Cisapride and QTc interval in children

QTc Interval Reference Values and Their (Non)-Maturational Factors in Neonates and Infants: A Systematic Review

QTc interval measurement is a widely used screening tool to assess the risk of cardiac diseases, arrhythmias, and is a useful biomarker for pharmacovigilance. However, the interpretation of QTc is difficult in neonates due to hemodynamic maturational changes and uncertainties on reference values. To describe trends in QTc values throughout infancy (1 year of life), and to explore the impact of (non)-maturational changes and medicines exposure, a structured systematic review (PROSPERO CRD42022302296) was performed. In term neonates, a decrease was observed over the first week of life, whereafter values increased until two months of age, followed by a progressive decrease until six months. A similar pattern with longer QTc values was observed in preterms. QTc is influenced by cord clamping, hemodynamic changes, therapeutic hypothermia, illnesses and sleep, not by sex. Cisapride, domperidone and doxapram result in QTc prolongation in neonates. Further research in this age category is needed to improve primary screening practices and QTcthresholds, earlier detection of risk factors and precision pharmacovigilance.

Increased risk of antipsychotic-related QT prolongation during nighttime: a 24-hour holter electrocardiogram recording study

Most antipsychotic agents can cause QT prolongation, which causes torsades de pointes. The QT interval in healthy subjects is longer during nighttime than during daytime. The QT interval of patients treated with antipsychotics may be prolonged during nighttime, and the effects of antipsychotics on the QT interval may differ between antipsychotics. This study investigated the circadian dynamics of the QT interval in patients treated with antipsychotics and healthy controls, using a 24-hour Holter electrocardiogram in a clinical setting. Sixty-six patients with a diagnosis of schizophrenia that were treated with risperidone or olanzapine and 40 healthy volunteers were enrolled. The QT intervals were corrected using the Fridericia formula (QTcF = QT / RR). Mean ± SD nighttime QTcFs were 411.6 ± 29.0, 395.9 ± 21.2, and 387.8 ± 19.0 milliseconds (ms) in the risperidone, olanzapine, and control groups, respectively. The mean daytime QTcFs were 397.7 ± 23.4, 392.4 ± 18.9, and 382.6 ± 17.3 ms, respectively. The mean nighttime QTcF of the risperidone group was significantly longer than that of the olanzapine and control groups, although there was no significant difference in the mean daytime QTcF between the risperidone and olanzapine groups. The current study used 24-hour Holter electrocardiograms to reveal significantly longer QT intervals in the risperidone group especially during nighttime. In clinical practices, evaluations of the QT interval have been conducted over short periods in the daytime, but it is believed that such methods may not be able to fully elucidate the effects of antipsychotics on the QT interval.

Application of the Bradford Hill Criteria to Assess the Causality of Cisapride-Induced Arrhythmia

INTRODUCTION

The Bradford Hill criteria are a widely used, useful tool for the assessment of biomedical causation. We have examined their application to pharmacovigilance using the example of cisapride-induced QTc interval prolongation/arrhythmia.

METHODS

A literature search was conducted using MEDLINE, EMBASE, Reactions Weekly and regulatory websites to identify evidence for the association between cisapride and QTc interval prolongation/arrhythmia that had been published in the English language. Two hundred and five publications were identified as being potentially suitable for the study. After excluding irrelevant articles, studies on high-risk populations and review articles, 70 publications were assessed using the Bradford Hill criteria. These included 24 case reports, case series or spontaneous report summaries; eight epidemiological studies; 22 clinical studies; and 16 experimental (in vivo and in vitro) publications.

RESULTS

The most compelling evidence for an association between cisapride use and QTc interval prolongation/arrhythmia came from case/spontaneous reports and biological plausibility. Considering the rare incidence of serious cardiac events, these criteria formed the basis for the strength of the association. The number of reports from different populations showed consistency. Specificity was supported by clinical and cardiographic characterisation of the events. There were temporal relationships between the events and the initiation of cisapride treatment, increases in the dosage and the receipt of interacting medications. The relationships between the adverse events and the latter two factors exhibited biological gradients. Experimental evidence could be found from biological models, as well as reports of positive dechallenge and/or rechallenge found in individual patients. Cisapride was found to bind the human ether-a-go-go-related gene (HERG) potassium channel, which provides a plausible mechanism for QTc interval prolongation/arrhythmia. Other QTc interval-prolonging/arrhythmic drugs that also bind to HERG provided an analogy for cisapride causing QTc interval prolongation/arrhythmia via this mechanism. The evidence provided by clinical studies was inconsistent, and epidemiological studies failed to demonstrate an association. Nevertheless, this did not prevent the assessment of causation.

DISCUSSION

This study showed how different types of evidence found in pharmacovigilance can be evaluated using the Bradford Hill criteria. Further work is required to examine how the criteria can be applied to different types of adverse events and how they may be applied to pharmacovigilance.

Development of a safe and effective pediatric dosing regimen for sotalol based on population pharmacokinetics and pharmacodynamics in children with supraventricular tachycardia

OBJECTIVES

The objective of this study was to develop age-specific dosage guidelines for sotalol in children with supraventricular tachycardia (SVT) based on a population pharmacokinetic covariate analysis, clinical trial simulations, and pharmacodynamics.

BACKGROUND

A rapid onset of an effective and safe antiarrhythmic sotalol therapy, especially for infants and neonates, is frequently delayed because of age-dependent interpatient variability in pharmacokinetics and pharmacodynamics.

METHODS

Pediatric patients with SVT (mean age 3.51 years [range 0.03 to 17 years]) were analyzed after oral sotalol doses of 1.0 to 9.9 mg/kg/day using population pharmacokinetic analysis and clinical trial simulation (n = 76), pharmacokinetic/pharmacodynamic modeling for QT interval prolongation (n = 32), and for the concentration-antiarrhythmic-response relationship (n = 15).

