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41 Cards in this Set

  • Front
  • Back
In general, how do calcium channel blockers work?
They interfere with inward calcium ion movement across myocardial and vascular smooth muscle.
What are phenylalkylamines selective for?
AV node
What are dihydropyridines selective for?
Arteriolar beds
What are benzothiazepines selective for?
AV node
In general, what is the mechanism of action of calcium channel blockers?
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
What category of calcium channel blocker does verapamil belong to?
Phenylalkylamines
What are the pharmacologic effects of calcium channel blockers?
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
What are the side effects of Verapamil?
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
What are the clinical uses of verapamil?
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
What is the active metabolite of verapamil?
Norverapamil
How do dihydropyrimidines work?
1. Prevents calcium entry by extracellular allosteric modulation of calcium ion channels.
2. Primary affinity is peripheral arterioles.
3. Reflex tachycardia may be observed.
What calcium channel blocker has the strongest effect on coronary arteries?
Nifedipine
How does nifedipine work?
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.
List clinical uses of nifedipine.
Tx for angina due to coronary artery vasospasm.
List pharmacokinetics of nifedipine.
1. Given orally or sublingually
2. Protein binding of 90%
3. Hepatic metabolism
List side effects of nifedipine.
1. Flushing
2. Vertigo
3. Headache
4. Renal dysfunction may be induced
What is the mechanism of action of benzothiazepines?
It is not well understood.
What category of calcium channel blockers does nifedipine belong to?
Dihydropyrimidines
What category of calcium channel blockers does diltiazepam belong to?
Benzothiazepines
How does diltiazepam work?
1. Blocks calcium channels at the AV node.
2. Minimal cariodpressant effect.
List clinical uses of diltiazepam.
1. Tx for supraventricular tachydysrhythmias.
2. Tx for chronic control of essential HTN
What is the angina dose of diltiazepam?
0.25-0.35 mg/kg IV over 2 minutes then 10 mg/hr infusion for 24 hours.

Decrease dosage in liver disease.
How do digitalis and beta-blockers interact with verapamil and diltiazem?
Pts with preexisiting cardiac conduction abnormalities may experience greater AV block.
How do volatile anesthetics interact with calcium channel blockers?
Exaggerated myocardial depression and peripheral vasodilation.
What might happen to pts with hypovolemic pts who are administered calcium channel blockers?
Exaggerated systemic hypotension.
How can you revers calcium channel blocker toxicity?
1. Calcium chloride
2. Dopamine
What are some pharmacodynamic effects of calcium channel blockers?
1. Vasodilation
2. Myocardial depression
3. Negative inotropic effect
4. Depressant effect on SA node function
5. Peripheral vasodilation
What considerations should you keep in mind on pts undergoing anesthesia who are on calcium channel blockers?
1. Volatile anesthetics have blocking effect on calcium channels.
2. Administer with caution to pts with impaired left ventricular function or hypovolemia.
How do neuromuscular blockers interact with calcium channel blockers?
1. Neuromuscular blockers are potentiated
2. Edrophonium is effective in antagonizing potentiation
How do local anesthetics interact with calcium channel blockers.
May increase local anesthetic toxicity.
How do potassium containing solutions interact with calcium channel blockers?
Hyperkalemia may occur after small endogenous potassium infusion because of blocking of the inward movement of potassium ions.
How does dantrolene interact with calcium channel blockers?
1. Hyperkalemia
2. Cardiovascular collapse
Do calcium channel blockers interfere with calcium medicated platelet functions?
Yes
How does digoxin interact with calcium channel blockers?
Increased plasma concentration of digoxin.
How do H-2 antagonists interact with calcium channel blockers?
Cimetidine and ranitidine may increase the plasma concentrations of calcium channel blockers.
List risks of chronic treatment.
1. Cardiac complications
2. Increased peri-operative bleeding
3. Increased risk of GI hemorrhage
4. Increased risk of developing cancer
Verapamil and diltiazem slow heart rate by working on what phase of the SA node action potential?
Phase 4
Calcium channel blockers such as verapamil ac on what phase of the ventricular action potential?
They decrease myocardial contractility by blocking the entry of calcium during phase 2.
On what tissue of the heart does verapamil work: atrial muscle, ventricular muscle, nodal tissue, Purkinje network?
For therapeutic effect, verapamil works on nodal tissue were it slows phase 4 depolarization.
You would use verapamil to treat what dysrhythmias?
1.Supraventricular tachycardia
2. A-fib
3. A-flutter
What three meds may e used to treat sinus tachycardia?
1. Verapamil
2. Beta-blocker
3. Digitalis