The efficacy of the D2 and 5-HT2 antagonist risperidone (R 64,766) in the treatment of chronic psychosis. An open dose-finding study

Newer Formulations of Risperidone: Role in the Management of Psychotic Disorders

Antipsychotic long-acting injections improve relapse prevention in psychotic disorders. Three new risperidone formulations have been developed that offer advantages over currently available risperidone-based long-acting injections. Risperidone ISM^® is a monthly intramuscular injection that does not require loading doses or concurrent oral risperidone. RBP-7000 is a monthly subcutaneous injection not requiring loading or oral supplementation. BB0817 is a 6-monthly implant of risperidone injected subcutaneously. All three preparations have been shown to be effective and well tolerated in clinical trials. A fourth formulation (TV-46000), which can be given subcutaneously every 1 or 2 months, has recently begun trials.

Current and potential pharmacological and psychosocial interventions for anxiety symptoms and disorders in patients with schizophrenia: structured review

OBJECTIVE

Between 30% and 62% of patients with schizophrenia present with co-morbid anxiety disorders that are associated with increased overall burden. Our aim was to summarize current and potential interventions for anxiety in schizophrenia.

DESIGN

Structured review, summarizing pharmacological and psychosocial interventions used to reduce anxiety in schizophrenia and psychosis.

RESULTS

Antipsychotics have been shown to reduce anxiety, increase anxiety, or have no effect. These may be augmented with another antipsychotic, anxiolytic, or antidepressant. Novel agents, such as L-theanine, pregabalin, and cycloserine, show promise in attenuating anxiety in schizophrenia. Psychosocial therapies have been developed to reduce the distress of schizophrenia. Cognitive behavioural therapy (CBT) has shown that benefit and refinements in the therapy have been successful, for example, for managing worry in schizophrenia. CBT usually involves more than 16 sessions, as short courses of CBT do not attenuate the presentation of anxiety in schizophrenia. To address time and cost, the development of manualized CBT to address anxiety in schizophrenia is being developed.

CONCLUSIONS

The presence of coexisting anxiety symptoms and co-morbid anxiety disorders should be ascertained when assessing patients with schizophrenia or other psychoses as a range of pharmacological and psychosocial treatments are available.

Risperidone therapy in the control of behavioural disturbances in patients with learning disability

Objective: The objective of this audit to examine the effect of risperidone therapy in controlling some behavioural disturbances in people with learning disability.

Method: Retrospective analysis of various behavioural disturbances before and after beginning risperidone therapy (during the month before risperidone was started in each case, and during September 1994 in all cases).

Results: Risperidone was found to be effective in controlling various behaviour problems in 12 of 17 patients.

Conclusion: Risperidone may selectively influence behaviour problems secondary to possible underlying mental illness but not others. There was also some evidence that it was more effective in an average dose of 6-8mg/day, but was not beneficial in doses smaller or larger than this dose range.

Comparative evaluation of forced swim test and tail suspension test as models of negative symptom of schizophrenia in rodents

Previous studies have shown that the administration of NMDA antagonist can induce negative symptoms of schizophrenia which can be tested through the enhanced immobility observed in the forced swim test (FST). In the present study, we have compared the effects of acute as well as chronic administration of a noncompetitive NMDA receptor antagonist, ketamine on FST, and another behaviour despair model, tail suspension test (TST). Our observations suggest that chronic ketamine administration induced a state of enhanced immobility in FST, but such findings were not replicated in the TST model. Further, in FST, treatment with clozapine reverses the ketamine-induced immobility in mice, whereas it enhances the immobility duration in the TST model. However, haloperidol showed no protective effects in both models. The data suggests that although both of these tests show common behavioural measure of feeling despair, however, the underlying pathophysiology seems to be different. Hence, forced swim test but not tail suspension test can be used as a model of negative symptom of psychosis in mice.

The relationship between the daily dose, the plasma concentration of blonanserin, and its plasma anti-dopamine D2 and anti-serotonin 5-HT2A activity

OBJECTIVE

Blonanserin (BNS) possesses anti-serotonin 5-HT(2A) activity in addition to anti-dopamine D(2) activity, which is characteristic of second-generation antipsychotics, little information is available on its pharmacologic profile in vivo. We investigated the BNS daily dose, plasma concentration, plasma anti-D(2) activity, and plasma anti-5-HT(2A) activity in schizophrenia in a total of 14 subjects.

METHODS

Blood samples were taken 14 days after the BNS dose was fixed, and the plasma concentration was measured by means of high-performance liquid chromatographic (HPLC) method. In addition, the plasma anti-D(2) activity and anti-5-HT(2A) activity were measured by means of radioreceptor assays in which [(3)H]-spiperone and [(3)H]-ketanserin were used.

RESULTS

The results revealed a statistically significant correlation between the daily dose and the plasma concentration (p = 0.04). Statistically significant correlations were also observed between the plasma concentration and the anti-D(2) activity and between the plasma concentration and the anti-5-HT(2A) activity (p = 0.003 and 0.04).

CONCLUSIONS

It is therefore believed that both the anti-D(2) activity in plasma and the anti-5-HT(2A) activity in plasma are regulated almost solely by the unchanged principal. Moreover, the mean plasma serotonin/dopamine (S/D) ratio was 0.9 and BNS exhibited both anti-D(2) activity and also anti-5-HT(2A) activity in vivo, as well, so it was clear that the in vitro pharmacological profile was retained in vivo.

Efficacy and safety of brand-risperidone versus similar-risperidone in elderly patients with neuropsychiatric disorders: A retrospective study

To compare the efficacy and tolerability of brand-risperidone against similar-risperidone in elderly outpatients.

Fluctuating plasma levels of the active moiety of risperidone is related to occurrence of extrapyramidal symptoms

In the present study, we compared the plasma levels of the active moiety (i.e. risperidone plus 9-hydroxyrisperidone) in a steady state in 54 Japanese schizophrenic patients with or without emerging extrapyramidal symptoms (EPS and non-EPS groups, respectively) who were treated with 4 mg/day risperidone. No differences were observed in the plasma levels of the active moiety at 4 and 8 weeks after risperiodne administration in both groups. However, the EPS group patients showed a greater number of fluctuations/larger fluctuations in the plasma active moiety levels than those in the non-EPS group. These results suggest that a stable plasma active moiety level maybe important for preventing EPSs during treatment with risperidone.

