Azimilide dihydrochloride

Azimilide dihydrochloride is an antiarrhythmic drug with Vaughn Williams class III properties, which blocks both fast (IKr) and slow (IKs) components of the delayed rectifier cardiac potassium channel. The drug slows the heart rate slightly and, like other class III antiarrhythmic drugs, prolongs ventricular repolarization and thus, the QT interval. Unlike sotalol, another class III antiarrhythmic drug, azimilide does not exhibit reverse-use dependence, that is, its binding characteristics and effectiveness are not related to the heart rate. Azimilide is 85% bioavailable, reaches peak blood concentrations in 6-8 h and has a long elimination half-life of 114 h. Clinical trials have utilized once-daily dosing. These trials have tested the use of the drug for patients with supraventricular and ventricular arrhythmias.

Emotion Recognition Based on ECG Signals for Service Robots in the Intelligent Space During Daily Life

This paper presents our approach for emotion recognition based on Electrocardiogram (ECG) signals. We propose to use the ECG’s inter-beat features together with within-beat features in our recognition system. In order to reduce the feature space, post hoc tests in the Analysis of Variance (ANOVA) were employed to select the set of eleven most significant features. We conducted experiments on twelve subjects using the International Affective Picture System (IAPS) database. RF-ECG sensors were attached to the subject’s skin to monitor the ECG signal via wireless connection. Results showed that our eleven feature approach outperforms the conventional three feature approach. For simultaneous classification of six emotional states: anger, fear, disgust, sadness, neutral, and joy, the Correct Classification Ratio (CCR) showed significant improvement from 37.23% to over 61.44%. Our system was able to monitor human emotion wirelessly without affecting the subject’s activities. Therefore it is suitable to be integrated with service robots to provide assistive and healthcare services.

In Vitro Preclinical Cardiac Assessment of Tolterodine and Terodiline: Multiple Factors Predict the Clinical Experience

Terodiline and tolterodine are drugs used to treat urinary incontinence. Terodiline was removed from the market in 1991 for proarrhythmia, whereas tolterodine has a generally benign clinical cardiac profile. To assess differences in the electrophysiologic actions of these drugs, we evaluated their effects on hERG current (HEK cells) and cardiac Purkinje fiber repolarization. The IC50 for hERG block (37 degrees C) by tolterodine was 9.6 nM and by terodiline was 375 nM, values near or below clinical concentrations. Tolterodine elicited concentration-dependent prolongation of the action potential duration (APD90). In contrast, terodiline depressed the action potential plateau and induced triangulation without affecting APD90. The triangulation ratios (normalized ratio of APD50 over APD90) for terodiline were 0.94 and 0.59 for 1.0 and 10 microM and for tolterodine, were 0.99 and 0.97 at 7 and 70 nM. In summary, tolterodine, a potent hERG blocker, has a benign clinical cardiac profile at therapeutic concentrations that may be due to its lack of triangulation, as well as extensive plasma protein binding. However, at supratherapeutic concentrations, preclinical data predict risk of QT prolongation. These data suggest that hERG block and triangulation are among multiple factors that must be considered in preclinical cardiac safety assessments.

A benefit–risk assessment of class III antiarrhythmic agents

The prevalence of arrhythmia in the population is increasing as more people survive for longer with cardiovascular disease. It was once thought that antiarrhythmic therapy could save life, however, it is now evident that antiarrhythmic therapy should be administrated with the purpose of symptomatic relief. Since many patients experience a decrease in physical performance as well as a diminished quality of life during arrhythmia there is still a need for antiarrhythmic drug therapy. The development of new antiarrhythmic agents has changed the focus from class I to class III agents since it became evident that with class I drug therapy the prevalence of mortality is considerably higher. This review focuses on the benefits and risks of known and newer class III antiarrhythmic agents. The benefits discussed include the ability to maintain sinus rhythm in persistent atrial fibrillation patients, and reducing the need for implantable cardioverter defibrillator shock/antitachycardia therapy, since no class III antiarrhythmic agents have proven survival benefit. The risks discussed mainly focus on pro-arrhythmia as torsade de pointes ventricular tachycardia.

