Cardiovascular adverse effects of antipsychotic drugs

LACK OF HINOKITIOL (BETA-THUJAPLICIN) CARCINOGENICITY IN F344/DuCrj RATS

Chronic toxicity and carcinogenicity of hinokitiol (beta-thujaplicin), used as an antibiotic and fungicidal agent of a food additive, was examined in both sexes of F344/DuCrj (F344) rats. In this chronic toxicity study, groups of 10 rats of each sex were given a diet containing hinokitiol at doses of 0, 0.005, 0.015 and 0.05% for 52 weeks. No treatment-related adverse effects were noted in the survival rate, general condition, body weights, food consumption, urinalysis, hematology and clinical chemistry. Slight but significant elevation of spleen and liver weights was noted in both sexes given 0.05% hinokitiol, along with an increase in hemosiderin deposits in male spleens, related to chelator binding of iron, together with slight centrilobular hypertrophy of male hepatocytes. However, these alterations were negligible and not toxicologically significant. In the carcinogenicity study, groups of 50 female and 50 male rats were given a diet containing hinokitiol at doses of 0, 0.005, 0.015 and 0.05% (excluding 0.005% in females). No treatment-related changes in survival rate, general condition, body weight, food consumption, hematology and organ weights were noted. Detailed histopathological examination revealed no treatment-related increase in the incidences of any neoplastic lesions. The results demonstrate that hinokitiol is not carcinogenic in F344 rats of either sex.

Psychotropic Drugs and the Perioperative Period: A Proposal for a Guideline in Elective Surgery

Evidence-based guidelines for the perioperative management of psychotropic drugs are lacking. The level of evidence is low and is based on case reports, open trials, and non-systematic reviews. However, the interactions and effects mentioned indicate that patients who use psychotropics and require surgery have an enhanced perioperative risk. A group of clinicians from several clinical disciplines determined which risks should be considered in an integrated preoperative assessment, as well as how psychotropics might interfere with these risks. The risks that should be considered in the perioperative period are the extent of the surgery, the patient's physical state, anesthesia, the direct and indirect (Phase I and II) effects of psychotropics, risk of withdrawal symptoms, and risk of psychiatric recurrence or relapse. Because of new drug developments, the risk of interactions increases. The literature has not provided articles that systematically address these risks. On the basis of a systematic analysis of the available literature guided by the formulated perioperative risks, a proposal for the perioperative management of psychotropics was formulated. Patients who use lithium, monoamine oxidase inhibitors, tricyclics, and clozepine have serious drug-drug interactions, with increased physical risks, including withdrawal, and therefore qualify for American Society of Anesthesiologists (ASA) Classification 3. From the perspective of the physical risk, they require discontinuation. However, from the perspective of the risk of withdrawal and psychiatric relapse and recurrence, these patients deserve intensive, integrated anesthetic/psychiatric management. For patients on selective serotonin reuptake inhibitors (SSRIs) who are mentally and physical stable (ASA Classification 2), the risk of withdrawal seems to justify their continuation. Yet, patients on SSRIs with higher physical or psychiatric risks should be seen in consultation. Both the physical and psychiatric risks of patients who use antipsychotics and other antidepressants should be regarded as enhanced. From a physical perspective, they qualify for ASA Classification 2. From the perspective of withdrawal and psychiatric recurrence or relapse, they should be seen by (their) psychiatrists. Preoperative assessment clinics offer the opportunity to assess and evaluate these risks in order to deliver patient-tailored integrated care. Authors propose a model for quality management.

Perioperative Management for Chronic Schizophrenic Patients

Schizophrenic patients are at increased risk for perioperative complications, as their biological response to stress is impaired. The increased complications are associated with physical disorders, antipsychotic or hazardous health behaviors, and interactions between antipsychotics and anesthetic drugs. Thus, anesthesiologists must not only be aware of the perioperative problems of these patients but must also learn how to manage their perioperative course.

Effects of drugs with muscle-related side effects and affinity for calsequestrin on the calcium regulatory function of sarcoplasmic reticulum microsomes

The tight regulation of Ca2+ release to and clearance from the cytosol is essential for normal excitation-contraction coupling in both skeletal and cardiac muscles. Calsequestrin (CSQ) is one of the major components in the sarcoplasmic reticulum (SR) of both skeletal and cardiac muscle. Previously, we showed that several pharmaceutical drugs, such as phenothiazine derivatives, tricyclic antidepressants, anthracycline derivatives, and other hydrophobic compounds bind CSQ with K(d) values in the micromolar range and significantly reduce the Ca2+ binding capacity of cardiac CSQ (Mol Pharmacol 67:97-104, 2005). Because of its key role in Ca2+ regulation, this interference with CSQ function could well produce adverse physiological consequences and potentially be linked to the known muscle-related side effects of these drugs. To further understand the molecular mechanism of undesirable drug effects or adverse drug reactions among those compounds, we examined their effect on the SR microsome. The results clearly showed that these compounds affect Ca2+ release and reduce the total Ca2+ content of the purified SR microsomes, matching well with our previous results with purified recombinant CSQ. Liquid chromatography-mass spectrometry/mass spectrometry showed that the antipsychotic drug trifluoperazine penetrates well into the SR microsome as expected from the reported and calculated log S (aqueous solubility) and log P (partition coefficient) values among the phenothiazine derivatives. We therefore propose that a certain portion of the muscle-related (both cardiac and skeletal) complications of these drugs is caused by the altered Ca2+ regulation of the SR mediated by their adverse interaction with CSQ.

