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PubMed2006

Tissue distribution of quetiapine in 20 cases in Virginia.

Quetiapine fumarate (Seroquel) is a dibenzothiazepine psychotropic agent that was introduced in 1997 for treating psychoses. Quetiapine is being found with increasing frequency in postmortem cases in Virginia. We report the postmortem results and histories of 20 quetiapine cases from the Office of the Chief Medical Examiner in Virginia covering the period 1999 through 2004. Quetiapine was extracted from blood using a basic drug solid-phase extraction (SPE) and identified by full scan electron impact gas chromatography-mass spectrometry (GC-MS). Quetiapine quantification was accomplished by forming the trimethylsilyl derivative with bis(trimethylsilyl)trifluoracetamide/trimethylchlorosilane and using selected ion monitoring GC-MS. The quetiapine trimethylsilyl derivative ions acquired were m/z 210, 239, and 322. Methapyrilene was the internal standard, and ions m/z 97 and 58 were monitored. The method was linear from 0.1 to 5.0 mg/L with a limit of quantitation of 0.1 mg/L. The quetiapine mean and range of concentrations found in each tissue are as follows: peripheral blood, 7.7 mg/L (0.14-37 mg/L, n = 17); heart blood, 23.63 mg/L (0.53-76 mg/L, n = 4); liver, 91 mg/Kg (1.1-510 mg/Kg, n = 19); bile, 44 mg/L (6.0-96 mg/L, n = 4); urine, 15 mg/L (1.9-37 mg/L, n = 8); gastric, 897 mg total (3.5-3960 mg, n = 7); and vitreous, 1.4 mg/L (0.2-3.2 mg/L, n = 5). The average of all blood concentrations in 18 cases in which quetiapine contributed to the cause of death was 7.95 mg/L (0.4-76 mg/L). The manner of death in 13 of those cases was suicide, two were undetermined, and three were accidents. In two cases in which quetiapine was an incidental finding, the blood concentrations were 0.14 and 1.0 mg/L. Quetiapine and other toxicological findings are presented with the cause and manner of death to assist in interpreting future quetiapine findings in postmortem samples.

Adolescent↗
PubMed2000

Remission of severe tardive dyskinesia in a schizophrenic patient treated with the atypical antipsychotic substance quetiapine.

In a single inpatient case study, a schizophrenic patient with tardive dyskinesia after prolonged treatment with typical neuroleptics was treated with the new atypical neuroleptic quetiapine, a dibenzothiazepin-derivative. Within 2 weeks of treatment with quetiapine, symptoms of tardive dyskinesia improved; 10 weeks after starting treatment tardive dyskinesia stopped completely. Over the same period, dopamine D2 receptor occupancy decreased substantially, as measured by IBZM-SPECT after 14 and 77 days of treatment.

Adult↗
PubMed1999

Focus on quetiapine.

Quetiapine fumarate is a novel dibenzothiazepine antipsychotic developed by Zeneca. It is marketed under the trade name 'Seroquel'. Quetiapine is well tolerated and clinically effective in the treatment of schizophrenia. The initial hope of investigators was that quetiapine would have antipsychotic potential and that it might share some of the properties of clozapine without its toxicity to white blood cells. The effective dosage range is usually 300-450 mg/day split into two doses. The dose is titrated upwards from 25 mg twice daily from day 1 to 300 mg/day on day 4. Elderly patients or patients with liver problems should be started on lower doses. It is both superior to placebo and comparable to haloperidol in reducing positive symptoms at doses ranging from 150 mg/day to 750 mg/day, and is an effective treatment for negative symptoms. Somnolence is the most common adverse event. Abnormalities of the QT interval on ECG appear very infrequently and there is no need for a baseline ECG or blood pressure monitoring, as used to be the case with sertindole. There is no need for haematological monitoring as with clozapine. Quetiapine, across the full dosage range, is associated with no greater extrapyramidal symptoms than placebo. Quetiapine's general efficacy and side-effect profile suggest that, unless there are unforeseen post-marketing complications, it deserves a major place in the initial and long-term management of schizophreniform disorders.

Animals↗
PubMed2006

Quetiapine: efficacy, tolerability and safety in schizophrenia.

