Treatment with clozapine and its effect on plasma homovanillic acid and norepinephrine concentrations in schizophrenia

Differential effects of different antipsychotic drugs on cognitive function in patients with chronic schizophrenia

BACKGROUND

Cognitive impairment is core feature of schizophrenia. The impact of antipsychotics on cognition remains controversial. This study aimed to examine the effects of long-term use of different types of antipsychotics on cognitive impairment in schizophrenia patients.

METHODS

We used the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) to assess the cognition of three groups of schizophrenia patients (318 on clozapine, 125 on risperidone, and 166 on typical antipsychotic drugs) and 399 healthy controls, and used the Positive and Negative Syndrome Scale to assess schizophrenia symptoms of patients.

RESULTS

Patients taking typical antipsychotics scored higher on the immediate memory and delayed memory index than those taking clozapine or risperidone (all p < 0.01). Patients taking clozapine scored higher on the language subscale than those taking risperidone (p < 0.05). Multiple regression analysis showed that the drug type was identified as an independent contributor to the immediate memory, language, and delayed memory index of RBANS (all p < 0.05).

CONCLUSIONS

Patients taking typical antipsychotics have better memory than those taking clozapine or risperidone. Patients taking clozapine have better language function than those taking risperidone.

Demographic and clinical features as predictors of clozapine response in patients with schizophrenia spectrum disorders: A systematic review and meta-analysis

OBJECTIVES

Clozapine (CLZ) is prescribed to (relatively) treatment-resistant patients with schizophrenia spectrum disorders. Currently, it is unknown what factors predict response to CLZ. Therefore, we performed meta-analyses to identify predictors of CLZ response, hence aiming to facilitate timely and efficient prescribing of CLZ.

METHODS

A systematic search was performed in 'Pubmed' and 'Embase' until 1 January 2019. Articles were eligible if they provided data on predictors of CLZ response measured demographic and clinical factors at baseline or biochemical factors at follow-up in schizophrenia spectrum disorder patients.

RESULTS

A total of 34 articles, total number of participants = 9386; N unique = 2094, were eligible. Factors significantly associated with better CLZ response were: lower age, lower PANSS negative score and paranoid schizophrenia subtype.

CONCLUSION

The results of our meta-analyses suggest that three baseline demographic and clinical features are associated with better clozapine response, i.e. relatively young age, few negative symptoms and paranoid schizophrenia subtype. These variables may be taken into account by clinicians who consider treating a specific patient with CLZ.

Blood Pressure and Heart Rate Changes During Clozapine Treatment

People with schizophrenia are 3-4 times more likely to die from cardiovascular disease than the general population. Clozapine (CLZ) is the gold standard of treatment for refractory schizophrenia. It has been associated with tachycardia and recent evidence shows individuals prescribed CLZ may develop blood pressure (BP) elevation and hypertension. The purpose of this study was to examine the effects of CLZ on BP and heart rate (HR). This was a retrospective chart review of patients 18-75 years old with a DSM IV diagnosis of Schizophrenia or Schizoaffective disorder. Primary outcomes were systolic blood pressure (SBP), diastolic blood pressure (DBP), and HR measured 12 weeks before and 24 weeks during CLZ treatment. Eighteen patient records were included in this study. The mean stabilized CLZ dose was 441.7 ± 171.8 mg/day. DBP (t = 1.02, df = 79.5, = 2.00, 0.049) and HR (t = 1.32, df = 355  = -4.61, < 0.0001) were significantly higher after CLZ initiation. A trend was noted for increase in SBP (p = 0.071). 22 % of patients met criteria for hypertension before CLZ and 67 % during CLZ treatment (Chi Square = 6.25, df = 1, p = 0.0124). No significant changes in weight or renal function occured during CLZ treatment. No patients had evidence of cardiomyopathy. The data suggest CLZ may be associated with a rise in BP and HR. The results of this study support previous literature that found an increase in SBP/DBP regardless of CLZ dose, occurring early in treatment. Due to high risk of cardiovascular morbidity and mortality, more work is needed to determine risk factors and understand the mechanism of action that may cause this side effect.

Clozapine-induced hypertension: A case report and review of literature

There are very few reports which suggest an association between clozapine and hypertension. We report a case in which a direct link of initiation of clozapine to development of hypertension which required pharmacological intervention. A 32-year-old male who did not have any history of hypertension and had normal blood pressure at the baseline developed high blood pressure (i.e., 150/90 mmHg) while on clozapine 100 mg/day. Reduction of the dose of clozapine to 75 mg/day led to the return of blood pressure to baseline, with increase in blood pressure to 150/90 mmHg on increasing the dose of clozapine again, requiring tablet atenolol 50 mg/day for normalization of blood pressure with concomitant continuation of atenolol. Later, clozapine was increased to 350 mg/day, with no recurrence of raise in blood pressure. After 6 months, tablet atenolol was stopped with no evidence of hypertension in follow-up. To conclude, this case report suggests that clozapine can rarely lead to hypertension during the initial phase of treatment.

