Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036341 (schizophrenia)
 60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Refractoriness to treatment is a common problem in management of schizophrenics. Conventional pharmacotherapy is usually effective in controlling positive symptoms of the disease, such as delusions and hallucinations. However, they have restricted ability to affect negative symptoms (flat affect, social withdrawal) and to reverse functional disability and behavioral deviance. Furthermore, typical neuroleptics produce adverse effects, such as extrapyramidal symptoms and tardive dyskinesia. A new generation of antipsychotic agents with a low profile of side-effects and good tolerance has recently been developed and actively investigated. Seroquel (ICI 204-636), a dibenzoth azepine derivative, is a novel, putative, potential, atypical neuroleptic; it is a combined dopamine/ serotonin receptor antagonist. We report a 54-year-old man suffering from chronic therapy-resistant schizophrenia, with both positive and negative symptoms, who was successfully treated with Seroquel during 1 year.
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PMID:[Seroquel in a resistant schizophrenic with negative and positive symptoms]. 879 56

New neuroleptic drugs are being developed for the treatment of schizophrenia and other psychoses. Clozapine and risperidone are available for general use. Sertindole and olanzapine are nearing release. Seroquel and ziprazidone are in the final stages of study. This generation of drugs will provide advantages in the area of lower motor side effects and probably in improved negative symptom treatment.
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PMID:The new generation of antipsychotic drugs. 880 64

Treatment with standard antipsychotic medications causes side effects such as hyperprolactinemia and extrapyramidal symptoms. Because these side effects can cause noncompliance with antipsychotic medication and consequent relapse, they add to the morbidity of schizophrenia. A compound with antipsychotic efficacy but without the side effects of standard antipsychotic agents would improve compliance and treatment outcomes and enhance quality of life. Improved compliance, reduced relapse, and decreased hospitalization would also reduce the cost of treatment of schizophrenia. Seroquel (ICI 204,636), an atypical antipsychotic compound in Phase III development, was found to be well tolerated and effective in treating subjects with DSM-III-R schizophrenia in three Phase II clinical trials. Analysis of plasma prolactin concentrations obtained during these trials revealed that ICI 204,636 did not differ from placebo in its effect on plasma prolactin after up to 6 weeks of treatment; no significant difference was found in the degree of decline of plasma prolactin levels when subjects treated with ICI 204,636 and placebo were compared. A significant difference was found, however, between ICI 204,636- and chlorpromazine-treated subjects; prolactin levels in ICI 204,636-treated subjects fell to a greater degree than they did in chlorpromazine-treated subjects, however in all three trials, ICI 204,636 did not cause sustained elevation of prolactin.
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PMID:Plasma prolactin in schizophrenia subjects treated with Seroquel (ICI 204,636). 892 58

