B / 5 : Drugs Influencing Cardiac Physiology

Question 1

What do class I anti-arrythmitic drugs do?

Answer 1

They are Na+ channel blockers

Question 2

What are the class I anti-arrythmitic drugs?

Answer 2

• Lidocaine (I/B)
• Propafenone (I/C)

Question 3

Lidocaine
- MOA
- Effect
- Indication
- Contraindication
- SE
- ROA

Answer 3

• Na+ channel blocker I/B
• Decreased Na+ influx raises the depolarization threshold : heart less likely to conduct AP that causes arrythmias
• For arrythmias, tachycardia, digitalis intoxication
• Not if bradyarrhythmias, HF
• CNS (tremors, seizures), Anaphylaxis
• IV injections

Question 4

Propafenone
- MOA
- Effect
- Indication
- Contraindication
- SE
- ROA

Answer 4

• Na+ channel blocker (I/C)
• Decreased excitability and negative inotropic effect (due to B blocker effect)
• For supraventricular arrhythmias, ventricular tachycardias
• Heart failure
• Pro-arrythmogenic effects, visual disturbances, dizziness
• Oral

Question 5

What are class II anti-arrhythmitic drugs?

Answer 5

They are beta blockers (esmolol)

Question 6

Esmolol
- MOA
- Effect
- Indication
- Extra
- ROA

Answer 6

• Beta 1 blocker
• Decreases cAMP and inhibits funny Na+ and Ca2+ currents : negative inotropic, chronotropic, dromotropic effects
• For SV arrhythmias, atrial fibrillation
• Does not pass BBB
• IV infusion

Question 7

What are class III anti-arrhythmic drugs?

Answer 7

K+ channel blockers

Question 8

What are the class III anti-arrhythmic drugs? (2)

Answer 8

• Amiodarone
• Sotalol

Question 9

Amiodarone
- MOA
- Effect
- Indication
- SE

Answer 9

• Strongest K+ channel blocker
• Prolonged AP and ERP (repolarization)
• For all arrhythmias
• Bradycardia, negative inotropy, hypotension, pulmonary fibrosis

Question 10

Sotalol
- MOA
- Effects
- Indication
- Contraindication
- SE
- ROA

Answer 10

• Non selective beta-antagonist and K+ channel blocker
• Decreases HR and AV conduction
• For supraventricular + ventricular tachycardia
• SSS, long QT syndrome, cardiogenic shock, asthma
• Bradycardia, Torsades de Pointes
• Oral and parenteral

Question 11

What are class IV anti-arrhythmic drugs?

Answer 11

Ca2+ channel blockers

Question 12

Verapamil
- MOA
- Effect
- Indication
- SE
- ROA

Answer 12

• Cardioselective Ca2+ channel blockers
• Slower conduction by SA and AV nodes
• Supraventricular arrhythmias
• Hypotension, constipation, nausea

Question 13

What are the class V anti-arrhythmic drugs (3)

Answer 13

• Adenosine
• Mg2+
• Digoxin

Question 14

Adenosine
- MOA
- Effect
- Indication
- SE
- ROA

Answer 14

• A1 and A2 receptor agonist
• A1 : Gi, causes increased K+ current and hyperpolarization. A2 : Gs, vasodilation
• Tachycardia, nodal arrhythmias
• Asystole, flushing, headache
• IV

Question 15

Mg2+
- MOA
- Indication

Answer 15

• Ca2+ channel blocker
• Torsades de Pointes, long QT syndrome, arrhythmias