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)

The role of risperidone in the management of treatment-resistant schizophrenia remains unclear. We describe two patients with treatment-resistant schizophrenia characterized by unremitting delusions, thought disorder and self-neglect who had a sustained improvement in their symptoms soon after starting risperidone. Risperidone may be a suitable alternative to clozapine in some patients unresponsive to conventional antipsychotics.
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PMID:The use of risperidone in treatment-resistant schizophrenia: two case reports. 873 18

Although antipsychotic drugs are effective in treating the so-called positive features of schizophrenia, between one-quarter and one-third of patients respond poorly. Furthermore, the incidence of adverse effects is high, especially those reflecting disruption of extrapyramidal function, and is a major source of non-compliance. There is a clear need for new compounds that are more efficacious and/or better tolerated. Until recently, the classical dopamine hypothesis, with its emphasis on D2 blockade as the key mechanism of antipsychotic action, dominated drug development, though the emphasis is now shifting. Three 'new' antipsychotics have reached the international market in the past 5 years-the newly rehabilitated clozapine and the genuinely new remoxipride and risperidone. Claims of enhanced tolerability have been made for each of these, but as none is free from adverse effects, their place in treatment can only be meaningfully established in relation to the efficacy of each in different clinical situations. Clozapine has an extensive profile of general, nonhaematological adverse effects which is slightly different in emphasis from, but comparable in incidence to, that of chlorpromazine. There is a 0.8% risk of agranulocytosis in the first year of exposure, which can be fatal, though the boundary separating it from other (especially phenothiazine) antipsychotics in this regard is becoming increasingly blurred. It has a clearly diminished liability to cause extrapyramidal adverse effects. Its proven efficacy in operationally defined treatment-resistant schizophrenia and in patients intolerant to the extrapyramidal adverse effects of standard drugs establishes its credentials for advantage in these groups. There is on present evidence, however, only a hint of enhanced efficacy in acute schizophrenia: this requires further investigation. Open maintenance studies provide impressive data on long term outcome, especially in terms of quality-of-life parameters, but this issue requires to be addressed in blind, randomised trials. Until such additional information is forthcoming the risks and consequent costs would not justify extension of its use. The evidence to date is that reported benefits in so-called negative features probably reflect its favourable neurological profile. While the advantages of clozapine are undoubted, they remain as yet restricted to selected patient groups. Remoxipride has a good general tolerability profile, its special strength being its low sedative effect. However, its reported association with aplastic anaemia has severely restricted its use, and regular haematological monitoring is required. Although remoxipride appears to have a lower liability to produce extrapyramidal adverse effects than the high potency haloperidol, its benefits relative to other low potency compounds in this regard remain unproven. The only obvious situation in which its risks and consequent costs would be justified would seem to be patients with established compliance problems as a result of intrusive sedation with standard drugs. The position of other benzamides such as raclopride and amisulpride remains to be established. Risperidone, perhaps from its antiadrenergic actions, has more in the way of cardiovascular adverse effects than haloperidol, though these can be obviated by graded early exposure. It may also be associated with greater weight gain. Otherwise it appears to be well tolerated. In comparison with haloperidol, it appears to be associated with a lower prevalence of acute extrapyramidal adverse effects in dosages < or = 10 mg/day, the most potentially important component of which is its reportedly insignificant likelihood of promoting akathisia. These conclusions emerge from comparisons with haloperidol in doses many might consider somewhat high. The question of the advantage of risperidone over low or milligram-equivalent haloperidol regimens remains open.(ABSTRACT TRUNCATED)
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PMID:Adverse effects of antipsychotic agents. Do newer agents offer advantages? 873 14

Risperidone has antiserotonergic and antidopaminergic properties that may make it more effective than conventional antipsychotic agents in the treatment of the negative symptoms of schizophrenia. Clinical trials in chronic schizophrenic patients have shown trends in favor of risperidone in the control of negative symptoms compared with haloperidol, perphenazine or zuclopenthixol, but the differences were not consistently statistically significant. A meta-analysis of the pooled results from six double-blind trials showed that risperidone at doses ranging from 4 to 8 mg/day had a significantly (p < 0.004) higher negative symptom response rate, defined as the percentage of patients with a 20% or more reduction in scores on the negative subscale of the Positive and Negative Syndrome Scale, than patients receiving active controls. The combined patient population treated with 4-8 mg/day of risperidone was 1.43 times more likely to have had a clinical response on the negative symptom subscale than the combined population treated with haloperidol, perphenazine or zuclopenthixol.
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PMID:Risperidone in the treatment of negative symptoms of schizophrenia: a meta-analysis. 874 41