Pharmacological treatment of primary negative symptoms in schizophrenia: a systematic review

BACKGROUND

Optimal treatment of primary negative symptoms is important because their presence is associated with poor outcome.

AIMS

To systematically review all studies dealing with the efficacy of pharmacological agents on primary negative symptoms.

METHOD

A comprehensive search of the relevant literature was undertaken using electronic database, reference lists and personal contact.

RESULTS

There is a lack of standardized research designs. Amisulpride is the most extensively studied drug with respect to efficacy against primary negative symptoms. At low doses it demonstrates a consistent, modest effect compared to placebo, though not to conventional antipsychotics and has yet to be tested against other atypicals. Evidence from multiple studies that used simple statistical analyses and inclusion criteria for patients with primary negative symptoms does not support a direct effect for clozapine. Path-analysis studies support the direct effects of risperidone, olanzapine, sertindole and aripiprazole, however, different statistical analyses of the same risperidone study produced conflicting results and the direct effects of olanzapine were not confirmed in selected patients with primary negative symptoms. There are no studies supporting the use of ziprasidone or quetiapine. The effects of typical antipsychotics on primary negative symptoms are inconclusive and likely to depend on drug dosages. Selective serotonin reuptake inhibitors (SSRIs), mirtazepine and NMDA agonists show early promise but require further study. Novel agents such as selegiline, naltrexone, dehydroepiandrosterone, galantamine, Ginkgo, nitric oxide, L-deprenyl and pergolide show positive effects on general negative symptoms but remain untested against primary negative symptoms.

CONCLUSIONS

Further studies using standardized selective inclusion criteria and controlling for chronicity are needed. Research guidelines are discussed.

An open study of risperidone liquid in the acute phase of schizophrenia

An open-label study was performed to investigate the clinical efficacy and mechanisms of risperidone liquid in ameliorating positive symptoms in the acute phase of schizophrenia. Eighty-eight patients (M/F: 50/38; age: 18-74 years;, mean +/- SD =32 +/- 16 years) meeting DSM-IV criteria for schizophrenia and treated with risperidone liquid (14 patients also used lorazepam) were evaluated with regard to their clinical improvement and extrapyramidal side effects using the positive and negative syndrome scale (PANSS) and the Simpson and Angus scale (SAS), while plasma concentrations of HVA and MHPG were analysed by HPLC-ECD before and 4 weeks after risperidone liquid administration. Patients showing a 50% or greater improvement in PANSS scores were defined as responders. An improvement in the PANSS scores related to excitement, hostility and poor impulse control was seen within 7 days after administration of risperidone liquid, and an improvement with regard to hallucinatory behaviour and uncooperativeness was seen within 14 days after its administration. Finally, 68% of patients were classified as responders 4 weeks after risperidone liquid administration. The scores of SAS were not changed after risperidone liquid administration. Pretreatment plasma homovanillic acid (HVA) levels in the responders (8.1 +/- 2.9 ng/ml) were higher than those in nonresponders (5.9 +/- 1.9 ng/ml). In addition, a negative correlation was seen between the changes in plasma HVA levels and the percentage of improvement in PANSS scores. On the other hand, there were no differences between pretreatment plasma 3-methoxy-4-hydroxyphenylglycol (MHPG) levels and those of nonresponders. These results suggest that risperidone liquid is effective and well tolerated for the treatment of acute phase schizophrenic patients, and that efficacy is related to its affects on dopaminergic activity, not noradrenergic activity.

Prediction of response to risperidone treatment with respect to plasma concencentrations of risperidone, catecholamine metabolites, and polymorphism of cytochrome P450 2D6

In the present study, we examined the relationships between plasma concentrations of risperidone and clinical responses, extrapyramidal symptoms, plasma levels of cotinine and caffeine, or cytochrome (cyp)2D6 genotypes. In addition, we also investigated the relationships between plasma levels of 3-methoxy-4-hydroxyphenylglycol (MHPG) or homovanillic (HVA) acid and clinical responses to risperidone. One hundred and 36 patients (male/female: 58/78, age 37+/-13 years) who met DSM-IV criteria for schizophrenia, schizoaffective disorder, delusional disorder and brief psychotic disorder, and who were being treated with risperidone alone, were evaluated regarding their clinical improvement and extrapyramidal symptoms using the Positive and Negative Syndrome Scale (PANSS) and Simpson and Angus (SAS), respectively, and plasma levels of cotinine, caffeine, MHPG and HVA were analysed by high-performance liquid chromatography. The cyp2D6*5 and *10 alleles were identified using the polymerase chain reaction. There was a positive correlation between plasma levels of risperidone plus 9-hydroxyrisperidone (active moiety) and SAS scores, but not the PANSS. Pretreatment HVA levels in responders were higher than those in nonresponders. In addition, there was a negative correlation between changes in HVA levels and improvement in PANSS scores. There was no association between plasma levels of risperidone and plasma levels of cotinine or caffeine. Furthermore, there were no differences in the risperidone/9-hydroxyrisperidone ratio, clinical improvements and extrapyramidal symptoms among cyp2D6 genotypes. These results indicate that pretreatment HVA levels and plasma concentrations of active moiety might play a part in predicting the clinical response and occurrence of extrapyramidal symptoms, respectively, when treating patients with risperidone.