Relationship between plasma homovanillic acid and outcome in patients with psychosis spectrum disorders

BACKGROUND

Psychosis spectrum disorders, especially schizophrenia, have been linked to disturbed dopaminergic activity in the brain. Plasma homovanillic acid (pHVA) levels partly represent dopaminergic metabolism in the central nervous system. In the present study associations between (changes in) pHVA levels, symptom severity and symptomatic improvement in patients with psychoses were investigated.

METHODS

From a total of 80 patients, 58 fulfilled all inclusion criteria and their symptom profile and severity were assessed by means of the Comprehensive Assessment of Symptoms and History (CASH), the Positive and Negative Syndrome Scale (PANSS) and the Clinical Global Impression Scale for Severity and Improvement (CGI-S/CGI-I) at baseline and after 6 weeks of antipsychotic treatment. After inclusion, all patients were prescribed first- or second-generation antipsychotics by their treating psychiatrist. A total of 12 patients had first-episode psychosis (FEP). At both time points, pHVA levels were measured. Subsequently, pHVA levels were compared with an age-matched control sample and changes in pHVA levels (ΔpHVA) after treatment were associated with clinical parameters.

RESULTS

Before analyses, data were scrutinized for possible confounders, particularly gender, smoking, medication status (including antipsychotic class), and recent drug use. The pHVA levels in patients were not different from those in controls. Treatment resulted in a significant decrease of all parameters. Symptomatic improvement as well as ΔpHVA was most pronounced in FEP patients.

CONCLUSION

These findings show that patients with FEP have a more favourable outcome than non-FEP patients and that greater ΔpHVA also suggests that FEP patients still have the capacity to adjust dopaminergic neurotransmission.

Rare and very rare adverse effects of clozapine

Clozapine (CLZ) is the drug of choice for the treatment of resistant schizophrenia; however, its suitable use is limited by the complex adverse effects' profile. The best-described adverse effects in the literature are represented by agranulocytosis, myocarditis, sedation, weight gain, hypotension, and drooling; nevertheless, there are other known adverse effects that psychiatrists should readily recognize and manage. This review covers the "rare" and "very rare" known adverse effects of CLZ, which have been accurately described in literature. An extensive search on the basis of predefined criteria was made using CLZ and its combination with adverse effects as keywords in electronic databases. Data show the association between the use of CLZ and uncommon adverse effects, including ischemic colitis, paralytic ileus, hematemesis, gastroesophageal reflux disease, priapism, urinary incontinence, pityriasis rosea, intertriginous erythema, pulmonary thromboembolism, pseudo-pheochromocytoma, periorbital edema, and parotitis, which are influenced by other variables including age, early diagnosis, and previous/current pharmacological therapies. Some of these adverse effects, although unpredictable, are often manageable if promptly recognized and treated. Others are serious and potentially life-threatening. However, an adequate knowledge of the drug, clinical vigilance, and rapid intervention can drastically reduce the morbidity and mortality related to CLZ treatment.

Clozapine use presenting with pseudopheochromocytoma in a schizophrenic patient: a case report

Introduction. There have been six previous cases that reported pseudopheochromocytoma in patients taking clozapine. Our case showed the direct link of clozapine to serum levels of certain markers. Case. This is a case of a 49-year-old obese Caucasian female who was referred to endocrinology for investigation of Cushing's syndrome, based on raised blood pressure and Cushingoid facies. The patient had underlying schizophrenia and was stable on clozapine. Her blood pressure was 150/99 mmHg on bendroflumethiazide and candesartan. We measured her 24-hour urinary-free cortisol, which was normal but 24-hour urinary-free noradrenaline was elevated at 835 nmol (76–561) with normal adrenaline 36 nmol (7–82) and dopamine 2679 nmol (366–2879), as the patient had history of palpitations and sweating. Two sets of 24-hour urinary-free cortisol measurements were normal and serum cortisol suppressed to <50 nmol/l after a 1 mg overnight dexamethasone. Two further 24-hour urinary-free catecholamines showed a raised level of noradrenaline. MRI demonstrated normal adrenals and MIBG scan did not show any abnormal uptake at adrenal glands. Conclusion. Pseudopheochromocytoma has been reported in patients taking clozapine. A number of different mechanisms for raised plasma noradrenaline levels with clozapine have been postulated. The above case highlights an unusual but known side effect of clozapine.

