Facts, fancies and follies of drug-induced QT/QTc interval shortening

A thorough QTc study to evaluate the effects of oral rilzabrutinib administered alone and with ritonavir in healthy subjects

This study aimed to define the clinically relevant supratherapeutic dose of rilzabrutinib, an oral Bruton tyrosine kinase (BTK) inhibitor, and evaluate potential effects of therapeutic and supratherapeutic exposures on cardiac repolarization in healthy subjects. This was a two‐part phase I study (anzctr.org.au ACTRN12618001036202). Part A was a randomized, open‐label, three‐period, single‐dose crossover study (n = 12) with rilzabrutinib 100 mg ± ritonavir 100 mg or rilzabrutinib 1200 mg. Part B was a randomized, double‐blind, placebo‐controlled, four‐way, single‐dose crossover study (n = 39) with matched placebo, rilzabrutinib 400 mg ± ritonavir 100 mg, or moxifloxacin (positive control). Primary objectives: part A – pharmacokinetics (PK) of rilzabrutinib ± ritonavir, safety, and optimal dose for Part B; Part B – effect of rilzabrutinib therapeutic and supratherapeutic concentration on electrocardiogram (ECG) parameters. ECGs and PK samples were serially recorded before and post‐dose. In part A, rilzabrutinib 100 mg + ritonavir led to 17‐fold area under the concentration–time curve (AUC_0–∞) and 7‐fold maximum plasma concentration (C_max) increases over rilzabrutinib alone. Rilzabrutinib 1200 mg was discontinued due to mild‐to‐moderate gastrointestinal intolerance. In Part B, rilzabrutinib 400 mg + ritonavir increased rilzabrutinib mean AUC_0–∞ from 454 to 3800 ng h/mL and C_max from 144 to 712 ng/mL. The concentration–QTc relationship was slightly negative, shallow (−0.01 ms/ng/mL [90% CI −0.016 to −0.001]), and an effect >10 ms on QTcF could be excluded within the observed range of plasma concentrations, up to 2500 ng/mL. Safety was similar to other studies of rilzabrutinib. In conclusion, rilzabrutinib, even at supratherapeutic doses, had no clinically relevant effects on ECG parameters, including the QTc interval.

A Phase 1 Clinical Study Evaluating the Effects of Cenobamate on the QT Interval

Cenobamate is an antiseizure medication for uncontrolled focal seizures. This thorough QT study assessed the effects of therapeutic and supratherapeutic cenobamate doses (maximum recommended dose, 400 mg/day) on correct QT interval (QTc) in healthy adults (N = 108) randomly assigned to 1 of 3 treatments: (A) cenobamate (days 1-63) up-titrated by 50-mg increments weekly to a 200 mg/day therapeutic dose (day 35) and then by 100 mg weekly to a 500 mg/day supratherapeutic dose (day 63), with placebo-moxifloxacin (days -1 and 64); (B) moxifloxacin 400 mg (day -1; positive control), placebo-cenobamate (days 1-63), and placebo-moxifloxacin (day 64); and (C) placebo-moxifloxacin (day -1), placebo-cenobamate (days 1-64), and moxifloxacin 400 mg (day 64). The primary end point was baseline-adjusted, placebo-corrected QTc (ΔΔQTcF; corrected for heart rate [HR] by Fridericia's method) with cenobamate 200 and 500 mg/day. Baseline electrocardiographic parameters were balanced across groups. Mean ΔΔQTcF was negative throughout for cenobamate doses (largest: day 35, -10.8 milliseconds; day 63, -18.4 milliseconds). Based on concentration-QTc analysis, ∆∆QTcF effect was predicted as -9.85 and -17.14 milliseconds at mean peak plasma levels of therapeutic (200 mg/day; 23.06 μg/mL) and supratherapeutic (500 mg/day; 63.96 μg/mL) doses. Cenobamate had no clinically relevant prolonging effect on electrocardiographic parameters (eg, PR, QRS); HR effects were similar to placebo. Cenobamate showed slight dose-related shortening of QTc, but to a degree not known to be clinically relevant (no reductions ≤340 milliseconds). Cenobamate had no clinically relevant effects on HR or electrocardiographic parameters and no QTc-prolonging effect at therapeutic/supratherapeutic doses. Cenobamate is contraindicated in patients with short-QT syndrome and caution should be used when coadministering with drugs that shorten QT interval.

