Calcium Channel Blockers

Question 1

Calcium channels

Answer 1

G-protein gated pores in membranes that regulate entry of calcium ions into cells

Question 2

Vascular Smooth Muscle (VSM) calcium channels

Answer 2

have G-protein receptors that regulate contraction

Calcium flows into cell and initiates contractile process

Receptors are Alpha-1 adrenergic receptors

CCBs act on peripheral arterioles and arteries and arterioles of heart
- NO significant effect on veins

Question 3

Heart Calcium Channels
What receptors are they coupled to

Answer 3

regulate myocardium, SA node, and AV node

coupled to Beta1 adrenergic receptors (Gprotein receptors)
- when activated Ca influx ENHANCED

Question 4

What Ca does at Myocardium, SA and AV node

Answer 4

Myocardium- calcium increases force of contraction

SA and AV node
channels open= node discharge increases
channels closed= node discharge decreases

Question 5

CCBs 2 Classifications

Answer 5

1) Dihydropyridines
- acts on SYSTEMIC arterioles (alpha 1 receptors)

2) Non dihydropyridines
- acts on arterioles and the heart (Beta 1 receptors

Question 6

dihydropyridines vs non-dihydropyridines vasodilation and heart fxn

Answer 6

Dihydropyridines
- more effect vasodilation
- less effect heart

Non-dihydropyridines
- less effect vasodilation
- more effect heart fxn

Question 7

Non Dihydropyridines drug name

Answer 7

Verapamil

Question 8

What does Non-dihydropyridines do

Answer 8

block calcium channels in blood vessels and heart

Question 9

indications of non-dihydropyridines

Answer 9

Angina pectoris
Essential Hypertension
Cardiac dysthymias

Question 10

Directeffects of Non Dihydropyridines

Answer 10

1) blockage in heart arteries/arterioles
= increased coronary perfusion

2) Blockage of SA node
= reduced HR

3) Blockage of AV node
= slows AV nodal conduction

4) Blockage of myocardium
= decreased force of contraction

Question 11

Indirect Effects of Non Dihydropyridines

Answer 11

Lowering blood pressure

Question 12

Pharmacokinetics of Non Dihydropyridines

Answer 12

PO- effects in 30 min, peak in 5 hrs
- extensive first-pass metabolism
- 20% reach systemic circulation

IV

Elimination: liver to bile

Question 13

Therapeutic Use of Non Dihydropyridines

Answer 13

angina pectoris, essential hypertension

cardiac dysrhythmias
-administer via IV - improves atrial flutter/fibrillation
= reduced tachycardia

Question 14

adverse effects of Non Dihydropyridines

Answer 14

Constipation
- calcium channels blocked in intestinal smooth muscle

cardiac effects
-bradycardia due to blockage of SA node

Dizziness, headache, edema

Question 15

Non Dihydropyridines drug and food interactions

Answer 15

Digoxin: supresses AV conduction

other Beta-adrenergic blockers

Grapefruit juice: inhibit liver metabolism of drugs
= reaise their level

Question 16

Toxicity of Non Dihydropyridines

Answer 16

overdose
- severe hypotension and cardiotoxicity (bradycardia, AV block)

Treatment: activated charcoal removes drug from GI tract

Question 17

Dihydropyridines drug name

Answer 17

Nifedipine

Question 18

Effects of Dihydropyridines

Answer 18

1) DIRECT - block alpha-1 calcium-chaneels in VSM
= vasodilation = reduced systemic BP

2) INDIRECT- reduce systemic BP
= more flow to heart
= increased HR

NET EFFECT: lowers BP
= increases flow to heart
= INCREASED HR rate and contractile force

Question 19

Pharmocokinetics of Dihydropyridines

Answer 19

PO
-extensive first pass (50% enters circulation)

Question 20

Therapeutic uses of Dihydropyridines

Answer 20

Angina pectoris:
prevent reflex tachycardia

Essential Hypertension

Question 21

Adverse effects of Dihydropyridines

Answer 21

peripheral edema

dizziness

headache

less constipation

TOXICITY = drug loses selectivity
= begins to affect heart