RESULTS

Inter-individual differences in oral clearance and volume of distribution could largely be attributed to size and weight differences, with an additional age effect on clearance in children younger than one year. Neonates showed a higher sensitivity toward QTc interval prolongation compared with older patients. In a subgroup of 15 patients, one-half of the patients converted into sinus rhythm at sotalol trough levels of 0.4 mug/ml and more than 95% at 1.0 mug/ml. Dosing recommendations derived for different age groups based on these findings were starting dose and target dose of 2 and 4 mg/kg/day for neonates, 3 and 6 mg/kg/day for infants and children <6 years, and 2 and 4 mg/kg/day for children >6 years.

CONCLUSIONS

This study provides an example for rational drug dosage in children that copes with interpatient variability and can be easily switched to an individually guided therapy based on effective sotalol trough levels.

Inhibition of L-type Ca(2+) current in Guinea pig ventricular myocytes by cisapride

The effect of cisapride on L-type Ca(2+) current (I(Ca,L)) was studied in guinea pig ventricular myocytes using a whole-cell voltage-clamp technique and a conventional action potential recording method. Myocytes were held at -40 mV, and internally dialyzed and externally perfused with Na(+)- and K(+)-free solutions; cisapride elicited a concentration-dependent block of peak I(Ca,L), with a half-maximum inhibition concentration (IC(50)) of 46.9 microM. There was no shift in the reversal potential, nor any change in the shape of the current-voltage relationship of I(Ca,L) in the presence of cisapride. Inhibition of cisapride was not associated with its binding to serotonin or to alpha-adrenergic receptors because ketanserin, SB203186, and prazosin had no effect on the inhibitory action of cisapride on I(Ca,L). Cisapride elicited a tonic block and a use-dependent block of I(Ca,L). These blocking effects were voltage dependent as the degree of inhibition at -40 mV was greater than that at -70 mV. Cisapride shifted the steady-state inactivation curve of I(Ca,L) in the negative direction, but had no effect on the steady-state activation curve. Cisapride also delayed the kinetics of recovery of I(Ca,L) from inactivation. At a slow stimulation frequency (0.1 Hz), the action potential duration in guinea pig papillary muscles showed biphasic effects; it was prolonged by lower concentrations of cisapride, but shortened by higher concentrations. These findings suggest that cisapride preferentially binds to the inactivated state of L-type Ca(2+) channels. The inhibitory effect of cisapride on I(Ca,L) might play an important role in its cardiotoxicity under pathophysiological conditions, such as myocardial ischemia.

24-Hour Electrocardiogram before and during Cisapride Treatment in Neonates and Infants

We studied prospectively the effects of cisapride on heart rate and rhythm using standard ECG and 24-hour ECG recordings in term and preterm neonates and infants. We studied subjects with gastroesophageal reflux disease (apparent life-threatening events, apneas, bradycardias) before and 3 days after starting cisapride (0.8 mg/kg/day in 4 doses). We performed standard ECGs for determination of corrected Q-T interval (QTc) and Q-T dispersion (QTd) and 24-hour ECG recordings for analysis of heart rate, heart rate variability, and heart rhythm. Fourteen term and 17 preterm subjects (gestational age range 28-36 weeks) were studied at a median chronological age of 29 (range 3-132) days. Cisapride significantly increased the QTc in preterm infants (before vs. after: 408 +/- 7 vs. 433 +/- 7 ms, p = 0.001). Two preterm and 1 term infant had a QTc >450 ms before cisapride. Four preterm (4/15 = 27%) and 2 term (2/13 = 15%) subjects had a QTc >450 ms on cisapride. After cisapride the QTd remained normal, and no relevant arrhythmias were documented on Holter recordings. Cisapride significantly decreased peak and mean heart rates of all study subjects without affecting the heart rate variability, while it increased the minimal heart rate of preterm infants only (before vs. after: 66 +/- 5 vs. 78 +/- 5 bpm, p = 0.02). The maximally measured R-R intervals (pauses) decreased after cisapride in preterm infants (before vs. after: 1.33 +/- 0.2 s vs. 1.05 +/- 0.2 s, p = 0.04). Although cisapride did cause a significant prolongation of the ventricular action potential duration in preterm infants, the QTd remained unaffected, and no clinically relevant arrhythmias were documented in this small sample. On the other hand, cisapride had a direct lowering effect on the maximal and mean heart rates of both term and preterm infants, while the drug increased the minimal heart rate and reduced the severity of bradycardia episodes in preterm infants.

Efficacy and tolerability of cisapride in children

As gastro-oesophageal reflux disease (GORD) in infants and children is a motility disorder which differs in pathophysiology and clinical course from GORD in adults, prokinetics should be considered the drug of choice in certain circumstances. Indeed, cisapride may result in improvement of feeding tolerance in premature infants. Cisapride has a better tolerability profile than a 'wait-and-see-if-improvement-comes-spontaneously' policy or the other therapeutic options available. A careful and critical review of published data suggests that cisapride may have a QTc-prolonging effect. However, provided the precautions for cisapride administration are followed, the QTc-prolonging effect remains consistently without clinically relevant adverse effects. Correct dosage and avoidance of concurrent treatment with macrolides and/or azoles are the most relevant tolerability recommendations in children. Although there is a need for a prokinetic with better efficacy, cisapride is currently the prokinetic with the best benefit-to-risk ratio available. Thus, withdrawal of cisapride would result in a significantly increased risk for severe complications in infants and children with GORD or other gastrointestinal motility disorders such as chronic intestinal pseudo-obstruction, gastroparesis and feed intolerance in premature infants.