Assessing cardiovascular risks of olanzapine treatment: a 6-month study versus haloperidol in schizophrenia patients

The introduction of second generation antipsychotics (SGA) represents a major advance in the treatment of schizophrenia. Concerns about the metabolic and cardiovascular adverse effects of the SGA have been widely disseminated. The benefits and risks of these drugs have been studied with a focus on particular organ systems. A basic principle of prevention is that the intensity of risk-reduction therapy should be adjusted to a individual's absolute risk. Hence, the first step is to assess an individual's risk status. The present study was designed to evaluate whether there is an added cardiovascular disease (CVD) risk in switching schizophrenia patients from typical antipsychotics to the SGA olanzapine. Risk status was determined by a 10-year risk assessment as recommended by the USA National Heart, Lung, and Blood Institute. This was carried out with Framingham scoring to identify individuals whose short-term (10-year) risk warrants consideration of intensive treatment. This risk was calculated for schizophrenia patients who were treated by haloperidol for a minimum period of 6 months and again following 6 months of exposure to olanzapine. Forty-three patients fulfilled inclusion criteria. There were 25 male and 18 female patients (mean age 40.7+/-2.4 years). The mean 10-year percentage risk of CVD for the group while on haloperidol treatment was 4.58+/-0.9 and, after 6 months of exposure to olanzapine, this was reduced to 4.12+/-0.9. Changes in the total risk and each evaluated risk variable were not statistically significant, except for a decrease in resting systolic blood pressure. Switching schizophrenia patients from typical antipsychotic treatment to olanzapine is safe and does not increase the long-term risk of cardiovascular disease.

N-terminal fragment of B-type natriuretic peptide (NT-proBNP), a marker of cardiac safety during antipsychotic treatment

BACKGROUND: The potential cardiotoxicity of antipsychotic drugs is well known. The N-terminal fragment of B-type natriuretic peptide (NT-proBNP) is considered to be a possible biomarker in clinical practice for the diagnosis and prognosis in patients with suspected heart failure. This pilot evaluation tests the influence of antipsychotic drugs on NT-proBNP concentration in view of the hypothesis that NT-proBNP could be used as marker for the tolerability and safety of antipsychotic medications. METHODS: On a routine basis, patient's blood samples were examined for NT-proBNP on days 0, 7 and 21 after initiation of a new antipsychotic monotherapy. All plasma samples were analysed for NT-proBNP using an electrochemiluminiscence immunoassay "ECLIA" (proBNP kit, Roche Diagnostics, Mannheim, Germany) on an Elecsys 2010 analyser. RESULTS: A difference was found in NT-proBNP values at day 0 between patients younger versus older than 40 years. Also women had comparatively lower NTproBNP on days 7 and 21. Smokers' levels of NT-proBNP values decreased more from day 0 to day 7. CONCLUSION: Our results suggest that antipsychotic medication influences the plasma concentration of NT-proBNP, suggesting a possible method to identify high-risk-patients for cardiovascular adverse effects due to antipsychotic medication. Larger studies should further test this hypothesis.

Inhibition of human ether-a-go-go-related gene K+ channel and IKr of guinea pig cardiomyocytes by antipsychotic drug trifluoperazine

Trifluoperazine, a commonly used antipsychotic drug, has been known to induce QT prolongation and torsades de pointes, which can cause sudden death. We studied the effects of trifluoperazine on the human ether-a-go-go-related gene (HERG) channel expressed in Xenopus oocytes and on the delayed rectifier K(+) current of guinea pig cardiomyocytes. The application of trifluoperazine showed a dose-dependent decrease in current amplitudes at the end of voltage steps and tail currents of HERG. The IC(50) for a trifluoperazine block of HERG current progressively decreased according to depolarization: IC(50) values at -40, 0, and +40 mV were 21.6, 16.6, and 9.29 microM, respectively. The voltage dependence of the block could be fitted with a monoexponential function, and the fractional electrical distance was estimated to be delta = 0.65. The block of HERG by trifluoperazine was use-dependent, exhibiting more rapid onset and greater steady-state block at higher frequencies of activation; there was partial relief of the block with decreasing frequency. In guinea pig ventricular myocytes, bath applications of 0.5 and 2 microM trifluoperazine at 36 degrees C blocked the rapidly activating delayed rectifier K(+) current by 32.4 and 72.9%, respectively; however, the same concentrations of trifluoperazine failed to significantly block the slowly activating delayed rectifier K(+) current. Our findings suggest the arrhythmogenic side effect of trifluoperazine is caused by a blockade of HERG and the rapid component of the delayed rectifier K(+) current rather than by the blockade of the slow component.

