Prolongation of QT interval in isolated feline hearts by antipsychotic drugs

Assessment of Risperidone Toxicity in Zebrafish (Danio rerio) Embryos

Risperidone is an antipsychotic medication used in the treatment of conditions like autism and schizophrenia. The goal of the current study was to examine the effects of risperidone in zebrafish embryos ( Danio rerio ) with regard to survival, development, and cardiac and neural systems. The results showed that concentrations above 100 μM were associated with deaths, teratogenic effects, and cardiotoxic and neurotoxic effects. The findings support the utility of zebrafish for toxicological screening studies.

The atypic antipsychotic clozapine inhibits multiple cardiac ion channels

Clozapine is an atypical neuroleptic used to manage treatment-resistant schizophrenia which is known to inhibit cardiac hERG/K_V11.1 potassium channels, a pharmacological property associated with increased risk of potentially fatal Torsades de Pointes (TdP) and sudden cardiac death (SCD). Yet, the long-standing clinical practice of clozapine does not show a consistent association with increased incidence of TdP, although SCD is considerably higher among schizophrenic patients than in the general population. Here, we have established the inhibitory profile of clozapine at the seven cardiac ion currents proposed by the ongoing comprehensive in vitro pro-arrhythmia (CiPA) initiative to better predict new drug cardio-safety risk. We found that clozapine inhibited all CiPA currents tested with the following rank order of potency: K_V11.1 > Na_V1.5 _{(late current)} ≈ Ca_V1.2 ≈ Na_V1.5 _{(peak current)} ≈ K_V7.1 > K_V4.3 > K_ir2.1 _{(outward current)}. Half-maximal inhibitory concentrations (IC₅₀) at the repolarizing K_V11.1 and K_V7.1 channels, and at the depolarizing Ca_V1.2 and Na_V1.5 channels fell within a narrow half-log 3-10 µM concentration range, suggesting that mutual compensation could explain the satisfactory arrhythmogenic cardio-safety profile of clozapine. Although the IC₅₀ values determined herein using an automated patch-clamp (APC) technique are at the higher end of clozapine plasmatic concentrations at target therapeutic doses, this effective antipsychotic appears prone to distribute preferentially into the cardiac tissue, which supports the clinical relevance of our in vitro pharmacological findings.

Oxytocin exerts harmful cardiac repolarization prolonging effects in drug-induced LQTS

Background

Oxytocin is used therapeutically in psychiatric patients. Many of these also receive anti-depressant or anti-psychotic drugs causing acquired long-QT-syndrome (LQTS) by blocking HERG/I_Kr. We previously identified an oxytocin-induced QT-prolongation in LQT2 rabbits, indicating potential harmful effects of combined therapy. We thus aimed to analyze the effects of dual therapy with oxytocin and fluoxetine/risperidone on cardiac repolarization.

Methods

Effects of risperidone, fluoxetine and oxytocin on QT/QTc, short-term variability (STV) of QT, and APD were assessed in rabbits using in vivo ECG and ex vivo monophasic AP recordings in Langendorff-perfused hearts. Underlying mechanisms were assessed using patch clamp in isolated cardiomyocytes.

Results

Oxytocin, fluoxetine and risperidone prolonged QTc and APD in whole hearts. The combination of fluoxetine + oxytocin resulted in further QTc- and APD-prolongation, risperidone + oxytocin tended to increase QTc and APD compared to monotherapy. Temporal QT instability, STV_QTc was increased by oxytocin, fluoxetine / fluoxetine + oxytocin and risperidone / risperidone + oxytocin. Similar APD-prolonging effects were confirmed in isolated cardiomyocytes due to differential effects of the compounds on repolarizing ion currents: Oxytocin reduced I_Ks, fluoxetine and risperidone reduced I_Kr, resulting in additive effects on I_Ktotal-tail. In addition, oxytocin reduced I_K1, further reducing the repolarization reserve.

Conclusion

Oxytocin, risperidone and fluoxetine prolong QTc / APD. Combined treatment further prolongs QTc/APD due to differential effects on I_Ks and I_K1 (block by oxytocin) and I_Kr (block by risperidone and fluoxetine), leading to pronounced impairment of repolarization reserve. Oxytocin should be used with caution in patients in the context of acquired LQTS.

Mapping the Knowledge of Antipsychotics-Induced Sudden Cardiac Death: A Scientometric Analysis in CiteSpace and VOSviewer

The drugs on the market for schizophrenia are first-generation and second-generation antipsychotics. Some of the first-generation drugs have more side effects than the other drugs, so they are gradually no longer being applied clinically. Years of research have shown that the risk of sudden cardiac death in psychotic patients is associated with drug use, and antipsychotic drugs have certain cardiotoxicity and can induce arrhythmias. The mechanism of antipsychotic-induced sudden cardiac death is complicated. Highly cited papers are among the most commonly used indicators for measuring scientific excellence. This article presents a high-level analysis of highly cited papers using Web of Science core collection databases, scientometrics methods, and thematic clusters. Temporal dynamics of focus topics are identified using a collaborative network (author, institution, thematic clusters, and temporal dynamics of focus topics are identified), keyword co-occurrence analysis, co-citation clustering, and keyword evolution. The primary purpose of this study is to discuss the visual results, summarize the research progress, and predict the future research trends by bibliometric methods of CiteSpace and VOSviewer. This study showed that a research hotspot is that the mechanisms of cardiotoxicity, the safety monitoring, and the assessment of the risk-benefit during clinical use of some newer antipsychotics, clozapine and olanzapine. We discussed relevant key articles briefly and provided ideas for future research directions for more researchers to conduct related research.

Safety evaluation of the interchangeable use of robenacoxib in commercially-available tablets and solution for injection in cats

Background

Robenacoxib (Onsior™) is a non-steroidal anti-inflammatory drug developed for canine and feline use for the control of pain and inflammation. It is available as both tablets and solution for injection.

The objective of this study was to evaluate the safety of the interchangeable use of commercially available robenacoxib formulations when administered to cats orally using 6 mg tablets and subcutaneously using a solution for injection containing 20 mg/mL. Thirty-four naïve healthy 4-month old cats were enrolled in this 37-day study and were randomized to four groups (three robenacoxib and one control). One robenacoxib group received the maximum recommended dose (MRD) rate of each formulation, while the other two received two and three times this dose rate. The cats underwent three 10-day treatment cycles comprised of seven days of once daily oral administration followed by three days of subcutaneous administration. The third cycle was followed by an additional seven days of oral treatment. The control group received oral empty gelatin capsules or subcutaneous saline injections. Assessment of safety was based on general health observations, clinical observations, physical, ophthalmic, electrocardiographic and neurological examinations, clinical pathology evaluations, food consumption, body weight, and macroscopic and microscopic examinations. Blood samples were collected for toxicokinetic evaluation.

