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

Clozapine-Induced Cardiovascular Side Effects and Autonomic Dysfunction: A Systematic Review

Background: Clozapine is the antipsychotic of choice for treatment-resistant schizophrenia and has minimal risk for extrapyramidal symptoms. Therapeutic benefits, however, are accompanied by a myriad of cardiometabolic side-effects. The specific reasons for clozapine's high propensity to cause adverse cardiometabolic events remain unknown, but it is believed that autonomic dysfunction may play a role in many of these.

Objective: This systematic review summarizes the literature on autonomic dysfunction and related cardiovascular side effects associated with clozapine treatment.

Method: A search of the EMBASE, MEDLINE, and EBM Cochrane databases was conducted using the search terms antipsychotic agents, antipsychotic drug^*, antipsychotic^*, schizophrenia, schizophren^*, psychos^*, psychotic^*, mental ill^*, mental disorder^*, neuroleptic^*, cardiovascular^*, cardiovascular diseases, clozapine^*, clozaril^*, autonomic^*, sympathetic^*, catecholamine^*, norepinephrine, noradrenaline, epinephrine, adrenaline.

Results: The search yielded 37 studies that were reviewed, of which only 16 studies have used interventions to manage cardiovascular side effects. Side effects reported in the studies include myocarditis, orthostatic hypotension and tachycardia. These were attributed to sympathetic hyperactivity, decreased vagal contribution, blockade of cholinergic and adrenergic receptors, reduced heart rate variability and elevated catecholamines with clozapine use. Autonomic neuropathy was identified by monitoring blood pressure and heart rate changes in response to stimuli and by spectral analysis of heart rate variability. Metoprolol, lorazepam, atenolol, propranolol, amlodipine, vasopressin and norepinephrine infusion were used to treat tachycardia and fluctuations in blood pressure, yet results were limited to case reports.

Conclusion: The results indicate there is a lack of clinical studies investigating autonomic dysfunction and a limited use of interventions to manage cardiovascular side effects associated with clozapine. As there is often no alternative treatment for refractory schizophrenia, the current review highlights the need for better designed studies, use of autonomic tests for prevention of cardiovascular disease and development of novel interventions for clozapine-induced side effects.

Disruption of dopamine D1/D2 receptor complex is involved in the function of haloperidol in cardiac H9c2 cells

AIMS

Haloperidol is an antipsychotic agent and acts as dopamine D2 receptor (D2R) antagonist, as a prototypical ligand of sigma1 receptors (Sig1R) and it increases expression of type 1 IP₃ receptors (IP₃R1). However, precise mechanism of haloperidol action on cardiomyocytes through dopaminergic signaling was not described yet. This study investigated a role of dopamine receptors in haloperidol-induced increase in IP₃R1 and Sig1R, and compared physiological effect of melperone and haloperidol on basic heart parameters in rats.

MATERIALS AND METHODS

We used differentiated NG-108 cells and H9c2 cells. Gene expression, Western blot and immunofluorescence were used to evaluate haloperidol-induced differences; proximity ligation assay (PLA) and immunoprecipitation to determine interactions of D1/D2 receptors. To evaluate cardiac parameters, Wistar albino male rats were used.

KEY FINDINGS

We have shown that antagonism of D2R with either haloperidol or melperone results in upregulation of both, IP₃R1 and Sig1R, which is associated with increased D2R, but reduced D1R expression. Immunofluorescence, immunoprecipitation and PLA support formation of heteromeric D1/D2 complexes in H9c2 cells. Treatment with haloperidol (but not melperone) caused decrease in systolic and diastolic blood pressure and significant increase in heart rate.

SIGNIFICANCE

Because D1R/D2R complexes can engage Gq-like signaling in other experimental systems, these results are consistent with the possibility that disruption of D1R/D2R complex in H9c2 cells might cause a decrease in IP₃R1 activity, which in turn may account for the increase expression of IP₃R and Sig1R. D2R is probably not responsible for changes in cardiac parameters, since melperone did not have any effect.