New insights on the consequences of biotransformation processes on the distribution and pharmacodynamic profiles of some neuropsychotropic drugs

The metabolic processes frequently trigger highly complex pharmacokinetic (PK) and pharmacodynamic (PD) characteristics for the coexisting entities, parent drug and its active or inactive metabolites. The interpretation of both individual and cumulative profiles, frequently used in the therapeutic drug monitoring procedures, must take into consideration the biological coherence of the changes of the molecular descriptors characterizing the metabolites versus the parent drugs, and further qualitative and quantitative consequences on permeability processes across highly specialized biological barriers (e.g. blood-brain barrier [BBB]). This paper analyzes the correlation of molecular descriptor differences and the PK/PD consequences for three representative psychotropic drugs (risperidone, clozapine and tramadol) and their active metabolites, underlying the safety and efficacy concerns of using the products of metabolic processes as potential new drugs. The minimal structural changes are correlated with the predicted or experimental penetrability across the biological membranes, with a special emphasis on BBB penetration, as the limiting phase for the effect at central nervous system level. The PD characteristics related to the active metabolites are compared to the ones reported for the parent drugs, concerning mainly the affinity for cerebral receptors and the type of activity at a specific level. For the neuropsychotropic substances, with BBB penetrability as a sine qua non condition, the comparative analysis of PK/PD properties for the parent drug and its metabolites generates a complete and highly complex image of the consequences of their coexistence, since these entities must be conceived and analyzed not separately, but by inclusion of usually complementary properties generating a unique therapeutic profile.

Effects of aripiprazole and the Taq1A polymorphism in the dopamine D2 receptor gene on the clinical response and plasma monoamine metabolites level during the acute phase of schizophrenia

The Taq1A polymorphism in the dopamine D2 receptor (DRD2) gene could be related to the response to antipsychotics. We examined the effects of the Taq1A polymorphism on the plasma monoamine metabolites during the treatment of schizophrenia with aripiprazole, a DRD2 partial agonist. Thirty Japanese patients with schizophrenia were treated with aripiprazole for 6 weeks. We measured plasma levels of homovanillic acid (pHVA) and 3-methoxy-4hydroxyphenylglycol (pMHPG) before and after treatment. The Taq1A polymorphism was genotyped with polymerase chain reaction. Aripiprazole improved the acute symptoms of schizophrenia and decreased pHVA in responders (P = 0.023) but not in nonresponders (P = 0.28). Although A1 allele carriers showed a tendency to respond to aripiprazole (61.5%) compared to A1 allele noncarriers (29.4%) (P = 0.078), there was not statistically significant difference in the response between the 2 genotype groups. There were significant effect for response (P = 0.013) and genotype × response interaction (P = 0.043) on the change of pHVA. The changes of pHVA differ between responders and nonresponders in A1 allele carriers but not in A1 allele noncarriers. There were no genotype or response effects or genotype × response interaction on the changes of the plasma levels of 3-methoxy-4hydroxyphenylglycol. Our preliminary results suggest that Taq1A polymorphism may be partly associated with changes in pHVA during acute schizophrenia.

Review: The biological basis of antipsychotic response in schizophrenia

Schizophrenia is a severe mental illness affecting approximately 1% of the population worldwide. Antipsychotic drugs are effective in symptom control in up to two-thirds of patients, but in at least one-third of patients the response is poor. The reason for this is not clear, but one possibility is that good and poor responders have different neurochemical pathologies, and may therefore benefit from different treatment approaches. In this selective review we summarise research findings investigating the biological differences between patients with schizophrenia who show a good or a poor response to treatment with antipsychotic drugs.

Plasma homovanillic acid differences in clinical subgroups of first episode schizophrenic patients

This study evaluates the relationship between plasma homovanillic acid (pHVA) levels, which have been used to study the role of central dopamine in schizophrenia, and the positive/negative syndrome in first episode schizophrenic patients before and after antipsychotic treatment. Forty neuroleptic-naive first episode schizophrenic patients were monitored at baseline and on days 7, 14 and 28. Clinical status was evaluated with the Scale for the Assessment of Positive Symptoms (SAPS), the Scale for the Assessment of Negative Symptoms (SANS), and the Brief Psychotic Rating Scale. Plasma HVA levels were also measured. Patients were divided into predominantly positive or negative syndrome groups by subtracting SAPS from SANS scores, at baseline. A healthy control group was also enrolled. Schizophrenic patients as a group had significantly higher pHVA levels than controls at baseline (20.50+/-11.85 vs. 13.04+/-7.22 ng/ml). Moreover, 12 predominantly negative syndrome patients had similar mean baseline pHVA levels (21.30+/-12.36 ng/ml) to those of 28 predominantly positive syndrome patients (19.40+/-11.33 ng/ml). During follow-up, there was a different evolution of pHVA levels in the predominantly positive syndrome group than in the predominantly negative syndrome group, with a significantly greater global reduction of pHVA levels in the former. Although both groups showed clinical improvement following 4 weeks of treatment with risperidone, pHVA levels at endpoint were lower (13.29+/-5.91 ng/ml) than at baseline in patients in the predominantly positive syndrome group, while among those in the predominantly negative syndrome group there was no difference in pHVA levels before and after treatment (21.02+/-13.06 ng/ml). The different pHVA level profiles observed in predominantly positive and negative syndrome first episode patients after 4 weeks of treatment with risperidone suggest that each syndrome may have a different underlying neurobiology.