Plasma levels of homovanillic acid and the response to risperidone in first episode untreated acute schizophrenia

We have previously reported that risperidone might improve negative symptoms in schizophrenia by influencing noradrenergic neurons. In the present study, we focused on the clinical efficacy and mechanisms of risperidone towards positive symptoms in the acute phase of schizophrenia. Thirty-four patients meeting DSM-IV criteria for schizophrenia and treated with risperidone alone were evaluated regarding their clinical improvement using the Positive and Negative Syndrome Scale (PANSS) before and 2 weeks after risperidone administration, and blood samples were also drawn at the same times. Plasma concentrations of homovanillic acid (HVA) and 3-methoxy-4-hydroxyphenylglycol were analysed by high-performance liquid chromatography with electrochemical detection. Plasma HVA levels in the responders to the risperidone treatment (more than 50% improvement in scores of positive symptoms in PANSS) were higher than those of non-responders before risperidone administration. Furthermore, there was a negative trend between changes in plasma HVA levels and improvement of total scores for positive symptoms in PANSS. These results suggest that higher levels of plasma HVA before risperidone administration might be a predictor of a good response to risperidone treatment, and the influence of risperidone on dopaminergic activity might be associated with its efficacy in treating symptoms of schizophrenia in the acute phase.

Effect of AD-5423 on animal models of schizophrenia: phencyclidine-induced behavioral changes in mice

The antipsychotic efficacy of AD-5423, which has the properties of both a serotonin 5-HT(2) and a dopamine D(2) receptor antagonist, was evaluated using animal models of schizophrenia. Sensitization to phencyclidine (PCP)-induced hyperlocomotion is considered a model of the positive symptoms of schizophrenia, and was significantly antagonized by AD-5423 and haloperidol. The PCP-induced enhancement of immobility induced by the forced swimming test, a model of the negative symptoms of schizophrenia, was attenuated by AD-5423 but not by haloperidol. Since this attenuated effect of AD-5423 was antagonized by DOI, a serotonin 5-HT(2) receptor agonist, it is postulated to be mediated by serotonin 5-HT(2) receptors. These findings suggest that AD-5423 would be clinically effective against both the positive and negative symptoms of schizophrenia.

Possible relationship between combined plasma concentrations of risperidone plus 9-hydroxyrisperidone and extrapyramidal symptoms. Preliminary study

We investigated the relationships between extrapyramidal symptoms (EPS) induced by risperidone, the dosage of risperidone and the combined plasma concentrations of risperidone plus its active metabolite, 9-hydroxyrisperidone, in 20 schizophrenic patients. There was a positive correlation between the scores on the Simpson and Angus Scale and both the dosage of risperidone and the sum of the plasma levels of risperidone and 9-hydroxyrisperidone. These results suggest that EPS induced by risperidone increase in conjunction with both the dosage of risperidone and the total plasma concentrations of the parent compound and its active metabolite.

Risperidone versus haloperidol in the treatment of acute exacerbations of chronic inpatients with schizophrenia: a randomized double-blind study

The purpose of this study was to compare the efficacy and safety of risperidone and haloperidol in treatment-resistant chronic schizophrenic patients. Subjects (n = 78) who met DSM-III criteria for schizophrenia were randomly assigned to receive 6 mg/day of risperidone or 20 mg/day of haloperidol for 12 weeks. Clinical efficacy was determined using the Positive and Negative Syndrome Scale (PANSS), and side-effects with the Treatment Emergent Symptom Scale (TESS). Risperidone produced a mean 39.8 +/- 24.1% reduction in total PANSS score compared to a mean 28.3 + 19.4% reduction in the haloperidol group (P < 0.05). Analysis of changes for the three subscores of the PANSS revealed that the general psychopathology and negative subscores were significantly improved in the risperidone group compared to the haloperidol group. As for the side-effects, the risperidone group showed a significantly lower TESS total score, as well as nervous system symptoms subscore and cardiovascular symptoms subscore, compared to the haloperidol group. Risperidone appears to be a more effective and better tolerated antipsychotic drug in treatment-refractory Chinese schizophrenia than haloperidol.

Neuropharmacological profiles of a novel atypical antipsychotic, NRA0562, in rats

Neuropharmacological profiles of 5-(2-[4-(6-fluoro-1H-indole-3-yl) piperidine-1-yl] ethyl)-4-(4-fluorophenyl) thiazole-2-carboxylic acid amide (NRA0562) in rats were examined using electrophysiological and immunohistochemical methods. The firing rates of the substantia nigra pars compacta (A9) and the ventral tegmental area (A10) dopamine neurons were inhibited by methamphetamine (1 mg/kg, i.v.). NRA0562 dose-dependently reversed the inhibitory effects of methamphetamine on A9 and on A10 dopamine neurons. NRA0562 was more potent to reverse the inhibitory effects of methamphetamine on A10 (ED(50)=0.3 mg/kg) than on A9 (ED(50)=0.9 mg/kg) dopamine neurons. NRA0562 produced significant increases in Fos-like immunoreactivity in both the nucleus accumbens and the dorsolateral striatum. The difference between the number of Fos-like immunoreactivity produced by NRA0562 in the nucleus accumbens vs. dorsolateral striatum, referred to as the atypical index, was positive. Similar results could be observed with risperidone, an atypical antipsychotic. These results suggest that NRA0562 may have the atypical antipsychotic activities seen with risperidone, but without the liability of motor side effects typical of classical antipsychotics.

Refractory schizophrenia and atypical antipsychotics

Treatment resistant or refractory schizophrenia is a difficult to define condition of largely unknown prevalence. For 10 years, clozapine has been the standard treatment in this condition and is recognized unequivocally as being effective. However, clozapine is sometimes poorly tolerated and has the potential for severe toxicity. Partly as a result of this, other atypicals have recently been evaluated as treatments for refractory schizophrenia. In order to evaluate the evidence base relating to the drug treatment of refractory schizophrenia, we developed a refractoriness rating based on previous work. Using this rating, we assessed all trials of atypicals in schizophrenia unresponsive to at least one drug. Overall, clozapine was consistently shown to be effective in refractory schizophrenia, even when stringently defined. Data relating to olanzapine and risperidone are equivocal at best, and there is some evidence to suggest that they are less effective than clozapine. There is essentially no cogent evidence to support the use of any other atypical in refractory schizophrenia. Clozapine remains the drug of choice in this condition.

