Calcium Channel Blockers

Question 1

How do calcium channel blockers affect vascular
smooth muscle? How does this affect a person’s
blood pressure?

Answer 1

Calcium channel blockers relax vascular smooth muscle,
causing a reduction in blood pressure.
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 203.

Question 2

Is orthostatic hypotension a common adverse side
effect seen in patients who take calcium channel
blockers?

Answer 2

No.
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 203.

Question 3

In addition to vascular smooth muscle, what other
smooth muscle is affected by the actions of calcium
channel blockers?

Answer 3

Uterine, bronchiolar, and GI smooth muscle
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 203.

Question 4

List the calcium channel blockers that fall under the

category of dihydropyridines.

Answer 4

Nifedipine, Nisoldipine, Nicardipine, Felodipine, Amlodipine,
Isradipine
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 202.

Question 5

Once a calcium channel blocker binds to its receptor,
how does the channel respond to depolarization in
cardiac muscle? In smooth muscle?

Answer 5

The channel does not open as frequently, causing a drastic
reduction in the transmembrane calcium current. This results in
a reduction in the SA pacemaker rate, a reduction in the AV
node conduction velocity, a decrease in contractility of cardiac
muscle, and relaxation of smooth muscle.
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 203.

Question 6

What are the 3 classifications of calcium channel

blockers?

Answer 6

1. Dihydropyridines 2. Phenylalkylamines 2. Benzothiazepines
   Stoelting RK, Hillier SC. Pharmacology and Physiology in
   Anesthetic Practice. Philadelphia, PA: Lippincott Williams and
   Wilkins; 2006: 387.

Question 7

What specific calcium channel is predominant in

smooth and cardiac muscle?

Answer 7

The L-type calcium channel
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 202.

Question 8

List the desirable effects of calcium channel blockers.

Answer 8

Decreased heart rate, a reduction in myocardial contractility,
decreased activity of the SA node, reduced rate of cardiac
impulse conduction through the AV node, relaxation of vascular
smooth muscle resulting in vasodilation and a reduction in
systemic blood pressure.
Stoelting RK, Hillier SC. Pharmacology and Physiology in
Anesthetic Practice. Philadelphia, PA: Lippincott Williams and
Wilkins; 2006: 388.

Question 9

List common side effects of calcium-channel

blockers.

Answer 9

Peripheral edema, headache, flushing, and systemic
hypotension.
Stoelting RK, Hillier SC. Pharmacology and Physiology in
Anesthetic Practice. Philadelphia, PA: Lippincott Williams and
Wilkins; 2006: 387.

Question 10

What calcium channel blocker falls into the category

of a benzothiazepine?

Answer 10

Diltiazem
Stoelting RK, Hillier SC. Pharmacology and Physiology in
Anesthetic Practice. Philadelphia, PA: Lippincott Williams and
Wilkins; 2006: 388.

Question 11

What two calcium channel blockers possess local

anesthetic activity?

Answer 11

Diltiazem and verapamil
Stoelting RK, Hillier SC. Pharmacology and Physiology in
Anesthetic Practice. Philadelphia, PA: Lippincott Williams and
Wilkins; 2006: 395.

Question 12

What calcium-channel blockers are effective in the

treatment of coronary artery spasm?

Answer 12

All calcium-channel blockers effectively treat coronary artery
spasm.
Stoelting RK, Hillier SC. Pharmacology and Physiology in
Anesthetic Practice. Philadelphia, PA: Lippincott Williams and
Wilkins; 2006: 388.

Question 13

What two calcium-channel blockers exert the most

negative inotropic effects?

Answer 13

Diltiazem and verapamil
Stoelting RK, Hillier SC. Pharmacology and Physiology in
Anesthetic Practice. Philadelphia, PA: Lippincott Williams and
Wilkins; 2006: 388.

Question 14

What calcium channel blocker exerts the greatest

degree of vasodilation?

Answer 14

Nicardipine
Stoelting RK, Hillier SC. Pharmacology and Physiology in
Anesthetic Practice. Philadelphia, PA: Lippincott Williams and
Wilkins; 2006: 393.

Question 15

Verapamil should not be administered to patients

with what conditions? Why?

Answer 15

Severe bradycardia, heart failure, dysfunction of the sinus node,
or AV nodal block. Verapamil has a negative chronotropic
effect on the SA node, a negative inotropic effect on cardiac
muscle, and severely depresses the AV node.
Stoelting RK, Hillier SC. Pharmacology and Physiology in
Anesthetic Practice. Philadelphia, PA: Lippincott Williams and
Wilkins; 2006: 389.

Question 16

Why should verapamil be used cautiously in patients

with Wolff-Parkinson-White syndrome?

Answer 16

patients
with Wolff-Parkinson-White syndrome?
Verapamil can augment conduction of cardiac impulses over
accessory tracts through reflex sympathetic nervous system
activity. This creates an increase in the rate of the ventricular
response, which may lead to ventricular dysrhythmias.
Stoelting RK, Hillier SC. Pharmacology and Physiology in
Anesthetic Practice. Philadelphia, PA: Lippincott Williams and
Wilkins; 2006: 384, 389

Question 17

What two drugs can be used to partially reverse
toxicity caused by an overdose with a calcium
channel blocker?

Answer 17

IV dopamine or calcium
Stoelting RK, Hillier SC. Pharmacology and Physiology in
Anesthetic Practice. Philadelphia, PA: Lippincott Williams and
Wilkins; 2006: 394.

Question 18

What calcium channel blocker is useful in the
prevention and treatment of cerebral vasospasm that
often occurs with a subarachnoid hemorrhage?

Answer 18

Nimodipine
Stoelting RK, Hillier SC. Pharmacology and Physiology in
Anesthetic Practice. Philadelphia, PA: Lippincott Williams and
Wilkins; 2006: 393.

Question 19

Do calcium channel blockers potentiate the effects of
nondepolarizing and depolarizing neuromuscularblocking
drugs?

Answer 19

Yes. Calcium channel blockers do not have skeletal muscle
relaxant properties on their own, but they can potentiate the
effects of nondepolarizing and depolarizing neuromuscularblocking
drugs.
Stoelting RK, Hillier SC. Pharmacology and Physiology in
Anesthetic Practice. Philadelphia, PA: Lippincott Williams and
Wilkins; 2006: 395.

Question 20

What calcium channel blocker falls under the

classification of a phenylalkylamine?

Answer 20

Verapamil
Stoelting RK, Hillier SC. Pharmacology and Physiology in
Anesthetic Practice. Philadelphia, PA: Lippincott Williams and
Wilkins; 2006: 388.