Sodium & Beta Blockers Flashcards Preview

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Flashcards in Sodium & Beta Blockers Deck (20):
1

General effect of sodium channel blockers

Alters AP duration and kinetics of Na channel

1

General effect of K+ channel blockade

Prolonged effective refractory period

2

General effect of beta blockers

Blockade of SNS effects in heart

3

General effect of Ca channel blockers

Slows conduction in cells with calcium-dependent depolarization

4

What do class I drugs bind? What is the result?

Bind to fast sodium channels --> slow the usually rapid depolarization (phase 0) in fast response cardiac action potentials --> decreased conduction velocity in non-nodal tissue

5

What is the effect of sodium channel blockers on nodal cells?

No direct effect (they depend on Ca for depolarization)

6

What accounts for the effects on ERP with class I drugs?

Not the sodium blockade but rather the non-specific secondary activity of them on efflux of K+ (phase 3)

7

What are the class I drug subdivisions? How does each subclass differ?

IA: (Quinidine) moderate sodium channel blockade, increase ERP
IB: (Lidocaine) weak sodium channel blockade, decreased ERP
IC: (Flecainide) strong sodium channel blockade, no ERP effect

8

Rank the class I subclasses from greatest to least sodium blockade

IC > IA > IB

9

Rank the class I subclasses: ____ increases ERP, ____ does not affect ERP, ___ decreases ERP

IA
IC
IB

11

Examples of subclass IA

Quinidine, procainamide, disopyramide

12

Examples of subclass IB

Lidocaine, Mexilitine, Tocainide

12

What are state-dependent drugs?

Only bind readily to activated or inactivated channels, not resting

13

Examples of subclass IC

Flecainide, Propafenone, Moricizine

14

When are state-dependent drugs helpful in CV situations

Fast tachycardia (many activations and inactivations) or significant loss of RMP (more channels inactivated instead of resting)

15

Therapeutic uses of class IA drugs

afib, flutter, SVT, VT

16

Therapeutic uses of class IB drugs

VT

17

Therapeutic uses of class IC drugs

Life threatening SVT and VT

18

What beta blocker should be avoided in asthmatics? Which beta blocker would be better/why?

Propranolol, can --> bronchospasm. Acebutolol better for asthmatics because it's B1 specific.

19

Sotalol specificity

Non-selective Beta blocker