Clozapine v. conventional antipsychotic drugs for treatment-resistant schizophrenia: a re-examination. Effectiveness of clozapine versus olanzapine, quetiapine, and risperidone in patients with chronic schizophrenia who did not respond to prior atypical antipsychotic treatment. Olanzapine versus clozapine in treatment-resistant or treatment-intolerant schizophrenia. Comparison of clozapine-amisulpride and clozapine-quetiapine combinations for patients with schizophrenia who are partially responsive to clozapine: a single-blind randomized study. Clozapine for the treatment-resistant schizophrenic. A double-blind comparison with chlorpromazine. Atypical antipsychotic agents in the treatment of violent patients with schizophrenia and schizoaffective disorder. Double-blind comparison of olanzapine versus clozapine in schizophrenic patients clinically eligible for treatment with clozapine. Adverse effects and laboratory parameters of high-dose olanzapine vs. clozapine in treatment-resistant schizophrenia. Some methodological considerations for the clinical evaluation of neuroleptics--comparative effects of clozapine and haloperidol on schizophrenics.
Although there is a consensus that clozapine is more effective than conventional antipsychotic drugs for treatment-resistant schizophrenia, there is great heterogeneity among results of relevant trials.
                To re-evaluate the evidence comparing clozapine with conventional antipsychotics and to investigate sources of heterogeneity.
                Individual studies were inspected with assessment of clinical relevance of results. Meta-regression analysis was performed to investigate sources of heterogeneity.
                Ten trials were examined. Recent large-scale studies have not found a substantial advantage for clozapine, especially in terms of a clinically relevant effect. Meta-regression showed that shorter study duration, financial support from a drug company and higher baseline symptom score consistently predicted greater advantage of clozapine.
                It may be inappropriate to combine studies in meta-analysis, given the degree of heterogeneity between their findings. The benefits of clozapine compared with conventional treatment may not be substantial. When a schizophrenia patient has an inadequate response to treatment with an antipsychotic drug, it is unclear what other antipsychotic to switch to and when to use clozapine. In this study, the authors compared switching to clozapine with switching to another atypical antipsychotic in patients who had discontinued treatment with a newer atypical antipsychotic in the context of the Clinical Antipsychotic Trials for Interventions Effectiveness (CATIE) investigation.
                Ninety-nine patients who discontinued treatment with olanzapine, quetiapine, risperidone, or ziprasidone in phase 1 or 1B of the trials, primarily because of inadequate efficacy, were randomly assigned to open-label treatment with clozapine (N=49) or blinded treatment with another newer atypical antipsychotic not previously received in the trial (olanzapine [N=19], quetiapine [N=15], or risperidone [N=16]).
                Time until treatment discontinuation for any reason was significantly longer for clozapine (median=10.5 months) than for quetiapine (median=3.3), or risperidone (median=2.8), but not for olanzapine (median=2.7). Time to discontinuation because of inadequate therapeutic effect was significantly longer for clozapine than for olanzapine, quetiapine, or risperidone. At 3-month assessments, Positive and Negative Syndrome Scale total scores had decreased more in patients treated with clozapine than in patients treated with quetiapine or risperidone but not olanzapine. One patient treated with clozapine developed agranulocytosis, and another developed eosinophilia; both required treatment discontinuation.