This article reviews the evidence for the efficacy and effectiveness of risperidone in persons with schizophrenia. Nine published double-blind studies compare risperidone with another antipsychotic medication and/or placebo. All were conducted in the acute phase of illness. Risperidone's antipsychotic efficacy is shown to be consistently superior to that of placebo and at least comparable to that of haloperidol and perphenazine for patients in the acute phase of schizophrenia. Further research is necessary to determine the effectiveness of risperidone and its efficacy both as a maintenance treatment and in treatment-refractory and deficit-state patients.
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PMID:Risperidone: efficacy and safety. 874 87

Risperidone was compared with antipsychotics hitherto used for in vitro receptor binding using animal brain or cloned (human) receptors and in vivo receptor occupancy in rat and guinea pig brain following acute treatment. Both in vitro and in vivo, risperidone, 9-OH-risperidone, SM-9018, clozapine and clocapramine showed higher affinity for 5-HT2A- than for D2-receptors, whereas mosapramine, haloperidol, bromperidol and nemonapride had a slight to strong preference for D2- compared to 5-HT2A-receptors. In vivo, risperidone showed the highest potency for 5-HT2A-receptor occupancy; To obtain the same extent of D2-receptor occupancy, a 19-times higher dosage was required. 9-OH-Risperidone, the principal active metabolite of risperidone, showed a receptor occupancy profile comparable to that of risperidone. No regional selectivity for D2-receptor occupancy in mesolimbic vs nigrostriatal areas was detected for any of the compounds. Risperidone differed from the other compounds by the remarkably shallow slope of its D2-receptor dose-occupancy curve. A greater predominance of 5-HT2A-receptor vs D2-receptor occupancy and a more gradual occupancy of D2-receptors differentiate risperidone from the other compounds. Both properties probably assist in preventing an extensive blockade of D2-receptors, the cause for extrapyramidal symptoms (EPS). The predominant 5-HT2A-receptor occupancy most likely underlies risperidone's beneficial effects on the negative symptoms of schizophrenia and an adequately low D2-receptor occupancy adds to the treatment of positive symptoms with a low liability of EPS.
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PMID:In vitro receptor binding and in vivo receptor occupancy in rat and guinea pig brain: risperidone compared with antipsychotics hitherto used. 878 44

Approximately 20-30% of patients with schizophrenia are resistant to conventional neuroleptics (i.e. are treatment-resistant). Clozapine has been shown to be effective in a proportion of treatment-resistant cases and to have a low side effect profile. However, it can cause agranulocytosis, is sedative and has marked anticholinergic properties. Risperidone, which is effective in chronic schizophrenia and has a low side effect profile and does not require routine blood monitoring, was compared with clozapine in a double-blind comparative study in 86 treatment-resistant patients. Preliminary findings indicate that, at endpoint, risperidone and clozapine were almost equieffective (total PANSS, PANSS subscales and CGI). Both drugs caused few adverse effects, and the severity of extrapyramidal symptoms was no different in the two groups. It is concluded that risperidone could be another drug effective in treatment-resistant schizophrenia. Further, larger trials will be needed to confirm this.
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PMID:Treatment-resistant schizophrenia: clinical experience with new antipsychotics. 879 17

Despite the proven efficacy of antipsychotic medication in the treatment of schizophrenia, a substantial proportion of patients derive little if any benefit from traditional medications. Though alternative strategies (e.g., increasing dosage, switching antipsychotic, or adding adjunctive medication) are frequently employed, success rates are often disappointing. Clozapine has shown to be effective in some poor or partially responsive patients in three prospective, random assignment, double-blind trials. Risperidone has not yet been extensively studied in treatment-resistant patients, but may also be a useful alternative.
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PMID:Treatment-resistant schizophrenic patients. 882 48

