Calcium-Channel Blocker

Front 1

In general, how do calcium channel blockers work?

Back 1

They interfere with inward calcium ion movement across myocardial and vascular smooth muscle.

Front 2

What are phenylalkylamines selective for?

Back 2

AV node

Front 3

What are dihydropyridines selective for?

Back 3

Arteriolar beds

Front 4

What are benzothiazepines selective for?

Back 4

AV node

Front 5

In general, what is the mechanism of action of calcium channel blockers?

Back 5

1. Bind to the alpha-1 subunit of the L-type slow channel (phase II)
2. Channel becomes into an inactivated state
3. Diminish entry of calcium into the cell

Front 6

What category of calcium channel blocker does verapamil belong to?

Back 6

Phenylalkylamines

Front 7

What are the pharmacologic effects of calcium channel blockers?

Back 7

1. Decreased myocardial contractility
2. Decreased heart rate
3. Decreased activity of the SA node
4. Decreased rate of conduction through the AV node
5. Decreased SBP
6. Vascular smooth muscle contraction
7. Increased coronary blood flow
8. Negative inotropic effect
a) verapamil and cardizem
9. Treatment for chronic stable angina

Front 8

What are the side effects of Verapamil?

Back 8

1. Major depressant effect on AV node
2. Negative chronotropic effect on SA node
3. Negative inotropic effect on cardiac muscle
4. Moderate vasodilation effect on coronary and systemic arteries

Front 9

What are the clinical uses of verapamil?

Back 9

1. Supraventricular tachydysrhythmias
2. Vasospastic angina
3. Symptomatic hypertrophic cardiomyopathy with or without left ventricular outflow obstruction
4. Maternal and fetal tachydysrhythmias
5. Premature labor

Front 10

What is the active metabolite of verapamil?

Back 10

Norverapamil

Front 11

How do dihydropyrimidines work?

Back 11

1. Prevents calcium entry by extracellular allosteric modulation of calcium ion channels.
2. Primary affinity is peripheral arterioles.
3. Reflex tachycardia may be observed.

Front 12

What calcium channel blocker has the strongest effect on coronary arteries?

Back 12

Nifedipine

Front 13

How does nifedipine work?

Back 13

1. Coronary and peripheral arterial dilator
a) moreso than verapamil
2. No depressant effect of SA and AV node
3. Direct negative inotropic, chronotropic, and dromotropic effect
4. Cardiac depressant effect on left ventricular dysfunction, beta blocker tx, or aortic stenosis.

Front 14

List clinical uses of nifedipine.

Back 14

Tx for angina due to coronary artery vasospasm.

Front 15

List pharmacokinetics of nifedipine.

Back 15

1. Given orally or sublingually
2. Protein binding of 90%
3. Hepatic metabolism

Front 16

List side effects of nifedipine.

Back 16

1. Flushing
2. Vertigo
3. Headache
4. Renal dysfunction may be induced

Front 17

What is the mechanism of action of benzothiazepines?

Back 17

It is not well understood.

Front 18

What category of calcium channel blockers does nifedipine belong to?

Back 18

Dihydropyrimidines

Front 19

What category of calcium channel blockers does diltiazepam belong to?

Back 19

Benzothiazepines

Front 20

How does diltiazepam work?

Back 20

1. Blocks calcium channels at the AV node.
2. Minimal cariodpressant effect.

Front 21

List clinical uses of diltiazepam.

Back 21

1. Tx for supraventricular tachydysrhythmias.
2. Tx for chronic control of essential HTN

Front 22

What is the angina dose of diltiazepam?

Back 22

0.25-0.35 mg/kg IV over 2 minutes then 10 mg/hr infusion for 24 hours.

Decrease dosage in liver disease.

Front 23

How do digitalis and beta-blockers interact with verapamil and diltiazem?

Back 23

Pts with preexisiting cardiac conduction abnormalities may experience greater AV block.

Front 24

How do volatile anesthetics interact with calcium channel blockers?

Back 24

Exaggerated myocardial depression and peripheral vasodilation.

Front 25

What might happen to pts with hypovolemic pts who are administered calcium channel blockers?

Back 25

Exaggerated systemic hypotension.

Front 26

How can you revers calcium channel blocker toxicity?

Back 26

1. Calcium chloride
2. Dopamine

Front 27

What are some pharmacodynamic effects of calcium channel blockers?

Back 27

1. Vasodilation
2. Myocardial depression
3. Negative inotropic effect
4. Depressant effect on SA node function
5. Peripheral vasodilation

Front 28

What considerations should you keep in mind on pts undergoing anesthesia who are on calcium channel blockers?

Back 28

1. Volatile anesthetics have blocking effect on calcium channels.
2. Administer with caution to pts with impaired left ventricular function or hypovolemia.

Front 29

How do neuromuscular blockers interact with calcium channel blockers?

Back 29

1. Neuromuscular blockers are potentiated
2. Edrophonium is effective in antagonizing potentiation

Front 30

How do local anesthetics interact with calcium channel blockers.

Back 30

May increase local anesthetic toxicity.

Front 31

How do potassium containing solutions interact with calcium channel blockers?

Back 31

Hyperkalemia may occur after small endogenous potassium infusion because of blocking of the inward movement of potassium ions.

Front 32

How does dantrolene interact with calcium channel blockers?

Back 32

1. Hyperkalemia
2. Cardiovascular collapse

Front 33

Do calcium channel blockers interfere with calcium medicated platelet functions?

Back 33

Yes

Front 34

How does digoxin interact with calcium channel blockers?

Back 34

Increased plasma concentration of digoxin.

Front 35

How do H-2 antagonists interact with calcium channel blockers?

Back 35

Cimetidine and ranitidine may increase the plasma concentrations of calcium channel blockers.

Front 36

List risks of chronic treatment.

Back 36

1. Cardiac complications
2. Increased peri-operative bleeding
3. Increased risk of GI hemorrhage
4. Increased risk of developing cancer

Front 37

Verapamil and diltiazem slow heart rate by working on what phase of the SA node action potential?

Back 37

Phase 4

Front 38

Calcium channel blockers such as verapamil ac on what phase of the ventricular action potential?

Back 38

They decrease myocardial contractility by blocking the entry of calcium during phase 2.

Front 39

On what tissue of the heart does verapamil work: atrial muscle, ventricular muscle, nodal tissue, Purkinje network?

Back 39

For therapeutic effect, verapamil works on nodal tissue were it slows phase 4 depolarization.

Front 40

You would use verapamil to treat what dysrhythmias?

Back 40

1.Supraventricular tachycardia
2. A-fib
3. A-flutter

Front 41

What three meds may e used to treat sinus tachycardia?

Back 41

1. Verapamil
2. Beta-blocker
3. Digitalis