Pharmacology and clinical experience with risperidone

Risperidone (Risperdal, Janssen Pharmaceutica) is a second generation antipsychotic (SGA) for the treatment of schizophrenia and other psychotic disorders. It is a potent antagonist of serotonin-2 (5-HT2) and dopamine-2 (D2) receptors in the brain. In comparison to conventional antipsychotics, risperidone demonstrates superior efficacy against the positive and negative symptoms of schizophrenia and a decreased occurrence of extrapyramidal side effects (EPS). Risperidone causes less weight gain than other marketed SGAs, but can increase prolactin levels and cause EPS in a dose-related manner. In a variety of pharmacoeconomic analyses, it has proven to be a cost-effective addition to the antipsychotic armamentarium. As the first SGA available for front line use, risperidone has established a new standard of care for the treatment of individuals with psychotic disorders.

Risperidone in the treatment of dopamine-induced psychosis in Parkinson's disease: an open pilot trial

PURPOSE

To evaluate the safety and efficacy of risperidone in patients with Parkinson's disease (PD) who are experiencing significant dopamine-induced psychosis.

PATIENTS AND METHODS

Seventeen patients (median age, 72 yrs) participated in this 12-week, open pilot study receiving 0.5 to 3 mg oral risperidone per day. Maintenance antiparkinsonian medication was continued throughout, although psychotropic medication was discontinued. EFFICACY RESULTS: Risperidone produced a substantial improvement in psychotic symptoms, shown on the mean total positive subscale score on the Positive and Negative Syndrome Scale (PANSS) by a 30% improvement (-3.1 decrease) after 1 week and a 66% improvement (-6.8 decrease) at end point. This improvement was most evident in the items delusions, hallucinatory behavior, and suspiciousness/persecution. Risperidone also achieved significant improvement from baseline in Clinical Global Impression (CGI)-severity and CGI-improvement (p < 0.001, Page test). Risperidone treatment did not adversely affect symptoms specific to Parkinson's disease, as assessed by the Unified Parkinson's Disease Rating Scale (UPDRS). SAFETY RESULTS: Sixteen patients reported at least one adverse event, but only two patients withdrew as a result of adverse events. No significant changes or clinically relevant abnormalities were observed in laboratory parameters or vital signs.

CONCLUSION

Short-term use of risperidone (mean dosage, 1.1 mg per day) improves the psychopathology of patients with PD who have dopamine-induced psychosis without adversely affecting the symptoms of PD. Higher doses and long-term use were not addressed in this study and may be precluded by extrapyramidal side effects.

Risperidone in treatment-refractory schizophrenia

OBJECTIVE

The purpose of this study was to evaluate the clinical safety and efficacy of risperidone compared to haloperidol in patients with treatment-refractory schizophrenia.

METHOD

Sixty-seven medication-unresponsive subjects were randomly assigned to treatment with risperidone (N = 34) or haloperidol (N = 33). After a 3-7 day-placebo washout period, there was a 4-week, double-blind, fixed-dose comparison trial that was followed by a 4-week, flexible-dose phase. Measures of clinical change were quantified by standard psychopathologic and neuromotor instruments.

RESULTS

Risperidone demonstrated clinical efficacy superior to that of haloperidol on the total Brief Psychiatric Rating Scale (BPRS) after the first 4 weeks of treatment. Risperidone did not show any advantage over haloperidol after an additional 4 weeks. Overall improvement on the BPRS at 4 weeks was significantly better for the risperidone group (24%) than for the haloperidol group (11%). Risperidone-treated subjects were significantly less likely than haloperidol-treated subjects to require concomitant anticholinergic medication after 4 weeks (20% versus 63%); they also had significantly les observable akathisia (24% versus 53%) and significantly less severe tardive dyskinesia. Baseline characteristics that correlated significantly with risperidone response were positive symptoms, conceptual disorganization, akathisia, and tardive dyskinesia.

CONCLUSIONS

Risperidone was better tolerated and more effective in a subset of patients with treatment-refractory schizophrenia. Positive psychotic symptoms and extrapyramidal side effects at baseline appear to be powerful predictors of subsequent response to risperidone.

5-HT2A receptor antagonists block MK-801-induced stereotypy and hyperlocomotion

The present study was undertaken to examine the effect of 5-HT2A receptor antagonists on MK-801 (5-methyl-10,11-dihydro-5H-dibenzo (a,d) cyclohepten-5,10-imine)-induced stereotypy and hyperlocomotion. MK-801 (0.1, 0.25 and 0.5 mg/kg) dose-dependently increased stereotypy and locomotion in mice. The 5-HT2A receptor antagonists, ketanserin (2.5, 5 and 10 mg/kg) and ritanserin (0.5, 1 and 2 mg/kg), dose-dependently blocked MK-801 (0.5 mg/kg)-induced hyperlocomotion. Only the higher dose (2 mg/kg) of seganserin could block locomotor activity. Similarly, ketanserin (2.5, 5 and 10 mg/kg), ritanserin (1 and 2 mg/kg) and seganserin (0.5, 1 and 2 mg/kg) dose-dependently blocked MK-801 (0.5 mg/kg)-induced stereotypy. The results suggest the involvement of 5-HT2A receptors in MK-801-induced stereotypy and hyperlocomotion. The lack of effect on spontaneous locomotion further suggests that 5-HT2A receptor antagonists will be less prone to induce psychomotor side-effects.

Emerging roles for novel antipsychotic medications in the treatment of schizophrenia

Antipsychotic medications are the mainstay of treatment for schizophrenia. The recent advent of atypical antipsychotics has provided new clinical options and set higher expectations for the treatment of schizophrenia. It is not yet clear how each different drug will fit within the therapeutic armamentarium and this lack is most evident with considering patients with treatment refractory schizophrenia. On the other hand, the expectation of superior efficacy, more benign side effect profile and potential to impact the longitudinal course of schizophrenia provide a rationale for the use of novel antipsychotics as a first-line treatment of schizophrenia.

