class 1 antiarrhythmics

[Turtlez]

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Are class 1 antiarrhythmics use dependent or state dependent? Please explain the difference as well please!

 

[J ROD]

Class I drugs bind more rapidly to open or inactivated sodium channels than to channels that are fully repolarized following recovery from the previous depolarization cycle. Therefore, these drugs show a greater degree of blockade in tissues that are frequently depolarizing (for example, during tachycardia, when the sodium channels open often). This property is called use-dependence (or state-dependence) and it enables these drugs to block cells that are discharging at an abnormally high frequency, without interfering with the normal, low-frequency beating of the heart.

 

[Turtlez]

thankss!