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

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

Confirmation of the cardiac safety of nolasiban in a randomised cohort of healthy female volunteers

Nolasiban is an orally active oxytocin receptor antagonist being developed to increase the efficiency of assisted reproductive technologies. This study evaluated the pharmacokinetics, pharmacodynamics, and cardiac safety of nolasiban in 45 healthy women of child-bearing age. Nolasiban was administered in a fasted state with a standardised lunch served 4.5 h post-dose. Concentration-effect modelling was used to assess the effect of two dosages of nolasiban (900 mg and 1800 mg) on QTc following single-dose administration. We found no significant change in QTc at all tested dosages. Two-sided 90% confidence intervals of geometric mean C_max for estimated QTc effects of nolasiban were below the threshold of regulatory concern. The sensitivity of the assay to detect small changes in QTc was confirmed by a significant shortening of QTc between 2 and 4 h after consumption of a meal, which served to validate the model. Independent of the nolasiban assessment, this study also explored the effects of sex hormones on ECG parameters, especially QT subintervals. We found a significant relationship between JTpc and oestradiol. Heart rate was negatively correlated with progesterone. This study confirms the cardiovascular safety of nolasiban and describes relationships of sex hormones and ECG parameters.

The Use of Voltage Sensitive Dye di-4-ANEPPS and Video-Based Contractility Measurements to Assess Drug Effects on Excitation-Contraction Coupling in Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes

ABSTRACT

Because cardiotoxicity is one of the leading causes of drug failure and attrition, the design of new protocols and technologies to assess proarrhythmic risks on cardiac cells is in continuous development by different laboratories. Current methodologies use electrical, intracellular Ca2+, or contractility assays to evaluate cardiotoxicity. Increasingly, the human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are the in vitro tissue model used in commercial assays because it is believed to recapitulate many aspects of human cardiac physiology. In this work, we demonstrate that the combination of a contractility and voltage measurements, using video-based imaging and fluorescence microscopy, on hiPSC-CMs allows the investigation of mechanistic links between electrical and mechanical effects in an assay design that can address medium throughput scales necessary for drug screening, offering a view of the mechanisms underlying drug toxicity. To assess the accuracy of this novel technique, 10 commercially available inotropic drugs were tested (5 positive and 5 negative). Included were drugs with simple and specific mechanisms, such as nifedipine, Bay K8644, and blebbistatin, and others with a more complex action such as isoproterenol, pimobendan, digoxin, and amrinone, among others. In addition, the results provide a mechanism for the toxicity of itraconazole in a human model, a drug with reported side effects on the heart. The data demonstrate a strong negative inotropic effect because of the blockade of L-type Ca2+ channels and additional action on the cardiac myofilaments. We can conclude that the combination of contractility and action potential measurements can provide wider mechanistic knowledge of drug cardiotoxicity for preclinical assays.

No QTc Prolongation With Zanubrutinib: Results of Concentration-QTc Analysis From a Thorough QT Study in Healthy Subjects

This thorough QT (TQT) study evaluated the effect of zanubrutinib on electrocardiogram (ECG) parameters by using concentration‐QTc (C‐QTc) analysis as the primary analysis for this study. Part A of the study determined the safety and tolerability of a single supratherapeutic dose of zanubrutinib (480 mg) in healthy volunteers. Part B was a randomized, blinded, placebo‐controlled and positive‐controlled, four‐way crossover, TQT study of single therapeutic (160 mg) and supratherapeutic (480 mg) doses of zanubrutinib, placebo, and open‐label moxifloxacin 400 mg. Thirty‐two participants received at least 1 dose of zanubrutinib, and 26 participants completed all 4 periods. Zanubrutinib did not have any effect on heart rate or cardiac conduction (pulse rate, QRS interval, or T‐wave morphology) and was generally well‐tolerated. Using C‐QTc analysis, the predicted placebo‐corrected change‐from‐baseline QT interval using Fridericia’s formula (ΔΔQTcF) was −3.4 msec (90% confidence interval: −4.9 to −1.9 msec) at peak concentrations of the 480 mg dose. A QT effect (ΔΔQTcF) exceeding 10 msec could be excluded within the observed concentration range at 160 and 480 mg doses. Assay sensitivity was established by moxifloxacin with 90% lower bound exceeding 5 msec. Implementing a C‐QTc analysis prospectively in this TQT study resulted in a substantially smaller sample size to maintain a similar study power as shown in the traditional time‐point analysis. A single 160‐mg or 480‐mg zanubrutinib dose did not prolong the QTc interval or have any other clinically relevant effects on ECG parameters.