Association of the Cholinergic Muscarinic M2 Receptor with Autonomic Nervous System Activity in Patients with Schizophrenia on High-Dose Antipsychotics

BACKGROUND

Patients with schizophrenia have abnormal autonomic nervous system (ANS) activity compared with the general population. One reason for this difference is the muscarinic affinity for antipsychotic drugs; therefore, single nucleotide polymorphisms (SNPs) of the muscarinic receptor gene influence this ANS dysfunction. This study sought to determine the effect of SNPs of the cholinergic muscarinic receptor (CHRM) gene on ANS activity in patients with schizophrenia receiving antipsychotic drugs.

METHODS

A total of 173 Japanese patients with schizophrenia were included in this study. Heart rate variability (HRV) was measured as an index of ANS activity. SNPs in CHRM1 (rs542269 and rs2075748), CHRM2 (rs324640, rs8191992, rs1824024, and rs7810473), and CHRM3 (rs3738435, rs4620530, and rs6429157) were genotyped using the TaqMan® method. Patients were grouped according to standard equivalent conversions of chlorpromazine (CP) into a high-CP group (HG; ≥1,000 mg) and a low-CP group (LG; <1,000 mg). ANS activity was compared between the groups. In addition, we compared the total, low-frequency (LF), high-frequency (HF), and LF/HF components of the patients' HRV, and the genotype of the SNPs in both the HG and LG groups. Bonferroni correction was applied for multiple comparisons, and the Bonferroni-corrected critical p value was <0.005.

RESULTS

The A allele of the CHRM2 rs8191992 polymorphism in HG was associated with decreased ANS activity.

CONCLUSION

Our results show reduced ANS activity in association with the CHRM2 rs8191992 polymorphism in patients with schizophrenia on high-dose antipsychotics. CHRM2 polymorphisms may play an important role in ANS activity in patients with schizophrenia.

Long-Term Haloperidol Treatment Prolongs QT Interval and Increases Expression of Sigma 1 and IP3 Receptors in Guinea Pig Hearts

Haloperidol is a neuroleptic drug used for a medication of various psychoses and deliria. Its administration is frequently accompanied by cardiovascular side effects, expressed as QT interval prolongation and occurrence of even lethal arrhythmias. Despite these side effects, haloperidol is still prescribed in Europe in clinical practice. Haloperidol binds to sigma receptors that are coupled with inositol 1,4,5-trisphosphate (IP3) receptors. Sigma receptors are expressed in various tissues, including heart muscle, and they modulate potassium channels. Together with IP3 receptors, sigma receptors are also involved in calcium handling in various tissues. Therefore, the present work aimed to study the effects of long-term haloperidol administration on the cardiac function. Haloperidol (2 mg/kg once a day) or vehiculum was administered by intraperitoneal injection to guinea pigs for 21 consecutive days. We measured the responsiveness of the hearts isolated from the haloperidol-treated animals to additional application of haloperidol. Expression of the sigma 1 receptor and IP3 receptors was studied by real time-PCR and immunohistochemical analyses. Haloperidol treatment caused the significant decrease in the relative heart rate and the prolongation of QT interval of the isolated hearts from the haloperidol-treated animals, compared to the hearts isolated from control animals. The expression of sigma 1 and IP3 type 1 and type 2 receptors was increased in both atria of the haloperidol-treated animals but not in ventricles. The modulation of sigma 1 and IP3 receptors may lead to altered calcium handling in cardiomyocytes and thus contribute to changed sensitivity of cardiac cells to arrhythmias.

