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