Results

Blood concentrations of robenacoxib confirmed systemic exposure of all treated cats. All cats were in good health through study termination and there were no serious adverse events during the study. There were no changes in body weight, food consumption, ophthalmic, physical or neurological examinations during the study. Treatment-related abnormalities were of low occurrence at all doses and included injection site changes (transient edema with minimal or mild, subacute/chronic inflammation histologically) and prolongation of the QT interval. These findings were consistent with previously observed findings in studies with robenacoxib administered separately orally or subcutaneously in cats. Thus, there were no adverse effects that could be attributed specifically to the interchangeable use of oral and injectable robenacoxib.

Conclusions

This 37-day laboratory study supports the safety of interchanging robenacoxib injection at a daily dose of 2 mg/kg with robenacoxib tablets at a daily dose of 1 mg/kg, or vice versa.

Haloperidol Induced Sudden Cardiac Arrest-Report of a Very Rare Case and Review of Literature

Haloperidol is a typical antipsychotic drug. This drug is still widely used in emergency medicine, psychiatry, and general medicine departments. It is mostly used for acute confusional state, psychotic disorders, agitation, delirium, and aggressive behaviour. Overdose of haloperidol can cause sudden deaths. Cardiopulmonary arrest related to use of haloperidol had been reported in literature as case reports but are very few. No such cases have been reported in India till now. We report a case of cardiac arrest due to the use of haloperidol.

Exploring mechanisms of increased cardiovascular disease risk with antipsychotic medications: Risperidone alters the cardiac proteomic signature in mice

Atypical antipsychotic (AA) medications including risperidone (RIS) and olanzapine (OLAN) are FDA approved for the treatment of psychiatric disorders including schizophrenia, bipolar disorder and depression. Clinical side effects of AA medications include obesity, insulin resistance, dyslipidemia, hypertension and increased cardiovascular disease risk. Despite the known pharmacology of these AA medications, the mechanisms contributing to adverse metabolic side-effects are not well understood. To evaluate drug-associated effects on the heart, we assessed changes in the cardiac proteomic signature in mice administered for 4 weeks with clinically relevant exposure of RIS or OLAN. Using proteomic and gene enrichment analysis, we identified differentially expressed (DE) proteins in both RIS- and OLAN-treated mouse hearts (p < 0.05), including proteins comprising mitochondrial respiratory complex I and pathways involved in mitochondrial function and oxidative phosphorylation. A subset of DE proteins identified were further validated by both western blotting and quantitative real-time PCR. Histological evaluation of hearts indicated that AA-associated aberrant cardiac gene expression occurs prior to the onset of gross pathomorphological changes. Additionally, RIS treatment altered cardiac mitochondrial oxygen consumption and whole body energy expenditure. Our study provides insight into the mechanisms underlying increased patient risk for adverse cardiac outcomes with chronic treatment of AA medications.

Sudden cardiac death and antipsychotics. Part 1: Risk factors and mechanisms

Mortality from causes other than suicide is higher than expected in schizophrenia. Cardiovascular causes are most common, accounting for the majority of the 5% of sudden and unexpected deaths. Most cases have no clear explanation on post-mortem examination (‘sudden unexplained deaths’) and are thought to result from fatal arrhythmias. Prospective studies show that people with prolongation of the QT interval beyond 500 ms are at increased risk of serious arrhythmias such as ventricular tachycardia and torsade de pointes. In about 1 in 10 cases, the torsade is fatal. Most antipsychotics prolong the QTc interval in overdose but some prolong it even at therapeutic doses. Droperidol, sertindole and ziprasidone extend the QT interval by an average of 15–35 ms; quetiapine, haloperidol and olanzapine by 5 ms, to 15 ms. There is only an approximate relationship between QT prolongation and risk of sudden death, and the risk related to antipsychotics is thought to increase in people with pre-existing cardiac disease, those taking multiple QT-acting drugs and those taking antipsychotics at high dose for long periods. There is little evidence of an association with route of administration. More data are required to clarify to what extent people with mental health difficulties who die suddenly have pre-existing cardiac disease.

BPC 157 counteracts QTc prolongation induced by haloperidol, fluphenazine, clozapine, olanzapine, quetiapine, sulpiride, and metoclopramide in rats

AIM

Commonly, neuroleptics and prokinetics induce a prolonged QTc interval. In this study, stable gastric pentadecapeptide BPC 157 counteracts the prolongation of the QTc interval in Wistar rats that underwent daily administration of dopamine neuroleptics or prokinetics. Previously, in rats and mice, BPC 157 counteracted neuroleptic-induced catalepsy and gastric ulcers.

MAIN METHODS

To counteract neuroleptic- or prokinetic-induced prolongation of the QTc interval, rats were given a BPC 157 regimen once daily over seven days (10μg, 10ng/kg ip) immediately after each administrations of haloperidol (0.625, 6.25, 12.5, and 25.0mg/kg ip), fluphenazine (0.5, 5.0mg/kg ip), clozapine (1.0, 10.0mg/kg ip), quetiapine (1.0, 10.0mg/kg ip), sulpiride (1.6, 16.0mg/kg ip), metoclopramide (2.5, 25.0mg/kg ip) or (1.0, 10.0mg/kg ip). Controls simultaneously received saline (5ml/kg ip). To assess the ECG presentation before and after neuroleptic/prokinetic medication, the assessment was at 1, 2, 3, 4, 5, 10, 15, 20 and 30min (first administration) as well as at 30min, 60min and 24h (first administration and subsequent administrations) and the ECG recording started prior to drug administration.

KEY FINDINGS

Since very early, a prolonged QTc interval has been continually noted with haloperidol, fluphenazine, clozapine, olanzapine, quetiapine, sulpiride, and metoclopramide in rats as a central common effect not seen with domperidone. Consistent counteraction appears with the stable gastric pentadecapeptide BPC 157. Thus, BPC 157 rapidly and permanently counteracts the QTc prolongation induced by neuroleptics and prokinetics.

SIGNIFICANCE

Pentadecapeptide BPC 157 is suited for counteracting a prolonged QT interval.