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.

Severe tachycardia following low-dose clozapine treatment

OBJECTIVE

To report a case of severe and sustained tachycardia that developed asymptomatically on a low dose of clozapine (150 mg daily).

METHOD

Case report.

RESULTS

Serially monitored 24 h heart rate after the introduction of clozapine showed an increase in the 24 h mean from 87 to 126 bpm, a reduction of pulse variability and anomalies in sleep-wake regulation. Cessation of clozapine was followed by a rapid return to preclozapine activity. Application of the Naranjo Adverse Drug Reaction Probability Scale indicated a probable relationship between clozapine and the sustained tachycardia.

CONCLUSIONS

Severe and sustained tachycardia can develop asymptomatically with a relatively low dose of clozapine and a slow titration rate. The severity of the tachycardia may not be revealed in isolated pulse measurements and may escape clinical detection without closer monitoring of heart rate.

QT PRODACT: Evaluation of the Potential of Compounds to Cause QT Interval Prolongation by Action Potential Assays Using Guinea-Pig Papillary Muscles

Certain compounds that prolong QT interval in humans have little or no effect on action-potential (AP) duration used traditionally, but they inhibit rapidly-activated-delayed-rectifier potassium currents (IKr) and/or human ether-a-go-go-related gene (hERG) currents. In this study using isolated guinea-pig papillary muscles, we investigated whether new parameters in AP assays can detect the inhibitory effects of various compounds on IKr and/or hERG currents with high sensitivity. The difference in AP duration between 60% and 30% repolarization, 90% and 60% repolarization, and 90% and 30% repolarization (APD30-60, APD60-90, and APD30-90, respectively) were calculated as the new parameters. All the 15 IKr and/or hERG current inhibitors that have been reported (9 compounds) or not reported (6 compounds) to inhibit calcium currents prolonged APD30-60, APD60-90, and/or APD30-90; and 8 of the 15 inhibitors prolonged APD30-60, APD60-90, and/or APD30-90 more potently than APD90. The APD30-60, APD60-90, and APD30-90 measurements revealed no difference in sensitivity when evaluating the effects of the IKr and/or hERG current inhibitors on the three parameters. On the other hand, compounds with little or no effect on hERG currents had no effect on APD30-60, APD60-90, or APD30-90. Therefore, it is concluded that in AP assays using isolated guinea-pig papillary muscles, APD30-60, APD60-90, and APD30-90 are useful indexes for evaluating the inhibitory effects of compounds including mixed ion-channel blockers on IKr and/or hERG currents.

Reversible cardiomyopathy as the autonomic involvement of neuroleptic malignant syndrome

Autonomic disturbance develops commonly in neuroleptic malignant syndrome (NMS). However, the association of cardiomyopathy is rare. Takotsubo-shaped cardiomyopathy is a unique reversible heart syndrome involving autonomic disturbance and mimicking myocardial infarction. We report a 63-year-old woman who developed Takotsubo-shaped cardiomyopathy during the course of NMS. Our case suggests the occurrence of reversible cardiomyopathy as the autonomic involvement of NMS.

Inhibition of hERG K+ currents by antimalarial drugs in stably transfected HEK293 cells

Several antimalarial drugs are known to produce a QT interval prolongation via a blockade of the rapidly activating delayed rectifier K+ current (IKr), encoded by the human-ether-a-go-go-related gene (hERG). We investigated the influence of lumefantrine and its major metabolite desbutyl-lumefantrine, as well as halofantrine, chloroquine, and mefloquine, on wild type hERG K+ channels in stably transfected human embryonic kidney cells (HEK293) using the whole cell patch-clamp technique. All of the tested antimalarial drugs inhibited the hERG K+ channels in a concentration- and time-dependent manner. Only halofantrine blocked hERG tail currents voltage-dependently. The ranking of the half-maximal inhibitory concentrations (IC50) of the antimalarials was: halofantrine (0.04 microM)<chloroquine (2.5 microM)<mefloquine (2.6 microM)<desbutyl-lumefantrine (5.5 microM)<lumefantrine (8.1 microM). Lumefantrine and desbutyl-lumefantrine showed a slower inhibition of IKr than the other tested antimalarials. In conclusion, lumefantrine and desbutyl-lumefantrine inhibited significantly the hERG tail current with a higher IC50-value than mefloquine, chloroquine and halofantrine. This, together with the calculated cardiac safety indices, suggests that lumefantrine and desbutyl-lumefantrine have a weaker proarrhythmic potential than their comparator compounds.

