Calcium channel blockers

Question 1

Two main classes of calcium channel blockers and examples?

Answer 1

Dihydropyridines (Amlodipine, nifedipine, felodipine)
Non-Dihydropyridines (verapamil, diltiazem)

Question 2

Difference in mode of action for Dihydropyridines and non-Dihydropyridines?

Answer 2

Dihydropyridines - acts coronary and peripheral vasculature

Non-Dihydropyridines - more selective for coronary

Question 3

Indications for using calcium channel blocker?

Answer 3

HTN, angina (IHD)

Question 4

Mode of action of calcium channel blocker?

Answer 4

Blocks Ca2+ channels in myocardium, reduces intracellular Ca2+ concentration:

1) Reduced myocardial contractility
2) Supressed cardiac conduction, slowing ventricular rate
3) Relaxation and vasodilation in arterial SM, lowering arterial pressure

Reduce myocardial O2 demand

Question 5

Side effects of calcium channel blockers (amlodopine/nifedipine, verapamil)

Answer 5

vasodilation and compensatory tachycardia

A/N - ankle oedema, flushing, headache, palpitations
A - peripheral pitting oedema
V - constipation, less often bradycardia, heart block, cardiac failure

Question 6

Contraindications with calcium channel blockers?

Answer 6

Amlodipine and nifedipine should be avoided in unstable angina and severe aortic stenosis

Question 7

calcium channel blockers interactions and why?

Answer 7

Non-dihydropyridines should not be prescribed with Beta-blockers as they can cause bradycardia and AV block. Except under specialist supervision

Question 8

how to assess effectiveness of calcium channel blocker?

Answer 8

regular BP monitoring