Nordgren: Anti-anginal drugs Flashcards
What drugs are traditionally used as anti-anginals?
- Organic nitrates
- Ca channel blockers
- β-Adrenoceptor Antagonists (Blockers)
Why do we use anti-anginal drugs?
- They all decrease myocardial 02 demand!
2. They can increase 02 supply to ischemic tissues
What happens when you decrease myocardial 02 demand?
It leads to a decrease in: HR ventricular volume bp contractility
What may someone who’s been on a nitrate for a long time encounter?
They may develop a tolerance to the drug.
What drugs cause venodilation more than arterial dilation?
Nitrates
What does venodilation do?
Decreases:
- preload (VFP)
- pulmonary vascular resistance
- decreased pulmonary left ventricular end-diastolic pressure
Why might you see a slight decrease in TPVR and slight increase in HR at higher doses of nitrates?
A decrease in left ventricular end diastolic pressure (decreased SV) triggers baroreceptors and results in an increase in HR and an increase in contractility.
If you give someone a nitrate, how does this affect the distribution of blood flow?
A nitrate doesn’t change the total coronary blood flow but it does decrease left ventricular end-diastolic volume and pressure, leading to REDISTRIBUTION of blood to the ENDOCARDIUM.
What will giving someone a nitrate do overall in terms of supply and demand?
- It will decrease left ventricular end diastolic pressure (supply) which will in turn decrease the preload (demand).
- A decrease in pressure triggers baroreceptors to increase HR and contractility at high doses.
What is the MOA of nitroglycerine?
Releases NO in smooth muscle>
activates guanyl cylase>
increase cGMP
What are the pathophysiological reasons for giving a patient nitro?
NO> smooth muscle relaxation> decreases venous return> decrease in heart size> increase coronary flow in some areas
What do you use nitroglycerine for and what are the different ways to give it?
Angina
- Acute episodes- sublingual
- prophylaxis- oral and transdermal
- ACS- IV
What is the negative of giving someone an oral dose of nitro?
Nitroglycerine has a HIGH FIRST PASS METABOLISM so an oral dose of nitro must be much bigger than a sublingual one.
Why might reflex tachycardia, and headache be observed when you’ve given a pt nitro?
Nitro can lead to a decrease in pressure which triggers baroreceptors and can increase HR leading to reflex tachycardia.
What drugs do you want to avoid if you’re taking nitroglycerine?
Phosphodiesterase type 5 inhibitors (viagra, cialis, levitra)
They can cause synergistic HYPOTENSION.
Why would you give someone isosorbide dinitrate over nitroglyercine?
slightly LONGER duration of action
What is isosorbide mononitrate used for?
It’s an active metabolite of dinitrate that’s used for prophylaxis.
How would you give a pt a Ca channel blocker?
Orally
How does a Ca channel blocker increase the supply of oxygenated blood to the heart?
- Smth muscle relaxation> Increase total coronary blood flow> decreases aortic diastolic P
How does a Ca channel blocker decrease the demand for O2 of the heart?
- Decreases heart rate
2. decreases contractility
What is the MOA of verapamil and diltiazem?
NONSELECTIVE block of L type Ca channels in VESSELS and HEART
What are the pathophysiologic effects of Ca blockers?
Reduce:
vascular resistance
Decreased contractility and conductivity of the heart–>
DECREASED 02 demand
What do you use Ca channel blockers for?
Prophylaxis of angina
Hypertension
What must you be careful of when you’re giving a pt verapamil or diltiazem?
AV block, or acute heart failure
They are also additive with other cardiac depressants and hypotensive drugs
