The positive frequency-dependent electrophysiological effects of the IKur inhibitor XEN-D0103 are desirable for the treatment of atrial fibrillation.

Abstract

BACKGROUND:

Selective inhibitors of Kv1.5 channels are being developed for the treatment of atrial fibrillation (AF).

OBJECTIVES:

The purpose of this study was to investigate the effects of the highly selective Kv1.5 inhibitor XEN-D0103 on human atrial action potentials (APs) at high excitation rates and to assess safety.

METHODS:

Intracellular APs (stimulation rates 1-5 Hz) were measured in right atrial trabeculae from patients in sinus rhythm (SR), chronic AF (cAF; AF of >6 months duration), and paroxysmal AF (pAF). The safety and tolerability of XEN-D0103 were tested in a double-blind, randomized, placebo-controlled phase 1 study.

RESULTS:

Depending on its concentration, XEN-D0103 elevated the plateau potential. At 1 Hz, XEN-D0103 (3 µM) shortened action potential duration at 90% repolarization (APD90) and effective refractory period (ERP) in SR preparations, but prolonged these parameters in cAF preparations. In SR and pAF preparations, the shortening effects on APD90 and ERP turned into prolongation at high rates. In cAF trabeculae, XEN-D0103 prolonged APD90 and ERP at 2 and 3 Hz. At high rates, more SR and pAF preparations failed to capture excitation in the presence of the drug than in its absence. XEN-D0103 (10 µM) did not significantly affect human ventricular APs. Even with plasma concentrations reaching 7000 ng/mL, XEN-D0103 did not increase ∆∆QTcF (QT interval corrected by the Fridericia formula) in the analysis of electrocardiograms of healthy volunteers, and no subjects receiving an active treatment had a QT or QTcF interval >450 ms, or increase in QTcF from baseline >30 ms.

CONCLUSION:

APD prolongation and suppression of APs by XEN-D0103 at high stimulation rates in SR and pAF tissue, but not cAF, could be of therapeutic benefit for reducing AF burden. This concept needs to be confirmed in clinical trials.

• Authors: John Ford, James Milnes, Said El Haou, Erich Wettwer, Simone Loose, Klaus Matschke, Benoit Tyl, Patrick Round, Ursula Ravens
• Journal: Heart rhythm (Heart Rhythm) Vol. 13 Issue 2 Pg. 555-64 (Feb 2016) ISSN: 1556-3871 [Electronic] United States
• PMID: 26455450 (Publication Type: Clinical Trial, Phase I, Journal Article, Randomized Controlled Trial, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Chemical References

• Anti-Arrhythmia Agents
• Delayed Rectifier Potassium Channels

Topics

• Action Potentials (drug effects)
• Adult
• Anti-Arrhythmia Agents (administration & dosage, adverse effects, pharmacokinetics)
• Atrial Fibrillation (diagnosis, drug therapy, physiopathology)
• Delayed Rectifier Potassium Channels (antagonists & inhibitors)
• Electrocardiography (methods)
• Electrophysiologic Techniques, Cardiac (methods)
• Healthy Volunteers
• Heart Atria (drug effects, physiopathology)
• Humans
• Male
• Refractory Period, Electrophysiological (drug effects)
• Treatment Outcome