Calcium channel blockers

Question 1

Calcium in vascular smooth muscle VSM

Answer 1

Calcium regulates contraction. Blocking prevents vasoconstriction
Selectively to arteries peripheral and in heart

Question 2

CCB in the heart

Answer 2

Lowers inotropic effects in myocardium
Reduces rate in SA node
Decreases excitability in AV
Calcium channels coupled to beta 1 in the heart so CCBs and Beta 1 blockers have identical effects on heart (in all three aspects)

Question 3

3 chemical families of CCBs

Answer 3

dihydropyridines (nifedipine) (don’t effect heart at therapeutic doses, only arteries)
Phenylalylamine (only verapamil)
Phenylalkylamine (diltiazem and benzothiazepine)

Question 4

Verapamil (covera-HS) indications

Answer 4

Angina, essential HTN, dysrhythmias

Question 5

5 direct effects of verapamil

Answer 5

Blockade at peripheral arterioles reducing BP
Blockade at heart arterioles increases coronary perfusion
Blocked SA reduces rate
Blocked AV reduces nodal conduction
Blocked at myocardium reduces contractility
Lowered BP induces baroreceptor reflex and therefore increases norepi but those results are cancelled out

Question 6

Net effect of verapamil

Answer 6

Vasodilation and increased coronary perfusion as the blocked nodes/myocardium get more norepi

Question 7

Cardiac dysrhytmias verapamil

Answer 7

Afib/flutter, PSVT, MAT because it slows AV conduction

Question 8

Adverse effects verapamil

Answer 8

Constipation - increase fluid and fiber - its a result of blocked calcium channels in smooth muscles of intestines
Dizziness, facial flushing, headache, edema

Question 9

Contras to verapamil

Answer 9

1. Hypersensitivity
2. 2nd or 3rd degree heart block
3. Hypotension
4. Ventricular Tachycardia
5. WPW – with atrial fibrillation/flutter
6. Acute MI
7. Sick sinus syndrome

Question 10

Verapamil and dig

Answer 10

Combined effect on AV node

Also increases dig levels by 60%

Question 11

Tox of verapamil

Answer 11

Hypotension, bradycardia, av block, vtach/fib
Calcium will counter vasodilation and negative intotropic effects but not reverse AV block
Norepi for hypotension
Atropine for AV block and bradycardia or pacing or glucagon for increased cAMP

Question 12

Diltiazem is a

Answer 12

CCB

Question 13

Nifedipine

Answer 13

CCB, but only hits VSM. More likely to cause reflex tachycardia (immediate reflex, not long term)

Question 14

Amlodipine

Answer 14

Norvasc. CCB that only blocks VSM