Basic Cardiac Electrophysiology and Common Drug-induced Arrhythmias

Drugs can be a double-edged sword, providing the benefit of symptom alleviation and disease modification but potentially causing harm from adverse cardiac arrhythmic events. Proarrhythmia is the ability of a drug to cause an arrhythmia, the number one reason for drugs to be withdrawn from the patient. Drug-induced arrhythmias are defined as the production of de novo arrhythmias or aggravation of existing arrhythmias, as a result of previous or concomitant pharmacologic treatment. This review summarizes normal cardiac cell and tissue functioning and provides an overview of drugs that effect cardiac repolarization and the adverse effects of commonly administered antiarrhythmics.

Effect of Retosiban on Cardiac Repolarization in a Randomized, Placebo- and Positive-controlled, Crossover Thorough QT/QTc Study in Healthy Men and Women

PURPOSE

Retosiban is a small molecule oxytocin receptor antagonist that is under evaluation in clinical studies for treatment of spontaneous preterm labor. A Thorough QT/QTc study was conducted to evaluate the effect of retosiban on cardiac repolarization according to International Conference on Harmonization E14 guidance. This was a randomized, placebo- and positive-controlled, single-dose, crossover study of healthy men and women.

METHODS

All study participants received a 100 mg dose of retosiban (therapeutic target exposure), a 800 mg dose of retosiban (supratherapeutic target exposure), a 400 mg dose of moxifloxacin (positive control), and placebo with an appropriate washout. Holter monitoring data at baseline (predose) and at 13 subsequent time points during the next 24 hours were extracted and manually read by a central ECG reader who was blinded to the treatment assignment and corrected for heart rate by using the Fridericia formula (QTcF). A linear exposure-QTc response model was developed: ΔΔQTcF=RI+Cp,R⋅RS+MI+Cp,M⋅MS, where RI and MI are intercept terms for retosiban and moxifloxacin, respectively, RS and MS are slope terms for retosiban and moxifloxacin, respectively, and Cp,R and Cp,M are plasma concentrations for retosiban and moxifloxacin, respectively.

FINDINGS

A total of 52 healthy men (n = 27) and women (n = 25), with a mean age of 32 years, were enrolled in the study, and 43 (83%) completed all treatment periods and assessments. Mean placebo-corrected change from baseline QT (ΔΔQTcF) for the 2 retosiban dose groups revealed statistically significant decreases in ΔΔQTcF between 2 and 3 hours after administration, reaching a value of -2.5 msec for both retosiban dose groups. The 400 mg moxifloxacin group had a statistically significant increase in the ΔΔQTcF value at 0.75 hours after administration, reaching a maximal increase of 11.10 msec at 4 hours after administration. Results of the exposure-QTc response modeling revealed that there was no significant effect of retosiban on the ΔΔQTcF at therapeutic exposures. For the supratherapeutic exposure of retosiban, there was a slight negative effect, with a mean decrease of -3.05 msec. The moxifloxacin arm had a mean increase in ΔΔQTcF of 10.7 msec.

IMPLICATIONS

At therapeutic and supratherapeutic exposures, retosiban had no significant effect on cardiac repolarization, as estimated by the ΔΔQTcF. However, both doses of retosiban had a minor shortening effect. This is not considered to be clinically significant. CLINICALTRIALS.

GOV IDENTIFIER

NCT01702376.