Drug-induced fatal arrhythmias: Acquired long QT and Brugada syndromes

Since the early 1990s, the concept of primary "inherited" arrhythmia syndromes or ion channelopathies has evolved rapidly as a result of revolutionary progresses made in molecular genetics. Alterations in genes coding for membrane proteins such as ion channels or their associated proteins responsible for the generation of cardiac action potentials (AP) have been shown to cause specific malfunctions which eventually lead to cardiac arrhythmias. These arrhythmic disorders include congenital long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, short QT syndrome, progressive cardiac conduction disease, etc. Among these, long QT and Brugada syndromes are the most extensively studied, and drugs cause a phenocopy of these two diseases. To date, more than 10 different genes have been reported to be responsible for each syndrome. More recently, it was recognized that long QT syndrome can be latent, even in the presence of an unequivocally pathogenic mutation (silent mutation carrier). Co-existence of other pathological conditions in these silent mutation carriers may trigger a malignant form of ventricular arrhythmia, the so called torsade de pointes (TdP) that is most commonly brought about by drugs. In analogy to the drug-induced long QT syndrome, Brugada type 1 ECG can also be induced or unmasked by a wide variety of drugs and pathological conditions; so physicians may encounter patients with a latent form of Brugada syndrome. Of particular note, Brugada syndrome is frequently associated with atrial fibrillation whose therapeutic agents such as Vaughan Williams class IC drugs can unmask the dormant and asymptomatic Brugada syndrome. This review describes two types of drug-induced arrhythmias: the long QT and Brugada syndromes.

Comparative cardiovascular safety of risperidone and olanzapine, based on electrocardiographic parameters and blood pressure: a prospective open label observational study

Objective:

To assess the cardiovascular safety of two commonly prescribed atypical antipsychotics risperidone (RSP) and olanzapine (OZP) in schizophrenic patients, using electrocardiography (ECG) and Blood Pressure (BP).

Materials and Methods:

This was a 10-week prospective open label, observational study, carried out in a newly diagnosed 64 schizophrenic patients receiving either RSP or OZP. RSP (n = 32) was started with dose of 2 mg/day and increased to 4 mg/day after 2 weeks, whereas OZP (n = 32) was started at a dose of 5 mg/day and was increased to 10 mg/day after 2 weeks. Heart rate (HR), ECG parameters (PR, RR, QRS, QT intervals and QTc and QTd) and BP (systolic and diastolic in supine and standing position) were recorded at baseline (before drug therapy)) and during follow-up visits at 2(I), 6(II) and 10(III) weeks.

Results:

In the RSP group, at II and III follow-ups, a significant increase in the HR (P = 0.018, P = 0.011 respectively) as well as in QTc (P = 0.025, P = 0.015, respectively) was observed when compared to the basal values. In the OZP group, diastolic BP was significantly decreased in standing position at II and III follow-ups (P = 0.045 and P = 0.024, respectively) compared to the basal values. When the two groups were compared with each other, no significant differences were observed in the changes of HR, PR, QRS, QT, RR, QT, QTd and SBP (supine and standing position); and DBP (supine position). However, DBP in standing position showed a significant decrease in the OZP group at II and III follow-up (P = 0.036 and P = 0.016, respectively) compared to the RSP group.

Conclusions:

Patients treated with OZP are at higher risk to develop postural hypotension as compared with RSP; hence RSP could be better tolerated by patients taking antihypertensive drugs as compared with OZP whereas OZP would have a safer cardiac profile.

Efficacy and safety of sertindole in schizophrenia: a clinical review

Sertindole is an atypical antipsychotic reintroduced into the European market in 2005 after a reevaluation of its risks and benefits, under the agreement that close electrocardiographic screening would be conducted. It has a high affinity for dopamine D2, serotonin 5-HT2A and 5-HT2C, and α1 adrenergic receptors. Moreover, sertindole shows modest affinity for H1-histaminergic and muscarinic receptors. The pharmacological properties, clinical efficacy, safety, and tolerability of sertindole are covered in this article based on a literature review from 1990 to 2014. Given current available findings, sertindole is at least effective as haloperidol, risperidone, and olanzapine on schizophrenia symptoms. Regarding its efficacy on cognitive symptoms, sertindole effect is supported by both preclinical and clinical studies versus haloperidol and olanzapine; however, its role on cognition needs further clarification. Concerning safety and tolerability issues, sertindole is characterized by a low potential to cause sedation and extrapyramidal symptoms, and by an acceptable metabolic profile; nevertheless, cardiac safety remains a major concern, and the electrocardiographic monitoring should be carried out during treatment to substantially reduce cardiovascular risk. In conclusion, although it has an equivalent profile compared to other antipsychotic drugs, sertindole actually remains a second-line choice for schizophrenic patients intolerant to at least one other antipsychotic agent.

Intramuscular Haloperidol or Lorazepam and QT Intervals in Schizophrenia

The objective of this study was to estimate the effects of intramuscular haloperidol and lorazepam on the QT interval in volunteers with schizophrenia. Intramuscular haloperidol and intramuscular lorazepam are standard treatments in the acute management of agitation and aggression. Although prolongation of the QT interval and sequelae, including torsade de pointes and death, have been reported for haloperidol (but not lorazepam), formal studies have been lacking. Volunteers with schizophrenia (n = 12) were administered a single intramuscular injection of 7.5 mg haloperidol or 4 mg lorazepam in a blinded, randomized, placebo-controlled crossover design. Serial EKGs and concurrent blood samples were obtained over 6 hours following each injection. Changes in the QT interval were evaluated, as were plasma drug and prolactin concentrations. Haloperidol injection increased the heart rate-corrected QT interval an average of 5.1 msec using Bazett's correction (QTb 90% confidence interval [CI]: 0.3, 9.8), 3.6 msec using Fridericia's correction (QTf 90% CI: 0.02, 7.2), and 4.2 msec using an empirically derived "baseline correction" (QT(ii) 90% CI: 0.3, 8.0). Effects of lorazepam on QT were nullified by correction for the heart rate elevation (QTb 3.8 msec, 90% CI: 0.6, 7.1; QTf 0.0 msec, 90% CI: -3.2, 3.4; QTii -2.3 msec, 90% CI: -6.6, 2.0). An association between QT prolongation and occurrence of extrapyramidal symptoms was observed. On average, intramuscular haloperidol led to minimal prolongation of the QT interval. This propensity is of theoretical concern in individuals with risk factors for torsade de pointes but seems unlikely to be a problem in the vast majority of patients.