Cardiovascular effects of antipsychotics

There is great concern over cardiovascular disease in the schizophrenic population owing to the high incidence of cardiovascular mortality. Increased cardiovascular mortality is related to lifestyle choices (e.g., smoking and sedentary lifestyle) and a high prevalence of comorbid medical conditions, including dyslipidemia, the metabolic syndrome and Type 2 diabetes. One factor that increases cardiovascular risk is the medications used to treat the core features of schizophrenia. Adverse cardiovascular effects of antipsychotic treatment have been recognized for many decades, especially tachycardia, orthostatic hypotension and rare instances of sudden death; but, since 2000, there has been a significant shift in the focus of risk perception. The older antipsychotic literature is replete with papers primarily concerned with the physiological consequences of muscarinic cholinergic antagonism, alpha(1)-adrenergic antagonism or receptors associated with cardiac conduction, but the current literature recognizes that, for most antipsychotic-exposed patients, the more significant cardiovascular burden of treatment is mediated by metabolic adverse effects such as weight gain, dyslipidemia and diabetes mellitus. The purpose of this review is to examine the cardiovascular risks of treatment with antipsychotic medications, elucidating relevant mechanisms and differences between various agents, especially for metabolic adverse effects seen with atypical antipsychotics.

The Deceleration Capacity - a New Measure of Heart Rate Variability Evaluated in Patients With Schizophrenia and Antipsychotic Treatment

Background

Schizophrenia is associated with increased cardiac mortality. A disturbed autonomic modulation of heart rate (HR) has been described in patients with schizophrenia in whom antipsychotic medication may represent an additional cardiac risk. The novel measure deceleration capacity (DC) of heart rate predicts cardiac mortality in patients with cardiovascular illnesses. The aim of the present paper was to calculate DC in patients with schizophrenia and to compare this measure with established parameters of heart rate variability (HRV).

Methods

HRV and DC were calculated in 24-hour electrocardiogram (ECG) recordings of 20 unmedicated, 40 medicated patients with schizophrenia and 40 controls. As activity has a major influence on HRV, 4-hour periods of “sleep-” and “wake-” ECG were evaluated as additional parameters. Actigraphy was used to ensure comparable levels of activity in patients and controls.

Results

The DC as well as the other established HRV measures were not significantly different comparing unmedicated patients with schizophrenia to healthy controls. However, medicated patients showed a significant reduction of DC calculated from ECG recordings during 4 hour over night periods.

Conclusion

Calculation of DC might contribute to a better monitoring and identification of an increased risk of cardiac mortality in patients with schizophrenia undergoing antipsychotic treatment.

How is electrocardiogram influenced by electroconvulsive therapy in males and females?

OBJECTIVES

We aimed to investigate and compare the P duration and P dispersion (Pd) between male and female patients with a primary diagnosis of chronic schizophrenia disorder before and after the electroconvulsive therapy (ECT) period.

METHODS

We obtained electrocardiograms of 50 healthy young volunteers which included 25 female (group F, n = 25) and 25 male patients (group M, n = 25). We measured minimum and maximum P wave durations (Pmin, Pmax) and Pd in milliseconds. Electrocardiography was performed before electroconvulsive therapy (ECT) and immediately after the ECT period after awakening. A 12-lead surface electrocardiogram was obtained from each subject in the supine position.

RESULTS

The post-ECT P duration was significantly longer than the pre-ECT P duration in groups F and M (P = 0.01 and P = 0.008, respectively). The post-ECT Pd was significantly longer than the pre-ECT Pd in groups F and M (P = 0.0001 in both groups). A higher correlation (r) in group M was observed between the pre-ECT Pd and post-ECT P duration than in group F (r = 0.538, P = 006 in group M; r = 0.349, P = 08 in group F). There was no significant difference between the groups regarding hemodynamics.

CONCLUSIONS

Electroconvulsive therapy in both sexes may influence atrial conduction as evidenced by the significantly prolonged Pmax and Pd in patients with a primary diagnosis of schizophrenia disorder.

Heart rate variability in bipolar mania and schizophrenia

BACKGROUND

Autonomic nervous system (ANS) dysfunction and reduced heart rate variability (HRV) have been reported in a wide variety of psychiatric disorders, but have not been well characterized in bipolar mania. We recorded cardiac activity and assessed HRV in acutely hospitalized manic bipolar (BD) and schizophrenia (SCZ) patients compared to age- and gender-matched healthy comparison (HC) subjects.

METHOD

HRV was assessed using time domain, frequency domain, and nonlinear analyses in 23 manic BD, 14 SCZ, and 23 HC subjects during a 5min rest period. Psychiatric symptoms were assessed by administration of the Brief Psychiatric Rating Scale (BPRS) and the Young Mania Rating Scale (YMRS).

RESULTS

Manic BD patients demonstrated a significant reduction in HRV, parasympathetic activity, and cardiac entropy compared to HC subjects, while SCZ patients demonstrated a similar, but non-significant, trend towards lower HRV and entropy. Reduction in parasympathetic tone was significantly correlated with higher YMRS scores and the unusual thought content subscale on the BPRS. Decreased entropy was associated with increased aggression and diminished personal hygiene on the YMRS scale.

CONCLUSION

Cardiac function in manic BD individuals is characterized by decreased HRV, reduced vagal tone, and a decline in heart rate complexity as assessed by linear and nonlinear methods of analysis. Autonomic dysregulation is associated with more severe psychiatric symptoms, suggesting HRV dysfunction in this disorder may be dependent on the phase of the illness.

Cardiovascular variability during treatment with haloperidol, olanzapine or risperidone in recent-onset schizophrenia

This study aimed to investigate the effects of treatment with haloperidol, olanzapine and risperidone on cardiovascular variability in patients with recent-onset schizophrenia by means of spectral analysis. Unmedicated patients (n = 18) had a higher mean heart rate and a tendency for a lower high-frequency power of heart rate variability than healthy control subjects (n = 57), indicating a decreased cardiac vagal control in unmedicated patients with schizophrenia. Patients treated with haloperidol (n = 10) showed significantly lower low-frequency power of heart rate and systolic blood pressure variability compared with olanzapine-treated patients, suggesting that haloperidol attenuated sympathetic functioning. On the contrary, olanzapine-treated patients (n = 10) showed the highest power in the low-frequency range of heart rate and systolic blood pressure variability, suggesting an increased sympathetic cardiac functioning. No significant effects of risperidone (n = 13) were found. None of the antipsychotic agents differed in their parasympathetic cardiovascular effects. We conclude that young, unmedicated patients with schizophrenia differed from controls in their parasympathetic functioning, but the antipsychotic agents haloperidol, risperidone and olanzapine induced only minor cardiovascular side effects.

Electrocardiographical P wave changes after electroconvulsive therapy in patients with schizophrenia: a preliminary study

OBJECTIVE

Cardiac ventricular conduction has been studied in patients with schizophrenia who have undergone electroconvulsive therapies while they were drug-naive or drug-free or on drug regimens; however, atrial conduction has not been studied in this setting. We aimed to measure atrial and ventricular conduction changes in hospitalized patients with schizophrenia after convulsive therapy.

METHODS

Fifteen people with schizophrenia and 15 healthy people enrolled in the study. The participants were assessed for fasting blood glucose and electrolyte levels before the study. All patients were receiving atypical antipsychotics. The electrocardiography records were obtained before the first convulsive therapy and after the third session.

RESULTS

The baseline P minimum duration in the patient group was significantly smaller than healthy controls. There was a significant increase in patients' P maximum duration after the third convulsive therapy session (P < 0.05). The differences in P Wave Dispersion, QTc, and QT Dispersion between baseline and after the third session in patients were not statistically significant (P > 0.05).

CONCLUSIONS

The lower P wave duration minimum may be related to autonomic nervous system dysregulation in schizophrenia because an acute episode of the illness and/or antipsychotic drugs. In addition, we propose that electroconvulsive therapy alone or in combination with atypical antipsychotics may influence atrial conduction as evidenced by the significantly prolonged P wave maximum.

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.

