A randomized, placebo-controlled, four-period crossover, definitive QT study of the effects of APF530 exposure, high-dose intravenous granisetron, and moxifloxacin on QTc prolongation

Background

Regulatory concern about potential QT-interval prolongation by serotonin-receptor antagonist antiemetics prompted product-label changes. The first-generation serotonin-receptor antagonist granisetron is available in oral (PO), intravenous (IV), and transdermal formulations. APF530 is a formulation that provides sustained release of granisetron when administered as a single subcutaneous (SC) injection. The Phase I study reported here evaluated effects of APF530 on electrocardiographic intervals.

Methods

This single-site, double-blind, placebo-controlled, four-period crossover trial randomized healthy men and women to receive varying sequences of APF530 1 g SC, granisetron 50 μg/kg IV, moxifloxacin 400 mg PO, and placebo. Subjects were assessed for 49 hours after each treatment. The primary objective was to evaluate differences between baseline-adjusted, heart rate-corrected QT-interval change using the Fridericia rate correction (dQTcF) for APF530 1 g SC and placebo. Electrocardiograms were performed at various times throughout the assessment period. Pharmacokinetics and safety were evaluated.

Results

The upper one-sided 95% confidence interval (CI) for mean baseline-adjusted dQTcF at each post-dose time point between APF530 and placebo excluded 10 ms, indicating that APF530 1 g SC had no clinically significant effect on QTcF. Maximum observed QTcF change was 4.15 ms (90% CI, 0.94 to 7.36) at Hour 3. No clinically significant changes in other electrocardiogram intervals were observed. APF530 SC pharmacokinetics were as expected, with slow absorption (maximum plasma concentration 35.8 ng/mL, median time to maximum plasma concentration 11.1 hours) and slow elimination (mean half-life 18.6 hours; systemic clearance 20.2 L/hour) of granisetron versus the expected early peak concentration and elimination of granisetron IV. APF530 SC was well tolerated. Adverse events, most commonly constipation and SC injection-site reactions, were generally mild and quickly resolved.

Conclusion

APF530 1 g SC did not induce clinically significant QTcF interval prolongation or changes in the other electrocardiogram intervals, and was well tolerated at twice the recommended dose.

Electrocardiographic and cardiovascular diagnostic characteristics of patients receiving long-term opioid therapy for pain

OBJECTIVE

To examine cardiovascular and electrocardiogram (ECG) abnormalities seen in patients with chronic pain receiving long-term opioid therapy and to compare them with findings in normal subjects.

SETTING

Clinical pharmaceutical drug trial in a phase I pharmacology unit (normal subjects) and multiple phase 2b study sites (pain patients).

PATIENTS

Four hundred sixty-one pain patients with constipation due to long-term opioid therapy who were screened for a clinical trial of an investigational treatment for opioid-induced constipation.

INTERVENTIONS

None; all data used in this study were obtained prior to drug treatment.

MAIN OUTCOME MEASURES

This is a retrospective analysis of ECG abnormalities and clinical cardiovascular abnormalities in study participants compared with those in a normal reference group of 36,999 subjects.

RESULTS

Numerical ECG values were modestly but not clinically significantly different in the pain patients requiring opioids (mean heart rate +1.5 BPM, PR +5.2 milliseconds, QRS -4.7 milliseconds, and QT corrected for heart rate using the Fridericia formula +7.2 milliseconds). The largest difference in ECG diagnoses between the two groups was a fivefold greater incidence of previous myocardial infarction in the pain patient group (4.1 percent vs 0.8 percent). In addition, 50 percent of the pain patient group had a clinical cardiovascular diagnosis.

CONCLUSIONS

Patients with significant chronic pain requiring opioids have underlying clinical disorders that may be associated with abnormal cardiovascular physiology and ECGs. Clinicians who manage patients with chronic pain should be aware of the higher incidence of cardiovascular disease in this group.

Use and cardiovascular safety of transdermal and other granisetron preparations in cancer management

5-HT3 antagonists have been available as oral and intravenous preparations for decades. The availability more recently of transdermal granisetron and the anticipated availability of a subcutaneous granisetron preparation have provided helpful alternatives to patients, and these preparations have been shown to have less potential to prolong QT than other drugs in the class.