The utility of hERG and repolarization assays in evaluating delayed cardiac repolarization: influence of multi-channel block

Drug-induced delayed cardiac repolarization is a recognized risk factor for proarrhythmia and is associated with block of IKr (the potassium current encoded by the human ether-a- go-go-related gene [hERG]). To evaluate the utility of 2 in vitro assays widely used to assess delayed repolarization, we compared the effects of haloperidol and 9 structurally diverse drugs in a hERG and repolarization (canine Purkinje fiber action potential duration [APD]) assay over wide concentrations. Despite potent hERG current block (IC50 = 0.174 microM), haloperidol elicited a bell-shaped concentration-response relationship for APD prolongation, with lesser prolongation (and reduced plateau height) observed with concentrations eliciting maximal hERG block, consistent with multi-channel block at higher concentrations. Consistent with this hypothesis, APD prolongation with the specific IKr blocker dofetilide was a) reduced by concomitant administration of nifedipine (calcium current block) and b) reversed by lidocaine (late sodium current block). Additional studies demonstrated prominent (>50%) hERG inhibition with most (9/10) drugs despite wide APD changes (158% prolongation - 16% shortening), consistent with multi-channel block. The poor correlation between hERG and repolarization assays suggests that the hERG assay oversimplifies drug effects on the complex repolarization process for drugs demonstrating multi-channel block and that neither assay alone adequately predicts proarrhythmic risk.

Heart rate dynamics and their relationship to psychotic symptom severity in clozapine-treated schizophrenic subjects

The analysis of heart rate variability (HRV) has proven to be useful in evaluating the neuroautonomic dysfunctions associated with various clinical conditions. The purpose of this study was to investigate the linear and non-linear dynamic measures of HRV, and to evaluate their relationship with the psychotic symptom severity, in clozapine-treated schizophrenic subjects. Fifty schizophrenic patients treated with clozapine as monotherapy and 50 normal control subjects were evaluated for HRV analysis. The HRV measurements were obtained from a 30-min resting electrocardiogram (ECG). The severity of psychotic symptoms was assessed using the Positive and Negative Syndrome Scale (PANSS). In the patient group, the complexity and symbolic dynamics measures as well as the time and frequency domain measures of HRV were significantly lower than in the control group (P<0.01). The intermediate-term fractal scaling component value was significantly higher in the patient group (P<0.01). The PANSS total score and the positive symptom subscale score had significant negative correlations with the sample entropy (SampEn) value (P<0.01). In conclusion, schizophrenic patients treated with clozapine had markedly different heart rate dynamics compared to normal control subjects. The severity of psychotic symptoms was associated with the SampEn value, suggesting that the non-linear complexity measure might be useful in assessing the neuroautonomic dysfunction in schizophrenia.

Pharmacokinetic Factors in the Adverse Cardiovascular Effects of Antipsychotic Drugs

Antipsychotics may cause serious adverse cardiovascular effects, including prolonged QT interval and sudden death. This review considers antipsychotic-induced cardiovascular events from three perspectives: high-risk drugs, high-risk individuals and high-risk drug interactions. Pharmacokinetic drug interactions involving the cytochrome P450 (CYP) enzymatic pathway and pharmacodynamic interactions leading to direct cardiotoxic effects are discussed. Original reports on antipsychotic-induced drug interactions are reviewed, with consideration of management guidelines. The literature was reviewed from 1 January 1966 to 1 February 2002. The literature search revealed only 12 original articles published on antipsychotic drug interactions leading to cardiovascular adverse events. Only 4 of the 12 reports were prospective studies; the remainder were either retrospective or anecdotal.Although poor study designs preclude a definitive statement, it appears that pharmacokinetic interactions primarily involved the CYP2D6 and CYP3A4 enzymatic pathways. Those involving the CYP2D6 isozyme included interactions with tricyclic antidepressants, selective serotonergic reuptake inhibitors and beta-blockers. Among these drug interactions, tricyclic antidepressants were most likely to reach clinical significance because of their limited therapeutic index. Drug interactions related to the CYP3A4 pathway were generally less severe, and involved high-potency antipsychotics coadministered with inhibitors such as clarithromycin. Strategies are discussed for the management of adverse cardiovascular events related to antipsychotic drug interactions, including the use of an algorithm. Large, randomised, placebo-controlled studies with strict inclusion criteria are needed to determine the role that antipsychotics play in QT prolongation and sudden death.