Clozapine versus typical neuroleptic medication for schizophrenia

BACKGROUND

Long-term drug treatment of schizophrenia with typical antipsychotics has limitations: 25 to 33% of patients have illnesses that are treatment-resistant. Clozapine is an antipsychotic drug, which is claimed to have superior efficacy and to cause fewer motor adverse effects than typical drugs for people with treatment-resistant illnesses. Clozapine carries a significant risk of serious blood disorders, which necessitates mandatory weekly blood monitoring at least during the first months of treatment.

OBJECTIVES

To evaluate the effects of clozapine compared with typical antipsychotic drugs in people with schizophrenia.

SEARCH STRATEGY

For the current update of this review (March 2006) we searched the Cochrane Schizophrenia Group Trials Register.

SELECTION CRITERIA

All relevant randomised clinical trials (RCTs).

DATA COLLECTION AND ANALYSIS

We extracted data independently. For dichotomous data we calculated relative risks (RR) and their 95% confidence intervals (CI) on an intention-to-treat basis, based on a fixed-effect model. We calculated numbers needed to treat/harm (NNT/NNH) where appropriate. For continuous data, we calculated weighted mean differences (WMD) again based on a fixed-effect model.

MAIN RESULTS

We have included 42 trials (3950 participants) in this review. Twenty-eight of the included studies are less than 13 weeks in duration, and, overall, trials were at significant risk of bias. We found no significant difference in the effects of clozapine and typical neuroleptic drugs for broad outcomes such as mortality, ability to work or suitability for discharge at the end of the study. Clinical improvements were seen more frequently in those taking clozapine (n=1119, 14 RCTs, RR 0.72 CI 0.7 to 0.8, NNT 6 CI 5 to 8). Also, participants given clozapine had fewer relapses than those on typical antipsychotic drugs (n=1303, RR 0.62 CI 0.5 to 0.8, NNT 21 CI 15 to 49). BPRS scores showed a greater reduction of symptoms in clozapine-treated patients, (n=1145, 16 RCTs, WMD -4.22 CI -5.4 to -3.1), although the data were heterogeneous (Chi(2) 0.0001, I(2) 66%). Short-term data from the SANS negative symptom scores favoured clozapine (n=196, 5 RCTs, WMD -5.92 CI -7.8 to -4.1). We found clozapine to be more acceptable in long-term treatment than conventional antipsychotic drugs (n=982, 16 RCTs, RR 0.60 CI 0.5 to 0.7, NNT 15 CI 12 to 20). Blood problems occurred more frequently in participants receiving clozapine (3.2%) compared with those given typical antipsychotics (0%) (n=1031, 13 RCTs, RR 7.09 CI 2.0 to 25.6). Clozapine participants experienced more drowsiness, hypersalivation, or temperature increase, than those given conventional neuroleptics. However, clozapine patients experienced fewer motor adverse effects (n=1433, 18 RCTs, RR 0.58 CI 0.5 to 0.7, NNT 5 CI 4 to 6).The clinical effects of clozapine were more pronounced in participants resistant to typical neuroleptics in terms of clinical improvement (n=370, 4 RCTs, RR 0.71 CI 0.6 to 0.8, NNT 4 CI 3 to 6) and symptom reduction. Thirty-four per cent of treatment-resistant participants had a clinical improvement with clozapine treatment.

AUTHORS' CONCLUSIONS

Clozapine may be more effective in reducing symptoms of schizophrenia, producing clinically meaningful improvements and postponing relapse, than typical antipsychotic drugs - but data are weak and prone to bias. Participants were more satisfied with clozapine treatment than with typical neuroleptic treatment. The clinical effect of clozapine, however, is, at least in the short term, not reflected in measures of global functioning such as ability to leave the hospital and maintain an occupation. The short-term benefits of clozapine have to be weighed against the risk of adverse effects. Within the context of trials, the potentially dangerous white blood cell decline seems to be more frequent in children and adolescents and in the elderly than in young adults or people of middle-age.The existing trials have largely neglected to assess the views of participants and their families on clozapine. More community-based long-term randomised trials are needed to evaluate the efficacy of clozapine on global and social functioning as trials in special groups such as people with learning disabilities.

Correlation Between Plasma Homovanillic Acid Levels and the Response to Atypical Antipsychotics in Male Patients With Schizophrenia

OBJECTIVE

The authors investigated the effects of atypical antipsychotic drugs-olanzapine, perospirone, and quetiapine-on plasma homovanillic acid (pHVA) in male patients with chronic schizophrenia.

METHODS

In this prospective, open-label study, the subjects were 30 inpatients who were diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, criteria for schizophrenia. The authors switched patients from typical antipsychotic drugs to olanzapine, perospirone, or quetiapine. Each patient gave informed consent for the research. pHVA was assessed before and after switching medications.

RESULTS

After the switch, the authors found a significant improvement in psychotic symptoms, nonsignificant improvement in extrapyramidal symptoms, and a nonsignificant reduction in pHVA. In addition, the baseline pHVA correlated positively with the score changes from baseline in the Brief Psychiatric Rating Scale (BPRS) total, positive, and negative symptoms in the group with a whole sample and in the olanzapine-treated group, and with the score changes in the BPRS total and positive symptoms in the quetiapine-treated group.

CONCLUSION

Our findings indicated that the preswitching pHVA levels could be used to predict changes in the psychotic symptoms of male patients with chronic schizophrenia when switching to atypical antipsychotic drugs.

Predictors and markers of clozapine response

RATIONALE

With other atypical antipsychotics now available, having predictors of clozapine response would be of considerable value, offering clinicians guidance in their decision as to when, and if, a trial of clozapine is warranted.

OBJECTIVES

The aim was to review existing evidence regarding identified predictors and markers of clozapine response.

METHODS

Relevant studies were identified through PUBMED searches (1975-June 2004) and cross-referencing of reviews and included studies. The data were summarized under two main categories: clinical (general, neurological, cognitive/neuropsychological, clozapine levels) and biological (biochemical, endocrine, genetic, metabolic, morphological, dopamine D2 receptor occupancy). 'Reliable' predictors/markers were defined a priori as those with support of at least two independent reports that addressed overall response, with no contradictory findings to date. 'Potential' predictors/markers had the support of a single report that addressed overall response and at least one other evaluating treatment outcome but not directly addressing response status.

RESULTS AND CONCLUSIONS

Higher baseline clinical symptoms and functioning in the previous years and low cerebrospinal homovanillic acid/5-hydroxyindoleacetic acid levels were identified as reliable. Three potential measures were identified: reduction of frontal cortex metabolic activity, reduction of caudate volume, and improvement in P50 sensory gating.

Long-term pharmacoclinical follow-up in schizophrenic patients treated with risperidone. Plasma and red blood cell concentrations of risperidone and its 9-hydroxymetabolite and their relationship to whole blood serotonin and tryptophan, plasma homovanillic acid, 5-hydroxyindoleacetic acid, dihydroxyphenylethyleneglycol and clinical evaluations

The aim of the study was to establish a relationship between the clinical efficacy of risperidone (Risp), the biological levels of Risp and its metabolite, 9-hydroxyrisperidone (9-OH-Risp), and the turnover of blood biogenic amines during a long-term treatment (1 year). Risp is one of the newer atypical antipsychotic drugs with potent serotonin (5HT2), moderate D2 and real alpha 1-alpha 2 adrenoreceptor antagonistic effects. The study has been performed in an open setting and included 17 patients, but only 15 were followed-up from 3 to 12 months. Pharmacokinetic analyses were conducted at the same time as clinical evaluations, grading using the Positive and Negative Syndrome Scale (PANSS), the Clinical Global Impressions (CGI), the Global Assessment of Functioning Scale (GAF), the Quality of Life Scale (QLS) and the Extrapyramidal Symptoms Rating Scale (ESRS) and the determinations of plasma and red blood cell (RBC) Risp and 9-OH-Risp, whole blood 5HT and tryptophan (Trp), plasma homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5HIAA) and dihydroxyphenylethyleneglycol (DHPG). The therapeutic drug monitoring needed oral Risp daily dose of 4.5 +/- 2.3 mg (range 2-8) and the stabilized concentrations (ng/ml) at endpoint in plasma and RBC were 10 +/- 8 (range 1-23) and 3.5 +/- 2 (range 1-8) for Risp and 29 +/- 19 (range 8-70) and 11.5 +/- 6.6 (range 2.6-22.5) for 9-OH-Risp, respectively. 9-OH-Risp appears to be the major active metabolite compound at higher concentrations than Risp. Positive linear correlations were found only between plasma and RBC 9-OH-Risp and the daily dose and the score of the GAF. Statistically significant clinical results showed that Risp is a potent antipsychotic agent efficacious both on positive and negative symptoms and on quality of life. Positive symptoms decreased after about the second month and the negative symptoms improved secondly. Patients (n = 8) who responded to Risp were characterized, on the long-term, by a statistically significant decrease of whole blood 5HT and increase of plasma DHPG.

Auditory P50 in schizophrenics on clozapine: improved gating parallels clinical improvement and changes in plasma 3-methoxy-4-hydroxyphenylglycol

Schizophrenic patients have decreased inhibition of the P50 auditory evoked potential response to the second of two paired click stimuli delivered 500 ms apart. This deficit in inhibitory gating does not change during treatment with typical neuroleptics. We recently reported that neuroleptic-resistant schizophrenics had enhanced P50 gating after 1 month of clozapine treatment, if they responded with decreased clinical symptoms. This study reports the outcome of more prolonged treatment. Ten treatment-refractory schizophrenic patients were studied at baseline, after 1 month on clozapine, and again after 15 +/- 6.1 (SD) months of clozapine treatment. Eight subjects reached a clinically stable improved state, at which time they had significantly improved P50 auditory gating. One patient had a return of impaired gating after stopping clozapine, as did another during a clinical relapse. Decreasing plasma 3-methoxy-4-hydroxyphenylglycol levels with clozapine treatment were correlated with improved P50 gating and improved Brief Bsychiatric Rating Scale-positive scores. This study provides further evidence that improved P50 gating in schizophrenic patients treated with clozapine coincides with clinical improvement and that this improvement can be sustained for at least 1 year.

