Study note

Class I anti-arrhythmic drugs: actions and cautions

THE CONTEXT

Class I anti-arrhythmic drugs affect excitability and conduction in atrial or ventricular muscle by blocking sodium channels.

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Class I drugs principally suppress excitability and slow conduction in atrial or ventricular muscle.

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They block sodium channels, of which several types are present in cardiac tissue.

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Class I drugs should generally be avoided in heart failure because they depress myocardial function.

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Class Ia and Ic drugs are often pro-arrhythmic.

NEETx

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