                For these patients with schizophrenia who prospectively failed to improve with an atypical antipsychotic, clozapine was more effective than switching to another newer atypical antipsychotic. Safety monitoring is necessary to detect and manage clozapine's serious side effects. Clozapine has been the gold standard for treatment of patients with refractory schizophrenia but is associated with serious safety liabilities. This has prompted the search for therapeutic alternatives for treatment-resistant schizophrenia. The objective of this study was to compare the efficacy and safety of olanzapine versus clozapine in schizophrenic patients who failed to respond adequately to antipsychotic medication or who experienced intolerable adverse effects associated with the medication. This 18-week, randomized, double-blind, parallel study compared treatment with either olanzapine (5-25 mg/day, n=75) or clozapine (100-500 mg/day, n=72) in patients with schizophrenia who were nonresponsive to, or intolerant of, standard acceptable antipsychotic therapy. At the 18-week endpoint, no statistically significant differences were found between olanzapine and clozapine in any efficacy measure used: Positive and Negative Syndrome Scale (PANSS) total, positive, negative, or general psychopathology or Clinical Global Impression severity (CGI-S). Response rates based on the criteria of Kane et al. [Arch. Gen. Psychiatry 45 (1988) 789] were also not significantly different between olanzapine-treated (57.9%) and clozapine-treated patients (60.8%). There were no significant differences in measurements of extrapyramidal symptoms or electrocardiography, and no clinically and statistically significant changes were seen in vital signs or laboratory measures in either group. Both treatments were well tolerated. Olanzapine demonstrated similar efficacy to clozapine in patients who had failed previous treatment because of lack of efficacy (treatment resistance) or intolerable side effects (treatment intolerance). Olanzapine therefore presents a safe alternative in the treatment of refractory schizophrenia. Schizophrenia is a devastating psychiatric disorder. Clozapine has long been the gold standard for treatment of patients with treatment-resistant schizophrenia; however, some patients are only partially responsive to clozapine treatment. Augmentation of clozapine treatment might enhance its effectiveness in partial responders, but only a few studies have investigated possible augmentation strategies. This study compared the effectiveness and tolerability of the combination of amisulpride and clozapine with the combination of quetiapine and clozapine in patients who were only partially responsive to clozapine monotherapy. Fifty-six treatment-resistant patients who were partially responsive to clozapine were randomly assigned to receive amisulpride or quetiapine along with an ongoing stable dose of clozapine. Fifty patients completed the study. Patients were evaluated at baseline and at the first, third, sixth, and eighth weeks. Efficacy measures consisted of the Brief Psychiatric Rating Scale (BPRS), the Scale for the Assessment of Negative Symptoms (SANS), the Scale for the Assessment of Positive Symptoms (SAPS), and the Clinical Global Impression (CGI) scale. Tolerability and adverse effects were assessed with the Udvalg for Kliniske Undersogelser (UKU) Side Effect Rating Scale and the Simpson Angus Scale (SAS). A substantial improvement occurred in both groups by the end of the eighth week; however, the improvement associated with amisulpride was significantly greater than that seen with quetiapine. This difference was noted as early as the third week of follow-up in terms of CGI scores, and by the sixth week with regard to BPRS, SANS, and SAPS scores. Both drugs were well tolerated, as measured by UKU and SAS. Improvement favoring clozapine+amisulpride could be attributed to the selective D2/D3 binding property of amisulpride, which had an additional effect in improving symptoms of schizophrenia. The authors concluded that amisulpride seems to be effective and well tolerated for augmentation purposes in clozapine-resistant patients. The treatment of schizophrenic patients who fail to respond to adequate trials of neuroleptics is a major challenge. Clozapine, an atypical antipsychotic drug, has long been of scientific interest, but its clinical development has been delayed because of an associated risk of agranulocytosis. This report describes a multicenter clinical trial to assess clozapine's efficacy in the treatment of patients who are refractory to neuroleptics. DSM-III schizophrenics who had failed to respond to at least three different neuroleptics underwent a prospective, single-blind trial of haloperidol (mean dosage, 61 +/- 14 mg/d) for six weeks. Patients whose condition remained unimproved were then randomly assigned, in a double-blind manner, to clozapine (up to 900 mg/d) or chlorpromazine (up to 1800 mg/d) for six weeks. Two hundred sixty-eight patients were entered in the double-blind comparison. When a priori criteria were used, 30% of the clozapine-treated patients were categorized as responders compared with 4% of chlorpromazine-treated patients. Clozapine produced significantly greater improvement on the Brief Psychiatric Rating Scale, Clinical Global Impression Scale, and Nurses' Observation Scale for Inpatient Evaluation; this improvement included "negative" as well as positive symptom areas. Although no cases of agranulocytosis occurred during this relatively brief study, in our view, the apparently increased comparative risk requires that the use of clozapine be limited to selected treatment-resistant patients. Violent behavior of patients with schizophrenia prolongs hospital stay and interferes with their integration into the community. Finding appropriate treatment of violent behaviors is of primary importance.
                To compare the efficacy of 2 atypical antipsychotic agents, clozapine and olanzapine, with one another and with haloperidol in the treatment of physical assaults and other aggressive behaviors in physically assaultive patients with schizophrenia and schizoaffective disorder.
                Randomized, double-blind, parallel-group, 12-week trial. Physically assaultive subjects with schizophrenia or schizoaffective disorder who were inpatients in state psychiatric facilities were randomly assigned to treatment with clozapine (n = 37), olanzapine (n = 37), or haloperidol (n = 36).
                Number and severity of physical assaults as measured by the Modified Overt Aggression Scale (MOAS) physical aggression score and the number and severity of all aggressive events as measured by the MOAS overall score. Psychiatric symptoms were assessed through the Positive and Negative Syndrome Scale (PANSS).
                Clozapine was superior to both olanzapine and haloperidol in reducing the number and severity of physical assaults as assessed by the MOAS physical aggression score and in reducing overall aggression as measured by the MOAS total score. Olanzapine was superior to haloperidol in reducing the number and severity of aggressive incidents on these 2 MOAS measures. There were no significant differences among the 3 medication groups in improvement of psychiatric symptoms as measured by the PANSS total score and the 3 PANSS subscales.
                Clozapine shows greater efficacy than olanzapine and olanzapine greater efficacy than haloperidol in reducing aggressive behavior. This antiaggressive effect appears to be separate from the antipsychotic and sedative action of these medications. The treatment of schizophrenic patients who fail to respond to adequate trials of neuroleptic drugs is a major challenge. Clozapine has been one treatment option; however, it is not universally effective and is limited in its use by safety concerns. With the introduction of newer agents, their performance relative to clozapine is of great clinical interest.
                The primary objective of this study was to evaluate the efficacy and safety of olanzapine versus clozapine among treatment resistant DSM-IV schizophrenic patients. The study was primarily designed to demonstrate the "noninferiority" of olanzapine compared to clozapine after 18 weeks of double-blind treatment. Conclusions were based on the one-sided lower 95% confidence limit about the treatment effect observed from the primary efficacy variable (Positive and Negative Syndrome Scale [PANSS] Total).
                Mean changes from baseline to end point in PANSS Total score, using a last observation carried forward technique, showed that both agents were comparably effective in neuroleptic resistant patients, i.e., demonstrated the "noninferiority" of olanzapine when compared to clozapine. Overall, significantly fewer olanzapine-treated patients (4%) discontinued for an adverse event than their clozapine-treated (14%) counterparts (p =.022). Among spontaneously reported adverse events, increased salivation, constipation, dizziness, and nausea were reported significantly more often among clozapine-treated patients, whereas only dry mouth was reported more often among olanzapine-treated patients.
                Olanzapine was demonstrated to be noninferior to clozapine and better tolerated among resistant schizophrenic patients clinically eligible for treatment with clozapine. Patients with treatment-resistant schizophrenia pose a major challenge to caregivers since only clozapine is documented as having superior efficacy in this population. Although olanzapine is similar to clozapine in structure and receptor profile, it has not been proven to have superior efficacy for this patient group. Nonetheless, olanzapine is being increasingly used in higher doses as clinicians attempt to find a more effective and tolerable therapy for refractory patients. Furthermore, there are little data comparing olanzapine and clozapine in this population. Thirteen patients participated in a randomized double-blind 16-week crossover study of clozapine therapy (450 mg/day) compared to high doses of olanzapine (50 mg/day). No patients on olanzapine responded while 20% responded to clozapine treatment. Olanzapine patients tended to experience higher rates of anticholinergic effects such as dry mouth (80 vs. 20%) and blurry vision (40 vs. 0%). Clozapine-treated patients had higher rates of sialorrhea (80 vs. 10%), sweating (50 vs. 10%), dyspepsia (70 vs. 30%), and lethargy (90 vs. 60%). Neither treatment was associated with significant akathisia. Liver enzyme elevation and lipids were higher with clozapine treatment. Mean weight gain in the initial 8 weeks was 3.4 kg for olanzapine and 1.2 kg for clozapine. High doses of olanzapine during 8 weeks of treatment did not increase lipids and liver enzymes like clozapine did. Olanzapine at 50 mg/day may be associated with more anticholinergic effects and weight gain than clozapine. For the purpose of evaluating objectively the characteristics of clinical effects of clozapine and haloperidol, a double-blind comparative trial was conducted on 91 schizophrenic in-patients. The changes of symptoms were assessed by means of several psychiatric and behavioral rating scales. The results were analyzed by means of nonparametric statistical methods. Furthermore, application of multivariate analysis was considered. After 12 weeks of treatment, though no significant difference in general improvement rate was noted between the two groups, a marked different spectrum of clinical effects was observed according to the rating scales. Clozapine is superior in anti-delusional, contact-promoting and sedative anxiolytic effect, while haloperidol is superior in anti-autistic effect. Among the side-effects, extrapyramidal symptoms appeared significatly more severe in the haloperidol group. The frequency of appearance of fever, was significantly greater in the clozapine group than the other. The four dropout cases of the clozapine group were all caused by fever. Through this clinical trial, clinical availability and validity of various statistical analytical methods were reconsidered.
The equal effectiveness and tolerability of new atypical drugs in comparison with clozapine is not yet demonstrated. Lack of statistical power to determine the comparative efficacy and effectiveness of newer atypical drugs makes it difficult to judge whether newer drugs are more effective, less effective or equivalent. Trials of sufficient power, with longer duration, measuring clinically important outcomes, are needed to assess the true comparative clinical effectiveness, tolerability and cost effectiveness of newer drugs in relation to clozapine.