The QT interval and the atypical antipsychotic, sertindole

Augmenting clozapine with sertindole: a double-blind, randomized, placebo-controlled study

Clozapine augmentation with antipsychotic drugs is widely used despite sparse evidence supporting this strategy. Sertindole is a nonsedating atypical antipsychotic drug with low affinity for cholinergic receptors, which makes it potentially suitable for augmentation of clozapine. The study design was a 12-week, double-blind, randomized, placebo-controlled study including patients with International Statistical Classification of Diseases, 10th Revision schizophrenia (F20.0-F20.3) and treated with clozapine for at least 6 months who had not achieved sufficient response. Patients were randomized 1:1 to either sertindole 16 mg or placebo, and assessment was done at baseline and after 6 and 12 weeks. Assessment included the Positive and Negative Syndrome Scale, Clinical Global Impression, Udvalg for Kliniske Undersøgelser, World Health Organization Quality of Life Brief, Drug Attitude Inventory, fasting glucose, lipids, and electrocardiogram. Clozapine augmentation with sertindole was not superior to placebo regarding total score or subscale score of the Positive and Negative Syndrome Scale, Clinical Global Impression, World Health Organization Quality of Life Brief, or Drug Attitude Inventory. No increased adverse effects compared with placebo were found. Four patients randomized to sertindole experienced a significant worsening of psychosis, and 2 of them required psychiatric admission. Metabolic parameters were unchanged during the study, but augmentation of clozapine with sertindole was associated with a 12-millisecond (SD, 20-millisecond) QTc prolongation compared with 0 millisecond (SD, 20 milliseconds) in the placebo group (P < 0.03). Augmentation with sertindole showed no benefits compared with placebo. Psychiatrists should be aware that augmentation might not add any benefits for the patients and in some cases worsen psychosis.

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.

The potential relationship between QTc interval prolongation and ziprasidone treatment: three cases

QTc interval prolongation may appear as a consequence of both typical and atypical antipsychotic treatments. Ziprasidone, which is effective in treating schizophrenia, is associated with QTc prolongation. Although the prolongation of QTc with ziprasidone treatment is often pronounced, there is a scarce number of cases reported about the relationship between ziprasidone and QTc prolongation. Of the three cases presented in this case series, two cases showed values exceeding 0.50 s with ziprasidone treatment.

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.

A new class of selective, non-basic 5-HT2A receptor antagonists

Based on an existing series of 5-HT2A receptor ligands containing a basic nitrogen, we designed a non-basic lead that had reduced affinity for both the 5-HT2A receptor and the IKr potassium channel. The present paper describes the development of this lead to a novel series of non-basic piperidine sulfonamides and amides that have high affinity for the 5-HT2A receptor, whilst maintaining excellent selectivity over off target activities such as the IKr channel. This work has shown that the proposed pharmacophore model for the 5-HT2A receptor which suggests that a basic nitrogen is required for the binding of ligands is questionable.

Electrophysiologic properties and antiarrhythmic actions of a novel antianginal agent

Ranolazine is a novel antianginal agent capable of producing anti-ischemic effects at plasma concentrations of 2 to 6 microM without a significant reduction of heart rate or blood pressure. This review summarizes the electrophysiologic properties of ranolazine. Ranolazine significantly blocks I(Kr) (IC(50) = 12 microM), late I(Na), late I(Ca), peak I(Ca), I(Na-Ca) (IC(50) = 5.9, 50, 296, and 91 microM, respectively) and I(Ks) (17% at 30 microM), but causes little or no inhibition of I(to) or I(K1). In left ventricular tissue and wedge preparations, ranolazine produces a concentration-dependent prolongation of action potential duration (APD) in epicardium, but abbreviation of APD of M cells, leading to either no change or a reduction in transmural dispersion of repolarization (TDR). The result is a modest prolongation of the QT interval. Prolongation of APD and QT by ranolazine is fundamentally different from that of other drugs that block I(Kr) and induce torsade de pointes in that APD prolongation is rate-independent (ie, does not display reverse rate-dependent prolongation of APD) and is not associated with early after depolarizations, triggered activity, increased spatial dispersion of repolarization, or polymorphic ventricular tachycardia. Torsade de pointes arrhythmias were not observed spontaneously nor could they be induced with programmed electrical stimulation in the presence of ranolazine at concentrations as high as 100 microM. Indeed, ranolazine was found to possess significant antiarrhythmic activity, acting to suppress the arrhythmogenic effects of other QT-prolonging drugs. Ranolazine produces ion channel effects similar to those observed after chronic exposure to amiodarone (reduced late I(Na), I(Kr), I(Ks), and I(Ca)). Ranolazine's actions to reduce TDR and suppress early after depolarization suggest that in addition to its anti-anginal actions, the drug possesses antiarrhythmic activity.