Cardiovascular autonomic reactivity in schizophrenics under neuroleptic treatment: A potential predictor of short-term outcome?

In schizophrenics cardiovascular autonomic reactivity (CAR) can be used as an indicator of autonomic arousal. Using a standardized autonomic test battery (modified according to Ewing and Clarke) we prospectively compared the CAR between 46 actually ill schizophrenics (diagnosis according to DSM-III-R) treated with either haloperidol (n = 26) or clozapine (n = 20) and 30 well-matched healthy volunteers. Multivariate analysis demonstrated a significant effect of neuroleptic medication (haloperidol vs. clozapine) on heart rate and diastolic blood pressure under resting conditions as well as on the heart rate variance (30:15 ratio, deep-breathing, Valsalva) and blood pressure tests (sustained handgrip, Schellong). In addition a positive treatment response (using predefined outcome criteria of the Brief Psychiatric Rating Scale) was independently associated with lower resting heart rates and less impaired 30:15 ratios under neuroleptic medication. Our data indicate that clozapine treatment was associated with a substantial impairment of CAR, which can be explained by the drug's anticholinergic properties in combination with an increase in norepinephrine outflow. The greater heart rate variability in responders might be due to an early neuroleptic-induced decrease of sympathetic activity in the autonomic nervous system, which may precede clinical improvement. Our findings are discussed in relation to neuroleptic-induced changes in plasma catecholamine levels suggested to be useful biological markers in predicting treatment outcome.

Clozapine versus typical neuroleptic medication for schizophrenia

BACKGROUND

Long-term drug treatment of schizophrenia with conventional antipsychotics has limitations: 25-33% of patients have illnesses that are treatment-resistant. Clozapine is an atypical antipsychotic drug, which is claimed to have superior efficacy and to cause fewer motor adverse effects than typical drugs for people with treatment-resistant illnesses. Clozapine carries a significant risk of serious blood disorders, which necessitates mandatory weekly blood monitoring at least during the first months of treatment.

OBJECTIVES

To evaluate the effects of clozapine for schizophrenia in comparison to typical antipsychotic drugs.

SEARCH STRATEGY

Publications in all languages were searched from the following databases: Biological Abstracts (1982-1999), The Cochrane Library CENTRAL (Issue 2, 1999), Cochrane Schizophrenia Group's Specialised Register (1999), EMbase (1980-1999), ISI Citation Index, LILACS (1982-1999), MEDLINE (1966-1999), and PsycLIT (1974-1999). Reference list screening of included papers was performed. Authors of recent trials and the manufacturer of clozapine contacted.

SELECTION CRITERIA

All randomised controlled trials comparing clozapine with typical antipsychotic drugs were included by independent assessment by at least two reviewers.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by at least two reviewers. Authors of trials published since 1980 were contacted for additional and missing data. Odds ratios (OR) and 95% confidence intervals (CI) of homogeneous dichotomous data were calculated with the Peto method. A random effects model was used for heterogeneous dichotomous data. Where possible the numbers needed to treat (NNT) or needed to harm (NNH) were also calculated. Weighted or standardised means were calculated for continuous data.

MAIN RESULTS

Currently the review includes 31 studies, 26 of which are less than 13 weeks in duration. These studies include 2589 participants, most of whom were men (74%). The average age was 38 years. There was no difference in the effects of clozapine and typical neuroleptic drugs for broad outcomes such as mortality, ability to work or suitability for discharge at end of the study. Clinical improvement was seen more frequently in those taking clozapine (random effects OR 0.4 CI 0.2-0.6, NNT 6) both in the short and the long term. Also, in the short term, participants on clozapine had fewer relapses than those on typical antipsychotic drugs (OR 0.6 CI 0.4-0.8, NNT 20 CI 17-38), and this may be true for long-term treatment as well. Symptom assessment scales showed a greater reduction of symptoms in clozapine-treated patients. Clozapine treatment was more acceptable than low-potency antipsychotics such as chlorpromazine (OR 0.6 CI 0.4-0.9) but did not differ from acceptability of high-potency neuroleptics such as haloperidol (random effects OR 0.8 CI 0.4-1.5). Clozapine was more acceptable in long-term treatment than conventional antipsychotic drugs (random effects OR 0.4 CI 0.2-0.7, NNT 6 CI 3-111). Patients were more satisfied with clozapine treatment (OR 0.5 CI 0.3-0.8, NNT 12 CI 7-37), but they experienced more hypersalivation, temperature increase, and drowsiness than those given conventional neuroleptics. However, clozapine patients experience fewer motor side effects and less dry mouth. The clinical efficacy of clozapine was more pronounced in participants resistant to typical neuroleptics in terms of clinical improvement (random effects OR 0.2 CI 0.1-0.5, NNT 5 CI 4-7) and symptom reduction. Thirty-two percent of treatment resistant people had a clinical improvement with clozapine treatment.