Risperidone and its active metabolite 9-OH-risperidone were compared to reference antipsychotic drugs (haloperidol, pipamperone, fluspirilene, clozapine, zotepine) and compounds under development (olanzapine, seroquel, sertindole, ORG-5222, ziprasidone) for in vitro binding to neurotransmitter receptors in brain tissue and on membranes of recombinant cells expressing cloned human receptors and for in vivo occupancy of neurotransmitter receptors in rat and guinea-pig brain following acute treatment (2 h., s.c.). An ex vivo autoradiography technique was applied to determine the receptor occupancy by the drugs administered in vivo. Of particular interest are the central 5HT2A receptors and D2-type receptors. Predominant 5HT2A receptor antagonism is supposed to add to an atypical profile of the antipsychotics (treatment of the negative symptoms, low incidence of extrapyramidal side effects). D2 antagonism is required the treatment of positive symptoms. A contribution of the new dopamine receptor subtypes D3 and in particular D4 receptors has been proposed. In vitro, all compounds, except the 'typical' antipsychotics haloperidol and fluspirilene, showed higher affinity for 5HT2A than for D2 receptors. Subnanomolar affinity for human 5HT2A receptors was observed for ORG-5222, sertindole, risperidone, 9-OH-risperidone and ziprasidone. Fluspirilene, ORG-5222, haloperidol, ziprasidone, risperidone, 9-OH-risperidone and zotepine displayed nanomolar affinity for human D2 receptors. Sertindole and olanzapine were slightly less potent. Pipamperone, clozapine and seroquel showed 2 orders of magnitude lower D2 affinity in vitro. Clozapine, but even more so pipamperone, displayed higher affinity for D4 than for D2 receptors. For most other compounds, D4 affinity was only slightly lower than their D2 affinity. Seroquel was totally devoid of D4 affinity. None of the compounds had nanomolar affinity for D1 receptors; their affinity for D3 receptors was usually slightly lower than for D2 receptors. In vivo, ORG-5222, risperidone, pipamperone, 9-OH-risperidone, sertindole, olanzapine, zotepine and clozapine maintained a higher potency for occupying 5HT2A than D2 receptors. Risperidone and ORG-5222 had 5HT2A versus D2 potency ratio of about 20. Highest potency for 5HT2A receptor occupancy was observed for ORG-5222 followed by risperidone and olanzapine. Ziprasidone exclusively occupied 5HT2A receptors. ORG-5222, haloperidol, fluspirilene and olanzapine showed the highest potency for occupying D2 receptors. No regional selectivity for D2 receptor occupancy in mesolimbic versus nigrostriatal areas was detected for any of the test compounds. Risperidone was conspicuous because of its more gradual occupancy of D2 receptors; none of the other compounds showed this property. The various compounds also displayed high to moderate occupancy of adrenergic alpha 1 receptors, except fluspirilene and ziprasidone. Clozapine, zotepine, ORG-5222 and sertindole occupied even more alpha 1 than D2 receptors. Clozapine showed predominant occupancy of H1 receptors and occupied cholinergic receptors with equivalent potency to D2 receptors. A stronger predominance of 5HT2A versus D2 receptor occupancy combined with a more gradual occupancy of D2 receptors differentiates risperidone and its 9-OH-metabolite from the other antipsychotic compounds in this study. The predominant 5HT2A receptor occupancy probably plays a role in the beneficial action of risperidone on the negative symptoms of schizophrenia, whereas maintenance of a moderate occupancy of D2 receptors seems adequate for treating the positive symptoms of schizophrenia. A combined 5HT2A and D2 occupancy and the avoidance of D2 receptor overblockade are believed to reduce the risk for extrapyra
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PMID:Risperidone compared with new and reference antipsychotic drugs: in vitro and in vivo receptor binding. 893 1

In radioligand binding studies, BIMG 80, a new putative antipsychotic, displayed good affinity at certain serotonin (5-HT1A, 5-HT2A, 5-HT6), dopamine (D1, D2L, D4), and noradrenergic (alpha1) receptors. The effect of acute subcutaneous BIMG 80, clozapine, haloperidol, risperidone, amperozide, olanzapine, and Seroquel was then investigated on dopamine release in medial prefrontal cortex, nucleus accumbens, and striatum in freely moving rats using the microdialysis technique. Four different neurochemical profiles resulted from the studies: (a) Systemic administration of BIMG 80, clozapine, and amperozide produced greater percent increases in dopamine efflux in medial prefrontal cortex than in the striatum or the nucleus accumbens. (b) Haloperidol induced a similar increase in dopamine concentrations in the striatum and nucleus accumbens with no effect in the medial prefrontal cortex. (c) Risperidone and olanzapine stimulated dopamine release to a similar extent in all brain regions investigated. (d) Seroquel failed to change significantly dopamine output both in the medial prefrontal cortex and in the striatum. Because an increase in dopamine release in the medial prefrontal cortex may be predictive of effectiveness in treating negative symptoms and in the striatum may be predictive of induction of extrapyramidal side effects, BIMG 80 appears to be a potential antipsychotic compound active on negative symptoms of schizophrenia with a low incidence of extrapyramidal side effects.
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PMID:BIMG 80, a novel potential antipsychotic drug: evidence for multireceptor actions and preferential release of dopamine in prefrontal cortex. 920 9

