Drugs, QT interval prolongation and ICH E14: the need to get it right.

Regulatory concerns on the ability of an ever-increasing number of non-cardiovascular drugs to prolong the corrected QT (QTc) interval and induce potentially fatal ventricular tachyarrhythmias have culminated in initiatives to harmonise internationally the regulatory guidance on strategies by which to evaluate new drugs for this liability. The International Conference on Harmonisation (ICH) has released consensus texts for clinical (ICH topic E14) and non-clinical (ICH topic S7B) strategies as regulatory drafts for wider consultation. Draft ICH E14 calls for a clinical 'thorough QT/QTc study' (typically in healthy volunteers) for new drugs with systemic bioavailability, regardless of the non-clinical data. This indifference to non-clinical data has sparked off a major debate, even among the regulators. The 'thorough QT/QTc study' is intended to determine whether a drug has a threshold pharmacological effect on cardiac repolarisation, as detected by QT/QTc prolongation, and proposes the use of a positive control to validate the study. The guideline recommends exploration of the effect of concentrations that are higher than those achieved following the anticipated therapeutic doses and, consequently, a negative 'thorough QT/QTc study', even in the presence of non-clinical data of concern, will almost always allow standard collection of on-therapy ECGs. The proposed threshold of a 5 ms increase in mean placebo-corrected QTc interval for designating a study as positive for an effect, with all its implications for subsequent development of the drug and its regulatory assessment and labelling, has also generated a controversy. This paper provides an overview commentary on some contentious or ambiguous aspects of draft ICH E14 with a view to stimulating a debate and inviting scientifically supported comments from stakeholders in order to ensure that the application of the ICH E14 strategy, when finalised and adopted, does not result in either restriction in the use (or even rejection) of a potentially beneficial drug or approval of an otherwise hazardous drug without the restrictions required to promote its safe use.     

QTc interval prolongation and antipsychotic drug treatments: focus on sertindole

Since the 1960s, physicians have been aware of electrocardiographic (ECG) abnormalities and cases of sudden death associated with the use of antipsychotic drugs in patients with schizophrenia. Explanations for such deaths have traditionally focused on drug-induced prolongation of the QT interval leading to the development of life-threatening ventricular arrhythmias such as torsade de pointes (TdP). It is now apparent that most conventional and atypical antipsychotics can cause dose-related prolongation of the corrected QT interval (QTc), although there are important differences in the potency of individual agents. This review discusses potential mechanisms underlying QTc prolongation and arrhythmogenesis and examines the evidence for a relationship between antipsychotic drugs and prolongation of the QTc interval. New electrophysiological and epidemiological data are presented which suggest there may not be a clear-cut cause-effect relationship between QTc prolongation and the development of ventricular tachyarrhythmias for all atypical antipsychotics. For at least one of these agents (sertindole), counterbalancing mechanisms may act to reduce the risk of proarrhythmic activity arising as a result of QTc prolongation.     

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.     

Risperidone, QTc interval prolongation, and torsade de pointes: a systematic review of case reports

Rationale

A recent publication asserted that even low-dose risperidone may induce corrected QT (QTc) interval prolongation up to 500 ms without drug-induced I_Kr blockade. We seek to better understand the complexity of any link between risperidone-induced/associated QTc interval prolongation and torsade de pointes (TdP).

Objectives

The objective of this study is to systematically analyze all available case reports of risperidone, QTc interval prolongation, and/or TdP.

Method

We identify case reports using PubMed, Medline, EMBASE, and Cochrane.

Results

Of the 15 cases found, nine were adult women (ages 31, 33, 34, 37, 47, “elderly”, 77, 84, and 87 years) and one was a teenager. There were four men (ages 28, 29, 29, and 46 years) and one preadolescent boy. Besides risperidone administration or overdose, traditional risk factors for QTc interval prolongation and TdP included female sex (n?=?10), older age (n?=?4), heart disease (n?=?3), hypokalemia (n?=?2), bradycardia (n?=?1), liver disease (n?=?1), QTc interval prolonging drugs other than risperidone (n?=?8), and metabolic inhibitors (n?=?2). TdP occurred in four cases. Six patients died, and three deaths were probably related to TdP.

Conclusion

Risperidone (when properly prescribed in patients free of other risk factors for QTc interval prolongation and TdP) is a relatively safe drug. Conventional statistics can neither predict the individual patient who will experience TdP nor determine the relationship of drug dose to QTc interval prolongation and TdP. Narrative medicine using a case report format appears to be an alternative and valuable additional approach to advance our understanding of this relationship and to reduce risks.     