Pharmacological and electrophysiological characterization of AZSMO-23, an activator of the hERG K(+) channel

BACKGROUND AND PURPOSE

We aimed to characterize the pharmacology and electrophysiology of N-[3-(1H-benzimidazol-2-yl)-4-chloro-phenyl]pyridine-3-carboxamide (AZSMO-23), an activator of the human ether-a-go-go-related gene (hERG)-encoded K(+) channel (Kv 11.1).

EXPERIMENTAL APPROACH

Automated electrophysiology was used to study the pharmacology of AZSMO-23 on wild-type (WT), Y652A, F656T or G628C/S631C hERG, and on other cardiac ion channels. Its mechanism of action was characterized with conventional electrophysiology.

KEY RESULTS

AZSMO-23 activated WT hERG pre-pulse and tail current with EC50 values of 28.6 and 11.2 μM respectively. At 100 μM, pre-pulse current at +40 mV was increased by 952 ± 41% and tail current at -30 mV by 238 ± 13% compared with vehicle values. The primary mechanism for this effect was a 74.5 mV depolarizing shift in the voltage dependence of inactivation, without any shift in the voltage dependence of activation. Structure-activity relationships for this effect were remarkably subtle, with close analogues of AZSMO-23 acting as hERG inhibitors. AZSMO-23 blocked the mutant channel, hERG Y652A, but against another mutant channel, hERG F656T, its activator activity was enhanced. It inhibited activity of the G628C/S631C non-inactivating hERG mutant channel. AZSMO-23 was not hERG selective, as it blocked hKv 4.3-hKChIP2.2, hCav 3.2 and hKv 1.5 and activated hCav 1.2/β2/α2δ channels.

CONCLUSION AND IMPLICATIONS

The activity of AZSMO-23 and those of its close analogues suggest these compounds may be of value to elucidate the mechanism of type 2 hERG activators to better understand the pharmacology of this area from both a safety perspective and in relation to treatment of congenital long QT syndrome.

No evidence of QT prolongation with supratherapeutic doses of aleglitazar

Aleglitazar is a dual peroxisome proliferator-activated receptor (PPAR)-α/γ agonist in clinical development, designed to offer a balanced activation of PPAR-α and PPAR-γ. A phase 2 trial has demonstrated improvements in dyslipidemia and glycemic control and reduction of cardiovascular risk markers in patients with type 2 diabetes mellitus treated with aleglitazar. This study evaluated whether supratherapeutic doses of aleglitazar affect cardiac repolarization, as detected by changes in the QT interval.Healthy subjects were randomized to receive single oral doses of placebo, 300 μg aleglitazar, 3000 μg aleglitazar, and 400 mg moxifloxacin, in 1 of 4 sequences. Triplicate 12-lead electrocardiogram measurements were recorded predose and regularly (0.75-72 hours) after each treatment. The primary outcome was measurement of QT interval using a study-specific correction factor for heart rate.Administration of aleglitazar (300 μg and 3000 μg) did not cause any significant QT prolongation and after aleglitazar treatment any mean increases from placebo were <5 msec, at all time points. There was a trend for aleglitazar to cause a small dose-dependent decrease in QT interval using a study-specific correction factor for heart rate. The incidence of adverse events was similar with aleglitazar (18%-20%) and placebo (26%).Single supratherapeutic doses of aleglitazar are not associated with prolongation of the QT interval corrected for heart rate.

The DPP-4 inhibitor linagliptin does not prolong the QT interval at therapeutic and supratherapeutic doses

AIM

To evaluate the potential effects of therapeutic and supratherapeutic doses of linagliptin (BI 1356) on the QT/QT(c) interval in healthy subjects.

METHODS

The study was a randomized, double-blind, placebo-controlled, four-period crossover study using single oral doses of linagliptin (5 mg and 100 mg), moxifloxacin (400 mg) and placebo. Electrocardiogram (ECG) profiles using triplicates of 12-lead 10-s ECGs were digitally recorded pre-dose and after drug administration. The mean change from baseline (MCfB) of the individually heart rate corrected QT interval (QT(c) I) between 1 and 4 h postdrug administration was the primary end point. Blood samples to measure plasma concentrations of linagliptin and its main metabolite were also obtained.

