Calcium Channel Blockers

Question 1

Give 3 examples of non-rate limiting CCBs?

Answer 1

• Amlodipine
• Felodipine
• Nifedipine

(they all end in -dipine)

Question 2

What are non-rate limiting CCBs known as?

Answer 2

Dihydropyridine CCBs

Question 3

Give 2 examples of rate-limiting CCBs?

Answer 3

• Verapamil

- Diltiazem

Question 4

What is important to note when prescribing diltiazem?

Answer 4

Should be prescribed by brand

Question 5

What is the mechanism of action of CCBs?

Answer 5

They inhibit the influx of calcium ions into vascular smooth muscle, therefore decreasing intracellular calcium, which reduces contractility, conductivity, and oxygen demand of the heart

Question 6

What are the routes of delivery of CCBs?

Answer 6

• PO

- IV

Question 7

What CCBs can be given IV?

Answer 7

• Verapamil

- Nicardipine

Question 8

Why are some CCBs available in a MR preparation?

Answer 8

As some have short half lives

Question 9

What are the indications for non-rate limiting CCBs?

Answer 9

• Prophylaxis in stable angina

- Hypertension

Question 10

When are CCBs first line in hypertension?

Answer 10

In those who are >55 or Afro-Caribbean

Question 11

Why are CCBs first line in Afro-Caribbean?

Answer 11

As low-renin hypertension for which CCBs are effective is common in this ethnic group

Question 12

What are the indications for rate-limiting CCBs?

Answer 12

• SVT
• Prophylaxis and treatment of angina
• Hypertension

Question 13

What can diltiazem cream be used for?

Answer 13

Haemorrhoids

Question 14

What are the cautions/contraindications for CCBs?

Answer 14

• Unstable angina
• Severe aortic stenosis
• Recent MI (within 1 month)

Question 15

What might CCBs interact with?

Answer 15

• Other anti-hypertensives
• Digoxin
• Theophylline
• Anti-epileptics

Question 16

What might happen if CCBs are given with digoxin?

Answer 16

Increased plasma digoxin concentration

Question 17

What might happen if CCBs are given with theophylline?

Answer 17

Increased plasma theophylline concentration

Question 18

What might happen if CCBs are given with anti-epileptic drugs?

Answer 18

Reduced effect of dihydropyridine CCBs

Question 19

What are the common side effects of CCBs?

Answer 19

• Headache
• Flushing
• Abdominal pain
• Hypotension
• Tachycardia
• Fatigue
• Peripheral oedema
• Cold peripheries

Question 20

What are the less common side effects of CCBs?

Answer 20

• Bradycardia, heart block and heart failure in patients with poor LV function
• Impotence

Question 21

What CCB causes impotence?

Answer 21

Felodipine

Question 22

What might happen to the side effects of flushing, hypotension, dizziness, and ankle swelling with CCBs?

Answer 22

May settle down after couple of weeks then resolve

Question 23

What patient counselling is required with CCBs?

Answer 23

• Lifestyle measures
• Food interactions
• Compliance in angina

Question 24

What should be discussed regarding lifestyle measures with CCBS?

Answer 24

Discuss reduction of other cardiovascular risk factors

Question 25

What should be discussed regarding food interactions with CCBs?

Answer 25

Do not consume grapefruit or its juice as this may interact

Question 26

Why should people not consume grapefruit with CCBs?

Answer 26

Grapefruit inhibits the CYP3A4 system, which increases the bioavailability of the calcium channel blocker and potentiates its anti-hypertensive effect

Question 27

What should be discussed regarding compliance with CCBs in angina?

Answer 27

If you have angina and stop taking CCB, may worsen