Extrapyramidal side effects with risperidone and haloperidol at comparable D2 receptor occupancy levels

Risperidone is an antipsychotic drug with high affinity at dopamine D2 and serotonin 5-HT2 receptors. Previous clinical studies have proposed that risperidone's pharmacologic profile may produce improved efficacy for negative psychotic symptoms and decreased propensity for extrapyramidal side effects; features shared by so-called 'atypical' neuroleptics. To determine if routine risperidone treatment is associated with a unique degree of D2 receptor occupancy and pattern of clinical effects, we used [123I]IBZM SPECT to determine D2 occupancy in subjects treated with routine clinical doses of risperidone (n = 12) or haloperidol (n = 7). Both risperidone and haloperidol produced D2 occupancy levels between approximately 60 and 90% at standard clinical doses. There was no significant difference between occupancy levels obtained with haloperidol or risperidone. Drug-induced parkinsonism was observed in subjects treated with risperidone (42%) and haloperidol (29%) and was observed at occupancy levels above 60%. Based on these observations, it is concluded that 5-HT2 blockade obtained with risperidone at D2 occupancy rates of 60% and above does not appear to protect against the risk for extrapyramidal side effects.

Determination of a novel anti-psychotic agent AD-5423 and its metabolites in plasma by high-performance liquid chromatography with fluorescence detection

AD-5423, 2-(4-ethyl-1-piperazinyl)-4-(4-fluorophenyl)-5,6,7,8,9,10-hexahydrocy cloocta [b]pyridine, is a novel anti-psychotic agent. In order to investigate the pharmacokinetics of AD-5423, a simple and sensitive high-performance liquid chromatographic (HPLC) method has been developed for the simultaneous determination of AD-5423 and its two N-oxidized metabolites (N-desethyl AD-5423 and AD-5423 N-oxide) in plasma. After pretreatment of a plasma sample by solid-phase extraction, AD-5423 and its metabolites were analyzed on a HPLC with fluorescence detection (335/410 nm). Chromatography was performed on two C18 reversed-phase columns connected by a switching system, with a mobile phase of acetonitrile-methanol-25 mM sodium phosphate buffer (pH 2.5) containing 25 mM sodium 1-heptanesulfonate (36:26:38 v/v/v). The method gives satisfactory accuracy and precision for the determination of AD-5423 and its metabolites. In human plasma, accurate determination are possible over the concentration ranges of 0.04-5 ng ml-1 for AD-5423 and 0.1-5 ng ml-1 for N-oxidized metabolites. The intra- and inter-day assay precision (R.S.D.) of AD-5423 (0.5 ng ml-1) were 3.6 and 7.2%, respectively. In plasma of experimental animals, the validated quantitative range are 0.1-100 ng ml-1 for both AD-5423 and its metabolites.

Effects of risperidone, clozapine and haloperidol on extracellular recordings of substantia nigra reticulata neurons of the rat brain

Risperidone has proven to be effective as an antipsychotic drug and has fewer extrapyramidal side-effects than classic neuroleptics. In addition to its dopamine D2 receptor antagonistic properties, this antipsychotic agent is a potent 5-HT2 receptor antagonist. The atypical antipsychotic, clozapine, also possesses both dopamine D2 and 5-HT2 receptor affinity next to affinities for other receptors. To gain an insight in the consequences for basal ganglia activity of treatment with these atypical neuroleptics vs. typical neuroleptics, the effects of cumulative doses of risperidone, clozapine and haloperidol on the firing rate of substantia nigra reticulata neurons were studied. Extracellular recordings were performed in chloralhydrate-anaesthetized male Wistar rats. Both risperidone (50-3200 micrograms/kg i.v.) and clozapine (100-6400 micrograms/kg i.v.) dose dependently decreased substantia nigra reticulata activity maximally to 70% of the basal activity. With both treatments, a dose of 800 micrograms/kg was significantly effective. In contrast, haloperidol (12.5-800 micrograms/kg i.v.) gradually induced a slight increase in substantia nigra reticulata activity, which was identical to the substantia nigra reticulata activity after saline treatment. Therefore, these results indicate that typical and atypical neuroleptics affect differentially the output of the basal ganglia in the substantia nigra reticulata. To evaluate the involvement of 5-HT2 receptors in the effect of risperidone, the 5-HT2 receptor agonist, quipazine (0.5 mg/kg i.p.), was administered 15 min preceding risperidone treatment. A 4-fold higher dose of risperidone was needed to significantly affect the substantia nigra reticulata firing rate. Thus, the 5-HT2 component of the effect of risperidone is, at least partly, responsible for the difference in effect on substantia nigra reticulata neurons in comparison to haloperidol.

Risperidone in the treatment of schizophrenia: results of a study of patients from Germany, Austria, and Switzerland

Results of a subanalysis of data from the multinational risperidone trial (RIS-INT-2) are reported. Patients with chronic schizophrenia were treated with risperidone at 1 mg/day (n = 25), 4 mg/day (n = 27), 8 mg/day (n = 29), 12 mg/day (n = 31), or 16 mg/day (n = 29), or 10 mg/day of haloperidol for 8 weeks. According to the Positive and Negative Syndrome Scale (PANSS) total and subscale scores, improvements were noted in each treatment group from baseline to treatment endpoint. On each scale the magnitude of improvement was greater in the risperidone patients than in the haloperidol patients. The onset of action of risperidone was faster than haloperidol. By treatment week 2, over half of the patients receiving > or = 4 mg/day of risperidone were clinically improved (> or = 20% reduction in total PANSS scores). This rate of improvement was not seen until week 6 in the haloperidol patients. Severity of extrapyramidal symptoms (scores on the Extrapyramidal Symptom Scale) was significantly lower in patients receiving 1 or 4 mg/day of risperidone than in patients receiving higher risperidone doses and in haloperidol patients. The optimal dose of risperidone, in terms of both efficacy and safety, was 4 mg/day. These results confirm the findings of the controlled trials of risperidone conducted in North America and the multinational trial.