The Phenothiazine Drugs Inhibit hERG Potassium Channels

Cardiovascular adverse effects from phenothiazine drugs are common. The most serious consequences of treatment, arrhythmias and sudden death, are probably rare and most likely to be caused primarily by blockade of cardiac potassium channels such as the human ether-a-go-go-related gene (hERG) channel, which plays a central role in arrhythmogenesis. This phenomenon has been previously reported to occur with a few phenothiazine drugs. However, phenothiazine drugs are composed of pharmacologically and structurally diverse groups. The effects of many of the phenothiazine drugs on hERG channels expressed in mammalian cell lines remain unknown. Therefore, we investigated the effects of four distinct phenothiazine drugs (thioridazine, chlorpromazine, trifluoperazine, and perphenazine) on hERG channel expressed in chinese hamster ovary (CHO) cells. HERG channels were expressed in CHO cells, and ion currents were measured using the patch-clamp technique. Thioridazine, perphenazine, trifluoperazine, and chlorpromazine blocked hERG potassium channels with the following IC(50) values: IC(50) values were 224 +/- 42 nM for thioridazine, 1003 +/- 71 nM for perphenazine, 1406 +/- 124 nM for trifluoperazine, and 1561 +/- 281 nM for chloropromazine. Inhibition of hERG channels by thioridazine was characterized by significant changes in voltage dependence, the value of V(1/2), the half-maximal activation potential, and shift into negative potential, that is, the amount of block was greater at more positive potential. No significant changes were noted in other drugs.

Arousability in schizophrenia: relationship to emotional and physiological reactivity and symptom severity

OBJECTIVE

Socioenvironmental stressors have been linked with increased symptom severity and relapse in those with schizophrenia. However, little is known about how individual differences in stress reactivity may contribute to these outcomes.

METHOD

This study examined the association between the temperament characteristic of arousability and changes in negative affect and cardiovascular activity during a challenge task in 58 in-patients with diagnosis of schizophrenia and 21 controls.

RESULTS

In the patient group, levels of arousability were significantly associated with increases in negative affect in response to the task and greater severity of affective symptoms. Levels of arousability were associated with decreased heart rate during the challenge task in our patient group.

CONCLUSION

These findings suggest that greater attention be given to individual differences, such as temperament and personality characteristics, and their role in the experience of stressors, including emotional and physiological response, as well as symptom development.

Heart rate variability during sleep in patients with schizophrenia treated with olanzapine

Cardiac adverse events in patients treated with atypical antipsychotics have gained increasing interest in recent years. In the present study, heart rate variability (HRV), which is a sensitive parameter reflecting central autonomic cardiac control, was investigated during treatment with olanzapine. Ten physically healthy male patients with schizophrenia, who displayed predominantly negative symptoms, were studied in the sleep laboratory under drug-free baseline conditions and after 4 weeks of olanzapine medication. HRV was assessed during different sleep stages both in the time and frequency domains. Only slight changes in HRV were shown during treatment, and appeared to be independent of sleep stages. Spectral analysis indicated a slight shift of the sympathovagal balance in favour of the sympathetic tone, which was consistent with an elevation of heart rate in the time domain; total HRV was not altered. These changes are in accordance with olanzapine's receptor profile exerting anticholinergic and anti-adrenergic properties. In conclusion, taken together with findings from previous studies demonstrating that olanzapine does not cause clinically significant changes of the QTc interval, the present results are consistent with the known cardiac safety profile of olanzapine.

Alterations in QT dispersion in medicated schizophrenia patients following electroconvulsive therapy

QT dispersion (QTd) is a measure of interlead variations of the surface 12-lead electrocardiogram (ECG). Increased QTd, found in various cardiac diseases, reflects cardiac instability and is associated with increased risk for cardiac death. Research suggests a link between antipsychotics, ECG abnormalities (QT prolongation) and increased sudden cardiac mortality rates. However, QTd analysis has been scarcely investigated in schizophrenia patients. We calculated QTd in 20 medicated psychotic inpatients with schizophrenia, before and 3 days after electroconvulsive therapy (ECT), concomitantly with Brief Psychiatric Rating Scale (BPRS) assessment. QT interval and the rate-corrected QT (QTc) were abnormally prolonged before ECT. However, although QT was significantly shortened, QTc showed only a marginal decrease after ECT. QTd, the rate-corrected QTd, as well as BPRS, showed a significant decrease after ECT. Further large-scale studies are warranted to determine if QTd can serve as a marker for response to ECT, and if it is a risk factor for sudden cardiac death in schizophrenia patients.