Insuffisances cardiaques d’origine médicamenteuse (en dehors des anthracyclines)

The principal drugs implicated in or disclosing cardiac insufficiency are drawn from a review of the literature and observations by the French national pharmacovigilance database, from 1984 to April 2003. Several pharmacological classes are identified: in addition to antimitotic drugs, such as anthracyclines, many drugs are implicated in cardiac insufficiency, e.g. immunomodulators, anti-inflammatory drugs (including coxibs), antiarrhythmic drugs, anaesthetic drugs, antipsychotic drugs, and antidiabetic drugs (including glitazones). It is usual to classify these drugs according to three categories: (i) drugs likely to cause cardiac insufficiency de novo (such as cyclophosphamide, paclitaxel, mitoxantrone, interferons, interleukin-2 etc.); (ii) drugs likely to worsen preexisting cardiac insufficiency (such as antiarrhythmics, beta-blockers, calcium antagonists, nonsteroidal and steroidal anti-inflammatory drugs, sympathomimetic drugs etc.); and (iii) drugs only occasionally causing cardiac insufficiency. This review shows that this classification is, in fact, artificial. If cardiac toxicity is a constant concern when using antimitotic drugs or some immunomodulator drugs, it is advisable to exercise caution in the use of many other drugs when treating patients with cardiac insufficiency, even if the clinical situation is well controlled. In particular, drug-drug interactions and patient medical history must be taken into account.

Quetiapine poisoning

STUDY OBJECTIVE

We describe the effects of quetiapine in overdose.

METHODS

Quetiapine poisonings were identified from a prospective database of poisoning admissions to a regional toxicology service. Data extracted included details of ingestion, clinical features, investigations (including ECG), and other outcomes (length of stay and ICU admission rate).

RESULTS

There were 45 cases of quetiapine overdose, of which 18 patients with quetiapine assay results were included. Median length of stay was 35 hours (interquartile range [IQR] 14 to 42 hours) for the 18 patients, and 9 were admitted to the ICU. The median ingested dose was 3.5 g (IQR 1.7 to 6.2 g), and reported ingested dose was highly correlated with estimated peak drug concentration (r(2)=0.84; P<.0001), confirming patient-provided history of ingestion. Seizures occurred in 2 patients, delirium occurred in 3 patients, and mechanical ventilation was required in 4 patients. No arrhythmias or deaths occurred. Six of the 18 patients ingested quetiapine alone, with a median length of stay of 35 hours, and 3 were admitted to the ICU. In 1 patient who ingested 24 g, hypotension and seizures occurred. For 10 patients for whom ECGs were available and who had ingested no cardiotoxic drugs, tachycardia occurred in 8 patients. For these 10 patients, the mean corrected QT (QTc) interval was increased at 487 ms, but the mean uncorrected QT interval was 349 ms. Reported dose and peak quetiapine concentrations were significantly associated with ICU admission and length of stay more than 24 hours. A reported dose less than 3 g and a Glasgow Coma Scale score not less than 15 predicted patients not requiring ICU admission or length of stay more than 24 hours.

CONCLUSION

Quetiapine overdose causes central nervous system depression and sinus tachycardia. In large overdoses, patients may require intubation and ventilation for associated respiratory depression. Although a prolonged QTc occurs, its clinical significance is unclear because it is most likely caused by an overcorrection caused by the tachycardia. In our experience, a reported dose of less than 3 g for patients who are not drowsy (with a Glasgow Coma Scale score of 15) at least 4 hours after ingestion and who did not coingest another toxic agent defined a group not requiring ICU admission or inpatient admission greater than 24 hours.

Prolonged QTc intervals in medicated patients with schizophrenia

Psychotropic drugs have been associated with sudden deaths and the lengthening of corrected-QT interval (QTc) on the electrocardiogram which may be a precursor of life-threatening arrhythmias as reported with some of these drugs. The objectives of this study were to measure the frequency of QTc lengthening in patients with schizophrenia receiving psychotropic drugs, and to assess whether QTc lengthening was associated with certain psychotropic drugs and other risk factors. One hundred and sixty three patients with schizophrenia (104 males and 59 females) were included in the study. Clinical and demographic data were collected from the case records. One hundred healthy volunteers were recruited to establish values for upper limits of normal for measurement of QTc interval and dispersion. Eleven (6.7%) of the patients had a prolonged QTc interval. The significant predictors obtained from a logistic regression modelling were chlorpromazine, flupenthixol decanoate and fluphenazine decanoate. Caution should be exercised and monitoring with ECG should be considered in patients prescribed chlorpromazine and depot antipsychotic medications even at recommended doses.

An audit of post-operative nausea and vomiting, following cardiac surgery: scope of the problem

Post-operative nausea and vomiting is a major problem for patients following cardiac surgery. The literature in this area identifies that there are a number of individual patient and post-operative factors which increase the risk of post-operative nausea and vomiting, including female gender, non-smoker, age, use of opioids, pain and anxiety. An audit involving 200 patients, who had undergone cardiac surgery was implemented to assess/evaluate the incidence of nausea and vomiting for this patient group. Data collected included information relating to nausea and vomiting, pain, consumption of morphine and other individual patient variables. The results suggest that nausea and vomiting, is experienced by a large number of patients after cardiac surgery (67%), with the majority suffering on the first day after surgery. The duration of nausea and vomiting for most is short, but for a significant number (7%) it can last up to one-quarter of their initial post-operative course. The paper discusses key implications for practice arising from this project.