Risperidone in Elderly Schizophrenic Patients: An Open-Label Trial

The authors assessed the safety and efficacy of risperidone in a group of elderly patients with chronic schizophrenia and behavioral disturbances (N = 10). There were no clinically significant changes on physical examination. Also, schizophrenic symptoms and cognitive performance improved during risperidone administration. Patients showed a sufficient improvement in both areas to warrant a larger, double-blind study assessing the effects of risperidone on cognitive and psychiatric symptoms in elderly psychotic patients.

Behavioural interactions between 5-hydroxytryptophan, neuroleptic agents and 5-HT receptor antagonists in modifying rodent responding to aversive situations

1. The ability of 5-hydroxytryptophan, 5-HT2 receptor antagonists and typical and atypical neuroleptic agents to modify behavioural responding to aversive situations was investigated in the mouse light/dark test and rat social interaction. 2. The administration of 5-hydroxytryptophan inhibited rat social interaction and the exploratory behaviour of mice in the light/dark test. 3. The 5-HT2 receptor antagonists, ketanserin, ritanserin, MDL11939, methysergide and RP62203, the neuroleptic agents, spiperone, haloperidol and benperidol, and the atypical neuroleptic agent, clozapine, when administered alone failed to modify mouse or rat behaviour. In contrast, when administered alone, sulpiride in rats and mice and thioridazine in rats disinhibited behaviour. 4. Methysergide, RP62203, ketanserin, ritanserin and MDL11939 antagonized the inhibitory effects of 5-hydroxytryptophan or reversed the inhibitory effects to one of disinhibition. 5. Low doses of spiperone (but not haloperidol or benperidol) also antagonized the inhibitory effects of 5-hydroxytryptophan in the rat but not the mouse. Higher doses of the three neuroleptic agents caused locomotor depression in both rats and mice which obscured any specific changes in behavioural responding to the aversive situations. 6. The disinhibitory profile of sulpiride in both mice and rats and thioridazine in rats was evident during their interaction with 5-hydroxytryptophan. Thioridazine in the mouse and clozapine in rats and mice also reversed the inhibitory effects of 5-hydroxytryptophan to one of disinhibition. 7. In summary, we present evidence that the atypical neuroleptic agents, thioridazine and clozapine, with their known affinity for the 5-HT2 receptors, can mimic the actions of reference 5-HT2 receptor antagonists to antagonize the inhibitory effects of 5-hydroxytryptophan in rodent models of anxiety. The results are intepreted in terms of drug action on different 5-HT2 and other 5-HT receptor subtypes. In addition, thioridazine and sulpiride have disinhibitory effects in their own right which remain to be explained.

Enhancement of immobility in a forced swimming test by subacute or repeated treatment with phencyclidine: a new model of schizophrenia

1. Immobility induced by forced swimming is well known as an animal model of depression. To develop an animal model for the negative symptoms of schizophrenia, in particular the depressive symptoms, the effect of phencyclidine (PCP) on immobility in the forced swimming test was investigated in mice, since PCP produces such negative symptoms in humans. 2. Repeated treatment with PCP (10 mg kg-1 day-1, s.c., once a day for 14 days) prolonged the immobility time in the forced swimming test 24 h after the final injection compared with saline treatment; the effect was not obtained by single or 5 treatments with PCP (10 mg kg-1, s.c.), or by repeated treatment with methamphetamine (0.5 and 1 mg kg-1 day-1, s.c., once a day for 14 days). 3. The enhancing effect of PCP (10 mg kg-1 day-1, s.c.) on the immobility persisted for at least 21 days after the withdrawal of the drug. 4. Haloperidol (0.3 and 1 mg kg-1, p.o.), ritanserin (3 and 10 mg kg-1, p.o.), risperidone (0.1-1 mg kg-1, p.o.), and clozapine (3 and 10 mg kg-1, p.o.) failed to attenuate the immobility induced by the forced swimming in mice repeatedly treated with saline when the drugs were administered 1 h before the forced swimming test. However, ritanserin (30 mg kg-1) and clozapine (30 mg kg-1) did attenuate this immobility. 5. The enhancing effect of PCP on the immobility was attenuated by ritanserin (3 and 10 mg kg-1, p.o.), risperidone (0.3 mg kg-1, p.o.), and clozapine (3 and 10 mg kg-1, p.o.), whereas haloperidol (0.3 and 1 mg kg-1, p.o.) had no effect. 6. These results suggest that the enhancement of immobility in the forced swimming test brought about by repeated PCP treatment could be used as a model of the negative symptoms, particularly the depression, of schizophrenia. This effect of PCP appeared to be mediated, at least in part, via 5-HT2A receptors.

Case study: risperidone in children and adolescents with schizophrenia

Schizophrenia in children is an uncommon disorder with devastating effects. Study of the efficacy of treatment with neuroleptics in children with schizophrenia is only now beginning, and there are limited studies on the effectiveness of novel neuroleptics on the positive and negative symptoms of schizophrenia in children. Four patients with schizophrenia, aged 12 to 17 years, were treated with risperidone (4 to 5 mg/day), a 5-HT2/D2 receptor blocking agent, to determine its effectiveness. Three patients had substantial improvement in their negative symptoms without side effects.

Risperidone in the treatment of psychosis; a concise review

Risperidone (Risperdal®) is a recently developed antipsychotic drug with the combination of serotonin-5HT2A-and dopamine-D2-antagonism (SDA). In patients with schizophrenia, risperidone reduces positive symptoms at least equally effective as haloperidol, however, risperidone has a reduced propensity for the induction of extrapyramidal symptoms. In addition, available evidence indicates that risperidone may be an effective treatment for negative symptoms. The optimum daily dose range is between 4 and 8 mgfor most patients. In this review article, risperidone is compared with some other (classical and atypical) neuroleptics. In addition, the pharmacological and pharmacokinetic properties of risperidone are reviewed.

Risperidone in the treatment of patients with chronic schizophrenia: a multi-national, multi-centre, double-blind, parallel-group study versus haloperidol. Risperidone Study Group

BACKGROUND

This study was performed in order to evaluate the short-term efficacy and safety of fixed risperidone doses compared to haloperidol.