Cardiac imaging approaches to evaluate drug-induced myocardial dysfunction

The ability to make informed benefit-risk assessments for potentially cardiotoxic new compounds is of considerable interest and importance at the public health, drug development, and individual patient levels. Cardiac imaging approaches in the evaluation of drug-induced myocardial dysfunction will likely play an increasing role. However, the optimal choice of myocardial imaging modality and the recommended frequency of monitoring are undefined. These decisions are complicated by the array of imaging techniques, which have varying sensitivities, specificities, availabilities, local expertise, safety, and costs, and by the variable time-course of tissue damage, functional myocardial depression, or recovery of function. This White Paper summarizes scientific discussions of members of the Cardiac Safety Research Consortium on the main factors to consider when selecting nonclinical and clinical cardiac function imaging techniques in drug development. We focus on 3 commonly used imaging modalities in the evaluation of cardiac function: echocardiography, magnetic resonance imaging, and radionuclide (nuclear) imaging and highlight areas for future research.

Pharmacokinetics and repolarization effects of intravenous and transdermal granisetron

PURPOSE

The need for greater clarity about the effects of 5-HT(3) receptor antagonists on cardiac repolarization is apparent in the changing product labeling across this therapeutic class. This study assessed the repolarization effects of granisetron, a 5-HT(3) receptor antagonist antiemetic, administered intravenously and by a granisetron transdermal system (GTDS).

EXPERIMENTAL DESIGN

In a parallel four-arm study, healthy subjects were randomized to receive intravenous granisetron, GTDS, placebo, or oral moxifloxacin (active control). The primary endpoint was difference in change from baseline in mean Fridericia-corrected QT interval (QTcF) between GTDS and placebo (ddQTcF) on days 3 and 5.

RESULTS

A total of 240 subjects were enrolled, 60 in each group. Adequate sensitivity for detection of QTc change was shown by a 5.75 ms lower bound of the 90% confidence interval (CI) for moxifloxacin versus placebo at 2 hours postdose on day 3. Day 3 ddQTcF values varied between 0.2 and 1.9 ms for GTDS (maximum upper bound of 90% CI, 6.88 ms), between -1.2 and 1.6 ms for i.v. granisetron (maximum upper bound of 90% CI, 5.86 ms), and between -3.4 and 4.7 ms for moxifloxacin (maximum upper bound of 90% CI, 13.45 ms). Day 5 findings were similar. Pharmacokinetic-ddQTcF modeling showed a minimally positive slope of 0.157 ms/(ng/mL), but a very low correlation (r = 0.090).

CONCLUSION

GTDS was not associated with statistically or clinically significant effects on QTcF or other electrocardiographic variables. This study provides useful clarification on the effect of granisetron delivered by GTDS on cardiac repolarization.

Effects of Physicochemical Factors and Bacterial Colony Morphotype on Association of Vibrio vulnificus with Hemocytes of Crassostrea virginica

Vibrio vulnificus is a naturally occurring marine bacterium that causes invasive disease of immunocompromised humans following the consumption of raw oysters. It is a component of the natural microbiota of Gulf Coast estuaries and has been found to inhabit tissues of oysters, Crassostrea virginica (Gmelin 1791). The interaction of V. vulnificus with oyster host defenses has not been reported in detail. We examined the interaction of V. vulnificus with phagocytic oyster hemocytes as a function of time, temperature, bacterial concentration, pretreatment with hemolymph, and V. vulnificus translucent and opaque colony morphotypes. Within these experimental parameters, the results showed that the association of V. vulnificus with hemocytes increased with time, temperature, and initial V. vulnificus/hemocyte ratio. Pretreatment of V. vulnificus with serum or an increased serum concentration did not enhance V. vulnificus-hemocyte associations, a result suggesting the absence of opsonic activity. More than 50% of hemocytes bound the translucent, avirulent morphotype, whereas 10 to 20% were associated with the opaque, virulent form, a result indicating that the degree of encapsulation was related to resistance to phagocytosis, as previously described for mammalian phagocytes. Understanding these cellular interactions may, in part, explain the persistence of V. vulnificus in oyster tissues and the ecology of V. vulnificus in estuarine environments.

Evaluation of ventricular arrhythmias in early clinical pharmacology trials and potential consequences for later development

This white paper, prepared by members of the Cardiac Safety Research Consortium, discusses several important issues regarding the evaluation of ventricular arrhythmias in early clinical pharmacology trials and their potential consequences for later clinical drug development. Ventricular arrhythmias are infrequent but potentially important medical events whose occurrence in early clinical pharmacology trials can dramatically increase safety concerns. Given the increasing concern with all potential safety signals and the resultant more extensive electrocardiographic monitoring of subjects participating in early phase trials, an important question must be addressed: Are relatively more frequent observations of ventricular arrhythmias related simply to more extensive monitoring, or are they genuinely related to the drug under development? The discussions in this paper provide current thinking and suggestions for addressing this question.