Ziprasidone in the management of schizophrenia : the QT interval issue in context

Ziprasidone is a new atypical antipsychotic recently marketed in a number of countries. Its main advantage over other atypical and typical drugs is its low propensity for causing weight gain. However, ziprasidone has been shown to prolong to some extent the cardiac corrected QT (QTc) interval, a property shared by a number of other antipsychotics. Prolongation of the QTc interval is linked to the ventricular tachyarrhythmia torsade de pointes, which is occasionally fatal, although the precise association between QTc changes and risk of sudden cardiac death has not been determined. QTc prolongation is certainly linked in some way to an increased risk of sudden cardiac death, and this may explain the recent, somewhat preliminary, reports of increased risk associated with use of some antipsychotics. Ziprasidone prolongs QTc to a moderate degree, though to a greater extent than quetiapine, risperidone, olanzapine and haloperidol. There is also preliminary evidence that ziprasidone blocks the delayed potassium rectifier channel in cardiac cells. Because of this, and despite the fact that no increased risk of arrhythmia or sudden death has been demonstrated for ziprasidone, some caution is required. Ziprasidone should be avoided in patients with some types of cardiac disease and with uncontrolled electrolyte disturbance. Coprescription of ziprasidone with other drugs that prolong the QT interval should be avoided where possible. When cross-tapering with other antipsychotics, care should be taken to avoid high total load of antipsychotics, and cross-tapering with drugs known to prolong QT interval at normal clinical doses should be avoided. Under most clinical circumstances, however, ziprasidone may be safely used without ECG monitoring or other special precautions. Its effect on QT interval and possible effect on risk of arrhythmia should be balanced with the observation that the drug has a more favourable effect on bodyweight and glucose homeostasis (and so perhaps cardiac risk) than many other antipsychotics.

Antipsychotics and QT prolongation

OBJECTIVE

To evaluate literature relating to cardiac QT prolongation and the use of antipsychotic drugs.

METHOD

Literature searches of EMBASE, Medline, PsychLIT were performed in December 2001 and reference sections of retrieved papers scrutinized for further relevant reports.

RESULTS

The Cardiac QTc interval is difficult to measure precisely or accurately but appears to be a useful predictor of risk of dysrhythmia (specifically torsade de pointes) and sudden death. It is less clear that drug-induced QTc prolongation gives rise to similar risks but data are emerging, linking antipsychotic use to increased cardiac mortality. Many antipsychotics have been clearly associated with QTc prolongation. Methodological considerations arguably preclude assuming that any antipsychotic is free of the risk of QTc prolongation and dysrhythmia.

CONCLUSION

Available data do not allow assessment of relative or absolute risk of dysrhythmia or sudden death engendered by antipsychotics but caution is advised. Risk of dysrhythmia can very probably be reduced by careful prescribing of antipsychotics in low doses in simple drug regimens which avoid metabolic interactions. Electrocardiographic monitoring may also help to reduce risk but review by specialist cardiologist may be necessary.

Neuropharmacological profile of an atypical antipsychotic, NRA0562

Schizophrenia is a serious and disabling psychiatric disorder affecting approximately 1% of the world's population. A new generation of atypical antipsychotics has been introduced over the past decade. These atypical antipsychotics have comparable or greater efficacy than traditional antipsychotics in the treatment of the psychotic symptoms of schizophrenia and a much improved neurologic side effect profile. This paper reviews the pharmacological efficacy and safety of a potential atypical antipsychotic, NRA0562. NRA0562 has a high affinity for dopamine D1, D2L, D4.2, 5-HT2A receptors as well as alpha1-adrenoceptors, and has a moderate affinity for H1 receptors. NRA0562 strongly binds to 5-HT2A receptors and alpha1-adrenoceptors in the frontal cortex, its binding to striatal D2 receptors is weaker, similar to that of clozapine. NRA562 displayed potent antipsychotic activities in animal models of schizophrenia, such as methamphetamine (MAP)-induced hyperactivity, apomorphine-induced disruption of pre-pulse inhibition and conditioned avoidance test. NRA0562 is more potent in reversing the inhibitory effects of MAP at A10 than at A9 dopamine neurons. It increased Fos-like immunoreactivity in the nucleus accumbens more effectively than in the dorsolateral striatum, indicating that NRA0562 has the profile of an atypical antipsychotic. In vivo assays for extrapyramidal side effect liability showed that NRA0562 has a low rate of neurological side effects. Thus, NRA0562 may have unique antipsychotic activity with a lower propensity for extrapyramidal side effects.