Quetiapine, a dibenzothiazepine derivative, is an atypical antipsychotic, multireceptor antagonist that has a preclinical profile similar to clozapine. Randomized studies have demonstrated the efficacy of quetiapine relative to placebo in the treatment of acute relapse and the long-term management of schizophrenia. Quetiapine is generally well tolerated relative to other antipsychotic medications, although side effects include sedation, orthostatic hypotension, anticholinergic and metabolic side effects. The purpose of this article is to critically review the current literature on quetiapine with an emphasis on emergent themes and key findings in the use of this agent for the treatment of schizophrenia. There are also continued efforts to understand, predict and manage the side-effect risk with quetiapine.

Antipsychotic Agents↗
PubMed2000

Quetiapine: a review of its safety in the management of schizophrenia.

Quetiapine, a dibenzothiazepine derivative, is a atypical antipsychotic which has greater in vitro binding affinity for serotonin 5-HT2 receptors than for dopamine D2 receptors. Quetiapine effectively treats both the positive and the negative symptoms of schizophrenia and is also associated with an incidence of extrapyramidal symptoms no greater than placebo across the entire dose range. In addition, it does not cause persistent hyperprolactinaemia. Quetiapine is associated with high levels of patient acceptability and satisfaction, which may result from its combination of efficacy and relatively benign adverse effect profile. The drug is well tolerated and has a low propensity to cause adverse events both during acute and long term treatment in the adult populations. The adverse effect profile of quetiapine makes the drug advantageous for patient populations who are susceptible to the adverse effects of drugs. Indeed, preliminary data show quetiapine to be very well tolerated in the elderly. Overdoses of quetiapine of up to 20g have been reported; however, with appropriate management in an intensive care setting there have been no reported fatalities. Quetiapine is metabolised by the cytochrome P450 3A4 isoenzyme, and the dose may need to be adjusted if quetiapine is co-administered with drugs which affect the activity of this isoenzyme. Overall, quetiapine has a favourable risk-benefit profile that should make it a valuable first-line agent in the treatment of schizophrenia.

Adolescent↗
PubMed2001

Clinical pharmacokinetics of quetiapine: an atypical antipsychotic.

Quetiapine is a dibenzothiazepine derivative that has been evaluated for management of patients with the manifestations of psychotic disorders. In pharmacokinetic studies in humans, quetiapine was rapidly absorbed after oral administration, with median time to reach maximum observed plasma concentration ranging from 1 to 2 hours. The absolute bioavailability is unknown, but the relative bioavailability from orally administered tablets compared with a solution was nearly complete. Food has minimal effects on quetiapine absorption. The drug is approximately 83% bound to serum proteins. Single and multiple dose studies have demonstrated linear pharmacokinetics in the clinical dose range (up to 375mg twice daily). The drug is eliminated with a mean terminal half-life of approximately 7 hours. The primary route of elimination is through hepatic metabolism. In vitro studies show that quetiapine is predominantly metabolised by cytochrome P450 (CYP) 3A4. After administration of [14C]quetiapine, approximately 73% of the radioactivity was excreted in the urine and 21% in faeces. Quetiapine accounted for less than 1% of the excreted radioactivity. 11 metabolites formed through hepatic oxidation have been identified. Two were found to be pharmacologically active, but they circulate in plasma at 2 to 12% of the concentration of quetiapine and are unlikely to contribute substantially to the pharmacological effects of the drug. The pharmacokinetics of quetiapine do not appear to be altered by cigarette smoking. Oral clearance declines with age, and was reduced in 2 of 8 patients with hepatic dysfunction but not in patients with renal impairment. Quetiapine has no effect on the in vitro activity of CYP1A2, 2C9, 2C19, 2D6 and 3A4 at clinically relevant concentrations. The lack of effect of quetiapine on hepatic oxidation was confirmed in vivo by the lack of effect of quetiapine on antipyrine disposition. Quetiapine had no effect on serum lithium concentration. Phenytoin and thioridazine increase the clearance of quetiapine, and ketoconazole decreases clearance. No clinically significant effects of cimetidine, haloperidol, risperidone or imipramine on the pharmacokinetics of quetiapine were noted. Quetiapine dosage adjustment, therefore, may be necessary when coadministered with phenytoin, thioridazine or other potent CYP3A4 inducers or inhibitors. The relationship between the therapeutic effects and the plasma concentrations of quetiapine has been investigated in a multicentre clinical trial. There was no statistically significant association between trough plasma quetiapine concentration and clinical response as measured by traditional assessments of psychotic symptom severity. Subsequent clinical studies of the plasma concentration versus effect relationships for quetiapine may help to further define guidelines for dosage regimen design.

Adolescent↗
PubMed2004

Quetiapine. A review of its use in the management of schizophrenia.

Quetiapine (Seroquel), a dibenzothiazepine derivative, is an atypical antipsychotic with demonstrated efficacy in acute schizophrenia. In short-term, randomised, double-blind trials, it was usually more effective than placebo, and was generally effective against both positive and negative symptoms. Overall, quetiapine (up to 750 mg/day) was at least as effective as chlorpromazine (up to 750 mg/day) and had similar efficacy to haloperidol (up to 16 mg/day) in patients with acute schizophrenia in randomised, double-blind trials; it was at least as effective as haloperidol 20 mg/day in patients with schizophrenia unresponsive or partially responsive to previous antipsychotic treatment. Improvements in overall psychopathology and positive and negative symptoms with quetiapine (up to 800 mg/day) were similar to those with risperidone (up to 8 mg/day) or olanzapine (15 mg/day) [interim analysis]. Efficacy was maintained for at least 52 weeks in open-label follow-up studies in adult and elderly patients. Quetiapine improved cognitive function versus haloperidol, and depressive symptoms and hostility/aggression versus placebo. Quetiapine is well tolerated. It is associated with placebo-level incidence of extrapyramidal symptoms (EPS) across its entire dose range, appears to have a low risk for EPS in vulnerable patient groups (e.g. the elderly, adolescents or patients with organic brain disorders) and has a more favourable EPS profile than risperidone. Irrespective of dose, quetiapine, unlike risperidone and amisulpride, does not elevate plasma prolactin levels compared with placebo, and previously elevated levels may even normalise. Quetiapine appears to have minimal short-term effects on bodyweight and a favourable long-term bodyweight profile. Preliminary studies indicate that there is a high level of patient acceptability and satisfaction with quetiapine. In conclusion, quetiapine has shown efficacy against both positive and negative symptoms of schizophrenia, and has benefits in improving cognitive deficits, affective symptoms and aggression/hostility. The beneficial effects of quetiapine have been maintained for at least 52 weeks. Quetiapine was effective and well tolerated in hard-to-treat patients, and may be of particular use in these individuals. It is at least as effective as standard antipsychotics and appears to have similar efficacy to risperidone and olanzapine. The relative risk/benefit profile of quetiapine compared with other atypical antipsychotics requires further research in head-to-head trials, although quetiapine's relatively benign tolerability profile distinguishes it from other commonly used atypical agents, particularly with respect to bodyweight, EPS and plasma prolactin levels. Overall, quetiapine has an excellent risk/benefit profile and is a suitable first-line option for the treatment of schizophrenia.

Dibenzothiazepines↗
PubMed1998

Loss of consciousness from acute quetiapine overdosage.

BACKGROUND: Quetiapine (Seroquel) is a new atypical antipsychotic agent developed for the treatment of schizophrenia. This dibenzothiazepine derivative possesses high affinity for 5-HT2 receptors with lower affinity for D1 and D2 dopamine receptors. In comparison to other antipsychotic agents, quetiapine has less antimuscarinic and alpha1 antagonist receptor activity. Overdose reports outside of clinical trials are limited. We report an intentional overdose of quetiapine by a schizophrenic. CASE REPORT: A 26-year-old female presented to the emergency department following an alleged ingestion of greater than 10,000 mg of quetiapine. At 1 1/2 hours postingestion, the patient was awake, ambulatory, and responded to verbal stimuli. At 2 1/2 hours postingestion, the patient experienced a decreased level of consciousness and responded only to deep pain. Physical findings included sinus tachycardia, pupils 3-4 mm and sluggish, and BP 135/70. Within 16 hours, the patient became awake and alert and was subsequently extubated. Serum electrolytes and blood count were unremarkable. The electrocardiogram at 18 hours postingestion showed a sinus tachycardia, which lasted for approximately 40 hours postingestion. A follow-up electrocardiogram at 42 hours postingestion was normal. CONCLUSION: This ingestion resulted in the loss of consciousness with need for airway protection and persistent tachycardia. Major overdoses of quetiapine warrant close observation in an intensive care setting.