Structural and functional basis for the long QT syndrome: relevance to veterinary patients

Long QT syndrome (LQTS) is a condition characterized by prolongation of ventricular repolarization and is manifested clinically by lengthening of the QT interval on the surface ECG. Whereas inherited forms of LQTS associated with mutations in the genes that encode ion channel proteins are identified only in humans, the acquired form of LQTS occurs in humans and companion animal species. Often, acquired LQTS is associated with drug-induced block of the cardiac K+ current designated I(Kr). However, not all drugs that induce potentially fatal ventricular arrhythmias antagonize I(Kr), and not all drugs that block I(Kr), are associated with ventricular arrhythmias. In clinical practice, the extent of QT interval prolongation and risk of ventricular arrhythmia associated with antagonism of I(Kr) are modulated by pharmacokinetic and pharmacodynamic variables. Veterinarians can influence some of the potential risk factors (eg, drug dosage, route of drug administration, presence or absence of concurrent drug therapy, and patient electrolyte status) but not all (eg, patient gender/genetic background). Veterinarians need to be aware of the potential for acquired LQTS during therapy with drugs identified as blockers of HERG channels and I(Kr).

Droperidol in the emergency department: is it safe?

Droperidol is an antipsychotic and antiemetic drug that has been used extensively by emergency physicians, psychiatrists, and anesthesiologists worldwide since 1967. It also has been used effectively for other diverse conditions, such as treatment of headache and vertigo. As of January 2001, Droperidol was no longer available in Europe after its founder, Janssen-Cilag Pharmaceuticals, discontinued its distribution. In December 2001, the United States Food and Drug Administration (FDA) placed a black box warning on the use of Droperidol in response to an association between Droperidol and fatal cardiac dysrhythmias, such as torsade de pointes, resulting from prolongation of the QT interval. In this review we closely examine the pharmacology, indications, use, and complications associated with Droperidol, and speculate on its future use in the Emergency Department.

Adverse drug reactions associated with antipsychotics, antidepressants, and mood stabilizers

This article on major ADRs associated with psychotropic agents has overviewed major side effects of conventional and novel medications. Nursing interventions that focus on prevention, early identification, accurate diagnosis and appropriate interventions are crucial to treatment outcomes.

Antipsychotic-related QTc prolongation, torsade de pointes and sudden death

Sudden unexpected deaths have been reported with antipsychotic use since the early 1960s. In some cases the antipsychotic may be unrelated to death, but in others it appears to be a causal factor. Antipsychotics can cause sudden death by several mechanisms, but particular interest has centred on torsade de pointes (TdP), a polymorphic ventricular arrhythmia that can progress to ventricular fibrillation and sudden death. The QTc interval is a heart rate-corrected value that represents the time between the onset of electrical depolarisation of the ventricles and the end of repolarisation. Prolongation of the QTc interval is a surrogate marker for the ability of a drug to cause TdP. In individual patients an absolute QTc interval of >500 msec or an increase of 60 msec from baseline is regarded as indicating an increased risk of TdP. However, TdP can occur with lower QTc values or changes. Concern about a relationship between QTc prolongation, TdP and sudden death applies to a wide range of drugs and has led to the withdrawal or restricted labelling of several. Among antipsychotics available in the UK, sertindole was voluntarily suspended, droperidol was withdrawn, and restricted labelling introduced for thioridazine and pimozide. The degree of QTc prolongation is dose dependent and varies between antipsychotics reflecting their different capacity to block cardiac ion channels. Significant prolongation is not a class effect. Among currently available agents, thioridazine and ziprasidone are associated with the greatest QTc prolongation. Virtually all drugs known to cause TdP block the rapidly activating component of the delayed rectifier potassium current (I(kr)). Arrhythmias are more likely to occur if drug-induced QTc prolongation coexists with other risk factors, such as individual susceptibility, presence of congenital long QT syndromes, heart failure, bradycardia, electrolyte imbalance, overdose of a QTc prolonging drug, female sex, restraint, old age, hepatic or renal impairment, and slow metaboliser status. Pharmacodynamic and pharmacokinetic interactions can also increase the risk of arrhythmias. Further research is needed to quantify the risk of sudden death with antipsychotics. The risk should be viewed in the context of the overall risks and benefits of antipsychotic treatment. It seems prudent, where possible, to select antipsychotics that are not associated with marked QTc prolongation. If use of a QTc-prolonging drug is warranted, then measures to reduce the risk should be adopted.