Drug safety and efficacy evaluation of sertindole for schizophrenia

INTRODUCTION

Despite the progress in antipsychotic treatment, modern antipsychotic medication is still associated with side effects, reduced compliance, drug discontinuation and insufficient effects on negative and cognitive symptoms. Sertindole is an antipsychotic compound, with high affinity for dopamine D(2), serotonin 5-HT(2A), 5-HT(2C) and α(1)-adrenergic receptors, which has been reintroduced in the market after extended re-evaluation of its safety and risk-benefit profile.

AREAS COVERED

Sertindole's pharmacological profile, pharmacokinetics, neuophysiological properties, efficacy on positive, negative and cognitive symptoms and safety issues are covered in this article, based on a literature review from 1990 to 2012.

EXPERT OPINION

Based on five double-blind, randomized, placebo-, haloperidol- or risperidone-controlled studies in patients with schizophrenia, sertindole shows a comparable efficacy with haloperidol and risperidone on positive symptoms, while the effect on negative symptoms seems to be superior. Sertindole is generally well tolerated, but is associated with a dose-related QTc interval prolongation (+22 ms). Risk factors for drug-induced arrhythmia, such as cardiac diseases, congenital long QT syndrome, prolongated QTc at baseline, etc. and drug interactions should be considered before prescribing sertindole. To minimize cardiovascular risk, regular ECG recording is required. Sertindole can be an important second-line option for the treatment of schizophrenia for patients intolerant to at least one other antipsychotic. Further comparison with other SGAs and investigations on subgroups (e.g., children, elderly, first-episode, treatment-refractory patients, etc.) are still needed for a precise understanding of the therapeutic benefits and its role in schizophrenia therapy.

Cardiac slices as a predictive tool for arrhythmogenic potential of drugs and chemicals

IMPORTANCE OF THE FIELD

cardiac arrhythmia represents one of the primary safety pharmacological concerns in drug development. The most prominent example is drug induced ventricular tachycardia of the Torsade des Pointes type. The mechanism how this type of arrhythmia develops is a complex multi-cellular phenomenon. It can only be insufficiently reflected by cellular or molecular assays. However, organ models - such as Langendorff hearts - or in vivo experiments are expensive and time consuming and not suitable for assays requiring an increased throughput.

AREAS COVERED IN THIS REVIEW

here, we describe and review an assay bridging the gap between cardiomyocyte based assays and organ based systems - cardiac slices. This assay is reviewed in direct comparison with established safety pharmacological assays.

WHAT THE READER WILL GAIN

while slices have played an important role in brain research for > 2 decades, cardiac slices are experiencing a renaissance due to the novel challenges in safety pharmacology just in the last few years. Cardiac slices can be cultured and recorded over several days. It is possible to access electrophysiological data with a high number of electrodes - up to 256 electrodes - embedded in the surface of a microelectrode array.

TAKE HOME MESSAGE

cardiac slices close the gap between cellular and organ based assays in cardiac safety pharmacology. The tissue properties of a functional cardiac syncytium are more accurately reflected by a slice rather than a single cell.

Safety of sertindole versus risperidone in schizophrenia: principal results of the sertindole cohort prospective study (SCoP)

OBJECTIVE

To explore whether sertindole increases all-cause mortality or cardiac events requiring hospitalization, compared with risperidone.

METHOD

Multinational randomized, open-label, parallel-group study, with blinded classification of outcomes, in 9858 patients with schizophrenia.

RESULTS

After 14147 person-years, there was no effect of treatment on overall mortality (sertindole 64, risperidone 61 deaths, Hazard Ratio (HR) = 1.12 (90% CI: 0.83, 1.50)) or cardiac events requiring hospitalization [sertindole 10, risperidone 6, HR = 1.73 (95% CI: 0.63, 4.78)]: Of these, four were considered arrhythmia-related (three sertindole, one risperidone). Cardiac mortality was higher with sertindole (Independent Safety Committee (ISC): 31 vs. 12, HR=2.84 (95% CI: 1.45, 5.55), P = 0.0022; Investigators 17 vs. 8, HR=2.13 (95% CI: 0.91, 4.98), P = 0.081). There was no significant difference in completed suicide, but fewer sertindole recipients attempted suicide (ISC: 68 vs. 78, HR=0.93 (95% CI: 0.66, 1.29), P = 0.65; Investigators: 43 vs. 65, HR=0.67 (95% CI: 0.45, 0.99), P = 0.044).

CONCLUSION

Sertindole did not increase all-cause mortality, but cardiac mortality was higher and suicide attempts may be lower with sertindole.

Profile of olanzapine long-acting injection for the maintenance treatment of adult patients with schizophrenia

Olanzapine long-acting injection (OLAI) is a crystalline salt composed of olanzapine and pamoic acid, which permits a depot intramuscular formulation of olanzapine. The half-life of olanzapine pamoate is 30 days, and its steady state is reached approximately at 12 weeks. Oral supplementation of olanzapine is not required during OLAI initiation, according to Eli Lilly recommendations, although a study indicated that ≥60% of D(2) receptor occupancy was reached only by the fifth injection cycle. To date, a short-term, placebo-controlled study of 8 weeks in acutely ill patients and a long-term, controlled trial of 24 weeks in stabilized patients have been conducted. In both the studies, efficacy and safety were similar to those of oral olanzapine, with the exception of an acute adverse effect, the so-called inadvertent intravascular injection event, which occurred 1-3 hours after the injection with an incidence rate of 0.07% per injection. It consisted of symptoms that are similar to those reported in cases of oral olanzapine overdose. The most significant studies published to date, on the use of olanzapine pamoate in schizophrenia, are reviewed in this article. The pharmacodynamic and pharmacokinetic profile and related side effects of OLAI are reported.

Emerging role of sertindole in the management of schizophrenia

The atypical antipsychotic sertindole is a phenylindole-derived compound that has affinity for and functions as an antagonist at a number of receptor systems, including dopamine D2 receptors, 5-HT(2A) and 5-HT(2C) receptors, and α-1-noradrenergic receptors. Although previous data suggested that sertindole was well tolerated and had good efficacy against both positive and negative symptom clusters, reports of QT prolongation with sertindole prompted its voluntary removal from the market in 1998. After further safety analyses, it recently regained approval and was reintroduced to the European market for the treatment of schizophrenia, where its role in therapy among available atypicals remains unclear. This article evaluates the preclinical and clinical data regarding sertindole's effectiveness and concludes that sertindole continues to demonstrate a number of strengths, including effective management of both positive and negative symptoms, well-tolerated side effects (including little or no sedation, weight gain, and extrapyramidal side effects), and a superior procognitive profile that is unique among atypical antipsychotics. However, minor concerns regarding its sexual side effects and the major consideration of QT prolongation suggest that additional comparative effectiveness studies are needed to determine the superiority of sertindole vs other atypical antipsychotics recently introduced.