Heart rate variability in acute psychosis

Heart rate variability (HRV) provides reliable tools to assess the integrity and reactivity of autonomic nervous function. Our aim was to examine HRV in the resting condition and during different mental loads in acute psychosis compared to healthy controls. HRV was measured in 17 first-episode drug-naive patients with psychosis and 21 healthy controls during oddball tasks and while performing the Wisconsin Card Sorting Test. A discrete event series was constructed by an adaptive QRS detector algorithm and power spectrum estimation was carried out. The RMSSD (representing interval differences of successive heartbeats) and the amount of high frequency (HF) power were significantly reduced in patients. Moreover, the patients' HRV remained unaltered during the tasks, whereas in controls the HRV diminished with increasing mental load of the task. Patients with psychosis displayed less short-term HR reactivity than healthy controls. They also failed to adapt HRV according to the task-connected strain. Acute psychosis is characterized by a limited capacity to respond to external demands at the level of autonomic nervous system.

The potential cardiotoxicity of antipsychotic drugs as assessed by heart rate variability

Most antipsychotic drugs have cardiac effects as a consequence of their pharmacological actions. Recently, thioridazine has been subjected to a restricted indications notice and sertindole had its license withdrawn because of concerns about their potential cardiotoxicity. In the development of new atypical agents, heart-rate corrected QT effects are evaluated but it is unclear how predictive these are of clinically significant cardiotoxicity or sudden death. Heart rate variability (HRV) is a potential index of cardiotoxicity which has been found to be decreased following antidepressants and clozapine. We studied acute HRV changes following antipsychotic agents. Sixteen healthy male volunteers received risperidone (4 mg), olanzapine (10 mg), thioridazine (50 mg) or placebo in a randomized cross-over design. Subjective effects and psychomotor function were assayed at 2 h and both linear (summary statistics) and non-linear (scatterplot) measures of HRV were evaluated by continuous electrocardiogram recording over 10 h. Differential effects of single doses of the three antipsychotic drugs on HRV were found, and these were independent of their sedative effects. Olanzapine increased, and thioridazine decreased HRV, while risperidone had no effect. HRV is sensitive to the acute effects of antipsychotics. It may prove to be a reliable index of their potential for cardiotoxicity. Further studies in both healthy volunteers and patients on antipsychotic medication will be valuable.

Schizophrenic patients who develop postoperative confusion have an increased norepinephrine and cortisol response to surgery

The purpose of this study was to investigate the relationship between postoperative confusion and the plasma norepinephrine (NE), adrenocorticotropin (ACTH) or cortisol response to surgery in schizophrenic patients. We studied 50 schizophrenic patients and 35 control patients who underwent orthopedic surgery and perioperatively measured plasma NE, ACTH and cortisol levels. Postoperative confusion during 72 h after the end of the operation occurred in 14 of 50 schizophrenic patients (28%) and in 2 of 35 control patients (6%). Plasma NE levels 15 min after skin incision, the next day, the second day and the third day after operation in schizophrenic patients with postoperative confusion (668.0 +/- 59.2, 522.0 +/- 96.5, 463.2 +/- 71.2 and 398.9 +/- 56.2 pg/ml, respectively) were significantly higher than those in schizophrenic patients without confusion (524.1 +/- 62.6, 342.4 +/- 38.6, 311.2 +/- 58.3 and 314.1 +/- 77.1 pg/ml, respectively). Plasma cortisol levels 15 min after the skin incision and the next and second days after operation in schizophrenic patients with postoperative confusion (23.6 +/- 3.2, 21.1 +/- 4.3 and 19.9 +/- 4.4 microg/dl, respectively) were significantly higher than those in schizophrenic patients without confusion (15.2 +/- 4.5, 14.3 +/- 5.1 and 13.8 +/- 3.8 microg/dl, respectively). In conclusion, the occurrence of postoperative confusion in schizophrenic patients is associated with an increase in plasma norepinephrine and cortisol levels during and after surgery.