Adult↗
PubMed2002

Quetiapine: preclinical studies, pharmacokinetics, drug interactions, and dosing.

Quetiapine is a novel dibenzothiazepine atypical antipsychotic. Quetiapine shows affinity for various neurotransmitter receptors including serotonin, dopamine, histamine, and adrenergic receptors and has binding characteristics at the dopamine-2 receptor similar to those of clozapine. In animal models, the drug has a preclinical profile suggestive of antipsychotic activity with a reduced tendency to cause extrapyramidal symptoms (EPS) and sustained prolactin elevation. For example, quetiapine alters neurotensin neurotransmission and c-fos expression in limbic but not motor brain regions. The drug also demonstrates clozapine-like activity in a range of behavioral and biochemical tests and may possess neuroprotective properties. In humans, quetiapine exhibits linear pharmacokinetics with a mean terminal half-life of 7 hours. The primary route of elimination of quetiapine is through hepatic metabolism. Although not affected by smoking, alterations in quetiapine disposition due to age or hepatic impairment are manageable by appropriate dosage reduction. The optimal dosing range for quetiapine is 150 to 750 mg/day, and recent results suggest that once-daily dosing may be suitable for some patients. Finally, imaging studies with positron emission tomography confirm significant differences between quetiapine and typical antipsychotics that may be indicative of their differences in mechanism of action and propensity for producing EPS.

Animals↗
PubMedDate not supplied

Quetiapine, an atypical antipsychotic.

The discovery of antipsychotic agents in the 1950s revolutionized the treatment of schizophrenia. A large body of evidence supports the dopamine D2 receptor antagonist's efficacy in the treatment of psychotic symptoms. However, the advent of newer agents seems to point to a more complex interaction of neurotransmission in the pathophysiology of schizophrenia. In fact, a defining characteristic of atypical agents is a higher ratio of serotonin (5HT2) receptor blockade to D2 receptor blockade. Clozapine was the first atypical agent to be introduced; it was followed by risperidone, olanzapine, and now quetiapine, which is a dibenzothiazepine derivative structurally related to clozapine and olanzapine.

Antipsychotic Agents↗
PubMed1995

Peroxidase-catalysed oxidation of different dibenzazepine derivatives.

According to a recent hypothesis suggesting the potential role of free radical formation in the clozapine-induced agranulocytosis, we have evaluated the susceptibility to the peroxidase-mediated oxidation of different dibenzazepine analogues. On the one hand, compounds with an arylamine group such as clozapine or isoclozapine present a high reactivity in the horseradish peroxidase or myeloperoxidase systems and, on the other hand, fluperlapine, though known to induce agranulocytosis, and other dibenzothiazepine and dibenzoxazepine derivatives appear insensitive to oxidation. Consequently, among tricyclic derivatives, the way of diaryloxa- and diarylthiazepine compounds could be an alternative for the development of safer drugs such as antipsychotics.

Catalysis↗
PubMed2000

Biotransformation of post-clozapine antipsychotics: pharmacological implications.

