Calcium Channel Blockers

Question 1

How do Ions flow within Ion Channels?

Answer 1

Via a concentration gradient or electrochemical gradient

Question 2

Explain how the membrane potential works?

Answer 2

Negative inward potential across the membrane; maintained by active transport of K into the cell and Na out of the cell
-K: High inside and low outside
-Na: Low inside and high outside
-Ca: very low inside and high outside

Question 3

What is the main type of voltage-gated Ca channel affected?

Answer 3

L-type; Ca 1.2; Cardiac Smooth Muscle/ Ca trigger contraction

Question 4

What is the MOA of CCB?

Answer 4

Block of channels in vascular smooth muscle = Vasdilation
-Decrease BP and Relief of Angina
Block of channels in cardiac muscle & SA/AV node
-Antiarrhythmic

Question 5

How does Vascular Smooth Muscle Contract?

Answer 5

Extracellular Ca entering the cell Via Ca 1.2; causing the release of the Intracellular Ca within the SR to act on myosin + actin = Contraction.

Question 6

How does Cardiac Smooth Muscle Contract?

Answer 6

Ca will bind to troponin C; causing a displacement of tropomysin; binding myosin to actin = contraction

Question 7

What are the classes of the CCB?

Answer 7

Dyhyrdopyridines, Phenylalkylamines [Verapimil],
Benzothiazepines [Diltalizem]

Question 8

What is the common structure of the DHP?

Answer 8

They have the DHP ring on all of them

Question 9

What are the DHP CCB?

Answer 9

The “-pines”
-Amlodipine, Nifedipine, Isradipine, Felodipine, Nisoldipine, Nimodipine, Nicardipine

Question 10

What do DHP CCB work good in?

Answer 10

Raynauds Syndrome [decrease in flow of blood] & in Isolated Systolic BP [Stiff arteries in elderly]

Question 11

What is the frequency of the DHP CCBs?

Answer 11

They are all taken ONCE daily expect for Isradipine and Nicardipine; they are taken ONCE or BID

Question 12

What are the side effects of the DHP CCB?

Answer 12

Tachycardia, Headache, Dizziness, Edema, Flushing
*CONTRAINDICTION: Grapefruit Juice, CYP3A4

Question 13

What is the importance Clevidipine?

Answer 13

It is used IV when PO is not possible

Question 14

What tissues are the DHP CCB most potent on?

Answer 14

They work the best on the Smooth Muscle
-DO NOT work well on Cardiac Muscle

Question 15

How do the DHP CCB work?

Answer 15

The DHP with bind to the CLOSED Ca channel; not allowing Ca to enter into the smooth muscle cell = vasodilation & decrease in BP

Question 16

What are the Non-DHP CCB?

Answer 16

Verapamil [Phenylalkylamine], Diltiazem [Benzothiazepine]

Question 17

What does Verapamil do?

Answer 17

It will cause vasodilation [not as good as DHP]
-will also slow down the SA/AV node: causing a decrease in CO and HR = decreasing BP

Question 18

How does Verapamil work?

Answer 18

It has to bind to the OPEN channel; which will inhibit the Ca from entering the cell, causing vasodilation
*Frequency Block

Question 19

What does Diltiazem do?

Answer 19

It will cause vasodilation [not as good as DHP
-will also slow down the SA/AV node: causing a decrease in CO and HR = decreasing the BP

Question 20

Explain the summary of cardiovascular effects of the CCB?

Answer 20

DHP: will slightly increase HR, not effect AV and Myocardial Contraction [does not affect the Cardiac Muscle] and with greatly increase arteriole vasodilation
Verapamil: Moderately decrease HR, AV Contraction & Myocardial Contraction and moderately increase arteriole vasodilation.
Diltiazem: