L-Type Calcium Channel Blockers (CCBs)

Question 1

three classes

Answer 1

Phenylalkylamines
–Verapamil

Benzothiazepines
–Diltiazem

Dihydropyridines
–“dipine”

Question 2

L-Type Calcium Channels

Answer 2

smooth muscle cells and heart cells

Only Varapamil and Diltiazem affect L-type Ca channels in the heart

Question 3

Verapamil

Answer 3

More selective for heart, less selective for vessels
–not as effective vasodilating

Used as antiarrhythmic and antianginal rather than anti-HTN

***coronary artery dilators!!!! so help w/ angina!

Question 4

Diltiazem

Answer 4

intermediate in selectivity b/w verapamil and dihydropyridines in its selectivity for vascular Ca channels…

antiarrhythmic and anitanginal
(coronary vessel dilations!)

Question 5

Dihydropyridines…effects

Answer 5

Decrease BP and SVR in arterioles AND venules)

Do NOT cause large baroreceptor-mediated sympathetic discharge, so very little change in HR!!!

(EXCEPT short-acting DHP (i.e. nifedipine) do reflexively increase HR by sympathetic activation)

Question 6

nifedipine (regular)

Answer 6

short acting!!
great for relaxing coronaries
not used for HTN b/c reflexively activate SNS, increasing HR

Question 7

DHP clinical uses

Answer 7

–Low renin HTN!!!
(elderly and AA)

–older pts w/ systolic HTN

–Many studies show no survival benefit

Question 8

DHP side effects

Answer 8

Peripheral ankle edema
Hypotension
Constipation
Reflex tachycardia (shorter-acting drugs)