Five fixed doses of the atypical antipsychotic "Seroquel" (quetiapine) were evaluated to delineate a dose-response relationship, as measured by changes from baseline in Brief Psychiatric Rating Scale (BPRS), Clinical Global Impression (CGI), and Modified Scale for the Assessment of Negative Symptoms (SANS) summary scores, and to compare efficacy and tolerability opposite placebo and haloperidol. Three hundred sixty-one patients from 26 North American centers entered this double-blind, placebo-controlled trial with acute exacerbation of chronic schizophrenia (DSM-III-R). Patients who completed a single-blind, placebo washout phase were randomized to double-blind treatment with quetiapine (75, 150, 300, 600, or 750 mg daily), haloperidol (12 mg daily), or placebo and evaluated weekly for 6 weeks. At end point, significant differences (p < 0.05, analysis of covariance) in adjusted mean changes from baseline were identified between the four highest doses of quetiapine and placebo for BPRS total, BPRS positive-symptom cluster, and CGI Severity of Illness item scores and between quetiapine 300 mg and placebo for SANS summary score. Differences between quetiapine and haloperidol were not significant. Dose-response modeling showed significant linear and quadratic functions of quetiapine dose for all primary efficacy variables. Notably, no significant safety concerns were identified as dose increased. Quetiapine was no different from placebo across the dose range studied regarding incidence of extrapyramidal symptoms or change in prolactin concentrations. Quetiapine is well tolerated and clinically effective in the treatment of schizophrenia. It is both superior to placebo and comparable to haloperidol in reducing positive symptoms at doses ranging from 150 to 750 mg/day and in reducing negative symptoms at a dose of 300 mg/day.
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PMID:Multiple fixed doses of "Seroquel" (quetiapine) in patients with acute exacerbation of schizophrenia: a comparison with haloperidol and placebo. The Seroquel Trial 13 Study Group. 927 Sep

Prepulse inhibition (PPI) is a form of plasticity of the startle response in which presentation of a weak stimulus immediately before an intense startling stimulus reduces the resultant startle response. Deficits in PPI, an operational measure of sensorimotor gating, are observed in schizophrenia patients and can be modeled in rats by the psychotogen phencyclidine (PCP). PCP-induced deficits in PPI in rats are resistant to dopamine and serotonin antagonists but can be antagonized by antipsychotics such as clozapine, olanzapine and Seroquel. These latter antipsychotics have antagonistic actions at several receptors, including alpha-1 and alpha-2 adrenergic, M1 muscarinic and gamma-aminobutyric acid (GABA)-A receptors. Although the direct actions of PCP are thought to be mediated by noncompetitive antagonism of N-methyl-D-aspartate sites, PCP thereby indirectly activates multiple neurotransmitter systems, including those affected by the aforementioned antipsychotics. The present studies examined the possibility that an antagonist action at a particular receptor subtype might be responsible for the interaction between PCP and the clozapine-like antipsychotics by testing whether a selective antagonist at alpha-1, alpha-2, M1 or GABA-A receptors would prevent the PCP-induced deficit in PPI in rats. Animals were pretreated with either the alpha-1 antagonist prazosin (0, 0.5, 1.0 or 2.5 mg/kg), the alpha-2 antagonist RX821002 (0, 0.2 or 0.4 mg/kg), the M1 muscarinic antagonist pirenzepine (0, 10 or 30 mg/kg) or the GABA-A antagonist pitrazepin (0, 1.0 or 3.0 mg/kg) and then treated with either saline or PCP (1.5 mg/kg). Because prazosin was effective in blocking the effects of PCP, an additional experiment tested the possibility that prazosin (0, 1.0 or 2.5 mg/kg) would block the PPI deficits produced by the dopamine agonist apomorphine (0 or 0.5 mg/kg). After drug administration, animals were tested in startle chambers. PCP was found repeatedly to decrease PPI. Prazosin (1.0 and 2.5 mg/kg) blocked this deficit in two separate experiments but did not increase base-line PPI levels. The effects on PPI were dissociable from changes in startle reactivity. Furthermore, prazosin did not antagonize apomorphine-induced disruptions of PPI, which suggests that the antagonism of the PCP effect was not simply due to a generalized improvement of deficient PPI. The antagonists for alpha-2, for M1 and for GABA-A receptors had no effect on base-line PPI or on PCP-induced disruptions in PPI. These findings indicate that the PPI-disruptive effect of PCP may be mediated in part by alpha-1 adrenergic receptors and that antagonism of alpha-1 receptors may play a major role in mediating the blockade of PCP-induced deficits in PPI by certain antipsychotics.
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PMID:Phencyclidine-induced deficits in prepulse inhibition of startle are blocked by prazosin, an alpha-1 noradrenergic antagonist. 935 84