REVIEWER'S CONCLUSIONS

This systematic review confirms that clozapine is convincingly more effective than typical antipsychotic drugs in reducing symptoms of schizophrenia, producing clinically meaningful improvements and postponing relapse. Patients were more satisfied with clozapine treatment than with typical neuroleptic treatment. (ABSTRACT TRUNCATED

Risperidone-induced increase of plasma norepinephrine is not correlated with symptom improvement in chronic schizophrenia

BACKGROUND

Previous studies have shown an increase in plasma levels of norepinephrine (NE) after clozapine treatment of schizophrenia. This effect has been suggested to relate to improvement in symptoms.

METHODS

To test whether other novel antipsychotic drugs have such an effect, the present experiment examined schizophrenic symptoms and plasma levels of NE before and after 5 weeks of treatment with risperidone or haloperidol.

RESULTS

Risperidone, but not haloperidol, significantly increased plasma NE; however, there was no correlation of this effect with clinical improvement on any symptom scale.

CONCLUSIONS

This finding suggests that risperidone shares similar properties with clozapine in enhancing peripheral NE, but that these changes in plasma NE may not be a consistent indicator of atypical antipsychotic drug efficacy.

Neurochemical variables in schizophrenic patients during switching from neuroleptics to clozapine

1. The study aimed to search for the effect of clozapine on the levels of the main metabolites of dopamine homovanillic acid (HVA), serotonin 5-hydroxyindoleacetic acid (5-HIAA) and norepinephrine 3-methoxy-4-hydroxyphenylglycol (MHPG) in urine as well as on plasma levels of HVA, 5-HIAA, prolactin (PRL) and cortisol. 2. Seventeen male patients diagnosed as suffering from DSM-IIIR schizophrenia completed the study. 3. The patients were switched from classical antipsychotics to clozapine. After six weeks treatment with clozapine the severity of psychopathology (total BPRS score) decreased significantly (p = 0.00004). pHVA and -5-HIAA did not change significantly. uMHPG increased significantly (p = 0.017). Both PRL and cortisol levels decreased significantly (p = 0.0002, p = 0.032 respectively). Patients with high HVA levels in both plasma and urine at baseline had a lower BPRS score at the end of treatment period (p = 0.0001, p = 0.049 respectively).

Evolution of plasma homovanillic acid (HVA) in chronic schizophrenic patients treated with haloperidol

In a 4-week study of 14 drug-free schizophrenic patients (according to DSM-III-R), free and conjugated fractions of plasma homovanillic acid (pHVA) were repeatedly measured. Free HVA levels decreased during the first 2 h of haloperidol intake (P < 0.03). Conjugated HVA levels slowly decreased during the following weeks (P < 0.05), while free HVA levels remained stable. After 4 weeks, free HVA levels remained unchanged 2 h after morning haloperidol intake, but conjugated HVA levels tended to increase. In haloperidol responders, at baseline the free/total HVA ratio was significantly higher than that in non-responders (P < 0.01). Tolerant patients, i.e. those whose post-treatment free HVA levels decreased below pre-treatment levels, were not found to respond better to haloperidol than non-tolerant patients. The balance between free and conjugated pHVA may be a better reflection of the action of haloperidol than free pHVA levels and it may be of prognostic value in terms of drug response.

Prediction of short-term changes in symptom severity by baseline plasma homovanillic acid levels in schizophrenic patients receiving clozapine

The relationship between pretreatment levels of plasma homovanillic acid (pHVA) and the outcome of clozapine treatment was studied in 18 male patients with schizophrenia who were resistant to treatment with conventional neuroleptics. After 6 months of clozapine treatment, 7 patients demonstrated > or = 20% decrease in the Brief Psychiatric Rating Scale (BPRS) (responders), while 11 patients did not (non-responders). Responders and non-responders did not differ with respect to the baseline pHVA level. The BPRS Positive Symptom scores at 6 weeks and 3 months, but not those at baseline and 6 months, following initiation of clozapine treatment negatively correlated with pHVA levels for all patients. The correlations became stronger when only responders were included. No significant correlation between Positive Symptom scores and pHVA levels was observed for non-responders. The BPRS Total and Negative Symptom scores did not correlate with pHVA for all patients, responders or non-responders at any time. The percent decrease in the BPRS Positive Symptom scores from baseline at 6 weeks following clozapine treatment correlated significantly with pHVA levels in responders. These results suggest that pretreatment levels of pHVA can be used to predict relatively short-term changes in the positive symptoms of patients with schizophrenia receiving clozapine treatment, particularly for clozapine responders.

Improvement of schizophrenic symptoms and changes in plasma HVA concentrations, plasma anti-D2 and anti-5-HT2 receptor activities with clozapine

In order to investigate the biological mechanisms underlying the clinical efficacy of clozapine, 200 mg/day of clozapine was added to the drug regimens of 19 patients with chronic, anti-psychotic-resistant schizophrenia, and the plasma homovanillic acid (HVA), clozapine concentrations, anti-dopamine D2 and anti-serotonin 5-HT2 receptor activities were measured. After 28 days, six patients showed an improvement of more than 20% over baseline Brief Psychiatric Rating Scale (BPRS) scores. Mean plasma HVA concentrations and anti-D2 receptor activities did not change significantly in the entire group or in the six patients showing improvement. However, anti-5-HT2 receptor activities increased significantly in all 19 patients. Changes in BPRS scores did not correlate significantly with changes in plasma HVA or with changes in clozapine concentrations, or with anti-D2 and anti-5-HT2 receptor activities.

