Week 11: Cardiovascular Part 2 Flashcards
Vasodilators
drugs that reduce BP by acting directly on vascular smooth muscle and thereby decrease peripheral resistance
can act as anti-hypertensives
2 Kinds of Vasodilators
- Selective to arterioles (only dilate arterioles - ex: Hydralazine) - Direct Vasodilator
- Affect both arterioles and veins (Huge effect on the body - ex Nitroprusside - will oftne need to be titrated)
Selective to arteriole vasodilators will decrease ____
afterload
Vasodilators affecting arterioles and veins decrease ___ and ___
afterload and preload
The fastest acting antihypertensive type is…
vasodilators that affect the arterioles and the veins
How can vasodilators precipitate angina, MI, or CHF?
SNS will activate by reflex action which can lead to increased HR, CO, and force of contraction
This means generally there needs to be a combined therapy with something like a beta blocker
What is the prototype direct vasodilator, antihypertensive drug
hydralazine (Apresoline)
Action of hydralazine
thought to have direct action on blood vessels, to cause arteriolar vasodilation and increase renal blood flow (helps the kidneys)
What is the bonus effect of a vasodilator like hydralazine
it also increases renal blood flow which is beneficial for the kidneys
What is the most common route for hydralazine and why is it this important to know?
Oral - because it has an extensive first pass
ADRs of hydralazine
HYPOTENSION
(Reflex) PALPITATIONS/TACHYCARDIA
Other: HA, Anxiety, Mild Depression, Dry mouth, Unpleasant taste in mouth, NV
What kind of vasodilator is hydralazine
direct acting vasodilator
so it is selective to arterioles
Why is there frequent monitoring in the early stages of hydralazine therapy?
Because of differences in metabolism, some people metabolize this quicker while others do not so we need to be monitoring the BP response to watch for the effect
Calcium Channel Blockers
Type of drug that causes arteriolar dilation, blocks the renin system, AND DECREASES MYOCONTRACTILITY
It inhibits the movement of Ca ions across cell membranes to decrease mechanical contraction of the heart
“Calcium Antagonists”
Does perform some coronary vessel and peripheral artery dilation but focuses on cardiac muscle membranes
Calcium Channel Blocker results and treatment is similar to what other type of drug for antihypertension
Beta Blockers (but this works on calcium instead)
Calcium antagonist (Ca Channel Blocker), Antianginal, and Antiarrhythmic (and by result Antihypertensive) Prototype Drug
verapamil (Calan, Isoptin)
Action of verapamil
produces blockage of calcium channels in blood vessels and in the heart (Dual Effect)
This leads to a multitude of effects where the HR slows and does not beat as strong - similar in some ways to beta blockers
What are the 6 important effects of verapamil’s action
- Arteriolar Dilation and resultant lowering of BP
- Increase in coronary perfusion
- Slows SA node causing reduction in heart rate
- Decrease in nodal; conduction in AV node
- Decrease in force of myocardial contraction
- inhibition of renin release
Route of verapamil
oral - but there is an extensive 80-90% first pass so there is an IV form for emergencies
ADRs of verapamil
BRADYCARDIA
HYPOTENSION
SEVERE TACHYCARDIA (Some Reflex)
CONSTIPATION (HIGHER THAN IN OTHER DRUGS)
Other: Nausea, Discomfort, Dizziness, HA, Flushing, Pruritis
When is verapamil contraindicated
In an AV block and conditions of reduced myocardial contractility, severe hypotension, and severe CHF
- avoid conduction problems, reduced contractility, further drops in BP and worsens heart failure
What could increase calcium channel blocker levels (like verapamil) if taken with the drug
Grapefruit Juice (So dont drink it)
Renin-Angiotensin System Antagonists
Newer class of drugs - 1980s
Inhibits the action of renin-angiotensin-aldosterone system
Includes ACE Inhibitors and ARBs
can act as antihypertensives
Angiotensin II is a potent ____
vasoconstrictor (so if we block it we can open vessels and decrease BP)