Draft ICH guideline S7B: guideline on safety pharmacology studies for assessing the potential for delayed ventricular repolarization (QT interval prolongation) by human pharmaceuticals

Nonclinical assessment of potential of QT interval prolongation caused by non-antiarrhythmic drugs has been an issue for drug development because QT interval prolongation increases the risk of ventricular tachyarrhythmia, including torsade de pointes when combined with other risk factors. However, there is no scientific consensus on approaches and no international consensus on regulatory recommendations. This guideline is being developed to provide the general nonclinical testing strategy for evaluating the potential risk of QT prolongation and presents some major principles for in vitro and in vivo electrophysiology studies. The basis of this guideline is the integrated risk assessment that provides overall evaluations based on nonclinical study results and chemical/pharmacological class information to predict the potential of a test substance to prolong QT interval in humans (i.e., evidence of risk) and that contributes clinical study design and interpretation of clinical results. Safety margins are also components of integrated risk assessment. Since this guideline addresses a field of research that is in a state of rapid evolution, the proposed concept for evidence of risk and safety margins needs to be further refined based on the data being collected by international initiatives. In this article, the draft S7B guideline is outlined.     

Detection of QTc interval prolongation using jacket telemetry in conscious non-human primates: comparison with implanted telemetry

Background and Purpose: During repeat-dose toxicity studies, ECGs are collected from chemically or physically-restrained animals over a short timeframe. This is problematic due to cardiovascular changes caused by manual restraint stress and anesthesia, and limited ECG sampling. These factors confound data interpretation, but may be overcome by using a non-invasive jacket-based ECG collection (JET). The current study investigated whether a jacketed external telemetry system could detect changes in cardiac intervals and heart rate in non-human primates (NHPs), previously implanted with a PCT transmitter.Experimental Approach: Twelve male cynomolgus monkeys were treated weekly with vehicle or sotalol (8, 16, 32 mg kg⁻¹) p.o. ECGs were collected continuously for 24 hours, following treatment, over 4 weeks. A satellite group of six NHPs was used for sotalol toxicokinetics.Key Results: Sotalol attained C_max values 1–3 hours after dosing, and exhibited dose-proportional exposure. In jacketed NHPs, sotalol dose-dependently increased QT/QTc intervals, prolonged PR interval, and reduced heart rate. Significant QTc prolongation of 27, 54 and 76 msec was detected by JET after 8, 16, and 32 mg kg⁻¹ sotalol, respectively, compared with time-matched vehicle-treated animals. Overall, JET-derived PR, QT, QTc intervals, QRS duration, and heart rate correlated well with those derived from PCT.Conclusions and Implications: The current findings clearly support the use of JET to quantify cardiac interval and rhythm changes, capable of detecting QTc prolongation caused by sotalol. JET may be a preferred method compared to restraint-based ECG because high-density ECG sampling can be collected in unstressed conscious monkeys, over several weeks.     

ICH E14:一项新的评价新药研发中药物临床心脏安全性的国际药政法规

2005年5月，有关在临床研究中如何监督新药对心脏安全性的措施，经国际协调会议（ICH）讨论并通过了一项新的工作指南，即ICH协调性三方指南：非抗心律不齐药物的致QT／QTc间期延长和致心律失常的临床评价。本文概述并讨论了该指南要点，以期望对相关新药安全性监督起到一定指导作用。     

Assessing QT/QTc interval prolongation with concentration-QT modeling for Phase I studies: impact of computational platforms,model structures and confidence interval calculation methods

Modeling the relationship between drug concentrations and heart rate corrected QT interval (QTc) change from baseline (C-?QTc), based on Phase I single ascending dose (SAD) or multiple ascending dose (MAD) studies, has been proposed as an alternative to thorough QT studies (TQT), in assessing drug-induced QT prolongation risk. The present analysis used clinical SAD, MAD and TQT study data of an experimental compound, AZD5672, to evaluate the performance of: (i) three computational platforms (linear mixed-effects modeling implemented via PROC MIXED in SAS, as well as in R using LME4 package and linear quantile mixed models (LQMM) implemented via LQMM package; (ii) different model structures with and without treatment- or time-specific intercepts; and (iii) three methods for calculating the confidence interval (CI) of QTc prolongation (analytical and bootstrap methods with fixed or varied geometric mean concentrations). We show that treatment- and time-specific intercepts may need to be included into C-?QTc modeling through PROC MIXED or LME4, regardless of their statistical significance. With the intersection union test (IUT) in the TQT study as a reference for comparison, inclusion of these intercepts increased the feasibility for C-?QTc modelling of SAD or MAD to reach the same conclusion as the IUT analysis based on TQT study. Compared to PROC MIXED or LME4, the LQMM method is less dependent on inclusion of treatment- or time-specific intercepts, and the bootstrap CI calculation methods provided higher likelihood for C-?QTc modeling of SAD and MAD studies to reach the same conclusion as the IUT based on the TQT study.     

