Anti-Hypertensives: Calcium Channel Blockers

Question 1

Calcium Channel Blockers drugs?

Answer 1

• Dihydropyridine (more cardioselective):
  Nifedipine, Amlodipine
• Non-dihydropyridine (more systemic):
  Verapamil, Diltiazem

Question 2

Calcium Channel Blockers contraindicated in?

Answer 2

Contraindicated in heart failure

Question 3

Calcium Channel Blockers Mechanism of Action?

Answer 3

• Inhibition of L type Ca2+ channels=
• ↓ Ca2+ influx, ↓ contractility
• ↓ contraction in smooth muscles causing vasodilation
• Greatest sensitivity in cardiac muscles
• Some extent of negative chronotropic effects due to prolonged plateau phase in depolarization

Question 4

Why are other cells in the body with calcium channels not affected?

Answer 4

Neuronal cells unaffected as they use S type channels

skeletal muscle uses intracellular Ca2+ stores

Question 5

Calcium Channel Blockers Side Effects?

Answer 5

• Hypotension when overdosed
• Bradycardia, increased when taken with β blocker
• Verapamil causes constipation and also interacts with digoxin
• Flushing, peripheral oedema, dizziness, headache

Question 6

Which drugs do Calcium Channel Blockers interact with?

Answer 6

Any CCB with β blocker= bradycardia

Verapamil with Digoxin