Apparent desensitization of the effects of sigma receptor ligand haloperidol in isolated rat and guinea pig hearts after chronic treatment

The supposed role of cardiac sigma receptors is fine tuning of contractility. Sigma receptors affect several ionic channels and hence their signaling is reflected by the electrophysiological properties of the heart. Numerous ligands of sigma receptors are known to prolong the QT interval and therefore cause a variety of arrhythmias, including severe ones. The effects of the prototypical sigma ligand haloperidol have been studied extensively in humans as well as in various animal models, primarily after acute administration. We examined the incidence of arrhythmias, changes in heart rate, and prolongation of QT interval in isolated Langendorff-perfused rat and guinea pig hearts after they were exposed to nanomolar concentrations of haloperidol. Hearts from both untreated (acute) and pretreated (chronic) animals were investigated. While QT prolongation and arrhythmias due to haloperidol administration were observed in untreated rat and guinea pig hearts, arrhythmias were completely prevented in both species of chronically treated animals. In treated guinea pigs, the results were generally less convincing. Since the hearts were exposed to nanomolar concentration of haloperidol, we conclude that our data may be explained by desensitization of sigma receptors.

Late potentials in the signal-averaged electrocardiogram in schizophrenia patients maintained on antipsychotic agents: a preliminary naturalistic study

In the present, preliminary, naturalistic study, cardiac ventricular late potentials (LPs), were measured in 33 physically healthy schizophrenia patients (13 - females and 26 - males, age - 45.5+/-8.8years) maintained on typical and atypical antipsychotic agents. These LPs represent delayed ventricular activation that might predispose to fatal ventricular arrhythmias and sudden cardiac death (SCD) in cardiac patients. Sixteen of the 33 patients ( approximately 48%) were found to be positive for LPs (compared to 3.7-6% in the general population). No association was found with any of the following: drug type, anti-cholinergic burden, daily dose of antipsychotic agents, age, gender, disease duration, QT(c) interval and QT dispersion. Further large-scale longitudinal prospective studies are warranted to substantiate our findings and to clarify their impact on the excess cardiac morbidity and mortality in schizophrenia patients.

Drug-induced block of cardiac HERG potassium channels and development of torsade de pointes arrhythmias: the case of antipsychotics

The prolongation of the cardiac repolarization process, a result of the blocking of the Human Ether-a-go-go Related Gene potassium channel, is an undesired accessory property shared by many pharmacological classes of non-cardiovascular drugs. Often the delayed cardiac repolarization process can be identified by a prolongation of the QT interval of the electrocardiograph. In these conditions, premature action potentials can trigger a dangerous polymorphic ventricular tachyarrhythmia, known as torsade de pointes, which occasionally can result in lethal ventricular fibrillation. In this work, brief descriptions of the electrophysiological basis of torsade de pointes and of the several pharmacological classes of torsadogenic drugs are given. Attention is focused on antipsychotics, with a deeper overview on the experimental and clinical reports about their torsadogenic properties.

Cardiac side effects of psychiatric drugs

This review describes the common effects of psychotropic drugs on the cardiovascular system and offers guidance for practical management. Selected reports from the literature describing common side effects associated with psychotropic drugs are reviewed, and suggestions for further reading are given throughout the text. Orthostatic hypotension is the most common adverse autonomic side effect of antipsychotic drugs. Among the atypical antipsychotics the risk of orthostatic hypotension is highest with clozapine and among the conventional drugs the risk is highest with low potency agents. Rarely, orthostatic hypotension may result in neurocardiogenic syncope. QTc prolongation can occur with all antipsychotics but an increased risk is seen with pimozide, thioridazine, sertindole and zotepine. QTc prolongation is a marker of arrhythmic risk. Torsade de pointe, a specific arrhythmia, may lead to syncope, dizziness or ventricular fibrillation and sudden death. Heart muscle disease presents most commonly in the elderly as chronic heart failure, but myocarditis and cardiomyopathy, although relatively rare, are devastating, but potentially reversible complications of psychotropic drug therapy have been particularly linked to clozapine treatment. Patients with severe mental illness (SMI) are a 'high risk' population with regard to cardiovascular morbidity and mortality. It is probable that many patients accumulate an excess of 'traditional' risk factors for the development of cardiovascular disease, but other mechanisms including psychotropic drugs may also be influential in increasing risk in this vulnerable group. These risks need to be seen in the context of the undoubted therapeutic efficacy of the psychotropic armamentarium and the relief that these drugs bring to those suffering from mental disorder.

Antipsychotic medication dispensing and risk of death in veterans and war widows 65 years and older

OBJECTIVE

To establish the instantaneous relative risk (RR) of death associated with individual antipsychotic drugs, carbamazepine and sodium valproate for those 65 years and older.

METHODS

Subjects dispensed antipsychotic drugs, sodium valproate or carbamazepine in 2003 or 2004 were analyzed as incident (N = 16,634) or prevalent (N = 9,831) users. Survival curves, mortality rates, and Cox proportional hazards models over two time periods were used to explore risk of death. The models were adjusted for age, sex, residential status, and psychotropic and medical drug dispensing. Olanzapine subjects were the reference group in the Cox regression. Subanalyses were performed for incident subjects with more than 30 days of follow-up and those dispensed cholinesterase inhibitors.

RESULTS

In the adjusted Cox proportional hazards models, haloperidol dispensing was consistently associated with an increased risk of death compared with olanzapine users (relative risk [RR] for incident users: 2.26, 95% confidence intervals (CI): 2.08-2.47; Wald statistic: 345.36, df = 1, p < or =0.001). There was some evidence of decreased survival with dispensing of higher haloperidol doses, although confounding by medical comorbidity cannot be excluded. Chlorpromazine (RR: 1.39, 95% CI: 1.15-1.67; Wald statistic: 12.08, df = 1, p <0.001) and risperidone (RR: 1.23, 95% CI: 1.07-1.40; Wald statistic: 9.12, df = 1, p = 0.003) dispensing were associated with increased risk of death in incident users.

CONCLUSION

These results should be interpreted cautiously because haloperidol and chlorpromazine are used in broader clinical contexts. However, in the absence of data from randomized trials, the safety profile of haloperidol should not be assumed to be benign. Antipsychotic drugs should not be studied as an aggregated group because their associated risks are not uniform.