METHOD

In a multi-national, parallel-group, double-blind study, patients with chronic schizophrenia (DSM-III-R) were randomly assigned to risperidone 1, 4, 8, 12 or 16 mg or haloperidol 10 mg daily for 8 weeks. Efficacy was assessed by the Positive and Negative Syndrome Scale for schizophrenia (PANSS) and clinical global impression (CGI), and safety primarily by the Extrapyramidal Symptom Rating Scale (ESRS).

RESULTS

One thousand three hundred and sixty-two patients were evaluated. The optimum risperidone doses were 4 mg and 8 mg, with response rates of 63.4% (56.8%; 69.7%) and 65.8% (59.2%; 71.9%) respectively. Response rate in haloperidol-treated patients was 58.7% (52.0%; 65.3%); the 95% confidence intervals (CI) of the differences between risperidone 4 mg or 8 mg and haloperidol were (- 4.3%; 13.7%) and (- 1.9%; 16.0%) respectively. There were no significant differences in CGI scores at endpoint between risperidone 4 mg, 8 mg, 12 mg and 16 mg and haloperidol (3.0, 3.0, 3.2, 3.1 and 3.1 respectively); the 95% CI of the differences between risperidone 4 mg or 8 mg and haloperidol were ( - 0.4; 0.1) and ( - 0.3; 0.2) respectively. Mean shifts to the maximum total ESRS scores versus baseline (mean (confidence interval)) were significantly greater in haloperidol-treated patients (5.1 (4.0; 6.2)) than in the risperidone 1, 4, 8 and 12 mg groups (1.1 (0.3; 1.9); 1.8 (0.9; 2.7); 2.7 (1.8; 3.6) and 3.2 (2.3; 4.1) respectively (P < 0.05)).

CONCLUSION

Risperidone is an effective antipsychotic for the treatment of chronic schizophrenia; doses of 4 and 8 mg seem to be optimal and have a lower incidence of side-effects than haloperidol.

Serotonin receptors: subtypes, functional responses and therapeutic relevance

Recent, rapid progress in the molecular biology of serotonin (5-HT) receptors requires conceptual re-thinking with respect to receptor classification. Thus, based on operational criteria (agonist and antagonist rank order), as well as transduction mechanisms involved and the structure of the receptor protein, the Nomenclature Committee of the Serotonin Club has proposed the following classification and nomenclature: the main receptor types 5-HT1 to 5-HT4, recombinant receptors (e.g. 5-ht5 to 5-ht7) and 'orphan' receptors. The aim of the present review is to discuss the events leading to this classification, the criteria for and functional responses mediated by various 5-HT receptors, as well as the therapeutic possibilities with 5-HT ligands.

Risperidone versus zuclopenthixol in the treatment of acute schizophrenic episodes: a double-blind parallel-group trial

A double-blind, randomized, multi-center, parallel-group study was conducted in Finland to compare the efficacy and safety of risperidone with zuclopenthixol in patients with acute exacerbations of schizophrenia or schizophreniform disorder. Ninety-eight patients were randomly assigned to treatment with risperidone (n = 48) or zuclopenthixol (n = 50), in variable doses, for 6 weeks. The mean daily doses of risperidone and zuclopenthixol at the end of the trial were 8 mg and 38 mg respectively. Efficacy was assessed throughout by the Positive and Negative Syndrome Scale for schizophrenia and Clinical Global Impression. Safety assessments included the Extrapyramidal Symptom Rating Scale, UKU Side-Effect Rating Scale, vital signs, body weight and laboratory screening. The results indicate that risperidone is at least as effective as zuclopenthixol for the treatment of acute schizophrenic episodes, with a trend towards greater improvement in the overall severity of symptoms. The onset of action was significantly shorter with risperidone than with zuclopenthixol. Although the general tolerability of the two drugs was comparable, fewer patients experienced extrapyramidal symptoms with risperidone, so that significantly fewer risperidone-treated patients required antiparkinsonian medication.

Recent advances in the pharmacotherapy of schizophrenia

The major advance in the psychopharmacology of schizophrenia has been the rediscovery of clozapine and the development of other novel antipsychotic drugs, all of which are superior to typical neuroleptic drugs with regard to extrapyramidal symptoms. Clozapine, the best studied of these agents, is also superior in efficacy with regard to psychopathology and cognitive function and has been shown not to cause tardive dyskinesia. A variety of other novel agents, e.g., risperidone, olanazpine, amperozide, seroquel, sertindole, zaprisidone and melperone, must be further studied to establish their efficacy relative to clozapine or the typical neuroleptics, or both. It is likely that these novel agents will displace the typical neuroleptic drugs as the primary treatment of schizophrenia.

Risperidone in the treatment of pervasive developmental disorder

Elevated concentrations of blood serotonin have been documented in autistic children and mentally retarded adults. Antiserotonergic pharmacotherapy has been partially effective in treating a subgroup of children with autistic disorder. Therefore, the possibility is raised that an antiserotonergic treatment may be of value to adult psychiatric patients with a history of pervasive developmental disorder. Two such cases are described where the patients underwent psychiatric and neuropsychological examination before and after treatment with risperidone, a potent 5-HT2 antagonist with additional D2 antagonistic properties. Particular improvements were documented in both patients, despite long histories of cognitive compromise and high likelihood of damage to the central nervous system.

Risperidone. A review of its pharmacology and therapeutic potential in the treatment of schizophrenia

Risperidone, a benzisoxazol derivative, is a novel antipsychotic agent which combines potent serotonin (5-hydroxytryptamine) 5-HT2 and dopamine D2 receptor antagonism. Development of the drug was stimulated by reports that the selective serotonin 5-HT2 antagonist ritanserin improved the negative symptoms of schizophrenia and decreased extrapyramidal symptoms when combined with haloperidol. The relatively low incidence of extrapyramidal symptoms with risperidone may reflect a preferential action on mesolimbic rather than nigrostriatal dopaminergic pathways. Recent clinical investigation suggests that risperidone is of at least comparable efficacy to haloperidol and perphenazine in improving the symptoms of acute and chronic schizophrenia on short term administration. Advantages offered by risperidone over haloperidol include a faster onset of antipsychotic action, a lower incidence of extrapyramidal effects and possibly greater efficacy against the negative symptoms of schizophrenia. If these benefits prove to be maintained during long term therapy, risperidone is likely to make a significant contribution to the treatment of schizophrenia.