A comparison of the receptor binding and HERG channel affinities for a series of antipsychotic drugs

Many antipsychotic drugs produce QT interval prolongation on the electrocardiogram (ECG). Blockade of the human cardiac K(+) channel known as human ether-a-go-go-related gene (HERG) often underlies such clinical findings. In fact, HERG channel inhibition is now commonly used as a screen to predict the ability of a drug to prolong QT interval. However, the exact relationship between HERG channel blockade, target receptor binding affinity and clinical QT prolongation is not known. Using patch-clamp electrophysiology, we examined a series of seven antipsychotic drugs for their ability to block HERG, and determined their IC(50) values. We then compared these results to their binding affinities (K(i) values) for the dopamine D(2) receptor, the 5-HT(2A) receptor and, where available, to clinical QT prolongation data. We found that sertindole, pimozide and thioridazine displayed little (<10-fold) or no selectivity for dopamine D(2) or 5-HT(2A) receptors relative to their HERG channel affinities. This lack of selectivity likely underlies the significant QT interval prolongation observed with administration of these drugs. Of the other drugs tested (ziprasidone, quetiapine, risperidone and olanzapine), olanzapine displayed the greatest selectivity for dopamine D(2) and 5-HT(2A) receptor binding (100-1000-fold) compared to its HERG channel IC(50). We also compared these HERG channel IC(50) values to QT interval prolongation and plasma drug levels obtained in a recent clinical study. We found that the ratio of total plasma drug concentration to HERG IC(50) value was indicative of the degree of QT prolongation observed. Target receptor affinity and expected clinical plasma levels are important parameters to consider for the interpretation of HERG channel data.

Cardiotoxicity and prescription of thioridazine in New Zealand

OBJECTIVE

To review the production of cardiac arrhythmia by thioridazine, and consider the role of government regulation in light of antipsychotic prescribing trends in New Zealand.

METHODS

We conducted a focused literature review on psychotropic-induced cardiotoxicity, including mechanisms and incidence. In addition, we considered trends in antipsychotic prescription in New Zealand and decisions made by regulatory bodies in Australia, North America and the United Kingdom regarding restrictions on the prescription of thioridazine.

RESULTS

In general, the cardiotoxicity of antipsychotics, including thioridazine, relates to the ability of these drugs to antagonize voltage-sensitive potassium channels, and thereby prolong the QT interval. This action can lead to malignant arrhythmias in a very small proportion (< < 1%) of patients; the risk may be increased by other drugs or factors which prolong QT or inhibit the metabolism of thioridazine. A review of prescription doses and volumes in New Zealand indicates that thioridazine is prescribed mainly in low doses by non-specialists, and its use has been waning significantly over the past 2 years. These trends predate recent publicity regarding cardiotoxicity.

CONCLUSION

Recommendations regarding thioridazine use are presented. Although new patients should not receive this drug, existing patients benefiting from modest doses should not be denied access unless clear-cut risk factors for cardiotoxicity are evident.

The rise and withdrawal of droperidol

Predicting which patients will experience postoperative nausea and vomiting is difficult. Prophylactic antiemetic administration has been shown to reduce unplanned admission after day case surgery. In published comparative studies of antiemetic efficacy, droperidol has been considered to be the 'gold standard' against which other agents are measured. The recent withdrawal of droperidol due to reports of cardiac arrhythmias and the potential for sudden death has left a vacancy for a safe and effective antiemetic. This article explores the published literature for alternatives to droperidol as a single dose or prophylaxis in patient controlled analgesia devices.

Understanding and managing behavioural symptoms in Alzheimer's disease and related dementias: focus on rivastigmine

Behavioural and psychological symptoms of dementia (BPSD) are among the most distressing manifestations of dementia and result in considerable social and economic costs. Practical, non-pharmacological approaches such as environmental and behavioural changes may provide some benefit for patients in managing mild BPSD. In addition, various pharmacological approaches to treatment have been employed, such as neuroleptics and atypical antipsychotics, which differ in neurochemical target and clinical effectiveness. Growing evidence suggests that the neurobiological basis of BPSD in Alzheimer's disease (AD) and related dementias is a loss of cholinergic neurones and a resultant decline in acetylcholine (ACh) in brain regions which regulate behavioural and emotional responses, such as the limbic system. This cholinergic deficit can be partly corrected by inhibiting cholinesterase enzymes (ChEs). Studies of ChE inhibitors have shown positive effects to improve or stabilise existing BPSD and delay the emergence of new behavioural symptoms. In placebo-controlled studies, donepezil has reported efficacy in non-institutionalised moderate to moderately severe patients over a period of 24 weeks, but has failed to demonstrate efficacy in mild to moderate AD and in institutionalised patients with severe disease. Galantamine has been shown to delay the onset of BPSD in mild to moderate AD patients in one placebo-controlled study, and improve BPSD in a similar study of patients with cerebrovascular disease or probable vascular dementia. Studies with rivastigmine have shown efficacy in placebo-controlled studies of mild to moderately severe AD and in patients with Lewy body variant AD. Institutionalised patients with severe disease also show symptomatic benefits in BPSD with rivastigmine, resulting in a reduction in concomitant psychoactive medication use. Symptom complexes responding to ChE inhibitors appear to differ - all agents improve apathy, depression and anxiety, while rivastigmine additionally improves hallucinations and delusions, possibility as a result of dual inhibition of acetylcholinesterase and butyrylcholinesterase. The presence of hallucinations has been shown to predict response to rivastigmine. Accumulating data from studies of ChE inhibitors suggest that early intervention and long-term treatment, in addition to providing cognitive benefits, improves BPSD and offers potential to enhance quality of life. Differences seen between the agents in terms of efficacy in BPSD, tolerability and safety profiles may be the result of differences in neuropharmacological profiles.