Cardiovascular risks of atypical antipsychotic drug treatment

Atypical antipsychotics are the treatment of choice for patients with schizophrenia. They are generally better tolerated than conventional antipsychotics since most do not cause debilitating extrapyramidal symptoms. They are associated though with an array of cardiovascular adverse events that may affect morbid-mortality of schizophrenic patients. Orthostatic hypotension, electrocardiographic changes and metabolic syndrome (MS) are the main cardiovascular effects of atypical antipsychotics. They contribute to the overall disease burden associated with schizophrenia even though the benefit risk of such treatments still is highly favourable. We aim to review the main cardiovascular side effects of new atypical oral antipsychotics, the pharmacological mechanisms involved, and to which drugs they are particularly attributed.

Olanzapine prolongs cardiac repolarization by blocking the rapid component of the delayed rectifier potassium current

Prolongation of the QT interval has been observed during treatment with olanzapine, a thienobenzodiazepine antipsychotic agent. Our objectives were 1) to characterize the effects of olanzapine on cardiac repolarization and 2) to evaluate effects of olanzapine on the major time-dependent outward potassium current involved in cardiac repolarization, namely I(Kr) (I(Kr): rapid component of the delayed rectifier potassium current).Isolated, buffer-perfused guinea pig hearts (n = 40) were stimulated at different pacing cycle lengths (150-250 msec) and exposed to olanzapine at concentrations ranging from 1 to 100 microM. Olanzapine increased monophasic action potential duration measured at 90% repolarization (MAPD90) in a concentration-dependent manner by 6.7 +/- 0.7 msec at 3 microM but by 26.0 +/- 4.3 msec at 100 microM (250 msec cycle length). Increase in MAPD(90) was also reverse frequency dependent; 30 microM olanzapine increased MAPD90 by 28.0 +/- 6.2 msec at a pacing cycle length of 250 msec but by only 18.9 +/- 2.2 msec at a pacing cycle length of 150 msec. Experiments in HERG-transfected (HERG: human ether-a-gogo-related gene) HEK293 cells (n = 36) demonstrated concentration-dependent block of the rapid component (I(Kr)) of the delayed rectifier potassium current: tail current was decreased 50% at olanzapine 3.8 microM. Olanzapine possesses direct cardiac electrophysiological effects similar to those of class III anti-arrhythmic drugs. These effects were observed at concentrations that can be measured in patients under conditions of impaired drug elimination such as renal or hepatic insufficiency, during co-administration of other CYP1A2 substrates/inhibitors or after drug overdose. These results offer a new potential explanation for QT prolonging effects observed during olanzapine treatment in patients.

Risk of death associated with antipsychotic drug dispensing in residential aged care facilities

OBJECTIVE

To establish the instantaneous relative risk (RR) associated with the dispensing of individual antipsychotic drugs, carbamazepine and valproate for those > or = 65 years who resided in an aged care facility.

METHOD

The risk of death for incident users of antipsychotic drugs, carbamazepine and valproate in 2003 or 2004 who resided in an aged care facility was established using mortality rates and Cox proportional hazards models over two time periods. The regression models were adjusted for age, gender, medical and psychotropic drug dispensing, and a measure of overall medical comorbidity. Olanzapine users formed the referent group.

RESULTS

Haloperidol and chlorpromazine use were associated with the highest death rates. The instantaneous RR for those dispensed haloperidol was 1.67 (95% confidence intervals (CI) = 1.50-1.84, p < 0.001) and for chlorpromazine it was 1.75 (95%CI = 1.31-2.34, p < 0.001). The RR of death for haloperidol and chlorpromazine was higher in the regression model restricted to 60 days follow up (haloperidol RR = 2.17, 95%CI = 1.86-2.53, p < 0.001, chlorpromazine RR = 2.72, 95%CI = 1.84-4.01).

CONCLUSIONS

The increased risk associated with haloperidol and chlorpromazine dispensing should be interpreted cautiously because confounding by medical illness cannot be excluded despite adjusting the model for multiple variables. This study supports the findings from other data linkage studies that atypical antipsychotic medications are not associated with increased risk of death compared with conventional antipsychotic drugs.

Factors affecting outcome in schizophrenia and their relevance for psychopharmacological treatment

A major focus of current treatment research in schizophrenia is the determinants of long-term outcome, including functional outcome and general medical well being, rather than just specific domains of psychopathology such as positive and negative symptoms, mood symptoms, and cognitive impairment. This focus does not negate the importance of the latter issues but sees them as factors contributing to long-term outcome to variable extents. A long-term treatment focus facilitates a more clinically relevant assessment of benefits versus risks of available treatments. For instance, atypical antipsychotic drugs as a group have clear advantages for several important domains of efficacy that may influence long-term outcome, but are also more expensive over the long term. Use of some agents may also result in deleterious physical health consequences as well as large additional costs over the long term owing to metabolic adverse effects. The present paper focuses on several key issues in schizophrenia which are important determinants of long-term outcome in schizophrenia, or influence choice of antipsychotic drugs, or both, including: (i) duration of untreated psychosis; (ii) impact of relapse on long-term outcome; (iii) limited efficacy for specific domains of psychopathology of current treatments; (iv) mortality owing to suicide; and (v) mortality owing to other causes (e.g. cardiovascular disease).

A review of atypical antipsychotic drugs versus conventional medication in schizophrenia

Atypical antipsychotics are replacing conventional antipsychotics for the treatment of schizophrenia. They are considered to be at least as effective as conventional agents, with most producing fewer extrapyramidal symptoms. This review presents the evidence from published meta-analyses and describes differences in clinical effectiveness and tolerability between conventional and atypical antipsychotic agents. In addition, it discusses some of the more significant adverse effects including tardive dyskinesia, weight gain, diabetes and sudden death. Results from meta-analyses are conflicting, with some finding no significant advantages on measures of efficacy or tolerability for atypical antipsychotics over moderate daily doses of conventional drugs. Other results have shown that some atypical drugs have at least minor efficacy advantages over conventional comparators. Atypical antipsychotics exhibit a much reduced risk for tardive dyskinesia compared with conventional drugs. However, weight gain is more common with some atypical drugs (especially clozapine and olanzapine). Both conventional and atypical antipsychotics have been associated with diabetes, with most reports implicating both clozapine and olanzapine. Finally, atypical antipsychotics (unlike conventional drugs) have little or no effect on QT and are not associated with sudden death.