1例胺碘酮合用莫西沙星致QTc间期延长并发尖端扭转型室速的病例分析

目的:探讨QTc延长并发尖端扭转型室速的原因,为临床用药的安全性提供参考。方法:临床药师参与1例胺碘酮合用莫西沙星致QTc间期延长并发尖端扭转型室速的治疗,分析不良反应发生的原因及处理方法。结果:此次不良反应可能与胺碘酮和莫西沙星有关,该患者危险因素较多,临床用药时应加强用药安全的监督。结论:临床使用胺碘酮联用莫西沙星时,临床药师应掌握药物相互作用,加强药学监护,提高用药安全性。     

Clinical evaluation of QT/QTc prolongation and proarrhythmic potential for nonantiarrhythmic drugs: the International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use E14 guideline

Proarrhythmias due to drug-induced QT prolongation are the second most common cause for drug withdrawal and have caused increasing concern. Two new International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) guidelines were recently endorsed in which nonclinical (S7B) and clinical (E14) methodologies are discussed and guidance is given to the industry. This commentary describes the key components of the E14 document, the impact of nonclinical testing on the clinical program, the thorough QT study, and the impact of its result on late-stage development. The studies described in S7B and E14 will contribute to a better understanding of the link between nonclinical assays and QT prolongation in humans. Differences in interpretation among individual regulators in the major regions with respect to measures proposed in the E14 guideline might impact regional regulatory decisions. These differences include the value of nonclinical assays for the subsequent clinical testing and how predictive a negative thorough QT study result is for proarrhythmic risk in patients.     

QTc interval prolongation by fexofenadine in healthy human volunteers and its correlation with plasma levels of fexofenadine: A demonstration of anticlockwise hysteresis

Aim:

The study was designed to establish relationship between the plasma concentration and QTc interval prolonging effect of fexofenadine and demonstrate the phenomenon of anticlockwise hysteresis.

Materials and Methods:

Six subjects were given fexofenadine 60 mg tablet orally under stable conditions, and their drug concentrations were measured at regular intervals. At predetermined time, their ECGs were recorded. Data were analyzed and plotted graphically.

Design and Setting:

Randomized parallel design, single group study conducted at clinical research organization of Ahmadabad.

Results:

In all subjects time taken for maximum plasma concentration of fexofenadine (T_max) was around 3 h and the value of average maximum plasma concentration was 460.63 ng/mL, the effect of fexofenadine on the heart (measured as QTc interval prolongation) was maximum (E_max) after 6 h and average QTc interval was 469.75 ms. Thus, the time to maximum concentration of fexofenadine did not match with the maximum effect on the heart as measured by QTc interval.

Conclusion:

The relationship between the drug concentration and drug effect on the heart are at two different time scales. It can be understood by two-compartment model of pharmacokinetics, and this retardation or lagging of an effect behind the concentration is known as hysteresis. The increase of QTc was not beyond 500 ms and not sustained, demonstrating overall cardiac safety of fexofenadine.     

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.     

ILSI-HESI cardiovascular safety subcommittee dataset: an analysis of the statistical properties of QT interval and rate-corrected QT interval (QTc)

INTRODUCTION: The Health and Environmental Sciences Institute of the International Life Sciences Institute (ILSI/HESI) Cardiovascular Safety Subcommittee outlined a set of in vivo telemetry studies to determine how well this preclinical model identified compounds known to cause torsades de pointes (TdP) and prolong QT interval in humans. In the original analysis of these data, QT, QTcB (Bazett model), QTcF (Fridericia model), and QTcQ (animal-specific model) were evaluated. We further evaluate the statistical properties of these measurements, using a method that can properly account for the sources of variability in the dataset. METHODS: The ILSI/HESI telemetry studies were conducted as a double Latin square design where eight dogs each received a vehicle control and three dose levels of a compound on four separate dosing days. We statistically analyzed the QT/QTc intervals using a repeated measures analysis of covariance and evaluate the powers for QT, QTcF and QTcQ based on simulations. RESULTS: The analyses for QTcF and QTcB intervals show that all six compounds which were known to cause TdP in humans were identified as positive and all six compounds known to be free of TdP events in their clinical use had no statistically significant treatment-related effects, while the analyses for QTcQ identified all positive compounds except pimozide. The power analysis shows that the method can detect a 7% increment of QT, a 5% increment of QTcF, and a 4% increment of QTcQ, with greater than 80% of power when n=8. DISCUSSION: We describe a repeated measures procedure to perform statistical analysis of covariance on Latin square designs and show that it can be used to detect meaningful changes in the analysis of QT/QTc intervals.     

Pharmacovigilance during the pre-approval phases: an evolving pharmaceutical industry model in response to ICH E2E, CIOMS VI, FDA and EMEA/CHMP risk-management guidelines.