The ABC of Alzheimer's disease: behavioral symptoms and their treatment

Behavioral and psychological symptoms of dementia (BPSD) are a common manifestation of Alzheimer's disease (AD) and other dementia syndromes. Patients experience prominent and multiple symptoms, which are both distressing and a source of considerable social, health, and economic cost. Development of symptoms is in part related to progressive neurodegeneration and cholinergic deficiency in brain regions important in the regulation of behavioral and emotional responses including the cortex, hippocampus, and limbic system. Cholinesterase (ChE) inhibitors offer a mechanism-based approach to therapy to enhance endogenous cholinergic neurotransmission. Studies using ChE inhibitors have demonstrated their clear potential to improve or stabilize existing BPSD. Differences have been noted between selective acetylcholinesterase (AChE) inhibitors (donepezil and galantamine) and dual ChE inhibitors (rivastigmine) in terms of treatment response. While donepezil has shown efficacy in moderate to severe noninstitutionalized AD patients, conflicting results have been obtained in mild to moderate patients and in nursing home patients. Galantamine has been shown to delay the onset of BPSD during a five-month study but has been otherwise poorly studied to-date. Both donepezil and galantamine have not as yet demonstrated efficacy in reducing psychotic symptoms or in reducing levels of concomitant psychotropic medication use. Studies with the dual ChE inhibitor rivastigmine in mild to moderately severe AD and in Lewy body dementia (LBD) have shown improvements in behavioral symptoms including psychosis. Improvements have been maintained over a period of up to two years. In addition, institutionalized patients with severe AD have shown symptomatic benefits with a reduction in the requirement for additional psychotropic drugs following treatment with rivastigmine. The psychotropic properties associated with rivastigmine may in part be mediated through effects on butyrylcholinesterase. Current treatment options are limited for patients with dementia syndromes other than AD. However, data concerning rivastigmine in patients with LBD and preliminary studies in Parkinson's disease dementia and vascular dementia suggest a role for ChE inhibitors across the spectrum of dementia syndromes. Finally, studies that incorporated a delayed start design demonstrate that ChE inhibitors may delay the progression of BPSD.

Evaluation of drug-induced QT interval prolongation: implications for drug approval and labelling

Assessment of proarrhythmic toxicity of newly developed drugs attracts significant attention from drug developers and regulatory agencies. Although no guidelines exist for such assessment, the present experience allows several key suggestions to be made and an appropriate technology to be proposed. Several different in vitro and in vitro preclinical models exist that, in many instances, correctly predict the clinical outcome. However, the correspondence between different preclinical models is not absolute. None of the available models has been demonstrated to be more predictive and/or superior to others. Generally, compounds that do not generate any adverse preclinical signal are less likely to lead to cardiac toxicity in humans. Nevertheless, differences in likelihood offer no guarantee compared with entities with a preclinical signal. Thus, the preclinical investigations lead to probabilistic answers with the possibility of both false positive and false negative findings. Clinical assessment of drug-induced QT interval prolongation is crucially dependent on the quality of electrocardiographic data and the appropriateness of electrocardiographic analyses. An integral part of this is a precise heart rate correction of QT interval, which has been shown to require the assessment of QT/RR relationship in each study individual. The numbers of electrocardiograms required for such an assessment are larger than usually obtained in pharmacokinetic studies. Thus, cardiac safety considerations need to be an integral part of early phase I/II studies. Once proarrhythmic safety has been established in phase I/II studies, large phase III studies and postmarketing surveillance can be limited to less strict designs. The incidence of torsade de pointes tachycardia varies from 1 to 5% with clearly proarrhythmic drugs (e.g. quinidine) to 1 in hundreds of thousands with drugs that are still considered unsafe (e.g. terfenadine, cisapride). Thus, not recording any torsade de pointes tachycardia during large phase III studies offers no guarantee, and the clinical premarketing evaluation has to rely on the assessment of QT interval changes. However, since QT interval prolongation is only an indirect surrogate of predisposition to the induction of torsade de pointes tachycardia, any conclusion that a drug is safe should be reserved until postmarketing surveillance data are reviewed. The area of drug-related cardiac proarrhythmic toxicity is fast evolving. The academic perspective includes identification of markers more focused compared with simple QT interval measurement, as well as identification of individuals with an increased risk of torsade de pointes. The regulatory perspective includes careful adaptation of new research findings.