Effects of newer atypical antipsychotics on autonomic neurocardiac function: a comparison between amisulpride, olanzapine, sertindole, and clozapine

As part of a prospective clinical study investigating the effects of atypical neuroleptics on autonomic neurocardiac function (ANF), serial standardized recordings of conventional electrocardiograms and computer-calculated measurements of 5-minute resting heart rate variability (HRV) were obtained from 51 medication-free inpatients with schizophrenia (DSM-III-R-diagnosed) before and after an average of 14.1 days of treatment with amisulpride 400 mg/day (N = 12), olanzapine 20 mg/day (N = 13), sertindole 12 mg/day (N = 13), or clozapine 100 mg/day (N = 13). Reference values for the HRV data were obtained from a large group of well-matched healthy controls (N = 70). The most important findings were the following: (1) clozapine, olanzapine, and sertindole all prolonged mean frequency-corrected QTc times, which, in the case of sertindole, proved to be significant (Wilcoxon test p <0.05); (2) sertindole and clozapine significantly increased the mean resting heart rate; and (3) only clozapine significantly reduced the parasympathetic resting tone. The results of the HRV studies are discussed considering the in vitro receptor profiles of the atypical neuroleptics under study. Potential implications for the cardiac safety and tolerance of these drugs are also discussed.

Cardiovascular adverse effects of antipsychotic drugs

Minor cardiovascular adverse effects from antipsychotic drugs are extremely common. They include effects such as postural hypotension and tachycardia due to anticholinergic or alpha1-adrenoceptor blockade, and may occur in the majority of patients at therapeutic dosages. There are a number of pharmacological effects that are of uncertain clinical significance, such as blockade of calmodulin, sodium and calcium channels and alpha2-adrenoceptors in the central nervous system. The most serious consequences of treatment, arrhythmias and sudden death, are probably uncommon and are most likely to be caused primarily by blockade of cardiac potassium channels such as HERG. Incomplete evidence suggests that arrhythmias and sudden death are a particular problem with certain drugs (thioridazine and droperidol), high risk populations (elderly, pre-existing cardiovascular disease, inherited disorders of cardiac ion channels or of antipsychotic drug metabolism) or people taking interacting drugs (such as drugs that prolong the QT interval, e.g. tricyclic antidepressants, drugs that inhibit antipsychotic drug metabolism, or diuretics). Clozapine may be unique in also causing death from myocarditis and cardiomyopathy. Much further research is required to more clearly identify high risk drugs and the populations that are at risk of sudden death, as well as the mechanisms involved and the extent of the risk.

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

Alcoholism, peripheral neuropathy (PNP) and cardiovascular autonomic neuropathy (CAN)

In contrast to diabetic autonomic neuropathy, cardiovascular autonomic neuropathy (CAN) in long-term alcoholics has been studied rarely. Using both standardized bedside tests and computer-assisted analysis of heart rate variability (HRV), we prospectively compared autonomic neurocardial function between 35 strictly selected, detoxified alcoholics (DSM-III-R), and 80 well matched healthy controls. Evidence for a potential CAN was found in 25.7% of all the alcoholics studied and in 41% of those with clinically manifest PNP (n=22). Overall, our results demonstrated a significant association between the presence of a CAN and peripheral neuropathy (PNP) amongst chronic alcoholics (chi-square test P<0.05); there was no evidence of a CAN in any of the alcoholics without a clinically manifest PNP. The CAN was characterized by a dissociated appearance of parasympathetic and sympathetic disorders. Our findings provide reason to suspect that the total lifetime dose of alcohol and the duration of alcohol dependence are the most important factors contributing to the pathogenesis of both PNP and sympathetic dysfunction. As is the case with diabetics, computer-assisted measurements of HRV including spectral analysis appear to be far superior to conventional bedside tests for detecting evidence of cardiovagal dysfunction in long-term alcoholics.