Aprindine hydrochloride

Aprindine hydrochloride is a class I-b anti-arrhythmic agent and a hERG channel blocker with an IC50 of 0.23 μM. Aprindine hydrochloride has inhibitory effects on Na+/Ca2+ exchanger currents, which is partly responsible for their antiarrhythmic and cardioprotective effects. Aprindine hydrochloride is widely used for trial and ventricular tachyarrhythmias research research.

Aprindine (3 μM) inhibits the delayed rectifier K⁺ current (I_K) with little influence on the inward rectifier K⁺ current (I_K1) or the Ca²⁺ current^[2].
The muscarinic acetylcholine receptor-operated K⁺ current (I_K.ACh) was activated by the extracellular application of carbachol (1 μM) or by the intracellular loading of GTPγS. Aprindine inhibits the carbachol- and GTPγS-induced I_K.ACh with the IC₅₀ values of 0.4 μM and 2.5 μM, respectively^[2].

References:
[1]. M L De Bruin, et al . Anti-HERG activity and the risk of drug-induced arrhythmias and sudden death. Eur Heart J. 2005 Mar;26(6):590-7.
[2]. Y Ohmoto-Sekine, et al. Inhibitory effects of aprindine on the delayed rectifier K+ current and the muscarinic acetylcholine receptor-operated K+ current in guinea-pig atrial cells. Br J Pharmacol. 1999 Feb;126(3):751-61.