Calcium-Channel Blockers

Question 1

What are the 2 common classifications of Ca++ channel blockers?

Answer 1

Dihydropyridines (DHPs)

Non-dihydropyridines (Non-DHPs)

Question 2

What are the names for some common DHPs?

Answer 2

Amlodipine (Norvasc)

Nifedipine (Procardia XL)

Question 3

What are the names for some common non-dihydropyridines?

Answer 3

Diltiazem (Cardizem CD/Cardizem LA)

Verapamil (Covera HA; Veretan PM)

Question 4

MOA - general

Answer 4

Decrease the amount of Ca++ entering the cell - increase the time the cells are relaxed
Ca++ used to initiate muscle contraction by attaching to cytosol of cell - released from SR and diffuses to activate actin - Ca++ attaches to troponin to move tropomyosin out of the way to initiate sliding of myofibrils so that cross-bridging (and then muscle contractions) can take place

Question 5

To what does Ca++ attach in the cytosol of the muscle cell after it diffuses out of the SR?

Answer 5

Troponin

Question 6

On what does Ca++ act after it enters the cytosol of the muscle cell after diffusing out of the SR?

Answer 6

Tropomyosin AFTER it attaches to troponin - tropomyosin is moved off of the binding site on actin to the myosin heads can attach and the cross bridges can form so that sliding of the myofibrils can occur ==> a Ca++ channel blocker will BLOCK this bc it decreases the amount of Ca++ entering the cytosol, so it keeps the muscle in a more relaxed state for a longer period of time

Question 7

MOA - DHPs

Answer 7

Inhibit influx of Ca++ in muscle cells –> peripheral arteriolar dilation

Question 8

MOA - Non-DHPs

Answer 8

Inhibit influx of Ca++ in muscle cells –> peripheral arteriolar dilation
Reduce myocardial O2 –> decreases CO

Question 9

Do DHPs and Non-DHPs both inhibit the influx of Ca++ in the muscle cells, dilating the arterioles in the periphery?

Answer 9

Yes

Question 10

What is the difference in the MOA between DHPs and Non-DHPs?

Answer 10

Non-DHPs also reduce myocardial O2, decreasing the CO

Question 11

Effect on BP

Answer 11

Decreasing BP and decreasing SVR ==> decrease in BP
BP = CO x SVR ==> meds prevent aa. and arterioles from constricting (as during a contraction), so they are more relaxed and the LV does not have to work as hard (decreased CO)

Question 12

What is the suffix associated with DHPs?

Answer 12

-dipine

Question 13

Which class of CCBs are the most month muscle selective?

Answer 13

DHPs (Amlodipine; Nifedipine)

Question 14

What are indications for use of DHPs?

Answer 14

HTN

Angina

Question 15

What are some common adverse reactions of DHPs (Amlodipine; Nifedipine)?

Answer 15

Muscle weakness
GERD
Constipation 
Flushing
Pedal edema

Question 16

What are the two common actions of Non-DHPs (Diltiazem; Veramapil)?

Answer 16

Cardiac depressant

Vasodilation

Question 17

What are indications for use of Non-DHPs (Diltiazem; Veramapil)?

Answer 17

HTN
Angina
Atrial arrhythmias

Question 18

What are some common adverse reactions of Non-DHPs (Diltiazem; Veramapil)?

Answer 18

Excessive bradycardia
Muscle weakness
GERD
Constipation
Contraindicated in heart failure

Question 19

What are the different adverse reactions between DHPs and Non-DHPs?

Answer 19

DHPs: pedal edema

Non-DHPs: excessive bradycardia

Question 20

Which class of CCBs is contraindicated in CHF?

Answer 20

Non-DHPs