Pharmacokinetics and pharmacodynamics of three moxifloxacin dosage forms: implications for blinding in active-controlled cardiac repolarization studies

Moxifloxacin is used in thorough QT studies to assess sensitivity for detection of an increase in QTc. Moxifloxacin is usually over-encapsulated for blinding. However, there is concern that over-encapsulation alters its pharmacokinetics. In a 4-arm, randomized crossover study, 22 volunteers received over-encapsulated moxifloxacin, over-encapsulated placebo, bare moxifloxacin, and intravenous (IV) moxifloxacin. Placebo capsules and IV infusions were administered so that treatments in each arm, except for bare moxifloxacin, were indistinguishable. Pharmacokinetics of the oral treatments were found to be nearly identical and to meet Food and Drug Administration criteria for bioequivalency. Relative to the IV infusion administered over 1 hour, the tablet formulation was bioequivalent to total exposure but not peak exposure maximum plasma concentration, which was lower by 22%. Median time to maximum plasma concentration of the IV infusion was 1.00 hour. A 2-compartment model with oral absorption and linear elimination adequately described the observed moxifloxacin data. Changes in QTcF mirrored the pharmacokinetic changes, and there was a linear relationship between plasma concentration of moxifloxacin and change in QTcF. A 2-stage infusion scheme for IV moxifloxacin mimics the oral plasma concentration versus time curve. Over-encapsulation of moxifloxacin did not alter its peak or total systemic exposures or pharmacodynamics after oral administration.

Automated QT analysis that learns from cardiologist annotations

BACKGROUND

Reliable, automated QT analysis would allow the use of all the ECG data recorded during continuous Holter monitoring, rather than just intermittent 10-second ECGs.

METHODS

BioQT is an automated ECG analysis system based on a Hidden Markov Model, which is trained to segment ECG signals using a database of thousands of annotated waveforms. Each sample of the ECG signal is encoded by its wavelet transform coefficients. BioQT also produces a confidence measure which can be used to identify unreliable segmentations. The automatic generation of templates based on shape descriptors allows an entire 24 hours of QT data to be rapidly reviewed by a human expert, after which the template annotations can automatically be applied to all beats in the recording.

RESULTS

The BioQT software has been used to show that drug-related perturbation of the T wave is greater in subjects receiving sotalol than in those receiving moxifloxacin. Chronological dissociation of T-wave morphology changes from the QT prolonging effect of the drug was observed with sotalol. In a definitive QT study, the percentage increase of standard deviation of QT(c) for the standard manual method with respect to that obtained with BioQT analysis was shown to be 44% and 30% for the placebo and moxifloxacin treatments, respectively.

CONCLUSIONS

BioQT provides fully automated analysis, with confidence values for self-checking, on very large data sets such as Holter recordings. Automatic templating and expert reannotation of a small number of templates lead to a reduction in the sample size requirements for definitive QT studies.

Synopsis of an epidemiologic study of a Kentucky county in the Coronary Valley

Kentucky is part of the Coronary Valley, which comprises ten states along the Ohio and Mississippi Rivers that rank among those with the highest incidence of heart disease in the United States. Kentucky consistently ranks near the highest in the nation, and within the state, the incidence is markedly higher in the eastern, Appalachian region. In a study of heart disease risk factors among residents of Clay County, which is located in this region, woe found, surprisingly, that the prevalence of elevated plasma cholesterol is slightly lower than in the United States overall. However, we noted a higher incidence of other traditional risk factors, including hypertension, cigarette smoking, obesity, and physical inactivity in this county, as well as a greater frequency of metabolic syndrome (MS) components. These findings may explain the high prevalence of cardiovascular (CV) disease in general and coronary heart disease (CHD) in particular, in parts of rural Appalachia even without the presence of significantly elevated cholesterol levels.

Electrocardiographic reference ranges derived from 79,743 ambulatory subjects

BACKGROUND

Reference ranges for electrocardiogram (ECG) intervals, heart rate, and QRS axis in general use by medical personnel and ECG readers are unrepresentative of true age- and sex-related values in large populations and are not based on modern electrocardiographic and ECG reading technology.