Pharmacovigilance science has traditionally been a discipline focussed on the postmarketing or post-authorisation period, with due attention directed towards pre-clinical safety data, clinical trials and adverse events. As the biological sciences have evolved, pharmacovigilance has slowly shifted toward earlier, proactive consideration of risks and potential benefits of drugs in the pre- and peri-approval stages of drug development, leading to a maturing of drug safety risk management. Further advances in biology, pharmacology and improvements in computational applications to medicine have led to the development of more complex medicines previously unobtainable and have also permitted a more thorough assessment of risks and potential benefits even earlier in the development process. Elevated public concern with the safety of more sophisticated medicines, combined with new science, have led pharmaceutical innovators, regulators and healthcare professionals to collaborate to develop guidelines, which drive enhanced pharmacovigilance and safety risk management earlier in drug development. In this paper, we review international guidelines on pharmacovigilance planning applicable to the pre-approval phases of medicines development and provide author opinion on these guidelines' potential drug safety implications. We discuss the possible evolution of a pharmaceutical industry model to respond to these guidelines; a view on multidisciplinary safety management teams is provided to encourage refinement of safety-signal identification and risk assessment early in drug development and to communicate important safety concerns to internal research efforts, patients, investigators and regulators. We further describe these functions in the context of the complexities of vulnerable populations, including the example of medicines research for paediatric populations. We also discuss the special role of epidemiology in pre-approval drug development and the impact on epidemiological science of changes to the pharmacovigilance paradigm.     

The use of electrocardiograms in clinical trials: a public discussion of the proposed ICH E14 regulatory guidance. April 11-12, 2005, Bethesda, MD, USA

This meeting, jointly sponsored by the FDA, Drug Information Association and Heart Rhythm Society, examined crucial issues on nonclinical and clinical evaluation of the potential of new drugs to prolong the QT interval of an electrocardiogram (ECG). It gathered approximately 350 attendees from pharmaceutical industry, academia, core ECG analysis laboratories, regulatory agencies (FDA, European Medicines Agency, Japanese Ministry of Health, Labour and Welfare, and Health Canada) and the International Conference on Harmonisation (ICH). Key issues discussed included the reliability of the S7B guideline strategy, design and usefulness of the 'thorough QT/QTc study' recommended by ICH E14 guideline, choice of 5 ms QTc prolongation as a threshold for regulatory concern, ECG reading, and statistical analysis. This report is restricted to the two main presentations dealing with the predictability of nonclinical tests for clinical outcomes--one defending the prognostic value of nonclinical tests and the other, from the FDA, which casts reservations on the predictive value of nonclinical studies. Commentary on the recent finalisation of ICH S7B and E14 guidelines are also provided.     

Shortening of donepezil-induced QTc prolongation with a change in the interacting drug, after electrocardiograph monitoring by community pharmacists: a case report

We used a mobile electrocardiograph to manage the adverse effects and interactions of drugs, especially QT-prolonging drugs, in a community pharmacy setting. We report the case of a patient in whom the risk of drug-induced torsades de pointes (TdP) was lowered, after monitoring by community pharmacists. Case: An 80-year-old woman was under donepezil (5 mg/d) therapy for Alzheimer's disease and also taking other drugs that interact with donepezil, namely, benidipine (8 mg/d) and atorvastatin (10 mg/d). The patient was visited almost every month, and an electrocardiogram was usually obtained. QTc prolongation (avg. 470±9 ms) was observed in the first to third tests. Her doctor was informed about these results and the risk factors (advanced age, gender, and drugs interactions (benidipine and atorvastatin)) associated with TdP and asked to respond promptly since several cases of donepezil-induced TdP have been reported. As a result, benidipine was replaced with amlodipine, while the remaining drugs were continued. After the change, a significant decrease in QTc values were observed in the fourth to seventh tests (avg. 441±9 ms, p=0.010), thereby indicating a decrease in TdP risk. The Drug Interaction Probability Scale (object drug, donepezil; precipitant drug, benidipine) score was +6 (probable). Thus, QTc shortening was a result of differences in donepezil-benidipine and donepezil-amlodipine interactions.     

Inhaled anti-infective chemotherapy for respiratory tract infections: Successes,challenges and the road ahead

One of the most common causes of illnesses in humans is from respiratory tract infections caused by bacterial, viral or fungal pathogens. Inhaled anti-infective drugs are crucial for the prophylaxis and treatment of respiratory tract infections. The benefit of anti-infective drug delivery via inhalation is that it affords delivery of sufficient therapeutic dosages directly to the primary site of infection, while minimizing the risks of systemic toxicity or avoiding potential suboptimal pharmacokinetics/pharmacodynamics associated with systemic drug exposure. This review provides an up-to-date treatise of approved and novel developmental inhaled anti-infective agents, with particular attention to effective strategies for their use, pulmonary pharmacokinetic properties and safety.