Calcium Channel Blockers

Question 1

What are the two sub-catagories of caclium channel blockers?

Answer 1

Dihydropine: Amlodipine and nifedipine
Non-dihydropine: Verapamil
DILATAZEM COMES UNDER BOTH

Question 2

What are the differences between dihdyropine and non-dihydropine CCBS?

Answer 2

Dihydropine: Vaculature selective

Non-dihydropine: Caradio selective

Question 3

How do calcium channel blockers work?

Answer 3

Block calcium channels therefore decreasing intracellular calcium levels
This causes:
- Vasodilation in arterial smooth muscle
- Reduction in contractility of the heart and therefore force (negatively inotropic)
- Reduction in conduction and therefore rate of the heart (negatively chonotropic) **particularly over AV node

Question 4

How do CCBs work on the AV node?

Answer 4

They suppress cardiac conduction, particularly across the atrioventricular (AV) node, slowing ventricular rate.

Question 5

What affect to CCBs have on oxygen demand of the heart?

Answer 5

Reduced cardiac rate, contractility and afterload reduce myocardial oxygen demand, preventing angina. - similar to beta blockers

Question 6

What are the main indications for using CCBs?

Answer 6

1. STABLE Angina: NOT unstable angina (beta blockers are the alternative)
2. SUPRAventricular Cardiac arrhythmias e.g. AF, A flutter, SVT - usually diltazem and verapamil
3. Hypertension - usually amlodipine and nifedipine

Question 7

What are the contraindications of using CCBs?

Answer 7

• AV nodal conduction delay (all)
• UNSTABLE ANGINA (nifedipine and amlod)
• Severe aortic stenosis ( can cause collapse) (nifedipine and amlodipine)

Question 8

Which CCBs and why don’t you use CCBs in unstable angina?

Answer 8

Amlodipine and nifedipine should be avoided in patients with unstable angina as vasodilatation causes a reflex increase in contractility and tachycardia, which increases myocardial oxygen demand.

Question 9

When should CCBs be used with caution?

Answer 9

• Poor left ventricular function (Verapamil and diltiazem) can worsen heart failure
• Hepatic and renal insufficiency

Question 10

What are the common interactions with CCBs?

Answer 10

• beta blockers: HF, bradycardia and a-systole
• Other hypotensives
• Cyclosporin and digoxin increase CCB concentration

Question 11

What are the common side effects of CCBs?

Answer 11

Flushing
Headache
Ankle Swelling
Palpitations
Constipation
Bradycardia, Heart block and Cardiac Failure

Question 12

How are CCBs eliminated?

Answer 12

First pass metabolism