Antihypertensives (Ca Channel Blockers) - Week 2 Flashcards
4 functions of Ca in the body
- signal transduction in CNS and heart
- musc contraction: smooth, cardiac, and vessel walls
- bone health
- clotting cascade
3 primary actions of CCB’s
- negative inotropic effect
- negative dromotropic effect (AV conduction block)
- vasodilation of systemic, splanchnic, coronary, and pulm beds
Dihydropyridines vs non-dihydropyridines
dihydropyridines
- “-ipine”
- strictly arterial vasodilators
- used as anti-HTNs
Non-dihydropyridines
- verapamil and diltiazem
- negative inotropes, neg dromotropes, and vasodilators.
Advantages of Nicardipine
- (dose dependent) Potent arteriole specific vasodilator of systemic, coronary, and cerebral circulations w/o important negative inotropic or dromotropic effects
- no coronary steal syndrome
- offers favorable myocardial O2 supply/demand
- mild natriuretic effect
Why is Nicardipine good for emergent HTN?
onset <1 min, duration 15-20 min
Why is Nicardipine useful for IV control of HTN in PACU and ICU?
- slower onset and offset than SNP
- easier to use
- fewer BP swings
- no rebound HTN w w/d (don’t have to taper it)
- Reflex tachycardia <10 bpm
- prolonged duration of action by a be beneficial post-op
Disadvantages of Nicardipine
- may accumulate
- variable duration of action
- HoTN
- venous irritation
- may cause tachycardia
Advantages of Clevidipine
- reduced need for other anti-HTNs
- reliable control
- no dose adjustments for renal/hepatic disease
- ready to use vial
- no sig myocardial depress
- no effect on preload
- low potential for drug interactions
Clevidipine disadvantages
- lipid emulsion
- continuous monitoring required
- contraindicated w egg and soy bean allergy, pancreatitis, and HLD
- slower onset than nicardipine
3 functions of verapamil (phenylalkylamine class)
- potent negative inotrope
- dromotrope
vasodilator
3 good uses for verapamil
- AS and IHSS
- Conversion of atrial re-entry tachyarrhythmias
- coronary artery vasospasm (Prinzmetal angina)
_______, of the benzothiazine class, fits b/t verapamil (phenylakylamine) and dihydropyridines in action
Cardizem
Uses for Cardizem
- rate control in a.fib and atrial tachicardia vs a conversion agent like verapamil
Things to remember about verapamil
- potent neg inotrope and dromotrope
- mild vasodilator
- good for tx of vasospastic angina and essential HTN
Things to remember about cardizem
- fits b/t verapamil and dihydropyridines in action
- less neg inotropic and dromotropic effects than verapamil but more than dihydropyridines
- mild vasodilator like verapamil
Things to remember about dihydropyridines
- virtually pure arterial vasodilator
- lack clinically sig neg inotropic and dromotropic effects
CNS s/e of CCBs
- dizziness, HA, Fatigue, insomnia, nervousness
from fluctuations in BP
CV s/e of CCB’s
DHP: flushing, edema, palpitations
NDHP: bradycardia from blocking the AV node
Resp s/e of CCB’s
Nasal congestion, dyspnea, cough (nifedipine mostly)
GI and other s/e of CCB”s
N/V/D
arthralgias/joint stiffness, itching
How do verapamil and diltiazem enhance myocardial O2 balance?
- decrease myocardial O2 consumption by after load reduction and/or neg inotropic effect
- increase O2 delivery through coronary vasodilation
How do dihydropyridine vasodilators worsen MvO2?
they cause diastolic HoTN and reflex tachycardia (except nicardipine)
T/F CCB’s decrease repercussion injury after ischemia.
True. b/c they decrease O2 demand.
How do CCB’s affect renal fx?
increase RBF and GFR and induce natures
*Benefits can be reversed if they cause HoTN, reflex catecholamine release, and angiotensin activation leading to decreases in RBF and GFR