METHODS AND RESULTS

The results of ECG interpretation by cardiologists using digital technology for viewing and interpreting ECGs were compiled from single, baseline ECGs of 79,743 individuals included in pharmaceutical company-sponsored clinical trials. Women comprised 48% of the total population. Ages ranged from 3 months to 99 years, and the bulk of the population (56%) was aged 40 to 70 years. Striking differences in numerical ECG values based on age and sex were observed. A subgroup of 46,129 individuals with a very low probability of cardiovascular disease was identified. The following were the reference ranges for this subgroup, determined using the 2nd and 98th percentiles: heart rate, 48 to 98 beats/min; PR interval, 113 to 212 milliseconds; QRS interval, 69 to 109 milliseconds; frontal plane QRS axis, -40 degrees to 91 degrees ; QT interval, 325 to 452 milliseconds; QTc-Bazett, 361 to 457 milliseconds; and QTc-Fridericia, 359 to 445 milliseconds. There were marked age- and sex-related variations in the reference ranges of this subgroup, and they differ substantially from previously reported norms. Small differences were observed in ECG values obtained using our digital methods as compared with readings done using paper tracings and values computed by 2 commercial computer algorithms.

CONCLUSIONS

We observed large differences in electrocardiographic heart rate, interval, and axis reference ranges in this study compared with those reported previously and with reference ranges in general use. We also observed a large influence of age and sex upon normal values. Very large cohorts are required to fully assess age- and sex-related variation of reference ranges. Electrocardiographic reference ranges should be modernized.

Recommendations for the standardization and interpretation of the electrocardiogram: part I: the electrocardiogram and its technology a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society endorsed by the International Society for Computerized Electrocardiology

This statement examines the relation of the resting ECG to its technology. Its purpose is to foster understanding of how the modern ECG is derived and displayed and to establish standards that will improve the accuracy and usefulness of the ECG in practice. Derivation of representative waveforms and measurements based on global intervals are described. Special emphasis is placed on digital signal acquisition and computer-based signal processing, which provide automated measurements that lead to computer-generated diagnostic statements. Lead placement, recording methods, and waveform presentation are reviewed. Throughout the statement, recommendations for ECG standards are placed in context of the clinical implications of evolving ECG technology.

Recommendations for the Standardization and Interpretation of the Electrocardiogram

This statement examines the relation of the resting ECG to its technology. Its purpose is to foster understanding of how the modern ECG is derived and displayed and to establish standards that will improve the accuracy and usefulness of the ECG in practice. Derivation of representative waveforms and measurements based on global intervals are described. Special emphasis is placed on digital signal acquisition and computer-based signal processing, which provide automated measurements that lead to computer-generated diagnostic statements. Lead placement, recording methods, and waveform presentation are reviewed. Throughout the statement, recommendations for ECG standards are placed in context of the clinical implications of evolving ECG technology.

Recommendations for the Standardization and Interpretation of the Electrocardiogram

This statement provides a concise list of diagnostic terms for ECG interpretation that can be shared by students, teachers, and readers of electrocardiography. This effort was motivated by the existence of multiple automated diagnostic code sets containing imprecise and overlapping terms. An intended outcome of this statement list is greater uniformity of ECG diagnosis and a resultant improvement in patient care. The lexicon includes primary diagnostic statements, secondary diagnostic statements, modifiers, and statements for the comparison of ECGs. This diagnostic lexicon should be reviewed and updated periodically.

Recommendations for the Standardization and Interpretation of the Electrocardiogram

This statement provides a concise list of diagnostic terms for ECG interpretation that can be shared by students, teachers, and readers of electrocardiography. This effort was motivated by the existence of multiple automated diagnostic code sets containing imprecise and overlapping terms. An intended outcome of this statement list is greater uniformity of ECG diagnosis and a resultant improvement in patient care. The lexicon includes primary diagnostic statements, secondary diagnostic statements, modifiers, and statements for the comparison of ECGs. This diagnostic lexicon should be reviewed and updated periodically.

Recommendations for the standardization and interpretation of the electrocardiogram. Part II: Electrocardiography diagnostic statement list. A scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society

This statement provides a concise list of diagnostic terms for ECG interpretation that can be shared by students, teachers, and readers of electrocardiography. This effort was motivated by the existence of multiple automated diagnostic code sets containing imprecise and overlapping terms. An intended outcome of this statement list is greater uniformity of ECG diagnosis and a resultant improvement in patient care. The lexicon includes primary diagnostic statements, secondary diagnostic statements, modifiers, and statements for the comparison of ECGs. This diagnostic lexicon should be reviewed and updated periodically.