Anti-arrythmatics drugs

Question 1

When are latent pacemakers more prone to acceleration of impulse?

Answer 1

1. Respose to B-adrenoreceptors stim
2. Hypokalemia
3. Fiber Stretch
4. Hypoxemia
5. Acidosis
6. Injury

Question 2

Class I Anti-arrhythmic Drugs

Answer 2

Sodium channel blockers:

1. Procainamide
2. Quinedine
3. Disopyramide
4. Lidocaine
5. Mexilitine
6. Flecanide
7. Propaferone

Question 3

Class II Anti-arrhythmic Drugs

Answer 3

Beta-Blockers:

1. Atenolol
2. Metoprolol

Question 4

Class III Anti-arrhythmic Drugs

Answer 4

Potassium Channel Blockers

1. Aminodarone
2. Sotolol*
3. Dofetilide
4. Ibutilide

Question 5

Class IV Anti-arrhythmic Drugs

Answer 5

CCBs:

1. Verapamil
2. Diltiazem

Question 6

MOA of Class I Anti-arrhythmic Drugs

Answer 6

1. Block Na+ channels which slows conduction in ectopic pacemakers (myocytes) - decreases slope of phase 0
2. Increases refractory period by increasing the membrane voltage needed for a new depolarization (lowers phase 4)

Question 7

MOA of Class Ia Anti-arrhythmic Drugs

Answer 7

Intermediate dissociation rate (T>1s)
*exception to rule: These PROLONG AP duration by also blocking K+ channels (@ High doses)

• decrease slope of phase 0 (Na+)
• also stretch phase 3 (K+)

Question 8

Class Ia Anti-arrhythmic Drugs

Answer 8

1. Procainamide
2. Quinidine
3. Disopyramide

Question 9

MOA of Class Ib Anti-arrhythmic Drugs

Answer 9

Rapid dissociation rate (T

Question 10

Class Ib Anti-arrhythmic Drugs

Answer 10

1. Lidocaine

2. Mexilitine

Question 11

MOA of Class Ic Anti-arrhythmic Drugs

Answer 11

Slow dissociation rate (T>10s)

- Pronounced slowing of Depolarization (decreased slope of phase 0)

Question 12

Prototype Class Ic Anti-arrhythmic Drug and its use?

Answer 12

Flecanide
- used in PTs w/ supraventricular arrhythmias w/o structural heart disease

-afib, aflutter, PSVT

Question 13

MOA of B-blockers (Class II) in regards to arrhythmias

Answer 13

Reduce the enhanced automaticity related to catecholamines and ischemia via slowing conduction

Question 14

When are beta-blockers used to tx arrhythmias?

Answer 14

Supraventricular arrhythmias

Question 15

MOA of Class III Anti-Arrhythmatics?

Answer 15

Block K+ channels which delays phase 2 and 3* repolarization, and thus:

• extends the AP duration
• increases duration of effective refractory period

Question 16

What limits the use of Class III Anti-Arrhythmatics?

Answer 16

The delayed repolarization can result in prolonging the QT interval which increases the risk of early afterdepolarization (EAD) and Torsade de Pointe

Question 17

MOA of Class IV Anti-Arrhythmatics?

Answer 17

Reduce SA node automaticity and AV node conduction

• little effect on fast conduction system (myocytes)

Question 18

Adverse effects and contraindications for CCBs as anti-arrhythmatics?

Answer 18

AE:

• SA and AV block
• Impaired myocardial contractility
• hypotension

Contraind: CHF, Sinus Bradycardia, and AV block (prolonged PR interval)

Question 19

MOA of Digoxin

Answer 19

Anti-arrhythmic effects mediated by increased vagal nerve activity which:
- reduces SA node automaticity, and AV conduction

• note: Completely diff MOA for it’s use in CHF (increasing Ca2+ availability)
• This may have an arrhythmogenic effect (adverse)

Question 20

Use of digoxin as an anti-arrhythmatic?

Answer 20

Controls ventricular rate in supraventricular arrhythmias

Question 21

Use and MOA of Adenosine

Answer 21

Used to terminate acute PSVT by blocking AV node via its adenosine receptor

*Blocks AV node -> asystole (~3 seconds) then comes back

Question 22

Adverse effects of Adenosine as an anti-arrhythmatic?

Answer 22

1. Chest tightness

2. Transient asystole (Flatline)

Question 23

Side effects of Class Ia Anti-arrhythmic Drugs

Answer 23

1. drug-induced lupus (procainamide)
2. Torsades de Pointes

• usually occur w/ long-term use.
• short-term IV use only (to limit side effects)

Question 24

Anti-arrhythmatic that causes urinary retention?

Answer 24

Disopyramide (Class Ia Anti-arrhythmatic)

Question 25

Exception of Lidocaine's MOA

Answer 25

* Not effective in the atria arrhythmias | - Ventricular arrhythmias only (highly effective)

Question 26

Contraindications for Flecainide?

Answer 26

Contraindicated in patients with structural heart disease! | - e.g. LV dysfunction and CHD

Question 27

Side effects of Amiodarone?

Answer 27

1. Pulmonary fibrosis 2. Photosensitivity Dermatitis (gray-blue skin) 3. Corneal microdeposits (visual halos) 4. Thyroid problems 5. Proximal muscle weakness and Hepatitis *CYP3A4

Question 28

What class anti-arrhythmatic is Sotalol?

Answer 28

K+ blocker (Class III) *ALSO is a non-selective Beta-blocker

Question 29

Side effects and contraindications of Sotalol?

Answer 29

Same as for beta-blockers - asthma/ COPD - QT prolongation - Advanced renal insuficiency - advanced CHF - 2nd or 3rd degree heart block - sinus bradycardia * Can cause Torsade de pointe

Question 30

Drugs that may induce Torsade de pointe

Answer 30

Class III Anti-Arrhythmatics 1. Aminodarone** 2. Sotolol* 3. Dofetilide 4. Ibutilide -Also Class Ia: Quinidine and Procaineamide

Question 31

Which drug is contraindicated in Wolff-Parkinson-White?

Answer 31

Digoxin DO NOT give to PT w/ WPW - because accessory pathway is atrial so digoxin can increase transmission of atrial impulses to the ventricles via this pathway - Ca2+ blockers and Lidocaine may also lead to v-fib

Question 32

Addition pharm effects of Amiodarone?

Answer 32

Also has B-blocking (Class II) and CCB activity (Class IV)

Question 33

What are the "Pure" K+ Channel blockers and what is unique about their Effect in tx of arrhythmias?

Answer 33

1. Ibutilide 2. Dofetilide *Only used to tx atrial arrhythmias ( a-fib and A-flutter)

Question 34

Orally effective analog for lidocaine? and what side effect limits its use?

Answer 34

Mexilitine GI distress (diarrhea) limits use