Recent clinical experiences with risperidone including controlled trials, clinical observations, and reports of side effects are reviewed. The controlled trials indicate that risperidone is an effective anti-psychotic that may have advantages over conventional antipsychotics for treating both positive and negative symptoms of schizophrenia. A number of clinical reports indicate that risperidone is also effective for psychotic illnesses that result from other disorders. Risperidone has a relatively mild side effect profile when compared with conventional antipsychotics.
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PMID:Clinical experience with risperidone. 882 52

Risperidone, a new antipsychotic drug, was recently approved by the Food and Drug Administration (FDA) on the basis of its having comparable efficacy and less toxicity than haloperidol. In a preliminary study to evaluate the therapeutic efficiency of this drug, we conducted a survey of resperidone utilization, cost, and safety during its first year of availability at an academic psychiatric hospital. Data were obtained from a computerized, centralized medical record system, from an adverse drug reaction monitoring system, and from pharmacy purchasing records. In its first year of availability, risperidone became the second most widely used antipsychotic agent at our institution. Most of this use extended beyond the adult schizophrenia population, for whom pre-marketing safety and efficacy data are available. The direct institutional cost of risperidone treatment exceeded the entire budget for antipsychotic drugs during the year before its release. Results from the adverse drug reaction reporting system did not indicate a strong advantage of risperidone over more established antipsychotic agents with respect to extrapyramidal side effects. Furthermore, the mean dose of risperidone associated with extrapyramidal symptoms was 3.5 mg/day, considerably lower than that suggested by pre-marketing studies in a more select patient group. These results confirm that new pharmacological agents are generally used in much broader patient populations than those for which efficacy and safety have been established prior to FDA approval. This study also raises questions about the therapeutic efficiency of risperidone compared with other antipsychotic drugs. We conclude that systematic studies of outcome, safety, and cost of new pharmaceuticals in naturalistic settings are needed to provide the data necessary to establish local standards of cost-effective care.
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PMID:Risperidone use in a teaching hospital during its first year after market approval: economic and clinical implications. 885 45

The antipsychotic drug risperidone shows high affinity for both central serotonin (5-HT)2A and dopamine (DA)-D2 receptors in vivo. By employing microdialysis in freely moving rats, the effects of acute risperidone administration on regional brain DA and 5-HT release and metabolism were compared with the corresponding effects of the atypical antipsychotic drug clozapine as well as amperozide, the selective DA-D2 receptor antagonist raclopride and the selective 5-HT2A/5-HT2C receptor antagonist ritanserin. Risperidone (0.2 or 2.0 mg/kg, SC) was found to increase DA release and metabolism to about the same extent in three major projection areas of the mesotelencephalic dopaminergic system, i.e. the nucleus accumbens (NAC), the medial prefrontal cortex (MPC) and the lateral striatum (STR). In contrast, clozapine and amperozide (both 10.0 mg/kg, SC), as well as raclopride (2.0 mg/kg, SC), were all found differentially to affect DA release and metabolism in the three projections areas. Specifically, clozapine and amperozide enhanced DA release in the MPC to a greater extent than in the NAC or the STR, whereas raclopride instead preferentially increased DA release in the NAC and the STR but not in the MPC. Ritanserin (3.0 mg/kg, SC) did not exert any major effects on DA metabolism in the three areas studied. In contrast to the regionally rather homogenous activation of brain DA systems caused by risperidone, the drug was found to enhance brain 5-HT metabolism preferentially in the MPC, as indicated by the elevated extracellular concentration of 5-hydroxyindoleacetic acid (5-HIAA) in this region. A similar elevation of the 5-HIAA level in the MPC was observed after amperozide and, to some extent, after clozapine and ritanserin administration. The risperidone-induced (2.0 mg/kg, SC) elevation of 5-HIAA concentrations in the frontal cortex was found to be paralleled by an increased 5-HT release in this brain area. Consequently, our findings demonstrate a pharmacological profile of risperidone, as reflected in brain DA metabolism, in between that of clozapine and the DA-D2 antagonists. The preferential activation of 5-HT release and metabolism in frontal cortical areas might be of particular relevance for the ameliorating effect of risperidone on negative symptoms in schizophrenia, especially when associated with depression.
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PMID:Risperidone: regional effects in vivo on release and metabolism of dopamine and serotonin in the rat brain. 893 2


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