Pharmacology: Cardiovascular Drugs Flashcards
First line treatment for high blood pressure, when do you give ACEi/ARBs and when do you give CCBs?
ACEi/ARB:
- Hypertension with diabetes
- Hypertension without diabetes, < 55 and not of african decent
CCBs:
- Hypertension without diabetes, >55 or of african decent
So you’ve tried someone on ACEi/ARBs and CCBs for hypertension and it’s still not working. What is the next step?
Thiazide-like diuretic
How do ACEi work?
They block the conversion of angiotensin 1 into angiotensin 2
How does angiotensin II contribute to high blood pressure?
It cause vasoconstriction.
It causes an increase in blood volume by more H2O from vassopressin release and more Na+ from aldosterone release.
What is a side effect of blocking angiotensin converting enzyme using ACEi?
The enzyme also breaks down bradykinin so blocking it leads to a build up.
Bradykinin not only contributes to vasodialation but also makes vessels leaky leading to odema
Examples of ACEis
Ramipril
Lisinopril
Perindopril
Enalapril
Pril - April - Albie - ACE
How to ARBs work?
Angiotensin II receptor blockers
They block angiotensin II from acting therfore having the same effect as ACEi but without the bradykinin buildup
Examples of ARBs
Losartan
Candesartan
Valsartan
Irbesartan
‘Artan - Tartan
ARB - arbeleser - french
Ald alliance
How do calcium channel blockers work?
Smooth muscle needs external calcium to contract
By blocking these channels it decreases contractability of the smooth muscles therefore cause vasodilation and decreases stroke volume of the heart.
It also slows conduction of the heart therefore decreasing heart rate
All of these lead to lower BP
Three ways CCBs contribute to a lower BP?
- Vasodilation
- Cardiac muscle contractibility
- Lowers heart rate
Example of a CCB
Amlodapine
Pine - no pines on The Downs - with pines there no calium (chalk)
How do thiazide and thiazide like diuretics work?
They act to inhibit the co transport of Na+ and Cl- in the distal convoluted tubule of the kidney
This causes there to be more Na+ in the urine therefor the urine will absorb more water. More Na+ and H2O are excreted resulting in lower blood pressure
Why are thiazide diuretics capped at retaining 5-10% of filtered Na+?
Because they only act on the distal convoluted tube where active transport occurs
Majority of Na+ transport accurs passively in the promimal convoluted tubule
How do potassium sparing diuretic work?
They block aldosterone receptors which exchange Na+ for K+ thus increasing Na+ and H2O secretion
Main difference of thiazide diuretic and potassium sparing diuretics?
Thiazide diuretics cause a decrease in potassium also because there is more Na+ to exchange with
Potassium sparing increase potassium
How to remember if a drug is a thiazide diuretic?
Its name will end in thiazide e.g. bendroflumethiazide
Thiazide-like one don’t end in thiazide - these are all different so bun remembering
How to remember if a drug is a potassium sparing diuretic?
The end in ‘one and they block aldosterone e.g. spironolactone
Last drug family that can also be used for hypertension?
Beta blockers
How to remember if a drug is a beta blocker?
They all end in ‘olol e.g. atenolol
Beta - lol - olol
Decribe broadly the treatment for each of these stages of cardiac ischemia
What are nitrates?
The are precursors for nitric oxide which is a vasodialator
When are nitrates used?
Heart failure
An example of a nitrate?
Glycerol Trinitrate (GTN) “nitroglycerin”
With regard to cardiovascular when might you use a beta blocker?
With angina - reduces work heart has to do
What is the purpose of using raas drugs when treating heart ischemia?
Mostly to decrease afterload (blood pressure) and venous return
In what way does vasodilation from nitrates help with cardiac failure?
It most act ont he venous side not arterial. By dilateing the viens it decreases venous return and thus how much the heart has to work though prevent pooling and odema
How to statins work?
They inhibit the production of cholesterol
How does aspirin have anti-thrombitic effects?
It inhibits cox1 which in turn inhibits the production of thromboxane A2 which is a platelet activator
Aspirin is a anti-platelet not an anticoagulant, it prevents clotting not coagulation
What is dalteparin
A low molecular weight heparin
It is a standard prophylactic against DVT or other thrombitic diseases
Where does heparin act?
It directly blocks factor Xa which is central for the coagulation cascade
It also inhibits thrombin or factor IIa which converts fibrinogen into fibrin
Naming of DOACs
dabigatran, apixaban and rivaroxaban
aban or atran
a ban on a tran (train)
What is DOACs mechanism of action?
The bans directly block factor 10a
The trans block thrombin
Warfarin mechanism of action
describe the extrinsic pathway of the coagulation cascade up to Xa
It goes XII->XIIa
XI->XIa
IX->IXa
Both IXa and VIII are required for X->Xa
X -> Xa
describe the intrinsic pathway of the coagulation cascade up to Xa
VII->VIIa
VIIa plus tissue factor convert X->Xa
Decribe the coagulation cascade from Xa onwards (common pathway)
Xa converts
Prothrombrin->Thrombrin (factor IIa)
Thrombrin converts
Fibrinogen->Fibrin(factor Ia)
At the end factor XIII is also thrown in for good measure
What is a common side effect of an ACEi?
Cough
It also blocks the breaks down of bradykinin causing build up in the blood
Bradykinin induces sensitization of airway sensory nerves via rapidly adapting stretch receptors and C-fiber receptors that releases neurokinin A and substance P. This causes airway smooth muscle to constrict leading to bronchoconstriction and cough.
A 65yo man of african-caribbean heritage has hypertension. No pmh and is a non-smoker
What would be the first line drug of choice?
ACEi
Thiazide diuretic
Potassium sparing diuretic
CCB
CCB
e.g. amlodipine
What effect would a beta2 agonist have on serum potassium level?
Decrease serum potassium
Increase intracellular potassium
What effect would a beta2 agonist have on serum calcium level?
Increase serum calcium
Decrease intracellular calcium (needed for contraction) by pumping it out and by pumping it into the SR