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.

Electrophysiologic characterization of the antipsychotic drug sertindole in a rabbit heart model of torsade de pointes: low torsadogenic potential despite QT prolongation

There is growing concern that antipsychotic drugs that prolong the QT interval almost always increase the risk for patients to develop life-threatening ventricular tachyarrhythmias (VTs) of the torsade de pointes type. We therefore sought to compare the electrophysiologic effects of the psychotropic agent sertindole, which prolongs cardiac repolarization by inhibiting the rapid component of the delayed rectifier potassium current (I(Kr)) but has a low torsadogenic potential to the antiarrhythmic agent dl-sotalol. In 18 Langendorff-perfused rabbit hearts, sotalol (10 microM, n = 8) and sertindole (0.5, 1.0, and 1.5 microM; n = 10) led to significant and comparable QT prolongation. In the presence of sotalol, torsade de pointes reproducibly occurred in atrioventricular node-blocked hearts after lowering the potassium concentration to 1.5 mM. High doses of sertindole (1.5 microM) only caused monomorphic VT (n = 4) and nonsustained polymorphic VT (n = 2) in the presence of QRS prolongation. Multiple simultaneous epi- and endocardial monophasic action potentials and a volume-conducted ECG demonstrated widening of the T/U wave, early afterdepolarizations, and increased dispersion of repolarization in the presence of dl-sotalol. In contrast to sotalol, QT and monophasic action potential prolongation were cycle length-independent in the presence of sertindole. Sertindole had no significant effect on transmural or interventricular dispersion of repolarization. Early afterdepolarizations did not occur. Despite comparable QT prolongation, sertindole did not display the proarrhythmic profile typical of other blockers of I(Kr) such as dl-sotalol. It is likely that a different mode of interaction between sertindole and the channel and/or additional pharmacological effects of sertindole, e.g., its ability to inhibit I(Na) and/or its ability to block alpha(1)-receptors, play a role.

A randomized, double-blind controlled comparison of nefazodone and paroxetine in the treatment of depression: safety, tolerability and efficacy in continuation phase treatment

We investigated the safety, tolerability and efficacy of nefazodone and paroxetine in the continuation phase of treatment of depression. The study comprised a double-blind, parallel-group comparison over 4 months, of patients who had previously improved following random allocation to nefazodone or paroxetine during an 8-week acute treatment study. Assessments included Clinical Global Impression Scales, Hamilton Rating Scales for Depression and Anxiety, Montgomery-Asberg Depression Rating Scale and the Patient Global Assessment Scale, in addition to a review of reported adverse events, vital sign measurements, electrocardiograms and clinical laboratory tests. One hundred and eight patients participated in the continuation study (53 received paroxetine, 55 nefazodone) and 73 completed treatment. No clinically relevant differences in antidepressant efficacy were seen. Headache and somnolence were the most common reported adverse events in both treatment groups. Both nefazodone and paroxetine maintain their efficacy in continuation treatment, and both are generally well tolerated.

3-(4-Fluoropiperidin-3-yl)-2-phenylindoles as high affinity, selective, and orally bioavailable h5-HT(2A) receptor antagonists

The development of very high affinity, selective, and bioavailable h5-HT(2A) receptor antagonists is described. By investigation of the optimal position for the basic nitrogen in a series of 2-phenyl-3-piperidylindoles, it was found that with the basic nitrogen at the 3-position of the piperidine it was not necessary to further substitute the piperidine in order to obtain good binding at h5-HT(2A) receptors. This meant the compounds no longer had high affinity at the IKr potassium channel, an issue with previous series of 2-aryl-3-(4-piperidyl)indoles. Improvements could be made to oral bioavailability in this series by reduction of the pK(a) of the basic nitrogen, by adding a fluorine atom to the piperidine ring, leading to 3-(4-fluoropiperidin-3-yl)-2-phenyl-1H-indole (17). Metabolic studies with this compound identified oxidation at the 6-position of the indole as a major route in vitro and in vivo in rats. Blocking this position with a fluorine atom led to 6-fluoro-3-(4-fluoropiperidin-3-yl)-2-phenyl-1H-indole (22), an antagonist with 0.06 nM affinity for h5-HT(2A) receptors, with bioavailability of 80% and half-life of 12 h in rats.