CCBs Flashcards
Use-dependent binding to L-type calcium channels
Non-dihydropyridines
targets cardiac cells
can only attach to inside calcium channel when it’s in its open conformation
- -very rapid depolarization and repolarization in heart, so channel opens more frequently
- -more opportunity for binding!
Voltage-dependent binding to L-type calcium channels
dihydropyridines
targets smooth muscle
Much slower depolarizations and repolarizations
- -DHP don’t require open channel, but they do require certain voltage
- -b/c smooth muscle spending a lot more time at certain voltage (it’s slow), more opportunity for DHP to bind
Non-Dihydropyridines
direct effects predominate
decrease:
- -HR
- -contractility
- -AV conduction rate
–> reduces demand and prevents/ reverses vasospasm
Don’t combine with Beta Blockers!!
Dihydropyridines
more potent vasodilators–>reflex cardiac stimulation
direct and indirect effects balanced
Reduces demand by reducing afterload
increases supply by coronary vasodilation
Combine w/ Beta Blockers!!!
Nifedipine
Felodipine
Amlodipine
arterial vasodilation!
Verapamil
Diltiazem
minimal arterial vasodilation
Negative chronotropic and inotropic effects
especialy verapamil!
DHP adverse effects
excessive vasodilation…
peripheral edema (b/c increased precapillary dilation)
paradoxical exacerbation of angina
(dilated skeletal muscle vessels stealing all supply from coronary vessels…decreased supply)
Non-DHP adverse effects
bradycardia
asystole
AV block
**contraindicated in HF!
pregnancy category C
Highly effective agents for relief in…
exertional and vasospastic angina
In pts w/ CAD, CCBs…
fail to prevent reinfarctions or CHD death
Impaired LV function…increases mortality
BBs are better
CCBs in HTN
higher rates of MI, HF (immediate release)
less CV events (slow-release)
CCBs in cancer
may inhibit apoptosis
Best class for treatment of angina
BBs
(unless they aren’t tolerated)
or possibly added on to BB + nitrate if angina still not controlled