Quetiapine (Seroquel, ICI 204,636) is an atypical antipsychotic that is effective in the treatment of both positive and negative symptoms of schizophrenia, and has a low propensity to cause extrapyramidal symptoms. The compound has a relatively short plasma elimination half-life (approximately 7 h). However, since dopamine D2 receptor occupancies correlate poorly with plasma concentrations of antipsychotics, plasma elimination half-life may not predict either duration of clinical effect or dosing frequency. Accordingly, the efficacy and tolerability of three dosing regimens (450 mg/day given in two or three divided doses daily, and 50 mg/day given twice daily) were compared in a 6-week, double-blind, randomized, multicentre, parallel-group study. The study recruited hospitalized men and women aged 18-65 years meeting DSM-IIIR criteria for acute exacerbation of chronic or subchronic schizophrenia. Six hundred and eighteen patients were randomly assigned to treatment with quetiapine 150 mg tid (n = 209), 225 mg bd (n = 200), or a comparator dose of 25 mg bd (n = 209). At day 42, the last day of randomized treatment and the primary timepoint for efficacy, quetiapine 450 mg/day was more effective than 50 mg/day: 225 mg bd was consistently superior to 25 mg bd in all measures of efficacy (total BPRS, P = 0.006; CGI severity, CGI improvement and SANS, P < 0.03), and 150 mg tid was statistically significantly superior to 25 mg bd with respect to BPRS total score (P = 0.05). The 225 mg bd and 150 mg tid groups were not significantly different from each other with respect to any efficacy measure. Quetiapine was generally well tolerated. Extrapyramidal symptom (EPS) adverse events were generally rare, and occurred with similar frequencies in the two 450 mg/day groups. Quetiapine was not associated with sustained increases in plasma prolactin at any dose. These data support the atypical profile developed from preclinical studies and show that quetiapine is an effective, well tolerated antipsychotic that can be given twice daily.
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PMID:A comparison of bd and tid dose regimens of quetiapine (Seroquel) in the treatment of schizophrenia. 963

Quetiapine has recently been approved for treatment of psychotic disorders. In short term (6 weeks) trials this atypical antipsychotic was shown to be as efficacious as the standard antipsychotics for the treatment of the positive symptoms of schizophrenia without causing any extrapyramidal symptoms or increase in the prolactin levels. Its efficacy for treating the negative symptoms was variable. Preliminary observations suggest its potential to improve the cognitive deficits of schizophrenia. It is metabolized by the p450 CYP 3A4 system with an estimated elimination half life of 6 hours. The optimal treatment is 300 mg to 400 mg/day in two to three divided oral doses. The most common side effects include dizziness, hypotension, somnolence and weight gain. Changes in the ECG, the thyroid hormone and hepatic enzymes levels appear to be clinically insignificant. Quetiapine interacts with phenytoin, carbamazepine, barbiturates, rifampin and glucocorticoids; and coadministration with these drugs may require dosage adjustment. Doses need not be adjusted when fluoxetine, imipramine, haloperidol and resperidone are coadministered. Quetiapine may enhance the effects of antihypertensive agents and may antagonize those of levodopa and dopamine. Long term efficacy of quetiapine has not been determined. Also undetermined are its effectiveness for treating the first episode and treatment-refractory schizophrenia. Data suggest that quetiapine may be used for the management of psychotic disorders in patients who may not tolerate the side effects of the typical antipsychotics and clozapine. It may also be helpful in patients whose psychotic manifestations did not adequately respond to risperidone and olanzapine.
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PMID:Quetiapine: a new atypical antipsychotic. 964 17

Treating schizophrenia is expensive. Preventing rehospitalization of patients with schizophrenia provides an attractive opportunity for cost savings, especially for patients with 'revolving-door' or multiple-episode schizophrenia. Reducing the occurrence of extrapyramidal symptoms and other adverse events associated with standard antipsychotic agents may increase compliance and reduce the rate of rehospitalization of patients with schizophrenia. Quetiapine ('Seroquel', ICI 204,636, Zeneca Pharmaceuticals) is a new dibenzothiazepine antipsychotic agent with a low propensity for extrapyramidal symptoms. We describe here a unique methodology to compare quetiapine with usual-care medications in real-world treatment settings. The trial objective is to determine if therapy with this new atypical antipsychotic agent can reduce the rate of rehospitalization and, therefore, treatment costs. Using two secondary medical-claims databases, we defined the minimal threshold for revolving-door status as 1.0 admission per year; this definition allows our trial to focus on the subpopulation of schizophrenic patients with the greatest potential for cost savings by either the new atypical antipsychotic quetiapine or usual-care therapy. We describe here the approach used in our trial.
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PMID:Medical-claims databases in the design of a health-outcomes comparison of quetiapine ('Seroquel') and usual-care antipsychotic medication. 969 Mar 34


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