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)
ACE Inhibitors
Prevent the conversion of angiotensin I to angiotensin II
Inhibits the ACE enzyme, not the angiotensin 2 directly
All ACE Inhibitors end in ____
-pril
ARBs
Angiotensin Receptor Blockers
Block binding of angiotensin II to receptors
All ARBs end in ____
-sartan
Angiotensin II (ACE) Inhibitor Prototype Drug
lisinopril (Prinivil, Zestril)
Action of lisinopril
Inhibits ACE to prevent angiotensin I –> Angiotensin II conversion
What is the result of lisinopril inhibiting ACE
- reduced vascular tone and a direct lowering of BP
- Decreased aldosterone release and less Na Retention –> Less Na retention means less water retention meaning a DIURETIC EFFECT and decreases BP
Route of lisinopril
mostly Oral
ADRs of lisinopril
- ACE INHIBITOR COUGH - Dry nonproductive cough, chronic - 5-30% get this
- HYPOTENSION
- POSSIBLE HYPERKALEMIA
Other: Pruritis, Rashes, Dizziness, HA
Rare: Neutropenia, agranulocytosis, hepatotoxicity
Why is there a risk for hyperkalemia with lisinopril
because there is less Na retention leading to increased K retention
What could be concerning for a renal impaired patient taking lisinopril
the retention of K they cannot rid of
We would never give anyone on an ACE inhibitor what kind of drug alongside it
any drug that increases Potassium
What is the Black Box Warning for All Ace Inhibitors like Lisinopril
Fatal Injury and death when taking during pregnancy - mainstay of therapy for heart failure
What are the 2 effects ACE Inhibitors can do that is helpful
- Anti-hypertensive
2. Treatment of heart failure
Why can ACE inhibitors be used for heart failure treatment
because it blocks aldosterone and also low sodium retention decreases fluids thus decreasing strain
Angiotensin II Receptor Antagonist (ARB), Antihypertensive Prototype Drug
losartan (Cozaar)
What ADR seen in ACE inhibitors is not seen with ARBs
the cough
Action of losartan
Blocks binding of Angiotensin II to type I receptors in blood vessels and other tissues
Inhibits RAA system better and more selectively than ACE inhibitors
Route of losartan
oral
ADRs of losartan
HYPOTENSION
DIZZINESS
Other: Insomnia, GI, Muscle Pain and Cramps, Occasionally increased liver enzymes
NOT AND ADR = COUGH
Black Box Warning for ARBs like losartan
Do not use in pregnancy because of effects in the RAA system
Same as ACE inhibitor’s black box warning
Maximum effect for losartan is seen when?
within 3-6 weeks
Why is losartan sometimes given with a diuretic like HCTZ in the form of the combo drug Hyzaar
for a boosted anti hypertensive effects
Things that ACE Inhibitors Do
Vasodilation
Decreased blood volume (less sodium retention)
Decreased cardiac and vascular remodeling
Potassium retention
Fetal injury
What is it about ACE Inhibitors that leads to the unique cough
ACE inhibitors also prevent the breakdown of BRADYKININ (which is a vasodilator and inflammatory mediator) –> This leads to Vasodilation, Rare Angioedema, and the COUGH
Angina Pectoris
a symptom of transient myocardial ischemia perceived as chest pain or discomfort.
Generally precipitated by a condition that increases myocardial oxygen demand or decreases oxygen supply (primarily in diseased vessels – but can be in normal ones if constricted).
3 Classes of Drugs for Angina Pectoris Treatment
Nitrates
Beta Blockers
Calcium Channel Blockers
How do nitrates help treat angina
reduce O2 demand by reducing preload and afterload
How do beta blockers help treat angina
decrease O2 consumption by decreasing heart rate, BP, and myocardial contractility
Blocking Beta 1 causes decreased HR and contractility, also decrease reflex tachycardia caused by other drugs
How do calcium channel blockers help treat angina
produce coronary and systemic arterial vasodilation, reduce afterload, HR, and contractility
Have many actions beside anti anginal effects but reduces myocardial O2 consumption
Anti Anginal Prototype Drug
Nitroglycerin
Action of Nitroglycerin
Relaxes vascular smooth muscle and both arterial and venous vessels BUT works mainly on the venous system in those with CAD - exact mechanism is unknown but peripheral resistance decreases and venous return to the heart is decreases!
Dilating veins decreases preload and BP
Net result: decreased myocardial O2 consumption and angina relief
What is the issue with Nitroglycerin and CAD
those with CAD are physically unable to have their vessels dilate with nitroglycerin since they are hardened
Why can nitroglycerin still be helpful despite someone having CAD
It cannot dilate the coronary arteries, but it will dilate everything else - like the venous system - so blood can stay in extremities instead of going back into the heart which will decrease preload and work load overall since there is less circulation going to the heart –> results in cardiac demand decreasing
So basically, it opens everything else up beside the coronary vessels
What is the preferred route of absorption for nitroglycerin?
Sub-lingual (under tongue and absorbed quickly) very well
Can also be given IV oral and skin
ADRs of Nitroglycerin
HA (Dilated vessels in the head causing a pounding HA)
!!REFLEX TACHYCARDIA
!!HYPOTENSION (all the smooth muscles are relaxing)
Other: Dizziness, Syncope, Flushing of skin
Why does BP need to be checked 5 minutes after giving Nitroglycerin
drops BP and this can happen fast
What needs to be done when giving nitroglycerin
you have to wear gloves because it can absorb through the palms and give a pounding headache for the nurse as well
What is unique about nitroglycerin dosage
it is INDIVIDUALIZED
Used to be take 3 tablets then call 911 - but now you take one tablet and if it doesnt help call 911 (dont drive and dont have someone else drive you)
When is nitroglycerin use contraindicated
When another drug that causes blood vessel dilation - such as sildenafil (Viagra) - is taken because it can cause life threatening hypotension and cardiac collapse
Nitrate Tolerance
Tolerance occurring for nitroglycerin in its topical patch and ointment form
Creating a nitrate free period of 10-12 hours without the patch while they sleep can prevent this