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Quinidine: |
Class Ia Antiarrhythmic |
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This
is the prototype class Ia drug, however, Quinidine is now being used less in
favor of other drugs which have less potential for severe side effects.
Quinidine decreases conduction velocity, automaticity, and prolongs the
myocardial action potential. Both
peripheral and myocardial a-receptors
are inhibited by Quinidine which can, of course, lead to decreased vascular tone
and hypotension. Muscarinic
receptors are also inhibited, leading to a vagolytic increase in sympathetic
tone that can
HR via the sinus node, and increase
AV node conduction causing a faster ventricular rate in A fib/flutter, and
greater risk of other arrthythmias. Quinidine
does however slow the "fast" retrograde accessory pathway in AV nodal
tachycardias, and slows the ventricular response to WPW syndrome.
Dose:
Complex... deferred!
Side
Effects: Lots!
Contraindicated:
in pts with IVCDs, dig toxicity, escape rhythms, myasthenia gravis, other stuff
I'm sure!
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