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10 Cards in this Set

  • Front
  • Back
Class 1A
-Effect on primarily which ion
-Effect on phase of AP
*Na+ channel blocker

*Na+ inward

*Phase 0, Lengthens AP
Class 1B
*Na+ channel blocker

*Na+ inward

*Phase 0, little change in AP length
Class 1C
Na+ channel blocker

Na+ inward

Phase 0, slows conduction
Class 1 with regards to dissociation rate
1A= intermediate
1B= Fast (least potent)
1C= slow (most potent)
Class II
Beta-antagonists (block Beta-receptor on Ca++ channels causing decreased Ca++ influx and increased time required for repolarization in phase II.

Na+ inward, K+ outward

Phases I,II,IV, slows conduction
Class III
K+ channel blocker

K+ outward

Phase III, lengthens AP
Class IV
Ca++ channel blockers

Ca++ inward

Phase II, slows conduction
SAR of Na+ channel blockers (Class 1A)
1. Functional group that mimics Na+ (able to be ionized)

2.Hydrophobic bulk to physically block the Na+ channel
If a class 1A agent is acetylated, what effect does it have on the drug?
NAPA (N-acetyl procainamide): 25% activity of parent
SAR of Na+ channel blockers (Class 1B)
1. Reverse amide

2. Ortho bulk

3. Functional gp that mimics Na+ (able to be ionized=amine,+, Nitrogen,-,)