compared to open label baseline. For patients who were randomised to placebo, the mean weight gain during the open label period was 2.39 kg, and by week 48 of the randomised period the mean weight gain was 0.89 kg, compared to open label baseline.In placebo-controlled studies in elderly patients with dementia-related psychosis, the incidence of cerebrovascular adverse events per 100 patient years was not higher in quetiapine-treated patients than in placebo-treated patients.In all short-term placebo-controlled monotherapy trials in patients with a baseline neutrophil count ≥1.5 X 109/L, the incidence of at least one occurrence of a shift to neutrophil count <1.5 X 109/L, was 1.9% in patients treated with quetiapine compared to 1.3% in placebo-treated patients. The incidence of shifts to >0.5 - <1.0 X 109/L was the same (0.2%) in patients treated with quetiapine as with placebo-treated patients. In all clinical trials (placebo-controlled, open-label, active comparator) in patients with a baseline neutrophil count ≥1.5 X 109/L, the incidence of at least one occurrence of a shift to neutrophil count <1.5 X 109/L was 2.9% and to <0.5 X 109/L was 0.21% in patients treated with quetiapine.In fixed dose short-term placebo-controlled clinical trials, quetiapine treatment was associated with dose-related decreases in thyroid hormone levels. In short-term placebo-controlled clinical trials, the incidence of potentially clinically significant shifts in thyroid hormone levels were: total T4: 3.4% for quetiapine versus 0.6% for placebo; free T4: 0.7% for quetiapine versus 0.1% for placebo; total T3: 0.54% for quetiapine versus 0.0% for placebo and free T3: 0.2% for quetiapine versus 0.0% for placebo. The incidence of shifts in TSH was 3.2% for quetiapine versus 2.7% for placebo. In short-term placebo-controlled monotherapy trials, the incidence of reciprocal, potentially clinically significant shifts in T3 and TSH was 0.0% for both quetiapine and placebo and 0.1% for quetiapine versus 0.0% for placebo for shifts in T4 and TSH. These changes in thyroid hormone levels are generally not associated with clinically symptomatic hypothyroidism. The reduction in total and free T4 was maximal within the first six weeks of quetiapine treatment, with no further reduction during long-term treatment. In nearly all cases, cessation of quetiapine treatment was associated with a reversal of the effects on total and free T4, irrespective of the duration of treatment. In eight patients, where TBG was measured, levels of TBG were unchanged.Cataracts/lens opacitiesIn a clinical trial to evaluate the cataractogenic potential of Seroquel (200-800 mg/day) versus risperidone (2-8 mg) in patients with schizophrenia or schizoaffective disorder, the percentage of patients with increased lens opacity grade was not higher in Seroquel (4%) compared with risperidone (10%), for patients with at least 21 months of exposure.Children and adolescents (10 to 17 years of age)The efficacy and safety of Seroquel was studied in a 3-week placebo controlled study for the treatment of mania (n= 284 patients from the US, aged 10-17). About 45% of the patient population had an additional diagnosis of ADHD. In addition, a 6-week placebo controlled study for the treatment of schizophrenia (n = 222 patients, aged 13-17) was performed. In both studies, patients with known lack of response to Seroquel were excluded. Treatment with Seroquel was initiated at 50 mg/day and on day 2 increased to 100 mg/day; subsequently the dose was titrated to a target dose (mania 400-600 mg/day; schizophrenia 400-800 mg/day) using increments of 100 mg/day given two or three times daily.In the mania study, the difference in LS mean change from baseline in YMRS total score (active minus placebo) was 5.21 for Seroquel 400 mg/day and 6.56 for Seroquel 600 mg/day. Responder rates (YMRS improvement ≥50%) were 64% for Seroquel 400 mg/day, 58% for 600 mg/day and 37% in the placebo arm. In the schizophrenia study, the difference in LS mean change from baseline in PANSS total score (active minus placebo) was 8.16 for Seroquel 400 mg/day and 9.29 for Seroquel 800 mg/day. Neither low dose (400 mg/day) nor high dose regimen (800 mg/day) quetiapine was superior to placebo with respect to the percentage of patients achieving response, defined as ≥30% reduction from baseline in PANSS total score. Both in mania and schizophrenia higher doses resulted in numerically lower response rates. No data are available on maintenance of effect or recurrence prevention in this age group.A 26-week open-label extension to the acute trials (n= 380 patients), with Seroquel flexibly dosed at 400-800 mg/day, provided additional safety data. Increases in blood pressure were reported in children and adolescents and increased appetite, extrapyramidal symptoms and elevations in serum prolactin were reported with higher frequency in children and adolescents than in adult patients (see section 4.4 Special warnings and precautions for use and section 4.8 Undesirable effects).
Extrapyramidal SymptomsIn a short-term placebo-controlled monotherapy trial with Seroquel in adolescent patients (13-17 years of age) with schizophrenia, the aggregated incidence of extrapyramidal symptoms was 12.9% for quetiapine and 5.3% for placebo, though the incidence of the individual adverse events (e.g. akathisia, tremor, extrapyramidal disorder, hypokinesia, restlessness, psychomotor hyperactivity, muscle rigidity, dyskinesia) did not exceed 4.1% in any treatment group. In a short-term placebo-controlled monotherapy trial with Seroquel in children and adolescent patients (10-17 years of age) with bipolar mania, the aggregated incidence of extrapyramidal symptoms was 3.6% for quetiapine and 1.1% for placebo. In a long-term open label study with Seroquel of schizophrenia and bipolar mania, the aggregated incidence of treatment-emergent EPS was 10%.
Weight Gain In short-term clinical trials with Seroquel in paediatric patients (10-17 years of age), 17% of quetiapine treated patients and 2.5% of placebo treated patients gained ≥7% of their body weight. When adjusting for normal growth over longer term, an increase of at least 0.5 standard deviation from baseline in Body Mass Index (BMI) was used as a measure of a clinically significant change; 18.3% of patients who were treated with quetiapine for at least 26 weeks met this criterion.
Suicide/Suicidal thoughts or Clinical worseningIn short-term placebo-controlled clinical trials with Seroquel in paediatric patients with schizophrenia, the incidence of suicide related events was 1.4% (2/147) for quetiapine and 1.3% (1/75) for placebo in patients <18 years of age. In short-term placebo-controlled trials with Seroquel in paediatric patients with bipolar mania, the incidence of suicide related events was 1.0% (2/193) for quetiapine and 0% (0/90) for placebo in patients <18 years of age.