Symptoms at the time of arrhythmia recurrence in patients receiving azimilide for control of atrial fibrillation or flutter: results from randomized trials

BACKGROUND

Azimilide is a new antiarrhythmic agent being developed for the management for atrial fibrillation and flutter (AF). Four randomized, placebo-controlled, double-blind trials have been performed that investigated the effect of azimilide on time to first recurrence of symptomatic AF. This paper examines the data collected during those studies regarding the symptoms reported by patients at the time of AF recurrence

METHODS

At the time that patients reported their first documented symptomatic recurrence of arrhythmia, they were systematically asked whether or not they were experiencing any of the following 6 symptoms: palpitation, fatigue, chest pain, shortness of breath, dizziness, or sweating. Patients were required to answer yes or no. A symptom score was created varying from 0 to 6, in increasing order of number of symptoms reported. This was compared for patients receiving either of 2 doses of azimilide or placebo. The relationship between the number of symptoms, heart rate at time of arrhythmia recurrence and treatment was analyzed.

RESULTS

In 2 separate studies, azimilide at a dose of 125 mg/day significantly reduced the number of symptoms at the time of arrhythmia recurrence compared to placebo. On the other hand, in 2 studies, the dose of 100 mg/day did not significantly reduce symptom burden. The individual symptoms significantly reduced by azimilide125 mg/day were fatigue, shortness of breath, chest pain and dizziness. Palpitations and sweating were not significantly reduced. Modeling of heart rate at the time of arrhythmia recurrence, symptoms and treatment indicated that a small reduction in heart rate with azimilide accounted for only a small part of the symptom reduction. There was another effect of azimilide: an average reduction of 0.38 symptoms (P <.01) that was independent of heart rate.

CONCLUSION

Azimilide (125 mg/day) reduces the number of symptoms reported at the time of AF recurrence.

Azimilide inhibits multiple cardiac potassium currents in human atrial myocytes

BACKGROUND

Studies in animal cell preparations suggest that azimilide may produce a more desirable rate-dependent profile of class III action as a result of its effects on both the slowly (I(Ks)) and rapidly (I(Kr)) activating components of potassium current (I(K)). However, relatively little is known about the effects of azimilide on K(+) currents in human atrial cells. The present study investigated the effect of azimilide on the inward rectifier potassium current (I(K1)), delayed rectifier potassium current (I(K)), ultrarapid delayed rectifier current (I(Kur)), and transient outward potassium current (I(to)) in isolated single human atrial myocytes.

METHODS

The tight-seal, whole-cell voltage clamp technique was used to investigate the acute effects of azimilide on K(+) currents in single human atrial myocytes. The cells were isolated enzymatically from atrial tissues that were obtained from patients undergoing open-heart surgeries, with the approval of the local Institutional Review Board.

RESULTS

The average cell capacitance of the human atrial myocytes was 77.5 +/- 2.8 pF (Mean +/- standard error of mean, total 28 cells from 17 patients). We found that 100 microM of azimilide in the extracellular solution significantly inhibited the inward rectifier potassium current (12.3 +/- 3.1 vs 6.7 +/- 2.0 pA/pF, n = 12, P < 0.05) at the testing potential of -100 mV. Superfusion with 100 microM of azimilide for 10 minutes inhibited I(K) by 51.7 +/- 5.1% (from 3.4 +/- 0.5 to 1.6 +/- 0.2 pA/pF, n = 9, P < 0.01) at the clamping membrane potential of +40 mV. Human atrial cell I(Kur) was inhibited with 100 microM of azimilide by 38.6 +/- 4.4% (from 3.9 +/- 0.5 to 2.3 +/- 0.2 pA/pF, n = 9, P < 0.01, test potential = 40 mV). We also found that the average peak current amplitude of I(to) in these cells was significantly inhibited with 100 microM of azimilide by 60.3 +/- 5.9% (from 10.3 +/- 1.5 to 3.6 +/- 0.3 pA/pF, n = 6, P < 0.01, test potential = 50 mV).

CONCLUSION

The present study provides direct evidence that azimilide inhibits multiple cellular transmembrane K(+) currents in freshly isolated human atrial myocytes. Inhibition of these K(+) currents by azimilide, especially of I(Ks) and I(Kur) is likely to be the electrophysiologic basis for the prolongation of the action potential duration in the human atria which mediates its known antifibrillatory effects in atrial fibrillation and flutter.