In vivo dopamine-D2 and serotonin-5-HT2 receptor binding study of risperidone and haloperidol

An in vivo receptor binding technique was applied to evaluate the affinities of risperidone and haloperidol for dopamine-D2 receptors (D2) and serotonin-5-HT2 receptors (5-HT2) in rat brain with [3H]YM-09151-2 and [3H]ketanserin as selective ligands. Radioactivities were obtained in the striatum frontal cortex, and cerebellum of the rats treated with the ligands. Time course study of receptor occupancy at 25 to 250 min after single doses of the drugs (1 mg/kg, IP) showed higher 5-HT2 occupancy in the frontal cortex and lower D2 occupancy in the striatum by risperidone than by haloperidol. Dose-response analysis of receptor occupancy revealed risperidone demonstrated higher binding affinity for 5-HT2 than for D2, while the reverse was observed with haloperidol. It appeared that risperidone (1 mg/kg, IP), but not haloperidol (1 mg/kg, IP), demonstrated regional selectivity in D2 occupancy favouring frontal cortex more than the striatum. That risperidone displayed a higher ratio of 5-HT2 to D2 in occupancy than haloperidol is in agreement with the previous findings obtained in vitro.

Serotonin2 receptor-mediated excitation of interneurons in piriform cortex: antagonism by atypical antipsychotic drugs

Rat piriform cortex contains a subpopulation of presumed GABAergic interneurons located near the border of layers 2 and 3 that express excitatory serotonin2 receptors. These serotonin2-responsive interneurons send axons to layer 2 pyramidal cells. Using an in vitro brain slice preparation, serotonin2 receptor-mediated excitation can be assessed either by directly recording from the interneurons or by recording the increase in inhibitory postsynaptic potentials in the pyramidal cells. Intracellular recordings from the interneurons demonstrated that compared to pyramidal cells they had a more depolarized resting membrane potential, a higher input resistance and shorter action potential duration. The serotonin2 receptor-mediated excitation was associated with a strong depolarization (range 3-22 mV). We found that the atypical antipsychotic drugs, risperidone and clozapine, which have relatively high affinity for serotonin2 receptors, each dose-dependently inhibited the serotonin2-mediated excitation of the interneurons with IC50 values of 7 nM and 1.4 microM, respectively. This antagonism was specific to the extent that excitation mediated by agonists at excitatory amino acid receptors were not blocked at concentrations of risperidone and clozapine that completely antagonized the serotonin2 receptor-mediated excitation. The typical antipsychotic drug, chlorpromazine, inhibited the serotonin2-mediated excitation of the interneurons with an IC50 of 14 microM. Haloperidol, another typical antipsychotic drug, decreased the serotonin2 response to about half of baseline at a concentration of 10 microM (the exact IC50 could not be calculated because higher concentrations produced non-specific effects on cells). Both risperidone and clozapine blocked the serotonin-elicited inhibitory postsynaptic potentials in layer 2 pyramidal cells at concentrations that approximated the IC50 for antagonizing the serotonin2-mediated excitation of the interneurons. Chlorpromazine and haloperidol, in the concentration range that blocked serotonin2 receptor-mediated excitation of interneurons, also blocked the serotonin-elicited inhibitory postsynaptic potentials in the pyramidal cells. The IC50 values for risperidone and clozapine, but not for chlorpromazine or haloperidol, for blocking serotonin2 receptor-mediated actions in rodent piriform cortical slice are in the range of the plasma concentrations of the drug that are clinically efficacious. Our data suggest that a potential site of action of the atypical antipsychotic drugs risperidone and clozapine could be antagonism of serotonin acting through serotonin2 receptors on GABAergic interneurons in cerebral cortex.

Risperidone versus clozapine in the treatment of schizophrenic patients with acute symptoms: a double blind, randomized trial

1. In order to verify the hypothesis that risperidone is a useful therapeutic alternative to clozapine the authors carried out a randomized double blind trial in 59 patients with paranoid hallucinatory psychoses. 2. In a treatment lasting 28 days three groups of patients received either 4 mg risperidone (N = 20), 8 mg risperidone (N = 19), or 400 mg clozapine (N = 20) daily. 3. The tolerance of 4 mg risperidone was globally assessed as being better than that of 400 mg clozapine. Drop-outs under clozapine were mostly caused by side effects, whereas under risperidone they tended to occur for therapeutic inefficacy. 4. The antipsychotic effect was highly significant and clinically relevant under both risperidone and clozapine.

Risperidone versus perphenazine in the treatment of chronic schizophrenic patients with acute exacerbations

Risperidone (RIS), a new neuroleptic with 5-HT2- and dopamine D2 receptor-blocking properties, was compared with perphenazine (PER) in a double-blind, multicentre, parallel-group study in 107 chronic schizophrenics with acute exacerbation. RIS 5-15 mg or PER 16-48 mg daily was given for 8 weeks. Psychopathology was assessed with the Positive and Negative Syndrome Scale (PANSS) and Clinical Global Impression. Seventy-eight patients completed the trial; there was an equal number of dropouts on both drugs. The mean daily dose at endpoint was 8.5 mg RIS and 28 mg PER. The reduction in total PANSS score to endpoint did not differ significantly, although there was a tendency in favour of RIS. The number of patients with predominantly negative symptoms who showed at least 20% reduction in total PANSS score was significantly larger in the RIS group. Furthermore, the number of patients showing at least 20% reduction in Brief Psychiatric Rating Scale (BPRS) score (BPRS being a subscale of PANSS) was significantly larger in the RIS group. The hostility cluster of BPRS improved more on RIS than on PER in the endpoint analysis. The overall prevalence of side effects was fairly similar in the two groups.