RESULTS

Forty-four Caucasian subjects (26 male) entered the study and 43 subjects completed the study as planned in the protocol. Linagliptin was not associated with an increase in the baseline-adjusted mean QT(c) I, at any time point. The placebo-corrected MCfB of QT(c) I was -1.1 (90% CI -2.7, 0.5) ms and -2.5 (-4.1, -0.9) ms for linagliptin 5 mg and 100 mg, respectively, thus within the non-inferiority margin of 10 ms according to ICH E14. Linagliptin was well tolerated; the assessment of ECGs and other safety parameters gave no clinically relevant findings at either dose tested. Maximum plasma concentrations after administration of 100-mg linagliptin were ∼24-fold higher than those observed previously for chronic treatment with the therapeutic 5-mg dose. Assay sensitivity was confirmed by a placebo-corrected MCfB of QT(c) I with moxifloxacin of 6.9 (90% CI 5.4, 8.5) ms.

CONCLUSIONS

Therapeutic and significantly supratherapeutic exposure to linagliptin is not associated with QT interval prolongation.

Thorough QT Studies: Questions and Quandaries

The International Conference on Harmonisation E14 Guidance was successful in largely standardizing the conduct of the so-called thorough QT/QTc studies (TQTS). Nevertheless, there is still a spectrum of frequently encountered problems with details of design, conduct and interpretation of TQTS. Several of these challenges are reviewed here, starting with explaining that the TQTS goal is only to identify drugs for which the proarrhythmic risk might be considered excluded for the purposes of regulatory benefit-risk assessment. Suggestions are made on how to categorize and quantify or exclude proarrhythmic risk if the TQTS is positive. There is a conceptual need for TQTS, and this is discussed, together with reasons why restricted clinical registries cannot prove the absence of proarrhythmic liability of any drug. Appropriate drug doses investigated in TQTS should be derived from the maximum clinically tolerable dose rather than from the known or expected therapeutic dose. With the help of concentration-QTc modelling, the standard therapeutic dose can be omitted from TQTS, especially if the study is expected to be negative. Conditions for single-dose TQTS acceptability are reviewed. The role of the so-called positive control is assessed, contrasting the role of a same-class comparator for the investigated drug. A single 400 mg dose of moxifloxacin is advocated as the present 'gold standard' assay sensitivity test. The necessity of careful placebo control is explained and the frequency of ECG assessments is considered. The central tendency and outlier analyses are discussed, together with the correct approaches to baseline adjustment. The review concludes that the design and interpretation of TQTS must not be approached with mechanistic stereotypes, and highlights the importance of relating the QTc changes to drug plasma levels.

Reducing QT liability and proarrhythmic risk in drug discovery and development

Drug-induced torsades de pointes (TdP), a rare, life-threatening, polymorphic, ventricular tachycardia associated with prolongation of the QT interval, has been the main safety reason for the withdrawal of medicines from clinical use over the last decade. Most often, drugs that prolong the action potential and delay ventricular repolarization do so through blockade of outward (repolarizing) currents, predominantly the rapid delayed rectifying potassium current, I(Kr). While QT interval prolongation is not a safety concern per se, in a small percentage of people, it has been associated with TdP, which either spontaneously terminates or degenerates into ventricular fibrillation. Furthermore, recent data suggest that shortening of the QT interval may also be a new safety issue waiting to surface. This review article summarizes the presentations given at a symposium entitled 'Reducing QT liability and proarrhythmic risk in drug discovery and development', which was part of the Federation of the European Pharmacological Societies congress, Manchester, UK, 13-17 July 2008. The objective of this symposium was to assess the effects of implementing the latest regulatory guidance documents (International Conference on Harmonization S7A/B and E14), as well as new scientific and technical trends on the ability of the pharmaceutical industry to reduce and manage the QT liability and associated potential proarrhythmic risk, and contribute to the discovery and development of safer medicines. This review outlines the key messages from communications presented at this symposium and attempts to highlight some of the key challenges that remain to be addressed.