Gating of auditory P50 in schizophrenics: unique effects of clozapine

Schizophrenic patients have a deficit in the ability to filter sensory stimuli, which can be demonstrated in several psychophysiological paradigms. For example, most unmedicated schizophrenic subjects fail to decrement the P50 auditory evoked response to the second of paired stimuli, when the interstimulus interval is 500 msec. This sensory gating deficit persists in schizophrenics treated with typical antipsychotics, even if they show significant clinical improvement. When the interstimulus interval is 100 msec, most schizophrenics exhibit impaired gating while acutely ill, but normalize with treatment. Clozapine, the prototypic atypical antipsychotic medication, is clinically more effective than conventional neuroleptics in a significant proportion of schizophrenics refractory to other drug treatment. Nine schizophrenic subjects who were refractory to conventional neuroleptic treatment were studied while being treated with typical neuroleptics and then restudied after 1 month's treatment with clozapine. In the six clozapine responders, there was significant improvement of P50 gating at the 500 msec interval. At the 100 msec interval there was an inverse relationship between sensory gating of P50 and clozapine dose, independent of clinical response. Thus, although this can only be considered preliminary data because of the small number of subjects, it appears that clozapine, compared to typical neuroleptics, has distinct effects on P50 gating.

Idazoxan and response to typical neuroleptics in treatment-resistant schizophrenia. Comparison with the atypical neuroleptic, clozapine

BACKGROUND

We investigated whether antagonism of alpha 2 adrenergic receptors would augment treatment response in schizophrenia, by administering idazoxan, an alpha 2 antagonist drug, to treatment-resistant patients on typical neuroleptics.

METHOD

Seventeen hospitalised treatment-resistant patients with DSM-III-R schizophrenia or schizoaffective disorder were studied on typical neuroleptic treatment, on treatment with idazoxan plus typical neuroleptic, and after discontinuation of idazoxan, in fixed, non-random order, and under double-blind, placebo-controlled conditions.

RESULTS

The addition of idazoxan to fluphenazine treatment resulted in significant reductions of global psychosis and total, positive and negative symptoms on the Brief Psychiatric Rating Scale, compared to neuroleptic treatment alone. Symptom improvement significantly correlated with idazoxan-induced changes in indices of noradrenergic function. In a subgroup of patients, idazoxan plus typical neuroleptic treatment compared favourably with clozapine treatment, when both were compared to typical neuroleptic treatment alone.

CONCLUSIONS

The antagonism of alpha 2 receptors augmented therapeutic response to typical neuroleptic treatment in treatment-resistant patients with schizophrenia. This antagonism may contribute to clozapine's superior antipsychotic effects.

Mechanisms of action of atypical antipsychotic drugs: a critical analysis

Various criteria used to define atypical antipsychotic drugs include: 1) decrease, or absence, of the capacity to cause acute extrapyramidal motor side effects (acute EPSE) and tardive dyskinesia (TD); 2) increased therapeutic efficacy reflected by improvement in positive, negative, or cognitive symptoms; 3) and a decrease, or absence, of the capacity to increase prolactin levels. The pharmacologic basis of atypical antipsychotic drug activity has been the target of intensive study since the significance of clozapine was first appreciated. Three notions have been utilized conceptually to explain the distinction between atypical versus typical antipsychotic drugs: 1) dose-response separation between particular pharmacologic functions; 2) anatomic specificity of particular pharmacologic activities; 3) neurotransmitter receptor interactions and pharmacodynamics. These conceptual bases are not mutually exclusive, and the demonstration of limbic versus extrapyramidal motor functional selectivity is apparent within each arbitrary theoretical base. This review discusses salient distinctions predominantly between prototypic atypical and typical antipsychotic drugs such as clozapine and haloperidol, respectively. In addition, areas of common function between atypical and typical antipsychotic drug action may also be crucial to our identification of pathophysiological foci of the different dimensions of schizophrenia, including positive symptoms, negative symptoms, and neurocognitive deficits.

Effects of clozapine on CSF homovanillic acid in spasmodic torticollis

We studied the effect of the atypical neuroleptic clozapine (CLO) on homovanillic acid (HVA) in cerebrospinal fluid (CSF) in five patients with spasmocid torticollis. Lumbar puncture was performed before and on the seventh day of CLO treatment. Although an HVA elevation was to be expected because of the antidopaminergic action of CLO, statistical analysis failed to reveal any significant increase of HVA under CLO treatment. Thus significance of CSF HVA may be less important for the description of antidopaminergic action of neuroleptics than previously assumed.