Block of HERG Potassium Channels by the Antihistamine Astemizole and its Metabolites Desmethylastemizole and Norastemizole

@article{Zhou1999BlockOH,
  title={Block of HERG Potassium Channels by the Antihistamine Astemizole and its Metabolites Desmethylastemizole and Norastemizole},
  author={Z Zhou and Vicken R. Vorperian and Qiuming Gong and S Zhang and Craig T. January},
  journal={Journal of Cardiovascular Electrophysiology},
  year={1999},
  volume={10}
}
Electrophysiologic Effects of Astemizole Metabolites. Introduction: The selective H1‐receptor antagonist astemizole (Hismanal) causes acquired long QT syndrome. Astemizole blocks the rapidly activating delayed rectifier K+ current IKr and the human ether‐a go‐go‐related gene (HKRG) K+ channels that underlie it. Astemizole also is rapidly metabolized. The principal metabolite is desmethylastemizole, which retains H1‐receptor antagonist properties, has a long elimination time of 9 to 13 days, and… 
Interactions of the antimalarial drug mefloquine with the human cardiac potassium channels KvLQT1/minK and HERG.
TLDR
Inhibition by mefloquine of KvLQT1/minK in the human heart may in part explain the synergistic prolongation of QT interval observed when this drug is coadministered with the HERG antagonist halofantrine.
Interactions of the 5-hydroxytryptamine 3 antagonist class of antiemetic drugs with human cardiac ion channels.
TLDR
The antiemetic agents tested in this study block human cardiac Na(+) channels probably by interacting with the inactivated state, which may lead to clinically relevant Na(+ channel blockade, especially when high heart rates or depolarized/ischemic tissue is present.
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TLDR
Using inside- and outside-out patch recordings, it is found that a permanently charged, quaternary derivative of imipramine (N-methyl-imipramines) only blocks channels from the intracellular side of the membrane.
Cardiac hERG K+ Channel as Safety and Pharmacological Target.
TLDR
A reduction of the hERG/IKr current has been recognized as a predominant mechanism responsible for the drug-induced delayed repolarization known as acquired long QT syndromes (LQTS), which is linked to an increased risk for "torsades de pointes" ventricular arrhythmias and sudden cardiac death.
Blockade of the Human Ether A-Go-Go–Related Gene (hERG) Potassium Channel by Fentanyl
TLDR
Although mechanisms of fentanyl-related sudden death need further investigation, blockade of hERG channels may contribute to the death of individuals with high-concentration overdose or compromised cardiac repolarization.
Flunarizine is a Highly Potent Inhibitor of Cardiac hERG Potassium Current
TLDR
The effects of flunarizine on potassium currents through cardiac channels encoded by the human ether-a-go-go related gene (hERG) stably expressed in CHO cells are examined with standard whole-cell voltage-clamp techniques.
Effect of trazodone on hERG channel current and QT-interval.
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References

SHOWING 1-10 OF 44 REFERENCES
Antiallergic effects of major metabolites of astemizole in rats and guinea pigs.
TLDR
In the studies of histamine release from rat peritoneal mast cells induced by compound 48/80 or from lung fragments in actively sensitized guinea pigs, desmethylastemizole, 6-hydroxydesmethylast emizole and norastemIZole were much less potent than was astemizole.
Molecular basis for the lack of HERG K+ channel block-related cardiotoxicity by the H1 receptor blocker cetirizine compared with other second-generation antihistamines.
TLDR
Cetirizine in particular, which possesses more polar and smaller substituent groups attached to the tertiary amine compared with other antihistamines, lacks HERG-blocking properties, possibly explaining the absence of torsade de pointes ventricular arrhythmias associated with its therapeutical use.
Effects of nonsedating antihistamine, astemizole, on the in situ canine heart assessed by cardiohemodynamic and monophasic action potential monitoring.
TLDR
Drugs or interventions inducing positive chronotropic, inotropic, and dromotropic effects can become good candidates for the treatment of astemizole intoxication, which may attenuate the cardiac effects of a stemizole including the lengthening of repolarization.
Cardiac electrophysiological actions of the histamine H1-receptor antagonists astemizole and terfenadine compared with chlorpheniramine and pyrilamine.
TLDR
Block of repolarizing K+ currents, particularly IK1, by astemizole and terfenadine produces reverse rate-dependent prolongation of action potential duration and development of early afterdepolarizations, delays ventricular repolarization, and may underlie the development of torsade de pointes ventricular arrhythmias observed with the use and abuse of these agents.
Blockage of the HERG human cardiac K+ channel by the gastrointestinal prokinetic agent cisapride.
TLDR
Cisapride is a potent blocker of HERG channels expressed in HEK293 cells, which may account for the clinical occurrence of Q-T prolongation and ventricular arrhythmias observed with cisapride.
HERG, a primary human ventricular target of the nonsedating antihistamine terfenadine.
TLDR
It is proposed that the blocking of HERG by terfenadine explains the acquired long QT syndrome, and HERG is likely to be the primary target for the known cardiotoxic effects of other, related antihistamines.
Mechanism of block of a human cardiac potassium channel by terfenadine racemate and enantiomers
TLDR
It is suggested that terfenadine blocks the hKvl.5 channel after it opens by entering into the internal mouth of the channel and is about 6 times more potent than quinidine.
Suppression of mammalian K+ channel family by ebastine.
TLDR
It is concluded that ebastine blocks various cardiac K+ channels with different potencies, as well as on HERG-induced rapidly delayed rectifier K+ current in Xenopus laevis oocytes and in guinea pig ventricular myocytes.
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