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24 Cards in this Set
- Front
- Back
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define--> use dependent or state-dependent
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channels that are being used frequently , or in an inactivated state, are more susceptible to block
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what phase do drugs that effect Na or Ca channels have an effect on
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phase 4 by reducing the ratio of Na or Ca permeability to K permeability
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define--> class 1 action
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Na channel blockers
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define--> class 2 action
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reduce adrenergic activity(Beta blockers)
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define--> class 3 action
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drugs that prolong the action potential duration(K channel blockers)
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define--> class 4 action
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blockade of the Ca channel current
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where do most class 3 drugs work
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on the rapid component of the delayed rectifier K current(IKr)
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characteristics of class 1A drugs
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prolong the APD and sissociate with intermediate kinetics
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characteristics of class 1B drugs
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shorten the APD in some heart tissues and dissociate with rapid kinetics
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characteristics of drugs with class 1C action
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minimal effects on APD and dissociate with slow kinetics
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drugs in the 1A subgroup
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procainamide, quinidine, disopyramide
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MOA for procainamide
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blocks Na channels which slows the upstroke of the AP, slows conduction, prolongs the QRS
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what other action does procainamide have outside of class 1 action
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nonspecifically blocks K channels
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extracardiac effects of procainamide
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ganglion blocker(hypotension)
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toxicity of procainamide
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QT prolongation(Torsades) and with long term therapy an SLE like syndrome
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what metabolite of procainamide is implicated in torsades
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NAPA
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how procainamide is metabolized
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hepatic metabolism and excreted in the urine
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therapeutic uses of procainamide
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Atrial and ventricular arrythmias
(DOC after lidocaine or amiodarone) |
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MOA of quinidine
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blocks Na channels which slows the upstroke of the AP, slows conduction, prolongs the QRS
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toxicity of quinidine
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cinchonism
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MOA of disopyramide
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blocks Na channels which slows the upstroke of the AP, slows conduction, prolongs the QRS
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CI for disopyramide
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heart failure
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approved use for disopyramide
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Ventricular arrhythmias
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drugs in the class 1B subgroup
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Lidocaine and Mexiletine
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