Calcium Channel Blockers

Question 1

How are CCB specific to cardiac and vasculature?

Answer 1

Only binds to L-type Ca+2 channels which are located in vasculature and cardiac muscle.
N-type and P-type are not bound by CCB

Question 2

What is Use-dependent binding and what drugs use this mechanism?

Answer 2

Use-Dependent is when the channels are used more frequently, which allows the binding site to be exposed more frequently. Diltiazam and Verapamil

Question 3

What is Voltage-Dependent binding and what drugs use this mechanism?

Answer 3

Voltage-Dependent is when the drug binds based upon the membrane potential, whereas Nifedipine and Amlodipine bind to smooth muscle because the depolarization is lower (less negative), compared to cardiac muscle which is more polarized.

Question 4

How do Calcium channel blockers effect one another’s binding?

Answer 4

Allostericly, binding of one can increase or decrease binding of another.

Question 5

What is a unique adverse effect of Dihydropyridines, more specifically Nifedipine?

Answer 5

Reflexive Tachycardia and Contractility, due to blood pressure lowering too quickly.

Question 6

What CCB has the lowest bioavailablity?

Answer 6

Verapamil. Significant first pass effect.

Question 7

What drug is best at reducing conduction?

Answer 7

Verapamil

Question 8

What drug is typically used for Angina and rate control?

Answer 8

Diltiazam. Reduces AV firing rate and contractility with vasodilation properties of coronary arteries.

Question 9

What are the effects of Diltiazam and Verapamil?

Answer 9

Decrease SA node firing, reduce conduction of signal, thus causing reduced HR and Contractility. Also has effects on cardiac and arterial vessels dilating them.

Question 10

What makes Amlodipine different?

Answer 10

Amlodipine has a very long half life 30-50 hours and only effects the vasculature without direct heart effects.

Question 11

What are contraindications to Diltiazam and Verapamil?

Answer 11

CHF, Bradycardia, AV Conduction defects, and to a lesser extent hypotension.

Question 12

How can Diltiazam and Verapamil worsen CHF?

Answer 12

Their effects at lowering heart rate will decrease contractility, which a CHF patient’s heart is already functioning weakly that can cause worsening CHF symptoms. Verapamil > Diltiazam

Question 13

What are dihydropyridines primarily used for?

Answer 13

Hypertension treatment. Vasodilation effects on arterial vessels and reduces afterload. No effect on preload.

Question 14

What drug can cause constipation as a side effect?

Answer 14

Verapamil

Question 15

What drugs would be contraindicated with the patient had an LBBB and HTN?

Answer 15

Verapamil>Diltiazam. Would use Nifedipine or Amlodipine

Question 16

What drug class is Diltiazam a prototype of?

Answer 16

Benzothiazepines

Question 17

What drug class is Verapamil?

Answer 17

Phenylalkylamines

Question 18

What are the most common adverse effects of dihydropyridines?

Answer 18

Hypotension, Headache, Extremity Edema.

Question 19

Which drug Diltiazam or Verapamil are better tolerated?

Answer 19

Diltiazam. Verapamil have more side effects and have greater inotropic effects on the heart, thus being more susceptible to disease states like CHF and Heart Blocks.

Question 20

What are the three classes of calcium channel blockers?

Answer 20

Phenylalkylamine, Benzothiazepine, Dihydropyridines