Clinical Pharmacokinetics of Atypical Antipsychotics

In the past, the information about the dose-clinical effectiveness of typical antipsychotics was not complete and this led to the risk of extrapyramidal adverse effects. This, together with the intention of improving patients' quality of life and therapeutic compliance, resulted in the development of atypical or second-generation antipsychotics (SGAs). This review will concentrate on the pharmacokinetics and metabolism of clozapine, risperidone, olanzapine, quetiapine, amisulpride, ziprasidone, aripiprazole and sertindole, and will discuss the main aspects of their pharmacodynamics. In psychopharmacology, therapeutic drug monitoring studies have generally concentrated on controlling compliance and avoiding adverse effects by keeping long-term exposure to the minimal effective blood concentration. The rationale for using therapeutic drug monitoring in relation to SGAs is still a matter of debate, but there is growing evidence that it can improve efficacy, especially when patients do not respond to therapeutic doses or when they develop adverse effects. Here, we review the literature concerning the relationships between plasma concentrations of SGAs and clinical responses by dividing the studies on the basis of the length of their observation periods. Studies with clozapine evidenced a positive relationship between plasma concentrations and clinical response, with a threshold of 350-420 ng/mL associated with good clinical response. The usefulness of therapeutic drug monitoring is well established because high plasma concentrations of clozapine can increase the risk of epileptic seizures. Plasma clozapine concentrations seem to be influenced by many factors such as altered cytochrome P450 1A4 activity, age, sex and smoking. The pharmacological effects of risperidone depend on the sum of the plasma concentrations of risperidone and its 9-hydroxyrisperidone metabolite, so monitoring the plasma concentrations of the parent compound alone can lead to erroneous interpretations. Despite a large variability in plasma drug concentrations, the lack of studies using fixed dosages, and discrepancies in the results, it seems that monitoring the plasma concentrations of the active moiety may be useful. However, no therapeutic plasma concentration range for risperidone has yet been clearly established. A plasma threshold concentration for parkinsonian side effects has been found to be 74 ng/mL. Moreover, therapeutic drug monitoring may be particularly useful in the switch between the oral and the long-acting injectable form. The reviewed studies on olanzapine strongly indicate a relationship between clinical outcomes and plasma concentrations. Olanzapine therapeutic drug monitoring can be considered very useful in assessing therapeutic efficacy and controlling adverse events. A therapeutic range of 20-50 ng/mL has been found. There is little evidence in favour of the existence of a relationship between plasma quetiapine concentrations and clinical responses, and an optimal therapeutic range has not been identified. Positron emission tomography studies of receptor blockade indicated a discrepancy between the time course of receptor occupancy and plasma quetiapine concentrations. The value of quetiapine plasma concentration monitoring in clinical practice is still controversial. Preliminary data suggested that a therapeutic plasma amisulpride concentration of 367 ng/mL was associated with clinical improvement. A therapeutic range of 100-400 ng/mL is proposed from non-systematic clinical experience. There is no direct evidence concerning optimal plasma concentration ranges of ziprasidone, aripiprazole or sertindole.

Analysis of proarrhythmic potential of antipsychotics risperidone and olanzapine in anesthetized dogs

In vitro electrophysiological studies have shown that second-generation antipsychotic drugs risperidone and olanzapine inhibit rapidly activating delayed rectifier K(+) currents and prolong action potential duration of the isolated ventricular myocardium. In this study, we analyzed in vivo cardiohemodynamic and electrophysiological profiles of risperidone and olanzapine using the halothane-anesthetized canine model to clarify their proarrhythmic potential. A clinically relevant dose of risperidone (0.03 mg/kg, i.v.) did not affect the ventricular repolarization process, whereas the supra-therapeutic doses (0.3 and 3 mg/kg, i.v.) prolonged the duration of monophasic action potential of the ventricle. Furthermore, the terminal repolarization period, an index of extent of electrical vulnerability, was prolonged after the supra-therapeutic doses. In contrast, therapeutic to supra-therapeutic doses of olanzapine (0.03-3 mg/kg, i.v.) hardly affected the ventricular repolarization process. Therefore, more caution has to be paid on the use of risperidone than olanzapine for patients with risks of the elevated plasma concentration.

Myocardium distribution of sertindole and its metabolite dehydrosertindole in guinea-pigs

Sertindole, like other atypical antipsychotics, has been shown to increase the action potential duration and QT interval in a concentration dependent manner, in in vitro electrophysiological studies. However, this does not always translate into increased duration of the QT interval, increased risk of torsade de pointes or sudden death in clinical practice. The reasons for these apparent discrepancies are unclear and many studies have underscored the importance of the interpretation of in vitro electrophysiological data in the context of other pharmacodynamic (e.g. cardiac ion channels target, receptor affinity) and pharmacokinetic parameters (total plasma drug concentration and drug distribution). To address the possible relevance of the concentrations used in experimental studies, the myocardium distribution of sertindole and its metabolite was determined after single and repeated intraperitoneal administration to guinea-pigs. The data suggest that the plasma concentration appears to predict the concentration in the myocardium and that the myocardium concentrations of sertindole are 3.1 times higher than plasma concentrations. Using these data, the relevance of in vitro electrophysiological studies to clinical plasma concentrations has been appraised.

Antipsychotikainduzierte QT-Verlängerung

Prolongation of myocardial repolarisation, i.e. lengthening of the QT interval on surface electrocardiogram, has been recognised as a side effect of many drugs, including antipsychotics. In predisposed individuals, abnormal excessive QT prolongation and severe ventricular arrhythmias (the ventricular tachycardia type 'torsade de pointes', or TdP) may occur. In almost all cases, additional factors are present that increase the propensity of patients to develop TdP, such as serum hypokalemia, the combination of drugs prolonging repolarisation, overdosing, intoxication, and factors interfering with drug metabolism and excretion. Serum hypokalemia and/or bradycardia may induce TdP alone, in the absence of drugs prolonging the QT interval. Experimental studies demonstrate that prolongation of myocardial repolarisation is a class effect of neuroleptics. Clinically, the extent to which individual drugs prolong the QT interval varies. Among the antipsychotics, thioridazine has the greatest propensity to induce abnormal QT prolongations and TdP. Case reports of TdP with other antipsychotics have been published. Physicians prescribing physicians these drugs must be aware that they can induce proarrhythmia in individual cases. They should also be aware of the circumstances which are necessary for abnormal QT prolongation and TdP to develop. Patients should be monitored with regard to these risk factors before and during drug treatment.

Mortality in schizophrenia

PURPOSE

The purpose of this article is to describe the current status of knowledge on excess mortality in schizophrenia and its causative factors, and to expand upon previous work evaluating approaches that may reduce mortality rates.

METHODS

Literature available since 1995 was identified in a computerized search of the bibliographical databases Medline and Embase, using the topics 'mortality' and 'schizophrenia', and in a cross-reference search for articles that were particularly relevant.

RESULTS

Schizophrenia is associated with mortality rates that are two to three times higher than those expected or observed in the general population. This excess of mortality is accounted for by a combination of an increased risk of suicide, in particular in young male patients soon after diagnosis, and more importantly, a higher number of natural deaths. In order to diminish the level of suicide among people with schizophrenia, the majority of research has focused on the identification of risk factors that predispose patients to attempt or commit suicide, while unhealthy styles, polypharmacy and inadequate healthcare have been shown to contribute to the high natural mortality. The link between the use of antipychotics and mortality has not been yet clarified.

CONCLUSION

Dramatically increased mortality of schizophrenia patients is well established. It is time to move beyond this topic, and work towards interventions that aim at reducing the mortality risk in such patients.

Treatment with the new antipsychotic sertindole for late-occurring undesirable movement effects

Conventional antipsychotics are often associated with late-occurring undesirable movement effects. To gain more experience with newer antipsychotic agents, 151 patients in an acute admissions department were switched from treatment with conventional antipsychotics to sertindole between late 1996 and early 1998. Four of these patients had tardive dyskinesia, tardive dystonia and/or tardive akathisia. The effect of changing to sertindole was measured using specific rating scales for undesirable movement effects. Three of the four patients apparently recovered from the movement disorders after switching to sertindole. In one patient, sertindole monotherapy was not sufficient to reduce the movement effects, but combination treatment with tetrabenazine resulted in a greater reduction in extrapyrimidal symptoms. Because these are case reports, no direct conclusions can be drawn. However, the beneficial effect of sertindole on severe, late-occurring movement disorders, as observed in four difficult-to-treat patients, appears to be promising.

Risperidone-induced action potential prolongation is attenuated by increased repolarization reserve due to concomitant block of ICa,L

The neuroleptic risperidone is an effective blocker of the rapidly activating component of the delayed rectifier current (I(Kr)) and hence is expected to prolong cardiac action potential duration (APD). However, unlike with other typical I(Kr) blockers we failed to demonstrate a marked prolongation of late repolarization with risperidone. It is hypothesized that the APD-prolonging effect of risperidone is masked by the high repolarization reserve due to the prominent delayed rectifier currents I(Kr) and I(Ks) in guinea pig papillary muscle. Action potentials and force of contraction were recorded in isolated guinea pig papillary muscles. L-type calcium current I(Ca,L) and I(Kr) were measured using the standard patch clamp technique in single ventricular cardiomyocytes. Reduction of the repolarization reserve by the blocking of I(Ks) with chromanol 239B augmented the effect of the selective I(Kr) blocker E-4031, but not of risperidone, although both drugs completely blocked I(Kr). In contrast to E-4031 risperidone markedly reduced the force of contraction due to the partial blocking of I(Ca,L) in the same concentration range as required for block of I(Kr). Reduction of the repolarization reserve by the blocking of I(Ks) cannot exacerbate the APD-prolonging effect of risperidone. However, even incomplete concomitant blocking of I(Ca,L) attenuates the APD-prolonging effect of the complete blocking of I(Kr). This behaviour may explain the small APD-prolonging effect of risperidone despite the drug's robust blocking of I(Kr).

Atypical antipsychotics: from potassium channels to torsade de pointes and sudden death

Syncope and sudden death are features of schizophrenia that can be attributed to ischaemic heart disease, the use of antipsychotics (because of proarrhythmia or other reasons such as pharyngeal dyskinesia) or the psychiatric disease itself. Cases have been described with most antipsychotics and have led to the withdrawal, temporary suspension from the market or restricted use of antipsychotics, such as sultopride, droperidol, sertindole or thioridazine. Reviewing the available data shows that all antipsychotics tested affect the cardiac potassium channel, with the concentration that produces 50% inhibition (IC50) ranging from 1 nmol/L (haloperidol) to 6 micromol/L (olanzapine). Experimental in vitro or in vivo electrophysiological studies have shown a dose-dependent increase in the duration of the action potential with various degrees of indicators of serious arrhythmogenicity. However, this does not always translate clinically into an increased duration of the QT interval or increased risk of torsade de pointes or sudden death in clinical trials or pharmacoepidemiological studies. In turn, QT prolongation in clinical trials does not always translate to an increased risk of torsade de pointes or sudden death. The reasons for these apparent discrepancies are unclear and could be related to insufficiently powered field studies, low plasma and tissue drug concentrations with reference to in vitro data or drug effects on other receptors or ion channels that have a protective effect. Alternatively, risks that were not apparent from preclinical or clinical data could be related to the use of the drug in high-risk patients, metabolic interactions or other factors that would only be encountered in large postmarketing populations. The assessment of cardiovascular safety, both preclinical and during premarketing clinical trials, needs to be supported by appropriately powered pharmacoepidemiology studies.

Adverse cardiac effects associated with clozapine

OBJECTIVE

To review the published literature on serious adverse cardiac events associated with the atypical antipsychotic agent, clozapine, and to make recommendations for cardiac assessment of candidates for clozapine treatment and for monitoring of cardiac status after treatment is initiated.

DATA SOURCES

We searched the PubMed and MEDLINE databases for articles published from 1970 to 2004 that contain the keywords "clozapine and myocarditis," "clozapine and cardiomyopathy," "clozapine and cardiotoxicity," "clozapine and sudden death" or "clozapine and mortality." We also manually searched the bibliographies of these articles for related sources.

STUDY SELECTION

We reviewed the 30 case reports, case series, laboratory and clinical trials, data mining studies, and previous reviews identified by this search.

DATA SYNTHESIS

Recent evidence suggests that clozapine is associated with a low (0.015% to 0.188%) risk of potentially fatal myocarditis or cardiomyopathy. The drug is not known to be independently associated with pathologic prolongation of the QTc interval, but it may contribute to pathologic QTc prolongation in patients with other risk factors for this condition.

CONCLUSIONS

The low risk of a serious adverse cardiac event should be outweighed by a reduction in suicide risk for most patients taking clozapine. We provide recommendations for assessing and monitoring cardiac status in patients prior to and after initiation of treatment with clozapine.