The need to develop new antipsychotics that have fewer motor adverse effects and offer better treatment of negative symptoms has led to a new generation of drugs. Most of these drugs undergo extensive first-pass metabolism and are cleared almost exclusively by metabolism, except for amisulpride whose clearance is largely due to urinary excretion. Risperidone has metabolic routes in common with ziprasidone but shows differences in regard to other main pathways: the benzisoxazole moiety of risperidone is oxidised by cytochrome P450 (CYP) 2D6 to the active 9-hydroxyrisperidone, whereas the benzisothiazole of ziprasidone is primarily oxidised by CYP3A4, yielding sulfoxide and sulfone derivatives with low affinity for target receptors in vitro. Olanzapine, quetiapine and zotepine also have some common metabolic features. However, for the thienobenzodiazepine olanzapine a main metabolic route is direct conjugation at the benzodiazepine nucleus, whereas for the dibenzothiazepine quetiapine and the dibenzothiepine zotepine it is CYP3A4-mediated oxidation, leading to sulfoxidation, hydroxylation and dealkylation for quetiapine, but N-demethylation to the active nor-derivative for zotepine. Although the promising benzisoxazole (iloperidone) and benzisothiazole (perospirone) antipsychotics share some metabolic routes with the structurally related available drugs, they too have pharmacologically relevant compound-specific pathways. For some of the new antipsychotics we know the isoenzymes involved in their main metabolic pathways and the endogenous and exogenous factors that, by affecting enzyme activity, can potentially modify steady-state concentrations of the parent drug or its metabolite(s), but we know very little about others (e.g. amisulpride isomers, nemonapride). For yet others, information is scarce about the activity of the main metabolites and whether and how these contribute to the effect of the parent drug. Aging reduces the clearance of most antipsychotics, except amisulpride (which requires further evaluation) and ziprasidone. Liver impairment has little or no effect on the pharmacokinetics of olanzapine, quetiapine, risperidone (and 9-hydroxy-risperidone) and ziprasidone, but information is lacking for amisulpride. Renal impairment significantly reduces the clearance and prolongs the elimination half-life of amisulpride and risperidone. Again, studies are still not available for some drugs (zotepine) and have focused on the parent drug for others (olanzapine, quetiapine, ziprasidone) despite the fact that renal impairment would be expected to lower the clearance of more polar metabolites. Addressing these issues may assist clinicians in the design of safe and effective regimens for this group of drugs, and in selecting the best agent for each specific population.

Antipsychotic Agents↗
PubMed1992

Neurochemical and pharmacological properties of tianeptine, a novel antidepressant.

Tianeptine is a tricyclic antidepressant with an unusual chemical structure (a long lateral chain grafted on to a substituted dibenzothiazepin nucleus), and with biochemical and animal-behavioural properties which are strikingly different from those of classical tricyclics. Unlike the latter, which decrease serotonin (5-HT) uptake, acute and chronic tianeptine treatment enhances 5-HT uptake in rat brain and in rat and human platelets ex vivo. In vivo, tianeptine potentiates the depletion of rat brain 5-HT by 4-methyl-alpha-ethyl metatyramine and increases rat hippocampal 5-HIAA; 5-HT uptake inhibitors (e.g. fluoxetine) have opposite effects. On iontophoretic injection into CA1 pyramidal cells, tianeptine shortens the period of neuronal hypoactivity caused by GABA or 5-HT, whereas other tricyclics prolong it, and it enhances attention, learning, and memory in laboratory animals, while classical tricyclics have opposite effects. However, the relationships between these effects of tianeptine in animal experiments and their relevance to clinical findings remain to be determined.

Animals↗
PubMed1988

Position of tianeptine among antidepressive chemotherapies.

The advent of a new antidepressant is always received with both interest and scepticism by clinicians. No new compound has yet been shown to be more efficient than imipramine in the treatment of depression. In determining the position of a compound among the antidepressants, four levels are to be considered: (a) Chemical family: Tianeptine is a tricyclic compound of dibenzothiazepine type. It is the only representative of this subgroup. (b) Biochemical activities: Tianeptine increases the presynaptic uptake of serotonin after single as well as repeated administration; but this action is not linked to any effect on the 5-HT post-synaptic systems. Electrophysiological modifications are observed in the locus coeruleus (noradrenergic) at 2.5 times higher doses; nevertheless, the essential action involves the serotoninergic systems. Tianeptine has no affinity for alpha 1 adrenergic and H1 antihistaminic receptors; this affinity is responsible in a large part for the sedative anxiolytic properties of antidepressants. Tianeptine has no affinity for the muscarinic receptors. It has secured its place among the non-anticholinergic antidepressants. The mechanism of action or the therapeutic profile cannot be inferred from this original biochemical profile. (c) In clinical trials, the double-blind trials confirm the antidepressant efficacy in essentially neurotic depressive syndromes, similar to that of imipramine, nomifensine, amitriptyline. They do not show a shorter onset time of antidepressant activity. The therapeutic profile appears to be neither stimulating nor sedative. Some arguments are in favor of an anxiolytic activity. Others favor a more psychotonic profile. Tianeptine can be classified among the mid-position antidepressants. (d) With respect to clinical acceptability, tianeptine has no anticholinergic effect and no cardiovascular effect.

