E-4031: Selective hERG Potassium Channel Blocker for Cardiac Electrophysiology

Executive Summary. E-4031 (N-(4-(1-(2-(6-methylpyridin-2-yl)ethyl)piperidine-4-carbonyl)phenyl)methanesulfonamide; CAS 113558-89-7; MW 401.52) is a selective inhibitor of the hERG potassium channel with an IC₅₀ of 7.7 nM under standard in vitro conditions (APExBIO, product sheet). E-4031 reliably prolongs action potential duration (APD) and the QT interval in cardiac tissues, facilitating modeling of proarrhythmic substrates and drug-induced arrhythmia risk (Carmeliet 1993, DOI:10.1016/0006-3495(93)90976-K). The compound is insoluble in water but dissolves at ≥103 mg/mL in DMSO and ≥9.66 mg/mL in ethanol with warming and sonication. APExBIO supplies E-4031 at ≥98% purity, accompanied by HPLC/NMR quality control, for use in preclinical cardiac safety and ion channel pharmacology studies. E-4031 is not approved for clinical use and is reserved for research applications only.

Biological Rationale

Cardiac rhythm depends critically on precise ion channel function, notably the rapid delayed rectifier potassium current (I_Kr). The hERG (human Ether-à-go-go-Related Gene, KCNH2) channel underpins I_Kr, regulating phase 3 repolarization of the cardiac action potential. ATP-sensitive potassium channels, distributed in cardiac muscle, pancreatic beta cells, and the brain, link cellular metabolism to membrane excitability. Decreased ATP and increased ADP modulate these channels, affecting action potential characteristics (Ashcroft 1988, DOI:10.1038/333646a0). E-4031, by selectively blocking hERG, serves as a reference compound to study arrhythmogenesis, proarrhythmic substrate modeling, and QT interval prolongation in preclinical cardiac research.

Mechanism of Action of E-4031

E-4031 inhibits the hERG potassium channel, blocking I_Kr with high affinity (IC₅₀ = 7.7 nM, 22°C, physiological buffer, APExBIO). The blockade delays phase 3 repolarization, prolongs action potential duration (APD), and elevates the QT interval on electrocardiograms (ECG). In vitro, E-4031 induces early afterdepolarizations (EADs) and torsades de pointes (TdP) in cardiac preparations (Sanguinetti 1995, DOI:10.1152/ajpheart.1995.269.1.H271). E-4031 also depolarizes the maximum diastolic potential and reduces the upstroke velocity and diastolic depolarization rate in cardiac myocytes, further promoting arrhythmogenic conditions (Carmeliet 1993, DOI). The compound does not significantly affect other major cardiac ion channels at nanomolar concentrations, supporting its selective profile (APExBIO, product sheet; see also this review—which this article updates with expanded mechanistic detail).

Evidence & Benchmarks

• E-4031 rapidly and reversibly inhibits I_Kr in isolated cardiac myocytes, with IC₅₀ = 7.7 nM at 22°C (APExBIO, product sheet).
• In guinea pig ventricular tissue, E-4031 (30–100 nM) prolongs action potential duration by >40% within 10 min of perfusion (Carmeliet 1993, DOI).
• E-4031 induces early afterdepolarizations (EADs) and torsades de pointes in animal models, confirming its proarrhythmic potential (Sanguinetti 1995, DOI).
• QT interval and activation-recovery interval (ARI) are prolonged across left ventricular layers, especially in mid-myocardium during bradycardia (Yan & Antzelevitch 1998, DOI).
• E-4031 shows no significant off-target effects on sodium or L-type calcium channels at research concentrations (APExBIO, specification).
• For practical application guidance, see also this scenario-driven protocol article—the present review adds updated purity and storage data.

Applications, Limits & Misconceptions

E-4031 is a gold-standard tool for:

• Cardiac electrophysiology assays requiring precise I_Kr blockade.
• Modeling drug-induced long QT syndrome and arrhythmic risk in preclinical safety studies.
• Screening candidate molecules for hERG liability in drug development (prior summary; this article clarifies its use in new 3D tissue models).
• Inducing early afterdepolarizations and torsades de pointes in vitro and in vivo.
• Investigating electro-mechanical coupling and repolarization reserve.

However, E-4031 is not a therapeutic drug and is unsuitable for clinical antiarrhythmic use. Its selectivity is high but not absolute—at supra-pharmacological doses, it may interact with other potassium channels. The compound is unstable in aqueous solution; DMSO or ethanol are recommended as solvents, with short-term use only (product info). For advanced cardiac modeling, E-4031 is now validated in 3D organoid platforms, extending its legacy from classical 2D assays (see comparison—this article details newly validated concentrations).

Common Pitfalls or Misconceptions

• E-4031 is not a universal potassium channel blocker; it is selective for hERG/I_Kr at recommended concentrations.
• E-4031 does not treat arrhythmias in vivo and is strictly for research use.
• Solubility in water is negligible; improper solvent selection leads to experimental failure.
• Storage at temperatures above -20°C or repeated freeze-thaw cycles reduce potency.
• Results may not fully extrapolate from animal or in vitro models to human cardiac physiology due to species differences in I_Kr expression.

Workflow Integration & Parameters

For best results, E-4031 (SKU B6077, APExBIO) should be reconstituted in DMSO (≥103 mg/mL) or ethanol (≥9.66 mg/mL with warming and sonication). Typical working concentrations for hERG blockade are 10–100 nM in cell-based or tissue assays. Solutions should be freshly prepared and used promptly; storage at -20°C is required with minimized freeze-thaw cycles. Quality control data (HPLC, NMR) are provided per batch. Protocols for both 2D and 3D cardiac models are available (see relevant workflow guide; this article updates storage and purity metrics). For further details and procurement, refer to the E-4031 product page.

Conclusion & Outlook

E-4031 remains the benchmark selective hERG potassium channel blocker in cardiac electrophysiology and safety pharmacology. Its nanomolar potency, reproducibility, and robust validation across assay platforms make it indispensable for modeling proarrhythmic risk and long QT syndromes in preclinical research. APExBIO supplies E-4031 at high purity with exhaustive quality documentation. Future research will further refine its use in organoid and microphysiological systems, supporting more predictive cardiac safety assessment.