Antidepressive Agents, Tricyclic↗
PubMed1980

Studies on the kinetic properties of tryptophan hydroxylase of rabbit mesencephalon and pons medulla. Effect of long-term treatment with neuroleptics and antidepressants.

Tryptophan hydroxylase activity was measured in mesencephalon and pons medulla of rabbits receiving reserpine or other neuroleptics which are chemically related to phenothiazines (chlorpromazine), dibenzothiazepine (imipramine), dibenzobicyclooctadiene (maprotiline), dibenzothiepines (methiothepin), butyrophenones (haloperidol) and tetrahydro-isoquinolines (nomifensine). Chronic i.m. administration of imipramine and nomifensine increased the affinity of mesencephalic tryptophan hydroxylase for tryptophan. The injection of chlorpromazone increased the enzyme activity significantly in comparison to control values.

Animals↗
PubMed2000

Quetiapine for schizophrenia.

BACKGROUND: Quetiapine is a novel atypical antipsychotic with low propensity for movement disorder adverse effects. It is used for treatment of schizophrenia and other psychoses. OBJECTIVES: To determine the effects of quetiapine for schizophrenia in comparison to placebo, classical and other atypical antipsychotics. SEARCH STRATEGY: Electronic searches of Biological Abstracts (1982-1997), CINAHL (1982-1997), the Cochrane Library (1998, Issue 1), the Cochrane Schizophrenia Group's Register of trials (1998), EMBASE (1980-1998), MEDLINE (1966-1998), PsycLIT (1974-1997), SocioFile (1974-1997) and many conference proceedings and hand searches of specific journals were undertaken. Zeneca Pharmaceuticals was contacted for information regarding unpublished trials. SELECTION CRITERIA: All controlled trials where adults with schizophrenia or similar illnesses were randomised to quetiapine, placebo or other neuroleptic drugs and where clinically relevant outcomes were reported. DATA COLLECTION AND ANALYSIS: Citations and, where possible, abstracts were independently inspected by reviewers, papers ordered, re-inspected and quality assessed. Data were also independently extracted. For homogeneous dichotomous data the Peto odds ratio (OR), 95% confidence interval (CI) and, where appropriate, the number needed to treat (NNT) was calculated on an intention-to-treat basis. MAIN RESULTS: Seven trials of short duration are included (31 reports) and seven are excluded (15 reports). Apart from that of 'leaving the study early', all other results may be prone to bias and should be viewed with caution since dropout rates are high (48-61%) in each arm of all studies. There are data suggesting less people allocated quetiapine leave the study early (53%) than those in the placebo group (61%) (OR 0.67 CI 0.48-0. 95). Data incorporating considerable assumptions about the many people who left early suggest that global state and psychotic symptoms - both positive and negative - may be more helped by quetiapine than placebo. Although some of these data reach statistical significance their clinical importance is difficult to interpret. While the incidences of extrapyramidal side effects are not different between quetiapine and placebo, side effects such as dizziness and dry mouth are more prevalent in the quetiapine treated group. High proportions of trial participants also leave when quetiapine is compared to chlorpromazine or haloperidol (57% by six weeks). Quetiapine is as potent as chlorpromazine and haloperidol as regards global and mental state but it may cause higher incidences of dry mouth and sleepiness. Extrapyramidal side effects are the same as those of chlorpromazine but may be less than haloperidol. High dose quetiapine is better than low dose quetiapine with regard to leaving the study early, and limited data suggest that the higher dose is also better at marginally improving global state (n = 1, OR 0.70, CI 0.50-0.99, NNT 11). There are no clear differences between high and low dose groups in respect of extrapyramidal side effects. REVIEWER'S CONCLUSIONS: The high dropout rates are a large problem in interpreting any results other than 'leaving the study early' since about half the data were not available at the end of studies. Before quetiapine's use can be recommended, we need more large, well conducted trials that provide short, medium and long term outcomes relevant to carers and clinicians.

Adult↗